Research on the strain gauge mounting scheme of track wheel force measurement system based on high-speed wheel/rail relationship test rig

Purpose-This paper aims to analyze the stress and strain distribution on the track wheel web surface and study the optimal strain gauge location for force measurement system of the track wheel.Design/methodology/approach-Finite element method was employed to analyze the stress and strain distribution on the track wheel web surface under varying wheel-rail forces.Locations with minimal coupling interference between vertical and lateral forces were identified as suitable for strain gauge installation.Findings-The results show that due to the track wheel web’s unique curved shape and wheel-rail force loading mechanism,both tensile and compressive states exit on the surface of the web.When vertical force is applied,Mises stress and strain are relatively high near the inner radius of 710 mm and the outer radius of 1110mmof the web.Under lateral force,high Mises stress and strain are observed near the radius of 670mmon the inner and outer sides of the web.As the wheel-rail force application point shifts laterally toward the outer side,the Mises stress and strain near the inner radius of 710 mm of the web gradually decrease under vertical force while gradually increasing near the outer radius of 1110 mm of the web.Under lateral force,the Mises stress and strain on the surface of the web remain relatively unchanged regardless of the wheel-rail force application point.Based on the analysis of stress and strain on the surface of the web under different wheel-rail forces,the inner radius of 870 mm is recommended as the optimal mounting location of strain gauges for measuring vertical force,while the inner radius of 1143 mm is suitable for measuring lateral force.Originality/value-The research findings provide valuable insights for determining optimal strain gauge locations and designing an effective track wheel force measurement system.

再谈“strain gauge”等若干名词术语的译意

为了进一步规范应变片技术的学术名词术语,现把常容易出错的一些学术用语的翻译和释义做一些介绍。并用相应的图示加以进一步说明,以供从事应变片、传感器技术研究及应用人员参考。

DEVELOPMENT FOR HIGH PRECISION SIX COMPONENT STRAIN GAUGE BALANCE

The measurement accuracy of a wind tunnel balance is the key factor to improve the measurement accuracy for a test model in the wind tunnel. In order to improve the measurement accuracy of the wind tunnel balance, a great deal of investigation is carried out in China. This paper summarizes a program to improve the measurement accuracy of wind tunnel balances. In the program, the investigation is carried out in three aspects (1) designing a drag component of the balance in low interactions (2) choosing high quality foil strain gauges with temperature self-compensation (3) choosing the excellent gauges and mounting them meticulously. As an example, these research achievements are applied in a φ18 six component balance. The measurement accuracy of a GB-04 standard model in a transonic wind tunnel with the φ18 six component balance comes up to the advanced world standard.

Experimental Investigation on the Dynamics of Pipes Conveying Fluid Based on Strain Gauge Test

Dynamical performance of pipes conveying fluid on board is of great importance to the reliability of machinery.The dynamic equation of a simply supported wet pipe conveying fluid is presented,taking structural damping of the pipe and viscidity of the fluid into consideration.And the equation is also solved by using Galerkin's method.Modal identifications based on strain gauge test are carried out on both dry pipes(without fluid in it) and wet pipes(pipes conveying fluid).It is concluded from the comparison of the results that both natural frequency and the damping ratio decrease as the pipe filled with fluid,but the mode shapes vary little.Variation of equivalent damping factor is also tested.Experimental results reveal that the equivalent damping factor of fluid and the damping ratio depend greatly on the initial deformation,and fluid induced damping decreases the universal damping ratio of the pipes conveying fluid.

Strain Effect of Manganin Transverse Piezoresistive Gauge and Measurement of Dynamic Transverse Stresses

Manganin piezoresistive gauges have been extensively used in dynamic stress measurement for decades.It is noted,however,that when used to measure transverse stresses,considerable strain effect is caused as the consequence of change of electrical resistance resulted from bending of wires in the longitudinal-strain-experiencing sensing element of the gauge,a phenomenon discussed in this paper theoretically as well as experimentally.This effect yields unwanted signals to blend with output piezoresistive signals and is not negligible,hence decreases measurement accuracy sizably if not properly handled.To overcome this drawback,a new type of manganin transverse piezoresistive gauge has been developed by authors of this paper,which can reduce the resistance increment to acceptable low level so as to effectively bring the adverse effect under control.

AN IMPROVED CALIBRATION METHOD FORDYNAMIC CHARACTERISTICSOF STRAIN GAUGE

Investigation on the calibration method for dynamic characteris-tics of strain gauge is of great importance for improving the accuracy of dy-namic strain measurement. In this paper a new excitation control method ofcalibration system is introduced. The me

The strain seismograms of P- and S-waves of a local event recorded by four-gauge borehole strainmeter

At a sampling rate of 100 samples per second,the YRY-4 four-gauge borehole strainmeters（FGBS） are capable of recording transient strains caused by seismic waves such as P and S waves or strain seismograms. At such a high sampling rate, data from the YRY-4 strainmeters demonstrate fairly satisfactory self-consistency. The strain tensor seismograms demonstrate the senses of motion of P waves, that is, the type of seismic wave travels in the direction of the maximum normal strain change. The observed strain patterns of S waves significantly differ from those of P waves and should contain information about the source mechanism. Spectrum analysis shows that the strain seismograms are consistent with conventional broadband seismograms from the same site.

Study and application of vibrating wire strain gauge in monitoring cable tension of FAST cable-net

A cable net structure is selected to support its reflecting triangular aluminum panels of FAST(five-hundred-meter aperture spherical radio telescope).To ensure the security and stability of the supporting structure,cable force of typical cables must be monitored on line.Considering the stringent requirements in installation,accuracy,long-term stability and EMI(Electromagnetic interference),most of the commonly used cable force measurement methods or sensors are not suitable for the cable force monitoring of the supporting cable-net of FAST.A method is presents to accomplish the cable force monitoring,which uses a vibrating wire strain gauge to monitor the strain of linear strain area at the anchor head.Experiments have been carried out to verify the feasibility.The method has a series of advantages,such as high reliability,high accuracy,good dynamic performance and durability,easiness of maintenance,technical maturity in industry and EMI shielding.Theoretical analysis shows that there is a linear relationship between the cable body force and anchor head surface strain,and experimental results proves a good linear relationship with excellent repeatability between the cable body force and anchor head surface strain measured by the vibrating wire strain gauge,with a linear fit better than 0.98.Mean square error in practical measuring is 2.5t.The relative error is better than 4%within the scope of the cable force in FAST operation which meets practical demand in FAST engineering.

Damage detection of a thin plate using modal curvature via macrostrain measurement

Plate structures are employed as important structural components in many engineering applications. Hence, assessing the structural conditions of in-service plate structures is critical to monitoring global structural health. Modal curvature-based damage detection techniques have recently garnered considerable attention from the research community, and have become a promising vibration-based structural health monitoring solution. However, computing errors arise when calculating modal curvatures from lateral mode shapes, which result from unavoidable measurement errors in the mode shapes as identified from lateral vibration signals; this makes curvature-based algorithms that use a lateral measurement only theoretically feasible, but practically infeasible. Therefore, in this study, long-gauge fiber Bragg grating strain sensors are employed to obtain a modal curvature without a numerical differentiation procedure in order to circumvent the computing errors. Several damage indices based on modal curvatures that were developed to locate beam damage are employed. Both numerical and experimental studies are performed to validate the proposed approach. However, although previous studies have reported relative success with the application of these damage indices on a simple beam, only one damage index demonstrated the capability to locate damage when the stiffness of the local region changed near the sensor.

Review of graphene-based strain sensors

In this paper, we review various types of graphene-based strain sensors. Graphene is a monolayer of carbon atoms, which exhibits prominent electrical and mechanical properties and can be a good candidate in compact strain sensor ap- plications. However, a perfect graphene is robust and has a low piezoresistive sensitivity. So scientists have been driven to increase the sensitivity using different kinds of methods since the first graphene-based strain sensor was reported. We give a comprehensive review of graphene-based strain sensors with different structures and mechanisms. It is obvious that graphene offers some advantages and has potential for the strain sensor application in the near future.

Preparation and Characterization of Resistive Strain Sensor Based on Braided Skin-Core Rope

This study proposed a new yarn-like strain sensor on the basis of the braided skin-core rope,and investigated the effect of braiding structures on the sensing properties of sensors.The morphology and electromechanical properties of the strain sensor with different braiding structures were compared and evaluated.The results show that the sensing performance of the sensor from a braided skin-core rope depends on both the number of yarns in braiding and the metallized process of braided rope.Generally,the present stretchable skin-core rope-based sensor provides a basis for the formation of a highly sensitive sensing structure.

A new device for stress monitoring in continuously welded rails using bi-directional strain method

The technology of continuously welded rails （CWRs） is important in modern railway track structures. To measure rail stress, resistance strain gauges are preferred due to their good stability, sensitivity, and esistance to external interference. Based on the bi-directional strain method, we present a new method for measuring longitudinal rail stress using resistance strain gauges and develop a monitoring device for rail stress to realize long-term and multi-point measurement. Also relevant experimental verification and analysis are conducted. Results indicate that under various constraints the rail stress–strain values can be calculated just with the measured total longitudinal strain and total vertical strain. Considering the measurement error caused by sectional feature of sensors, we put forward a correction equation applicable to different stress conditions. Although the temperature values of the four full-bridge stress gauges can offset each other, the measurement error caused by rail flexural strain can also be eliminated to a certain extent at the same time, the nonuniform distribution of rail cross section temperature and unbalanced flexural strain still affect the measurement error. The experimental results also show that the developed rail-stress-monitoring sensor is suitable for measuring rail stress with reliable working performance.

Longitudinal growth strains in five clones of Eucalyptus tereticornis Sm

We studied the variability in longitudinal growth strains and wood basic density in five-year old trees from five clones （one tree per clone） of Eucalyptus tereticornis. Mean longitudinal growth strain in clones ranged from 466 to 876 μm. There was a significant difference between clones in growth strains and wood basic density. Clone 10 exhibited maximum growth strains and basic density, whereas clone 3 and clone 7 exhibited minimum growth strains and basic density, respectively. Within a tree, the growth strain variation with tree height was high but statistically insignificant while within tree variation in basic density was very small. There was no specific trend in variation in either strain or density within a tree. There was 5% 200% difference in growth strain on opposite sides of the logs. However two strains showed a strong positive correlation. There was a moderate positive association of wood basic density and mean growth strains in logs. The variation around the periphery emphasize the need to measure strain more than one, preferably on opposite sides at the same height, on a tree to know the mean strain level for the purpose of selection of clones.

Residual strains of aluminum alloy characterized by nanoindentation

A formula was brought forward to correlate residual strain with hardness measured by nanoindentation method. Using the formula, residual strains in prestrained aluminum alloy samples were evaluated. In order to compare with the calculated strain, such values were also measured by strain gauge method. The results show that the differences of the residual strain obtained by nanoindentation and strain gauge method are not more than 8%, which shows that the formula is suitable for characterizing residual strain of aluminum alloy.

用于特殊环境的薄膜应变计的制备与表征

使用磁控溅射制备了卡玛合金薄膜应变计,研究了退火温度对薄膜微观结构的影响,测试了薄膜的电学性能以及压阻响应特性,并进行了环境实验。结果表明,随着退火温度升高,薄膜的电阻率逐渐下降,电阻温度系数则逐渐升高,在室温下有最小的电阻温度系数(TCR),约为59.9×10^(-6)/℃,经过200℃退火处理的薄膜应变计的应变灵敏度系数(GF)为2.2,TCR为64.4×10^(-6)/℃。经历温湿循环、盐雾、霉菌试验后,薄膜的压阻特性变化不大,能耐受海洋特殊环境。

利用FBG传感器测试高温合金和陶瓷基复合材料的应变

利用光纤布拉格光栅(FBG)应变传感器测量了高温合金和陶瓷基复合材料的应变特性,并与电阻应变片的测量结果进行了对比分析.将FBG应变传感器与电阻应变片分别粘贴在高温合金和陶瓷基复合材料试件的正、反面上,利用力学试验机对2种试件施加载荷,分别利用FBG解调仪和应变测试仪对FBG应变传感器和电阻应变片的信号进行实时解调.研究得出:FBG应变传感器与电阻应变片在一定的应变范围内,测量结果符合较好.因此,FBG应变传感器可代替电阻应变片,实现对材料的应变测量.

试验应变片动态管理数据库设计与应用

本文针对结构强度试验应变片补片问题,提出了基于动态管理的应变片数据库架构,通过对应变片进行快速编号和扫描,对应变片进行实时出入库管理,实现了应变片数量及分布动态变化的可视化,并对常规应变片和补片进行在线管理,避免了数据上传的延迟,对提高试验效率具有一定的意义。

钢纤维混凝土的断裂损伤过程分析

为探究钢纤维的掺入在混凝土断裂中发挥的作用,通过应变片电测法和数字图像相关(DIC)法对楔入劈拉试件进行加载试验,分析了素混凝土和钢纤维混凝土两种材料的裂纹扩展行为。利用应变片电测法得到断裂损伤区内虚拟裂纹张开位移随荷载的变化和不同荷载时的张开位移分布的变化,绘制成曲线;由DIC法得到试件的应变场变化云图,并计算出张开位移,与应变片电测数据对比分析。结果表明:钢纤维能阻挡裂缝贯通发展,钢纤维试件在破坏过程中承载能力变化更为平缓;DIC法的运用在试件达到峰值荷载前是可靠的。另外,基于双K断裂准则计算了试件的最大承载力,与试验结果基本吻合;通过非线性断裂的裂纹黏聚模型及损伤因子计算法,结合试验数据,给出黏聚裂纹张开位移与损伤变量在断裂过程区的分布规律。

高温退火对合金衬底上PtW薄膜应变计性能影响研究

为实现航空发动机热端部件健康监测,采用磁控溅射技术在GH4169高温合金基板上制备了一种耐高温的PtW薄膜应变计。该应变计由NiCrAlY过渡层、热氧化生成TGO层、YSZ/Al_(2)O_(3)复合绝缘层和PtW功能层构成。采用SEM和EDS分析了退火前后PtW薄膜的微结构。研究结果表明,退火后PtW薄膜晶粒长大,电阻率下降,W元素含量减少且在晶界处发生富集。通过悬臂梁施加应变,研究了退火前后PtW薄膜应变计在室温~600℃下的应变敏感性能。结果表明,其应变灵敏系数均随温度升高而逐渐降低,且退火后薄膜应变计的应变灵敏系数随温度变化更为显著。该PtW薄膜应变计应变测量量程超过1400με且重复性良好,在航空航天高温部件表面应变测试领域具有广阔的应用前景。

基于应变片法的非平行多裂纹相互作用及起裂机理

通过计算3条非平行斜裂纹的最大应力强度因子KⅠ,kmax(θ)和KⅡ,kmax(θ),揭示其相互作用机理,并采用多裂纹起裂准则预测非平行多裂纹的起裂参数。对含3条非平行斜裂纹的红砂岩试样开展单轴压缩试验,采用应变片测量方法监测裂纹尖端附近的应变,以确定裂纹起裂顺序。结果表明:裂缝相对倾角的变化对破坏轨迹影响不大且多裂纹尖端很少同时起裂。单轴压缩下含3条非平行斜裂纹红砂岩试件破坏形式可分为两种:翼裂纹贯通和翼裂纹-次生裂纹贯通。断裂机理均为Ⅰ型(拉伸)起裂。预测结果与试验结果吻合较好,验证了理论结果的有效性。