Title: A finite element model for micro machining considering size effect of material behaviour and tool geometry

Authors: Hongtao Li, Xinmin Lai, Boshen Fu, Chengfeng Li, Zhongqin Lin, Jun Ni

Addresses: State Key Laboratory of Vibration, Shock and Noise, Shanghai Jiao Tong University, 200030, China. ' State Key Laboratory of Vibration, Shock and Noise, Shanghai Jiao Tong University, 200030, China. ' State Key Laboratory of Vibration, Shock and Noise, Shanghai Jiao Tong University, 200030, China. ' State Key Laboratory of Vibration, Shock and Noise, Shanghai Jiao Tong University, 200030, China. ' State Key Laboratory of Vibration, Shock and Noise, Shanghai Jiao Tong University, 200030, China.'S.M. Wu Manufacturing Research Center, University of Michigan, Ann Arbor, 48109, USA

Abstract: This paper presents a finite element model that is capable of describing the main characteristics in micro machining processes. By using strain gradient plasticity, a modified Johnson-Cook constitutive equation is formulated to model the size effect of material behaviour at micron level as well as the main features in macro machining processes. Based on the material model, a finite element model is developed, considering size effect, cutter edge radius and fracture behaviour. Size effect and chip formation are investigated in detail by FE simulations, applying the developed model. Two research findings can be drawn from the results: size effect of micro machining can be well explained by modelling material behaviours at micron scale using strain gradient plasticity; from the chip formation studies, the minimum chip thickness is proposed to be 0.35 times of the cutter edge radius when the rake angle is 10 degrees and the radius is 2 µm.

Keywords: micromachining; cutter edge radius; size effect; chip formation; strain gradient plasticity; material behaviour; tool geometry; finite element method; FEM; fracture behaviour; chip thickness; simulation.

DOI: 10.1504/IJMPT.2008.018031

International Journal of Materials and Product Technology, 2008 Vol.31 No.2/3/4, pp.339 - 353

Published online: 27 Apr 2008 *

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