Effects of dissipative forces on Coriolis flowmeter readings

An indirect measurement method based on recording the phase difference of resonance vibrations of two symmetrical halves of the flow-carrying tube is used to quantify the mass flow rate of the current fluid in Coriolis mass flowmeters (CMFs). A variant of modeling the CMF vibration system is analyzed, which allows taking into account the influence of the dissipation of oscillations of a measuring tube with fluid flowing through it on the dependence between the mass flow rate of the fluid and the phase difference recorded by the sensor. The steady-state CMF vibration mode is considered as the result of the superposition of two principal vibrations of the measuring tube. The first principal coordinate corresponds to the deformation of the measuring tube along the lowest natural mode excited by an external driving force in the resonance mode. Vibrations of the other principal coordinate correspond to deformation in a natural mode corresponding to a higher natural frequency than the frequency of the exciting force. The relationship of the amplitudes of the principal coordinates is established on the basis of the gyroscopic coupling of the principal vibrations that occurs when a fluid flows through a tube. The coefficients of gyroscopic coupling are determined as a result of 3D finite-element simulation of the steady-state vibration mode of the measuring tube with a flowing fluid. The simulation is performed for five variants of the shape of the axis of the measuring tube, taking into account the distribution of the gyroscopic forces of the flowing fluid. Quantitative estimates of the influence of dissipative forces on the flowmeter readings are obtained on the example of dissipative forces of linear viscous friction. A comparison of the CMF simulation results for different tube axis shapes demonstrates how the phase shift arising in the vibration system is affected by the dissipation level and the proximity of the natural frequencies of the flowmeter measuring tube at a fixed mass flow rate of the fluid.     

基于自组装成品率的球栅阵列焊点工艺参数分析

为了提高球栅阵列焊点封装器件的自组装成品率,研究了焊点体积偏差率及焊盘直径对器件自组装成品率的影响。考虑封装器件的温度翘曲变形、焊点体积的不可避免的制造误差及焊点位置的随机性,分析了器件自组装过程。通过求解不同体积焊点的形态,得到了不同体积焊点的液桥刚度曲线。基于不同体积焊点的液桥刚度曲线,仿真分析了焊点体积偏差率及焊盘直径对器件自组装成品率的影响。结果表明,焊点体积偏差率及焊盘直径的减小会增大焊点液桥刚度曲线的公共范围,从而提高器件的自组装成品率。     

韧性材料的几种断裂形式及判据讨论

考察几种韧性材料的复合型断裂试验过程，用传统强度理论思想认定启裂位置与启裂方向，通过对不同物理机制的断裂形式变化规律的研究，判定韧性材料的主要断裂形式有三类，以空穴成核、扩张、聚合为主导机制的正拉断，和以局部剪切带形成、发展为主导机制的两种不同类型的剪切断裂。局部大塑性变形的出现在材料内引起损伤，空穴的聚合或局部剪切带的出现仅发生在载荷达到某一临界值时。导致材料断裂发生的根本因素，是危险点上某应力参数达到了材料的断裂临界值，以此对不同断裂形式的断裂判据进行讨论，提出新的韧性断裂判据。     

高速动车组减振器载荷特征研究

减振器的主要功能是提供阻尼力以衰减和抑制车辆系统振动,对高速动车组动力性能有十分重要的影响。既有研究主要将减振器处理为阻尼力以研究车辆系统动力性能,极少从动力学和结构可靠性角度关注减振器自身承受的载荷。制作某型高速动车组转向架抗蛇行减振器、轴箱减振器、二系横向和垂向减振器测力元件,在大同-西安高速线路上测试并获得该型动车组运行过程中四种减振器载荷引起的应变信号。对测试数据进行处理和分析,获得高速动车组运行工况下四种减振器载荷的时间历程,分析减振器载荷的时域和频域特征。采用雨流计数法统计减振器载荷峰谷值和频次,获得不同速度等级下载荷分布。结果表明,高速动车组抗蛇行减振器载荷最大、二系横向减振器载荷最小。轴箱减振器相对速度最大、二系横向减振器相对速度最小。减振器载荷总体上呈正态分布,而且一般有列车运行速度越高减振器载荷越大。列车正线行驶时曲线半径对轴箱减振器、二系垂向减振器以及二系横向减振器载荷影响不明显,列车速度和线路小半径曲线对抗蛇行减振器载荷影响明显。     

The dynamic stability of a crane standing on soil during the rotation of the boom

In this work the influence of flexible soil foundation on the dynamic stability of the boom crane is presented. This analysis was made during the rotation of the boom, such that variable pressure on the soil and other deformations could be taken into account. The rheological deformation of the soil as a function of the changing strain in time has been described by an equation, which is the Duhamel integral. After accepting the discrete model of the considered system dynamic equations of motion were elaborated, which because of their nonlinearity and complexity were solved numerically. Appointed were the dynamic displacements of each of the supports for different rotational speeds of the boom, showing the influence of the rheological deformation of the soil on the behaviour of the whole crane. As well the trajectories of the motion of the weight hoisted were presented for different rotational speeds of the boom, which enabled the analysis of the precision of the positioning of the weight being hoisted (minimization of oscillation).     

可变节流高度气浮支承结构设计及静态性能分析

为研究节流高度的变化对气浮支承性能的影响,设计一种可变节流高度的气浮支承。建立气浮支承CFD模型,分析节流口直径、节流高度、均压腔深度和供气压力的变化对气浮支承静态性能的影响。研究结果表明:气浮支承的承载能力随节流口直径、节流高度、均压腔深度和供气压力增大而增大;节流高度、均压腔深度、供气压力的增大能提高气浮支承刚度,而节流口直径的增大会导致刚度的降低;气浮支承的体积流量随节流口直径、节流高度、均压腔深度和供气压力增大而增大。     

大袋包装机抱袋装置建模与运动学分析

为解决包装机抱袋装置运动过程中产生机械振动及减小末端执行构件冲击的问题,首先根据运动要求建立机构模型,通过对装置运动中约束条件进行分析,得到摆臂转轴处角位移、角速度及角加速度,以及摆臂末端位移、速度及加速度的数学表达式。其次对数值计算与运动算例分析,以摆臂转轴处角加速度与末端加速度峰值为优化目标,对机构结构参数进行优化。结果表明:通过改变机构结构参数可以降低摆臂转轴处与末端加速度峰值,装置运动过程中摆臂转轴处角加速度峰值降低25.89%,抱袋口末端加速度峰值降低20.46%,抱袋身末端加速度峰值降低24.87%,在一定程度提高运动平稳性。相关结论可为后续动力学分析与设计提供理论依据。     

大功率轮胎式装载机的液压传动系统研究

通过对装载机静压传动和动压传动两种传动方式的比较 ,分析了静压传动系统相对于采用液力机械的动压传动的一些优点 ,指出装载机发展现状及开始向高技术、大型化、采用静压传动的趋势。在分析装载机大型化和采用静压传动存在的问题的基础上 ,提出了大功率轮胎式装载机的静压传动方案。     

GB15563《震源药柱》2006版修订内容

新标准GB15563-2006《震源药柱》在95版基础上有较大变化,扩大了适用范围;根据目前震源药柱的生产和使用情况,对震源药柱进行了重新分类;对部分产品性能指标的要求进行了调整;对震源药柱壳体颜色重新进行了规定;补充完善了爆速测试方法;增加了抗水性能和抗拉性能试验装置示意图;对震源药柱的编码方式进行了统一规定;对检验项目和抽样方案进行了调整;增加了包装检验的内容[3]。     

Laser vibrodiagnostics of nonhomogeneous materials

The influence of nonhomogeneous material areas on the natural frequencies and interference pattern of vibrations of thin plates is analyzed by the speckle pattern and the holographic interferometry methods and the results are discussed. The dependence of the natural frequency bias and the vibration amplitude of the plate on the location of the nonhomogeneity has been researched taking into account excitation of the higher modes of vibration. It is shown that the natural vibration bias was maximum if the center of nonhomogeneity was located at the amplitude maximum of the vibrating plate. The sign of the frequency bias characterizes the prevailing influence of the relative change of density or rigidity of the plate. As shown from iterferograms obtained by the time-average holographic method the influence of heating with an infrared laser beam led to distortion of the interference pattern, which bears witness to the change of vibration form of the plate and the appearance of new amplitude maxima. The vibrations of nonhomogeneous areas have been examined by holographic interference microscopy.     

空基红外系统作用距离建模及应用分析

针对现有红外系统作用距离模型影响因素考虑较少、难以准确评估系统探测能力及目标红外隐身效果的问题,开展空基红外系统作用距离建模及应用案例分析。分析典型红外系统作用距离的影响因素,定义大气光谱透过率与作用距离的隐函数,基于大气垂直高度层上温度差异明晰光谱辐射强度分布模型,考虑目标红外光谱辐射线型特征推导大气透过率加权修正系数,进而构建了综合目标光谱辐射特性、大气温度和红外系统高度等多种因素的空基红外系统对点目标作用距离模型。基于该模型,对不同类型空基红外系统的探测能力及不同类型目标的红外隐身性能进行了比较和分析。结果表明,对于导弹、飞机类目标,采用大口径、长波段系统设计有利于提升空基红外系统对目标迎头方向探测能力,大口径中波红外系统对目标尾后方向探测能力更强;小尺寸、低表面发射率、低速飞行目标的红外隐身及突防能力更好,目标在平流层飞行时隐身性能要优于对流层和中间层飞行目标。     

干燥带对绝缘子温度场影响的研究

对干燥带对污秽绝缘子温度场分布进行了研究,介绍了绝缘子干燥带形成原因,利用绘图软件,绘制了绝缘子分析模型; 然后分析了干燥带的产生过程; 最后运用ANSYS软件电热耦合的方法,从干燥带产生位置、干燥带产生条数、干燥带产生长度、干燥带产生宽度4个方面,分析污秽绝缘子径向温度分布情况。研究结果表明,干燥带产生位置、干燥带产生长度、干燥带产生宽度、干燥带产生条数不同,绝缘子径向温度分布特征差异较大。     

晶须长径比对树脂基复合材料力学行为影响的数值模拟

在单向晶须增强树脂基复合材料的轴对称模型和已有研究成果基础上,利用有限元分析方法,研究该类复合材料中晶须长径比的变化对材料整体力学行为的影响.结果表明:晶须长径比对晶须应力作用明显大于对基体的影响;晶须的长径比h/r≤30时,随着晶须长径比的增大,发生在晶须端部处的集中应力急剧增加;但当长径比h/r＞30时,长径比的进一步增加对集中应力影响不大;随着晶须长径比的增大,界面剪切应力减小,分布曲线下移;但当长径比h/r＞30时,长径比的进一步增加对剪切应力影响不大;随着晶须长径比的增加,复合材料的拉伸强度逐渐增大.     

Effects of design parameters on the noise of rotor-bearing systems

The purpose of the present paper is to investigate the effects of design parameters on the noise produced by rotor-bearing systems supported by oil lubricated journal bearings. To do this, the effects of radial clearance and the width of the bearing, lubricant viscosity, and mass eccentricity of the rotor on the noise of the bearing are investigated, and the numerical results are presented through the graph of the A-weighted sound pressure level of the bearing for various rotational speeds of the rotor. The results show that the A-weighted sound pressure level of the bearing is markedly influenced by the mass eccentricity of the rotor and the radial clearance and the width of the bearing. High viscosity of the lubricant slightly decreases the noise of the bearing, but its effect is relatively low at high speed. The results of the paper could aid in the design of low-noise rotor-bearing systems supported by oil lubricated journal bearings.     

Research of the mechanism and development of the wear model of a diamond tool when turning aluminum-matrix composite materials

The results of a study of the wear mechanism of diamond tools for turning aluminum-matrix composite materials (ACMs) hardened by Al₂O₃, SiC, and B₄C particles are presented. The study of the posterior surface topography of a diamond tool (ASPK-2) shows the presence of parallel scratches in the direction of the vector of the cutting speed; it is characteristic of abrasive wear fatigue. Research on the mass-transfer of the elements of the tool material into the chips of the treated material is carried out; it shows the presence of particles of the tool material of a size comparable to the ACM filler microparticles. The model of the abrasive-wear fatigue of a diamond tool during the turning of ACMs, considering the power of the impact of the reinforcement particles, the hardness of the tool depending on the temperature in the cutting zone, the abrasiveness, and the mass fraction of the dispersed particles reinforcing the matrix and tool geometry is proposed.     

覆膜铁熔融覆膜过程界面传热与熔膜填充行为研究

覆膜铁是金属包装领域的新型复合材料。成品覆膜铁的界面结合强度和水透性取决于覆膜过程中高聚物薄膜熔融层的厚度和流动铺展行为。但覆膜过程复杂而迅速，且受钢板表面微观形貌影响，熔融层膜厚及其流动铺展行为难以精细调控。针对此，基于分形理论表征与重构基板带钢表面微观形貌；基于广义Maxwell模型试验建立聚合物膜的黏弹性本构关系；建立了考虑基板带钢表面微观形貌的覆膜过程有限元仿真模型，并试验验证了模型的准确性。研究表明，熔融层膜厚主要受基板带钢初始预热温度影响，界面填充率则主要受覆膜辊压力影响。高聚物膜熔融层厚度和界面填充率随基板带钢粗糙度降低以及基板带钢和覆膜辊初始预热温度增加而增加，且辊压力增加也导致界面填充率增加。这些规律被定量化描述，为精细化调控熔融层膜厚及其流动铺展行为提供了理论依据。     

Effect of the Error in Determination of Pipeline Parameters on Characteristics of a Gamma-Absorption Densimeter of a Transported Binary Mixture

Mathematical relations which make it possible to estimate the effect of errors in determination of pipeline parameters on the error in measurements of the density of a binary mixture with reference to a cement mortar is considered. The results of calculations of the mass radiation attenuation coefficients as functions of the gamma-quantum energy are given for main components of the tested object with allowance for variation of the cement formula. On the basis of the data and formulas obtained, which establish requirements for the recorded signal of a densimeter, the presence of optimum ranges of the gamma-quantum energies of the source and a significant in uence on the signal and the necessity to take the multiplicative component of the instrumental error of the densimeter into account are demonstrated. Recommendations on the choice and calculation of particular parameters and optimization conditions of the densimeter are given with reference to the formulated problem of testing.     

A Noise Analysis of Cylindrical Roller Bearings Operating Under Zero External Load

The purpose of this article is to numerically investigate one source of acoustic noise in roller bearings, that which results from the motion of the rollers in the bearing under zero external load. For the sake of simplification, it was assumed that the cylindrical roller bearings are infinitely long. Furthermore, the effects of the following on the noise of the bearing were also examined: the radial clearance of the bearing, the viscosity of the lubricant, and the number of rollers. The results of the study show that the fundamental frequency of the noise components of the cylindrical roller bearing corresponds to the multiplication of the number of rollers and the whirling frequency of the roller center. The acoustical frequency spectra of the cylindrical roller bearing are pure tone spectra, containing the fundamental frequency of the roller bearing and its superharmonics. The factors that decrease the sound pressure level of a cylindrical roller bearing include low lubricant viscosity, high radial clearance, and a reduced number of rollers. The results and discussions of the present article could aid in the design of low-noise cylindrical roller bearings.     

电比例斜盘式恒压柱塞泵的联合仿真与特性研究

为了研究电比例斜盘式恒压柱塞泵的动静态特性，在分析其工作原理、运动特性和流量特性的基础上，利用SimulationX软件搭建恒压泵的机械、液压联合仿真模型进行研究，分析了变量缸大小腔直径比、变量缸弹簧刚度和主控压力阀的阀芯直径对恒压泵动态特性的影响。研究结果表明：电比例斜盘式恒压柱塞泵泵具有良好的动静态特性；主控压力阀阀芯直径越大，压力稳态值越接近设定压力值；弹簧刚度的增大和变量缸大小腔直径比值的减小都会提高恒压泵的动态响应速度，但超调量也会随之增大。