Modeling of flow stress in orthogonal micro-cutting process based on strain gradient plasticity theory

The rapidly increasing demand for miniature components machining processes has drawn more attention to micro-machining research. Flow stress has always been a significant base for analyzing plastic deformation in machining processes. However, few studies have been conducted to predict accurately the material flow stress in the micro-cutting processes. In order to describe size effect in micro-cutting, this paper discusses the development of a circular primary deformation zone model, calculates the strain gradient in the primary zone, and presents a new flow stress model based on the theory of strain gradient plasticity. First, a series of orthogonal cutting experiments are performed and flow stress is calculated from the experiment data. Results from the proposed model have been successfully validated with experimentally determined results. It shows that the flow stress in micro-cutting is influenced greatly by the feed rate and the cutting edge radius.

[1]  M. E. Merchant.  Mechanics of the Metal Cutting Process. I. Orthogonal Cutting and a Type 2 Chip , 1945 .

[2]  Steven Y. Liang.  Mechanical machining and metrology at micro/nano scale , 2006, International Symposium on Precision Mechanical Measurements.

[3]  K. Johnson,et al.  The correlation of indentation experiments , 1970 .

[4]  P. Oxley.  Mechanics of metal cutting , 1961 .

[5]  N. Fang,et al.  Slip-line modeling of machining with a rounded-edge tool—Part II: analysis of the size effect and the shear strain-rate , 2003 .

[6]  Hans Kurt Tönshoff,et al.  Three-Dimensional Micromachining by Machine Tools , 1997 .

[7]  A. Eleiche,et al.  Strain-rate effects during reverse torsional shear , 1976 .

[8]  G. Voyiadjis,et al.  Analytical and experimental determination of the material intrinsic length scale of strain gradient plasticity theory from micro- and nano-indentation experiments , 2004 .

[9]  Taylan Altan,et al.  Determination of flow stress for metal cutting simulation : a progress report , 2004 .

[10]  Shreyes N. Melkote,et al.  An Explanation for the Size-Effect in Machining Using Strain Gradient Plasticity , 2004 .

[11]  M. A. Moore,et al.  On the correlation of indentation experiments , 1977 .

[12]  M. A. Elbestawi,et al.  Grain size and orientation effects when microcutting AISI 1045 steel , 2007 .

[13]  D. Parks,et al.  Crystallographic aspects of geometrically-necessary and statistically-stored dislocation density , 1999 .

[14]  G. Pharr,et al.  The indentation size effect in the spherical indentation of iridium: A study via the conventional theory of mechanism-based strain gradient plasticity , 2006 .

[15]  Kai Liu,et al.  Process Modeling of Micro-Cutting Including Strain Gradient Effects , 2005 .

[16]  Olivier Cahuc,et al.  Behaviour law for cutting process , 2006 .

[17]  F. Fang,et al.  Investigations of tool edge radius effect in micromachining : A FEM simulation approach , 2008 .

[18]  Sathyan Subbiah,et al.  Some Investigations of Scaling Effects in Micro-Cutting , 2006 .

[19]  Huajian Gao,et al.  Indentation size effects in crystalline materials: A law for strain gradient plasticity , 1998 .