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以基于梯度塑性理论提出的绝热剪切带内部的局部塑性剪切变形分布的理论表达式为基础,研究10个参数对绝热剪切敏感性的影响。对LIAO及DUFFY给出的Ti-6Al-4V绝热剪切带内部的1条流线的实验结果进行最小二乘曲线拟合。估算绝热剪切带宽度取值不同时的临界塑性剪切应变。理论曲线很好地反映了绝热剪切带内部流线的非线性变形特征。利用不同的临界塑性剪切应变值反算了JOHNSON-COOK模型中的一些参数。研究发现,绝热剪切敏感性随着初始静态屈服应力、功热转化因子和应变率参数的降低而降低,这与密度、热容、环境温度及应变硬化指数的影响刚好相反。所提出的模型可以预测绝热剪切带的宽度由高至低的演变过程,直到达到一个稳定值,这一点DODD和BAI模型做不到。
Based on the theoretical expression of local plastic shear deformation distribution in adiabatic shear band proposed by gradient plasticity theory, the influence of 10 parameters on adiabatic shear sensitivity was studied. The experimental results of 1 streamline inside the Ti-6Al-4V adiabatic shear band given by LIAO and DUFFY were fitted by least square curve. The critical plastic shear strain at different adiabatic shear band widths is estimated. The theoretical curve well reflects the nonlinear deformation characteristics of the streamline inside the adiabatic shear band. Some parameters in the JOHNSON-COOK model are inversely calculated using different critical plastic shear strain values. The results show that the adiabatic shear sensitivity decreases with the decrease of the initial static yield stress, the heat-transfer factor and the strain rate, which is just the opposite of the density, heat capacity, ambient temperature and strain hardening index. The proposed model can predict the evolution of the adiabatic shear band width from high to low until a stable value is reached, which DODD and BAI models can not do.