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OPTIMAT BLADES

Summary Fatigue Test Report

OB_TG1_R026 rev. 0

Confidential

TG 1

Olaf Krause Christoph Kensche

OB_TG1_R026 rev.0 OPTIMAT BLADES of 38 Last saved 15.04.2006 20:57 Change record

Issue/revision date Pages Summary of changes

0 01.04.06 All New document

OB_TG1_R026 rev.0 OPTIMAT BLADES of 38 Last saved 15.04.2006 20:57 Table of contents 1 Introduction.........................................................................................................4 2 Materials ..............................................................................................................4 3 Laminates ............................................................................................................4 4 Specimens...........................................................................................................5 5 Test program.......................................................................................................6

5.1 Test program........................................................................................................... 6 5.2 Testing conditions.................................................................................................... 6 5.3 Testing procedures.................................................................................................. 6

6 Results achieved in Phase 1..............................................................................7 6.1 Constant amplitude testing ...................................................................................... 7

6.1.1 UD2, R=-1 ........................................................................................................ 7 6.1.2 MD2, R=-1........................................................................................................ 8 6.1.3 MD2, R=0.1...................................................................................................... 9 6.1.4 MD2, R=0.5.................................................................................................... 10 6.1.5 MD2, R=-0.4................................................................................................... 11 6.1.6 MD2, R=-2.5................................................................................................... 12 6.1.7 MD2, R=10..................................................................................................... 13 6.1.8 MD2, R=2....................................................................................................... 14

6.2 Variable amplitude testing ..................................................................................... 14 6.2.1 Simple block tests .......................................................................................... 14 6.2.2 Repeated block tests...................................................................................... 17 6.2.3 Load spectra tests .......................................................................................... 19

7 Results achieved in Phase 2............................................................................19 7.1 Constant amplitude testing .................................................................................... 19

7.1.1 MD4, R=0.1.................................................................................................... 19 7.2 Variable amplitude testing ..................................................................................... 20

8 Comparison of results......................................................................................21 8.1 Constant amplitude testing .................................................................................... 21 8.2 Variable amplitude testing ..................................................................................... 28

8.2.1 Simple block tests .......................................................................................... 28 8.2.2 Repeated block tests...................................................................................... 33 8.2.3 Load spectra tests .......................................................................................... 37

9 Summary and Conclusions..............................................................................37 10 References .....................................................................................................38

OB_TG1_R026 rev.0 OPTIMAT BLADES of 38 Last saved 15.04.2006 20:57

1 Introduction This report describes the extensive fatigue testing campaign accomplished at DLR laboratory within Task Group 1 of the ‘OPTIMAT BLADES’ project and illustrate its basic results. Fa-tigue testing had to be performed during the Phase 1 and Phase 2 of the 52-month project. Testing in Phase I concentrated on detailed material characterization of a reference material by establishment of several S-N curves using constant amplitude testing and the formulation of a detailed Constant Life Diagram (CLD). For better understanding and improvement of lifetime prediction methodologies the influence of alternating load sequences and load spec-tra were investigated by variable amplitude testing. The shorter Phase 2 concentrated on constant amplitude testing of an alternative material to investigate the effects on lifetime prediction.

2 Materials Two reference materials of glass fiber reinforcement were supplied by LM Glasfiber A/S for the project. The first one is a single-layer unidirectional material of non-woven glass rovings from PPG with a minor amount of off-axis reinforcement. The second one is a biaxial material made of non-woven glass rovings from PPG as well. The build-up consists of two layers ar-ranged in +45° and -45° direction and stitched together with a polyester yarn. These reference materials were used in Phase 1 and Phase 2 of the project. For infusion of the reference material, in Phase 1 the epoxy resin Prime 20 with slow hardener from SP Sys-tems was used and in Phase 2 the resin LM-E6. The laminates used in Phase 1 are men-tioned as reference material, these in Phase 2 as alternative material. Detailed information about the materials is given in [1].

3 Laminates Two standard laminates, a unidirectional laminate (UD) and a multidirectional laminate (MD) are basis of the experimental work in all Task Groups of the whole project. The lay-up of the UD laminate consists of 4 layers of the UD reference material with laminae thickness of 0.88 mm yielding to a total nominal thickness of 3.52 mm. The lay-up of the MD laminate consists of 5 layers of the biaxial reference material (±45º) inter-spaced with four layers UD. Thickness of the ±45 -layers is 0.61 mm and for the UD 0.88 mm as before. Total nominal thickness of the MD laminate is 6.57 mm. Laminates are fabricated by infusion of the dry laminate package with epoxy resin by vacuum assisted resin transfer moulding. After initial curing at room temperature laminates are post-cured at 80°C for 4 hours. In Phase 1 and Phase 2 the same lay-up was used for the laminates. The multidirectional laminate used in Phase 1 is named MD2, these of Phase 2 MD4.


4 Specimens Two geometries are used in general for the standard Optimat specimen made of the two laminates. The geometries for the standard UD specimen and the standard MD specimen are shown in Figure 1 and Figure 2 respectively. The UD specimen is used for 0° and 90° lay-up as well.

Figure 1: Optimat Blade specimen (UD)

Figure 2: Optimat Blade specimen (MD)

The only difference between the two OPTIMAT standard specimens is the increased gauge length for the MD material and the higher thickness of the laminate. All experimental work described in this report was accomplished with the OPTIMAT standard specimens.

2h

145

55 5535

25

2h

150

55 5540

25


5 Test program

5.1 Test program The test types used within the experimental work are given in this section. An overview of the selected types of tests is given in Table 1. In the description for each of these tests the test method, used laminate, and specific testing conditions are given. Fatigue testing at DLR concentrated on the MD material. A detailed overview and explanation of the tests is given in the detailed plans of action (DPA) for the two phases of the project ([2],[3]).

Types of tests # Test method Laminate Geometry

(OB Definition) Testing

condition 1 Fatigue, T-T (R=0.1) MD2, MD4 R400 RT, Dry 2 Fatigue, T-T (R=0.1) UD2 R300 RT, Dry 3 Fatigue, T-T (R=0.5) MD2 R400 RT, Dry 4 Fatigue, T-C (R=-0.4) MD2 R400 RT, Dry 5 Fatigue, T-C (R=-1.0) MD2 R400 RT, Dry 6 Fatigue, T-C (R=-1.0) UD2 R300 RT, Dry 7 Fatigue, T-C (R=-2.5) MD2 R400 RT, Dry 8 Fatigue, C-C (R=2.0) MD2 R400 RT, Dry 9 Fatigue, C-C (R=10.0) MD2 R400 RT, Dry

10 Fatigue, load spectra MD2 R400 RT, Dry 11 Fatigue, block test MD2 R400 RT, Dry

Table 1: Overview of test types

All test results were reported in the official database, OptiDat.

5.2 Testing conditions All tests were accomplished under ambient conditions in a non-air-conditioned lab.

5.3 Testing procedures Since several laboratories were involved in the experimental work of the project, the tests had to be accomplished as comparable as possible. Therefore a set of testing specifications ([4], [5]) was established to avoid different test results due to a deviating accomplishment of the tests.


6 Results achieved in Phase 1

6.1 Constant amplitude testing Constant amplitude testing within Phase 1 took much more time than expected. The reason for that was the delayed start of the testing programme because some preliminary test pro-grammes were necessary to fix the geometry of the specimen. Additionally much lower test-ing frequencies than foreseen could be used, because significant heating could be observed during the first tests. For these reasons the testing programme could not be completely ful-filled. 79 valid results of 85 tested specimens could be reported with in total 94.655.717 load cycles requiring 4950 hours of testing time. The results of the constant amplitude tests are given in the following paragraphs. The de-tailed test results including the most important information are listed in the relevant tables. In cases where no strain measurement was available, strain was calculated by the average modulus obtained with the data of all static tests available in OptiDat. In these cases the value is marked with ‘*)’ and the values of the relevant average modulus given, 26.89 GPa for tensile modulus and 27.80 GPa for compressive modulus. The data points and S-N curves are shown in the corresponding figures. S-N curves were derived using two methods, linear regression and the method of Sendeckyj, which is based on a two-parametric Weibull distribution. Generally the statistical evaluation showed no significant differences comparing these methods. The fatigue slopes are usually almost the same. Differences can be seen, if only a small number of results was available and for load cycle numbers below 5.000 to 10.000. But there is no pure fatigue present at these high loads, so the difference in these loading regimes is of less importance.

6.1.1 UD2, R=-1 The UD material was tested as a benchmark to compare the results obtained at these labs which are focusing on testing of the UD material. 10 specimens were tested at R=-1 using the same stress levels and testing frequencies which were used at the University of Patras (UP) for establishment of the S-N curve.

Load Stress Strain E_tens E_compr f Coupon-ID R-Ratio [kN] [MPa] [%]

Cycles [GPa] [GPa] [Hz]

GEV206-R0300-0117 -1 28.03 300.0 0.81 6753 37.72 37.82 1.52 GEV206-R0300-0118 -1 24.81 260.0 0.71 25565 37.28 37.27 2.00 GEV206-R0300-0120 -1 24.86 260.0 0.70 40605 38.03 38.07 2.00 GEV206-R0300-0123 -1 24.64 260.0 0.71 30712 37.23 37.32 2.00 GEV206-R0300-0119 -1 20.49 210.3 0.59 135051 36.34 36.38 3.13 GEV206-R0300-0122 -1 20.14 210.0 0.57 167968 37.46 37.51 3.13 GEV206-R0300-0121 -1 19.80 210.0 0.57 214983 37.56 37.67 3.13 GEV206-R0300-0115 -1 16.68 180.0 0.49 675361 37.77 38.23 4.32 GEV206-R0300-0116 -1 16.77 180.0 0.50 658702 37.44 37.01 4.32 GEV206-R0300-0114 -1 17.01 180.0 0.48 682835 38.15 38.05 4.32

Table 2: Overview of test results UD R=-1


S-N-Curve UD-DataR=-1

0

100

200

300

400

500

600

700

800

900

1000

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]

Test Results

Mean ValueSendeckyj

Mean Value Linear regression

Figure 3: UD2 R=-1

6.1.2 MD2, R=-1 At R=-1 in total 18 specimens of the MD material were tested with 15 valid results. The re-sults showed very low scatter. The testing frequencies had to be chosen very low to avoid overheating of the specimens. Nevertheless, temperatures up to 40°C could be measured on the surface of the specimen. Some specimens showed a slightly buckling behavior. In almost any case failure occurred due to tensile loading of the specimen.

Load Stress Strain E_tens E_compr f Coupon-ID R-Ratio

[kN] [MPa] [%] Cycles

[GPa] [GPa] [Hz] GEV207_R0400_0708 -1 17.32 103.77 0.39 *) 596635 26.89- 27.80 4.39

GEV207_R0400_0129 -1 31.20 184.98 0.72 48942 26.78 26.18 1.37

GEV207_R0400_0124 -1 42.81 250.01 1.02 1534 26.03 24.99 0.75

GEV207_R0400_0120 -1 31.32 185.03 0.70 59468 27.37 26.77 1.37

GEV207_R0400_0118 -1 33.47 200.00 0.78 16291 27.02 26.37 1.17

GEV207_R0400_0117 -1 42.32 250.01 1.01 2608 26.00 25.09 0.75

GEV207_R0400_0116 -1 31.44 184.98 0.75 57038 25.80 25.02 1.37

GEV207_R0400_0115 -1 21.00 124.39 0.48 2098460 26.82 26.46 3.00

GEV207_R0400_0114 -1 28.98 175.00 0.66 109901 27.67 26.98 1.53

GEV207_R0400_0113 -1 22.42 134.99 0.52 735186 26.90 26.46 2.57

GEV207_R0400_0112 -1 22.25 134.99 0.49 655532 28.28 27.90 2.57

GEV207_R0400_0111 -1 25.22 150.00 0.57 481189 27.32 26.83 2.08 GEV207_R0400_0110 -1 41.59 250.03 1.01 2074 25.97 25.13 0.75

GEV207_R0400_0109 -1 37.54 224.98 0.90 8234 26.36 25.48 0.93

GEV207_R0400_0108 -1 22.70 134.98 0.52 637851 26.60 26.15 2.57

Table 3: Overview of test results MD2 R=-1


S-N-Curve MD-DataR=-1

0

100

200

300

400

500

600

700

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]

Test Results

Mean ValueSendeckyj


Figure 4: MD2 R=-1

6.1.3 MD2, R=0.1 At R=0.1 in total 16 specimens of the MD material were tested with 15 valid results. The re-sults showed very low scatter. For all specimens failure was initiated by the debonding of the tabs and fracture occurred in or nearby the load introduction. This is an obvious evidence that the design of the specimen is not able to avoid significant stress concentration.

Load Stress Strain E_tens f Coupon-ID R-Ratio


[GPa] [Hz] GEV207_R0400_0541 0.1 55.97 343.06 1.28 *) 3058 26.89 2.11

GEV207_R0400_0123 0.1 27.22 159.99 0.63 5167411 28.80 9.04

GEV207_R0400_0294 0.1 32.84 194.98 0.75 1023212 27.50 6.10

GEV207_R0400_0130 0.1 32.74 195.00 0.75 1550777 28.07 6.10

GEV207_R0400_0119 0.1 32.85 195.27 0.75 1529500 27.87 6.10

GEV207_R0400_0126 0.1 42.48 249.98 1.00 72213 27.20 3.70

GEV207_R0400_0296 0.1 43.86 259.97 1.02 42577 27.24 3.42

GEV207_R0400_0121 0.1 43.80 259.99 1.04 57647 27.06 3.42

GEV207_R0400_0133 0.1 43.91 260.02 1.03 71242 27.49 3.42

GEV207_R0400_0127 0.1 50.72 299.99 1.20 13591 27.19 2.57

GEV207_R0400_0125 0.1 62.76 375.02 1.52 1548 27.43 1.65

GEV207_R0400_0132 0.1 66.56 389.99 1.62 1177 27.36 1.52

GEV207_R0400_0293 0.1 65.86 390.00 1.55 1028 28.49 1.52

GEV207_R0400_0295 0.1 65.52 390.02 1.56 995 27.32 1.52

GEV207_R0400_0128 0.1 68.29 400.00 1.64 771 27.21 1.45

Table 4: Overview of test results MD2 R=0.1


S-N-Curve MD-DataR=0.1

0

100

200

300

400

500

600

700

800

900

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]

Test Results

Mean ValueSendeckyj


Figure 5: MD2 R=0.1

6.1.4 MD2, R=0.5 At R=0.5 in total 8 specimens of the MD material were tested with 8 valid results. The results showed noticeable scatter. This could possibly explained by the fact, that the specimens were cut from different plates. The specimens of one of these plates (87) showed also poor behavior in other tests. Failure was randomly distributed in the tab area and the gauge area.



[GPa] [Hz] GEV207_R0400_0741 0.1 35.10 213.58 0.79 13287026 26.89 7.50

GEV207_R0400_0539 0.1 45.05 276.58 1.03 72890 26.89 3.35

GEV207_R0400_0538 0.1 44.87 274.42 1.02 82582 26.89 3.35

GEV207_R0400_0740 0.1 44.25 272.31 1.01 852309 26.89 3.35

GEV207_R0400_0537 0.1 57.82 355.02 1.32 10840 26.89 2.10

GEV207_R0400_0534 0.1 57.82 355.02 1.32 8738 26.89 2.10

GEV207_R0400_0739 0.1 57.48 352.31 1.31 47983 26.89 2.10

GEV207_R0400_0535 0.1 44.60 274.39 1.02 79300 26.89 3.35

Table 5: Overview of test results MD R=0.5



0

100

200

300

400

500

600

700

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]

Test Results

Mean ValueSendeckyj


Figure 6: MD2 R=0.5

6.1.5 MD2, R=-0.4 At R=-0.4 in total 12 specimens of the MD material were tested with 12 valid results. The results showed noticeable scatter. This could possibly explained by the fact, that the speci-mens were cut from different plates. Fracture occurred in all cases in the part of the load cy-cle in which tensile loading is applied to the specimen.



[GPa] [GPa] [Hz] GEV207_R0400_0709 -0.4 15.81 95.44 0.36 *) 39393907 26.89 27.80 7.90

GEV207_R0400_0281 -0.4 35.82 210.00 0.79 62379 27.60 27.80 1.80

GEV207_R0400_0457 -0.4 35.97 213.86 0.79 103657 27.07 27.97 1.80

GEV207_R0400_0458 -0.4 40.10 239.82 0.90 36849 26.75 26.46 1.45

GEV207_R0400_0459 -0.4 47.25 279.91 1.05 14519 26.68 26.42 1.03

GEV207_R0400_0460 -0.4 54.93 330.27 1.26 2265 26.20 25.75 0.76

GEV207_R0400_0461 -0.4 25.22 150.38 0.56 2308278 26.83 26.98 3.63

GEV207_R0400_0547 -0.4 27.30 168.21 0.58 116481 29.03 29.23 3.11

GEV207_R0400_0548 -0.4 29.77 183.51 0.64 69767 28.76 28.78 2.61

GEV207_R0400_0561 -0.4 25.81 159.66 0.75 10863 29.51 27.80 1.80

GEV207_R0400_0562 -0.4 35.58 225.00 0.78 13070 28.82 28.83 1.80

GEV207_R0400_0566 -0.4 40.00 249.98 0.88 7567 28.33 28.23 1.45

Table 6: Overview of test results MD2 R=-0.4


S-N-Curve MD-DataR=-0.4

0

100

200

300

400

500

600

700

800

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]

Test Results

Mean ValueSendeckyj


Figure 7: MD2 R=-0.4

6.1.6 MD2, R=-2.5 At R=-2.5 only 4 specimens of the MD material were tested with 4 valid results. Due to the small number of tests no conclusions can be drawn. Fracture occurred in all cases in the part of the load cycle in which tensile loading is applied to the specimen and was located in the tab area. Since no sound statistical evaluation is possible with this limited number of results, the curves can only be taken as a trend.



[GPa] [GPa] [Hz] GEV207_R0400_0530 -2.5 48.80 299.98 1.12 *) 3050 26.89 27.80 1.06

GEV207_R0400_0726 -2.5 41.13 249.95 0.93 *) 93144 26.89 27.80 1.53

GEV207_R0400_0529 -2.5 44.32 275.00 1.02 *) 2755 26.89 27.80 1.26

GEV207_R0400_0533 -2.5 24.44 150.36 0.56 *) 3322798 26.89 27.80 4.25

Table 7: Overview of test results MD2 R=-2.5



0

100

200

300

400

500

600

700

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]

Test Results

Mean ValueSendeckyj


Figure 8: MD2 R=-2.5

6.1.7 MD2, R=10 At R=10 in total 17 specimens of the MD material were tested with 15 valid results. The scat-ter of the results is low. Some specimens showed buckling behavior, but severity of buckling was minor in comparison to these specimens which showed buckling at R=-1.

Load Stress Strain E_compr f Coupon-ID R-Ratio


[GPa] [Hz] GEV207_R0400_0313 10 41.72 249.98 0.94 10173865 28.02 3.70

GEV207_R0400_0314 10 58.63 350.00 1.34 917 28.47 1.89

GEV207_R0400_0306 10 50.17 299.97 1.12 4206 28.85 2.57

GEV207_R0400_0307 10 49.94 299.99 1.12 16743 28.22 2.57

GEV207_R0400_0310 10 46.39 274.99 1.03 231071 28.58 3.06

GEV207_R0400_0308 10 53.95 325.00 1.21 2303 28.32 2.19

GEV207_R0400_0311 10 44.48 264.98 0.99 4744812 28.54 3.20

GEV207_R0400_0312 10 56.34 337.14 1.30 1540 27.99 2.08

GEV207_R0400_0301 10 49.37 294.09 1.11 20876 28.16 2.40

GEV207_R0400_0302 10 44.66 269.01 1.01 735964 28.42 3.04

GEV207_R0400_0304 10 56.09 339.45 1.27 1986 28.75 1.95

GEV207_R0400_0303 10 49.33 293.64 1.09 53888 28.71 2.54

GEV207_R0400_0300 10 48.89 297.73 1.15 27302 27.65 2.54

GEV207_R0400_0565 10 44.32 277.86 0.95 876261 31.13 3.04

GEV207_R0400_0298 10 44.87 271.48 0.99 74741 28.69 3.04

Table 8: Overview of test results MD2 R=10


S-N-Curve MD-DataR=10

0

50

100

150

200

250

300

350

400

450

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]

Test Results

Mean ValueSendeckyj


Figure 9: MD2 R=10

6.1.8 MD2, R=2 No specimens were tested at R=2 due to the lack of time.

6.2 Variable amplitude testing Variable amplitude testing consisted of 3 types of testing. The first two test types are block tests, which represented a very simplified load sequence. The third type is a real load spec-tra test. The philosophy of block testing is explained in detail in [2].

6.2.1 Simple block tests In the simple block tests, the specimens were tested at a certain loading condition up to 50% of their nominal fatigue life representing the first block. In the second block the loading condi-tion changed and the specimens were tested until fracture. 60 simple block tests were accomplished with in total 8.673.750 load cycles requiring 682 hours of testing time. 57 of these tests could be declared a valid test. Detailed information is given in the following table. In cases where no strain measurement was available, strain was calculated by the averaged modulus extracted from OptiDat. In these cases the value is marked with ‘*)’ and the values of the relevant average modulus given, 26.89 GPa for tensile modulus and 27.80 GPa for compressive modulus. The initial strain at the beginning of the second block was calculated using the modulus determined at the beginning of the test (if applicable) or the corresponding averaged modulus of OptiDat. During 15 tests the specimen failed in the first block, that means before reaching 50% of the nominal lifetime. This occurred especially in these tests using R=-1 in the first block.


Block 1 Block 2

Load Stress Strain f Load Stress Strain f Coupon-ID Level R

[kN] [MPa] [%] [Hz] Cycles Level R

[kN] [MPa] [%] [Hz] Cycles

Total Cycles

E_tens [GPa]

E_compr [GPa]

GEV207_R0400_0282 1 -1 46.28 278.96 1.06 0.63 443 – 443 26.75 25.73

GEV207_R0400_0283 1 -1 46.37 280.23 1.04 0.63 349 – 349 27.59 26.35

GEV207_R0400_0285 2 -1 30.62 184.70 0.68 1.44 25000 1 -1 46.31 279.35 1.03 0.63 236 25236 27.61 26.88

GEV207_R0400_0286 2 -1 30.53 183.90 0.71 1.44 25000 1 -1 46.17 278.11 1.03 0.63 217 25217 27.93 25.85

GEV207_R0400_0287 2 -1 30.44 182.76 0.68 1.44 25000 1 -1 46.04 276.42 1.01 0.63 354 25354 27.87 27.03

GEV207_R0400_0288 1b -1 39.47 234.09 0.87 *) 0.84 2500 2 -1 30.52 181.01 0.67 *) 1.44 65975 68475 26.89 27.80

GEV207_R0400_0289 1b -1 38.94 236.30 0.88 *) 0.84 2500 2 -1 30.40 184.48 0.69 *) 1.44 54168 56668 26.89 27.80

GEV207_R0400_0290 2 10 49.20 299.55 1.03 2.55 25000 2 0.1 44.65 271.85 0.93 3.34 38340 63340 26.89 29.11

GEV207_R0400_0291 2 10 49.24 296.82 1.06 2.55 25000 2 0.1 44.69 269.39 0.96 3.34 26347 51347 26.89 28.05

GEV207_R0400_0292 2 0.1 44.76 268.57 0.96 3.34 25000 2 10 49.32 295.93 1.05 2.55 456019 481019 28.08 27.80

GEV207_R0400_0317 2 -1 30.52 183.68 0.70 1.44 5896 – 5896 26.88 26.05

GEV207_R0400_0318 1b 10 53.49 320.19 1.15 2.18 2500 3 10 44.62 267.10 0.96 3.15 42621 45121 26.89 27.90

GEV207_R0400_0319 2 -1 30.64 183.35 0.64 1.44 25000 1b 0.1 56.46 337.86 1.19 2.11 1732 26732 27.81 29.17

GEV207_R0400_0320 1b 10 53.53 318.73 1.17 2.18 2500 3 10 44.65 265.85 0.98 3.15 66419 68919 26.89 27.19

GEV207_R0400_0432 1b 0.1 55.88 339.40 1.28 2.11 2500 2 -1 30.32 184.15 0.70 1.44 10814 13314 26.43 27.80

GEV207_R0400_0433 2 0.1 44.65 264.86 1.00 3.34 25000 1b 0.1 56.26 333.73 1.26 2.11 2939 27939 26.39 27.80

GEV207_R0400_0434 2 0.1 44.73 259.72 0.98 3.34 25000 1b 0.1 56.40 327.48 1.23 2.11 2166 27166 26.59 27.80

GEV207_R0400_0435 2 -1 30.52 184.12 0.68 *) 1.44 25000 1b 0.1 56.26 339.40 0.68 2.11 852 25852 27.83 27.23

GEV207_R0400_0436 1b 10 53.00 309.96 1.18 2.18 2500 2 -1 30.51 178.43 0.68 1.44 75765 78265 26.89 26.41

GEV207_R0400_0437 1b 10 53.28 312.14 1.17 2.18 2500 2 -1 30.55 178.98 0.67 1.44 92914 95414 26.89 26.58

GEV207_R0400_0438 1b 10 53.05 323.65 1.28 2.18 2500 2 -1 30.42 185.59 0.73 1.44 33128 35628 26.89 25.30

GEV207_R0400_0439 1b 0.1 55.97 343.59 1.28 *) 2.11 2378 – 2378 26.89 27.80

GEV207_R0400_0440 2 10 49.26 289.77 1.11 2.55 25000 1b 10 53.30 313.53 1.20 2.18 8990 33990 26.89 26.16

GEV207_R0400_0441 3 0.1 33.01 203.09 0.76 *) 6.1 500000 1b 0.1 56.20 345.76 1.29 *) 2.11 1225 501225 26.89 27.80


Block 1 Block 2




Total Cycles

E_tens [GPa]

E_compr [GPa]

GEV207_R0400_0442 2 -1 30.56 179.50 0.67 *) 1.44 25000 1b 10 53.38 313.53 1.13 *) 2.18 3545 28545 26.89 27.80

GEV207_R0400_0443 1b -1 39.09 231.34 0.88 0.86 943 – 943 27.24 26.75

GEV207_R0400_0444 2 10 49.22 288.90 1.05 2.55 9922 – 9922 26.89 27.47

GEV207_R0400_0445 2 0.1 44.52 266.19 1.05 3.34 25000 1b 0.1 56.08 335.31 1.32 2.11 631 25631 25.45 27.80

GEV207_R0400_0446 2 10 48.90 290.26 1.11 2.55 25000 1b 10 52.90 314.00 1.20 2.18 1439 26439 26.89 26.20

GEV207_R0400_0447 1b 10 52.97 313.57 1.31 2.18 2383 – 2383 26.89 23.96

GEV207_R0400_0448 2 10 49.14 287.61 1.07 2.55 8694 – 8694 26.89 26.90

GEV207_R0400_0449 1b 0.1 56.44 333.33 1.30 2.11 2500 1b 10 53.40 315.37 1.23 2.18 1594 4094 25.55 27.80

GEV207_R0400_0450 1b 0.1 56.33 329.40 1.30 2.11 2500 2 0.1 44.71 261.45 1.03 3.34 52694 55194 25.36 27.80

GEV207_R0400_0451 1b 10 53.15 310.75 1.16 2.18 2500 2 10 49.12 287.18 1.07 2.55 8561 11061 26.89 26.83

GEV207_R0400_0452 1b 10 53.28 314.47 1.12 2.18 2500 3 10 44.44 262.30 0.94 3.15 1612701 1615201 26.89 28.01

GEV207_R0400_0453 1b 0.1 56.13 331.59 1.21 2.11 2500 1b 10 53.11 313.75 1.15 2.18 392 2892 27.31 27.80

GEV207_R0400_0454 1b 0.1 55.72 331.31 1.28 2.11 2500 2 0.1 44.23 262.99 1.02 3.34 61662 64162 25.87 27.80

GEV207_R0400_0455 1b 0.1 56.22 330.87 1.29 2.11 2500 2 0.1 44.62 262.60 1.03 3.34 9919 12419 25.56 27.80

GEV207_R0400_0456 2 0.1 44.57 266.17 0.95 3.34 25000 2 10 49.10 293.23 1.04 2.55 146217 171217 28.16 27.80

GEV207_R0400_0462 1b -1 39.12 233.42 0.91 0.84 811 – 811 26.32 25.52

GEV207_R0400_0463 1b 10 53.07 316.84 1.11 2.18 2500 1b 0.1 56.08 334.81 1.18 2.11 6483 8983 26.89 27.29

GEV207_R0400_0464 1b 10 53.30 314.93 1.18 2.18 2500 2 10 49.26 291.06 1.09 2.55 34844 37344 26.89 26.80

GEV207_R0400_0465 3 10 44.56 263.45 0.98 3.15 500000 1b 10 53.43 315.90 1.17 2.18 15913 515913 26.89 27.02

GEV207_R0400_0466 1b 10 53.59 316.79 1.18 2.18 2500 1b 0.1 56.64 334.82 1.24 2.11 4863 7363 26.89 26.92

GEV207_R0400_0467 1b -1 39.12 233.42 0.92 0.84 805 – 805 25.80 25.37

GEV207_R0400_0468 2 -1 30.61 181.39 0.67 *) 1.44 25000 1b 10 53.38 316.32 1.14 *) 2.18 1928 26928 26.89 27.80

GEV207_R0400_0469 1 10 53.00 313.04 1.19 2.18 113 – 113 26.89 26.26

GEV207_R0400_0470 1b 0.1 56.62 333.83 1.27 2.11 2500 2 -1 30.72 181.13 0.69 1.44 87683 90183 26.30 27.80

GEV207_R0400_0471 1b -1 39.22 233.11 0.95 0.86 1155 – 1155 25.80 24.65

GEV207_R0400_0536 3 0.1 33.08 203.12 0.76 *) 6.1 164898 – 164898 26.89 27.80


Block 1 Block 2




Total Cycles

E_tens [GPa]

E_compr [GPa]

GEV207_R0400_0540 1 0.1 55.97 343.06 1.28 *) 2.11 2500 3 0.1 32.88 201.53 0.75 *) 6.1 31820 34320 26.89 27.80

GEV207_R0400_0704 2 -1 30.23 183.36 0.70 1.44 25000 1b 10 52.70 319.65 1.20 2.18 3393 28393 27.07 26.31

GEV207_R0400_0706 1b -1 38.75 234.85 0.87 *) 0.86 1868 – 1868 26.89 27.80

GEV207_R0400_0742 1 0.1 32.88 198.48 0.74 *) 6.1 500000 1b 0.1 55.97 337.86 1.26 *) 2.11 4274 504274 26.89 27.80

GEV207_R0400_0743 1 0.1 33.01 198.47 0.74 *) 6.1 500000 1b 0.1 56.20 337.90 1.26 *) 2.11 3699 503699 26.89 27.80

GEV207_R0400_0744 1 0.1 55.53 340.48 1.27 *) 2.11 2500 3 0.1 32.62 200.01 0.74 *) 6.1 2356519 2359019 26.89 27.80

GEV207_R0400_0745 1b 0.1 56.20 349.85 1.30 *) 2.11 2274 – 2274 26.89 27.80

GEV207_R0400_0754 3 10 44.30 280.26 1.01 *) 3.15 500000 1b 10 53.11 335.98 1.21 *) 2.18 61323 561323 26.89 27.80

Table 9: Overview of simple block tests MD2

6.2.2 Repeated block tests In the repeated block tests, the specimens were repeatedly tested at each loading condition up to 1% of their nominal fatigue life each. 27 repeated block tests were accomplished with in total 3.945.128 load cycles requiring 427 hours of testing time. 26 of these tests could be declared a valid test. Detailed information is given in the following table. For measurements of strain and modulus the same remarks are valid as mentioned in the paragraph before.

Block 1 Block 2




Total Cycles

E_tens [GPa]

E_compr [GPa]

GEV207_R0400_0542 1 0.1 55.97 345.72 1.29 *) 2.11 346 3 0.1 32.88 203.09 0.76 *) 6.1 60000 60346 26.59 27.80

GEV207_R0400_0543 1 0.1 56.20 345.76 1.29 *) 2.11 308 3 0.1 33.01 203.09 0.76 *) 6.1 60000 60308 26.89 27.80

GEV207_R0400_0544 1b -1 39.14 240.33 0.89 *) 0.86 412 3 -1 22.47 137.97 0.51 *) 2.57 80000 80412 26.89 27.80

GEV207_R0400_0545 1b -1 39.22 242.22 0.90 *) 0.86 550 3 -1 22.52 139.08 0.52 *) 2.57 105910 106460 26.89 27.80

GEV207_R0400_0546 1b 10 53.28 324.63 1.17 *) 2.18 6850 3 10 44.44 270.77 0.97 *) 3.15 1370004 1376854 - 27.80


Block 1 Block 2




Total Cycles

E_tens [GPa]

E_compr [GPa]

GEV207_R0400_0697 1b 10 52.77 314.92 1.20 2.18 36100 2 10 48.77 291.05 1.11 2.55 361048 397148 - 26.29

GEV207_R0400_0698 2 -1 30.19 183.34 0.71 1.44 60500 1b 10 52.64 319.67 1.24 2.18 6324 66824 26.45 25.07

GEV207_R0400_0699 2 -1 30.31 183.33 0.69 1.44 13000 1b 0.1 55.86 337.87 1.28 2.11 1251 14251 26.77 26.14

GEV207_R0400_0700 2 -1 30.30 180.61 0.69 1.44 11500 1b 0.1 55.84 332.84 1.27 2.11 1123 12623 26.51 25.75

GEV207_R0400_0702 1b 0.1 55.91 337.90 1.26 *) 2.11 2074 2 0.1 44.38 268.22 1.00 *) 3.34 20500 22574 26.89 -

GEV207_R0400_0703 2 10 48.79 295.45 1.15 2.55 20000 2 0.1 44.29 268.18 1.04 3.34 19959 39959 26.58 24.87

GEV207_R0400_0705 2 10 48.52 295.48 1.12 2.55 31000 2 0.1 44.04 268.20 1.02 3.34 30718 61718 27.13 25.56

GEV207_R0400_0707 1b -1 38.91 233.11 0.87 *) 0.86 1200 3 -1 22.34 133.84 0.50 *) 2.57 231757 232957 26.89 27.80

GEV207_R0400_0710 1b 10 52.62 321.14 1.16 *) 2.11 8100 3 10 43.89 267.86 0.96 *) 1.76 162000 170100 - 27.80

GEV207_R0400_0711 1b -1 38.75 234.85 0.87 *) 0.86 1150 2 -1 30.25 183.33 0.68 *) 1.44 11833 12983 26.89 27.80

GEV207_R0400_0715 1b 10 53.32 316.34 1.21 2.18 5500 3 10 44.48 263.90 1.01 3.15 1100018 1105518 - 26.10

GEV207_R0400_0716 1b -1 39.00 237.38 0.87 0.86 5250 2 -1 30.44 185.28 0.68 1.44 52867 58117 27.63 26.98

GEV207_R0400_0746 1 0.1 55.97 351.16 1.31 *) 2.11 300 3 0.1 32.88 206.29 0.77 *) 6.1 59029 59329 26.89 27.80

GEV207_R0400_0747 2 -1 30.30 186.16 0.66 1.44 38000 1b 10 52.83 324.59 1.15 2.18 4133 42133 28.82 27.62

GEV207_R0400_0748 1b -1 38.90 239.17 0.85 0.86 1700 2 -1 30.37 186.72 0.66 1.44 17256 18956 28.49 27.73 GEV207_R0400_0750 2 -1 30.20 189.65 0.66 1.44 21500 1b 10 52.67 330.75 1.16 2.18 2403 23903 28.89 28.30 GEV207_R0400_0751 1b 10 52.79 329.67 1.24 2.18 17050 2 10 48.79 304.69 1.15 2.55 170500 187550 - 25.52 GEV207_R0400_0752 1b 0.1 55.77 356.22 1.32 *) 2.11 650 2 0.1 44.27 282.76 1.05 *) 3.34 6781 7431 26.89 - GEV207_R0400_0753 1b 0.1 55.91 355.12 1.32 *) 2.11 550 2 0.1 44.38 281.89 1.05 *) 3.34 5432 5982 26.89 - GEV207_R0400_0755 1b 10 52.98 330.19 1.19 *) 2.18 2600 1b 0.1 56.00 349.01 1.30 *) 2.11 2587 5187 26.89 27.80 GEV207_R0400_0756 1b 10 53.11 331.25 1.19 *) 2.18 1700 1b 0.1 56.13 350.08 1.30 *) 2.11 1695 3395 26.89 27.80

Table 10: Overview of repeated block tests MD2


6.2.3 Load spectra tests Since DLR concentrated due to severe software problems on the accomplishment of block tests and the general delay in the project, only a very limited number of load spectra tests could be done. 7 tests were done with the WISPER load spectra, from which 5 valid test re-sults could be obtained.

Load Stress Loading rate Coupon-ID Load spectra

[kN] [MPa] Passes

[(kN/mm)/s] GEV207_R0400_0532 Wisper 53.75 330.02 1.25 14.38

GEV207_R0400_0738 Wisper 53.43 324.98 16.66 14.38

GEV207_R0400_0528 Wisper 53.62 334.69 1.43 14.38

GEV207_R0400_0725 Wisper 53.20 322.12 3.64 14.38

GEV207_R0400_0527 Wisper 45.70 286.38 7.28 16.92

Table 11: Overview of test results WISPER load spectra

7 Results achieved in Phase 2

7.1 Constant amplitude testing Due to the significant delay in Phase 1 of the project, only a very limited number of tests with the alternative material could be accomplished in Phase 2. The variable amplitude testing had completely to be skipped, for constant amplitude testing only the establishment of one single S-N curve was possible.

7.1.1 MD4, R=0.1 At R=0.1 in total 10 specimens of the MD alternative material were tested with 10 valid re-sults. The results showed very low scatter. For all specimens failure was initiated by the debonding of the tabs and fracture occurred in or nearby the load introduction. Initial strain and tensile modulus were not directly determined. For strain calculation the ten-sile modulus available in OptiDat was used.



[GPa] [Hz] GEV307_R0400_0050 0.1 57.00 334.84 1,18 *) 6408 28.47 2.11

GEV307_R0400_0049 0.1 45.68 267.78 0,94 *) 64868 28.47 3.34

GEV307_R0400_0048 0.1 33.31 194.34 0,68 *) 1946304 28.47 6.10

GEV307_R0400_0047 0.1 57.09 327.94 1,15 *) 6754 28.47 2.11

GEV307_R0400_0046 0.1 45.08 266.57 0,94 *) 51634 28.47 3.34

GEV307_R0400_0045 0.1 57.07 334.84 1,18 *) 7356 28.47 2.11

GEV307_R0400_0044 0.1 45.19 269.82 0,95 *) 42044 28.47 3.34

GEV307_R0400_0043 0.1 45.49 268.59 0,94 *) 46507 28.47 3.34

GEV307_R0400_0042 0.1 33.43 199.38 0,70 *) 956059 28.47 6.11

GEV307_R0400_0041 0.1 33.38 194.08 0,68 *) 1377528 28.47 6.10

GEV307_R0400_0051 0.1 26.55 156.86 0,55 *) 11116738 28.47 9.68

Table 12: Overview of test results MD (alternative) R=0.1


S-N-Curve MD-Data (alternative)R=0.1

0

100

200

300

400

500

600

700

800

900

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]

Test Results

Mean ValueSendeckyj


Figure 10: MD4 (alternative) R=0.1

7.2 Variable amplitude testing No variable amplitude testing was performed in Phase 2.


8 Comparison of results In the following two paragraphs the results achieved at DLR are compared to the results of the other labs to get some information about the comparability of results obtained in different labs using various test rigs. The comparison can only be done for the test results achieved within Phase I of the project.

8.1 Constant amplitude testing The following figures show all S-N curves for which DLR contributed data points. Obviously no significant difference in comparison to the results of the other labs could be seen. There-fore the results obtained in different labs using various test rigs are comparable and can be pooled. This can also be shown by comparing the parameters of the statistical evaluation. Comparing the parameters for the evaluation according Sendeckyj, there can differences be seen for the shape parameters α and β, as well as for parameter C. The first of them, α, is a measure for the scatter and varies naturally for a different set of test results. The equivalent static strength is represented by β, and is strongly influenced by the value of C. For C<1, the curve flattens when the applied stress reaches the equivalent static strength. C=1 is the classical power law definition, and for C>1 the curve is very steep. These 3 parameters are generally strongly dependent of the set of test results used for the evaluation. Additionally a numeric procedure is used to optimise the values which can yield differences too. The fatigue slope S is not that sensitive, if a sufficient number of test results is used for the evaluation. For the available data it can be shown that the fatigue slope S determined with the test re-sults of all labs, is generally very close to that value determined with DLR-data only. The same trend can be observed using a simple linear regression for modelling the S-N curve. Additionally, the fatigue slopes determined using the Weibull method of Sendeckyj and linear regression are pretty close. This offers the possibility to use a simple linear regression, which is basically available in common spreadsheet tools, instead of a complex numeric tool for determination of Weibull parameters. Nevertheless, the Sendeckyj model is more suited for a more correct representation of the physical behaviour of the material, especially for low num-bers of load cycles. But this region is generally of less importance of fatigue analysis.


S-N-Curve UD-DataR=-1

0

100

200

300

400

500

600

0 1 2 3 4 5 6 7

Log N

Ap

plie

d S

tres

s [M

Pa]

Test results other labs

Test results DLR

Mean Value Sendeckyj

Figure 11: UD2, R=-1 – Comparison to other labs

Sendeckyj Linear regression α β C S K b

All Labs 14.2389 565.5472 0.0300 0.1000 840.1382 0.1146 DLR 50.5413 935.4774 1.0000 0.1229 752.8464 0.1021

Table 13: UD2, R=-1 – Comparison to other labs (statistical evaluation)


S-N-Curve MD-DataR=-1

0

100

200

300

400

500

600

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]


Test results DLR


Figure 12: MD2, R=-1 – Comparison to other labs


All Labs 11.6051 529.4275 1.0000 0.1004 480.5506 0.0961 DLR 25.8556 518.2620 0.5000 0.1024 596.4077 0.1111

Table 14: MD2, R=-1 – Comparison to other labs (statistical evaluation)



0

100

200

300

400

500

600

700

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]


Test results DLR


Figure 13: MD2, R=0.1 – Comparison to other labs


All Labs 26.9797 649.7263 0.2500 0.0950 728.3801 0.0954 DLR 59.4094 659.5317 0.2188 0.0961 773.3295 0.0992

Table 15: MD2, R=0.1 – Comparison to other labs (statistical evaluation)



0

100

200

300

400

500

600

700

800

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]


Test results DLR


Figure 14: MD2, R=0.5 – Comparison to other labs


All Labs 14.3996 698.2247 0.9976 0.0732 718.0875 0.0789 DLR 14.2471 672.0000 0.5000 0.0727 638.5436 0.0671

Table 16: MD2, R=0.5 – Comparison to other labs (statistical evaluation)



0

100

200

300

400

500

600

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]


Test results DLR


Figure 15: MD2, R=-0.4 – Comparison to other labs


All Labs 12.3454 537.7059 0.0750 0.1080 672.8423 0.1075 DLR 9.7399 729.000 0.5000 0.1184 652.0004 0.1068

Table 17: MD2, R=-0.4 – Comparison to other labs (statistical evaluation)



0

100

200

300

400

500

600

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]


Test results DLR


Figure 16: MD2, R=-2.5 – Comparison to other labs


All Labs 10.3374 522.4943 1.0000 0.0640 530.3740 0.0699 DLR 12.4929 458.0000 0.2000 0.0685 595.2585 0.0873

Table 18: MD2, R=-2.5 – Comparison to other labs (statistical evaluation)


S-N-Curve MD-DataR=10

0

50

100

150

200

250

300

350

400

450

0 1 2 3 4 5 6 7 8 9

Log N

Ap

plie

d S

tres

s [M

Pa]


Test results DLR


Figure 17: MD2, R=10 – Comparison to other labs


All Labs 18.4125 413.4960 1.0000 0.0281 399.3984 0.0274 DLR 35.9900 425.0000 1.0000 0.0326 413.8855 0.0316

Table 19: MD2, R=10 – Comparison to other labs (statistical evaluation)

For the constant amplitude tests of the MD alternative material at R=0.1, no results of other labs were available for comparison.

8.2 Variable amplitude testing

8.2.1 Simple block tests For the simple block tests the comparison of the DLR results to those of WMC show that there is obviously large scatter, which makes an analysis more difficult. Furthermore the number of test results for each test type is low. Generally there is no clear difference be-tween the results, but tests at WMC seems to have a slightly longer lifetime. For the tests of type A, the lifetime achieved at WMC is definitely higher than for DLR tests. But this can pos-sibly be explained by the fact, that the specimens were made of very different plates (plate 176 for WMC, plates 79/80 for DLR). Additionally tests of type A have R=10 as R-ratio for both blocks, that means pure compressive loading. These tests show typically more scatter.


Simple Block Tests Type A

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1 2 3 4 5 6 7

Test

N

Test Results WMC

Test Results DLR

Figure 18: MD2, Simple Block Tests Type A – Comparison to WMC lab

Simple Block Tests Type B

0

100.000

200.000

300.000

400.000

500.000

600.000

700.000

1 2

Test

N

Test Results WMC

Test Results DLR

Figure 19: MD2, Simple Block Tests Type B – Comparison to WMC lab


Simple Block Tests Type E

0

10.000

20.000

30.000

40.000

50.000

60.000

70.000

1 2 3 4 5 6

Test

N

Test Results WMC

Test Results DLR

Figure 20: MD2, Simple Block Tests Type E – Comparison to WMC lab

Simple Block Tests Type F

0

100.000

200.000

300.000

400.000

500.000

600.000

1 2 3 4

Test

N

Test Results WMC

Test Results DLR

Figure 21: MD2, Simple Block Tests Type F – Comparison to WMC lab


Simple Block Tests Type G

0

20.000

40.000

60.000

80.000

100.000

120.000

1 2 3 4 5 6

Test

N

Test Results WMC

Test Results DLR

Figure 22: MD2, Simple Block Tests Type G – Comparison to WMC lab

Simple Block Tests Type H

0

100.000

200.000

300.000

400.000

500.000

600.000

1 2 3 4 5 6

Test

N

Test Results WMC

Test Results DLR

Figure 23: MD2, Simple Block Tests Type H – Comparison to WMC lab


Simple Block Tests Type I

0

1.000

2.000

3.000

4.000

5.000

6.000

7.000

8.000

9.000

10.000

1 2 3 4

Test

N

Test Results WMC

Test Results DLR

Figure 24: MD2, Simple Block Tests Type I – Comparison to WMC lab

Simple Block Tests Type J

0

100.000

200.000

300.000

400.000

500.000

600.000

1 2 3 4

Test

N

Test Results WMC

Test Results DLR

Figure 25: MD2, Simple Block Tests Type I – Comparison to WMC lab


8.2.2 Repeated block tests

Repeated Block Tests Type A

0

200.000

400.000

600.000

800.000

1.000.000

1.200.000

1 2 3

Test

N

Test Results WMC

Test Results DLR

Figure 26: MD2, Repeated Block Tests Type A – Comparison to WMC lab

Repeated Block Tests Type C

0

10.000

20.000

30.000

40.000

50.000

60.000

70.000

1 2 3

Test

N

Test Results WMC

Test Results DLR

Figure 27: MD2, Repeated Block Tests Type C – Comparison to WMC lab


Repeated Block Tests Type D

0

50.000

100.000

150.000

200.000

250.000

300.000

350.000

1 2 3 4 5

Test

N

Test Results WMC

Test Results DLR

Figure 28: MD2, Repeated Block Tests Type D – Comparison to WMC lab

Repeated Block Tests Type E

0

5.000

10.000

15.000

20.000

25.000

1 2 3

Test

N

Test Results WMC

Test Results DLR

Figure 29: MD2, Repeated Block Tests Type E – Comparison to WMC lab


Repeated Block Tests Type F

0

20.000

40.000

60.000

80.000

100.000

120.000

140.000

160.000

180.000

1 2 3

Test

N

Test Results WMC

Test Results DLR

Figure 30: MD2, Repeated Block Tests Type F – Comparison to WMC lab

Repeated Block Tests Type G

0

2.000

4.000

6.000

8.000

10.000

12.000

14.000

16.000

1 2 3

Test

N

Test Results WMC

Test Results DLR

Figure 31: MD2, Repeated Block Tests Type G – Comparison to WMC lab


Repeated Block Tests Type H

0

10.000

20.000

30.000

40.000

50.000

60.000

70.000

80.000

1 2 3

Test

N

Test Results WMC

Test Results DLR

Figure 32: MD2, Repeated Block Tests Type H – Comparison to WMC lab

Repeated Block Tests Type I

0

1.000

2.000

3.000

4.000

5.000

6.000

7.000

8.000

9.000

10.000

1 2 3

Test

N

Test Results WMC

Test Results DLR

Figure 33: MD2, Repeated Block Tests Type I – Comparison to WMC lab

For the repeated block tests the same observations can be made as for the simple block tests.


8.2.3 Load spectra tests For the limited number of load spectra tests no clear statement can be made concerning the comparability of results. Additionally the tests show large scatter. Therefore it can be as-sumed that there is no significant lab influence on the results.

WISPER Load Spectra TestsMD

0

50

100

150

200

250

300

350

400

0 10 20 30 40 50 60 70 80 90 100

Spectrum passes

Ap

plie

d S

tres

s [M

Pa]

Test Results other labs

Test Results DLR

Figure 34: MD2, Wisper – Comparison to other labs

9 Summary and Conclusions An extensive experimental program containing constant and variable amplitude tests was accomplished within the frame of the ‘OPTIMAT BLADES’ project. Constant amplitude tests were performed to characterize the fatigue behaviour of the investigated material and as in-put for a detailed analysis of lifetime prediction methodologies. For this purpose these fatigue tests were performed at multiple R-ratios. The comparison of the results achieved at DLR with the results of other labs show a good agreement. Therefore the data of all labs can be pooled and the reliability increased. The influence of different loading sequences and load spectra was investigated with numer-ous variable amplitude tests. Unfortunately these tests showed large scatter which made a reliable analysis very difficult. The lab-to-lab comparison of these results can therefore be not exact and should be taken as a trend.


10 References [1] Torben K. Jacobsen, Reference material (Optimat) - Glass-Epoxy material, LM Glasfiber

A/S, doc. OB_SC_R001 rev. 1, 29.01.2003

[2] Ch.W. Kensche et al., Detailed plan of action Task Group 1, DLR, doc. OB_TG1_O002 rev. 6, 23.07.2004

[3] Ch.W. Kensche et al., Detailed plan of action for Phase 2, Task Group 1, DLR, doc. OB_TG1_O006 rev. 0, 12.09.2005

[4] Olaf Krause and Theodore P. Philippidis, General Test Specification, DLR, doc. OB_TC_R014 rev. 5, 07.09.2005

[5] Olaf Krause, Test specification for load spectra tests, DLR, doc. OB_TG1_R021 rev. 2, 22.07.2005

summary fatigue test report - wmc · summary fatigue test report ob ... all tests were accomplished...

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