基于应变率影响的纳晶材料本构模型

PDF全文下载：2015040398

吴友义， 卞欢， 董淑宏（南京工业大学 机械与动力工程学院，江苏 南京 210009）

摘要： 建立了一种包含规则的晶内相和塑性软化晶界位错堆积区相的双相混合模型来研究应变率对纳米晶材料力学性能的影响。根据相混合模型，建立了一种全新的以位错密度演化机制和应变梯度理论为基础的应力应变本构关系。将本构模型计算结果与实验结果对比发现，两者符合得很好，但数值模拟表现出应变硬化行为。计算发现，由于位错线长度的降低，纳晶材料的应变率敏感系数远远高于粗晶材料。

关键词： 纳晶材料； 位错密度演化； 应变梯度； 应变率

中图分类号： TB 3          文献标志码： AI

nvestigation of Constitutive Modeling for Nanocrystalline

Materials Under Effects of Strain RateWU Youyi, BIAN Huan， DONG Shuhong

(School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing 210009, China)Abstract: To evaluate the influences of strain rate on mechanical behavior of nanocrystalline (NC) materials, a phase mixture model composed of ordered grain interior and plastically softer grain boundary dislocation pile up zone was built. With the help of mixture mode, a new stressstrain constitutive relation was firstly established based on dislocation density evolution and strain gradient theory. The calculated data were then compared with experimental curves and the prediction kept in good agreement with experiment. Duo to the reduction of dislocation line length of NC materials leaded the strain rate sensitivity to be larger than that of coarse grain materials.

Key words: nanocrystalline materials; dislocation density evolution; strain gradient; strain rate

收稿日期： 20140419

基金项目： 国家自然科学基金项目（10872087）.

作者简介： 吴友义（1990—），男，硕士研究生.

文章编号：16726987（2015）04039805； DOI： 10.16351/j.16726987.2015.04.009