Parameter Optimization of Thermal Shrinkage Technique for Simple Numerical Simulation of Welding Angular Distortion

The thermal shrinkage technique, which uses shrinkage strain to determine weld distortion, shows promise as a simple simulation for predicting the weld distortion of large welded structures. To date, there has not been adequate research on how to set input data based on welding conditions. In this work, we perform a parametric study using thermal shrinkage technique in which we vary the input data to investigate the optimum setting method. To compare angular distortion obtained by the thermal shrinkage technique, Metal active gas welding was conducted under five welding conditions and thermal elastic-plastic analysis was conducted under the same welding condition. Under all five conditions, the angular distortion obtained by the thermal shrinkage technique accurately reproduced that obtained by experiments and by thermal elastic-plastic analysis. We found that the optimum input data settings were the shrinkage strain of -0.012 and a shrinkage zone in which the maximum temperature reached 500 degrees C or more. From the results, the similarity and the difference between the characteristics of angular distortion in the thermal shrinkage technique and that in the thermal elastic-plastic analysis was discussed based on the inherent strain and the moment. Moreover, the way in which inherent strain based on the both-ends-fixed-bar analogy occurred can explain the agreement in angular distortion in the case of the optimum input data settings. Our results demonstrate that a suitable setting method of input data has been established.