Rapid assessment of ship raking grounding on elliptic paraboloid shaped rock

Abstract

ABSTRACT The proposed paper presents a simplified analytical method for predicting the resistance of ship bottom structure subjected to grounding over a sharp rock idealised as an elliptic paraboloid. During grounding, sharp rock may lead to earlier penetration and serious consequences, such as compartment flooding, oil leakage. Therefore, it is of great importance to assess the response of a ship’s bottom structure rapidly and accurately during grounding scenarios. Two new theoretical models, based on plastic limit analysis, are derived with the objective to capture the main failure modes of bottom plating and floors. Proposed formulations are then confronted to Ls-Dyna numerical simulations and other formulas from the literature, considering different rocks, penetrations, and friction coefficients. A good agreement between analytical and numerical results is found and it is concluded the proposed model can be advantageously used to assess at the pre-design stage the crashworthiness of a grounded ship bottom.