Crack damage evolution in coal at elevated temperatures

This work studies the behaviour of coal samples at various thermal environments from sub-zero temperatures of -100 to 300 °C by monitoring their fracture speed, ultimate strength, and crack damage evolution mode. High-speed recordings captured at 140,000 frames per second identified three different fracture evolution modes as a function of the applied ambient temperature. As the temperature increases, the fracture behaviour was observed to be through intact rock bridges resulting in reduced crack speeds and smaller fragments. Interestingly, at sub-zero temperatures, a different failure pattern was observed through the formation of a single fracture plane resulting in larger fragments with sharper edges.