Application of nonlinear continuum damage model in fatigue modeling of different stress ratio tests

Non-linear cumulative fatigue damage model based on continuum damage mechanics (CDM) is considered to model the maximum stress - fatigue life for different stress ratio. The used model is dependent on the maximum stress, ultimate strength, and the mean stress. A simple relation is obtained to give the fatigue life of the element under cyclic loadings. Its ability to describe all the main features of fatigue damage and the ease of its practical use for engineers, are discussed. The material constants of the used model for 7075-T6 alloy are obtained based on two different stress ratios. The CDM model is applied for different stress ratio and S-N curves are obtained numerically.