Papers by Author: He Yu

Abstract: The finite element model of coupling the thermal field with structural analysis is proposed in order to analyze the thermo-stress of casting ladle structure. The thermal fields of casting ladle with refractory lining structure are computed according to the thermal properties of materials and boundary conditions. Numerical simulation shows that that computed outer temperatures of casting ladle agree with measured ones. The thermo-stress of casting ladle structure is simulated by taking thermal loadings as the loading conditions of the steel shell structure. Material behaviors were described by the Drucker–Prager plasticity model and Von Mises yield criterion. Calculation results of thermo-stress fields shows the outer shell structure is safety under the action of thermal loadings.

Abstract: Owing to localized heating by the welding process and subsequent rapid cooling, the residual stresses can arise in the weld itself and in the base metals. The prediction procedures of the residual stresses in welding process were presented by using finite element techniques. The bilinear elastic-plastic material model based on Von Mises yield criterion was developed. The material non-linearity of weldment and welding fluid was dealt with using an incremental technique. Inside each step, the Newton-Raphson iteration method was utilized. A fully coupled thermo-mechanical two-dimensional analysis was performed with finite element method. The model applied in this study adopts the technique of element birth and death to simulate the weld filler variation with time in multi-pass welded joints. The effects of welding speed on residual stresses are discussed.