A Comprehensive Structural Analysis Process for Failure Assessment in Aircraft Lap-Joint Mimics Using Intramodal Fusion of Eddy Current Data

Abstract

In the aerospace industry, nondestructive evaluation (NDE) techniques are commonly used for structural health monitoring, including finding manufacturing and service-induced discontinuities and defects such as corrosion and cracks. A comprehensive structural analysis process is presented for quantizing and evaluating characteristics of aircraft lap-joint mimics. The process investigated here consists of NDE data acquisition, defect detection and characterization involving material loss estimation, three-dimensional structural model generation, finite-element modeling to simulate fatigue damage and comparison with actual tensile fatigue-induced structural analysis data (mechanical loading). The structural analysis process is examined using five test panels consisting of stacked and riveted aluminum plates, configured as lap-joints, four of them with different corroded patches at different layers of the lap-joints and one painted pristine panel used as a reference. The test panels were subjected to three rounds of incremental and cyclical tensile fatiguing with the final round resulting in complete fatigue failure. Eddy current data was obtained from the test panels prior to each round of mechanical loading. Comparing the simulated fatigue loading and the mechanical loading results for identifying susceptible-to-failure areas on the test panels, this comprehensive structural analysis process found the correct location of failure areas at rates as high as 88.9%.