介观尺度切削过程的材料本构关系分析

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By using strain gradient theory, a material＇s constitutive relationship was formulated in the meso-scale cutting process. The constitutive relationship considering the size effect was constructed. Based on the relationship, the material＇s stress-strain was studied under different cutting conditions. The results show that the material behaviors is approached to Johnson-Cook（JC） model gradually with the increase of cutting depth;if the rake angle becomes large, the shear angle and internal stress of material increase, and the size effect becomes more obvious, thus, the rake angle shall be bigger properly for the meso-scale cutting. Also, the tool edge radius affects the material behaviors significantly, the size effect becomes more obvious with the decrease of the radius. It must be small enough to realize the meso-scale cutting.应用应变梯度理论,建立了考虑尺度效应的介观切削材料本构关系;应用建立的本构关系对于不同切削条件时材料的应力-应变关系进行了分析研究。研究表明：随着切削厚度的增加,材料力学性能曲线逐渐向宏观Johnson-Cook（JC）模型靠近;当前角增大时,剪切角随之增大,材料内部的应力加大,材料的尺度效应越明显,因此适当增大刀具前角有利于介观尺度切削;切削刃半径对材料性能的影响比较明显,随着切削刃半径的减小,材料性能的尺度效应逐渐显著,要实现介观尺度切削,刀具切削刃半径必须极小。