高浓度无机盐乳化基质的触变性研究

该文采用剪切速率扫描、时间扫描方法研究了高浓度无机盐乳化基质的剪切应力、剪切粘度、测定了基质的触变性大小和弹性大小，说明了乳化基质是触变性粘弹体系，从乳化基质的微观结构解释了这些变性机理。     

葡聚糖水溶液触变性及动态黏弹性研究

对葡聚糖水溶液的触变性和动态黏弹性进行了研究。触变性研究中发现,分子量为5．223×10^5,浓度为300mg／mL的溶液形成了触变环,其他葡聚糖溶液未表现出触变性。动态黏弹性研究结果显示,实验过程中改变形变大小对耗能模量与储能模量曲线几乎均不构成影响;随着溶液浓度增大,溶液储能模量和耗能模量均变大,两条模量曲线相交点对应的频率逐渐升高;提高葡聚糖分子量同样可使两种模量增大,对应的交点频率升高。     

井下乳化基质输送流变特性分析

井下乳化基质的流变特性对乳化基质长距离输送压力有很大影响。采用软固体测试流变仪对井下乳化基质在固定剪切率条件下进行了时变性测试,在变剪切率条件下进行了流型测试。测试数据和试验现象表明,乳化基质是一种触变性流体,其流动形态可以用Hershal-Bulkley流变模型来表示,测得的井下乳化基质的本构方程为τ=247.59+56.93γ0.52。在输送井下乳化基质时,可以通过提前进行不破坏其稳定性的低剪切率搅拌的方法降低输送压力。     

压力场中高黏聚对苯二甲酸乙二醇酯的流变行为

利用毛细管流变仪及反向压力腔组件研究了压力场下高黏聚对苯二甲酸乙二醇酯(PET)熔体的流变行为。结果表明,随着剪切速率的增加,高黏PET熔体剪切黏度逐渐降低,表现出明显的"切力变稀"行为,是一种典型的假塑性流体;随着熔体所受压力的增加,高黏PET熔体剪切黏度呈指数增长增加,变化规律符合Barus方程;随着温度的升高,高黏PET熔体的剪切黏度逐渐减小;高黏PET熔体的换算因子为3.4,压力增加与温度下降对剪切黏度的贡献是等效的。高黏PET熔体为非牛顿流体,随着温度的逐渐升高,高黏PET熔体非牛顿指数逐渐增大,高黏PET熔体的流动行为逐渐接近牛顿流体特性。高黏PET熔体的剪切黏度-温度依赖性随压力的增加逐渐增强;高黏PET熔体的剪切黏度的温度敏感性随剪切速率的增加逐渐降低。随着剪切速率增加和温度升高,高黏PET熔体剪切黏度对压力的依赖性逐渐降低。     

改性纳米CaCO3悬浮液流变行为及填充聚酯氨基清漆性能研究

改性纳米CaCO3稀悬浮液基本表现为牛顿流体行为,浓悬浮液表观粘度曲线存在低剪切速率剪切稀化幂律特征区和高剪切速率牛顿区两个区域,并具有明显触变性.改性CaCO3填充聚酯氨基清漆,在柔韧性、硬度、流平性及光泽等方面均优于未改性纳米CaCO3填充清漆.     

纳米纤维素对两性蠕虫胶束线性黏弹性的影响

对两性蠕虫胶束（Z-WLM）溶液添加不同类型纳米纤维素（NCs）后的耐温性能进行了研究,并通过线性流变学方法分析了不同浓度的NCs对Z-WLM的动态黏弹性、触变性、蠕变性等流变行为的影响。研究结果表明,质量分数为4wt%的芥酸酰胺丙基二甲基甜菜碱表面活性剂溶液可形成蠕虫胶束（WLM）结构,具有剪切稀释性、黏弹性、蠕变性及良好的触变回复性等特性。与其它类型NCs相比,长径比大、羧基含量高的NCs对WLM溶液拥有更好的增黏作用,同时可增加体系的松弛时间、弹性模量,延长其剪切黏度及动态模量触变回复时间,改善其蠕变回复性和耐温性,适用于70~100℃的中高温油藏增产作业使用。随着NCs添加量的增加,复合体系的黏弹性和蠕变回复性增强,触变回复性减弱。      

改性纳米CaCO3悬浮液流变行为及填充聚酯氨基清漆性能研究

改性纳米ＣａＣＯ３稀悬浮液基本表现为牛顿流体行为,浓悬浮液表观粘度曲线存在低剪切速率剪切稀化幂律特征区和高剪切速率牛顿区两个区域,并具有明显触变性,改性ＣａＣＯ３填充聚酯氨基清漆,在柔韧性,硬度,流平性及光泽等方面均优于未改性纳米ＣａＣＯ３填充清漆。     

基于能量原理的岩样单轴压缩剪切破坏失稳判据

利用能量原理对倾斜的剪切带-带外弹性岩石构成的系统的稳定性进行了研究。单轴压缩岩样沿轴向的变形被分解为两部分,带外弹性岩石压缩引起的变形和剪切带错动引起的变形。后者与剪切带的相对剪切变形具有简单的几何关系。系统的总势能由剪切带的弹性及耗散势能和带外弹性岩石对剪切带所作的外力功构成。剪切带的弹性及耗散势能与剪切带的体积有关系。剪切带的尺寸由梯度塑性理论确定。将系统的总势能对相对剪切变形求一阶导数(等于零),得到了弹性岩石的平衡条件。将总势能对相对剪切变形求二阶导数(小于零),得到了系统的失稳判据。它综合反映了岩石材料弹性及应变软化阶段本构参数(弹性模量及软化模量)、剪切带之外弹性岩石的尺寸、剪切带的尺寸及系统的结构形式(剪切带倾角)对系统稳定性的影响。失稳判据比以往所得到的失稳判据更严格,更精确,更具有广泛意义。     

基础激励下带金属外层的多黏弹性层纤维增强层合板的动力学模型

以包含三层黏弹性材料、二层纤维增强材料和金属外层的多黏弹性层纤维增强(MVFLM)层合板为例,建立其在基础激励作用下的动力学模型。将坐标系设置在层合板结构的中心层,使用高阶剪切变形理论(考虑多个黏弹性层的剪切应变影响)和经典层合板理论分别对纤维层和金属层进行建模,进而获得MVFLM层合板的位移场函数;将基础激励等效成均布惯性力载荷,基于能量法获得系统的动能、势能和外力功,并利用正交多项式法表示边界条件对应的振型函数,成功求解具有多个黏弹性层的MVFLM层合板的固有频率、模态振型和振动响应;分别通过与已有计算结果进行对比以及实例测试,验证了所建立的动力学模型的有效性。     

基于海藻酸自组装胶体粒子的制备及其乳化性能

用海藻酸(ALG)和溶菌酶(Lys)静电自组装制备胶体粒子,用纳米粒度仪和透射电镜对其尺寸和形貌进行表征,研究了溶菌酶和海藻酸的质量比(WR)对胶体粒子性质的影响,得到了具有最佳WR的胶体粒子。胶体粒子具有球形结构,粒径约为143 nm。这种胶体粒子可二次组装在油水界面稳定水包油型Pickering乳液,研究了pH值和盐浓度对胶体粒子性质和乳化性能的影响。随着pH值的增大胶体粒子和乳液滴粒径均逐渐增大而乳化性能逐渐降低; 随着盐浓度的提高胶体粒子和乳液滴的粒径先减小后增大,乳化性能先提高后降低。乳液均保留了一定的活性。     

Fracture initiation at a sphrerical inclusion in a matrix plastically deformed by shear

The critical strain for fracture initiation of a metallic material with a spherical inclusion has been analysed using EaheIby,s inclusion method forthree types of fracture initiation models including the recovery effect by diffusion of atoms. When the elastic constant of inclusion approaches that of the matrix, the critical strain for fracture initiation becomes large in the case of uniform shear deformation of the matrix. It was found that the critical strain becomes large due to the diffusion of atoms, especially for inclusions of small size and a large elastic constant. The model in which the inclusion is cracked by the localized shear deformation can explain the observed inclusion size dependence of the strain for fracture initiation. The inclusion size dependence of the critical strain for fracture initiation by uniform shear deformation of the matrix is different from that by localized shear deformation. Therefore, it is important to know which mechanism governs the fracture.     

Effects of particulate reinforcement and strain‐rates on deformation and fracture behavior of Aluminum 6061‐T6 under high velocity impact

Aluminum matrix composites (AMC) exhibit an attractive combination of mechanical and physical properties such as high stiffness and low density, which favors their utilization in many structural applications. Thus, increasing the structural applications of AMC is the driving force for the need to adequately understand their deformation and failure mechanisms under various types of loading conditions. In this study, plastic deformation of alumina particle reinforced Aluminum 6061‐T6 matrix composite is investigated and compared to that of an un‐reinforced Aluminum 6061‐T6 alloy at high strain‐rates under compressive loading. Dynamic stress‐strain curves are obtained using direct impact Split Hopkinson Pressure Bar (SHPB). Particulate reinforcement increases the deformation resistance of the aluminum alloy at high strain‐rates. Strain localization along narrow adiabatic shear bands is observed in both the reinforced and un‐reinforced alloy. Whereas the microstructure of shear bands in un‐reinforced alloy showed finer grain size compared to that of the bulk material, the shear bands observed in the AMCs are darker than the bulk material and the reinforcing particles are observed to be more closely spaced along the shear bands.     

Formation of Copper Type Texture in Cold Rolled Aluminum Sheet

The formation process of copper type rolling texture in f.c.c.metals was simulated based on a deformation model considering internal reaction stuesses induced by the neighboring matrix as well as external shear stress induced by rollers.It is indicated that the external shear stress will reduce the brass type texture and increase the copper type texture obviously.     

高应变速率下TC11钛合金动态剪切行为与性能

采用分离式霍普金森压杆（Hopkinson Bar）装置系统,对TC11钛合金进行室温高应变速率（700-2100s^-1）动态剪切试验,通过光学显微镜、显微硬度分析仪、扫描电镜研究了TC11钛合金动态剪切行为、绝热剪切带微观组织与性能。结果表明：TC11钛合金随应变速率的提高绝热剪切敏感性增加;绝热剪切带由过渡区域的变形拉长组织和中间部位的细小晶粒组织组成,具有清晰的剪切变形流线,宽度约为10μm;绝热剪切带内的显微硬度值高于基体组织,是,由应变速率强化和应变强化与热软化相互作用的结果。     

FINITE ELEMENT ANALYSIS OF ANISOTROPIC CONDUCTIVE FILM FOR CHIP ON GLASS PROCESS

Anisotropically conductive film (ACF) is a smart electronic packaging material that consumes minimal space for connecting integrated circuit (IC) chips to a liquid crystal display (LCD) panel or printed circuit board. It consists of an adhesive resin and fine conductive fillers such as metallic particles or metal-coated polymer balls. The fillers are compressed and maintain a certain elastic capability while conducted between electrodes. The size of the contact area and the shape of the fillers are important factors in determining conductivity. The process of applying ACF is modeled into three consecutive steps, and the stress and deformation states are studied by finite element analysis in each. In step 1 of the manufacturing process, external load is applied to compress the conductive particles at a temperature of 190°C so that the matrix resin is in a fluid condition. In step 2, an external load is maintained at this temperature to allow the matrix resin to solidify; then, the load is released and the particles spring back to create tensile stresses in the bonding resin matrix. The last step considers the bonded and conducting ACF cooling from 190°C to room temperature. The state of stress and deformation will be readjusted due to different contraction properties between the filler and matrix resin. The results presented in this paper show that changing the thickness of a coated nickel layer does not clearly affect the conductivity of ACF, and the deformation should be greater than 40% for the stability of conductivity.     

基于SPH方法的剪切流驱动液滴在固体表面变形运动数值模拟研究

光滑粒子流体动力学(SPH)方法是纯拉格朗日粒子方法,可以有效避免网格法在模拟大变形过程中带来的网格扭曲等缺陷,适合模拟含大变形的剪切流驱动液滴在固体表面变形运动过程。在基于CSF模型的表面张力SPH方法基础上,采用新的边界处理方式和界面法向修正方法,引入Brackbill提出的壁面附着力边界条件处理方法,得到了含壁面附着力边界条件的表面张力算法。基于新方法模拟了剪切流驱动液滴在固体表面变形运动过程并与实验结果和VOF方法模拟结果进行了对比验证。结果表明:该方法在处理壁面附着力问题时精度较高,稳定性较好,适合处理工程中剪切流驱动液滴在固体表面变形运动问题。     

剪切增稠胶/碳酸钙复合材料的制备及其抗冲击性能研究

为了提升人体防护装备的轻便性和灵活性,以剪切增稠胶(STG)为基体,并用纳米CaCO₃对其进行补强,制备了缓冲吸能性能优异的剪切增稠STG/CaCO₃复合材料,研究了CaCO₃含量和粒径对STG剪切增稠性能的影响。结果表明:添加CaCO₃后复合材料的最大储能模量比未添加时增加455%;添加的CaCO₃粒径越小,复合材料的剪切增稠性能越优异。通过落锤冲击实验表征了复合材料的抗冲击性能,CaCO₃的填充可使复合材料在具有最小变形量的情况下吸收更多的冲击力。探究了STG剪切增稠和CaCO₃补强的作用机理,指出剪切增稠现象是由交联键的形成和分子链的缠结作用产生的,CaCO₃通过吸能阻裂,分散冲击力产生补强作用。     

Rheological behavior of nasal sprays in shear and extension

The rheological profiles of commercial corticosteroid nasal spray suspensions (Beconase, Nasacort, Flixonase, and Nasonex) were compared using shear and extensional techniques. Thixotropy/shear thinning was investigated (Carri-Med CSL100, concentric cylinder geometry) by (a) the generation of flow curves at low (100 sec-1) and high (1200 sec-1) maximum shear rates and (b) determination of equilibrium shear viscosities at constant shear rates of 10 sec-1, 100 sec-1, or 1200 sec-1. Extensional properties, on which droplet breakup and size depend, were examined using digital camera photography of droplet evolution and the length any trailing filament formed when the suspension was extruded from a 10-ml syringe at 500 microliters/min. All the nasal suspensions were shear thinning and were also thixotropic to varying degrees. The absence of significant thixotropic recovery at short times (5 min) for all the sprays implies that thixotropy is not necessarily the controlling factor for prolonged residence of the spray in the nasal cavity, but rather that it is the high viscosities present in all four sprays, even after structure breakdown. Preliminary extensional flow data identified differences among the four sprays, with extensional filament lengths increasing in the same rank order as the lowest shear rate (10 sec-1) equilibrium viscosities.     

Amplitude Equations for Large-Scale Marangoni Convection in a Liquid Layer with Insoluble Surfactant on Deformable Free Surface

The numerical simulation has been carried out to investigate the motion of a droplet initially near a wall under gravity and confirm the existence of the wall repulsive force on the droplet. The numerical model is developed based on a mass conservation level set algorithm to capture the surface deformation of the droplet. The results show that the wall repulsive force on the droplet initially near the wall plays an important role in the droplet falling process, and the viscosity force affects the oscillatory trajectory of the falling droplet. In addition, the mutual repulsive effect between two droplets is also studied by settling symmetrically two droplets, and the oscillatory mechanism of droplet motion is discussed as well.