Fatigue life analysis of a composite materials structure using allowable strain criteria

In the current research, a method for estimation of the durability of a structure based on an integrated calculation of static and fatigue strength according to the criterion of allowable strain is presented. The proposed technique is demonstrated for the upper stringer panel of the wing design. In the course of calculations, several combinations of design service objectives, levels of allowable strains, and levels of cyclic stresses were considered. As a result, the relative values of stiffness degradation and the required safety ratios of static strength were obtained.