Numerical Prediction of Welding Distortion Considering Gravity Force on General Ship Grillage Structure by Elastic Finite Element Method Using Inherent Strain

Donghan Woo,Mitsuru Kitamura

doi:10.3390/jmse8060454

Donghan Woo, Mitsuru Kitamura

Open Access

https://doi.org/10.3390/jmse8060454

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Abstract

The accurate numerical prediction of welding deformation is important to improve the structural safety of ships and offshore structures in heavy industries. The precise reflection of the real working condition in the numerical prediction is an essential factor to improve its result. In the present study, the effect of the gravity force on numerical prediction of the optimal welding sequence of a general ship grillage structure was validated with the introduction of a new boundary condition in which the structure is placed over rails. Additionally, the direction of the gravity force of welded structures could be changed at the final assembly process according to the production plan. The effect of the gravitational orientation on the final welding displacements was also investigated herein. The elastic finite element method using the inherent strain, interface element, and multipoint constraint function was introduced to analyze the welding deformation. This study validated the influence of the gravity force on the numerical prediction of welding displacements in a general ship grillage structure.

Highlights

Welding is the most convenient method to build various steel structures such as ships and offshore structures
The representative reference value to discuss the effect of gravity on the numerical prediction of welding displacement of the general ship grillage structure is the z-axis distance average
The finite element method (FEM) approach is employed with the inherent strain, interface element, and multipoint constraint function (MPC)

Summary

Introduction

Welding is the most convenient method to build various steel structures such as ships and offshore structures. Welding deformation is inevitable due to its extremely high heat operation. The rapid change in temperature from heating to cooling along a welding line causes local shrinkages. Improvement in the accuracy of welding distortion prediction is one of the most essential factors to design a welding process efficiently. Many studies have been conducted to improve the numerical method for accurately predicting welding distortion. Previous studies have not considered the effect of the gravity force on the process of welding in the numerical simulation. In a structural analysis by the finite element method (FEM), the effect of the gravity force is not a negligible factor. The reflection of the gravity force in the numerical prediction of welding distortion is essential

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