Linkup Strength of 2024-T3 Bolted Lap Joint Panels with Multiple Site Damage

A modified linkup model has been developed for determining the residual strength of 2024-T3 aluminum panels with multiple-site damage. This model was developed by semi-empirical analysis of test data from flat unstiffened open-hole panels. The model was later validated with test data from 36 open-hole stiffened panels. During the investigation, 36 bolted lap joint panels with different crack configurations were tested to further validate the previously developed modified linkup model. Stress intensity factors for the modified linkup model for the different crack configurations were determined from finite element analysis with the FRANC2D/L code. The residual strengths predicted by the modified linkup model correlate well with the test data, as was the case with the earlier studies of the stiffened panels. The results for the bolted lap joint panels show a sudden reduction in the residual strength at the early stages of multiple-site damage followed by a gradual linear decrease with increasing multiple-site damage crack size. The results also demonstrate that a stress-intensity-factor-based solution can be formulated with empirical analysis of test data from a simple configuration and then used to analyze more complex configurations.