Fatigue Analysis of Multiple Site Damage in Lap Joint Specimens

This paper describes research to determine the influence of multiple-site damage on the fatigue life of lap joint specimens. Multiple-site damage is an important concern in aging aircraft and deals with determining failure conditions for multiple crack configurations. The goal of this paper is to determine the fatigue life for a mechanically fastened joint with multiple fatigue cracks located along one row of rivet holes. A predictive model for the fatigue life is evaluated with the results of several precracked specimens tested to failure under constant amplitude loading. Predictions for the growth and coalescence of individual cracks in specimens with various initial crack configurations and applied stress levels agree well with the experimental results.