介观尺度切削无氧铜本构模型建立与仿真

ESTABLISHMENT AND SIMULATION OF OFHC COPPER CONSTITUTIVE MODEL IN MESOSCALE CUTTING PROCESS

微细加工会产生介观尺度下的尺度效应,应用基于位错机制的应变梯度塑性理论,考虑材料的微观结构特性,建立介观尺度下的材料本构模型,可解释微细加工中产生的尺度效应现象。对理论推导出来的介观尺度下的材料本构模型进行分析研究,得到不同切削条件下的应力-应变曲线及仿真结果。研究表明,随着切削厚度的不断增加,材料的应力-应变曲线会逐渐趋向于宏观切削时的应力-应变曲线。当刀具的前角不断增大,材料的应力会随之增加,即材料所表现的尺度效应会更加明显。刀具的前角对于切屑的形成也会产生很大的影响,当刀具前角较小时会更有利材料在前刀面堆积而形成切屑。刀具切削刃半径是微细加工中最小切削厚度现象产生的根本原因。随着刀具切削刃半径的减小,材料所表现的尺度效应也更加明显。

Micro-machining can produce size effect under mesoscopic scale,by using the strain gradient plasticity theory of dislocation mechanism,considering the microstructure characteristics of the material,the material constitutive model under mesoscopic scale is established,which can be used to explain the size effect of micro-machining.The material constitutive model under the mesoscopic scale derived from the theory is analyzed and studied,and the stress-strain curves and simulation results under different conditions are obtained in this article.The research shows that with the increase of cutting thickness,the stressstrain curve of the material will tend to the stress-strain curve of macro cutting.As the rake angle of the tool increases,the internal stress of the material increases accordingly,and the scale effect of the material becomes more obvious.The rake angle of the tool also has a great influence on the formation of the chip,and the smaller tool rake angle is more conducive to accumulating material and thus forming chips.The cutting edge radius of the tool is the root cause of the phenomenon of minimum cutting thickness.With the decrease of the cutting edge radius,the scale effect of the material becomes more prominent.