Current Practice on Estimating Crack Growth Damage Accumulation with Specific Application to Structural Safety Durability and Reliability

This report provides a brief summary of current practice on predicting crack growth damage accumulation with specific applications to current USAF policies on Safety and Durability. Analytical procedures are required to determine safe crack growth-life intervals and to estimate economic limits of crack growth. Reliability and risk analyses are discussed to illustrate their impact on structural decisions. The life prediction methodology will be examined to illustrate the major effects of the structural parameters (geometry), the material parameters (basic crack growth rate) and loading (usage patterns). Examples are cited to give indication of confidence in making life predictions. A summary of procedures for estimating service loads and chemical-thermal environments is included as they relate to simulating usage effects in the laboratory.