HIGH-CYCLE FATIGUE BEHAVIOR OF SPHEROIDAL GRAPHITE CAST-IRON

An expression for the cumulative failure probability of a structure is proposed for cyclic loading conditions. This expression is dependent on an initial flaw distribution and a microcrack propagation law. Two sets of experiments were carried out on specimens made of spheroidal g raphite cast iron. These specimens are tested under cyclic tension wit h two different load ratios. The initial flaw distribution is experime ntally identified from microscopic observations. The crack propagation law parameters are identified from experimental results obtained with a load ratio R = 0.1. The expression for the failure probability is t hen used to predict experimental data obtained with a load ratio R = - 1.