An assessment of welding distortion analysis using thermal shrinkage technique for a construction machinery structure

Abstract

The thermal shrinkage technique, which uses shrinkage strain and shrinkage zone to calculate welding distortion, is expected as a simple simulation to predict the welding distortion of large weld structures. In previous studies, parametric study was performed for bead-on-plate welding and optimum input data settings was clarified, which were the shrinkage strain of −0.012 and a shrinkage zone in which the maximum temperature reached 500°C or more for structural steel. In this research, the thermal shrinkage technique with established input data settings was applied to a construction machinery structure to validate whether the input data settings obtained in the previous study for test specimens is applicable to large weld structures. The analytical model is a construction machinery structure with dimensions of 3.9 m in length, 2.7 m in width, and 0.9 m in height, and has a 40-pass fillet welded joint. The welding distortion analysis using thermal shrinkage technique was conducted with the optimum input data settings. Thermal elastic-plastic analysis considering moving heat source was also performed to compare the numerical results by the thermal shrinkage technique and thermal elastic-plastic analysis. Numerical results revealed that the displacement distribution after 40-pass welding of the construction machinery structure obtained by the thermal shrinkage technique was in good agreement with that obtained by thermal elastic-plastic analysis. A more detailed evaluation showed that the displacement in each welding pass obtained by the thermal shrinkage technique accurately reproduced that obtained by thermal elastic-plastic analysis. The calculation time of the thermal shrinkage technique was 1/7 for the construction machinery compared with thermal elastic-plastic analysis, which clarified that calculation time could be shortened. Our results show that the thermal shrinkage technique with optimum input data settings could be applicable to large weld structures to predict welding distortion.

Keywords

• welding distortion
• thermal shrinkage technique
• thermal elastic-plastic analysis
• numerical simulation
• finite element method
• large weld structure