In this study, a cruciform-shaped test specimen is utilized to characterize the fiber–matrix interface under transverse and combined (tensile and shear) loading. We first present an overview of past references of how the cruciform geometry is optimized to promote interfacial failure. We then discuss a modification of the cruciform specimen where face-sheets are adhesively bonded to reinforce the sample. These face-sheets serve a twofold purpose, namely, to prevent premature failure in the fillet region and to encourage debond initiation at the center of the gage length. Finally, an off-axis cruciform geometry, in which the wings of the cruciform sample are inclined at an angle with respect to the loading direction, is introduced to characterize the fiber–matrix interface under combined transverse and shear loading. Using the measured value of applied stress at debond initiation, and the evaluated stress concentration factor at the fiber–matrix interface, a mixed-mode failure envelope is then constructed in the normal-shear stress space, and a quadratic failure criterion is proposed.
Get full access to this article
View all access options for this article.
References
1.
1. Chepolis, W. M. and Erturk, T. (1995). Fiber Twist Test: A New Technique to Measure Composite Interface Properties, Mat. Res. Soc. Symp. Proc., 365: 291–298.
2.
2. Melanitis, N., Galiotis, C., Teflow, P. L. and Davies, C. K. L. (1993). Interfacial Shear Stress Distribution in Model Composites: The Effect of Fibre Modulus, Comp. Sci. and Tech., 34: 289–303.
3.
3. Kelly, A. and Tyson, W. R. (1965). Tensile Properties of Fiber-Reinforced Metals: Copper/Tungsten and Copper/Molybdenum, J. Mech. and Phys. of Solids, 13: 329–350.
4.
4. Drzal, L. T., Rich, M. J., Camping, J. D. and Park, W. J. (1980). Interfacial Shear Strength and Failure Mechanisms in Graphite Fiber Composites, 35th Tech. Conf. Reinforced Plastics/Composites Inst., Section 20C, pp. 1–7.
5.
5. Mandell, J. F., Grande, D. H., Tsiang, T. H. and McGarry, F. J. (1986). Modified Microdebonding Test for Direct In-Situ Fiber/Matrix Bond Strength Determination in Fiber Composites, Composite Materials: Test and Design, ASTM STP 893, American Society for Testing and Materials, pp. 87–108.
6.
6. Ho, H. and Drzal, L. T. (1996). Evaluation of Interfacial Mechanical Properties of Fiber Reinforced Composites Using the Microindentation Method, Composites: Part A, 27A: 961–971.
7.
7. Netravali, A. N., Stone, D., Ruoff, S. and Topoleski, L. T. T. (1989). Continuous Micro-Indenter Push-Through Technique for Measuring Interfacial Shear Strength of Fiber Composites, Comp. Sci. and Tech., 34: 289–303.
8.
8. Laughner, J. W., Shaw, N. J., Bhatt, R. T. and Dicarlo, J. A. (1986). Simple Indentation Method for Measurement of Interfacial Shear Strength in SiC/Si3N4 Composites, Cer. Eng. and Sci. Proc., 7: 932-932.
9.
9. Warren, P. D., Mackin, T. J. and Evans, A. G. (1992). Design, Analysis, and Application of an Improved Push-Through Test for the Measurement of Interface Properties in Composites, Acta Metall. Mater., 40: 1243–1249.
10.
10. Bechel, V. T. and Sottos, N. R. (1998). Application of Debond Length Measurements to Examine the Mechanics of Fiber Pushout, J. Mechanics and Physics of Solids, 46(9): 1675–1697.
11.
11. Bechel, V. T. and Sottos, N. R. (1998). The Effect of Residual Stresses and Sample Preparation on Progressive Debonding During the Fiber Push-Out Test, Comp. Sci. and Tech., 58: 1741–1751.
12.
12. Tandon, G. P. and Pagano, N. J. (1998). Micromechanical Analysis of the Fiber Push-out and Re-Push Test, Comp. Sci. and Tech., 58: 1709–1725.
13.
13. Hu, S., Karpur, P., Matikas, T. E., Shaw, L. and Pagano, N. J. (1995). Free Edge Effect on Residual Stresses and Debond of a Composite Fiber/Matrix Interface, Mechanics of Composite Materials and Structures, 2: 215–225.
14.
14. Tandon, G. P., Kim, R. Y., Warrier, S. G. and Majumdar, B. S. (1999). Influence of Free Edge and Corner Singularities on Interfacial Normal Strength: Application in Model Unidirectional Composites, Composites, Part B: Engineering, 30: 115–134.
15.
15. Gundel, D. B., Majumdar, B. S. and Miracle, D. B. (1995). Evaluation of the Transverse Response of Fiber-Reinforced Composites Using a Cross-Shaped Sample Geometry, Scripta Metall., 33: 2057–2065.
16.
16. Warrier, S. G., Gundel, D. B., Majumdar, B. S. and Miracle, D. B. (1996). Stress Distribution in a Transversely Loaded Cross-Shaped Single Fiber SCS-6/Ti-6Al-4V Composite, Scripta Materialia, 34(2), 293–299.
17.
17. Warrier, S. G., Gundel, D. B., Majumdar, B. S. and Miracle, D. B. (1996). Interface Effects on Transversely Loaded Single-Fiber SCS-6/Ti-6Al-4V, Metall. Trans., 27A: 2035–2043.
18.
18. Majumdar, B. S., Gundel, D. B., Dutton, R. E., Warrier, S. G. and Pagano, N. J. (1998). Evaluation of the Tensile Interface Strength in Brittle Matrix Composite Systems, J. American Ceramic Society, 81(6): 1600–1610.
19.
19. Broutman, L. J. (1969). Measurement of the Fiber-Polymer Matrix Interfacial Strength, Interfaces in Composites, ASTM STP 452, American Society for Testing and Materials, pp. 27–41.
20.
20. Bechel, V. T. and Tandon, G. P. (2002). Characterization of Interfacial Failure Using a Reflected Light Technique, Experimental Mechanics, 42(2): 200–205.
21.
21. Tandon, G. P., Kim, R. Y. and Bechel, V. T. (2000). Evaluation of Interfacial Normal Strength in a SCS-0/Epoxy Composite Using Cruciform Specimens, Composites Science and Technology, 60: 2281–2295.
23. Sun, Y. and Singh, R. N. (2000). Determination of Fiber Bridging Stress Profile by Debond Length Measurement, Acta Mater., 48: 3607–3619.
24.
24. Bechel, V. T. and Tandon, G. P. (2002). Modified Cruciform Test for Application to Graphite/Epoxy Composites, Mechanics of Advanced Materials and Structures, 9: 1–17.
25.
25. Bechel, V. T. and Tandon, G. P. (2000). A Technique to Determine Processing Effects on Interfacial Adhesion. In: Proceedings of the IX SEM Congress on Experimental Mechanics, pp. 420–423.
26.
26. Bechel, V. T. unpublished work.
27.
27. Bechel, V. T., Tandon, G. P. and Kim, R. Y. (1999). Fiber/Matrix Interface Debond Length Measurements Under Transverse Loading in the Cruciform Test. In: Proceedings of the American Society of Composites, 14th Technical Conference, pp. 367–376.
28.
28. Tandon, G. P. and Bechel, V. T. (2000). Estimation of Interface Toughness in a Cruciform Specimen Under Transverse Loading. In: Proceedings of the American Society for Composites, 15th Technical Conference, pp. 1035–1042.
29.
29. Tandon, G. P., Kim, R. Y. and Bechel, V. T. (2001). Mixed-Mode Failure Criteria Using Cruciform Geometry, presented at 16th Annual Technical Conference of the American Society for Composites, Virginia Tech, Blacksburg, VA, September 9–12.
30.
30. Whitney, J. M. and Nuismer, R. J. (1974). Stress Fracture Criteria for Laminated Composites Containing Stress Concentrations, Journal of Composite Materials, 8: 253–265.
