BRI IR 310 ( .

AD-A234 220i LCHNICAL REPORT BRL-TR-3210

BRLFINITE ELEMENT ANALYSES OF

NONPERFORATING BALLISTIC IMPACTSUSING HYDRO-CODE GENERATED

LOADING HISTORIES

ENNIS F. QUIGLEY

FEBRUARY 1991

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED.

U.S. ARMY LABORATORY COMMAND

BALLISTIC RESEARCH LABORATORY

ABERDEEN PROVING GROUND, MARYI AND

91 4~.i

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February 1991 FINAL, JAN 90 - JUN 904. TITLE AND SUBTITLE 5. FUNDING NUMBERSFINITE ELEMENT ANALYSES OF NONPERFORATING BALLISTICIMPACTS USING HYDRO-CODE GENERATED LOADING HISTORIES

6. AUTHOR(S) 1L162618AH80ENNIS F. QUIGLEY

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATIONREPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING /,MONITORING

US ARMY BALLISTIC RESEARCH LABORATORY AGENCY REPORT NUMBER

ATTN: SLCBR-DD-TABERDEEN PROVING GROUND, MD 21005-5066 BRL-TR-3210

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION, AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED

13. ABSTRACT (Maximum 200 words)

By modifying the EPIC-2 hydro-code one can calculate the loading history ofan impacting projectile on a target. Loading histories of 20 mm projectilesfor impact velocities of 366 m/s, 1012 m/s and 1508 m/s on 914 x 914 mm rolledhomogeneous armor plates were calculated with this code. These histories wereused in ADINA finite element analyses of the plates. Comparisons of the measuredand the calculated plate responses show that hydro-code generated loading historiescan be used in finite element analyses of nonperforating ballistic impact.

14 SUBJECT TERMS 15. NUMBER OF PAGESTERMINAL BALLISTICS, IMPACT SHOCK, VULNERAiBILITY, IMPACT LOADING 17HTSTORr-,. LMkui-R SIMULATION, EPIC-2, ADINA 16. PRICE CODE

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT

OF REPORT OF THIS PAGE OF ABSTRACT

UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED SARNSN 7540-01-280-5500 Standard Form 298 (Rev 2-89)

UrFbed b ANSI Sid Z39-UNCLASSIFIED 298102

INTENTIONALLY LEFT BLANKC.

TABLE OF CONTENTS

Page

L IS T O F F IG U R E S .................................................................................................... v

I. INTRODUCTION ................................................... I

I1. EPIC-2 CALCULATED LOADING HISTORIES ....................................................... I

III. A D IN A C A L C U L A T IO N S .... .................................................................................... 3

IV. COMPARISON OF CALCULATED AND MEASURED RES)ONSES ...................... 4

V. SUM\MARY AND CONCLUSIONS ............................................................................ 11

R E F E R E N C E S ........................................................................ ................................ 1 3

D IST R IB U T IO N L IS T ............................................................................................... 15

I-,/

iii

INTENTIONAULY LEF BLANK.

iv

LIST OF FIGURES

Figure Page

1. EPIC-2 calculated impact loading history for v = 366 m//s ............................ 2p

2. EPIC-2 calculated impact loading history for vp = 1012 in/s ........................... 2

3. EPIC-2 calculated impact loading history for v = 1508 m/s ........................... 3p

4. Normal displacement histories at, 10 mm for v = 366 n/s ... . ................ 4P

5. Normal displacement histories at 24, mm for v = 366 rn/s . ................. 5

6. Radial strain histories at 100 m m for v = 366 m /s ........................................ .5P

7. Radial strain histories at 170 mm for v = 366 m/s ........................................ 6p

8. Radial strain histories at 240 mm for v = 366 m/s ....................................... .6P

9. Normal displacement histories at 106 mm for v = 1012 r/s ................. 7P

10. Normal displacement histories at 244 mm for v = 1012m/s ........................... 7p

11. Radial strain histories at 100 m m for v = 1012 m /s ....................................... 8P

12. Radial strain histories at 170 m m for vp = 1012 m is ....................................... 1

p

13. Radial strain histories at 240 mm for Vp = 1012 rn/s .............................. 9

1,1. Normal displacement histories at 24] mm for Vp = 1508 rn/s .....................

15. Radial strain histories at 100 mm for v = 1508 rn/s.............................. 10p

16. R/adial strain histories at 170 mm for vp = 1508 rn/s.............................. 10

17. Radial strain histories at 240 mm for v = 1.508 rn/s .......................... 11

P

INTFNTIONALLY LEFT BLANK.

VI

I. INTRODUCTION

A series of nonperforating ballistic impact experiments i were conducted by the US ArmyCombat Systems Test Activity to characterize the ballistic shock environment in rolledhomogeneous armor targets. Three of these experiments involved the normal impact of a 20 mmfragmunt simulator projectile on 914 x 914 x 38 mm plates at impact velocities of 366 m/s and1012 mis and on a 91-] x 914 x 70 mm plate at an impact velocity of 1508 mis. Normaldisplacements and radial strains were measured at various locations on the back of the plates.The EPIC-2 hydro-code 2 was used by the US Army Ballistic Research Laboratory to model thesethree experiments and to calculate the plate's responses to the impact, of this projectile.Comparison 3 of the measured and tEPIC-2 calcuhited responses of the plates showed that EPIC-2could calculate the response of projectile-im pacted targets.

EPIC-2 is an axisvn mietric code; therefore, it. is limited to axisymmetric targets and tonormal impact of projectiles. If, however, the ElPC-2 code is modified to calculate the projectileloading history of the target, this loading history can be used as input for a finite elementanalysis of ballistic shock in normal impacted, non-axisymmetric targets. The code has beenmodified and loading histories4' 5 have been r'alculated for the previously mentioned 20 mmprojectile impacts. This report describes the application of these loading histories in the ADINA6

finite element anal "-&s of the plates and a comparison of the ADINA calculated responses withthe measured responses.

II. EPIC-2 CALCULATED LOADING HISTORIES

One of the variables calculated by the EPIC-2 code for each computational time intervalis the total linear momentum of the plate. The code is modified to calculate the loading historyof the projectile on the plate by calculating the time rate-of-change in the plate's total linearmomentum over each computational time interval. Although the computational time intervalfor these impact velocities is in the order of 0.05 ps, the loading is printed out at 1.0 s intervals.

Figure 1 shows the computed loading history of the plate for impact velocity of 366 m/s.The duration time of the loading is approximately 40 ps and the maximum peak value of theloading is 800 kN. The shape of the loading pulse shows rectangular characteristics. Figure 2shows the computed loading history for the 1012 m/s impact velocity. The duration time of theloading is 48 pis and the maximum peak value is 3.At MN. This loading history is more oscillatoryin nature than the one shown in Figure 1, and its shape exhibits triangular characteristics.Figure :3 shows the computed loading history of the plate for the impact velocity of 1508 mi/s.The loading has a duration time of 68 p and a maximum peak value of 6.3 MN. For the first 30pLs the loading is very oscillatory with differences of up to 5 MN between maximum andminimum load values. There exists at 46 ILs a negative loading, implying that the projectile ispulling the plate rather pushing against it. A more reasonable explanation can be given in termsof the dilatation wave produced by the iumpacting projectile. The timne at which the negativeloiding occurs is the arrival time of tle wave at the impact point after tle wave's second roundt-ip through tie 70r mim thickness of the plate. Since this is a tension wave when it, arrives, thepl:,te experiences a pulling rather than a pushing Although the lower impact velocity loading

histories show some characteristic shape, this higher 'ilelocitv loaling hit,,r) does not.

O.S-

0. 6 -

Force ( MN) 0.1 -

O. 2 -

0-

0 20 40 60Time (/15)

Figure 1. I1PI(-2 calculated impact loading history for v = 366 m 's.

3-

Force (MN)

0 20 40 60Time (-)

Figure 2. HPlC-2 calculated impact loading history for v = 1012m/s.p

6-

F ('rc (MIN) *

()20 ~ 40 60)Timne (Ois)

Figure :3. FlPl(-2 c( ( llite(I Mira A( loading historY for v p 1508 rn/s.

111. ADINA CALCULATIONS

I'lie Al)!NA fil tee iien t inodelIs of t ie plates are identical to the models used in theEIC(-2 ca lea at ions of t he )1tesresponses 2and the loading hiistories4 -5 . The squ are p~lates arenwl((lled a-s a circular ones WithI radii of .157 mm andl having free boundaries. The analyses areaxisvYni metrnc. The 38 in thick plate mnode! consistrs of 671 nodes and 1200 triangular elements.B(t ih the horizontal and the vertical distances between the nodes are 7.62 mim. The 70 mm thickpli t e rniodel consists of 1 020 nlodes and 1760 triangular elements. Thle horizontal and the verticald i-i ances bet ween thle n~lsare 7.62 11T iand] S.67 tutu. re'spect ively. One thiird of the loading is:tplid to each of thle top) first t hree radlial nodes. (Recovery' of the 20 mm projectiles after theexp('rinlents showed that thle contact surface of thle projectile mushroomed from a 20 mm(lianeter to a 33 rum diameter.) The analyses are nonlinear material only, small deflection andsmall strain. The time Integrat ion scheme used is the Newmark method with a time stepncernent of I its. The fullI Newton equilibrium Iteration method without line search is used forhew 38 mmn thick pae.and( the full Newton equilibrium iteration method with line search is

used( for the 70 min thick plate

The material mnodel of the plates is bilinear elastic-plastic in which Young's modulus EI 15. 1 CWa, Poisson's raitio, v = 0,275, yield st ressui= 916.2 NIPa, and strain hardening modulus

E.T =510. %Wla: and the density of thle plate Is 78S76 kg nI13 The sam ni material properties were

1isedl ini the IPIC-2 caleulitV is of thle loadingfitri.

IV. COMPARISON OF CALCULATED AND MEASURED RESPONSES

i gires -1 through 17 show thc eahrllrted arnd iiieastred plate rc.s)orise histories at thle100) rml 106 rin, 170 mill 2.10 rum md 2.11 itum trausducer locatiows for thle first 300) ps. Fortrfw> greater thi:lt 2-50 jis, the plate's geoniet rv and( boundary conditions do affect the plate's

is.:111d1 any cornaais7;11or of dat a is riot invaringful. Zero I inres, ol the tniea-suredl responses,rirfdisplacenrents mi' r:idhial strains. (1o riot coincide with the time -' impact aIr~ therefore

d-nct cor respondt to the zero timec of li h calculated respo'.sies. Zero t imnes of the m easured* f-j-t's :ire :rdjrrst d Mi o rder to corripare the( (l1t:', arid these adjusted t1res are thre 53 iii ones

tii> m iic hcorriiI.tvm () thre VKI( -2 c:ilciilted esponis-s wvit tire niceirsrrred responses.

icIre hirrigh thh~w le responses of the 3S inn)r thick plite for the impact velocitvi I'iur is 9 ti r' 'uh 1 3 show thIe responses of' a sun ilmr phit e for thre 1012 tin s iii pactI.

ii v. 1icnires I I through 17 aire For the 70 trim thick phlte f'or the( irpact velocli of 1508III- It cmr he In en 1 row t hiese figu res timht the :ig-eieret bet \\et thle mirsiired plate responses

:1, k, e-:1 lellit eu reslics ranges I'rotr goodi to excellet

IN5) -1

50 AIIN

0100 200 300)ime (/I-,)

[I gurr 1. Normail (hisllaceuient listesW it 16 t11t1 fot v .366i in "S.

50 -... .

Displacement

0 . - MEASURED

0 100 2u0 300Time (its)

Figure 5. Normal displacement histories at 244 mm for v p 366 rn/s.

0

Strain(gistrain)

-.500-

-MEASURED

1000 - ....ADINA

0 100 200 300Time (ps)

F'iguire 6. Radial strain histories at 100 mm for v p= 366 in/s.

5

5)00-

Strain0(hlstrain)

-~.... :)0) Jfl'TN '

()100 200 300Time (ps)

Figure 7. Radial strain histories at 170 mm for v p 366 rn/s

Strain(Ilstrain)

-509- MASURED)

0 100 200 300Time (his)

Figure S. Radial strain histories at 240 mm for v p 366 rn/s.

6

500 -..

4100 -...

300()

Displacement(,um)

200)

1 00 -

M EASURED

0* AI)INA

0100 200 300Time (ps)

Figure 9. Normal displacement histories at 106 mm for v p 1012 m/s.

200

100-

Displacement(Pm)

..................................... MA URNA

0 100 200 300Time (ps)

Figure 10. Normal displacement histories at 244 mm for v p 1012 in/s.

7

0

Strain

-MEASURED

-2000 ..... AIINA

0100 200 300Time (;is)

Figure 11. Radial strain histories at 100 mm for v p 1012 rn/s.

1000-

0-

Strain(distrain) *

- I00()

MIEASU RED

0 100 200 300

Time (pzs)

Figure 12. Radial strain histories at 170 mm for v - 1012 rn/s.

50()

0-

Strain(listrain)

-50()

-100 . .____MEASURED

.. -AIINA

0 100 200 300Time (its)

Figure 13. Radial strain histories at 240 mm for v = 1012 rn/s.

150-

100-

Displacement(AiM)

50-

MEASURED

0 .ADINA

0 100 200 300

Time (s

Figure I A. Normal displacement histories at 244 mm for v P= 1 508 rn/s.

9

500-

0-

Strain(Ipstrain) -0

-00

MELASURED

A DIINA-1500-______________________________

0 100 200 300Time (its)

Figure 15. Radial strain histories at 100 mm for v p 1508 rn/s.

300-

0Strain

(ptstrain)Z

MEASURED

-1000 ADINA

0 100 200 300Time (i;

Figure 16. Radial strain histories at 170mrm for vp 1508 rn/s.

10

&00 -

0-Strain

(pstrain)

-500-

- MEASURED

........ ADINA

0 100 200 300

Time (pis)

Figure 17. Radial strain histories at 240 mm for v = 1508 m/s.

V. SUMMARY AND CONCLUSIONS

EPIC-2 hydro-code calculated loading histories of rolled homogeneous armor plates fromimpacting 20 mm projectiles have been used in finite element analyses of the plates' responses tothese impacts. The projectile impacts were normal to the plate surface and nonperforating.During the computation of the loading histories, the projectile material was allowed to fail anderode whereas the plate material was not. Comparison of the measured and the finite elementcalculated responses of the plates show that these calculated loading histories when used in finiteelement analyses of the plates' responses give good to excellent results for this particular type ofimpact.

Non-normal impact, kinetic energy rod impact and shaped charge warhead impact are ofgreater importance. The latter is of special interest in that it involves both high explosive blastloading and shaped charge jet loading. Whether or not hydro-codes can provide loading historiesfor these types of impact for use in finite element analyses of ballistic impact is a question still tobe answered.

11

INTIMONALLY LEFT BLANK.

12

REFERENCES

1. Gordon R. Johnson, "EPIC-2: A Computer Program for Elastic-Plastic ImpactComputations in 2 Dimensions Plus Spin," ARBRL-00373, June 1978

2. Ennis F. Quigley, "EPIC-2 Predicted Shock Environments in Rolled Homogeneous Armorfor Nonperforating Ballistic Impact," BRL-TR-2886, January 1988

3. W. Scott Walton, "Characterization of Ballistic Shock," USACSTA-6262, November 1985

,t. Ennis F. Quigley, "EPIC-2 Calculated Impact Loading Histories of Thin Plates,"BRL-TR-3011, June 1989

5. Ennis F. Quigley, "EtPIC-2 Calculated Impact Loading History for Finite ElementAnalysis of Ballistic Shock," BRL-TR-3058, December 1989

6. ADINA R&D, Inc., "ADINA Users Manual," Volumes 1 and 2, ARD 87-1, December 1987

13

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