An Improved Plasticity-Based Distortion Analysis Method for Large Welded Structures

摘要

The plasticity-based distortion prediction method was improved to address the computationally intensive nature of welding simulations. Plastic strains, which are typically first computed using either two-dimensional (2D) or three-dimensional (3D) thermo-elastic-plastic analysis on finite element models of simple weld geometry, are mapped to the full structure finite element model to predict distortion by conducting a linear elastic analysis. To optimize welding sequence to control distortion, a new theory was developed to consider the effect of weld interactions on plastic strains. This improved method was validated with experimental work on a Tee joint and tested on two large-scale welded structures - a light fabrication and a heavy fabrication, by comparing against full-blown distortion predictions using thermo-elastic-plastic analyses. 3D solid and shell models were used for the heavy and light fabrications respectively to compute plastic strains due to each weld. Quantitative comparisons between this method and thermo-elastic-plastic analysis indicate that this method can predict distortions fairly accurately - even for different welding sequences, and is roughly I-2 orders of magnitude faster. It was concluded from these findings that, with further technical development, this method can be used for optimizing welding sequences.