Thermal shock resistance enhancement of auxetic honeycomb layer considering multi-cracking and temperature-dependent material properties

This paper assesses the thermal shock behaviors of the auxetic honeycomb layer (HL) through consideration of crack propagation and new crack initiation. All material properties are temperature-dependent. To calculate the thermal stress field with no crack, the finite difference approach is used. On this basis, a theoretical model for thermal stress intensity factor and thermal stress between cracks is developed. The model combines the equivalent fracture toughness and equivalent tensile fracture strength as the failure criteria. The critical temperature for crack propagation and new crack initiation in the HL is determined. The results reveal that the thermal shock resistance (TSR) of the HL is overestimated if the temperature-dependent material properties (TDMPs) are not taken into account. Multiple cracking can dramatically improve the TSR of the HL. Compared to the non-auxetic HL, the TSR of the auxetic HL is significantly enhanced. Furthermore, the HL with lower relative density generally possesses higher TSR, and the corresponding physical mechanisms are revealed.