Modeling Cracks in Nonlinear Viscoelastic Media Subjected to Thermal Loading

Abstract

The study is concerned with the simulation of cracks in finitely deforming viscoelastic media. The main goal is to establish a computational methodology for crack propagation analyses in bulk material and interface debonding using an extended finite element method and cohesive zone modeling. First, a linear elastic plate with a single-edge crack and a linear viscoelastic plate with a double-edge crack are selected as benchmark problems. Upon verification of the extended finite element method and cohesive zone modeling results against those from the conventional crack propagation method and those from the literature, a nonlinear viscoelastic solid rocket motor subjected to various thermal loadings is analyzed for failure due to bore cracking or interface debonding. For a cooldown the stress distribution along the bond line is determined for the bore cracking mode and results are compared with those from the literature. For the cyclic temperature, the propagation of bore cracks is analyzed using an extended finite element method, and the propagation of initial debonding is studied using cohesive zone modeling. For both failure modes, crack propagation occurs only during the first cooldown. The relation between the crack growth and the initial crack size show parabolic behavior. Overall, it is concluded that the extended finite element method and cohesive zone modeling are suitable methods for crack propagation analysis in nonlinear viscoelastic media.