单晶γ-TiAl合金纳米切削过程声发射响应的原子模拟  

Acoustic Emission Response to Nano-Cutting Process of Monocrystal γ-TiAl Alloy via Atomistic Simulation

作　　者：姚永军 冯瑞成[1,2] 张隽 曹卉[1,2] 李海燕[1,2] 雷春丽[1,2] Yao Yongjun;Feng Ruicheng;Zhang Jun;Cao Hui;Li Haiyan;Lei Chunli(School of Mechanical and Electronical Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Key Laboratory of Digital Manufacturing Technology and Application,Ministry of Education,Lanzhou University of Technology,Lanzhou 730050,China)

机构地区：[1]兰州理工大学机电工程学院,甘肃兰州730050 [2]兰州理工大学数字制造技术与应用教育部重点实验室,甘肃兰州730050

出　　处：《稀有金属材料与工程》2022年第7期2467-2474,共8页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(52065036);甘肃省自然科学基金(20JR5RA448);兰州理工大学红柳一流学科建设项目。

摘　　要：本工作采用分子动力学方法研究了单晶γ-TiAl合金纳米切削过程的声发射响应。从原子尺度阐述了单晶γ-TiAl合金切削过程中裂纹形成机理。研究发现:切削初期随着切削力持续增大,剪切区域产生周期性的剪切带;与此同时,在高压应力和弹性应力波共同作用下,类晶粒晶界的非晶原子带的产生阻碍了剪切带的持续发射,使主剪切区的应力无法及时通过剪切带释放,产生局部应力集中现象,导致裂纹萌生并扩展;通过对采集的声发射信号分析,压应力会导致切削过程中声发射功率下降。在时域上,通过对微观缺陷演化和声发射功率-频率对比分析,阐述了纳米切削过程中晶格振动、剪切带以及裂纹萌生与扩展的声发射响应特征,并通过聚类分析得到了损伤的功率和频率特性。In this paper, the acoustic emission(AE) response of monocrystal γ-TiAl alloy during nano-cutting process was studied by molecular dynamics method. The mechanism of crack formation in the cutting process of monocrystal γ-TiAl alloy was described at the atomic scale. It is found that periodic shear bands are formed in the shear zone with the continuous increase of cutting force at the beginning of cutting. At the same time, under the combined action of high pressure st ress and elastic stress wave, the formation of the amorphous atomic band in the grain-like grain boundary blocks the continuous emission of the shear band, so that the stress in the main shear zone can not be released through the shear band in time, resulting in local stress concentration, which leads to the initiation and propagation of cracks. By analyzing the collected acoustic emission signal, it is found that the compressive stress contributes to the decrease of acoustic emission power in cutting process. In the time domain, the acoustic emission response characteristics of lattice vibration, shear band and crack initiation and propagation in nano-cutting process were described by analyzing the microdefect evolution and AE power-frequency comparison. At the same time, the power and frequency characteristics of damage were obtained by clustering analysis.

关 键 词：纳米切削 声发射 单晶γ-TiAl合金 分子动力学 

分 类 号：TH161[机械工程—机械制造及自动化]