A Numerical and Experimental Investigation of the Machinability of Elastomers

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Title: A Numerical and Experimental Investigation of the Machinability of Elastomers
Author: Yan, Jun
Advisors: Zhilin Li, Committee Member
Kara J. Peters, Committee Member
John S. Strenkowski, Committee Chair
Eric C. Klang, Committee Member
Abstract: The machinability of elastomers is investigated in this dissertation. The main objective of this research is to determine the favorable machining conditions for which elastomers can be machined with a good surface finish. Both orthogonal cutting experiments and finite element model simulations were conducted to achieve this goal. In the orthogonal cutting tests, a wide variety of cutting parameters were examined. Cutting forces, machined surface roughness and temperature were measured to evaluate the effects of various parameters. Rake angle and workpiece temperature were found to have a significant effect on the machined surface roughness during cutting. Large rake angle tools and cryogenic machining produced a smooth machined surface with corresponding continuous ribbon-like chips. In contrast, small rake angle tools generated a rough machined surface. A plane strain finite element cutting model was developed using ABAQUS/Explicit for simulating the orthogonal rubber cutting process. The model was used to predict the cutting forces, chip shape, stress and strain contours, the strain energy density field, and strain energy history in the chip and workpiece. Good agreement was found between the predicted and measured cutting forces. The finite element simulations demonstrated the ability of the model to predict the characteristics of rubber cutting process. A tensile stress and strain in the cutting direction in the workpiece machined surface near the tool tip was observed when a smooth machined surface was produced. New insight into the chip formation mechanism of rubber was achieved by using strain energy concepts. The strain energy density near the tool edge was found to be not only larger but it also extended over a larger area when a rough surface was generated. It was found that the strain energy release rate was closely related to the machined surface quality. A large strain energy release rate corresponded to the generation of a rough machined surface. The understanding gained from the finite element models in this research can be used to develop future guidelines for operating conditions that result in a smooth machined surface finish for machining of elastomers.
Date: 2006-08-15
Degree: PhD
Discipline: Mechanical Engineering
URI: http://www.lib.ncsu.edu/resolver/1840.16/4368

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