An experimental and numerical analysis of residual strength of butt-joints panels with multiple site damage

Abstract The paper presents a combined experimental and computational study of the residual strength of a butt-joint panel with multiple site damage (MSD). The computational model uses a special strip-yield model adapted to MSD, which is implemented into a geometrically nonlinear finite element model. Crack initiation is modelled by a critical crack opening displacement and tearing by a constant crack opening angle criterion. Centre cracked tension tests were first performed to determine the basic fracture parameters. These fracture parameters were then used in the analysis of butt-joint panels with a large lead crack and smaller MSD cracks inserted along the upper row. The simultaneous propagation of multiple cracks in the tests was monitored continuously by aid of a specially developed image analysis technique. Loads for crack initiation, propagation and subsequent crack link-up and panel failure were computed and compared with test results. The geometrical nonlinear effects and the sensitivity to variations in fracture parameters were quantified. An excellent overall agreement was found for the most refined models.