A temperature-dependent constitutive model for fiber-reinforced ceramic matrix composites and structural stress analysis

A temperature-dependent constitutive model based on the continuum damage mechanics (CDM) theory is developed to model the stress/strain behavior of C/SiC composites. A formulation of Helmholtz free energy with initial modulus and tangent modulus is proposed to describe the bilinear constitutive behavior of such materials. The Lagrange interpolation is used to describe the relations between material parameters and temperature. The effect of temperature is introduced into the theoretical framework of continuum damage mechanics. The constitutive model is applied to predict the stress/strain curves of two-dimensional woven C/SiC composite at room and elevated temperatures. Good agreement was found between the experimental data generated and the results predicted by the continuum damage mechanics model. This demonstrates that the methods developed in this paper are effective. The numerical analysis of two-dimensional woven C/SiC laminate with a hole shows that the temperature effect will reduce stress concentration near this hole.