用于冲击加速度测量的机械滤波器设计

强冲击脉冲结束后压电式加速度计往往会出现"零漂"现象,严重影响船舶设备冲击环境测量在中低频段的准确性。为压电式加速度计加装机械滤波器是减小"零漂"影响非常有效的手段,为此该文设计一种结构简单的机械滤波器,并基于两自由度系统冲击响应原理给出滤波器的性能设计方法。在此基础上,对安装机械滤波器的加速度计开展一系列的性能检测工作,结果显示机械滤波器的性能能够满足冲击试验的要求。     

机械式滤波器的研制及其在振动测试中的应用

一、前言以压电晶体为换能元件的加速度计在振动测试中应用十分普遍。因它在自身重量、频响范围、稳定性、抗冲击能力以及对外界温度的敏感性等重要指标方面,都是比较理想的。但在测试以高振级的高频和低振级的低频为特征的振动参数时,往往零漂严重,加速度计也常     

爆炸冲击环境下MEMS加速度传感器 的零漂分析

本文以石油行业中的爆炸冲击为研究背景,研究了MEMS加速度传感器在爆炸冲击环境下测量时存在的零漂问题的原因及解决方案.采用和MEMS加速度传感器电气模型等效的电阻式应变电桥,通过大量试验,排除了电路串扰、应变片自生信号等可能的原因,确定了电缆内由于摩擦生电效应产生的干扰信号是形成零漂的重要原因.在此基础上,选择不同类型的电缆进行了对比试验.试验结果表明:电缆的大柔性和低机械阻抗能够减少物理运动和应力波耦合的影响,石墨填充剂可将摩擦生电效应产生的电荷引入电气地,从而可有效改善MEMS加速度传感器在爆炸冲击环境下测量时存在的零漂问题.     

基于加速度计阵列的六自由度振动台测试方法研究

目前多自由度振动台缺乏方便有效的多自由度振动测试手段,通过探讨基于加速度传感器的六自由度振动测试方法,提出基于4只三向加速度计的加速度计阵列构型,依据六自由度运动系统方程对该构型的运动状态进行了理论推导,并设计了具体的封装方法,最后对封装的加速度计阵列构型进行了多自由度振动测试试验验证。试验结果表明:所提出的基于4只三向加速度计的加速度计阵列构型能够对角加速度进行测试与还原,简易可靠,可以作为多自由度振动的测试手段。本文提出的加速度计陈列构型有望被推广应用于现场低频振动测量或校准工作中。     

一种舰船低频冲击环境的新型测试原理与方法

舰船冲击环境是舰船设备抗冲击评估的基础输入数据,其最可靠的来源是实船抗冲击试验,其中低频冲击环境的测试工程上常采用低频振子、簧片仪等专用仪器,这些传感器存在过于笨重、仪器安装相对困难的问题,直接采用加速度计测试结果由于"零飘"导致误差大,其结果不可靠.为此,通过对低频冲击环境形成机理的分析,指出大型舰船低频冲击环境主要...     

排除TL—10000型弹簧试验机数字漂浮的新方法

TL－10000型弹簧试验机由山东省济南第二试验机厂生产。它是我国生产弹簧试验机的厂家之一，规格和型号很多。试验机大多采用S型应变片式传感器，它较其它形式的负荷传感器具有输出信号强，稳定性好等优点。该型弹簧试验机的读数系统，也就是负荷的指示部分由传感器输出信号，经过放大器，力值由数字板显示出来，准确直观，颇受用户好评。我区域有1台该型号的试验机，该单位弹簧试验多，试验量大，且负荷力值接近10kN。使用中发现零漂和力值显示漂越来越大，厂家来人也没有彻底解决。我们通过实际检查测试发现，零漂和力值显示的漂移根源…     

一种摆式大量程加速度计的设计

介绍了一种摆式大量程加速度计的工作原理.基于经典控制理论完成了加速度计各环节数学模型的建立,对加速度计悬丝支承、力矩器、位移传感器、伺服电路等部件进行了说明,阐述了该大量程加速度计的技术特点.     

SOI高g值压阻式加速度传感器与工艺实现

基于SOI技术,利用电感耦合等离子体硅深加工,设计制备了一种新型平面内振动高g值压阻式加速度计.该加速度计包括X轴向与Y轴向单元,采用扇形敏感质量块平板内振动结构.对称的布局方式,有效地消除了灵敏度的交叉干扰,提高了传感器的测量精度.测试系统分析出加速度传感器的灵敏度是1.170 μV/g.研究表明该加速度传感器可实现对量程高达25×104g加速度的测量.     

基于MESFET的GaAs基微加速度计的设计与性能测试

利用金属-半导体结型场效应晶体管(MESFET)作为微加速度计的敏感单元,设计一种4梁-质量块微加速度计结构.通过ANSYS分析软件进行仿真,敏感单位放置于悬臂梁根部的应力最大处,以获得最大的灵敏度.将封装好的微加速度计结构,利用惠斯通电桥测试电路,检测不同载荷下的输出特性,验证了微加速度计的力电耦合效应.测试结果表明,该微加速度计的线性度较好,其最大加载范围可达到24 g,且饱和区的灵敏度可达到4.5 mV/g,为高灵敏微传感器的研究奠定了一定的基础.     

振动速度场测试系统的分析与改进

针对某道路模拟平台系统的速度场测试系统,对薄体状构件的振型函数作了模态分析,利用多普勒效应,采用激光测速传感器中的响应传感器代替系统原来的位移计或加速度计,将其应用到平台测试系统,实现了对信号的非接触式测量.     

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.     

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。     

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)。