Prediction method for shear stability of composite hat-stringer stiffened panel

In this paper, the shear stability of a composite hat-stringer stiffened panel was studied by the means of both shear frame test and theoretical analysis. The test specimen is a typical flat composite stiffened panel composed of skin, five hat-shaped stringers, two Z-shaped transverse frames and reinforcement layers. Firstly, a method that can quantitatively capture the buckling load and buckling morphology was proposed. Then, considering the shear-loading fixture as an elastic system with hinged and bolted connections, a finite element model including both shear-loading fixture and specimen was established. The linear buckling analysis was carried out using the subspace method. The first-order buckling mode was in good agreement with the buckling morphology obtained from the test. Furthermore, the deformed configuration of the first buckling mode was multiplied by the mode scale factor, and then introduced into the model as the initial defect. Based on this model, the nonlinear buckling analysis was performed via arc length method. The analysis results were in good agreement with the test. The relative errors between the predicted buckling loads and the test results were 7.0 % and - 3.8 % from linear and nonlinear buckling analyses, respectively. Nonlinear buckling analysis has higher accuracy and tends to be conservative than linear buckling analysis.