拉伸情形下孔洞缺陷对单晶镁裂纹扩展影响的分子动力学模拟  

MOLECULAR DYNAMICS SIMULATION OF THE EFFECT OF VOID DEFECTS ON CRACK GROWTH OF SINGLE CRYSTAL MAGNESIUM UNDER TENSILE CONDITIONS

作　　者：柯昌锐 蓝永庭[1] 解远航 丁浩川 华振虎 KE ChangRui;LAN YongTing;XIE YuanHang;DING HaoChuan;HUA ZhenHu(School of Mechanical and Automotive Engineering,Guangxi University of Science and Technology,Liuzhou 545616,China)

机构地区：[1]广西科技大学机械与汽车工程学院,柳州545616

出　　处：《机械强度》2024年第5期1192-1199,共8页Journal of Mechanical Strength

基　　金：国家自然科学基金项目(12262003,11862002);广西自然科学基金项目(2022GXNSFAA035537);广西科技大学博士基金项目(21Z13)资助。

摘　　要：采用分子动力学方法对预设裂纹和孔洞的单晶镁模型进行了沿C轴拉伸加载的数值模拟,研究在镁晶体中不同位置的孔洞缺陷对裂纹扩展的影响。模拟结果分析表明,在相同特征尺寸下,孔洞会影响单晶镁模型的屈服强度,不同孔洞位置的模型屈服强度不同,其中当孔洞位于裂纹[101ˉ0]方向时,模型的屈服强度最低。孔洞能在一定程度上缓解裂纹在该方向上的应力集中,影响裂纹的孪晶扩展速率。裂纹处靠近孔洞侧的孪晶生长速度相对较慢,其中孔洞位于裂纹[101ˉ0]方向时,孪晶生长速度最慢。孔洞对裂纹的扩展方向影响较小,一般情况下裂纹与孔洞合并后沿拉伸方向扩展,整体呈现比较对称的锥面扩展,但孔洞位于裂纹[0001]方向时,裂纹并未与孔洞出现明显的联合现象。The numerical simulation along the C-axis stretching process of a single crystal magnesium model with preset cracks and void defects was carried out by molecular dynamics method,and the effect of void defects at different positions on crack propagation in single crystal magnesium was studied.The simulation results show that under the same characteristic size,the yield strength of the single crystal magnesium model is affected by the voids at different location.When the voids are located in the crack[101—0]direction,the yield strength of the model is the lowest.The void can alleviate the stress concentration of the crack in the void direction,and affect the twins growth rate of the crack.The twin growth rate near the void of the crack is relative slowly,and the twin growth rate is the slowest when the void is located at[101—0]direction.The voids have a little influence on the propagation direction of the crack.Generally,the crack extends in the tensile direction after combining with the voids,and the overall appearance is a more symmetrical cone expansion.But,when the voids are located in the crack[0001]direction,there is no obvious connection between the cracks and the voids.

关 键 词：单晶镁 孔洞 裂纹 孪晶 分子动力学 

分 类 号：O346.1[理学—固体力学] TG146.22[理学—力学]