Design and experimental verification of composite stiffened panel under combined compression-shear loads

Abstract As an important part of the aircraft, the panel structure accounts for a large proportion of the building block verification system. The real stress state of the aircraft panel is usually not a uniaxial compression or shear, but a combined loading condition in service. In the past, box structure was usually tested for structure selection in the aircraft’s preliminary design phase, which was limited by immature panel test methods and equipment. At present, a general panel test system considering the actual load form and boundary conditions was independently developed by the Aircraft Strength Research Institute of China. A large-scale composite stiffened panel was designed and tested on this test system in this paper. The whole process of the test was monitored by digital image correlation technology and strain gauge measurement. The test process and results were detailed and analyzed. Experimental results show that the failure modes of stiffened panels under combined compression-shear loads include mainly three forms. The first is in the upper part of the panel, which shows a typical shear failure mode and tears along the shear loading direction of the specimen. The second is the fracture of the reinforced piece in the bottom right-hand corner of the specimen due to compression loads. The third form is the large-scale cracking at the junction of the reinforced piece and skin, which may be related to the coupling effect of combined loading.