Cavitation of a Submerged Jet at the Spherical Valve Plate/Cylinder Block Interface for Axial Piston Pump

The spherical valve plate/cylinder block pair has the advantages of strong overturning resistance and large bearing area.However,the configurations of the unloading and pre-boosting triangular grooves on the spherical valve plate are different from those in the planar valve plate,resulting in special cavitation phenomenon on the spherical port plate pair.In order to study cavitation characteristics of spherical port plate pair,a dynamic CFD model of the piston pump including turbulence model,cavitation model and fluid compressibility is established.A detailed UDF compilation scheme is provided for modelling of the micron-sized spherical oil film mesh,which makes up for the lack of research on the meshing of the spherical oil film.In this paper,using CFD simulation tools,from the perspectives of pressure field,velocity field and gas volume fraction change,a detailed analysis of the transient evolution of the submerged cavitation jet in a axial piston pump with spherical valve plate is carried out.The study indicates the movement direction of the cavitation cloud cluster through the cloud image and the velocity vector direction of the observation point.The sharp decrease of velocity and gas volume fraction indicates the collapse phenomenon of bubbles on the part wall surface.These discoveries verify the special erosion effect in case of the spherical valve plate/cylinder block pair.The submerged cavitation jet generated by the unloading triangular grooves distributed on the spherical valve plate not only cause denudation of the inner wall surface of the valve plate,but also cause strong impact and denudation on the lower surface of the cylinder body.Finally,the direction of the unloading triangular groove was modified to extend the distance between it and the wall surface which can effectively alleviate the erosion effect.

MECHANICAL ANALYSIS OF CYLINDERS BEING UPSET BETWEEN SPHERICAL CONCAVE PLATEN AND CONCAVE SUPPORTING PLATE

Mechanical analysis of cylinders being upset between spherical concave platen and concave supporting plate is conducted. Rigid-plastic mechanical models for cylinders are presented. When the ratio of height to diameter, is larger than 1, there exists two-dimensional tensile stress in the deformed body, when the ratio is smaller than 1, there exists shear stress in static hydraulic zone. The former breaks through the theory that there is three-dimensional compressive stress irrespective of any ratio of height to diameter. The latter satisfactorily explains the mechanism of layer-like cracks in disk-shaped forgings and the flanges of forged gear axles. The representation of the two models makes the upsetting, theory into correct and perfect stage.

VIBRATION AND ACOUSTIC RADIATION FROM SUBMERGED STIFFENED SPHERICAL SHELL WITH DECK-TYPE INTERNAL PLATE

Based on the motion differential equations of vibration and acoustic coupling system for thin elastic spherical shell with an elastic plate attached to its internal surface,in which Dirac-δ functions are employed to introduce the moments and forces applied by the attachment on the surface of shell,by means of expanding field quantities as Legendre series,a semi-analytic solution is derived for the vibration and acoustic radiation from a submerged stiffened spherical shell with a deck-type internal plate,which has a satisfactory computational effectiveness and precision for an arbitrary frequency range.It is easy to analyze the effect of the internal plate on the acoustic radiation field by using the formulas obtained by the method proposed.It is concluded that the internal plate can significantly change the mechanical and acoustic characteristics of shell,and give the coupling system a very rich resonance frequency spectrum.Moreover,the method can be used to study the acoustic radiation mechanism in similar structures as the one studied here.

Analysis of Error Caused by Replacing Spherical Shell with an Elastic Plate Model in Studying Bending Deformation of the Lithosphere

To study the bending deformation of the lithosphere, the simplification of replacing a spherical shell by a plate model is usually made. Based on the differential equations for the bending of plates and shallow spherical shells, an expression for the error caused by such a simplification is derived in this paper. The effect of model sizes on the error is discussed. It is proved that if we replace the shallow spherical shell by a plate model to solve the bending deformation of lithospheric plate, a large error will be caused. In contrast, if we use a plate on an elastic foundation instead, an approximate solution closer to that of spherical shell can be obtained. In such a way, the error can be reduced effectively and the actual geological condition can be modeled more closely.

单板焊接空心球节点受拉承载性能研究

单板焊接空心球节点常用做弦支穹顶上部结构连接拉杆或拉索的节点,单板主要承受拉力并传递至焊接空心球,为了满足工程设计的要求,需对其受拉承载性能进行研究.通过试验,研究了不同参数的单板焊接空心球节点轴拉状态下的受力性能和破坏机理,建立有限元模型并进行验证,该模型能较好地反映单板焊接空心球节点轴拉性能,通过有限元模型参数化分析揭示了节点尺寸、加劲肋、单板尺寸等参数对其力学性能的影响规律,并提出单板焊接空心球轴拉承载力计算公式.研究结果表明:单板焊接空心球在轴拉作用下为应力集中导致的剪切强度破坏,破坏发生在单板端部与空心球连接处,表现为焊接空心球被撕裂;有限元应力云图得出破坏时沿着单板平面内拉力方向的剪应力起主要作用;单板焊接空心球节点的受拉承载力随单板宽度及空心球壁厚的增大而明显增大,空心球直径的增大会使承载力略有降低,单板的厚度增加使节点承载力略有提高,单板的高度对节点承载力的影响较小,空心球内设置加劲肋能使承载力提高至少20%;基于参数化提出的单板焊接空心球节点的受拉承载力计算公式能简便地计算出单板焊接空心球节点的承载力,相对误差在±15%以内,满足工程设计误差要求.研究工作可为今后外接单板的焊接空心球节点分析设计提供参考.

复合材料双层球壳与环板耦合结构振动特性研究

以一阶剪切变形理论为基础,采用谱几何法对不同边界条件下复合材料双层球壳与环板耦合结构振动特性分析模型进行构建,其中采用人工虚拟弹簧技术模拟耦合结构的边界条件。根据耦合处的连接关系,通过布置耦合弹簧模拟器对子结构之间的耦合关系进行模拟。应用哈密顿原理对复合材料双层球壳与环板耦合结构的特征方程进行推导,对耦合结构的固有特性和稳态响应进行求解。将所得结果与有限元结果进行对比,验证了计算的正确性。分析了几何参数、材料参数对复合材料双层球壳与环板耦合结构振动响应的影响。

双耳板焊接空心球节点轴拉力学性能研究

目的探究双耳板焊接空心球节点的受拉力学特性,揭示破坏机理并探讨影响其承载力的主要因素。方法针对8个双耳板焊接空心球节点进行轴心受拉极限承载力试验,并采用ABAQUS有限元分析软件对节点进行参数化数值分析,重点讨论节点几何尺寸对其承载力的影响。结果在轴向拉力作用下,双耳板焊接空心球节点破坏形式分为空心球开裂破坏,耳板与空心球连接处焊缝失效,且个别试件出现球面局部起皮;空心球与耳板连接端部处应力集中明显,随着荷载增大,在空心球与耳板连接处沿径向逐步进入屈服阶段。结论节点轴拉极限承载力,与空心球直径、耳板宽度与球外径比、耳板厚度与球壁厚度比呈正相关,与空心球径厚比呈负相关,且上述影响因素中空心球壁厚与耳板厚度比对承载力影响相对较小。

柱塞倾斜分布式球面配流重载柱塞泵泄漏特性

倾斜柱塞结构和球面配流副因结构紧凑、抗倾覆力矩强等优点广泛应用于重载柱塞泵,随着工程技术的发展及高端制造业需求,柱塞泵的使用压力逐渐提高,油液泄漏加剧,设计间隙和容积效率成为评价柱塞泵性能好坏的重要指标。以倾斜柱塞和球面配流结构的重载柱塞泵为研究对象,分析柱塞的运动学特性,研究倾斜柱塞副泄漏、球面配流副泄漏和滑靴副泄漏的理论方程。结果表明,倾斜柱塞副的泄漏随配合间隙及柱塞腔压差增大而增大,球面配流副泄漏间隙主要与动力黏度、泵工作压力及缸体角速度相关,滑靴副的泄漏主要和柱塞阻尼孔长度和阻尼孔直径相关。最终,通过泄漏试验验证了理论结果的准确性,理论值与实验值误差不超过8%,为重载柱塞泵的结构设计与性能优化提供理论基础。

环口板加强带脱空缺陷的钢管混凝土T型节点滞回性能试验研究

为研究环口板加强带脱空缺陷的钢管混凝土T型节点的抗震性能,完成了12根节点试件在主管受恒定轴拉力与支管受轴向往复荷载作用下的滞回试验,基于试件破坏模式、荷载-位移滞回关系和应变发展考察了采用环口板加强带脱空缺陷T型节点试件的效果,并对比分析支主管直径比和主管径厚比对试件加强效果的影响。试验结果表明:采用环口板加强T型节点有效抑制了脱空缺陷导致的主管塑性变形,并实现带缺陷T型节点承载力、刚度、延性和耗能能力的完全恢复,甚至优于相应的无脱空试件,其中加强试件的承载力较带脱空缺陷试件提升12.6%以上,较无脱空试件提升6.5%以上,表明经合理设计的环口板加强措施能够弥补脱空缺陷对节点抗震性能的不利影响。

既有网架受拉球节点托板加固技术试验研究

针对既有网架结构下弦受拉球节点加固问题,提出一种基于临杆焊接托板的加固方法。该方法综合考虑了受拉球节点与杆件的材质、空间结构以及尺度效应的影响,通过将球节点周围相邻杆件焊接托板进行加固,使得该方法便于施工,且能够普遍适用于各类受拉球节点的加固工程,并通过模型试验验证和仿真研究,焊接托板后的节点域承载能力大幅提升,加固效果良好,为既有网架受拉球节点加固提供了新思路。

大型球罐板块冲压成形仿真分析及数据库建立

基于ABAQUS有限元仿真软件,对3000m^(2)大型球罐板块冲压成形工艺进行了研究,结合实验验证,分析了板块成形质量的影响因素,基于冲压力参数设置需求,研究不同工况的板块使用不同压力进行冲压时的变形量,得出不同工况的板块被不同压力冲压时的变形规律基本一致,板块变形量随冲压力的增大而增大,且板料的初始变形越大,相同冲压力变形越小,变形越困难。基于仿真工艺参数及变形等结果,建立了球壳板冲压工艺数据库,对提高球罐板块的冲压效率及工艺参数优选具有指导意义。

既有网架受拉球节点托板加固技术试验研究

针对既有网架结构下弦受拉球节点加固问题,提出一种基于临杆焊接托板的加固方法。该方法综合考虑了受拉球节点与杆件的材质、空间结构以及尺度效应的影响,通过将球节点周围相邻杆件焊接托板进行加固,使得该方法便于施工,且能够普遍适用于各类受拉球节点的加固工程,并通过模型试验验证和仿真研究,焊接托板后的节点域承载能力大幅提升,加固效果良好,为既有网架受拉球节点加固提供了新思路。

桥梁转体施工转动体系中球铰结构中间耐磨板的优化设计

球铰结构作为桥梁转体施工中的核心部件,其性能决定了转体过程的成败。很多相关研究简化球铰模型,仅考虑上下钢制球面板作为摩擦副而忽略中间耐磨板,因此有必要开展针对中间耐磨板的力学性能研究和参数优化设计。依托于贵州省某座T构转体,利用Abaqus软件建立并验证球铰部位有限元模型。基于粒子群优化算法(PSO),以滑板间距和滑板厚度为设计变量,接触面摩阻力分布均匀程度为优化目标,构建了耐磨板尺寸参数优化模型。同时利用Python语言对Abaqus进行二次开发,实现了有限元求解和参数优化的自动化。研究结果表明:原有耐磨板的接触压力呈现“中间低”和“边缘高”的分布规律,不利于充分利用材料性能和工程简化计算。优化后的球铰耐磨板最大接触应力由37.64 MPa减小到25.57 MPa,接触面积缩减了50.5%,应力均方差由4.47降低至0.85,接触界面应力分布更加均匀。该研究可为球铰接触面优化设计提供理论依据和技术支撑。

陶瓷平板膜在球形氧化铝提纯工序中的应用

针对四川某高新材料股份有限公司生产的高纯度球形氧化铝粉体,产品在烧球制备过程中需改变粒径的大小,烧球后的粉体具有较高的电导率和磁性,物料中还有一些杂质和金属残渣。提纯工序是产品的最后关键工序,工序采用“预处理筛分+陶瓷平板膜超滤”工艺。该工艺采用高温纯水与粉体混合成浆料,浆料与纯水混合摩擦置换出高电导率的废水,用陶瓷平板膜超滤工艺将浆料中的高电导率废水分离出来,达到提高球化率,降低电导率,去除杂质的效果。实机运行证明,陶瓷平板膜提纯处理能力为600kg/批次,每天8小时处理4个批次,120分钟/批次,过滤通量200~300L/m^(2)·h,出水稳定,浊度≤0.5 NTU,30~60天离线清洗一次;经过该工艺处理后的球形氧化铝粉体纯度≥99.9%,球化率96%~98%,pH范围7~8,电导率≤5μs/cm,其特征指标满足企业质量标准及优于GB/T24487-2022《氧化铝》标准中的化学成分和外观质量要求。

双耳板焊接空心球书点轴拉承载力研究

为揭示双耳板焊接空心球节点受拉破坏机理,并建立其受拉承载力计算公式。针对8个双耳板焊接空心球节点进行轴心受拉极限承载力试验,并采用ABAQUS有限元分析软件对节点进行参数化数值分析,讨论节点几何尺寸对其承载力的影响。研究结果表明,在轴向拉力作用下,双耳板焊接空心球节点破坏形式为空心球开裂破坏,耳板与空心球连接处焊缝失效,且个别试件出现球面局部起皮。提出了适用于球外径在160~500mm的双耳板焊接空心球节点的受拉承载力计算参考公式,研究成果可为类似工程设计提供参考。

Influence of graphite particle size and its shape on performance of carbon composite bipolar plate

Bipolar plates for proton exchange membrane fuel cell (PEMFC) where polymer is used as binder and graphite is used as electric filler were prepared by means of compression molding technology. Study on the effects of graphite particle size and shape on the bipolar plate performance, such as electrical conductivity, strength, etc. showed that with decrease of graphite particle size, bulk electrical conductivity and thermometric conductivity decreased, but that flexural strength was enhanced. After spherical graphite occurrence in flake-like form, the flexural strength of the bipolar plate was enhanced, electrical conductivity increased but thermal conductivity decreased in direction paralleling pressure direction, and both electrical conductivity and thermometric conductivity reduced in direction perpendicular to pressure direction.

FEA technique of hot plate forming process using cell-typed die with cooling device

Hot plate forming using a cell-typed die is a process for forming a large thick plate with a spherical shape for the manufacture of a large spherical LNG tank.Cell-typed upper and lower dies made of a framework of steel plates fitted to make a grid pattern are used in this process,and an air-cooling device is separately installed inside the lower die.A finite element analysis (FEA) technique was developed,which included hot forming,air flow,cooling and thermal deformation analysis for the hot plate forming process using the cell-typed die.Further,the convective and interface heat transfer coefficients were used to reproduce analytically the effects of the cooling device in the hot plate forming analysis.A small-scale model test of the process was conducted to verify the FEA technique.The analysis results show that the curvature of the final plate agrees well with that of the designed experiment within a maximum relative error of 0.03% at the corner of the plate.

多弧槽球面配流副润滑特性分析与多目标优化

为改善锥形缸体球面配流副油膜润滑特性,提出一种多弧槽球面配流副结构,并采用遗传算法对多弧槽球面配流结构进行多目标优化。首先,对多弧槽球面配流副进行理论建模,采用有限容积法对油膜压力控制方程进行离散化,利用环形三对角矩阵算法(CTDMA)求解球面配流副压力分布;然后,对多弧槽球面配流副承载特性进行仿真,分析球面配流副不同弧槽结构下的油膜厚度分布及压力分布规律;最后,以缸体倾角、泄漏量和摩擦转矩为优化目标,利用多目标遗传算法优化多弧槽球面配流副的结构参数。结果表明:多弧槽结构可提升球面配流副油膜承载能力,弧槽结构最小膜厚下降3.1%~4.0%,弧槽结构最大压力显著提高,最大增幅为16.3%;同时可有效降低泄漏量、摩擦转矩,优化后综合目标性能提升10.5%,缸体倾角、泄漏量和摩擦转矩分别下降5.1%、8.1%和5.9%,有效提升了球面配流副润滑性能。

多源石墨固废制备电热板材配方试验研究

为了提高石墨固废利用率,本文以石墨开采废石为细骨料,添加球形石墨尾料以及不同质量分数的废石石粉进行电热板材配方试验,探究了石墨开采废石取代量、石粉掺量对电热板材性能的影响。结果表明:在100%(质量分数)使用石墨开采废石作为细骨料时,养护28 d的水泥板材抗折强度及抗压强度分别达到11.09 MPa和50.90 MPa,虽然略低于使用标准砂的水泥板材的强度指标,但是仍可满足相关要求,说明石墨开采废石可以作为细骨料使用;在废石石粉掺量为7%(质量分数)时,电热板材的抗折强度和抗压强度最高分别达到6.21 MPa和33.00 MPa,虽然强度有所降低,但是仍可满足低强度板材的要求;在球形石墨尾料掺量为9%(质量分数)时,电热板材体积电阻率为1.94Ω·m,发热温度为71℃,具有良好的电热效果。

3000 m^(3)不锈钢复合板球罐的制造与安装

该3000 m^(3)球罐采用S30403+Q345R复合钢板制造,不锈钢复合板具有基层低合金钢和覆层不锈钢的综合特性,能体现其低成本和高性能的结合。对不锈钢复合板球壳板的压制成型、坡口切割、现场组装、焊接热处理、酸洗钝化等提出更高的要求,针对不锈钢复合板球罐制造与安装过程中关键控制点及存在的技术难点提出了有效解决措施。工程实例情况表明,球壳板三角形冷压法、合理的X形坡口形式、覆层无吊点组装工艺以及可靠的覆层焊接工艺,是提高不锈钢复合板球罐制造与安装质量的关键因素。