Advanced Life Analysis Methods. Volume 2. Crack Growth Analysis Methods for Attachment Lugs

Abstract : Analysis procedures for the assessment of the damage tolerance of aircraft attachment lugs are developed and presented. Stress and fracture analyses are conducted for simple male straight shank lugs subjected to symmetric loading and tapered lugs subjected to symmetric and off-axis lodings. Solutions of stress distributions and stress intensity factors are obtained for various parameters. The parametric variations include lug outer-to-inner radius ratios corner and through-the-thickness cracks, crack lengths and aspect ratios, with and without interference-fit bushing and loads above and below yield of the lugs. Methods of varying degree of sophistication are considered in the development of stress intensity factor solutions for cracks in attachment lugs. For through-the-thickness crack problems, simple compounding method, two- dimensional cracked finite element method, and the weight function mthod are used. In the case of corner cracks, solutions are obtained using simple compounding method, weight function method and rigorous three-dimensional hybrid displacement cracked finite element method. The stress distributions and the stress intensity factors are consolidated into a crack growth analysis procedure including several crack growth models and spectrum retardation models to predict the fracture and crack growth behaviors in attachment lugs. Originator-furnished keywords include: Attachemnt Lugs, Cracking, Aircraft, Damage Tolerance, Analysis Methods, Straight Lugs, Tapered Lugs, Stresses, Stress Intensity Factors, Through-the-Thickness, Corner, Interference-Fit Bushing, Elasto-Plastic Analysis, Crack Growth Analysis.