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Development of An Extended Molecular Dynamics Capable of Simulating EmergentProcess and Its Application to Brittle/Ductile Transition Phenomena

能够模拟突现过程的扩展分子动力学的发展及其在脆性/延性转变现象中的应用

基本信息

批准号：
14550102
负责人：
INAMURA Toyoshiro
金额：
$ 1.6万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

1. The concept of Renormalization Group Molecular Dynamics (RGMD) has been proposed. The RGMD consists of Renormalized Molecular Dynamics (RMD) for simulating macroscopic phenomena and Inverse RMD (IRMD) for simulating microscopic phenomena that occur in the RMD. The RMD and IRMD interact each other such that emergent processes can be simulated.2. New inter-particle potentials to be used in the RMD have been constructed based on energy conservation principle in renormalization process. The derived potentials can reproduce size effect of material strength as well as the decrease of strength at high temperature.A method to compute transformations from atomic arrangement in clusters to cluster arrangement around the cluster has been proposed to evaluate the inter-particle potentials described in (3) numerically. The results of numerical examples for carious cases show that the proposed method can construct transformations with satisfactory accuracy.4. The necessity of introducing viscosity in computing particle motion in the RMD has been clarified based on the physical phenomena through which viscosity appears. Then an extended MD algorithm for computing particle motion with viscosity has been developed. The result of simulation obtained using this algorithm with regard to tensile test of a copper specimen on micrometer size shows brittle fracture under pulling speed at 100m/s. This result is consistent with experimental ones obtained by impact tensile test.

1.提出了重整化群分子动力学的概念。RGMD由用于模拟宏观现象的重整化分子动力学（RMD）和用于模拟RMD中发生的微观现象的逆RMD（IRMD）组成。RMD和IRMD相互作用，使得涌现过程可以被模拟.根据重整化过程中的能量守恒原理，构造了用于RMD的新的粒子间势。所导出的势能再现材料强度的尺寸效应以及高温下强度的下降。提出了一种计算团簇中原子排列到团簇周围团簇排列转变的方法，数值计算了（3）中描述的粒子间势。对多种情况的数值算例表明，该方法能够构造出具有令人满意精度的变换.从粘性产生的物理现象出发，阐明了在RMD中计算质点运动时引入粘性的必要性。在此基础上，发展了一种计算粘性质点运动的扩展MD算法。用该算法对微米级铜试样的拉伸试验进行了模拟，结果表明，在100 m/s的拉伸速度下，试样发生了脆性断裂。这一结果与冲击拉伸试验结果一致。