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Analysis of welding distortion using qualitative and semi-qualitative techniques

University of British Columbia

In planning and design of engineering projects, engineers are often required to decide upon a course of action irrespective of the completeness and accuracy of available information. With the fast development of computer technology, many numerical analysis tools have arisen to assist engineering decision-making based on complete design information, which is, however, rarely available at most design stages. Little has been done to help engineers make sound decisions when complete design information is not available. Qualitative and Semi- Quantitative Reasoning, a branch in the field of Artificial Intelligence, has the ability of analyzing "ill"-defined problems using sound and clear arguments which are based on facts. This thesis is an attempt to tackle "ill"- defined engineering problems with the above mentioned reasoning techniques. This thesis revolves around the topic of shrinkage and distortion in welded structures. Steel fabrication frequently involves the joining of components by welding. Each component must be fabricated to particular dimensional tolerances. Distortion caused by welding is a frequently occurring problem that makes it difficult to estimate the dimensions of the finished structures and thus increases the fabrication costs. Welding distortion is a poorly quantified phenomenon controlled by many factors that are difficult to describe numerically. The characteristics of the distortion problems make the traditional numerical analysis very arduous and expensive to apply. Due its high complexity, for many years, welding distortion problems have been approached primarily empirically or by trial and error, and uncertain design factors cannot be effectively considered. In this thesis, a computer software tool was developed using qualitative and semi-quantitative techniques, attempting to solve complex welding distortion problems with unclearly specified design factors. With the assistance of this software tool, it is hoped to make the efforts of predicting and controlling welding distortion become more of a science rather than an art.

Thesis/Dissertation

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2009-05-28

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http://hdl.handle.net/2429/8420

Civil Engineering

University of British Columbia

UBCV

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