Studies on the Influence of Through-the-Thickness Reinforcement on Low-Velocity and High Strain Rate Response of Woven S2-Glass/Vinyl Ester Composite

Abstract

Due to their inherent weakness in the thickness direction, laminated fiber reinforced composites are susceptible to undergo large delamination damage as well as splitting when subjected to transverse loading and microbuckling under in-plane compressive loading. In the current work, an effort is made to improve the transverse strength by providing discrete 3D reinforcement in the form of pins and stitching the laminate in the thickness direction. The effectiveness of the 3D reinforcement is compared with 2D-Plain laminates. The laminates were made of 15 layers of 2 × 2 twill weave S2-glass fabric and vinyl ester C-50 resin system. Specimens of size 75 × 100mmwere subjected to low-velocity impact loading at energy levels of 20, 30 and 40 joules. The effectiveness of 3D-reinforcement to in-plane dynamic loading was studied using a Compression Split Hopkinson’s Pressure Bar at three different strain rates of 327/s, 436/s and 544/s using cubic samples of size 6.0mm. The stitched samples were subjected to high strain rate loading in two configurations. In the first, the sample (referred to as 3D-Stitch1) had stitching along the loading direction at the center while in the second; the sample (referred to as 3D-Stitch2) had an additional stitch line along the width at the center. The results of the study indicate that, reinforcement using stitching confines the delamination growth under low-velocity impact loading. Reinforcement in the form of pins did not show considerable improvement in the damage containment. However, under high strain rate compressive loading, 3D-Stitch1 and 3D-Pin reinforced laminates demonstrated higher compressive strengths at the strain rates of 327/s and 436/s. Stitch2 and 2D-Plain samples, in comparison, exhibited lower strength. Both 2D-Plain and 3D-Pin reinforced laminates exhibited increasing strength with the increase in the strain rate. Whereas, stitched laminates exhibited increase in strength from the strain rate of 327/s to 436/s before dropping in magnitude at 544/s. Thiswas attributed to the localized damage in the fabric due to piercing of the needle during stitching resulting in resin pooling.

Keywords

damage resistance stitching pin reinforcement low-velocity impact high strain rate loading

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References

1. Abrate, S.

“Impact on Laminated Composite Materials,”

ASME Applied Mechanics Review, Vol. 44, No. 4, April 1991, pp. 155-190.

2. Cantwell, W. J. and Morton, J.

“The Impact Resistance of Composite Materials—A Review,”

Composites, Vol. 22, No. 5, Sept. 1991, pp. 347-362.

3. Cordell, T. M. and Sjoblom, P. O.

“Low-Velocity Impact Testing of Composites,”

Damage Tolerance of Composites, Proceedings of American Society for Composites, First Technical Conference, Oct. 7-9, 1986, Dayton, Ohio, Technomic Publishing Co. Inc., Lancaster, Pennsylvania, USA, pp. 297-312.

4. Harding, J.

“Impact Damage in Composite Materials,”

Science and Engineering of Composite Materials, Vol. 1, 1989, pp. 41-68.

5. Elber, W. “Failure Mechanics in Low-Velocity Impacts on Thin Composite Plates,” NASATechnical Paper 2152, 1983.

6. Liu, S. and Chang, F. K.

“Matrix Cracking Effect on Delamination Growth in Composite Laminates Induced by a Spherical Indenter,”

Journal of Composite Materials, Vol. 28, No. 10, 1994, pp. 940-977.

7. Liu, S.

“Delamination and Matrix Cracking of Cross-Ply Laminate Due to Spherical Indentor,”

Composite Structures, Vol. 25, 1993, pp. 257-265.

8. Guild, F. J. , Hogg, P. J. and Prichard. J. C.

“A Model for the Reduction in Compressive Strength of Continuous Fiber Composites after Impact Damage,”

Composites, Vol. 24, No. 4, 1993, pp. 333-339.

9. Hull, D. and Shi, Y. B.

“Damage Mechanisms Characterization in Composite Damage Tolerance Investigations,”

Composite Structures, Vol. 23, 1993, pp. 99-120.

10.

10. Jones, R. and Baker, A. A.

“Compressive Strength of Impact Damaged Graphite Epoxy Composites,”

Proceedings 3rd International Conference on Composite Structures, Scotland, Sept. 1985, Marshall, I. H (Ed.), Elsevier, 1985, pp. 402-414.

11.

11. Prichard, J. C. and Hogg, P. J.

“The Role of Impact Damage in Post-Impact Compression Testing,”

Composites, Vol. 21, No. 6, 1990, pp. 503-511.

12.

12. Wyrick, D. and Adams, D.

“Residual Strength of Carbon Epoxy Composite Material Subjected to Repeated Impacts,”

Journal of Composite Materials, Vol. 22, No. 8, 1988, pp. 749-765.

13.

13. Hosur, M. V. “Studies on Damage and Residual Compressive Strength of Carbon Fiber Reinforced Plastic Laminates Subjected to Low-Velocity Impact,” PhD Thesis, Indian Institute of Science, Bangalore, India, 1995.

14.

14. Daniel, I. M. and Liber, T.

“Testing of Fiber Reinforced Composites at High Strain Rates,”

Proceedings of 2nd International Conference on Composites Materials (ICCM/2), 1978, pp. 1003-1018.

15.

15. El-Habak, A. M. A.

“Compressive Resistance of Unidirectional GFRP under High Strain Rate of Loading,”

Journal of Composites Technology and Research, JCTRER, Vol. 15, No. 4, 1993, pp. 311-317.

16.

16. Powers, B. M. and Vinson, J. R. “High Strain Rate Effects in Materials in Sandwich Construction,” Sandwich Construction, 3rd Ed., Allen, H. G. , Ed., Engineering Materials Advisory Services, Ltd., England, 1996, pp 769-778.

17.

17. Powers, B. M. , Vinson, J. R. , Wardle, M. and Scott B.

“High Strain Rate Effects on Two AS4 Graphite Fiber Polymer Matrix Composites,”

ASME Aerospace Division Board AD-48, High Strain Rate Effects on Polymer, Metal, and Ceramic Matrix Composites and Other Advanced Materials, 1995, pp. 179-189.

18.

18. Rodriguez, J. , Chocron, I. S. , Martinez, M. A. and Sanchez-Galvez, V.

“High Strain Rate Properties of Aramid and Polyethylene Woven Fabric Composites,”

Composites Part B, Engineering, Vol. 27, No. 2, 1996, pp. 147-154.

19.

19. Waas, A. M. , Takeda, N. , Yuan, J. and Lee, S. H.

“Static and Dynamic Compressive Behavior of Glass Fiber Reinforced Unidirectional Composites,”

Proceedings of the 12th Annual Technical Conference of American Society for Composites, 1997, pp. 552-561.

20.

20. Woldenbet, E. and Vinson. J. R.

“Effect of Specimen Geometry in High Strain Rate Testing of Graphite/Epoxy Composites,”

Proceedings of 38th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, Vol. 2, 1997, pp. 927-934.

21.

21. Preissner, E. C. , Woldesenbet, E. and Vinson. J. R.

“An Examination of High-Strain Rate Compressive Stress-Strain Behavior of a Kevlar/Epoxy Composite,”

Proceedings of the 38th AIAA/ASME/ ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, Vol. 2, 1997, pp. 935-944.

22.

22. Bucknell, C. B.

“Approaches to Toughness Enhancement,”

Advanced Composites, Partridge, I. (Ed.), Elsevier Science Publishers Ltd., London, 1989, pp 145-161.

23.

23. Beaumont, P. W. R. , Riewald, P. G. and Zweben, C.

“Methods of Improving the Impact Resistance of Composite Materials,”

Foreign Object Impact Damage to Composites. ASTM STP 568, American Society for Testing and Materials, 1974, pp. 134-158.

24.

24. “Advanced Impact Resistant Multidimensional Composites,” NASA CR No. N0019-77-C-0430, Jan. 1979.

25.

25. “Standard Test Method for Apparent Interlaminar Shear Strength of Parallel Fiber Composites by Short-Beam Method,” D2344, Annual Book of ASTM Standards, American Society for Testing and Materials.

26.

26. Nemat-Nasser, S. , Isaacs, J. B. and Starrett. J.

“Hopkinson Techniques for Dynamic Recovery Experiments,”

Proc. R. Soc. London A, 1991, Vol. 435, pp. 371-391.

27.

27. Nemat-Nasser, S.

“New Frontiers in Dynamic Recovery Testing of Advanced Composites: Tailoring Microstructure for Optimal Performance,”

JSME International Journal, Series I, Vol. 34, No. 2, 1991, pp. 111-122.

28.

28. Seirakowski, R. L. and Chaturvedi, S. K. “Dynamic Loading and Characterization of Fiber Reinforced Composites”, 1997, A Wiley Interscience Publication, New York.