Combined strain rate, mesh size and calibration test influence on structural failure: Miniature ship grounding test

Abstract

This paper investigates the influence of the strain rate and element size on the fracture of steel plates presented in marine structures undergoing grounding when modeled by the finite element method. Three different experimental tests (tensile, tearing and perforation tests), performed at different velocities, are used in the study. These tests are conceived to cover diverse rupture modes related mainly to crack initiation and propagation. Plastic strain- and stress state-based failure criteria were calibrated from these experiments. Sensitivity to strain rate and mesh size were also evaluated. A ship grounding event was reproduced experimentally in 1:100 reduced scale. This experiment was FE modeled to evaluate the performance of the aforementioned failure criteria. The results verified the significant influence of the strain rate and stress state on the failure strain. In addition, it is shown that the sole use of tensile tests is not enough to properly characterize the material failure observed in the structural collapse mode of the miniature ship bottom structure. This collapse is shown to be a combination of stretching and tearing of structural members.