流动应力下降尺度效应的数值模拟

The Numerical Simulation of Decreasing Flow Stress Scale Effect

采用率相关晶体塑性本构关系及弹塑性大变形增量有限元方法,通过在晶粒尺寸相同条件下模拟不同尺寸微型铜圆柱体镦粗实验,对流动应力下降尺度效应现象进行了数值模拟研究,获得了与实验及表面层模型较为一致的结果.结果表明,随着坯料尺寸的减小,流动应力逐渐下降;晶体塑性理论能够解释并描述流动应力下降尺度效应现象,并在一定程度上对流动应力下降幅度做出预测.

With rate-dependent crystal plasticity constitutive relation and elastoplastic large deformation incremental finite element method,under the condition of same grain size,by simulating upsetting tests of different dimension micro copper cylinders,decreasing flow stress scale effect was simulated,and consistent results with the tests and surface layer model were obtained.The results show that,with the decrease of billet dimensions,flow stress is decreased;the decreasing flow stress scale effect can be explained and described by crystal plasticity theory,and the decrease of flow stress can also be predicted to a certain(extent.)