考虑非线性大变形的轮胎模态分析

轮胎的动态特性是影响包括操纵稳定性、行驶平顺性在内的车辆整体性能的重要指标之一。建立了考虑轮胎的实际边界条件、复杂材料特性的有限元模型，进行了考虑非线性大变形的模态分析。同时分析了影响模态频率的各个因素，主要包括轮胎胎压、轮胎侧壁材料和轮胎胎体质量。     

基于模态参数识别的悬架系统状态监测方法及试验研究

悬架系统直接关系到车辆的安全性、平顺性和操稳性,由于路面激励是随机激励,对悬架系统的状态监测一直是研究难点。该文提出一种新的悬架状态监测方法,利用仅需输出的平均相关随机子空间法识别模态参数,再通过模态参数变化对故障造成的悬架刚度变化进行监测。首先对平均相关随机子空间法在较高阻尼比下的识别效果进行分析,验证算法在悬架监测中的可行性;然后基于车辆七自由度振动模型对模态参数进行仿真识别,分析路面激励及噪声对识别结果的影响,并提出基于振型和模态能量的监测方法;最后设计利用9轴MEMS惯性传感器的试验方案对正常及故障状态进行监测,验证方法的可信度。     

虚拟激励算法下的汽车悬架振动分析

采用虚拟激励法和模态叠加相结合的方法,应用mathematic语言编制了二分之一车辆模型的悬架系统性能仿真程序。并以某汽车悬架系统为例,进行了模拟仿真计算,得到了给定测点在平稳路面激励下的响应功率谱矩阵和系统各阶振幅及相位差与路面激励频率之间的关系。计算结果表明该方法具有一定实用价值,可大体上反映出汽车振动性能及平顺性好坏。     

某轮胎辐射噪声的仿真

在ABAQUS中建立某型号轮胎的有限元模型,采用计算模态分析和实验模态分析对比,验证有限元模型的正确性,并仿真轮胎在某一路面上的滚动过程。基于声传递向量概念,结合有限元和边界元方法,利用MATV技术计算了随机激励下轮胎振动的辐射噪声响应,对轮胎辐射噪声进行分析研究。     

轮胎模态分析试验研究

为了优化轮胎模态试验方法,得到精确的轮胎模态参数,结合LMS Test Lab,研究模态试验三要素的选用原则,即测点布置、边界约束和激励形式的选取方式。试验结果表明：(1)对轮胎单一胎面进行模态测量,存在模态遗漏现象,且轴向与径向阵型易混淆,因此须进行轮胎三胎面(内胎面、正胎面、外台面)布点测量;(2)胎面整周少于36个测点时,轮胎高阶次花瓣阵型难以清晰呈现,因此须于三个胎面等角度间隔平行布置36×3个测点;(3)轮胎处于整车安装离地状态受激励时,支撑位移量微小,优于软绳约束状态;(4)激振器激励信号相干系数达到1,优于力锤锤击信号,并且使试验进行更加便捷与高效。本文提出了一种新的轮胎模态测试方法,并应用此方法得到了准确的轮胎模态参数,研究结果为轮胎噪声与振动控制提供了基本依据。     

基于环境激励的车辆系统工作模态试验分析

应用环境激励下模态试验参数识别的方法,在滚动振动试验台上对某高速轨检车进行工作模态试验,得到该车悬挂系统和车架结构的模态参数.试验结果表明,在试验条件下,用环境激励的方法能够得到铁道车辆悬挂系统和车体结构的各阶模态参数.通过对该车试验的结果分析,认为该轨检车的悬挂系统模态参数符合TB/T 3115-2005标准.但是车架第一阶弹性结构模态发生在频率等于8.668Hz处,建议提高该车车架结构的一阶弯曲刚度.     

环境激励下移动车辆对桥梁模态参数识别的影响研究

基于环境激励的模态参数识别方法在桥梁健康监测领域应用广泛,所识别桥梁的模态参数的变化常用来进行损伤识别。然而在模态参数识别过程中,移动车辆本身具有的质量属性被忽视,仅被当作为环境激励的一部分。桥梁损伤导致的模态参数变化将被移动车辆所引起的变化掩盖,影响后续损伤识别的效果。以随机子空间法为例,研究环境激励下的模态参数识别方法识别的桥梁模态参数的变异情况,并对比桥梁局部损伤导致的桥梁模态参数的变化量,结果表明局部损伤和移动车辆都会造成频率减小和振型改变,因此在实际模态测试中需要考虑移动车辆作用并剔除其影响。     

应用Test. Lab进行高速车体线路模态试验

针对高速列车的振动问题,通过线路模态试验进行车体结构模态参数研究,采用LMS test.lab振动噪声测试系统进行数据采集和分析后处理。基于环境激励模态试验方法及模态参数识别理论,运用PolyMax模态提取法,获取了车体的前三阶弹性模态参数和对应的模态振型,为车体结构优化设计提供依据。     

基于改进多目标粒子群算法的商用车悬架系统优化EI北大核心CSCD

为改善商用车辆的平顺性、安全性并减小轮胎动载对路面的破坏,以某6×4牵引列车为研究对象,建立12自由度振动力学模型。以车辆平顺性和轮胎动载为优化目标,选择前后悬架弹簧刚度、减振器阻尼系数为优化参数,设计了一种基于改进多目标粒子群优化算法MDPL-MOPSO的悬架系统多目标优化策略。悬架系统优化前后的结果对比表明,提出的改进多目标粒子群优化策略在改善车辆平顺性的同时,兼顾了轮胎动载对路面的损坏,具有较好的优化效果,对重型商用车在开发阶段平顺性和安全性优化评估具有一定的指导意义。     

基于改进多目标粒子群算法的商用车悬架系统优化

为改善商用车辆的平顺性、安全性并减小轮胎动载对路面的破坏,以某6×4牵引列车为研究对象,建立12自由度振动力学模型。以车辆平顺性和轮胎动载为优化目标,选择前后悬架弹簧刚度、减振器阻尼系数为优化参数,设计了一种基于改进多目标粒子群优化算法MDPL-MOPSO的悬架系统多目标优化策略。悬架系统优化前后的结果对比表明,提出的改进多目标粒子群优化策略在改善车辆平顺性的同时,兼顾了轮胎动载对路面的损坏,具有较好的优化效果,对重型商用车在开发阶段平顺性和安全性优化评估具有一定的指导意义。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。