度盘式非金属拉力试验机负荷示值误差测量结果的不确定度评定

度盘式非金属拉力试验机目前仍广泛应用于橡胶、线缆行业,本文对依据JJG157-2008《非金属拉力、压力和万能试验机检定规程》,以标准测力杠杆为标准器的度盘式非金属拉力试验机的负荷示值误差测量结果的不确定度进行了评定。     

一种工作测力仪检定装置

<正>一、现有的检定方法及缺陷按照JJG455-2000《工作测力仪检定规程》的规定,根据测力仪的规格选用相应量程的标准测力砝码、标准测力仪、标准测力杠杆、材料试验机或力标准机作为力标准器进行测试和检定。使用标准测力砝码、标准测力仪、标准测力杠杆等进行测试时,容易引起较大误差,同时也无法满足国家检定规程进行侧向检定。而使用材料试验机或力标准机进行测     

标准测力杠杆检定方法研究

标准测力杠杆有着准确度高、量程宽、便于携带、结构简单、与被检试验机连接方便、便于控制等优点,所以在5kN以下受拉的试验机检定工作中,测力杠杆为首选的标准器.近年随着杠杆使用量的迅速增加,杠杆的量值溯源也是各级计量检定部门必须面对的问题,因此探索和研究测力杠杆准确而高效的检定方法有着十分重要的现实意义.     

关于《弹簧拉压试验机》检定规程被替代的看法

弹簧拉压试验机作为测量弹簧的专用试验机。其计量性能有自身的特性。JJG609—1989《弹簧拉压试验机》针对这一特性作了较为完整的规定。JJF1134—2005《专用测力机》校准规范只涉及试验机（或测力机）的力值参数校准，并不包含弹簧拉压试验机其他方面的计量性能校准。JJG609—1989被JJF1134-2005替代以后，弹簧拉压试验机计量性能中的位移、平行度等计量参数就失去了校准依据，对力值的校准方法也比过去单一，并没有反映很多计量检测机构在用标准器（如标准测力仪）的实际测量方法。     

标准测力杠杆的使用误区

在力学的日常计量工作中，标准测力杠杆（以下简称为测力杠杆）有着准确度高（0.1级)；量程宽；何种轻，便于携带；结构简单，与被检试验机连接方便；容易操作等优点，所以对于5kN以下受拉的试验机检定工作，测力杠杆便成为了首选的标准器。     

钢丝绳张力测量仪的校准及不确定度评定

钢丝绳在使用中产生的疲劳和磨损会导致其承载能力降低或丧失,检测机构目前主要采用张力测量仪对钢丝绳的张力进行测量和监控。通过分析钢丝绳张力测量仪的基本结构和工作原理,对张力测量仪的校准方法和计量特性进行了研究;利用测力杠杆式试验机作为标准装置,通过配套砝码改变标准力值,实现了钢丝绳张力测量仪的实验室校准;通过对钢丝绳张力测量仪示值误差的不确定度进行评定,得到其扩展不确定度为0.17%FS。     

数字式回环形0.2级标准测力仪

为了提高标准测力仪的准确度等级,满足试验机的检定要求,我们研制成功回环形数字式0.2级标准测力仪,它的不同之处是测力元件设计为回环形,测量装置采用数字千分表,提高了测力仪的计量学特性,各项技术指标均达到或优于JJG 144—2007《标准测力仪》中0.2级的要求,而且还符合国际标准ISO376:2004《金属材料单轴式试验机检验用测力仪的校准》中Ⅰ级的要求。     

关于我国环状测力计的温度修正系数

一、引言为了满足工农业生产和国防、科研的急需,建国以来,国内生产了大批一百吨力以下的三等标准测力计,用以校准各种各样的材料试验机力值,并用于其他方面力值测量中。近几年,有关生产厂又生产了用于激光或光学显微镜测量的一些标准测力计环体。这些测力计首先在标准或基准测力机上进行定度,给出测力计所承受的载荷与变形特征数之间一一对应关系,据此再用来校准材料试验机或校     

基于测力环研发的试验机全自动检定装置

测力环主要作为计量标准器具,对力值进行量值传递或量值溯源,与测力传感器相比,具有寿命长、数据稳定、线性好、价格低、对现场要求低等优点,在试验机的力值检定或校准中得到大量应用。但测力环在使用中存在操作程序复杂、读数误差大、断点测量、工作效率低等缺点,影响了其性能的发挥。本文从解决当前测力环使用中存在的缺点出发,着力于测力环性能的提升,设计研发了一套试验全自动检定装置,可极大提升测力环应用中测量结果的准确性并提高检定效率。     

基于数显标准测力仪的力值检校方法研究

文章对基于传感器式标准测力仪的力值检校方法进行研究,介绍了测量标准的组成及工作原理,重点介绍系统检定软件的编制和操作方法,并对测量标准进行不确定度评定,该方法可有效提高材料试验机等力值检定校准的自动化程度。     

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)。