Development of a Hydraulic Spring-Type, High-Speed Impact Fatigue Testing Machine and the Experimental Results

Abstract

In order to examine the threshold condition for the propagation of a through crack under the mixed mode, plane bending tests, cyclic torsion tests, and their various combinations are carried out under the condition of the stress ratio R=-1 using annealed center-cracked specimens made of carbon steel. Taking account of the frictional stress acting on the crack surface under cyclic torsion, and adopting the strain-energy density criterion, the threshold stress of crack propagation under the combination of plane bending and cyclic torsion can be deduced from the individual test results of plane bending and cyclic torsion.