The experiments of strength, destruction process and destruction type for samples of hard coal, soft coal and medium-hard coal are carried out, and the destructive characteristics of impact coal-mass,especially the law of volume-expanding in whole process from the load to be set on to destruction of coal-mass, are analyzed.

Adopting the original blade of the impact cutter,by use of Pro/Engineer Wildfire and Autocad 2004,a more reasonable new blade is designed.

Based on the characteristics in the strength of coal seam under the action of the ground pressure, the impact coal cutting is achieved in the coal winning technique by using the impact cutting tool to impact, split and cut the coal on the coal wall.

Based on observation results of the micro-topography of impact trend coal fracture surface with SEM method,the characteristics of defect such as pores,cracks and crack propagation in fracture surface of coal samples were analyzed,and the crack growth route and micro-fracture mechanisms of the hard brittle coal were studied.

Study on speciality of anti-circular cone impact for Kevlar composites;