On the Experimental Evaluation of the Mode II Stress Intensity Factor by Grown Grain Copper Foil Gauge under the Action of Frictional Force on Crack Surfaces.

Abstract

The relation between the strain sensitivity and the grain size of grown grain copper foil gauge which has preferred orientation to slip is examined. We Adopted this gauge to evaluate the mode II stress intensity factor KII of the through thickness crack in a plate subjected to cyclic torsion. The KII values obtained are lowered compared to the calculated value by the action of frictional force on crack surfaces. Using the KII obtained and KI for plane bending, it becomes clear that the threshold condition of crack propagation under the mixed mode of the combination of bending and torsion is governed by the strain energy density criterion.