A numerical study on interface crack growth under heat flux loading

A numerical framework for the coupled thermo-mechanical analysis of crack growth in structures loaded by an applied heat flux is outlined. Using a thermo-mechanical cohesive zone model (TM-CZM), load transfer behavior is coupled to heat conduction across an interface and the corresponding interface crack. Nonlinear effects occur due to the coupling between the mechanical and thermal problem introduced by the conductance–separation response between crack faces as well as through the temperature dependence of material constants of the CZM. The description of the load transfer behavior uses a traction–separation law with an internal residual property variable that characterizes the extent of damage caused by mechanical loading. The description of thermal transport includes a representation of the breakdown of interface conductance with increase in material separation. The current state of interface failure, the presence of gas entrapped in the crack, the radiative heat transfer across the crack and a contact conductance between crack faces determine the cohesive zone conductance. The TM-CZM is implemented into a finite element code and applied in the study of interface crack growth between an oxidation protection coating on a thermal protection material.