Improved damage-tolerance analysis methodology

A computerized damage tolerance analysis methodology, which can be reliably used to predict the fatigue crack growth behavior and lives of various types of cracks contained in metallic structures, subjected to complex spectrum loadings, has been developed This analysis method was developed primarily for the performance of the damage-tolerance analysis in the detail design stage of any aircraft system A state of the art load interaction model, which accounts for both retardation and acceleration, as well as their coupling effect to crack growth behavior, has been incorporated in this analysis methodology in order to predict fatigue crack lives more ac curately A two dimensional growth option is provided to account for the shape change effect of part through cracks (PTC) such as surface flaws and corner cracks at holes. A linear approximation technique is used as the damage accumulation scheme for saving computation costs This methodology has been implemented into a new computer code, the CRKGRO program A series of crack growth data correlation studies has been conducted using CRKGRO Results demonstrated that this damage tolerance analysis methodology provides reliable predictions on fatigue crack growth lives for cracked specimens subjected to spectrum loadings of various classes of aircraft