1 Finite Element Analysis for Advanced Repair Solutions: A Stress Analysis Study of Fastened and Bonded Fuselage Skin Repairs

The advanced repair solutions investigated within this research programme, both mechanically fastened and adhesively bonded repairs, could extend their in-service life beyond the Design Service Goal (DSG) of the aircraft in which they are embodied. Beside the test activity (discussed in previous publications), calculation methods (based on Finite Element models) were developed to improve current methods to predict the fatigue behavior of repairs and to optimize the design principles of the advanced repair solutions. The use of internal doubler to reduce the secondary bending, different fastener type or additional fastener row, as well as, the influence of fastener installation (Hi-Lok ® interference fit) are reported. Other advanced repair solutions, such as bonded repair or the use of glare® doubler to repair aluminum skin, were also investigated and reported in this work. In this paper different kind of Finite Element (FE) models used to simulate the tests are reported. The stresses resulted from the FE analysis were compared with the ones measured experimentally by strain gauges. Nomenclature μs = Static coefficient of friction μk = Kinematic coefficient of friction r = Fastener radius rdepth = Fastener countersunk dept