Acta Physica Sinica
Molecular dynamics (MD) simulation is performed to study the vacancy-interstitial annihilation in crystalline silicon. We choose the Stillinger-Weber potential, which is commonly used for silicon, to describe the interaction between atoms. The system is relaxed under 300K and 1400K respectively. We have found that < 111 > is the preferred recombination direction and propose the presence of an energy barrier in the < 110 > direction. From the calculated value of energy barrier along < 110 > we give a reasonable explanation for the difference between Tang's and Zawadzki's data.
关键词:
molecular dynamics;vacancy and interstitial;diffusion;point-defects;diffusion;mechanisms
徐菊良
,
邓博
,
孙涛
,
李劲
,
蒋益明
金属学报
doi:10.3724/SP.J.1037.2009.00598
利用Thermo-Calc软件并结合金相显微镜,定性研究了2205双相不锈钢在800℃下敏化不同时间后的微观组织演变过程.通过研究扫描速率、介质成分、介质温度和试样表面状态优化了双环电化学动电位再活化法(DL-EPR),并用该优化方法研究了2205双相不锈钢晶间腐蚀敏感性.结果表明:DL-EPR法能定量评价σ相对2205双相不锈钢晶间腐蚀敏感性的影响,随敏化时间延长,σ相含量增多,晶jian 腐蚀敏感性也随之增加.腐蚀形貌的观测验证了这一规律,
关键词:
2205双相不锈钢
,
DL-EPR
,
晶间腐蚀敏感性
,
σ相
张莉
,
马敬红
,
梁伯润
,
余亦华
高分子材料科学与工程
在氮气氛中采用热重分析的方法对热致液晶共聚酯60PHB/PEN的热降解动力学进行了研究.采用Friedman和Chang两种单一加热速率方法对活化能Ea、反应级数n和频率因子Z等降解反应动力学参数进行了分析.讨论了加热速率和计算方法对热稳定性及降解动力学参数的影响.
关键词:
热致液晶共聚酯
,
热降解
,
动力学
,
热稳定性
金属学报
Volu扣ne 27SeriesB1991AUTHOR INDEX CCAO Guanghan(曹光旱)············……6一B科6CAo weijie(曹卫恋)..················……5一B32oCAO Yilin(曹益林)··················……6一B443CHANG Xin(常听)···············……1一B48CHE Guang邻n(车广灿)·············一6一B科0CHEN Erbao(陈二保)···············……6一B410CHEN Jia....
关键词:
徐颖
,
温卫东
,
崔海坡
材料科学与工程学报
doi:10.3969/j.issn.1673-2812.2006.01.020
针对复合材料层板在冲击载荷下,各种损伤的产生和扩展是一个随载荷、时间和空间而演变的过程,发展了复合材料层合板低速冲击逐渐累积损伤预测方法.采用刚度退化技术和改进的Chang-Chang失效准则、显式有限元法来模拟复合材料层合板受到低速冲击下逐渐损伤过程.使用所发展的方法分析了[0m/90n/0m]铺层的复合材料层合板在低速冲击过程中的逐渐损伤扩展,结果表明本文的方法能较好地模拟复合材料层板在低速冲击下的损伤扩展及变形过程,计算结果与实验结果吻合较好;对不同冲击能量下层合板损伤扩展研究表明,冲击能量与分层损伤面积成线性关系.
关键词:
复合材料层合板
,
冲击
,
逐渐累积损伤
,
破坏机理
,
数值模拟
张鹏飞
,
金海波
复合材料学报
建立了有效的复合材料层合板结构冲击损伤分析方法,层合板面内损伤采用改进的Chang/Chang失效准则做判据,得到面内各类损伤形式.层间损伤采用与Mixed-Mode粘接元等效的TIEBREAK接触模拟.利用此分析方法,从复合材料薄壁结构设计需要出发,研究了在低能量冲击下,铺层的层间角度、铺层方向、铺层重叠对层合板结构冲击损伤阻抗的影响规律,并对它们的综合影响进行了总体分析,得到了能提高层合板结构损伤阻抗的铺层顺序设计指导.最后用该设计指导对某种铺层结构进行了重新设计和有限元模拟,验证了该设计指导的可行性和有效性.
关键词:
冲击损伤
,
分层损伤
,
TIEBREAK接触
,
铺层顺序
,
损伤阻抗
LIU Yongning
,
ZHU Jinhua
,
ZHOU Huijiu Xi'an Jiaotong University
,
Xi'an
,
China A.Kildegaard
,
J.A.Kristensen Department of Mechanical Engineering
,
Aalborg University
,
Denmark Dept.of Materials Science and Engineering Xi'an Jiaotong University
,
Xi'an 710049
,
China
金属学报(英文版)
The dynamic fracture toughness of a mild steel has been studied at different loading rates and temperatures.The material exhibits a transition from tough to brittle fracture with the chang- ing loading rate alone.Analysis of the fracture process by the theory of thermal activation suggests that the fracture activation energy approximates to the bond energy of the{100}of a unit cell.The toughness can be resolved into two parts,J-(fd)=J_a+J_l,where J_a is the athermal part,being independent on temperature and loading rate,while J_l=(K/K_o)~(1/n)exp(Q_f/nkT),which controls the fracture process is temperature and load- ing rate dependent.The transition of fracture mechanism caused by both temperature and loading rate is associated with the thermal movement of atoms.
关键词:
mild steel
,
null
,
null
,
null
