Head, Fracture Mechanics Laboratory, Structural Mechanics Division, National Aerospace Laboratory, Tokyo,
Pages: 18 Published: Jan 1995
The improvement of damage tolerant testing methods is strongly suggested today, in order to evaluate the structural integrity of aging aircraft against time-dependent degradation such as multi-site damage or multi-element damage resulting from the interaction of corrosion and fatigue. From this point of view, the following suggestions were made based on the case study of a Japan Airlines accident which occurred in 1985 and a related study on fastener joints. In that study, the effects of squeezing stress of the fastener and number of flaws on the crack propagation life were examined.
Thus, for damage tolerant testing, the author proposes that; 1. The total width of the area of artificially damaged fastener joint should be wider than the critical crack length of each structural component. 2. The length and the number of these flaws are recommended to be introduced in accordance with two parameter Weibull distribution function. 3. The squeezing force after these flaws being introduced should be controlled in order to simulate the corrosion degraded structures, since the squeezing condition is the major factor that determines the fatigue life of the joint structures.
aging aircraft, damage tolerant evaluation, multi-site damage, case study, fastener joint, load transmission, crack distribution
Paper ID: STP14616S