关键词: 整体加筋板, 应力强度因子, 剩余强度, 破损安全, 胶接, 断裂控制

Abstract: The fail safety of large integrally stiffened panel is investigated based on the linear elastic fracture mechanics and finite element analysis. A nine-stringer integral aluminum alloy panel is analyzed for a skin crack under central broken stringer propagating toward the adjacent stringers. Comparison is made between the stress intensity and residual strength results of the panel and those of a rivet stiffened panel with the same configurations. The fail safe capability of the integral panel is not satisfactory when the crack is beyond two bay length, due to the crack growth and breaking on stringer web. To improve the fail safety of the integral stringer panel, the adhesively bonded strap is chosen as crack stopper. The material of the strap is either titanium alloy or fiber-reinforced unidirectional composite laminate. The method to simulate crack propagation and local strap debonding is designed and the computer code is made for the iterative use of NASTRAN package. The simulation shows that the bonding straps are very effective in reducing the stress intensity of integral panel cracks and thereby improve the fail safety of the panel remarkably.

Key words: integrally stiffened panel, stress intensity factor, residual strength, fail safety, adhesive bonding, fracture control