Stiffness of Smart Composites with Shape Memory Alloy Fibers in the Presence of Matrix Cracks

Abstract

The paper presents a methodology for evaluating the effective stiffness of unidirectional composite materials with shape memory alloy (SMA) fibers in the presence of matrix cracks. The solution is obtained for the case where SMA fibers in the intact composite are in the austenitic phase. However, elevated stresses in the sections of SMA fibers adjacent to the crack planes cause the martensitic transformation affecting the stiffness of the material. The solution has to account for thermal residual stresses in SMA and "ordinary" fibers and in the matrix. The order of magnitude of these stresses is calculated in the paper for two representative composite systems. As follows from the numerical examples, thermal residual stresses in the SMA fibers increase proportionally to their volume fraction but remain relatively small. However, thermal stresses in the matrix may reach rather high values reducing the strength of the matrix by a significant factor.

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References

Ahn, B.K. , Curtin, W.A. , Parthasarathy, T.A. and Dutton, R.E. , 1998. "Criteria for Crack Deflection/Penetration Criteria for Fiber-Reinforced Ceramic Matrix Composites," Composites Science and Technology, 58, pp. 1775-1784.

Birman, V. , 1997. "Review of Mechanics of Shape Memory Alloy Structures," Applied Mechanics Reviews, 50, pp. 629-645.

Gibson, R.F. , 1994. Principles of Composite Material Mechanics, McGraw-Hill, New York.

Hebda, D.A. and White, S.R. , 1995. "Effect of Training Conditions and Extended Cycling on Nitinol Two-Way Shape Memory Behavior," Smart Materials and Structures, 4, pp. 298-304.

Kuo, W.-S. and Chou, T.-W. , 1995. "Multiple Cracking of Unidirectional and Cross-Ply Ceramic Matrix Composites," Joumal of the American Ceramic Society, 78, pp. 745-755.

Liang, C. and Rogers, C.A. , 1990. "One-Dimensional Thermomechanical Constitutive Relations for Shape Memory Materials," Journal of Intelligent Material Systems and Structures, 1, pp. 207-234.

Paine, J.S.N. and Rogers, C.A. , 1994. "Improved Impact Damage Resistance in Adaptive Shape Memory Alloy Hybrid Composite Materials," Smart Structures and Intelligent Systems, Ed. Hagood, N.W., Vol. 2190, pp. 402-409, SPIE (The Int. Soc. Optical Engineering).

Pryce, A.W. and Smith, P.A. , 1993. "Matrix Cracking in Unidirectional Ceramic Matrix Composites under Quasi-Static and Cyclic Loading," Acta Metallurgica et Materialia, 41, pp. 1269-1281.

Schetky, L.McD. , 1992. "Role of Shape Memory Alloy in Smart/Adaptive Structures," Shape-Memory Materials and Phenomena-Fundamental Aspects and Applications, Eds. Liu, C.T. et al., Vol. 246, pp. 299-307, Materials Research Society.

10.

Schwartz, M.M. , 1997. Composite Materials, Vol. 1: Properties, Nondestructive Testing, and Repair Prentice Hall, Upper Saddle River.

11.

White, S.R. , Whitlock, M.E. , Ditman, J.B. , and Hebda, D.A. , 1993. "Manufacturing of Adaptive Graphite/Epoxy Structures with Embedded Nitinol Wires," Adaptive Structures and Material Systems, Eds. G.P. Carman and E. Garcia , pp. 71-79, ASME, New York.