a method for engineering application is put forward; and it not only reflects real mechanical course
but also obtains and measures its value readily and objectively. The definition of relative damage is brought out. The degree of damage expansion and relative damage of different parts when the damage material under blasting action could be expressed with it
and the determination of damage variable which measures the degree of loading is easier. At the same time
based on crack expansion
a computation method of damage cumulation is suggested.