Damage mechanism of coal under impact loads

Stress-strain relations of coal were derived under various rates of strain by means of impact and static experi- ment. According to experimental results and the dynamic features of coal,the constitutive equations of coal strain-rate effect and damage characteristics were established by improving Z-W-T constitutive models. Embedding the established equation into finite element program and researching coal’ s damage mechanism under impact loading of different peaks,the study reveals that the layered interval splitting structure appears when coal is under impact loading,whose splitting structure has mainly two kinds of forms. One is “ zooming ” damage led by tension shear, the other is “stepped” damage led by compression-tension shear damage accumulation.