Finite Element Method (FEM) for Bonded Repair Design

Fatigue-related effects are a significant cost driver for maintenance of military aircraft systems. Typically, inspection intervals are defined based on expected damage accumulation or crack initiation and propagation rates. When damage is found a decision must be made for whether the damaged component should be removed, repaired, or left alone until the next inspection. Repairing may include material removals and/or the installation of a patch which requires additional engineering decisions as to the extent of the removal or the type and size of patch to maintain structural integrity. The objective of this project is to provide a repeatable and reliable methodology for damage tolerance analysis of wing structures prior to and after the installation of repair patches. This objective will be met through a collaborative approach between ESRD and AP/ES; ESRD brings expertise in modeling of damage and best practices in application of the finite element method, and AP/ES brings expertise in damage tolerance analysis as applied to military aircraft structures. Ultimately this methodology will better equip the Bonded Repair Center of Excellence to more effectively evaluate damage, repair patches, and fatigue life.