Composite repairs to rib stiffened panels

There are several methods available for obtaining a first estimate for the design of composite repairs to cracks in thin metallic skins. One approach uses analytical formulae, which build on an analogy with the problem of a bonded symmetric lap joint (Rose LRF. An application of the inclusion analogy for bonded reinforcements. Int J Solid Struct 1981;17:827–838; Fredell RS. Damage tolerant repair techniques for pressurized aircraft fuselages. PhD Thesis, Delft University of Technology, June 1994; Baker AA, Jones R. Bonded repair of aircraft structures. Dordrecht: Martinus Nijhoff, 1988). The present paper extends this methodology to include the bonded repair to rib stiffened wing skins. To this end the present paper presents the results of a series of 3-D finite element analysis of various composite repair configurations. This study reveals that, after repair, the stress intensity factors exhibits an asymptotic behaviour as the crack length increases and that this stress intensity factor is a weak function of the stiffener spacing.