Computational methods for the prediction of out-of-plane deformation in thin plate welded structures

Abstract

Introduction: Welded structures are subjected to highly localized heat distributions at the fused region. This gives rise to non-uniform heating / expansion and cooling / contraction of the weld and surrounding base material, which consequently give rise to welding residual stresses and deformation. Means of mitigation welding distortions are possible, however a better strategy to control distortion would be to predict the final deformation for different welding configurations and then select the best procedure to achieve the required tolerance in distortion. Various computational strategies are possible ranging from complex multi-physics analyses to simple analytical models. The approach adopted in this study, uncouples the thermal, elasto-plastic and structural effects leading to distortion. The most simplistic and computationally efficient model (CEM) makes use of simple algorithms, named 'Mismatched Thermal Strain' (MTS) and 'Contraction Thermal Strain' (TCS) that link the thermal welding strains to the elasto-plastic and structural response of the welded assembly, via a single static load step analysis. A more computational intensive models (CIM) that simulates the full transient thermal and elastoplastic structural response in an uncoupled fashion, is also presented. The computational models and results generated in this study have been supported at all stages by welding tests of a realistic nature. The thermal and distortion transients together with the final out-of-plane deformation were recorded during and after welding. In this paper a general review of the computational strategy and some experimental test results are discussed in context of butt and fillet welding of 0.5m square plates and of more realistic dimensions at4m x 1.5m plates.