Jitai NIU
,
Lihong HAN
,
Chonghao WOO
材料科学技术（英文）
Grain growth and grain boundary sliding are the two main superplastic deformation mechanisms. In the paper, simulation work is focused on the sliding of a Σ13 (111) symmetric twist coincidence grain boundary, a Σ13 (110) asymmetric tilt coincidence grain boundary, and a Σ3 (110) symmetric tilt coincidence grain boundary in Al, and the energies of grain boundary for each of equilibrium configurations are computed. An embedded atom method (EAM) potential was used to simulate the atomic interactions in a bicrystal containing more than 2000 atoms. At 0 K, the relationships between total potential energy and time steps for 3 (111) symmetric twist coincidence grain boundary and Σ3(110) symmetric tilt coincidence grain boundary during sliding at 2 m/s represent the periodic characteristic. However, the relationship between total potential energy and time steps for Σ13 (110) asymmetric tilt coincidence grain boundary represents the damp surge characteristic. It is found that grain boundary sliding for Σ3 (110) symmetric tilt coincidence grain boundary is coupled with apparent grain boundary migration.
关键词:
Aluminum
,
null
,
null
,
null
Lijun HAN
,
Junjie ZHU
,
Lihong HAN
材料科学技术（英文）
The hysteresis unit system was introduced to mechanical structure behavior of the TiNi SMA joint based on the structure characteristics of the martensite variants in the joints, and some functions reflecting its inner structure characteristics and micro-behavior such as density function, phase transformation function were set up from micropoints. Finally, the structure behavior relationship and corresponding mathematic model reflecting the relationship among hysteresis strain, stress and phase transformation strain were provided, which could predict the stress-strain behavior of the TiNi SMA joint to large extent.
关键词:
TiNi shape memory alloy
,
null
,
null
郑桂丽
,
姜丽
,
张志东
液晶与显示
doi:10.3969/j.issn.1007-2780.2010.06.001
根据Erickson-Leslie流体动力学理论,研究了混合排列向列相-共面转换液晶盒的引流效应.在强锚定边界条件下,经过理论推导,得出液晶指向矢与流速的关系方程,进一步通过数值计算得出指向矢分布与时间的关系.发现引流效应加快了指向矢达到平衡态的速度,而且破坏了指向矢分布的瞬态对称性,特别在加电压的初始几毫秒这种现象非常明显.
关键词:
混合排列向列相
,
共面转换
,
引流效应
,
指向矢分布
余永刚
,
王玉强
,
周彦煌
,
陆欣
工程热物理学报
为了探索液体火箭发动机的新型点火方法,设计了一种周期性序列脉冲放电火花的模拟点火装置,该装置采用电机驱动电极转动,在圆周上形成放电火花的时空分布.采用高速录像系统,开展了HAN基液体推进剂LP1846液雾在不同条件下电点火特性的实验研究,结果表明,电极转速在3-5 r/s时,电火花在圆周放电空间内的分布比较密集,电能时空分布比较均匀,LP1846液雾点火效果较好.喷雾场流速、液雾细度与周向放电火花能量分布存在一个最佳匹配关系.
关键词:
液体推进剂
,
喷雾
,
电点火
,
瞬态测量
钱晨
,
杨斌
,
章于川
,
夏茹
,
钱家盛
高分子材料科学与工程
通过动态流变学方法研究了不同配比下聚丙烯/乙烯-丙烯-二烯三元共聚物(PP/EPDM)共混体系相分离行为.结果表明,EPDM与PP相容性不佳,当EPDM质量分数达到20％即已发生相分离,在质量分数为50％时形成双连续相结构,在质量分数50％～60％时发生相反转.采用Cole-Cole曲线、Han曲线、van Gurp曲线等方法表征了PP/EPDM体系相分离行为,其中van Gurp曲线最为敏感.
关键词:
聚乙烯
,
三元乙丙橡胶
,
共混
,
动态流变行为
,
相分离
李艳梅
,
白露
,
王宇
,
杨伟
,
杨鸣波
高分子材料科学与工程
将少量超高分子量聚乙烯(UHMWPE)引入高密度聚乙烯(HDPE)构成共混体系,考察了共混物的动态流变行为随组成、温度、频率的变化规律.研究结果表明,体系储能模量、损耗模量、复数黏度随UHMPWE含量增加而增大;Han曲线斜率均小于2且不存在温度依赖性;Cole-Cole曲线均呈半弧形未表现出相分离特征,说明共混体系在熔体状态下并未发生分相过程;所有试样的时温叠加(TTS)主曲线在低频区并未出现特殊的粘弹松弛行为,而在高频区随着UHMWPE含量增加,时温叠加原理失效现象更加显著.
关键词:
高密度聚乙烯
,
超高分子量聚乙烯
,
共混
,
动态流变行为
