Environment - Load Interaction Effects on Crack Growth

Abstract : The objective of this program was to systematically investigate chemical environment-load interaction effects on crack propagation. The program was focused by developing a set of design guidelines and criteria for a durability and damage tolerance control plan for landing gear. Current life prediction capability was assessed by comparison of prediction and test. A field survey was conducted to catalog the size, type, and locations of flaws in landing gear components. A crack growth prediction capability developed through analysis and test accounts for environment and load interaction effects. Materials studied are HP-9Ni-4Co-.30 and 300M steels, and 7075-T6 and 7049-T73 aluminums. A flight-by-flight test stress history was developed for a landing gear component, and crack growth predictions prepared. Subsequently, spectrum tests were performed. A Durability/Damage Tolerance Control Plan for landing gear is outlined.