基于质量线法的驾驶室惯性参数识别试验研究

准确的驾驶室惯性参数,包括质量、质心位置、转动惯量和惯性积等,是整车动力学分析的基本参数。本文以某国产重卡整备驾驶室为研究对象,利用LMS数据采集系统测量频率响应函数,采用称重法获得重卡驾驶室的平面质心位置。从频率响应函数中提取质量线计算质心位置,与称重法结果进行对比,X方向误差为1.99cm,Y方向误差为0.68cm。该结果表明质量线法具有较高的测量精度。计算整备驾驶室的转动惯量、惯性积、主惯性矩和惯性主轴方向,并对引起试验误差的原因进行分析。     

汽车动力总成质心与惯性参数测试实验台的开发

介绍了一种基于三线扭摆法测试动力总成质心和惯性参数的测量方法和实验台的开发。该方法和实验台的特点是:(1)采用悬吊法悬吊被测试物体,因而容易保证被测物体的质心落在三线摆的扭摆轴线上;(2)计算质心与惯性参数的方法基于坐标变换,坐标变换中的数据由测量的坐标点计算得到。坐标点由三坐标测量仪测量得到,测试精度高。对一个长方形组合件的质心和惯性参数进行了测试,并和理论值进行了对比,表明了实验台具有测试简单、高效和文中的数据处理方法有效、精度高的特点。给出了一个动力总成质心与惯性参数的测试结果,分析表明基于该测试方法和数据处理方法建立的实验台和数据处理系统,具有较好的测试重复性和测试精度。     

用扭摆测量导弹主惯性参数的方法研究

介绍了用扭摆测量导弹惯性积的方法.通过6个不同的安装位置测量导弹转动惯量,进而计算导弹全部惯性张量、惯性主轴方向和主转动惯量.推导了计算惯性主轴夹角和主转动惯量的解析式,并进行了误差分析.由误差公式,可见该方法仅适用于大长细比试件测量.实例表明,当转动惯量测量误差小于0.5%时,惯性主轴夹角误差小于15',主转动惯量测量误差小于2%.     

大型刚体惯性参数识别的三线扭摆系统实验方法改进研究

精确获取汽车动力总成刚体惯性参数是发动机悬置系统设计的重要前提之一。利用三线扭摆法测量刚体单轴转动惯量精度较高的特点,基于表面固定点确定刚体方位的三点定位方法和测量6个~9个不同方位的多次测量原理,发展了一套适合于大型复杂刚体的惯性参数识别方法。关键技术有:(1)选取刚体表面三个定位点定义一个刚体随动坐标系以描述刚体方位;(2)通过测量刚体定位点至托盘表面参考点(定义一个整体坐标系)的距离,计算出定位点在整体坐标系下的坐标和两个坐标系之间的转换关系;(3)求出各组实验中在动坐标系下的刚体转轴方位和转动惯量;(4)运用最小二乘原理,求解多个转轴的最优交点得到动坐标系下的刚体质心坐标,求解由转动惯量转轴定理导出的线性方程组得到刚体惯性矩阵。实验方法中容易引起误差的环节较多,但是可以根据最小二乘原理进行逐级误差估计和控制。通过误差分析、长方体质量块实验验证和大量的汽车动力总成惯量参数识别实验,证明了该方法的实用性和可靠性。     

基于等效分析模型的发动机悬置系统优化设计

利用ANSYS有限元分析软件建立发动机悬置系统等效分析模型,将发动机动力总成悬置系统等效为一个惯性体和一个弹性体的复合体,各悬置元件简化为沿其3个弹性主轴方向的弹簧,并可准确体现动力总成的质量,转动惯量和激励力加载位置。利用ANSYS完成该模型的模态分析,并进行了能量解耦度和谐振频率的优化计算,结果表明,该等效建模方法是正确和可行的。该模型为在ANSYS中进行悬置系统模态分析优化和动力响应分析与隔振率优化提供了新的切实可行的简捷建模方式。     

考虑惯性参数测量误差的动力总成悬置系统优化方法

汽车动力总成的惯性参数（转动惯量和惯性积）通常采用实验方法进行测量,测量误差一般不超过3 %。动力总成悬置系统的固有特性与动力总成惯性参数、悬置刚度、位置、角度密切相关,从而悬置系统的固有频率和解耦率的理论设计值与其真实值之间必然存在一定程度偏差。采用均匀分布随机变量描述惯性参数,以悬置刚度为优化设计变量,提出稳健优化模型对某轿车悬置系统固有特性进行稳健优化。优化结果表明,与确定性优化方法相比,稳健优化方法可以较大幅度地提高频率、解耦率、频率间隔的稳健性。     

基于K&C试验台的汽车动力总成惯性参数精确测试方法研究

汽车动力总成惯性参数(质量、质心位置和转动惯量)的精确测试一直是汽车行业内难点.如何设计汽车动力总成惯性参数高精度的测试方法,是整个汽车测试行业共同关注的问题.本文以中国汽车技术研究中心悬架KC试验台为基础,对汽车动力总成惯性参数测试方法进行了研究.通过杠杆原理和转动惯量平行轴移动定理对试验测得结果进行计算,得到汽车动力总成的惯性参数,并对测试结果精度进行了标定验证.结果表明该方法具有非常高的测试精度,可进行汽车动力总成惯性参数精确测试.     

考虑坐标获取的试验模态分析的惯性参数识别方法

精准高效的坐标获取方式在模态分析的参数识别和性能优化等方面具有重要意义。基于模态试验中刚体振动的原理,分析其线参量和角参量的转换关系,推导出获取激励和响应坐标的方程,并结合质量线法得到惯性参数表达式。通过研究坐标获取误差的影响因素,搭建发动机动力学模型的仿真试验平台,进一步验证坐标获取与惯性参数识别的方法。以某型号变速箱总成为试验对象,利用基于最小二乘的卷积拟合算法(Savitzky-Golay, SG)对数据平滑滤波处理,对比电子三维坐标仪法、三维模型法与所提方法在坐标获取中的精度,然后选用质量线法识别惯性参数,并将其与MPC转动惯量测试平台计算的结果进行讨论。结果表明：相较传统方法,所提方法直接从模态试验中获取坐标,效率极大提升,成本显著降低,操作更加简便;同时几何坐标获取和质心坐标识别的最大误差在3 mm左右,转动惯量相对误差最大不超过7%,其精度优于部分测量方法,具有一定的工程应用价值。     

基于扭杆摆的汽车动力总成惯量参数测量实现

针对传统测量汽车动力总成惯量参数的繁琐操作,依据扭摆测惯量原理,设计了一个由称重传感器支撑的可升降的扭杆摆平台,利用三坐标仪建立动力总成坐标系,根据平台与总成上一些特征点的空间位置关系,求得任意姿态下动力总成坐标系各坐标轴与平台转轴的空间夹角,进而求得过动力总成质心惯量参数。标准块测试数据结果表明,利用该测量方法能够测得动力总成的惯性参数,且具有较高精度。     

基于坐标变换矩阵的汽车动力总成质心位置测量

基于一个称重平台,利用三坐标仪分别建立称重平台和动力总成坐标系,依据平台与总成上一些特征点的空间位置关系,求得两个坐标系之间的坐标变换矩阵。任意两次放置总成于称重平台,通过坐标变换矩阵求取通过总成质心的重力直线参数方程,求解两条直线所得到的交点就是动力总成的质心。标准块测试数据结果表明,利用该测量方法能够正确得到质心位置。     

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.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

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.     

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.     

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。     

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.     

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.