周期分布缺陷对韧性材料高应变率拉伸碎裂过程的影响  

Effects of periodically-distributed defects on ductile fragmentation process of materials under high strain-rate tension

作　　者：郑宇轩[1,2] 周风华[2] 胡时胜[1] 

机构地区：[1]中国科学技术大学中国科学院材料力学行为和设计重点实验室,安徽合肥230026 [2]宁波大学教育部冲击与安全工程重点实验室,浙江宁波315211

出　　处：《爆炸与冲击》2013年第2期113-119,共7页Explosion and Shock Waves

基　　金：国家自然科学基金项目(10972108);宁波市科技局配套项目;宁波大学王宽诚幸福基金项目~~

摘　　要：为研究初始缺陷对材料高应变率碎裂过程的影响,采用有限元方法模拟了具有周期性几何缺陷的韧性金属圆杆在高应变率拉伸过程中的碎裂现象。模拟结果表明:(1)与无初始缺陷的韧性杆件相比,具有一定幅值的初始缺陷的杆件在同等拉伸速度下发生断(碎)裂的时刻一般提前;(2)初始缺陷对碎片的尺寸和大小分布影响明显,在一定的应变率范围内,周期性缺陷完全控制了韧性材料碎裂过程中产生碎片的个数,可称这个碎裂过程为'缺陷控制碎裂';(3)改变初始缺陷的空间间距和幅值,出现'缺陷控制碎裂'的应变率窗口将发生明显变化。进一步讨论了具有2种幅值的复合缺陷对拉伸碎裂过程的影响。To explore the effects of the initial defects on the fragmentation processes of materials at high strain rates, an explicit FEM code was used to simulate the dynamic fragmentation processes of thin elastic-plastic bars undergoing uniform high strain-rate tensile deformations. The thin bar was prescribed with periodically-distributed geometrical defects. Numerical simulations display that the bars with the initial defects usually break into pieces earlier than those without defects. For the thin bars with the periodically-distributed defects, there exists a strain rate region in which the fragmenta- tion process is completely controlled by the defects. This fragmentation process is called the defect- controlled fragmentation process. The spacing and the size of the defects also affect the fragmentation process by moving the strain-rate region of the defect-controlled fragmentation. The effects of the combined defect distribution on the ductile fragmentation process were also discussed.

关 键 词：固体力学 初始缺陷 有限元法 韧性材料 缺陷控制碎裂 碎片数 

分 类 号：O346.1[理学—固体力学]