基于应变梯度塑性理论的纪念币压印成形数值模拟  

Coining Simulation of Commemorative Coins Based on Strain Gradient Plasticity Theory

作　　者：易国锋[1] 李巧敏[2] 钟文[2] 柳玉起[2] YI Guofeng;LI Qiaomin;ZHONG Wen;LIU Yuqi(School of Mechanical Engineering, Hubei University of Technology, Wuhan, 430068;State Key Laboratory of Materials Processing and Die ＆ Mould Technology, Huazhong University Science and Technology, Wuhan, 430074)

机构地区：[1]湖北工业大学机械工程学院,武汉430068 [2]华中科技大学材料成形与模具技术国家重点实验室,武汉430074

出　　处：《中国机械工程》2018年第11期1369-1374,共6页China Mechanical Engineering

基　　金：国家自然科学基金资助项目(51275184)

摘　　要：为了准确体现纪念币压印成形工艺中由于精细浮雕导致的尺寸效应,从Taylor位错模型出发,基于应变梯度塑性理论,建立了压印成形的本构方程。采用纳米压痕试验,获得了Ag999的材料内禀尺寸以及统计存储位错密度和几何必须位错密度的非线性耦合关系。将建立的本构方程用于计算某钥匙纪念币压印成形过程中的压印力变化曲线,并与试验结果进行对比,结果表明,建立的本构方程能够体现压印成形工艺中的尺寸效应,可有效改善压印力的预测精度。To exactly describe the size effects caused by the fine patterns in coining simulation ofcommemorative coins,a constitutive equation was developed based on the Taylor dislocation model and thestrain gradient plasticity theory. A nanoindentation test was conducted to obtain the mechanical properties ofthe Ag999 material,including the intrinsic material length and the nonlinear coupling relation between thestatistically stored dislocation density and the geometrically necessary dislocation density. The proposedconstitutive equation was applied to calculate the coining processes of a key-shaped coin,with the obtainedcoining force curves compared with the experimental ones. It is demonstrated that the proposed constitutiveequation is capable of reflecting the size effects in coining and improves the accuracy in predicting coining forces.

关 键 词：纪念币 压印成形 Taylor位错模型 应变梯度塑性 尺寸效应 

分 类 号：TP391.9[自动化与计算机技术—计算机应用技术]