Study On Nonlinear Finite Element Analysis Method For Ultimate Strength With Collision Damage

Ship structure ultimate strength as a capacity to measure ship structure’ability to resist damage has been a important index to describe ultimate load bearing capacity of ship structure since Common Structural Rules published in 2006. Ship operation inevitably occur accident, collision accidents occupy most of the accidents, and the analysis of the ultimate strength of ship with collision damage can have an accurate judgment of the structural safety.In this paper the collision damage ship’s ultimate strength were studied with considering the influence of collision damaged region’s geometry changes and the change of mechanical properties on the ultimate strength. Then a nonlinear finite element analysis of the ultimate strength of the ship with collision damage is proposed.At first, this paper studies the most commonly used four kinds of ship structure ultimate strength calculation method and has certain understanding the principle and process of different methods.Then this paper determine to use nonlinear finite element method to calculate the ultimate strength, and use the Smith’s method in Common Structural Rules to compare.This paper establishes a finite element model example of a collision damaged ship, and make a program to extract collision damage region element’s material properties and nodes’ displacement.Then this paper establish the finite element model with collision damage.After that, this paper gets the turning angle-moment curve.After getting the collision damaged ship’s turning angle-moment curve with NFEM,this paper analyse the complete ship’s turing angle-moment curve with NFEM and turning angle-moment curve of collision damaged and complete ship with Smith’s method.At last,this paper conclude from results of different method and situation.The NFEM which use to calculate the ultimate strength of collision damaged ship is feasible and rational with the infulece of plastic deformation,buckling,fracture to ultimate strength. The method in this paper is more conservative and provide supplement to the analysis method to calculating the damaged ship’s ultimate strength.