Peridynamic simulation of fracture mechanical behaviour of granite specimen under real-time temperature and post-temperature treatments

This study developed a fully coupled thermo-mechanical model within the framework of ordinary state-based peridynamics to investigate the thermal-mechanical properties and fracture characteristics of granite materials under real-time temperature (RT) and post-temperature (PT) treatments. Moreover, a modified multi-layer computational method was proposed to eliminate the effect of thermal gradient-induced cracks. In this method, the size of the thermal layer was set to be larger than that of the tested sample, with the additional area used to withstand the thermal shock. During the loading process, the thermal damage information was transplanted to the corresponding position of the mechanical layer with the data of the additional area cut off. It was verified that thermal cycling cracks and thermal gradient-induced cracks could be modelled and distinguished, and the stress-strain and cracking behaviours of both RT and PT samples could be properly simulated using the proposed method. First, two benchmark examples involving heat conduction in a square plate and uniaxial compression of a granite specimen were simulated to investigate the numerical convergence and calibrate the simulation parameters, respectively. Then, two numerical examples were used to investigate and compare the stress-strain behaviours, cracking patterns, and temperature evolutions of the RT and PT samples. A systematic comparison with the experimental results makes it possible to discuss and summarise the failure mechanism of granite specimens subjected to PT and RT tests.