An anisotropic elastoplastic damage constitutive model for 3D needled C/C-SiC composites

This paper established a combined elastoplastic damage model to analyze the nonlinear mechanical behavior of 3D needled C/C-SiC composites. Inelastic deformation and stiffness degradation of the composite were characterized by the plasticity and damage theories. An innovative plastic potential function containing variable parameters was proposed to consider particularly the anisotropy of plastic deformation in each material direction. Based on the Weibull statistical distribution of the material strength, an exponential damage state function was established to characterize stiffness degradation for the composite in each material direction. Parameters of this constitutive model were determined from experiments data. It can be found that the nonlinear stress-strain curves for the composite under off-axis tensile and shear loadings can be accurately described by the model. The yield and damage surfaces of the composite were also studied. Finally, the constitutive model was validated by analyzing the mechanical behavior of a composite plate containing a center-hole subjected to tensile load.