机械式高速混合机内部多粒径颗粒混合特性仿真

采用离散单元法(DEM)对机械式高速混合机内部4种不同粒径亚克力球形颗粒组成的颗粒群的运动混合过程进行数值模拟,分析颗粒混合特性。结果表明,快速混合区域主要集中在混合机中下部,混合机内部颗粒在搅拌桨作用下呈现连续螺旋上下运动状态,中心形成漩涡,高速飞刀有效地防止颗粒团聚;高速混合机的特殊结构以及大小颗粒各异的流动行为,导致颗粒在静止过程中边缘出现少量小颗粒偏析现象;颗粒受力与速度随着高度的增加逐渐减小,并且越高层颗粒受力与速度降低越慢,颗粒尺寸越大颗粒受力与颗粒速度越大,高速旋转的颗粒受到较大离心力作用,使得颗粒法向力大于切向力,颗粒尺寸越大,法向力与切向力差距越大。     

新型螺带桨叶结构对颗粒混合效果的影响

为提高立式锥形混合机的颗粒混合效果，设计一种新型错位断带式螺带桨叶结构；通过数值模拟方法研究错位断带式和连续式2种螺带桨叶结构的颗粒混合过程，并探讨错位断带式螺带叶片上、下层叶片的错位距离、错位高度和螺距比对混合效果的影响；通过实验验证模拟结果的正确性。结果表明：根据实验结果计算得出的错位断带式和连续式螺带桨叶结构的混合机内颗粒的平均混合指数分别为0.922、 0.861,根据模拟结果计算得出的平均混合指数分别为0.985、 0.941,实验结果比模拟结果偏低，错位断带式螺带桨叶结构的混合效果更佳；错位断带式螺带桨叶结构能够增强颗粒的对流过程，能提升颗粒的混合效果；增加错位距离对混合效果没有明显的影响；当错位高度为30、 60、 90 mm时，在混合时间为7、 7、 8 s时就全部达到颗粒的完全混合；当螺距比为1时，混合效果最好。     

工艺参数对绝热层胶料分散效果的影响

利用双行星动力混合机,针对添加不同功能填料的绝热层胶料,通过设计搅拌速度、分散速度、分散时间等参数,确定出了高固含量有机硅绝热层胶料(基体+颗粒填料+抗剪切纤维)达到理想混合状态的最佳参数值。指出了双行星动力混合机在混合含易碎纤维胶料方面所存在的问题。     

三维运动混合机的性能及其影响因素

结合工作实际对三维运动混合机的性能及其影响因素进行浅析,首先基于混合原理对当前混合机的应用进行阐述,并提出相应的实验内容和实验方法,通过对比实验、物料实验和混合度实验对混合机进行性能测试,最后根据实验结果对影响混合机性能的相关因素进行探讨和分析。     

双螺杆粉体混合机混合均匀性的三维模拟与评价

建立一种连续化啮合反向旋转双螺杆物料混合机三维模拟模型,利用混合机出口处颗粒体积分数的相对标准偏差作为混合均匀性评价指标,建立螺杆转速与相对标准偏差的关系式,并阐述颗粒混合过程机理,为实现粉体混合均匀性的实时检测、评价与控制提供了理论基础。结果表明:在不同转速条件下,在混合工作区混合粉体均匀性沿螺杆轴向离进口距离增大而增大;随着螺杆转速增加,粉体出口处的相对标准偏差减小,混合粉体停留时间方差δ~2减小;混合粉体在矩形出口的均匀性随螺杆转速增大而增强;当螺杆转速由400 r/min增至800 r/min,出口处的相对标准偏差由48.08%减少至5.34%,相对标准偏差减幅高达89%,粉体混合均匀性大幅提高;粉体出口处相对标准偏差随混合时间增加而趋于减小,增加混合时间有利于提高粉体混合的均匀性。     

强剪切混合机

基于市场的需要。Hosokawa公司在1g96年开始着手开发新的具有革命性的高剪切混合机CyclIomix，使其同市场上其它高剪切混合技术相比具有无与比拟的特性。Cyclomix混合机的混合原理是基于将一个高剪切力和强冲击力的有效组合。     

三质体声共振混合机的动力学特性及其性能分析

为研究三质体声共振混合机的动力学特性,建立了三质体声共振混合机的动力学模型,进而分析了系统物理参数对动力学特性的影响,阐明了物料质量和阻尼变化对声共振混合机动力学响应的影响规律,提出了系统在共振频率附近工作的振幅控制策略。进一步分析了典型声共振混合机在额定载荷下的对地动载荷和所需激振力,并与额定载荷所需的最大推力进行了比较。结果表明,通过选择合理的系统物理参数,三质体声共振混合机在三阶共振频率附近工作,其振幅变化较平缓、负载质体和激振质体的运动相位相反,系统能够兼具能量转换率高、对地动载荷小且激振力小等优点。所得结论有助于进一步提高声共振混合机的工作性能和设计水平。     

散射角对相关光谱法纳米颗粒测量的影响

研究散射角对相关光谱法纳米颗粒测量的影响,对相关光谱法纳米颗粒实验系统进行改造,实现不同的散射角下纳米颗粒的相关光谱法测量.实验采用30 nm和200 nm的混合颗粒群,按不同比例进行混合,在90°和165°散射角对混合颗粒群进行测量,并对此实验结果进行了理论分析,结果表明,在对单一颗粒群进行测量时,在两个角度都能实现颗粒的准确测量,而在混合颗粒群测量时,测量结果受两种颗粒群混合比影响,而165°散射角具有更好的测量结果,因此在对混合纳米颗粒群进行测量时,采用大的散射角有助于颗粒的反演.     

常州天马粉体科技有限公司

<正>产品名称:WZ系列无重力双轴桨叶混合机产品简介:本系列混合机以强烈、高效混合为特点、卧式筒体内两根搅拌等速反向旋转,上特殊布置的桨叶确保物料径向、环向、轴向三向运动,形成复合循环,在极短的时间内达到均匀混合。产品特点:混合精度高,速度快,能耗低,可密封操作。气动、电动、手动出料方式。筒盖上可布置雾化装置以实现固液混合。应用范围:化学药品、洗涤剂、涂料、树脂、玻璃硅、颜料、农药、化肥、     

气相燃烧合成二氧化钛纳米颗粒

建立了CO气相燃烧合成纳米颗粒材料技术 ,利用TiCl4 气相氧化合成粒度小于 10 0nm纯金红石或锐钛和金红石混合相的TiO2 颗粒。混合温度升高、TiCl4 进料量减小、停留时间缩短时 ,二氧化钛颗粒粒度减小。随混合温度升高、TiCl4 进料增大以及停留时间延长 ,TiO2 颗粒中金红石含量增大。在反应物中加入AlCl3 作为晶型调节剂时 ,金红石含量增大。     

Modeling of dynamic microstructure evolution of EN AW-6082 alloy during hot forward extrusion

The aim of this work is to present briefly a model for predicting and simulating the evolution of microstructure, in particular the evolution of grains, during hot forming processes of aluminum alloy EN AW-6082 and give a comparison with the experimental results. The model is a physically motivated phenomenological model based on internal state dependent variables. The microstructure evolution is a temperature dependent process and is simulated in a fully coupled thermo-mechanical process by help of Finite Element software Abaqus. The results are compared and verified with experimental results obtained by EBSD measurement of a small-scale extrusion process established for scientific purposes. The simulation results are in reasonable agreement with experiment.     

Axial wave propagation in membrane shells of revolution

The dynamic finite element technique, which is referred to in the literature as ‘computer-analysis’, is applied to wave propagation problems occurring in finite and semi-infinite linearly elastic membranes of revolution. Both semi-infinite and finite versions of cylindrical and conical membranes are considered, and a finite membrane having a meridional curve which is parabolic is solved. The source of excitation is generally a constant velocity motion of one end of the membranes, but the results for a stress-pulse input at one end of a semi-infinite cylindrical membrane are also given. The results for the finite membranes are new, and the results for the semi-infinite problems are discussed with respect to previously published results. The two-dimensional state of stress in the membrane requires careful ordering of the calculations, and the boundary conditions for finite membranes are shown to follow logically from this ordering of the calculations. The difference in the solutions resulting from prescribing an axial or a tangential velocity excitation at the end of a conical membrane is presented, and the mesh size necessary for convergence to the solution is indicated. The graphs of the results clearly indicate regions in space and time where the membrane model should be replaced by the shell formulation to represent a realistic structure. The technique is shown to be self-contained and independent of any formal method such as the method of characteristics.     

真空预冷中捕水器的理论研究

真空预冷装置中,捕水器是一个十分关键的部件.其性能的优劣,直接关系到预冷的效果.介绍了捕水器的内部结构和捕水特性,建立了物理模型,对水蒸气在捕水器管路凝结问题进行了理论计算.最后对理论结果进行分析.     

钢管混凝土哑铃形偏压构件试验研究

进行了8 根钢管混凝土哑铃形短柱的偏压试验。试验参数为偏心率。试验结果表明,钢管混凝土哑铃形偏压短柱受力性能与单圆钢管混凝土偏压柱的有相似之处。对极限承载力的计算表明,现有的折算面积法偏于保守而格构式算法又偏于不安全。提出的修正的格构式算法与试验结果吻合良好且偏于安全,可供工程应用参考。     

Material law parameter determination of magnesium alloys

The deformation mechanisms of magnesium are investigated in order to obtain results for a better understanding of texture evolution and anisotropic behavior of magnesium wrought alloys. However, the insight into hcp plasticity is restrained by the fact that the deformation of hcp materials consists of three or more deformation modes, which complicates micromechanical modelling. In this paper it is demonstrated in case of magnesium alloys that an inverse parameter calculation of plasticity parameters can be significantly improved by a simulation strategy which is based on an appropriately chosen set of experiments. Room temperature deformation tests were performed on the magnesium model system AZ31. The results were simulated by using a viscoplastic self-consistent model. It is concluded that the results of rolled sheets are not sufficient, by contrast the results of extruded bars are a firm basis for model calculations. The results indicate that the initial textures must favor all relevant deformation modes.     

Unsteady MHD convective heat and mass transfer past a semi-infinite vertical permeable moving plate with heat absorption

The problem of unsteady, two-dimensional, laminar, boundary-layer flow of a viscous, incompressible, electrically conducting and heat-absorbing fluid along a semi-infinite vertical permeable moving plate in the presence of a uniform transverse magnetic field and thermal and concentration buoyancy effects is considered. The plate is assumed to move with a constant velocity in the direction of fluid flow while the free stream velocity is assumed to follow the exponentially increasing small perturbation law. Time-dependent wall suction is assumed to occur at the permeable surface. The dimensionless governing equations for this investigation are solved analytically using two-term harmonic and non-harmonic functions. The obtained analytical results reduce to previously published results on a special case of the problem. Numerical evaluation of the analytical results is performed and some graphical results for the velocity, temperature and concentration profiles within the boundary layer and tabulated results for the skin-friction coefficient, Nusselt number and the Sherwood number are presented and discussed.     

受静压力作用加筋板隔声性能研究

基于随机平面波声源建立混响声源激励的加筋板隔声计算模型,通过对试验模型数值计算,二者结果基本吻合;计算存在静压力时加筋板隔声特性表明,存在静压力时加筋板基频移动会致低频隔声量显著增加,压力增加到一定程度时隔声量基本不再增加;此刻为存在预应力的实际结构物隔声量计算提供参考。     

表面粘贴光纤干涉仪测量复合材料梁的分层

从理论上和实验中分别讨论了将光纤干涉仪的传感臂粘贴在梁的表面时，在简单支撑和弹性连续支撑条件下，通过检测光纤(即梁的表面)的形变，检测复合材料的分层，理论分析和实验都表明，在连续支撑下，可以测量出分层的存在，在有分层的地方，干涉仪的输出会反向，在简单支撑下，不能测出是否存在分层，因为材料本身的变形对粘贴在表面的光纤的影响远远大于分层的影响，这一技术也适用于复合材料修补后的脱层检测。     

The effect of crack surface interaction on the stress intensity factor in Mode III crack growth in round shafts

Turbine-generator shafts are often subjected to a complex transient torsional loading. Such transient torques may initiate and propagate a circumferential crack in the shafts. Mode III crack growth in turbo-generator shafts often results in a fracture surface morphology resembling a factory roof. The interaction of the mutual fracture surfaces results in a pressure and a frictional stress field between fracture surfaces when the shaft is subjected to torsion. This interaction reduces the effective Mode III stress intensity factor.The effective stress intensity factor in circumferentially cracked round shafts is evaluated for a wide range of applied torsional loading by considering a pressure distribution between mating fracture surfaces. The pressure between fracture surfaces results from climbing of asperities respect to each other. The pressure profile not only depends on the fracture surface roughness (height and width (wavelength) of the peak and valleys), but also depends on the magnitude of the applied Mode III stress intensity factor. The results show that asperity interactions significantly reduce the effective Mode III stress intensity factor. However, the interactions diminish beyond a critical applied Mode III stress intensity factor. The critical stress intensity factor depends on the asperities height and wavelength. The results of these analyses are used to find the effective stress intensity factor in various Mode III fatigue crack growth experiments. The results show that Mode III crack growth rate is related to the effective stress intensity factor in a form of the Paris law.     

混凝土浇筑期高大模板支撑体系的受力性能研究

为了掌握混凝土浇筑期高大模板支撑体系的受力性能,实地搭建8m高扣件式模板支架进行试验。通过吊装钢渣加载的方式模拟混凝土浇筑过程,测试模板下立杆轴力变化进行,给出了荷载施加顺序和支架受力的关系;提出了有限元建模方法对浇筑期支撑体系的工作状态进行模拟,通过对比发现本文提出的方法可以较为有效地计算立杆受力;将试验结果与现行规范计算结果进行对比,发现了现行规范存在的不足。