Crack growth response of IMI 834 under variable amplitude loading

摘要

The paper addresses the application of constant load amplitude fatigue crack growth data in the prediction of crack development at stress concentrations subjected to variable amplitude loading. The variable amplitude cycles were applied in repeated blocks. Several loading forms were evaluated in which each block included a single major cycle and either 5, 20 or 100 minor cycles with amplitudes between 30 and 70/100 that for the major cycle. The relative position of the minor cycle is also varied. The basic behaviour of the IMI 834 alloy was measured on comer crack specimens at R values of 0, 0.3, 0.5 and 0.7.