- 學位論文
以分子動力學模擬受拉伸之Cu/Al雙金屬微結構的應力與應變行為
A Molecular Dynamics Simulation of Stress and Strain Behaviors of Cu/Al Bimetal Micro-Structure under Tensile Force
摘要
本研究是以分子動力學來模擬Cu/Al雙金屬在裂縫的存在與否，以及在不同排列方式下，探討應力的分布與微觀結構的變化。模擬的方法是利用Tight-Binding勢能函數與Verlet鄰近表列法，來描述金屬分子間的作用力；並利用Gear五階預測修正法計算系統中原子因外力產生位移後的位置、速度及加速度。 由模擬的結果發現：無論試件有無裂縫，微觀世界裡皆存在一預應力值，且裂縫存在時為正值；當試件受到拉伸影響至破斷後皆會產生微小的應力震盪，尤其是在有裂縫的情況下較為明顯。當試件存在裂縫時，無論Cu/Al雙金屬的排列方式為何，破斷面皆會自裂縫所處位置擴展。當試件不存在裂縫時，起始缺口會於試件較薄處產生；倘若厚度相當，則會於抵抗能力較弱處(例如:不同原子之界面)產生。
並列摘要
In this study is the use of molecular dynamics to simulation cu/al bimetal in the presence or absence of cracks, as well as in different permutations way to explore the stress distribution and micro-structure changes. The Simulation method is to use the Tight-Binding potential function method and Verlet table columns adjacent to describe metal intermolecular forces; and use the Gear fifth-order correction prediction method to calculate the atom due to an external force displaced position, velocity and acceleration. According to The simulation results that: either the specimen presence or absence to cracks,in the microscopic system exists a prestress value, and the presence of cracks is positive; specimen is stretched to the breaking effect will produce a slight rear shock stress, especially in the there are cracks in the case are obvious. When the cracks in the specimen, either the copper / aluminum bimetal what order, breaking sections will extend from the crack location. When the specimen is not present cracks,gaps starting from where the specimen thinner area.