Structural Integrity of Aging Aircraft

The stress analysis and fatigue life prediction of the bonded repaired damaged zone of the aircraft structure is a challenging problem for designers. The lack of accurate life prediction methodologies limit the utilization of composite materials to repair the damaged structure. It is proposed to develop analytically and experimentally validated computer program modules for stress analysis and fatigue life prediction of bonded composite patch repaired metallic structures. The accuracy of these solution approaches would be compared among themselves, with available commercial FE packages, and also with a novel variational analysis developed by AdTech for three-dimensional analysis of bonded joints and repairs. The analysis methodologies that most accurately analyze the bonded repair situations will be integrated with the existing repair analysis computer programs as per the Air Force requirements. This effort would result in user-friendly, validated computational tools for analyzing bonded composite repairs. The proposed effort will aim at fulfilling the technological gap in the utilization of composite materials for repairing the damaged and/or weakened primary and secondary structural components of the aging commercial and military aircraft fleets, and would be a giant step in extending the service life of the aging aircraft fleet.