Author Description

In this research, the fatigue analysis of the improved pad design of laser welded stringers for aircraft is addressed. The research starts with the benefits of the pad design stringer given through the analyses based on the regular T-plate structure and the pad design was optimized by stress state analyses on the potential crack plane using the finite element method. The solutions of stress intensity factor for a single edge crack originating from the weld toe on the stringer were derived using both the finite element method and the weight function method. The two methods gave the stress intensity factor solutions for the range of relative crack depths ('a/t ') between 0.05 and 0.8 under pure tension, three point bending and four point bending. The derived weight function solutions were obtained from the assumed approximated general weight function and two reference stress intensity factors, and were verified against the finite element method solutions. The derived weight function solutions were utilized to predict the fatigue crack propagation behavior under remote tension and bending for a single edge crack originating from the weld toe of a pad design stringer. (Abstract shortened by UMI.).