Page 428 - Practical Design Ships and Floating Structures

Practical Design of Ships and Other Floating Structures 403
You-Sheng Wu, Wei-Cheng Cui and Guo-Jun Zhou (Eds)
8 2001 Elsevier Science Ltd. All rights reserved

NUMERICAL SIMULATION OF WELDING
DISTORTIONS IN LARGE STEEL STRUCTURES

Lars Fuglsang Andersen

Section of Maritime Engineering, Department of Mechanical Engineering
Technical University of Denmark
DK-2800 Kgs. Lyngby, Denmark

ABSTRACT
The scope of the present paper is to describe a technique which combines several methods to predict
welding distortions in large-scale industrial welding applications. The template is established in three
steps: First, a general model is made allowing the essential welding mechanics to be captured in fillet
welding. Subsequently, mesh grading techniques and dynamic meshing are used to enhance the
computational efficiency. Finally, substructuring, global shell models and dynamically meshed models
are combined in a template for further increase of the efficiency.

KEYWORDS
Large-scale welding applications, numerical welding simulation, dynamic meshing, templates.

1 INTRODUCTION

Geometrical distortions in the construction of steel structures are primarily caused by poor set-up of
assemblies and thermomechanical processing such as welding. The distortions accumulate throughout
the process chain and necessitate frequent compensation rework to maintain an acceptable distortion
level. The present paper regards the assessment of welding distortions for analysis of manufacturing-
related issues such as the effect of welding sequence. The paper provides mainly a summary of the
work presented in Andersen (2000, 2001a,b,c), which addresses the following tasks:

*Find all pertinent parameters and establish a basic model, which can account for the essential welding
mechanics in distortion prediction

Increase the computational efficiency of welding simulation by the use of optimised mesh grading
techniques and dynamic meshing

Develop a template that enables each weld line of an assembly to be modelled in detail one at a time
without neglecting the interaction between weld lines