# QUALITATIVE ANALYSIS OF THE DYNAMIC CRACK INITIATION AND PROPAGATION

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Abstract : Experimental results of the fast fracture of the crack is analyzed based on the extended energy balance equation in which the effect of micr ovoids generated at the tip of the crack is taken into account. We assume that the average radius r of microvoids grow in time as MATH, i.e., microvoids grow in the self-similar manner, statistically. It-s volume is defined as rD and the density distribution function nr of the microvoids is assumed to be MATH, where D and MATH are numbers. The surface roughness MATH defined as the average radius of microvoids is compared with the experiment. Thus we can estimate the numbers MATH and MATH as MATH and MATH, respectively. We have shown that the surface roughness which is called as -mirror- -mist- and -hackle- can be qualitatively analyzed from the energy balance equation if the parameters D and MATH are measured experimentally. Fur ther more, we have postulated the initiation condition of the dynamically loaded crack and extended it to the propagation stage. This postulate and it- s extension show the qualitative agreement with the experimental observations.

Author: ** M. Watanabe **

Source: https://hal.archives-ouvertes.fr/