Effects of debond size on compressional behavior of single-stiffened composite panels

In order to research the effects of debond size on buckling and post-buckling behavior of single-stiffened composite panel under axial compression, four types of I-section stringer-stiffened composite panels containing different debond defects were investigated by test and numerical simulation. Strain measurement and ultrasonic scan were conducted to monitor the deformation and defect propagation in the process of buckling and post-buckling. Finite element analysis(FEA) models were established based on ABAQUS. LaRC03 criteria were introduced for the judgment of intralaminar damage and cohesive elements were used to simulate the damage of the interface between stringer and panel. Buckling wave was introduced by initial geometric imperfection. Processes of buckling and post-buckling of specimens were simulated by the FEA models. The simulated results are coordinated with the test results very well. Failure process and mechanism of debond propagation were analysis and discussed based on the tested and simulated results. The results indicate that debond size has significant effects on the buckling and post-buckling behavior of the specimens instead of the final failure mode. Loading capacity decreases rapidly with the increasing debond size, which needs to be focused on in the damage tolerance design of stiffened composite structures.