عنوان مقاله [English]
Fatigue life and crack growth retardation due to periodic tensile overloads which are superposed on constant amplitude cycles have been investigated. In the numerical analysis the Forman/Mettu equation with the generalized Willenborg model is used. Analyses and experiments are performed on C(T) specimens made of 7075 aluminium. In the experiments and analyses the periodicity of overloads was remained constant and the effect of overload ratio on the fatigue life has been researched. Results of the experiments and analyses reveal that the N/NCA versus OLR curve has a maximum which indicates that there are greater retardation effects in intermediate OLR values. Also the numerical and experimental results show that in occurrence ratio of 1/50 the overload ratio of 1.5 lead to the maximum interaction.