Repairs to pressurized fuselages have been done traditionally by using mechanical doublers. While bonding of metal structures and bonded repair techniques have existed for about 50 years now, bonded repairs have not gained as much acceptance as the mechanical doubler repairs. This is mainly due to the disappointing early experience with bonding and the lack of widespread understanding of bonded repairs among technicians. This provides the motivation for the development of effective analysis techniques that can be implemented on low end workstations. In this investigation, the mechanical doubler repairs have been compared with bonded repairs in the repair of cracks in the fuselage skin. To analyze the effect of global loading (viz. pressure loading in the fuselage shell), on the essentially local feature of repair, a hierarchical approach has been used. This allows the fuselage to be modeled with increasing detail over smaller regions. Using this approach the stress redistribution caused by mechanical doubler repair is compared with that caused by composite patch repairs. The residual strength and fatigue life of fuselages with composite patch repairs have been compared with those of the un-repaired case. The stress intensity factors have been evaluated by considering the adhesive as elastic material and as an elastic perfectly plastic material. Parametric studies of composite repairs are conducted using this methodology.
|Number of pages||28|
|Journal||American Society of Mechanical Engineers, Aerospace Division (Publication) AD|
|State||Published - 1995|
|Event||Proceedings of the 1995 ASME International Mechanical Engineering Congress and Exposition - San Francisco, CA, USA|
Duration: Nov 12 1995 → Nov 17 1995