Incipient Plastic Phenomena in Machining of Copper
Open Access
- Author:
- Du, Fei
- Graduate Program:
- Industrial Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- July 15, 2013
- Committee Members:
- Christopher J Saldana, Thesis Advisor/Co-Advisor
- Keywords:
- incipient cutting
chip formation
plastic deformation
particle image velocimetry - Abstract:
- Past studies on the topic of material removal have emphasized study of deformation phenomena at steady-state; models and analyses in this regime are well established. In contrast, the plasticity associated with the incipient or transient regime has received far less attention. While transient phenomena are not typically critical in understanding the deformation field of conventional machining, recently-developed manufacturing technologies (e.g., vibration-assisted machining, surface texturing) make use of this regime to improve process/product performance. In this regard, detailed understanding of incipient plastic phenomena is needed to better understand potential for process-level improvements. In this thesis, the transition from incipient stage to steady-state cutting was investigated in plane strain deformation of a model material system - pure copper. To measure the time-variant deformation in the incipient cutting regime, a numerical method based on a particle image velocimetry (PIV) algorithm was developed and applied to quantitatively measure deformation fields during chip formation. Characterization of the evolution to steady-state was made by PIV, hardness mapping and cutting load analysis, and all were shown to be capable of accurately predicting the length of incipient cutting stage. The incipient plastic phenomena in chip formation were analyzed under different cutting conditions and the effects of cutting parameters – tool rake angle and depth of cut – on the length of incipient cutting stage were investigated. A linear relationship between the incipient regime length and the two controllable parameters was found and was rationalized by considering the effects of each on the length of the shear plane in deformation. These results are potentially useful as a basis for designing parameters in processes that make use of transient phenomena in deformation.