Date of Graduation

2002

Document Type

Thesis

Degree Type

MS

Committee Chair

Victor H. Mucino

Abstract

In large steel fabrication industries such as shipbuilding, and high-speed train guideway, the problem of residual stresses and overall distortion has been and continues to be a major issue. In the last few decades, various research efforts have been directed at the control of the welding process parameters aiming at reducing the distortions and residual stress effects. Yet, in actual practice, large amounts of resources are still being spent in reworking welds, which in turn increases the production cost and delays work completion. It is assumed that in order to reduce the residual stresses and distortions from a welding operation, it is necessary to understand the effects of welding process parameters on the responses. In this thesis, a study has been conducted to assess the effects of heat input, speed rate, restraint, plate curvature, and gap on arc welding responses as applied to steel welding. A single pass corner joint arc welding has been chosen in this study. The arc welding process is simulated using Finite Element Method (FEM) program ANSYS®. The simulations were carried out using a two-step process; non-linear heat transfer that produces the dynamic temperature distribution throughout the weld seam and the plates, and the elasto-plastic analysis, which yields residual stresses, strains, and displacement. The “birth and death” element feature was used in the finite element model to simulate the welding process. The responses along several longitudinal cross sections were obtained after the plate cooled down to room temperature. The results show that all parameters, except for the gap between the plates have a significant effect on the responses. Relationships between the parameters and the responses have been drawn based on the simulation results.

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