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Finite element analysis of heat distribution and cooling in welding

Sykora, Alois Jan (2015). Finite element analysis of heat distribution and cooling in welding. Bachelor of Engineering (4th Year Project) Thesis, Charles Darwin University.

Document type: Thesis
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Author Sykora, Alois Jan
Title Finite element analysis of heat distribution and cooling in welding
Institution Charles Darwin University
Publication Date 2015
Thesis Type Bachelor of Engineering (4th Year Project)
Abstract Welding is an important aspect of building and manufacturing as it is one of the most common methods of joining metals together. An important consideration in design when welding is the evaluation of the heat distribution that occurs during welding and the cooling rate afterwards, as these have an effect on the microstructure of the metal in the vicinity of the weld. These changes in the microstructure have effects on the strength, toughness, and fatigue strength of the weld and base metal, and as such must be factored into any design to ensure that it is safe and fit for purpose. Empirical and numerical methods have been developed in the past to determine the heat distribution in welding, the first and most notable numerical method was developed by Daniel Rosenthal and published in 1935 [4]. This method contains many idealised assumptions, and is therefore satisfactory for use up to a certain point when designing. Finite Element Analysis (FEA) is a method that discretises a model into a mesh of nodes, with solutions for the temperatures at the nodes being calculated at defined steps in time. FEA allows for precise solutions for many types of analysis, but can be time consuming to set up and may require prolonged computing times due to the large amount of calculations required.

For this thesis, a simplified Finite Element Model is developed in LISA™ Finite Element Software and compared to the Rosenthal welding model. Additionally, experimentation to determine the accuracy and validity of the FEA model will be carried out. In Part A of the thesis, the heat distribution and cooling rates in the welding process have been developed numerically via FEA and compared to the results from the Rosenthal Equations. 

For Part B of the thesis, the numerical results developed through the Rosenthal welding model and Finite Element models were verified by comparison to empirical data obtained through experimentation. To remain consistent with the Rosenthal welding models and the developed Finite Element Model, autogenous TIG welding was employed in order to eliminate bead deposition, as this affects the accuracy of the model through the addition of material that would have to be taken into account in the numerical models. Moreover, TIG welding provided a suitable point source for the addition of heat to the work piece.
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Created: Wed, 23 Sep 2015, 14:46:05 CST by Jessie Ng