Bonded repair patches

Abstract

The growing number of ageing aircraft around the world, both military and civil, has led to an increasing demand for safe, damage tolerant, and cost-effective repairs to solve the inherent fatigue damage and corrosion damage problems. Adhesive bonding of Glare repair patches can provide such a solution. While Glare can be used for conventional repair methods like riveting and bolting, bonded patches provide a uniform and efficient load transfer into the patch and reduce the risk of high stress concentrations caused by mechanically fastened repairs. The advantage of Glare repair patches compared to other patch materials lies in the small mismatch in the coefficient of thermal expansion (CTE) with the aluminium skin, the excellent fatigue properties, the high strength, the moderate extensional stiffness and high bending stiffness. This makes Glare a promising candidate for safe and cost-effective bonded repairs for thin skin structures, not only for ageing aircraft, but also for repair of in-service damage of relatively new aircraft (high request of repair performance). Extensive research has been performed in a joint research programme of the Faculty of Aerospace Engineering of Delft University of Technology and the Center for Aircraft Structural Life Extension (CAStLE) of the United States Air Force Academy. An overview of this research will be presented here.