Numerical analysis of cracked inelastic shells with large displacements ormixed mode loading

The trend in higher utilization of structural materials leads to a need for accurate numerical tools for reliable predictions of structural response. In some instances both material and geometrical nonlinearities are allowed for, typically in assessments of structural collapse of residual strength i n damaged conditions. Dynamically loaded structures are prone to fatigue cr acking; this has to be accounted for when computing nonlinear structural re sponse. The present study addresses the performance of cracked inelastic sh ells with out-of-plane displacement not negligible compared to shell thickn ess. This situation leads to membrane force effects in the shell. Hence, a cracked part of the shell will be subjected to a nonproportional history of bending moment and membrane force, and e.g. fracture mechanics parameters (J-integral) are affected. A Mindlin shell finite element based nonlinear p rogram is developed and utilized herein. The cracked parts are accounted fo r by means of inelastic line spring elements. These elements also account f or possible mode II deformations. (C) 1999 Elsevier Science Ltd. All rights reserved.