A local stress approach to predict the fatigue life of the U-notched PMMA plate at different temperatures

In this paper, the fatigue lives of U-notched polymethyl methacrylate (PMMA) plate at different temperatures are numerically investigated on the basis of local stress approach. First, a local stress approach for fatigue damage at the U-notch is presented based on the principle of equivalent damage life. Second, the strength and stiffness degeneration criterions during the fatigue process are established to take account of the nonlinear cumulative fatigue damage. Finally, the commercial software ABAQUS is employed to predict the fatigue S-N curves of the U-notched PMMA plate at various constant temperatures of −55 °C, 23 °C and 60 °C using a user-defined material (UMAT) subroutine. The numerical results of the fatigue life are in good agreements with the experimental data, which verify the effectiveness of the local stress approach.