research article influence of tensile speeds on the...
TRANSCRIPT
Research ArticleInfluence of Tensile Speeds on the Failure Loads of the DP590Spot Weld under Various Combined Loading Conditions
Jung Han Song1 and Hoon Huh2
1Metal Forming RampBD Group Korea Institute of Industrial Technology 156 Gaetbeol-ro Yeonsu-guIncheon 406-840 Republic of Korea2School of Mechanical Aerospace and Systems Engineering Korea Advanced Institute of Science and TechnologyDaeduk Science Town Daejeon 305-701 Republic of Korea
Correspondence should be addressed to Jung Han Song jhsongkitechrekr
Received 13 November 2014 Accepted 10 December 2014
Academic Editor Doo-In Kim
Copyright copy 2015 J H Song and H Huh This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited
This paper is concerned with the evaluation of the dynamic failure load of the spot weld under combined axial and shear loadingconditions The testing fixture is designed to impose the combined axial and shear load on the spot weld Using the proposedtesting fixtures and specimens quasi-static and dynamic failure tests of the spot weld are conducted with seven different combinedloading conditions The failure load and failure behavior of the spot weld are investigated with different loading conditions Effectof tensile speeds on the failure load of the spot weld which is critical for structural crashworthiness is also examined based on theexperimental data The failure loads measured from the experiment are decomposed into the two components along the axial andshear directions and failure contours are plotted with different loading speeds Dynamic sensitivities of failure loads with variouscombined loading conditions were also analyzed Experimental results indicate that the failure contour is expanded with increasingloading speeds and failure loads show similar dynamic sensitivity with respect to the loading angles
1 Introduction
Increasing concern of environmental safety and reductionof fuel consumption motivates car manufacturers to uselightweightmaterials having a higher tensile strength coupledwith better ductility By reducing the weight of a car less fuelconsumption along with less CO
2emission can be achieved
Considering the safety standards required in the automobileindustry dual phase (DP) steel has gained its popularity asthis steel has a higher tensile strength in conjunction withhigher elongation compared to the steel grades of similaryield strength [1] The resistance spot welding process hasbecome indispensable in the joining of sheet metals in theautomobile industry since the 1950s Because a modernvehicle typically contains several thousand spot welds it isextremely important to understand the strength of the spotweld under quasi-static fatigue and impact loading condi-tions in order to evaluate durability and crashworthiness ofan auto-body [2] Failure of a spot weld is likely to occur
prior to failure of the base metal when a large load is appliedto the structure since extremely high stress is concentratedat the interface between the nugget and the base metal [3]It is necessary to estimate the strength of spot welds of DPsteel sheets in order to provide a failure criterion of a spotweld in the structural analysis or crashworthiness assessmentof auto-body members For that purpose lab-shear testscoach-peel tests and cross-tension tests have been elaboratelyperformed to estimate the failure loads of the spot weld [4ndash6]It is however insufficient to perform simple lap-shear testsand cross-tension tests to construct the failure criteria thatdescribe the behavior of spot welds under combined loadingconditions because spot welds in automotive componentsare subjected to complicated loading conditions when theyundergo deformation
With advances in computer simulation technology auto-motive companies attempt to implement accurate spot weldmodels into finite element analysis so as to predict thefailure of spot-welded components in the crash analysis of
Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2015 Article ID 297915 9 pageshttpdxdoiorg1011552015297915
2 Advances in Materials Science and Engineering
Pull bar(lower)
Fixing block
Specimen
Pin-joint
Fixture
Pull bar(upper)
(a)
0∘ 15∘ 30∘
45∘ 60∘ 75∘
(b)
Figure 1 Fixture set with pin-joints for failure tests of a spot weld under combined loading conditions (a) schematic diagram of a fixture(b) fabricated testing fixtures at various loading angles
NuggetHAZ
Base metal
Thick platewith a hole
Thick platewith a hole
Nugget
Specimen
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
Shea
r loa
d (k
N)
Axial load (kN)
0∘
15∘
15∘
30∘
30∘
35∘
25∘
40∘
45∘
45∘50∘
55∘
60∘
60∘65∘
70∘
75∘
75∘80∘
85∘90∘
10∘
20∘
5∘
(b)
Figure 2 Design of specimen to impose the constant ratio of axial and shear loads on the spot weld during tests schematic description of aspecimen with a guide plate (b) loading path acting on the spot weld at various loading angles (FEM results)
an auto-body In order to describe the failure of a spotweld in the crash analysis it is necessary to evaluate thefailure characteristics of a spot weld under impact loadingcondition Birch and Alves [7] conducted dynamic lap-sheartests of spot-weldedmild steels using a servohydraulic testingmachine Schneider and Jones [8] performed dynamic coach-peel tests at a crosshead speed of 08ms Bayraktar et al [9]
investigated dynamic failure loads of spot-welded lap-shearspecimens using a Charpy impact test Their experimentalresults revealed that the dynamic failure load of spot weldsincreases relative to the quasi-static failure load Sun andKhaleel [10] also observed the strain-rate dependent failureload of spot welds in dynamic cross-tension tests Khan etal conducted drop weight test using lab-shear specimen to
Advances in Materials Science and Engineering 3
FS
FN
120601
x998400
z998400
x
z
Fz
120601
Figure 3 Decomposition of the applied load on a spot weld into theaxial and the shear component at the loading angle of 120601
investigate the impact performance of spot welds in advancedhigh strength steels [11] It is however not feasible to performdynamic lap-shear cross-tension and coach-peel tests forconstructing a strain-rate dependent failure criterion thatdescribes the behavior of spot welds under impact loadingconditions because spot welds in automotive components aresubjected to complicated dynamic loading conditions whenthey undergo crashed deformation [12]
In this paper the failure behavior of the DP590 spot weldunder combined loading conditions is investigated underquasi-static and impact loading condition Dynamic failuretests of the spot weld are conducted with seven differentcombined loading conditions at various tensile speeds fromquasi-static to 12ms Dynamic effects on the failure load ofthe spot weld which is critical for structural crashworthinessare examined based on the experimental data
2 Dynamic Failure Tests of a Spot Weld underCombined Loading Conditions
21 Testing Fixtures to Impose Combined Loading Conditionson the Spot Weld In order to impose the combined axialand shear loads on a spot weld specially designed testingfixtures and specimens were adopted in this paper [13] Thetesting fixture shown in Figure 1 contains the pin-joints thateliminate the horizontal force and bending moment Thespecimen shown in Figure 2(a) involves guide plates thatprevent unfavorable rotation of the nugget due to bendingdeformation The testing fixture and specimen ensure acombined loading conditionwith a constant ratio of the shearload to the axial load during the test as shown in Figure 2(b)[13] Therefore as explained in Figure 3 the applied load 119865
119911
can be decomposed into the axial load 119865119873
and the shear
load 119865119878at the nugget region using the simple trigonometric
functions
119865119873= 119865119911cos120601
119865119878= 119865119911sin120601
(1)
Here 119865119873 119865119878 and 120601 denote the axial load the shear load and
the initial inclined angle with respect to the pulling directionrespectivelyThe inclined angle120601 is equal to the loading anglewhich represents the angle between the load application lineand the centerline of the specimen
22 Testing Material and Preparation of Specimen The spotweld of DP590 with the thickness of 10mm is considered inthis paper The chemical compositions are listed in Table 1Prior to spot welding of a specimen the specimen surfacewas wiped with a weak acetone solution using a cloth inorder to remove grease and dirt from its surface Spotwelding was then performed using a static spotprojectionwelding machine The welding schedules shown in Table 2were determined after several trials with the aid of industrystandards to guarantee a button-type failure
The specimen used in the tests is shown in Figure 4(a)To restrict the bending of the region outside the spot weldtwo guide plates made of SPFC590 steel with the thickness of32mm were attached onto the outsides of the specimen inthe following procedure
(1) Two guide plates with a hole at the center are pre-paredThickness and hole diameter of the guide plateare 32mm and 10mm respectively
(2) A guide plate was joined with a steel sheet on one sideusing six points of spot welding around the hole at thecenter of the guide plate
(3) Two pairs of the joined guide plate and the steel sheetwere spot welded to each other through the holes atthe center of guide plates
As the diameter of the hole in the guide plate was 10mmthe six spot weld points that joined the guide plate and thesteel sheet only serve to prevent excessive bending of the spot-welded region they have little influence on the strength ofthe spot-welded region in the specimen Additionally a pureshear test was also performed in order to obtain the failureload at a loading angle of 90∘ Three sheets are joined witha spot weld so that only the shear load is applied on thespot weld as shown in Figure 4(b) Cross-sectional shape andhardness profile of the specimen are also depicted in Figure 5
23 Testing Equipment and Conditions In the present experi-ment the servohydraulic high speedmaterial testingmachine[14] shown in Figure 6 was utilized in order to obtainthe dynamic failure loads of the spot weld at intermediatestrain rates The machine has a maximum stroke velocityof 7800mms a maximum load of 30 kN and a maximumdisplacement of 300mm For the dynamic failure test theinstrument thatmeasures the load and the displacementmusthave good response in the dynamic motion since failure tests
4 Advances in Materials Science and Engineering
70
70
35 35
(a)
30
30
120
(b)
Figure 4 Specimens used in the failure test (a) combined loading tests at loading angles of 0∘ 15∘ 30∘ 45∘ 60∘ and 75∘ (b) pure shear testsat loading angle of 90∘
00
500
400
300
100
200
1 2 3 4 5 6 7 8 9 10
Distance (mm)
Har
dnes
s (H
v)
Figure 5 Cross-sectional shape and hardness profile of the specimen
Figure 6 High speed material testing machine
Table 1 Chemical composition of steel sheets tested
Material Chemical composition [wt]C Si Mn P S Al Fe
DP590(thickness 10mm) 0073 0034 175 0075 0005 0038 Bal
Advances in Materials Science and Engineering 5
Table 2 Welding schedule and associated nugget diameter of DP590
MaterialSqueezetime
(cycles)
Weldtime
(cycles)
Holdtime
(cycles)
Weldcurrent(kA)
Weldforce(kN)
Nuggetdiameter(mm)
DP590(thickness 10mm) 20 15 20 78 35 632
Table 3 Dynamic failure loads of a spot weld for DP590 at various loading angles
Failure Load of a spot weld for DP590 10119905 (kN)
Loading angle (∘)Quasi-static Dynamic1 times 10minus5 ms 001ms 01ms 12ms
1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd0∘ 920 908 929 972 980 963 1002 994 1008 1036 1029 102115∘ 847 838 861 881 808 894 923 916 935 943 958 96930∘ 810 822 834 889 877 873 885 906 898 929 923 93645∘ 857 855 873 913 918 926 939 948 943 968 979 95660∘ 1009 988 1013 1048 1076 1063 1074 1086 1092 1112 1138 112375∘ 1266 1242 1247 1316 1308 1323 1359 1347 1376 1418 1392 140390∘ 1688 1715 1692 1791 1802 1768 1828 1862 1845 1901 1874 1889
at intermediate strain rates last only for several millisecondsThe machine equipment is set up with a piezoelectric loadcell of Kistler 9051AThe displacement is acquired by a lineardisplacement transducer (LDT) from Sentech CompanyThetesting fixtures were mounted in the high speed materialtesting machine as shown in Figure 6 Dynamic failure testsat the different tensile speeds of 1times10minus5ms 001ms 01msand 12ms were conducted under seven different loadingconditions until the spot weld failed and the specimenseparated into two components The load and displacementweremeasured simultaneously during each testThe load wasmeasured using the load cell in the testing machine and thedisplacement was calculated from the relative movement ofthe two pull bars
3 Evaluation of Dynamic Effect on the FailureLoad of a Spot Weld
31 Failure Loads with Various Loading Angles and LoadingSpeeds With the testing conditions described in Section 23dynamic failure tests were carried out at seven differentloading angles to evaluate the dynamic impact failure load ofthe spot-welded specimen Figure 7 shows load-displacementcurves for spot-welded DP590 specimens at various loadingangles with different tensile speeds of 1 times 10minus5ms 001ms01ms and 12msThe figure shows that the maximum loaddecreases as the loading angle increases when the loadingangle is less than 30∘ whereas the maximum load increasesas the loading angle increases at the interval from 45∘ to90∘ Figure 8 shows the typical load-displacement curvesfor spot-welded DP590 specimens at the loading angles of0∘ 45∘ and 90∘ with different loading speeds The figureshows that the maximum load for spot welds in DP590 steelsincreases when the imposed strain rate increases When thetensile speeds change from 1 times 10minus5ms which is almost
quasi-static states to 12ms the maximum load for spot-welded DP590 increases by approximately 13 Failure loadsobtained from tests for spot-welded DP590 specimens atvarious loading angles and strain rates were listed in Table 3Figure 9 represents the deformed shapes of the specimensmade of DP590 at the onset of failure at various loadingangles with the tensile speed of 12ms Shear failure modewas observed around the circumferential boundary of thenugget as shown in Figure 9 when the pure axial load actson the spot weld at the loading angle of 0∘ For combinedaxial and shear loading conditions failure is initiated with thelocalized necking in the interface between the HAZ and thebase metal A similar failure mechanismwas also observed inthe quasi-static experimental results [13 15]
32 Dynamic Sensitivity of the Failure Load and FailureContours Failure contours of a spot weld at different tensilespeeds were also constructed by decomposing the failureloadsmeasured in the experiment into two components alongthe axial and shear directionsThese were plotted in the forcedomain as shown in Figure 10 which shows that the failurecontour expands as the tensile speed increases In order toexamine the effect of the tensile speeds on the failure loadof spot welds the axial and shear failure loads were plottedin a logarithmic scale of the tensile speeds as shown inFigure 11 The figure shows that the axial and shear failureload increase as the tensile speeds increase Moreover thedynamic sensitivity can be interpolated in terms of the quasi-static failure load and the logarithm of the tensile speedsDynamic sensitivity of the failure loads at various loadingangles was also investigated The dynamic failure loads atvarious loading angles were normalized by the quasi-staticloads as 119865(V) = 119865(V)119865
0(V119900) where 119865
0(V0) denotes the quasi-
static failure load at a given loading angle The normalizedfailure loads of spot-weldedDP590 specimenswere plotted in
6 Advances in Materials Science and Engineering
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(c)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(d)
Figure 7 Load-displacement curves of spot-welded specimens for DP590 at various loading speeds (a) quasi-static (1 times 10minus5ms) (b)dynamic (001ms) (c) dynamic (01ms) (d) dynamic (12ms)
Figure 12 at various loading angles The figure shows that thetensile speeds have effects on the normalized failure loads fora given loading angle while the normalized failure loads at agiven tensile speed are insensitive to the loading angles whichimplies that the failure loads show similar dynamic sensitivitywith respect to the loading angles
4 Conclusion
In this paper effects of tensile speeds on the failure loadof a DP590 spot weld are evaluated under combined axialand shear loading conditions Dynamic failure tests of spotwelds were conducted at seven different combined loadingconditions in order to obtain the dynamic failure loads of spotwelds at the tensile speed from quasi-static to 12ms Theexperimental results indicated that the failure load decreasesas the loading angle increases when the loading angle is lessthan 30∘ whereas the failure load increases as the loading
Advances in Materials Science and Engineering 7
0 2 4 6 8 10 120
2
4
6
8
10
12Lo
ad (k
N)
Displacement (mm)
12ms01ms
001msQuasi-static
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(c)
Figure 8 Load-displacement curves of spot-welded specimens for DP590 at various loading angles (a) 0∘ (b) 45∘ (c) 90∘
0∘ 30∘15∘
45∘ 75∘60∘
Figure 9 Deformed shape of the specimen made of DP590 spot welds at various loading angles with the tensile speed of 12ms
8 Advances in Materials Science and Engineering
0 2 4 6 8 10 12 14 16 18 200
2
4
6
8
10
12
14
16
18
20
Axial load (kN)
Shea
r loa
d (k
N)
12ms01ms
001msQuasi-static
Figure 10 Dynamic failure contour of the DP590 spot weld with various tensile speeds
001 01 1 100
6
8
10
12
Axi
al fa
ilure
load
(kN
)
Tensile speed (ms)1E minus 5 1E minus 4 1E minus 3
(a)
0
14
16
18
20
Shea
r fai
lure
load
(kN
)
001 01 1 10Tensile speed (ms)
1E minus 5 1E minus 4 1E minus 3
(b)
Figure 11 Dynamic sensitivity of failure loads of DP590 spot weld (a) axial failure load (b) shear failure load
0 15 30 45 60 75 90100
105
110
115
Nor
mal
ized
failu
re lo
ad
001ms
01ms
Loading angle (∘)
12ms
Figure 12 Normalized failure loads of a DP590 spot weld at various loading angles
Advances in Materials Science and Engineering 9
angle increases at the interval from 45∘ to 90∘ Failurecontours of a spot weld at different tensile speeds were alsoconstructed by decomposing the failure loads measured inthe experiment into two components along the axial andshear directions The constructed failure contours indicatethat failure contour expands as the tensile speed increasesThe results also revealed that dynamic sensitivity can beinterpolated in terms of the quasi-static failure load and thelogarithm of the tensile speeds Moreover the failure loadsshow similar dynamic sensitivity with respect to the loadingangles
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] N Farabi D L Chen J Li Y Zhou and S J Dong ldquoMicrostruc-ture and mechanical properties of laser welded DP600 steeljointsrdquo Materials Science and Engineering A vol 527 no 4-5pp 1215ndash1222 2010
[2] N Farabi D L Chen and Y Zhou ldquoMicrostructure andmechanical properties of laser welded dissimilar DP600DP980dual-phase steel jointsrdquo Journal of Alloys and Compounds vol509 no 3 pp 982ndash989 2011
[3] S Zhang ldquoFracturemechanics solutions to spot weldsrdquo Interna-tional Journal of Fracture vol 112 no 3 pp 247ndash274 2001
[4] S Zuniga and SD Sheppard ldquoResistance spotweld failure loadsand modes in overload conditionsrdquo in Fatigue and FractureMechanics ASTM STP 1296 pp 469ndash489 American Society forTesting and Materials West Conshohocken Pa USA 1997
[5] M Marya K Wang L G Hector Jr and X Gayden ldquoTensile-shear forces and fracture modes in single and multiple weldspecimens in dual-phase steelsrdquo Transactions of the ASMEJournal of Manufacturing Science and Engineering vol 128 no1 pp 287ndash298 2006
[6] Y J Chao ldquoUltimate strength and failure mechanism ofresistance spot weld subjected to tensile shear or combinedtensileshear loadsrdquo Journal of Engineering Materials and Tech-nology vol 125 no 2 pp 125ndash132 2003
[7] R S Birch and M Alves ldquoDynamic failure of structural jointsystemsrdquo Thin-Walled Structures vol 36 no 2 pp 137ndash1542000
[8] F Schneider and N Jones ldquoInfluence of spot-weld failureon crushing of thin-walled structural sectionsrdquo InternationalJournal of Mechanical Sciences vol 45 no 12 pp 2061ndash20812003
[9] E Bayraktar D Kaplan C Buirette and M Grumbach ldquoAppli-cation of impact tensile testing to welded thin sheetsrdquo Journal ofMaterials Processing Technology vol 145 no 1 pp 27ndash39 2004
[10] X Sun and M A Khaleel ldquoDynamic strength evaluations forself-piercing rivets and resistance spot welds joining similar anddissimilar metalsrdquo International Journal of Impact Engineeringvol 34 no 10 pp 1668ndash1682 2007
[11] M I Khan M L Kuntz and Y Zhou ldquoEffects of weldmicrostructure on static and impact performance of resistancespot welded joints in advanced high strength steelsrdquo Science andTechnology of Welding and Joining vol 13 no 3 pp 294ndash3042008
[12] N Khandoker and M Takla ldquoTensile strength and failuresimulation of simplified spot weld modelsrdquo Materials andDesign vol 54 pp 323ndash330 2014
[13] J H Song and H Huh ldquoFailure characterization of spot weldsunder combined axialshear loading conditionsrdquo InternationalJournal of Mechanical Sciences vol 53 no 7 pp 513ndash525 2011
[14] H Huh S-B Kim J-H Song and J-H Lim ldquoDynamic tensilecharacteristics of TRIP-type and DP-type steel sheets for anauto-bodyrdquo International Journal ofMechanical Sciences vol 50no 5 pp 918ndash931 2008
[15] S-H Lin J Pan T Tyan and P Prasad ldquoA general failurecriterion for spot welds under combined loading conditionsrdquoInternational Journal of Solids and Structures vol 40 no 21 pp5539ndash5564 2003
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2 Advances in Materials Science and Engineering
Pull bar(lower)
Fixing block
Specimen
Pin-joint
Fixture
Pull bar(upper)
(a)
0∘ 15∘ 30∘
45∘ 60∘ 75∘
(b)
Figure 1 Fixture set with pin-joints for failure tests of a spot weld under combined loading conditions (a) schematic diagram of a fixture(b) fabricated testing fixtures at various loading angles
NuggetHAZ
Base metal
Thick platewith a hole
Thick platewith a hole
Nugget
Specimen
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
Shea
r loa
d (k
N)
Axial load (kN)
0∘
15∘
15∘
30∘
30∘
35∘
25∘
40∘
45∘
45∘50∘
55∘
60∘
60∘65∘
70∘
75∘
75∘80∘
85∘90∘
10∘
20∘
5∘
(b)
Figure 2 Design of specimen to impose the constant ratio of axial and shear loads on the spot weld during tests schematic description of aspecimen with a guide plate (b) loading path acting on the spot weld at various loading angles (FEM results)
an auto-body In order to describe the failure of a spotweld in the crash analysis it is necessary to evaluate thefailure characteristics of a spot weld under impact loadingcondition Birch and Alves [7] conducted dynamic lap-sheartests of spot-weldedmild steels using a servohydraulic testingmachine Schneider and Jones [8] performed dynamic coach-peel tests at a crosshead speed of 08ms Bayraktar et al [9]
investigated dynamic failure loads of spot-welded lap-shearspecimens using a Charpy impact test Their experimentalresults revealed that the dynamic failure load of spot weldsincreases relative to the quasi-static failure load Sun andKhaleel [10] also observed the strain-rate dependent failureload of spot welds in dynamic cross-tension tests Khan etal conducted drop weight test using lab-shear specimen to
Advances in Materials Science and Engineering 3
FS
FN
120601
x998400
z998400
x
z
Fz
120601
Figure 3 Decomposition of the applied load on a spot weld into theaxial and the shear component at the loading angle of 120601
investigate the impact performance of spot welds in advancedhigh strength steels [11] It is however not feasible to performdynamic lap-shear cross-tension and coach-peel tests forconstructing a strain-rate dependent failure criterion thatdescribes the behavior of spot welds under impact loadingconditions because spot welds in automotive components aresubjected to complicated dynamic loading conditions whenthey undergo crashed deformation [12]
In this paper the failure behavior of the DP590 spot weldunder combined loading conditions is investigated underquasi-static and impact loading condition Dynamic failuretests of the spot weld are conducted with seven differentcombined loading conditions at various tensile speeds fromquasi-static to 12ms Dynamic effects on the failure load ofthe spot weld which is critical for structural crashworthinessare examined based on the experimental data
2 Dynamic Failure Tests of a Spot Weld underCombined Loading Conditions
21 Testing Fixtures to Impose Combined Loading Conditionson the Spot Weld In order to impose the combined axialand shear loads on a spot weld specially designed testingfixtures and specimens were adopted in this paper [13] Thetesting fixture shown in Figure 1 contains the pin-joints thateliminate the horizontal force and bending moment Thespecimen shown in Figure 2(a) involves guide plates thatprevent unfavorable rotation of the nugget due to bendingdeformation The testing fixture and specimen ensure acombined loading conditionwith a constant ratio of the shearload to the axial load during the test as shown in Figure 2(b)[13] Therefore as explained in Figure 3 the applied load 119865
119911
can be decomposed into the axial load 119865119873
and the shear
load 119865119878at the nugget region using the simple trigonometric
functions
119865119873= 119865119911cos120601
119865119878= 119865119911sin120601
(1)
Here 119865119873 119865119878 and 120601 denote the axial load the shear load and
the initial inclined angle with respect to the pulling directionrespectivelyThe inclined angle120601 is equal to the loading anglewhich represents the angle between the load application lineand the centerline of the specimen
22 Testing Material and Preparation of Specimen The spotweld of DP590 with the thickness of 10mm is considered inthis paper The chemical compositions are listed in Table 1Prior to spot welding of a specimen the specimen surfacewas wiped with a weak acetone solution using a cloth inorder to remove grease and dirt from its surface Spotwelding was then performed using a static spotprojectionwelding machine The welding schedules shown in Table 2were determined after several trials with the aid of industrystandards to guarantee a button-type failure
The specimen used in the tests is shown in Figure 4(a)To restrict the bending of the region outside the spot weldtwo guide plates made of SPFC590 steel with the thickness of32mm were attached onto the outsides of the specimen inthe following procedure
(1) Two guide plates with a hole at the center are pre-paredThickness and hole diameter of the guide plateare 32mm and 10mm respectively
(2) A guide plate was joined with a steel sheet on one sideusing six points of spot welding around the hole at thecenter of the guide plate
(3) Two pairs of the joined guide plate and the steel sheetwere spot welded to each other through the holes atthe center of guide plates
As the diameter of the hole in the guide plate was 10mmthe six spot weld points that joined the guide plate and thesteel sheet only serve to prevent excessive bending of the spot-welded region they have little influence on the strength ofthe spot-welded region in the specimen Additionally a pureshear test was also performed in order to obtain the failureload at a loading angle of 90∘ Three sheets are joined witha spot weld so that only the shear load is applied on thespot weld as shown in Figure 4(b) Cross-sectional shape andhardness profile of the specimen are also depicted in Figure 5
23 Testing Equipment and Conditions In the present experi-ment the servohydraulic high speedmaterial testingmachine[14] shown in Figure 6 was utilized in order to obtainthe dynamic failure loads of the spot weld at intermediatestrain rates The machine has a maximum stroke velocityof 7800mms a maximum load of 30 kN and a maximumdisplacement of 300mm For the dynamic failure test theinstrument thatmeasures the load and the displacementmusthave good response in the dynamic motion since failure tests
4 Advances in Materials Science and Engineering
70
70
35 35
(a)
30
30
120
(b)
Figure 4 Specimens used in the failure test (a) combined loading tests at loading angles of 0∘ 15∘ 30∘ 45∘ 60∘ and 75∘ (b) pure shear testsat loading angle of 90∘
00
500
400
300
100
200
1 2 3 4 5 6 7 8 9 10
Distance (mm)
Har
dnes
s (H
v)
Figure 5 Cross-sectional shape and hardness profile of the specimen
Figure 6 High speed material testing machine
Table 1 Chemical composition of steel sheets tested
Material Chemical composition [wt]C Si Mn P S Al Fe
DP590(thickness 10mm) 0073 0034 175 0075 0005 0038 Bal
Advances in Materials Science and Engineering 5
Table 2 Welding schedule and associated nugget diameter of DP590
MaterialSqueezetime
(cycles)
Weldtime
(cycles)
Holdtime
(cycles)
Weldcurrent(kA)
Weldforce(kN)
Nuggetdiameter(mm)
DP590(thickness 10mm) 20 15 20 78 35 632
Table 3 Dynamic failure loads of a spot weld for DP590 at various loading angles
Failure Load of a spot weld for DP590 10119905 (kN)
Loading angle (∘)Quasi-static Dynamic1 times 10minus5 ms 001ms 01ms 12ms
1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd0∘ 920 908 929 972 980 963 1002 994 1008 1036 1029 102115∘ 847 838 861 881 808 894 923 916 935 943 958 96930∘ 810 822 834 889 877 873 885 906 898 929 923 93645∘ 857 855 873 913 918 926 939 948 943 968 979 95660∘ 1009 988 1013 1048 1076 1063 1074 1086 1092 1112 1138 112375∘ 1266 1242 1247 1316 1308 1323 1359 1347 1376 1418 1392 140390∘ 1688 1715 1692 1791 1802 1768 1828 1862 1845 1901 1874 1889
at intermediate strain rates last only for several millisecondsThe machine equipment is set up with a piezoelectric loadcell of Kistler 9051AThe displacement is acquired by a lineardisplacement transducer (LDT) from Sentech CompanyThetesting fixtures were mounted in the high speed materialtesting machine as shown in Figure 6 Dynamic failure testsat the different tensile speeds of 1times10minus5ms 001ms 01msand 12ms were conducted under seven different loadingconditions until the spot weld failed and the specimenseparated into two components The load and displacementweremeasured simultaneously during each testThe load wasmeasured using the load cell in the testing machine and thedisplacement was calculated from the relative movement ofthe two pull bars
3 Evaluation of Dynamic Effect on the FailureLoad of a Spot Weld
31 Failure Loads with Various Loading Angles and LoadingSpeeds With the testing conditions described in Section 23dynamic failure tests were carried out at seven differentloading angles to evaluate the dynamic impact failure load ofthe spot-welded specimen Figure 7 shows load-displacementcurves for spot-welded DP590 specimens at various loadingangles with different tensile speeds of 1 times 10minus5ms 001ms01ms and 12msThe figure shows that the maximum loaddecreases as the loading angle increases when the loadingangle is less than 30∘ whereas the maximum load increasesas the loading angle increases at the interval from 45∘ to90∘ Figure 8 shows the typical load-displacement curvesfor spot-welded DP590 specimens at the loading angles of0∘ 45∘ and 90∘ with different loading speeds The figureshows that the maximum load for spot welds in DP590 steelsincreases when the imposed strain rate increases When thetensile speeds change from 1 times 10minus5ms which is almost
quasi-static states to 12ms the maximum load for spot-welded DP590 increases by approximately 13 Failure loadsobtained from tests for spot-welded DP590 specimens atvarious loading angles and strain rates were listed in Table 3Figure 9 represents the deformed shapes of the specimensmade of DP590 at the onset of failure at various loadingangles with the tensile speed of 12ms Shear failure modewas observed around the circumferential boundary of thenugget as shown in Figure 9 when the pure axial load actson the spot weld at the loading angle of 0∘ For combinedaxial and shear loading conditions failure is initiated with thelocalized necking in the interface between the HAZ and thebase metal A similar failure mechanismwas also observed inthe quasi-static experimental results [13 15]
32 Dynamic Sensitivity of the Failure Load and FailureContours Failure contours of a spot weld at different tensilespeeds were also constructed by decomposing the failureloadsmeasured in the experiment into two components alongthe axial and shear directionsThese were plotted in the forcedomain as shown in Figure 10 which shows that the failurecontour expands as the tensile speed increases In order toexamine the effect of the tensile speeds on the failure loadof spot welds the axial and shear failure loads were plottedin a logarithmic scale of the tensile speeds as shown inFigure 11 The figure shows that the axial and shear failureload increase as the tensile speeds increase Moreover thedynamic sensitivity can be interpolated in terms of the quasi-static failure load and the logarithm of the tensile speedsDynamic sensitivity of the failure loads at various loadingangles was also investigated The dynamic failure loads atvarious loading angles were normalized by the quasi-staticloads as 119865(V) = 119865(V)119865
0(V119900) where 119865
0(V0) denotes the quasi-
static failure load at a given loading angle The normalizedfailure loads of spot-weldedDP590 specimenswere plotted in
6 Advances in Materials Science and Engineering
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(c)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(d)
Figure 7 Load-displacement curves of spot-welded specimens for DP590 at various loading speeds (a) quasi-static (1 times 10minus5ms) (b)dynamic (001ms) (c) dynamic (01ms) (d) dynamic (12ms)
Figure 12 at various loading angles The figure shows that thetensile speeds have effects on the normalized failure loads fora given loading angle while the normalized failure loads at agiven tensile speed are insensitive to the loading angles whichimplies that the failure loads show similar dynamic sensitivitywith respect to the loading angles
4 Conclusion
In this paper effects of tensile speeds on the failure loadof a DP590 spot weld are evaluated under combined axialand shear loading conditions Dynamic failure tests of spotwelds were conducted at seven different combined loadingconditions in order to obtain the dynamic failure loads of spotwelds at the tensile speed from quasi-static to 12ms Theexperimental results indicated that the failure load decreasesas the loading angle increases when the loading angle is lessthan 30∘ whereas the failure load increases as the loading
Advances in Materials Science and Engineering 7
0 2 4 6 8 10 120
2
4
6
8
10
12Lo
ad (k
N)
Displacement (mm)
12ms01ms
001msQuasi-static
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(c)
Figure 8 Load-displacement curves of spot-welded specimens for DP590 at various loading angles (a) 0∘ (b) 45∘ (c) 90∘
0∘ 30∘15∘
45∘ 75∘60∘
Figure 9 Deformed shape of the specimen made of DP590 spot welds at various loading angles with the tensile speed of 12ms
8 Advances in Materials Science and Engineering
0 2 4 6 8 10 12 14 16 18 200
2
4
6
8
10
12
14
16
18
20
Axial load (kN)
Shea
r loa
d (k
N)
12ms01ms
001msQuasi-static
Figure 10 Dynamic failure contour of the DP590 spot weld with various tensile speeds
001 01 1 100
6
8
10
12
Axi
al fa
ilure
load
(kN
)
Tensile speed (ms)1E minus 5 1E minus 4 1E minus 3
(a)
0
14
16
18
20
Shea
r fai
lure
load
(kN
)
001 01 1 10Tensile speed (ms)
1E minus 5 1E minus 4 1E minus 3
(b)
Figure 11 Dynamic sensitivity of failure loads of DP590 spot weld (a) axial failure load (b) shear failure load
0 15 30 45 60 75 90100
105
110
115
Nor
mal
ized
failu
re lo
ad
001ms
01ms
Loading angle (∘)
12ms
Figure 12 Normalized failure loads of a DP590 spot weld at various loading angles
Advances in Materials Science and Engineering 9
angle increases at the interval from 45∘ to 90∘ Failurecontours of a spot weld at different tensile speeds were alsoconstructed by decomposing the failure loads measured inthe experiment into two components along the axial andshear directions The constructed failure contours indicatethat failure contour expands as the tensile speed increasesThe results also revealed that dynamic sensitivity can beinterpolated in terms of the quasi-static failure load and thelogarithm of the tensile speeds Moreover the failure loadsshow similar dynamic sensitivity with respect to the loadingangles
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] N Farabi D L Chen J Li Y Zhou and S J Dong ldquoMicrostruc-ture and mechanical properties of laser welded DP600 steeljointsrdquo Materials Science and Engineering A vol 527 no 4-5pp 1215ndash1222 2010
[2] N Farabi D L Chen and Y Zhou ldquoMicrostructure andmechanical properties of laser welded dissimilar DP600DP980dual-phase steel jointsrdquo Journal of Alloys and Compounds vol509 no 3 pp 982ndash989 2011
[3] S Zhang ldquoFracturemechanics solutions to spot weldsrdquo Interna-tional Journal of Fracture vol 112 no 3 pp 247ndash274 2001
[4] S Zuniga and SD Sheppard ldquoResistance spotweld failure loadsand modes in overload conditionsrdquo in Fatigue and FractureMechanics ASTM STP 1296 pp 469ndash489 American Society forTesting and Materials West Conshohocken Pa USA 1997
[5] M Marya K Wang L G Hector Jr and X Gayden ldquoTensile-shear forces and fracture modes in single and multiple weldspecimens in dual-phase steelsrdquo Transactions of the ASMEJournal of Manufacturing Science and Engineering vol 128 no1 pp 287ndash298 2006
[6] Y J Chao ldquoUltimate strength and failure mechanism ofresistance spot weld subjected to tensile shear or combinedtensileshear loadsrdquo Journal of Engineering Materials and Tech-nology vol 125 no 2 pp 125ndash132 2003
[7] R S Birch and M Alves ldquoDynamic failure of structural jointsystemsrdquo Thin-Walled Structures vol 36 no 2 pp 137ndash1542000
[8] F Schneider and N Jones ldquoInfluence of spot-weld failureon crushing of thin-walled structural sectionsrdquo InternationalJournal of Mechanical Sciences vol 45 no 12 pp 2061ndash20812003
[9] E Bayraktar D Kaplan C Buirette and M Grumbach ldquoAppli-cation of impact tensile testing to welded thin sheetsrdquo Journal ofMaterials Processing Technology vol 145 no 1 pp 27ndash39 2004
[10] X Sun and M A Khaleel ldquoDynamic strength evaluations forself-piercing rivets and resistance spot welds joining similar anddissimilar metalsrdquo International Journal of Impact Engineeringvol 34 no 10 pp 1668ndash1682 2007
[11] M I Khan M L Kuntz and Y Zhou ldquoEffects of weldmicrostructure on static and impact performance of resistancespot welded joints in advanced high strength steelsrdquo Science andTechnology of Welding and Joining vol 13 no 3 pp 294ndash3042008
[12] N Khandoker and M Takla ldquoTensile strength and failuresimulation of simplified spot weld modelsrdquo Materials andDesign vol 54 pp 323ndash330 2014
[13] J H Song and H Huh ldquoFailure characterization of spot weldsunder combined axialshear loading conditionsrdquo InternationalJournal of Mechanical Sciences vol 53 no 7 pp 513ndash525 2011
[14] H Huh S-B Kim J-H Song and J-H Lim ldquoDynamic tensilecharacteristics of TRIP-type and DP-type steel sheets for anauto-bodyrdquo International Journal ofMechanical Sciences vol 50no 5 pp 918ndash931 2008
[15] S-H Lin J Pan T Tyan and P Prasad ldquoA general failurecriterion for spot welds under combined loading conditionsrdquoInternational Journal of Solids and Structures vol 40 no 21 pp5539ndash5564 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Nano
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Journal ofNanomaterials
Advances in Materials Science and Engineering 3
FS
FN
120601
x998400
z998400
x
z
Fz
120601
Figure 3 Decomposition of the applied load on a spot weld into theaxial and the shear component at the loading angle of 120601
investigate the impact performance of spot welds in advancedhigh strength steels [11] It is however not feasible to performdynamic lap-shear cross-tension and coach-peel tests forconstructing a strain-rate dependent failure criterion thatdescribes the behavior of spot welds under impact loadingconditions because spot welds in automotive components aresubjected to complicated dynamic loading conditions whenthey undergo crashed deformation [12]
In this paper the failure behavior of the DP590 spot weldunder combined loading conditions is investigated underquasi-static and impact loading condition Dynamic failuretests of the spot weld are conducted with seven differentcombined loading conditions at various tensile speeds fromquasi-static to 12ms Dynamic effects on the failure load ofthe spot weld which is critical for structural crashworthinessare examined based on the experimental data
2 Dynamic Failure Tests of a Spot Weld underCombined Loading Conditions
21 Testing Fixtures to Impose Combined Loading Conditionson the Spot Weld In order to impose the combined axialand shear loads on a spot weld specially designed testingfixtures and specimens were adopted in this paper [13] Thetesting fixture shown in Figure 1 contains the pin-joints thateliminate the horizontal force and bending moment Thespecimen shown in Figure 2(a) involves guide plates thatprevent unfavorable rotation of the nugget due to bendingdeformation The testing fixture and specimen ensure acombined loading conditionwith a constant ratio of the shearload to the axial load during the test as shown in Figure 2(b)[13] Therefore as explained in Figure 3 the applied load 119865
119911
can be decomposed into the axial load 119865119873
and the shear
load 119865119878at the nugget region using the simple trigonometric
functions
119865119873= 119865119911cos120601
119865119878= 119865119911sin120601
(1)
Here 119865119873 119865119878 and 120601 denote the axial load the shear load and
the initial inclined angle with respect to the pulling directionrespectivelyThe inclined angle120601 is equal to the loading anglewhich represents the angle between the load application lineand the centerline of the specimen
22 Testing Material and Preparation of Specimen The spotweld of DP590 with the thickness of 10mm is considered inthis paper The chemical compositions are listed in Table 1Prior to spot welding of a specimen the specimen surfacewas wiped with a weak acetone solution using a cloth inorder to remove grease and dirt from its surface Spotwelding was then performed using a static spotprojectionwelding machine The welding schedules shown in Table 2were determined after several trials with the aid of industrystandards to guarantee a button-type failure
The specimen used in the tests is shown in Figure 4(a)To restrict the bending of the region outside the spot weldtwo guide plates made of SPFC590 steel with the thickness of32mm were attached onto the outsides of the specimen inthe following procedure
(1) Two guide plates with a hole at the center are pre-paredThickness and hole diameter of the guide plateare 32mm and 10mm respectively
(2) A guide plate was joined with a steel sheet on one sideusing six points of spot welding around the hole at thecenter of the guide plate
(3) Two pairs of the joined guide plate and the steel sheetwere spot welded to each other through the holes atthe center of guide plates
As the diameter of the hole in the guide plate was 10mmthe six spot weld points that joined the guide plate and thesteel sheet only serve to prevent excessive bending of the spot-welded region they have little influence on the strength ofthe spot-welded region in the specimen Additionally a pureshear test was also performed in order to obtain the failureload at a loading angle of 90∘ Three sheets are joined witha spot weld so that only the shear load is applied on thespot weld as shown in Figure 4(b) Cross-sectional shape andhardness profile of the specimen are also depicted in Figure 5
23 Testing Equipment and Conditions In the present experi-ment the servohydraulic high speedmaterial testingmachine[14] shown in Figure 6 was utilized in order to obtainthe dynamic failure loads of the spot weld at intermediatestrain rates The machine has a maximum stroke velocityof 7800mms a maximum load of 30 kN and a maximumdisplacement of 300mm For the dynamic failure test theinstrument thatmeasures the load and the displacementmusthave good response in the dynamic motion since failure tests
4 Advances in Materials Science and Engineering
70
70
35 35
(a)
30
30
120
(b)
Figure 4 Specimens used in the failure test (a) combined loading tests at loading angles of 0∘ 15∘ 30∘ 45∘ 60∘ and 75∘ (b) pure shear testsat loading angle of 90∘
00
500
400
300
100
200
1 2 3 4 5 6 7 8 9 10
Distance (mm)
Har
dnes
s (H
v)
Figure 5 Cross-sectional shape and hardness profile of the specimen
Figure 6 High speed material testing machine
Table 1 Chemical composition of steel sheets tested
Material Chemical composition [wt]C Si Mn P S Al Fe
DP590(thickness 10mm) 0073 0034 175 0075 0005 0038 Bal
Advances in Materials Science and Engineering 5
Table 2 Welding schedule and associated nugget diameter of DP590
MaterialSqueezetime
(cycles)
Weldtime
(cycles)
Holdtime
(cycles)
Weldcurrent(kA)
Weldforce(kN)
Nuggetdiameter(mm)
DP590(thickness 10mm) 20 15 20 78 35 632
Table 3 Dynamic failure loads of a spot weld for DP590 at various loading angles
Failure Load of a spot weld for DP590 10119905 (kN)
Loading angle (∘)Quasi-static Dynamic1 times 10minus5 ms 001ms 01ms 12ms
1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd0∘ 920 908 929 972 980 963 1002 994 1008 1036 1029 102115∘ 847 838 861 881 808 894 923 916 935 943 958 96930∘ 810 822 834 889 877 873 885 906 898 929 923 93645∘ 857 855 873 913 918 926 939 948 943 968 979 95660∘ 1009 988 1013 1048 1076 1063 1074 1086 1092 1112 1138 112375∘ 1266 1242 1247 1316 1308 1323 1359 1347 1376 1418 1392 140390∘ 1688 1715 1692 1791 1802 1768 1828 1862 1845 1901 1874 1889
at intermediate strain rates last only for several millisecondsThe machine equipment is set up with a piezoelectric loadcell of Kistler 9051AThe displacement is acquired by a lineardisplacement transducer (LDT) from Sentech CompanyThetesting fixtures were mounted in the high speed materialtesting machine as shown in Figure 6 Dynamic failure testsat the different tensile speeds of 1times10minus5ms 001ms 01msand 12ms were conducted under seven different loadingconditions until the spot weld failed and the specimenseparated into two components The load and displacementweremeasured simultaneously during each testThe load wasmeasured using the load cell in the testing machine and thedisplacement was calculated from the relative movement ofthe two pull bars
3 Evaluation of Dynamic Effect on the FailureLoad of a Spot Weld
31 Failure Loads with Various Loading Angles and LoadingSpeeds With the testing conditions described in Section 23dynamic failure tests were carried out at seven differentloading angles to evaluate the dynamic impact failure load ofthe spot-welded specimen Figure 7 shows load-displacementcurves for spot-welded DP590 specimens at various loadingangles with different tensile speeds of 1 times 10minus5ms 001ms01ms and 12msThe figure shows that the maximum loaddecreases as the loading angle increases when the loadingangle is less than 30∘ whereas the maximum load increasesas the loading angle increases at the interval from 45∘ to90∘ Figure 8 shows the typical load-displacement curvesfor spot-welded DP590 specimens at the loading angles of0∘ 45∘ and 90∘ with different loading speeds The figureshows that the maximum load for spot welds in DP590 steelsincreases when the imposed strain rate increases When thetensile speeds change from 1 times 10minus5ms which is almost
quasi-static states to 12ms the maximum load for spot-welded DP590 increases by approximately 13 Failure loadsobtained from tests for spot-welded DP590 specimens atvarious loading angles and strain rates were listed in Table 3Figure 9 represents the deformed shapes of the specimensmade of DP590 at the onset of failure at various loadingangles with the tensile speed of 12ms Shear failure modewas observed around the circumferential boundary of thenugget as shown in Figure 9 when the pure axial load actson the spot weld at the loading angle of 0∘ For combinedaxial and shear loading conditions failure is initiated with thelocalized necking in the interface between the HAZ and thebase metal A similar failure mechanismwas also observed inthe quasi-static experimental results [13 15]
32 Dynamic Sensitivity of the Failure Load and FailureContours Failure contours of a spot weld at different tensilespeeds were also constructed by decomposing the failureloadsmeasured in the experiment into two components alongthe axial and shear directionsThese were plotted in the forcedomain as shown in Figure 10 which shows that the failurecontour expands as the tensile speed increases In order toexamine the effect of the tensile speeds on the failure loadof spot welds the axial and shear failure loads were plottedin a logarithmic scale of the tensile speeds as shown inFigure 11 The figure shows that the axial and shear failureload increase as the tensile speeds increase Moreover thedynamic sensitivity can be interpolated in terms of the quasi-static failure load and the logarithm of the tensile speedsDynamic sensitivity of the failure loads at various loadingangles was also investigated The dynamic failure loads atvarious loading angles were normalized by the quasi-staticloads as 119865(V) = 119865(V)119865
0(V119900) where 119865
0(V0) denotes the quasi-
static failure load at a given loading angle The normalizedfailure loads of spot-weldedDP590 specimenswere plotted in
6 Advances in Materials Science and Engineering
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(c)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(d)
Figure 7 Load-displacement curves of spot-welded specimens for DP590 at various loading speeds (a) quasi-static (1 times 10minus5ms) (b)dynamic (001ms) (c) dynamic (01ms) (d) dynamic (12ms)
Figure 12 at various loading angles The figure shows that thetensile speeds have effects on the normalized failure loads fora given loading angle while the normalized failure loads at agiven tensile speed are insensitive to the loading angles whichimplies that the failure loads show similar dynamic sensitivitywith respect to the loading angles
4 Conclusion
In this paper effects of tensile speeds on the failure loadof a DP590 spot weld are evaluated under combined axialand shear loading conditions Dynamic failure tests of spotwelds were conducted at seven different combined loadingconditions in order to obtain the dynamic failure loads of spotwelds at the tensile speed from quasi-static to 12ms Theexperimental results indicated that the failure load decreasesas the loading angle increases when the loading angle is lessthan 30∘ whereas the failure load increases as the loading
Advances in Materials Science and Engineering 7
0 2 4 6 8 10 120
2
4
6
8
10
12Lo
ad (k
N)
Displacement (mm)
12ms01ms
001msQuasi-static
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(c)
Figure 8 Load-displacement curves of spot-welded specimens for DP590 at various loading angles (a) 0∘ (b) 45∘ (c) 90∘
0∘ 30∘15∘
45∘ 75∘60∘
Figure 9 Deformed shape of the specimen made of DP590 spot welds at various loading angles with the tensile speed of 12ms
8 Advances in Materials Science and Engineering
0 2 4 6 8 10 12 14 16 18 200
2
4
6
8
10
12
14
16
18
20
Axial load (kN)
Shea
r loa
d (k
N)
12ms01ms
001msQuasi-static
Figure 10 Dynamic failure contour of the DP590 spot weld with various tensile speeds
001 01 1 100
6
8
10
12
Axi
al fa
ilure
load
(kN
)
Tensile speed (ms)1E minus 5 1E minus 4 1E minus 3
(a)
0
14
16
18
20
Shea
r fai
lure
load
(kN
)
001 01 1 10Tensile speed (ms)
1E minus 5 1E minus 4 1E minus 3
(b)
Figure 11 Dynamic sensitivity of failure loads of DP590 spot weld (a) axial failure load (b) shear failure load
0 15 30 45 60 75 90100
105
110
115
Nor
mal
ized
failu
re lo
ad
001ms
01ms
Loading angle (∘)
12ms
Figure 12 Normalized failure loads of a DP590 spot weld at various loading angles
Advances in Materials Science and Engineering 9
angle increases at the interval from 45∘ to 90∘ Failurecontours of a spot weld at different tensile speeds were alsoconstructed by decomposing the failure loads measured inthe experiment into two components along the axial andshear directions The constructed failure contours indicatethat failure contour expands as the tensile speed increasesThe results also revealed that dynamic sensitivity can beinterpolated in terms of the quasi-static failure load and thelogarithm of the tensile speeds Moreover the failure loadsshow similar dynamic sensitivity with respect to the loadingangles
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] N Farabi D L Chen J Li Y Zhou and S J Dong ldquoMicrostruc-ture and mechanical properties of laser welded DP600 steeljointsrdquo Materials Science and Engineering A vol 527 no 4-5pp 1215ndash1222 2010
[2] N Farabi D L Chen and Y Zhou ldquoMicrostructure andmechanical properties of laser welded dissimilar DP600DP980dual-phase steel jointsrdquo Journal of Alloys and Compounds vol509 no 3 pp 982ndash989 2011
[3] S Zhang ldquoFracturemechanics solutions to spot weldsrdquo Interna-tional Journal of Fracture vol 112 no 3 pp 247ndash274 2001
[4] S Zuniga and SD Sheppard ldquoResistance spotweld failure loadsand modes in overload conditionsrdquo in Fatigue and FractureMechanics ASTM STP 1296 pp 469ndash489 American Society forTesting and Materials West Conshohocken Pa USA 1997
[5] M Marya K Wang L G Hector Jr and X Gayden ldquoTensile-shear forces and fracture modes in single and multiple weldspecimens in dual-phase steelsrdquo Transactions of the ASMEJournal of Manufacturing Science and Engineering vol 128 no1 pp 287ndash298 2006
[6] Y J Chao ldquoUltimate strength and failure mechanism ofresistance spot weld subjected to tensile shear or combinedtensileshear loadsrdquo Journal of Engineering Materials and Tech-nology vol 125 no 2 pp 125ndash132 2003
[7] R S Birch and M Alves ldquoDynamic failure of structural jointsystemsrdquo Thin-Walled Structures vol 36 no 2 pp 137ndash1542000
[8] F Schneider and N Jones ldquoInfluence of spot-weld failureon crushing of thin-walled structural sectionsrdquo InternationalJournal of Mechanical Sciences vol 45 no 12 pp 2061ndash20812003
[9] E Bayraktar D Kaplan C Buirette and M Grumbach ldquoAppli-cation of impact tensile testing to welded thin sheetsrdquo Journal ofMaterials Processing Technology vol 145 no 1 pp 27ndash39 2004
[10] X Sun and M A Khaleel ldquoDynamic strength evaluations forself-piercing rivets and resistance spot welds joining similar anddissimilar metalsrdquo International Journal of Impact Engineeringvol 34 no 10 pp 1668ndash1682 2007
[11] M I Khan M L Kuntz and Y Zhou ldquoEffects of weldmicrostructure on static and impact performance of resistancespot welded joints in advanced high strength steelsrdquo Science andTechnology of Welding and Joining vol 13 no 3 pp 294ndash3042008
[12] N Khandoker and M Takla ldquoTensile strength and failuresimulation of simplified spot weld modelsrdquo Materials andDesign vol 54 pp 323ndash330 2014
[13] J H Song and H Huh ldquoFailure characterization of spot weldsunder combined axialshear loading conditionsrdquo InternationalJournal of Mechanical Sciences vol 53 no 7 pp 513ndash525 2011
[14] H Huh S-B Kim J-H Song and J-H Lim ldquoDynamic tensilecharacteristics of TRIP-type and DP-type steel sheets for anauto-bodyrdquo International Journal ofMechanical Sciences vol 50no 5 pp 918ndash931 2008
[15] S-H Lin J Pan T Tyan and P Prasad ldquoA general failurecriterion for spot welds under combined loading conditionsrdquoInternational Journal of Solids and Structures vol 40 no 21 pp5539ndash5564 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
4 Advances in Materials Science and Engineering
70
70
35 35
(a)
30
30
120
(b)
Figure 4 Specimens used in the failure test (a) combined loading tests at loading angles of 0∘ 15∘ 30∘ 45∘ 60∘ and 75∘ (b) pure shear testsat loading angle of 90∘
00
500
400
300
100
200
1 2 3 4 5 6 7 8 9 10
Distance (mm)
Har
dnes
s (H
v)
Figure 5 Cross-sectional shape and hardness profile of the specimen
Figure 6 High speed material testing machine
Table 1 Chemical composition of steel sheets tested
Material Chemical composition [wt]C Si Mn P S Al Fe
DP590(thickness 10mm) 0073 0034 175 0075 0005 0038 Bal
Advances in Materials Science and Engineering 5
Table 2 Welding schedule and associated nugget diameter of DP590
MaterialSqueezetime
(cycles)
Weldtime
(cycles)
Holdtime
(cycles)
Weldcurrent(kA)
Weldforce(kN)
Nuggetdiameter(mm)
DP590(thickness 10mm) 20 15 20 78 35 632
Table 3 Dynamic failure loads of a spot weld for DP590 at various loading angles
Failure Load of a spot weld for DP590 10119905 (kN)
Loading angle (∘)Quasi-static Dynamic1 times 10minus5 ms 001ms 01ms 12ms
1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd0∘ 920 908 929 972 980 963 1002 994 1008 1036 1029 102115∘ 847 838 861 881 808 894 923 916 935 943 958 96930∘ 810 822 834 889 877 873 885 906 898 929 923 93645∘ 857 855 873 913 918 926 939 948 943 968 979 95660∘ 1009 988 1013 1048 1076 1063 1074 1086 1092 1112 1138 112375∘ 1266 1242 1247 1316 1308 1323 1359 1347 1376 1418 1392 140390∘ 1688 1715 1692 1791 1802 1768 1828 1862 1845 1901 1874 1889
at intermediate strain rates last only for several millisecondsThe machine equipment is set up with a piezoelectric loadcell of Kistler 9051AThe displacement is acquired by a lineardisplacement transducer (LDT) from Sentech CompanyThetesting fixtures were mounted in the high speed materialtesting machine as shown in Figure 6 Dynamic failure testsat the different tensile speeds of 1times10minus5ms 001ms 01msand 12ms were conducted under seven different loadingconditions until the spot weld failed and the specimenseparated into two components The load and displacementweremeasured simultaneously during each testThe load wasmeasured using the load cell in the testing machine and thedisplacement was calculated from the relative movement ofthe two pull bars
3 Evaluation of Dynamic Effect on the FailureLoad of a Spot Weld
31 Failure Loads with Various Loading Angles and LoadingSpeeds With the testing conditions described in Section 23dynamic failure tests were carried out at seven differentloading angles to evaluate the dynamic impact failure load ofthe spot-welded specimen Figure 7 shows load-displacementcurves for spot-welded DP590 specimens at various loadingangles with different tensile speeds of 1 times 10minus5ms 001ms01ms and 12msThe figure shows that the maximum loaddecreases as the loading angle increases when the loadingangle is less than 30∘ whereas the maximum load increasesas the loading angle increases at the interval from 45∘ to90∘ Figure 8 shows the typical load-displacement curvesfor spot-welded DP590 specimens at the loading angles of0∘ 45∘ and 90∘ with different loading speeds The figureshows that the maximum load for spot welds in DP590 steelsincreases when the imposed strain rate increases When thetensile speeds change from 1 times 10minus5ms which is almost
quasi-static states to 12ms the maximum load for spot-welded DP590 increases by approximately 13 Failure loadsobtained from tests for spot-welded DP590 specimens atvarious loading angles and strain rates were listed in Table 3Figure 9 represents the deformed shapes of the specimensmade of DP590 at the onset of failure at various loadingangles with the tensile speed of 12ms Shear failure modewas observed around the circumferential boundary of thenugget as shown in Figure 9 when the pure axial load actson the spot weld at the loading angle of 0∘ For combinedaxial and shear loading conditions failure is initiated with thelocalized necking in the interface between the HAZ and thebase metal A similar failure mechanismwas also observed inthe quasi-static experimental results [13 15]
32 Dynamic Sensitivity of the Failure Load and FailureContours Failure contours of a spot weld at different tensilespeeds were also constructed by decomposing the failureloadsmeasured in the experiment into two components alongthe axial and shear directionsThese were plotted in the forcedomain as shown in Figure 10 which shows that the failurecontour expands as the tensile speed increases In order toexamine the effect of the tensile speeds on the failure loadof spot welds the axial and shear failure loads were plottedin a logarithmic scale of the tensile speeds as shown inFigure 11 The figure shows that the axial and shear failureload increase as the tensile speeds increase Moreover thedynamic sensitivity can be interpolated in terms of the quasi-static failure load and the logarithm of the tensile speedsDynamic sensitivity of the failure loads at various loadingangles was also investigated The dynamic failure loads atvarious loading angles were normalized by the quasi-staticloads as 119865(V) = 119865(V)119865
0(V119900) where 119865
0(V0) denotes the quasi-
static failure load at a given loading angle The normalizedfailure loads of spot-weldedDP590 specimenswere plotted in
6 Advances in Materials Science and Engineering
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(c)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(d)
Figure 7 Load-displacement curves of spot-welded specimens for DP590 at various loading speeds (a) quasi-static (1 times 10minus5ms) (b)dynamic (001ms) (c) dynamic (01ms) (d) dynamic (12ms)
Figure 12 at various loading angles The figure shows that thetensile speeds have effects on the normalized failure loads fora given loading angle while the normalized failure loads at agiven tensile speed are insensitive to the loading angles whichimplies that the failure loads show similar dynamic sensitivitywith respect to the loading angles
4 Conclusion
In this paper effects of tensile speeds on the failure loadof a DP590 spot weld are evaluated under combined axialand shear loading conditions Dynamic failure tests of spotwelds were conducted at seven different combined loadingconditions in order to obtain the dynamic failure loads of spotwelds at the tensile speed from quasi-static to 12ms Theexperimental results indicated that the failure load decreasesas the loading angle increases when the loading angle is lessthan 30∘ whereas the failure load increases as the loading
Advances in Materials Science and Engineering 7
0 2 4 6 8 10 120
2
4
6
8
10
12Lo
ad (k
N)
Displacement (mm)
12ms01ms
001msQuasi-static
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(c)
Figure 8 Load-displacement curves of spot-welded specimens for DP590 at various loading angles (a) 0∘ (b) 45∘ (c) 90∘
0∘ 30∘15∘
45∘ 75∘60∘
Figure 9 Deformed shape of the specimen made of DP590 spot welds at various loading angles with the tensile speed of 12ms
8 Advances in Materials Science and Engineering
0 2 4 6 8 10 12 14 16 18 200
2
4
6
8
10
12
14
16
18
20
Axial load (kN)
Shea
r loa
d (k
N)
12ms01ms
001msQuasi-static
Figure 10 Dynamic failure contour of the DP590 spot weld with various tensile speeds
001 01 1 100
6
8
10
12
Axi
al fa
ilure
load
(kN
)
Tensile speed (ms)1E minus 5 1E minus 4 1E minus 3
(a)
0
14
16
18
20
Shea
r fai
lure
load
(kN
)
001 01 1 10Tensile speed (ms)
1E minus 5 1E minus 4 1E minus 3
(b)
Figure 11 Dynamic sensitivity of failure loads of DP590 spot weld (a) axial failure load (b) shear failure load
0 15 30 45 60 75 90100
105
110
115
Nor
mal
ized
failu
re lo
ad
001ms
01ms
Loading angle (∘)
12ms
Figure 12 Normalized failure loads of a DP590 spot weld at various loading angles
Advances in Materials Science and Engineering 9
angle increases at the interval from 45∘ to 90∘ Failurecontours of a spot weld at different tensile speeds were alsoconstructed by decomposing the failure loads measured inthe experiment into two components along the axial andshear directions The constructed failure contours indicatethat failure contour expands as the tensile speed increasesThe results also revealed that dynamic sensitivity can beinterpolated in terms of the quasi-static failure load and thelogarithm of the tensile speeds Moreover the failure loadsshow similar dynamic sensitivity with respect to the loadingangles
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] N Farabi D L Chen J Li Y Zhou and S J Dong ldquoMicrostruc-ture and mechanical properties of laser welded DP600 steeljointsrdquo Materials Science and Engineering A vol 527 no 4-5pp 1215ndash1222 2010
[2] N Farabi D L Chen and Y Zhou ldquoMicrostructure andmechanical properties of laser welded dissimilar DP600DP980dual-phase steel jointsrdquo Journal of Alloys and Compounds vol509 no 3 pp 982ndash989 2011
[3] S Zhang ldquoFracturemechanics solutions to spot weldsrdquo Interna-tional Journal of Fracture vol 112 no 3 pp 247ndash274 2001
[4] S Zuniga and SD Sheppard ldquoResistance spotweld failure loadsand modes in overload conditionsrdquo in Fatigue and FractureMechanics ASTM STP 1296 pp 469ndash489 American Society forTesting and Materials West Conshohocken Pa USA 1997
[5] M Marya K Wang L G Hector Jr and X Gayden ldquoTensile-shear forces and fracture modes in single and multiple weldspecimens in dual-phase steelsrdquo Transactions of the ASMEJournal of Manufacturing Science and Engineering vol 128 no1 pp 287ndash298 2006
[6] Y J Chao ldquoUltimate strength and failure mechanism ofresistance spot weld subjected to tensile shear or combinedtensileshear loadsrdquo Journal of Engineering Materials and Tech-nology vol 125 no 2 pp 125ndash132 2003
[7] R S Birch and M Alves ldquoDynamic failure of structural jointsystemsrdquo Thin-Walled Structures vol 36 no 2 pp 137ndash1542000
[8] F Schneider and N Jones ldquoInfluence of spot-weld failureon crushing of thin-walled structural sectionsrdquo InternationalJournal of Mechanical Sciences vol 45 no 12 pp 2061ndash20812003
[9] E Bayraktar D Kaplan C Buirette and M Grumbach ldquoAppli-cation of impact tensile testing to welded thin sheetsrdquo Journal ofMaterials Processing Technology vol 145 no 1 pp 27ndash39 2004
[10] X Sun and M A Khaleel ldquoDynamic strength evaluations forself-piercing rivets and resistance spot welds joining similar anddissimilar metalsrdquo International Journal of Impact Engineeringvol 34 no 10 pp 1668ndash1682 2007
[11] M I Khan M L Kuntz and Y Zhou ldquoEffects of weldmicrostructure on static and impact performance of resistancespot welded joints in advanced high strength steelsrdquo Science andTechnology of Welding and Joining vol 13 no 3 pp 294ndash3042008
[12] N Khandoker and M Takla ldquoTensile strength and failuresimulation of simplified spot weld modelsrdquo Materials andDesign vol 54 pp 323ndash330 2014
[13] J H Song and H Huh ldquoFailure characterization of spot weldsunder combined axialshear loading conditionsrdquo InternationalJournal of Mechanical Sciences vol 53 no 7 pp 513ndash525 2011
[14] H Huh S-B Kim J-H Song and J-H Lim ldquoDynamic tensilecharacteristics of TRIP-type and DP-type steel sheets for anauto-bodyrdquo International Journal ofMechanical Sciences vol 50no 5 pp 918ndash931 2008
[15] S-H Lin J Pan T Tyan and P Prasad ldquoA general failurecriterion for spot welds under combined loading conditionsrdquoInternational Journal of Solids and Structures vol 40 no 21 pp5539ndash5564 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Advances in Materials Science and Engineering 5
Table 2 Welding schedule and associated nugget diameter of DP590
MaterialSqueezetime
(cycles)
Weldtime
(cycles)
Holdtime
(cycles)
Weldcurrent(kA)
Weldforce(kN)
Nuggetdiameter(mm)
DP590(thickness 10mm) 20 15 20 78 35 632
Table 3 Dynamic failure loads of a spot weld for DP590 at various loading angles
Failure Load of a spot weld for DP590 10119905 (kN)
Loading angle (∘)Quasi-static Dynamic1 times 10minus5 ms 001ms 01ms 12ms
1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd0∘ 920 908 929 972 980 963 1002 994 1008 1036 1029 102115∘ 847 838 861 881 808 894 923 916 935 943 958 96930∘ 810 822 834 889 877 873 885 906 898 929 923 93645∘ 857 855 873 913 918 926 939 948 943 968 979 95660∘ 1009 988 1013 1048 1076 1063 1074 1086 1092 1112 1138 112375∘ 1266 1242 1247 1316 1308 1323 1359 1347 1376 1418 1392 140390∘ 1688 1715 1692 1791 1802 1768 1828 1862 1845 1901 1874 1889
at intermediate strain rates last only for several millisecondsThe machine equipment is set up with a piezoelectric loadcell of Kistler 9051AThe displacement is acquired by a lineardisplacement transducer (LDT) from Sentech CompanyThetesting fixtures were mounted in the high speed materialtesting machine as shown in Figure 6 Dynamic failure testsat the different tensile speeds of 1times10minus5ms 001ms 01msand 12ms were conducted under seven different loadingconditions until the spot weld failed and the specimenseparated into two components The load and displacementweremeasured simultaneously during each testThe load wasmeasured using the load cell in the testing machine and thedisplacement was calculated from the relative movement ofthe two pull bars
3 Evaluation of Dynamic Effect on the FailureLoad of a Spot Weld
31 Failure Loads with Various Loading Angles and LoadingSpeeds With the testing conditions described in Section 23dynamic failure tests were carried out at seven differentloading angles to evaluate the dynamic impact failure load ofthe spot-welded specimen Figure 7 shows load-displacementcurves for spot-welded DP590 specimens at various loadingangles with different tensile speeds of 1 times 10minus5ms 001ms01ms and 12msThe figure shows that the maximum loaddecreases as the loading angle increases when the loadingangle is less than 30∘ whereas the maximum load increasesas the loading angle increases at the interval from 45∘ to90∘ Figure 8 shows the typical load-displacement curvesfor spot-welded DP590 specimens at the loading angles of0∘ 45∘ and 90∘ with different loading speeds The figureshows that the maximum load for spot welds in DP590 steelsincreases when the imposed strain rate increases When thetensile speeds change from 1 times 10minus5ms which is almost
quasi-static states to 12ms the maximum load for spot-welded DP590 increases by approximately 13 Failure loadsobtained from tests for spot-welded DP590 specimens atvarious loading angles and strain rates were listed in Table 3Figure 9 represents the deformed shapes of the specimensmade of DP590 at the onset of failure at various loadingangles with the tensile speed of 12ms Shear failure modewas observed around the circumferential boundary of thenugget as shown in Figure 9 when the pure axial load actson the spot weld at the loading angle of 0∘ For combinedaxial and shear loading conditions failure is initiated with thelocalized necking in the interface between the HAZ and thebase metal A similar failure mechanismwas also observed inthe quasi-static experimental results [13 15]
32 Dynamic Sensitivity of the Failure Load and FailureContours Failure contours of a spot weld at different tensilespeeds were also constructed by decomposing the failureloadsmeasured in the experiment into two components alongthe axial and shear directionsThese were plotted in the forcedomain as shown in Figure 10 which shows that the failurecontour expands as the tensile speed increases In order toexamine the effect of the tensile speeds on the failure loadof spot welds the axial and shear failure loads were plottedin a logarithmic scale of the tensile speeds as shown inFigure 11 The figure shows that the axial and shear failureload increase as the tensile speeds increase Moreover thedynamic sensitivity can be interpolated in terms of the quasi-static failure load and the logarithm of the tensile speedsDynamic sensitivity of the failure loads at various loadingangles was also investigated The dynamic failure loads atvarious loading angles were normalized by the quasi-staticloads as 119865(V) = 119865(V)119865
0(V119900) where 119865
0(V0) denotes the quasi-
static failure load at a given loading angle The normalizedfailure loads of spot-weldedDP590 specimenswere plotted in
6 Advances in Materials Science and Engineering
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(c)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(d)
Figure 7 Load-displacement curves of spot-welded specimens for DP590 at various loading speeds (a) quasi-static (1 times 10minus5ms) (b)dynamic (001ms) (c) dynamic (01ms) (d) dynamic (12ms)
Figure 12 at various loading angles The figure shows that thetensile speeds have effects on the normalized failure loads fora given loading angle while the normalized failure loads at agiven tensile speed are insensitive to the loading angles whichimplies that the failure loads show similar dynamic sensitivitywith respect to the loading angles
4 Conclusion
In this paper effects of tensile speeds on the failure loadof a DP590 spot weld are evaluated under combined axialand shear loading conditions Dynamic failure tests of spotwelds were conducted at seven different combined loadingconditions in order to obtain the dynamic failure loads of spotwelds at the tensile speed from quasi-static to 12ms Theexperimental results indicated that the failure load decreasesas the loading angle increases when the loading angle is lessthan 30∘ whereas the failure load increases as the loading
Advances in Materials Science and Engineering 7
0 2 4 6 8 10 120
2
4
6
8
10
12Lo
ad (k
N)
Displacement (mm)
12ms01ms
001msQuasi-static
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(c)
Figure 8 Load-displacement curves of spot-welded specimens for DP590 at various loading angles (a) 0∘ (b) 45∘ (c) 90∘
0∘ 30∘15∘
45∘ 75∘60∘
Figure 9 Deformed shape of the specimen made of DP590 spot welds at various loading angles with the tensile speed of 12ms
8 Advances in Materials Science and Engineering
0 2 4 6 8 10 12 14 16 18 200
2
4
6
8
10
12
14
16
18
20
Axial load (kN)
Shea
r loa
d (k
N)
12ms01ms
001msQuasi-static
Figure 10 Dynamic failure contour of the DP590 spot weld with various tensile speeds
001 01 1 100
6
8
10
12
Axi
al fa
ilure
load
(kN
)
Tensile speed (ms)1E minus 5 1E minus 4 1E minus 3
(a)
0
14
16
18
20
Shea
r fai
lure
load
(kN
)
001 01 1 10Tensile speed (ms)
1E minus 5 1E minus 4 1E minus 3
(b)
Figure 11 Dynamic sensitivity of failure loads of DP590 spot weld (a) axial failure load (b) shear failure load
0 15 30 45 60 75 90100
105
110
115
Nor
mal
ized
failu
re lo
ad
001ms
01ms
Loading angle (∘)
12ms
Figure 12 Normalized failure loads of a DP590 spot weld at various loading angles
Advances in Materials Science and Engineering 9
angle increases at the interval from 45∘ to 90∘ Failurecontours of a spot weld at different tensile speeds were alsoconstructed by decomposing the failure loads measured inthe experiment into two components along the axial andshear directions The constructed failure contours indicatethat failure contour expands as the tensile speed increasesThe results also revealed that dynamic sensitivity can beinterpolated in terms of the quasi-static failure load and thelogarithm of the tensile speeds Moreover the failure loadsshow similar dynamic sensitivity with respect to the loadingangles
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] N Farabi D L Chen J Li Y Zhou and S J Dong ldquoMicrostruc-ture and mechanical properties of laser welded DP600 steeljointsrdquo Materials Science and Engineering A vol 527 no 4-5pp 1215ndash1222 2010
[2] N Farabi D L Chen and Y Zhou ldquoMicrostructure andmechanical properties of laser welded dissimilar DP600DP980dual-phase steel jointsrdquo Journal of Alloys and Compounds vol509 no 3 pp 982ndash989 2011
[3] S Zhang ldquoFracturemechanics solutions to spot weldsrdquo Interna-tional Journal of Fracture vol 112 no 3 pp 247ndash274 2001
[4] S Zuniga and SD Sheppard ldquoResistance spotweld failure loadsand modes in overload conditionsrdquo in Fatigue and FractureMechanics ASTM STP 1296 pp 469ndash489 American Society forTesting and Materials West Conshohocken Pa USA 1997
[5] M Marya K Wang L G Hector Jr and X Gayden ldquoTensile-shear forces and fracture modes in single and multiple weldspecimens in dual-phase steelsrdquo Transactions of the ASMEJournal of Manufacturing Science and Engineering vol 128 no1 pp 287ndash298 2006
[6] Y J Chao ldquoUltimate strength and failure mechanism ofresistance spot weld subjected to tensile shear or combinedtensileshear loadsrdquo Journal of Engineering Materials and Tech-nology vol 125 no 2 pp 125ndash132 2003
[7] R S Birch and M Alves ldquoDynamic failure of structural jointsystemsrdquo Thin-Walled Structures vol 36 no 2 pp 137ndash1542000
[8] F Schneider and N Jones ldquoInfluence of spot-weld failureon crushing of thin-walled structural sectionsrdquo InternationalJournal of Mechanical Sciences vol 45 no 12 pp 2061ndash20812003
[9] E Bayraktar D Kaplan C Buirette and M Grumbach ldquoAppli-cation of impact tensile testing to welded thin sheetsrdquo Journal ofMaterials Processing Technology vol 145 no 1 pp 27ndash39 2004
[10] X Sun and M A Khaleel ldquoDynamic strength evaluations forself-piercing rivets and resistance spot welds joining similar anddissimilar metalsrdquo International Journal of Impact Engineeringvol 34 no 10 pp 1668ndash1682 2007
[11] M I Khan M L Kuntz and Y Zhou ldquoEffects of weldmicrostructure on static and impact performance of resistancespot welded joints in advanced high strength steelsrdquo Science andTechnology of Welding and Joining vol 13 no 3 pp 294ndash3042008
[12] N Khandoker and M Takla ldquoTensile strength and failuresimulation of simplified spot weld modelsrdquo Materials andDesign vol 54 pp 323ndash330 2014
[13] J H Song and H Huh ldquoFailure characterization of spot weldsunder combined axialshear loading conditionsrdquo InternationalJournal of Mechanical Sciences vol 53 no 7 pp 513ndash525 2011
[14] H Huh S-B Kim J-H Song and J-H Lim ldquoDynamic tensilecharacteristics of TRIP-type and DP-type steel sheets for anauto-bodyrdquo International Journal ofMechanical Sciences vol 50no 5 pp 918ndash931 2008
[15] S-H Lin J Pan T Tyan and P Prasad ldquoA general failurecriterion for spot welds under combined loading conditionsrdquoInternational Journal of Solids and Structures vol 40 no 21 pp5539ndash5564 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
6 Advances in Materials Science and Engineering
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(c)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20Lo
ad (k
N)
Displacement (mm)
0∘
15∘
30∘
45∘
60∘
75∘
90∘
(d)
Figure 7 Load-displacement curves of spot-welded specimens for DP590 at various loading speeds (a) quasi-static (1 times 10minus5ms) (b)dynamic (001ms) (c) dynamic (01ms) (d) dynamic (12ms)
Figure 12 at various loading angles The figure shows that thetensile speeds have effects on the normalized failure loads fora given loading angle while the normalized failure loads at agiven tensile speed are insensitive to the loading angles whichimplies that the failure loads show similar dynamic sensitivitywith respect to the loading angles
4 Conclusion
In this paper effects of tensile speeds on the failure loadof a DP590 spot weld are evaluated under combined axialand shear loading conditions Dynamic failure tests of spotwelds were conducted at seven different combined loadingconditions in order to obtain the dynamic failure loads of spotwelds at the tensile speed from quasi-static to 12ms Theexperimental results indicated that the failure load decreasesas the loading angle increases when the loading angle is lessthan 30∘ whereas the failure load increases as the loading
Advances in Materials Science and Engineering 7
0 2 4 6 8 10 120
2
4
6
8
10
12Lo
ad (k
N)
Displacement (mm)
12ms01ms
001msQuasi-static
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(c)
Figure 8 Load-displacement curves of spot-welded specimens for DP590 at various loading angles (a) 0∘ (b) 45∘ (c) 90∘
0∘ 30∘15∘
45∘ 75∘60∘
Figure 9 Deformed shape of the specimen made of DP590 spot welds at various loading angles with the tensile speed of 12ms
8 Advances in Materials Science and Engineering
0 2 4 6 8 10 12 14 16 18 200
2
4
6
8
10
12
14
16
18
20
Axial load (kN)
Shea
r loa
d (k
N)
12ms01ms
001msQuasi-static
Figure 10 Dynamic failure contour of the DP590 spot weld with various tensile speeds
001 01 1 100
6
8
10
12
Axi
al fa
ilure
load
(kN
)
Tensile speed (ms)1E minus 5 1E minus 4 1E minus 3
(a)
0
14
16
18
20
Shea
r fai
lure
load
(kN
)
001 01 1 10Tensile speed (ms)
1E minus 5 1E minus 4 1E minus 3
(b)
Figure 11 Dynamic sensitivity of failure loads of DP590 spot weld (a) axial failure load (b) shear failure load
0 15 30 45 60 75 90100
105
110
115
Nor
mal
ized
failu
re lo
ad
001ms
01ms
Loading angle (∘)
12ms
Figure 12 Normalized failure loads of a DP590 spot weld at various loading angles
Advances in Materials Science and Engineering 9
angle increases at the interval from 45∘ to 90∘ Failurecontours of a spot weld at different tensile speeds were alsoconstructed by decomposing the failure loads measured inthe experiment into two components along the axial andshear directions The constructed failure contours indicatethat failure contour expands as the tensile speed increasesThe results also revealed that dynamic sensitivity can beinterpolated in terms of the quasi-static failure load and thelogarithm of the tensile speeds Moreover the failure loadsshow similar dynamic sensitivity with respect to the loadingangles
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] N Farabi D L Chen J Li Y Zhou and S J Dong ldquoMicrostruc-ture and mechanical properties of laser welded DP600 steeljointsrdquo Materials Science and Engineering A vol 527 no 4-5pp 1215ndash1222 2010
[2] N Farabi D L Chen and Y Zhou ldquoMicrostructure andmechanical properties of laser welded dissimilar DP600DP980dual-phase steel jointsrdquo Journal of Alloys and Compounds vol509 no 3 pp 982ndash989 2011
[3] S Zhang ldquoFracturemechanics solutions to spot weldsrdquo Interna-tional Journal of Fracture vol 112 no 3 pp 247ndash274 2001
[4] S Zuniga and SD Sheppard ldquoResistance spotweld failure loadsand modes in overload conditionsrdquo in Fatigue and FractureMechanics ASTM STP 1296 pp 469ndash489 American Society forTesting and Materials West Conshohocken Pa USA 1997
[5] M Marya K Wang L G Hector Jr and X Gayden ldquoTensile-shear forces and fracture modes in single and multiple weldspecimens in dual-phase steelsrdquo Transactions of the ASMEJournal of Manufacturing Science and Engineering vol 128 no1 pp 287ndash298 2006
[6] Y J Chao ldquoUltimate strength and failure mechanism ofresistance spot weld subjected to tensile shear or combinedtensileshear loadsrdquo Journal of Engineering Materials and Tech-nology vol 125 no 2 pp 125ndash132 2003
[7] R S Birch and M Alves ldquoDynamic failure of structural jointsystemsrdquo Thin-Walled Structures vol 36 no 2 pp 137ndash1542000
[8] F Schneider and N Jones ldquoInfluence of spot-weld failureon crushing of thin-walled structural sectionsrdquo InternationalJournal of Mechanical Sciences vol 45 no 12 pp 2061ndash20812003
[9] E Bayraktar D Kaplan C Buirette and M Grumbach ldquoAppli-cation of impact tensile testing to welded thin sheetsrdquo Journal ofMaterials Processing Technology vol 145 no 1 pp 27ndash39 2004
[10] X Sun and M A Khaleel ldquoDynamic strength evaluations forself-piercing rivets and resistance spot welds joining similar anddissimilar metalsrdquo International Journal of Impact Engineeringvol 34 no 10 pp 1668ndash1682 2007
[11] M I Khan M L Kuntz and Y Zhou ldquoEffects of weldmicrostructure on static and impact performance of resistancespot welded joints in advanced high strength steelsrdquo Science andTechnology of Welding and Joining vol 13 no 3 pp 294ndash3042008
[12] N Khandoker and M Takla ldquoTensile strength and failuresimulation of simplified spot weld modelsrdquo Materials andDesign vol 54 pp 323ndash330 2014
[13] J H Song and H Huh ldquoFailure characterization of spot weldsunder combined axialshear loading conditionsrdquo InternationalJournal of Mechanical Sciences vol 53 no 7 pp 513ndash525 2011
[14] H Huh S-B Kim J-H Song and J-H Lim ldquoDynamic tensilecharacteristics of TRIP-type and DP-type steel sheets for anauto-bodyrdquo International Journal ofMechanical Sciences vol 50no 5 pp 918ndash931 2008
[15] S-H Lin J Pan T Tyan and P Prasad ldquoA general failurecriterion for spot welds under combined loading conditionsrdquoInternational Journal of Solids and Structures vol 40 no 21 pp5539ndash5564 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Advances in Materials Science and Engineering 7
0 2 4 6 8 10 120
2
4
6
8
10
12Lo
ad (k
N)
Displacement (mm)
12ms01ms
001msQuasi-static
(a)
0 2 4 6 8 10 120
2
4
6
8
10
12
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(b)
0 2 4 6 8 10 120
2
4
6
8
10
12
14
16
18
20
Load
(kN
)
Displacement (mm)
12ms01ms
001msQuasi-static
(c)
Figure 8 Load-displacement curves of spot-welded specimens for DP590 at various loading angles (a) 0∘ (b) 45∘ (c) 90∘
0∘ 30∘15∘
45∘ 75∘60∘
Figure 9 Deformed shape of the specimen made of DP590 spot welds at various loading angles with the tensile speed of 12ms
8 Advances in Materials Science and Engineering
0 2 4 6 8 10 12 14 16 18 200
2
4
6
8
10
12
14
16
18
20
Axial load (kN)
Shea
r loa
d (k
N)
12ms01ms
001msQuasi-static
Figure 10 Dynamic failure contour of the DP590 spot weld with various tensile speeds
001 01 1 100
6
8
10
12
Axi
al fa
ilure
load
(kN
)
Tensile speed (ms)1E minus 5 1E minus 4 1E minus 3
(a)
0
14
16
18
20
Shea
r fai
lure
load
(kN
)
001 01 1 10Tensile speed (ms)
1E minus 5 1E minus 4 1E minus 3
(b)
Figure 11 Dynamic sensitivity of failure loads of DP590 spot weld (a) axial failure load (b) shear failure load
0 15 30 45 60 75 90100
105
110
115
Nor
mal
ized
failu
re lo
ad
001ms
01ms
Loading angle (∘)
12ms
Figure 12 Normalized failure loads of a DP590 spot weld at various loading angles
Advances in Materials Science and Engineering 9
angle increases at the interval from 45∘ to 90∘ Failurecontours of a spot weld at different tensile speeds were alsoconstructed by decomposing the failure loads measured inthe experiment into two components along the axial andshear directions The constructed failure contours indicatethat failure contour expands as the tensile speed increasesThe results also revealed that dynamic sensitivity can beinterpolated in terms of the quasi-static failure load and thelogarithm of the tensile speeds Moreover the failure loadsshow similar dynamic sensitivity with respect to the loadingangles
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] N Farabi D L Chen J Li Y Zhou and S J Dong ldquoMicrostruc-ture and mechanical properties of laser welded DP600 steeljointsrdquo Materials Science and Engineering A vol 527 no 4-5pp 1215ndash1222 2010
[2] N Farabi D L Chen and Y Zhou ldquoMicrostructure andmechanical properties of laser welded dissimilar DP600DP980dual-phase steel jointsrdquo Journal of Alloys and Compounds vol509 no 3 pp 982ndash989 2011
[3] S Zhang ldquoFracturemechanics solutions to spot weldsrdquo Interna-tional Journal of Fracture vol 112 no 3 pp 247ndash274 2001
[4] S Zuniga and SD Sheppard ldquoResistance spotweld failure loadsand modes in overload conditionsrdquo in Fatigue and FractureMechanics ASTM STP 1296 pp 469ndash489 American Society forTesting and Materials West Conshohocken Pa USA 1997
[5] M Marya K Wang L G Hector Jr and X Gayden ldquoTensile-shear forces and fracture modes in single and multiple weldspecimens in dual-phase steelsrdquo Transactions of the ASMEJournal of Manufacturing Science and Engineering vol 128 no1 pp 287ndash298 2006
[6] Y J Chao ldquoUltimate strength and failure mechanism ofresistance spot weld subjected to tensile shear or combinedtensileshear loadsrdquo Journal of Engineering Materials and Tech-nology vol 125 no 2 pp 125ndash132 2003
[7] R S Birch and M Alves ldquoDynamic failure of structural jointsystemsrdquo Thin-Walled Structures vol 36 no 2 pp 137ndash1542000
[8] F Schneider and N Jones ldquoInfluence of spot-weld failureon crushing of thin-walled structural sectionsrdquo InternationalJournal of Mechanical Sciences vol 45 no 12 pp 2061ndash20812003
[9] E Bayraktar D Kaplan C Buirette and M Grumbach ldquoAppli-cation of impact tensile testing to welded thin sheetsrdquo Journal ofMaterials Processing Technology vol 145 no 1 pp 27ndash39 2004
[10] X Sun and M A Khaleel ldquoDynamic strength evaluations forself-piercing rivets and resistance spot welds joining similar anddissimilar metalsrdquo International Journal of Impact Engineeringvol 34 no 10 pp 1668ndash1682 2007
[11] M I Khan M L Kuntz and Y Zhou ldquoEffects of weldmicrostructure on static and impact performance of resistancespot welded joints in advanced high strength steelsrdquo Science andTechnology of Welding and Joining vol 13 no 3 pp 294ndash3042008
[12] N Khandoker and M Takla ldquoTensile strength and failuresimulation of simplified spot weld modelsrdquo Materials andDesign vol 54 pp 323ndash330 2014
[13] J H Song and H Huh ldquoFailure characterization of spot weldsunder combined axialshear loading conditionsrdquo InternationalJournal of Mechanical Sciences vol 53 no 7 pp 513ndash525 2011
[14] H Huh S-B Kim J-H Song and J-H Lim ldquoDynamic tensilecharacteristics of TRIP-type and DP-type steel sheets for anauto-bodyrdquo International Journal ofMechanical Sciences vol 50no 5 pp 918ndash931 2008
[15] S-H Lin J Pan T Tyan and P Prasad ldquoA general failurecriterion for spot welds under combined loading conditionsrdquoInternational Journal of Solids and Structures vol 40 no 21 pp5539ndash5564 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
8 Advances in Materials Science and Engineering
0 2 4 6 8 10 12 14 16 18 200
2
4
6
8
10
12
14
16
18
20
Axial load (kN)
Shea
r loa
d (k
N)
12ms01ms
001msQuasi-static
Figure 10 Dynamic failure contour of the DP590 spot weld with various tensile speeds
001 01 1 100
6
8
10
12
Axi
al fa
ilure
load
(kN
)
Tensile speed (ms)1E minus 5 1E minus 4 1E minus 3
(a)
0
14
16
18
20
Shea
r fai
lure
load
(kN
)
001 01 1 10Tensile speed (ms)
1E minus 5 1E minus 4 1E minus 3
(b)
Figure 11 Dynamic sensitivity of failure loads of DP590 spot weld (a) axial failure load (b) shear failure load
0 15 30 45 60 75 90100
105
110
115
Nor
mal
ized
failu
re lo
ad
001ms
01ms
Loading angle (∘)
12ms
Figure 12 Normalized failure loads of a DP590 spot weld at various loading angles
Advances in Materials Science and Engineering 9
angle increases at the interval from 45∘ to 90∘ Failurecontours of a spot weld at different tensile speeds were alsoconstructed by decomposing the failure loads measured inthe experiment into two components along the axial andshear directions The constructed failure contours indicatethat failure contour expands as the tensile speed increasesThe results also revealed that dynamic sensitivity can beinterpolated in terms of the quasi-static failure load and thelogarithm of the tensile speeds Moreover the failure loadsshow similar dynamic sensitivity with respect to the loadingangles
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] N Farabi D L Chen J Li Y Zhou and S J Dong ldquoMicrostruc-ture and mechanical properties of laser welded DP600 steeljointsrdquo Materials Science and Engineering A vol 527 no 4-5pp 1215ndash1222 2010
[2] N Farabi D L Chen and Y Zhou ldquoMicrostructure andmechanical properties of laser welded dissimilar DP600DP980dual-phase steel jointsrdquo Journal of Alloys and Compounds vol509 no 3 pp 982ndash989 2011
[3] S Zhang ldquoFracturemechanics solutions to spot weldsrdquo Interna-tional Journal of Fracture vol 112 no 3 pp 247ndash274 2001
[4] S Zuniga and SD Sheppard ldquoResistance spotweld failure loadsand modes in overload conditionsrdquo in Fatigue and FractureMechanics ASTM STP 1296 pp 469ndash489 American Society forTesting and Materials West Conshohocken Pa USA 1997
[5] M Marya K Wang L G Hector Jr and X Gayden ldquoTensile-shear forces and fracture modes in single and multiple weldspecimens in dual-phase steelsrdquo Transactions of the ASMEJournal of Manufacturing Science and Engineering vol 128 no1 pp 287ndash298 2006
[6] Y J Chao ldquoUltimate strength and failure mechanism ofresistance spot weld subjected to tensile shear or combinedtensileshear loadsrdquo Journal of Engineering Materials and Tech-nology vol 125 no 2 pp 125ndash132 2003
[7] R S Birch and M Alves ldquoDynamic failure of structural jointsystemsrdquo Thin-Walled Structures vol 36 no 2 pp 137ndash1542000
[8] F Schneider and N Jones ldquoInfluence of spot-weld failureon crushing of thin-walled structural sectionsrdquo InternationalJournal of Mechanical Sciences vol 45 no 12 pp 2061ndash20812003
[9] E Bayraktar D Kaplan C Buirette and M Grumbach ldquoAppli-cation of impact tensile testing to welded thin sheetsrdquo Journal ofMaterials Processing Technology vol 145 no 1 pp 27ndash39 2004
[10] X Sun and M A Khaleel ldquoDynamic strength evaluations forself-piercing rivets and resistance spot welds joining similar anddissimilar metalsrdquo International Journal of Impact Engineeringvol 34 no 10 pp 1668ndash1682 2007
[11] M I Khan M L Kuntz and Y Zhou ldquoEffects of weldmicrostructure on static and impact performance of resistancespot welded joints in advanced high strength steelsrdquo Science andTechnology of Welding and Joining vol 13 no 3 pp 294ndash3042008
[12] N Khandoker and M Takla ldquoTensile strength and failuresimulation of simplified spot weld modelsrdquo Materials andDesign vol 54 pp 323ndash330 2014
[13] J H Song and H Huh ldquoFailure characterization of spot weldsunder combined axialshear loading conditionsrdquo InternationalJournal of Mechanical Sciences vol 53 no 7 pp 513ndash525 2011
[14] H Huh S-B Kim J-H Song and J-H Lim ldquoDynamic tensilecharacteristics of TRIP-type and DP-type steel sheets for anauto-bodyrdquo International Journal ofMechanical Sciences vol 50no 5 pp 918ndash931 2008
[15] S-H Lin J Pan T Tyan and P Prasad ldquoA general failurecriterion for spot welds under combined loading conditionsrdquoInternational Journal of Solids and Structures vol 40 no 21 pp5539ndash5564 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Advances in Materials Science and Engineering 9
angle increases at the interval from 45∘ to 90∘ Failurecontours of a spot weld at different tensile speeds were alsoconstructed by decomposing the failure loads measured inthe experiment into two components along the axial andshear directions The constructed failure contours indicatethat failure contour expands as the tensile speed increasesThe results also revealed that dynamic sensitivity can beinterpolated in terms of the quasi-static failure load and thelogarithm of the tensile speeds Moreover the failure loadsshow similar dynamic sensitivity with respect to the loadingangles
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] N Farabi D L Chen J Li Y Zhou and S J Dong ldquoMicrostruc-ture and mechanical properties of laser welded DP600 steeljointsrdquo Materials Science and Engineering A vol 527 no 4-5pp 1215ndash1222 2010
[2] N Farabi D L Chen and Y Zhou ldquoMicrostructure andmechanical properties of laser welded dissimilar DP600DP980dual-phase steel jointsrdquo Journal of Alloys and Compounds vol509 no 3 pp 982ndash989 2011
[3] S Zhang ldquoFracturemechanics solutions to spot weldsrdquo Interna-tional Journal of Fracture vol 112 no 3 pp 247ndash274 2001
[4] S Zuniga and SD Sheppard ldquoResistance spotweld failure loadsand modes in overload conditionsrdquo in Fatigue and FractureMechanics ASTM STP 1296 pp 469ndash489 American Society forTesting and Materials West Conshohocken Pa USA 1997
[5] M Marya K Wang L G Hector Jr and X Gayden ldquoTensile-shear forces and fracture modes in single and multiple weldspecimens in dual-phase steelsrdquo Transactions of the ASMEJournal of Manufacturing Science and Engineering vol 128 no1 pp 287ndash298 2006
[6] Y J Chao ldquoUltimate strength and failure mechanism ofresistance spot weld subjected to tensile shear or combinedtensileshear loadsrdquo Journal of Engineering Materials and Tech-nology vol 125 no 2 pp 125ndash132 2003
[7] R S Birch and M Alves ldquoDynamic failure of structural jointsystemsrdquo Thin-Walled Structures vol 36 no 2 pp 137ndash1542000
[8] F Schneider and N Jones ldquoInfluence of spot-weld failureon crushing of thin-walled structural sectionsrdquo InternationalJournal of Mechanical Sciences vol 45 no 12 pp 2061ndash20812003
[9] E Bayraktar D Kaplan C Buirette and M Grumbach ldquoAppli-cation of impact tensile testing to welded thin sheetsrdquo Journal ofMaterials Processing Technology vol 145 no 1 pp 27ndash39 2004
[10] X Sun and M A Khaleel ldquoDynamic strength evaluations forself-piercing rivets and resistance spot welds joining similar anddissimilar metalsrdquo International Journal of Impact Engineeringvol 34 no 10 pp 1668ndash1682 2007
[11] M I Khan M L Kuntz and Y Zhou ldquoEffects of weldmicrostructure on static and impact performance of resistancespot welded joints in advanced high strength steelsrdquo Science andTechnology of Welding and Joining vol 13 no 3 pp 294ndash3042008
[12] N Khandoker and M Takla ldquoTensile strength and failuresimulation of simplified spot weld modelsrdquo Materials andDesign vol 54 pp 323ndash330 2014
[13] J H Song and H Huh ldquoFailure characterization of spot weldsunder combined axialshear loading conditionsrdquo InternationalJournal of Mechanical Sciences vol 53 no 7 pp 513ndash525 2011
[14] H Huh S-B Kim J-H Song and J-H Lim ldquoDynamic tensilecharacteristics of TRIP-type and DP-type steel sheets for anauto-bodyrdquo International Journal ofMechanical Sciences vol 50no 5 pp 918ndash931 2008
[15] S-H Lin J Pan T Tyan and P Prasad ldquoA general failurecriterion for spot welds under combined loading conditionsrdquoInternational Journal of Solids and Structures vol 40 no 21 pp5539ndash5564 2003
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials