Three Dimensional Numerical Simulation of Various Thermo-mechanical Processes by FEM (Report I) : Methods for Improving the convergence of 3-D Analysis of Welding(Mechanics, Strength & Structural Design)

概要

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The three dimensional thermal-elastic-plastic analysis by FEM has been paid great attention recently with the development of computer techniques, since this method provides the possibility to analyze complex problems such as the welding processes which undergo a high temperature cycle and exhibit temperature dependent material properties. Because of the temperature dependent material nonlinearities and geometrical nonlinearity due to the large deformation during welding, it is a very important problem how to ensure the computing accuracy and get a stable solution, especially at high temperature stages. The investigations show that the stages with drastic change, such as the transition from elastic to plastic, unloading stage and stage in which rapid changes of material properties with temperature occur suffer from the numerical error. Also the mesh division and the temperature increment are found to show significant influences to the accuracy and convergence of the solution. To improve the accuracy, weight factors from elastic stage to plastic stage considering the temperature dependency of material properties have been introduced. In addition to this, some other methods for improving the convergence are introduced. The effectiveness of the proposed methods is demonstrated through a 3-D analysis of welding as an example in this report.
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