UBC Theses and Dissertations
Thermal mechanical analysis of interfacial behavior in aluminum alloy wheel casting process Wei, Xiaodan
The focus of this project is to improve the understanding of the interfacial heat transfer behavior within the Low-Pressure Die Casting (LPDC) process, which is the main manufacturing process for A356 aluminum alloy wheels, and to develop an improved methodology/expression for calculating the heat transfer across the wheel/die interface. To formulate and assess expressions for the interfacial behavior, a 2D-axisymmetric coupled thermo-mechanical model has been developed in the commercial finite element package, ABAQUS. The model was capable of predicting the thermal history, deformation and the variation of the air gap and pressure along the wheel/die interface. The temperature predictions of the coupled thermo-mechanical model were compared with temperature measurements obtained at Canadian Auto Parts Toyota Inc obtained on a production die. A displacement measurement setup using a high temperature eddy current displacement sensor was designed and tested in a lab setting but not employed in a plant trial due timing issues. Initially, the coupled thermo-mechanical model was run with a temperature dependent interfacial heat transfer coefficient to obtain preliminary air gap and pressure behavior at various locations. Comparisons with the thermocouple measurements suggest that the model is able to generally qualitatively, and at some locations quantitatively, predict the temperature changes from the main physical phenomena occurring during the casting process. The preliminary air gap and pressure predictions were used to develop a temperature, gap size and pressure dependent interfacial heat transfer coefficient based on literature review. The interfacial heat transfer coefficient was implemented in the model, and was found to improve the agreement between the model predictions and measured temperatures, but was prone to numerical convergence issues. A new methodology of incrementally changing the interfacial heat transfer coefficient has been proposed to solve the issues. The methodology was implemented in an EXCEL spreadsheet to test it and the calculated interfacial heat transfer coefficients were found to be continuous, reflecting the effects of air gap and pressure evolution. The methodology and corresponding algorithm should be further developed for use in an ABAQUS model in the future.
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