Experimental Study and Simple Failure Analysis of Stitched J-Stiffened Composite Shear Panels

Two fuselage type, stitched composite shear panels with J-shape stiffeners manufactured through the process of Resin Transfer Molding technique were tested. Through the diagonal tension tests, it was found that failure of each panel occurred at approximately 3.5 times its initial buckling load, indicating significant diagonal tension strength. Neither of the panels failed by stiffener “pop-off,” showing that the stitching helps to inhibit this failure mode. No other damage or delamination of the panel was visible as well. The newly developed generalized Yeh-Stratton (Y-S) failure criterion was used to evaluate the failure of these composite panels. Compared with several other failure criteria, the calculated failure loads are quite close to experimental results and all are conservative. The Y-S criterion is the most conservative for this case.