Abstract: The huge torque, beard by the stiffened panel and caused by the landing impact on the wing box section,is an important condition for the design of wing panels. To accurately predict the shear post-buckling capacity of the stiffened panel, the uniform mode defect displacement of liner bucking analysis is introduced as a disturbance to the post-buckling analysis by using the MSC.NASTRAN MRIKS arc-length method. Considering the geometric and material non-linearity, the post-buckling failure process of the shear specimen of the integrally stiffened panel is simulated and the carrying capability is predicted. Based on the test results, a comparative analysis is carried out, and the results indicate that the initial buckling of the stiffened panel occurs on the skin, and sufficient relative stiffness of the stringer produces the buckling node in the connecting line of the stringer and skin. As the load increases, the stiffened panel collapses, showing consistency with the test phenomenon. Compared with the results of the test, the error of the initial buckling load simulated with Finite Element Analysis (FEA) is about 1.25%, and the error of the failure load predicted with FEA is about 2.4%. So, the nonlinear post-bucking calculation based on the MSC.NASTRAN arc-length method with introduced defect can be used to accurately predict the load bearing capacity of the stiffened panel. The research provides an analytical method for the shear test and strength design of the stiffened panel.

Key words: stiffened panel, shear, post-buckling, load bearing capacity, finite element analysis