Study on mechanical properties and energy evolution law of coal samples with different impact tendency

In order to study the mechanical properties and energy evolution law of coal samples with different impact tendency under cyclic load, the systematic analysis of coal samples with strong, weak and non-impact tendency is carried out, and the release rate and calculation method of elastic energy are put forward.The law, strain change law, dissipation energy and elastic energy transformation of stress-strain curve under cyclic load of coal samples with different impact tendency are obtained.The results show that the stress-strain curve of non-impact coal sample has the law of sparse dense, the stress-strain curve of weak impact coal sample has the law of sparse dense, and the stress-strain curve of strong impact coal sample has the law of dense.With the increase of impact tendency, the peak unloading strain and the average unloading strain decrease gradually.The average peak strain of strong, weak and non-impact coal samples increases first and then decreases.With the increase of the number of cycles, the dissipation energy decreases firstly and then increases, and the elastic energy increases more and more.The elastic energy index increases firstly and then decreases, and fluctuates locally.With the increase of impact tendency, the less the consumption of plastic properties in the process of cyclic loading, the more elastic energy stored, and the more energy converted during failure.