Elastic-plastic crack growth simulation and residual strength prediction of thin plates with single and multiple cracks

This paper presents numerical simulations of elastic-plastic, Mode I crack growth in thin aluminum plates. Two series of tests are simulated, M(T) specimens, and specimens containing multiple co-planar cracks. Elastic-plastic, shell finite element analysis is used to predict the residual strength of the tested plates. The crack tip opening angle (CTOA) measured at a specific distance behind the crack tip is the fracture criterion to characterize stable crack growth under conditions of general yielding. For small M(T) specimens, the limit load is attained due to net section yielding after the plastic zone reaches a free edge. In contrast, the residual strength of large specimens is achieved after some amount of crack growth with the plastic zone well-confined by the elastic region. Results of predicted residual strength are comparable to experimental measurements. However, as the width of the panel increases, the relative difference between experimental measurements and numerical predictions increases. The same CTOA fracture criterion is used to simulate crack growth and link-up in the multiple crack specimens. Predicted link-up load and residual strength are in good agreement with experimental measurements. A loss of residual strength due to the presence of multiple small cracks is observed.