A Numerical Study of Non Uniform Multiple Site Cracks Emanating From a Two Dimensional Rivet Hole Array
Abstract A study was performed to assess the effect of multiple site damage (MSD), which has been observed in a number of aging aircraft, on the fatigue life of lap splice joints in fuselage structures. Numerical modeling was used to simulate various MSD occurrences in models similar to riveted aircraft structures (e.g. rows of 5/32″ diameter holes separated by a finite distance, for a T2024-T3 aluminum material) under simulated fatigue loading. Several geometric factors were examined, and their effect on MSD propagation investigated. Nonuniform MSD was also modeled, and all effects were compared on a global scale. Results indicate that a tighter array configuration allowed for a shorter fatigue life, as did the introduction of the nonuniform crack. However, the effect of the staggered offset was negligible in comparison to the effect of the rivet spacing and the location of the nonuniform crack. The size and initial location of the nonuniform crack had the greatest influence on the stress distribution and the fatigue life.