Influence of MSD crack pattern on the residual strength of flat stiffened sheets

A parameter study of the residual strength for a multiple site damaged (MSD ) stiffened sheet is presented. The analysis Is based on an elastic-plastic fracture analysis using the yield-strip model for interaction between a le ad crack and the smaller MSD cracks. Two crack growth criteria, one with a pronounced crack growth resistance and one with no crack growth resistance and five different MSD crack patterns, are analysed for different sizes of the lead crack and the smaller MSD cracks. The analysis indicates that the residual strength reduction depends on all these parameters and that MSD ma y totally erode the crack arrest capability of a tear strap. Another import ant outcome is that for certain combinations also very small MSD cracks may induce a significant residual strength reduction.