Thermal cracking simulation of functionally graded materials using the combined finite–discrete element method
The functionally graded materials (FGMs), characterized by spatially varying material properties, have been used in a wide range of engineering applications (i.e., aerospace, nuclear reactor and microelectronics) in high temperature and high-temperature gradient environments. The prediction of crack behavior under severe temperature conditions is essential for the safety and long-term service life of such critical components. In this paper, a novel thermal–mechanical coupling model for FGMs is proposed, which consists of a thermal part for the temperature field computation and the combined finite–discrete element method part for the crack evolution modeling. The spatially dependent material characteristics of the FGMs are captured in this model, together with typical property variation functions (quadratic, exponential and trigonometric). The accuracy and robustness of the proposed coupled TM model are validated by numerical tests. Then, this model is applied to investigate the thermal cracking process in FGMs under different kinds of thermal loads. The influence of the crack interaction on crack growth pattern is also discussed. The results show that the proposed method is useful to the fracture mechanics analysis and design of the FGMs structures.
Keywords: Functionally graded materials (FGMs), Thermal–mechanical coupling problem, Thermal cracking, Crack interaction, Combined finite–discrete element method (FDEM),