Materials used in a naval collision calculation with finite element software

Abstract

Collisions and groundings have a significant contribution to structural damages occurring to ships. For collision calculation are used non-linear relations between strains and deformations, considering a significant difference between the initial shape and final deformed shape of the structure, and the mechanical equilibrium equations are written on the deformed shape of the structure. Using a mechanical test to a material sample will result the connection between the engineering strain and engineering deformation. During numerical simulation, we are using the real mechanical characteristic curve, which represents the reliance between real strains and real deformations, those being calculated from the distorted material sample. For calculation, we are using Johnson – Cook plasticity model, frequently used by other authors as well during collision calculation. There is included new information, also tabular calculations using specific formulas, resulted during carried out studies, to establish the model parameters considering the measured data or using information from another material model (exponential law). Considering the materials used within ANSYS software and calculus processor LS-DYNA, are presented types of materials useful for collision calculation, describing the elasticity, plasticity and yielding. Following, it is used a procedure for dynamic explicit calculus because it is suitable for solving of nonlinear systems. During simulation with finite element of the collision, there are no strains and deformations concentrations and it is necessary to generate an artificial curve, which leads to same results, as in reality and as well finite element analysis.