Modified Short Beam Shear Test for Measurement of Interlaminar Shear Strength of Composites

Abstract

A modified short beam shear test was proposed to measure interlaminar shear strength (ILSS) of fiber reinforced carbon-carbon composites (CCC). The direct loading in the short beam shear (SBS) test is replaced by an indirect loading through a rubber pad and an aluminum seat. This loading reduced flexure stresses to less than one fourth of the SBS test and eliminated transverse shear stress concentration under the load point. Both beam and contact finite element analyses were conducted to validate the proposed method. The finite element analysis showed that the ILSS calculated from beam equation overestimates the strength by 5% for shear flexible composites. This reduction was found to be the same for both polymeric and carbon matrix composites. The test data confirmed the interlaminar shear failure and very low data scatter in measured strength. The measured ILSS of T300 CCC was 2.68 ksi and it is one of the highest values reported in literature.

Keywords

composite material carbon-carbon composites interlaminar shear strength modified short beam shear test

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References

1. (1999). Short Beam Method, Annual Book of ASTM Standards, American Society for Testing and Materials, Philadelphia, PA.

2. Browning, C. E. and Whitney, M. J. (1983). A Four-point Test for Graphite/Epoxy Composites. In: Browning, C. E. (ed.), Composite Materials: Quality Assurance and Processing, ASTM STP 797, American Society for Testing and Materials, Philadelphia, PA.

3. Berg, C. A. , Tirosh, J. and Israeli, M. (1972). Analysis of Short Beam Bending of Fiber Reinforced Composites, Composite Materials: Testing and Design (Second Conference), ASTM STP 497, pp. 206–218, American Society for Testing and Materials, Philadelphia, PA.

4. Cui, W. C. , Wisnom, M. R. and Jones, N. (1992). Failure Mechanisms in Three and Four Point Short Beam Bending Tests of Unidirectional Glass/Epoxy, Journal of Strain Analysis, 27(4): 235–243.

5. Xie, M. and Adams, D. F. (1995). Contact Finite Element Modeling of the Short Beam Shear Test for Composites Materials, Computers and Structures, 57(2): 183–191.

6. Whitney, J. W. (1992). Reflections on the Development of Test Methods for Advanced Composites. In: Glen C. Grimes (ed.), Composite Materials: Testing and Design, ASTM STP 1120, Vol. 10: pp. 7–16, American Society for Testing and Materials, Philadelphia, PA.

7. Emehel, T. C. and Shivakumar, K. N. (1997). Tow Collapse Model for Compression Strength of Textile Composites, Journal of Reinforced Plastics and Composites, 16(1): 86–101.

8. Rahhal, W. F. and Kotlensky, W. V. (1992). Modified Short-Beam Shear Test, Carbon, 30(3): 385–389.

9. Short, S. R. (1995). Characterization of Interlaminar Shear Failures of Graphite/Epoxy Composite Materials, Composites, 26: 431–449.

10.

10. Popov, E. P. (1968). Introduction to Mechanics of Solids, Prentice-Hall, Eaglewood Cliffs, NJ.

11.

11. Shivakumar, K. N., Abali, F. L., Suderesan, M. J., Sadler, R. L. and Cunningham, A. (1999). An Apparatus and Method for Forming Densified Carbon/Carbon Composites, U. S Patent No. 6,325,608.

12.

12. Abali, F. , Shivakumar, K. and Sadler, R. (2000). Resin Transfer Molding Based Carbon/Carbon Composites, 45th International SAMPE Symposium, Long Beach, CA, 21–25 May.

13.

13. Shivakumar, K. N. and Elber, W. (1984). Delamination Growth Analysis in a Quasi-Isotropic Laminate Under Loads Simulating Low-Velocity Impact, NASA TM-85819.