DAMAGE CONSTITUTIVE MODEL FOR THERMAL SHOCKED-CERAMIC MATRIX COMPOSITE

The ceramic-matrix composite (CMC) structure is inevitably subjected to cyclic thermal shocks in service, which induces the thermo-mechanical damage. Investigation of the damage constitutive model of the thermal shocked-CMC is of significance in the design and performance evaluation of such composites in aeronautical industry. In the present work, monotonic tensile damage tests were conducted for the thermal shocked-CMC. It is found that the degradation of elastic modulus for the thermal shocked-composites are directly related to the applied strain. Based on the framework of continuum damage mechanic, a nonlinear damage evolution model for the thermal shocked-CMC was proposed under plane stress assumption. The identification of the damage parameters involved in this model requires one off-axis (45^\circ), and two on-axis (parallel to tow directions) uniaxial tensile tests. Finally, the inelastic strain caused by matrix damage is described by classical plastic theory. The proposed strain damage macroscopic model can describe the damage evolution of CMC under thermo-mechanical loading, and also compensate the deficiency of the theoretical and experimental research for the damage evolution model of damaged-CMC under mechanical loading.