Wen LIU
材料科学技术（英文）
The energy dissipation caused by the viscous force has great effects on the flow property of semi-solid metal during rheological processes such as slurry preparing, delivering and cavity filling. Experimental results in this paper indicate that the viscous friction between semi-solid metal and pipe wall, the collisions among the solid particles, and the liquid flow around particles are the three main types of energy dissipation. On the basis of the hydromechanics, the energy dissipation calculation model is built. It is demonstrated that the micro-structural parameters such as effective solid fraction, particle size and shape, and flow parameters such as the mean velocity, the fluctuant velocity of particles and the relative velocity between the fluid and solid phase, affect the energy dissipation of semi-solid metal.PartⅡ：This study investigates the rheological behavior of semi-solid metal. An analytical model of apparent viscosity was built up based on analysis of energy dissipation during rheological processes such as slurry preparing, delivering and model filling. The rheological behavior of SSM slurries was described by an analytical model in terms of micro structural parameters, which consist of effective solid fraction, particle size and shape, and flow parameters such as mean velocity, fluctuation velocity and relative velocity between liquid and solid phase. The model was verified in the experiment of A356 alloys with a coaxial double-bucket rheometer. And the maximum relative error between the theoretical value and measured value is less than 10%. The results of experiment and theoretical calculation also indicate that the micro structural parameters and flow parameters are two major factors that affect the apparent viscosity of semi-solid alloys, and fluctuation velocity and relative velocity between liquid and solid phase are the key factors to distinguish between steady and transient rheological behaviors.
关键词:
Semi-solid metal
,
能量耗散
,
流变
,
表观粘度
,
模型
姜菊生
,
张伟根
,
郭乙木
,
叶笃毅
材料科学与工程学报
doi:10.3969/j.issn.1673-2812.2000.01.010
通过对45号钢材料在三种不同应力水平下纯弯疲劳试样的拉伸测试,研究了能量耗散随疲劳损伤的变化规律,发现能量耗散这一参量随损伤表现较为敏感,为此,本文提出一种新的损伤参量,且该参量能简单、有效地进行损伤完全分析,预计有工程应用价值.
关键词:
纯弯疲劳
,
损伤
,
拉伸
,
能量耗散
史建平
,
林吉忠
材料科学与工程学报
doi:10.3969/j.issn.1673-2812.2007.01.015
运用热力学理论和最小耗能原理,研究了反复低速冲击下短纤维复合材料的能量耗散与损伤演变,给出了冲击循环下材料耗散能表达式,建立了与复合材料割线模量降低率相关的损伤变量表达式和损伤演变方程.同时,以试验数据为基础,利用导出的损伤变量表达式,绘制出了反复低速冲击下短纤维复合材料的损伤演变曲线,并对曲线趋势进行了分析.
关键词:
热力学理论
,
最小耗能原理
,
反复低速冲击
,
短纤维复合材料
,
能量耗散
,
损伤演变
张劲军
,
张帆
,
黄启玉
,
严大凡
工程热物理学报
基于流体流动的剪切速率与能量耗散率、以及能量耗散率与流体温升速率的关系,提出了根据搅拌过程中流体温升速率计算绝热搅拌槽内流体平均剪切速率的方法,并针对一个实验室用的小型高速搅拌系统,建立了流体平均剪切速率与流体黏度及搅拌转速关系的经验模型.本方法确定的是全槽流体的平均剪切速率,其应用不受叶轮类型的限制,可用于湍流搅拌,弥补了Metzner-Otto方法的若干不足.对于控温搅拌槽,可先在绝热条件下确定平均剪切速率与搅拌转速、流体流变性参数及体积的关系.
关键词:
搅拌
,
剪切
,
速率
,
能量耗散
孙岳霆
,
许骏
,
李一兵
,
徐晓庆
,
刘成
无机材料学报
doi:10.3724/SP.J.1077.2014.13447
高能量耗散密度材料的研发是防护工程领域的研究热点.纳米多孔材料具有超大的比表面积,其与液体的相互作用能够耗散大量外界能量,因此在车辆碰撞安全等领域具有出色的应用前景.本研究选取ZSM-5沸石/NaCl溶液系统,通过准静态实验研究该系统的能量耗散行为,并阐明其机理,同时参数化地研究了沸石的前处理温度(600～1100℃)及溶液的NaC1浓度(0～2 mol/kgH2O)对系统能量耗散性能的影响.结果表明:该系统在准静态加载条件下具有较高的能量耗散密度,达到12 J/g,且可重复使用;该系统的工作性能可在较大范围内调节,其能量耗散密度与沸石前处理温度正相关,与NaCl浓度负相关;其工作压强与沸石前处理温度及NaCl浓度均正相关.本研究为开发智能、可控和高效的能量耗散系统提供了必要的基础理论与实验依据.
关键词:
纳米多孔材料
,
能量耗散
,
前处理温度
,
离子浓度
,
安全防护
