A Simplified Fatigue Design Methodology for Composite Structures

摘要

A simplified methodology is presented to predict fatigue life and residual strength of composite structures. To avoid excessive amount of tests that are required for model characterization, the model parameters(strength degradation parameter, fatigue shape parameter) are assumed as function of fatigue life. S-N curve is used to extract fatigue life that is required to characterize the stress levels comprising a randomly-ordered load spectrum. And different stress ratios are handled with Goodman correction approach(fatigue envelope). It is assumed that the residual strength is a monotonically decreasing function of the number of loading cycles and applied fatigue stress ratio. And the residual strength distribution after an arbitrary load cycles is represented by two parameter Weibull functions.