共查询到20条相似文献,搜索用时 171 毫秒
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本文提出一种应变测量方法,可以在保持分辨力的前提下,扩大应变量程(应变分辨力为0.2μ∈,应变量程为1199μ∈)。方法是对工作应变片和补偿应变片分别用恒流源供电,测量其输出差值。并且,与微机联机,使测量中大量的修正和补偿可以自动完成,直接得到数据处理结果。 相似文献
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电阻应变片的选择电阻应变片的好坏直接影响测量的准确度.下面仅从热输出和疲劳响应来说明选择应变片的重要性.1.热输出在温度变化环境中进行应变测量时,应变 ... 相似文献
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电阻应变片是目前常用的测量应变传感元件.应变片特性的标定方法影响到测量值的准确程度.本文介绍我们测量应变极限的方法,并对灵敏系数标定梁表面应变的计算公式提出一点看法. 相似文献
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动态力学量的光电测试法 总被引:1,自引:1,他引:1
本文对光电法用于动态力学量测试的可行性进行了系统的分析和研究,并与传统的电阻应变片法作了比较。结果表明,这一方法能可靠地用于准静态直至=10~5s~(-1)范围内的质点位移、速度、试件应变、应变率、应力和泊松比等力学量的测量,其中质点位移和试件大应变为直接测量,能有效提高测试精度. 相似文献
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超大应变测量中输出线性化问题的解决 总被引:2,自引:0,他引:2
分析了大应变测量的非线性问题及解决方法,介绍了应用双稳流电源电路原理研制的超大应变测量仪,它能完全线性地把应变计电阻变化转换成电压输出,再由4位半数字表显示出应变值的大小,该仪器测值准确、使用方便。 相似文献
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结构优化半解析灵敏度及误差修正改进算法 总被引:1,自引:0,他引:1
提出结构半解析灵敏度分析及其针对刚体位移的误差修正方法的改进算法, 构建灵敏度分析与误差修正项可分离形式. 该方法实现简便, 数值精度不受摄动步长与单元数目的影响. 首先从总体角度推得静力问题的误差修正半解析灵敏度分析方法, 提出了位移误差修正灵敏度列式, 并给出算法实施途径; 然后将此思路推广于自振频率、屈曲临界载荷问题, 提出了相应的计算步骤. 随后, 给出梁单元与壳单元误差修正项的具体推导方法, 并分别使用两种单元构建有限元模型进行算例测试. 结果表明, 该方法适用于多种分析类型, 数值精度不受单元数目与摄动步长的影响. 由于灵敏度分析与误差修正项可以分开计算, 该方法支持将误差修正项直接叠加于灵敏度求解结果进行误差修正, 使已有灵敏度分析程序得到充分利用. 尤其对于复杂工程结构的优化设计, 特别是形状优化设计以及尺寸、形状混合优化设计, 相比于原误差修正方法, 实现更为简便, 效率有所提升, 能为半解析灵敏度分析方法及其程序实现提供新的思路. 相似文献
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基于大型炉体焊接残余应力测试的盲孔法研究 总被引:1,自引:0,他引:1
为提高炉体焊接残余应力测试精度,对传统的盲孔法进行改进,即在测点打孔后多次扩孔并增加孔深;通过对SM400ZL钢焊接残余应力测试时的应变释放系数A,B进行实验标定,得出多组应变释放系数值,计算可得残余应力的估算值,并对不同状况下的残余应力值进行比较.通过大拉力标定试验得出SM400ZL钢盲孔的孔边塑性变形对测量精度的影响和塑性修正公式.结果表明,改进的盲孔法能够更准确地测得焊接残余应力值,测量结果经塑性修正,最大误差减小到2%以下.测试方法和结果可直接在相关的工程实际中应用. 相似文献
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本文提出了计算外补偿线路的串并联电阻的公式。用该公式确定的外补偿线路和组合式温度自补偿应变计结合起来能构成一种可调整的应变计。这种应变计很容易消除水泥混凝土由于线膨胀系数分散而引起的热输出,外补偿线路引起应变计灵敏系数的下降,可以通过修正来解决。本文亦展示了验证试验结果,还探讨了上述公式在焊接式半桥自补偿应变计中的应用。 相似文献
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Full-field strain measurements of the inside of an agricultural tyre using digital image correlation
This paper investigates strain measured on the inside of an agricultural tyre with large tread-blocks during a series of static tests using a novel measuring system. The full field strain measurements may be used in the development of a tyre which is capable of estimating tyre forces from strain measurements. The strain measurement system makes use of a calibrated stereo camera system on a mechanical stabilizing system that keeps the cameras pointed at the inside surface of the tyre in contact with the road while the wheel rotates. A static tyre test rig is used to displace the road surface relative to the tyre in the vertical and longitudinal direction. The large tread-blocks caused strain concentrations on the inner surface as the tyre deforms to comply with the road surface. Vertical and longitudinal tests each produce unique strain patterns in the contact patch region. Relationships between the applied forces and strain measurements were developed and showed that these relationships are near linear with R2 values above 0.97. The strain measurements also show that the location where strain gauges, for single point strain measurements, are placed inside the tyre is very important on large lugged tyres. 相似文献
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本文介绍了在重水反应堆中进行应变测量的若干技术成果,主要是较好地解决了用在核辐射条件下,有水流冲刷的环境中的应用变计的粘贴与防护技术。在具有核辐射的环境中测试,通常选用聚酰亚胺胶作粘结剂。但是这种胶需在高温条件下固化,如果被测构件较大,是无法实现的。经测试筛选出具有防水防辐射性能的常温固化胶,并介绍了可用航空导线替代具有抗辐射性能的铠装电缆在堆内进行测量问题。采用有关措施后,经标定,在核辐射前后应 相似文献
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To determine a machine’s mechanical condition it is of importance to know the radial bearing forces in the machine. Radial
forces are caused by magnetic pull forces in the generator, clamped shafts, mass unbalance and flow properties around the
turbine. Measuring the shaft displacement in the bearing or the bearing housing acceleration is not sufficient for status
determination of a vertical hydropower unit. It is the magnitude and frequencies of the radial forces in combination with
structure properties which give information as to whether a measured value is harmful or not. This paper presents an alternative
method for measurement of radial bearing load in a hydropower unit. The method presented in this paper is based on strain
measurements on pivot pins. The pivot pins are placed behind the bearing pad and the radial loads acting on the pad propagate
through the pivot pin. New pivot pins were purchased and equipped with strain gauges. The new pivot pins were calibrated and
a transfer function between applied load and measured output voltage was identified for each pivot pin. After calibration
the pivot pins were installed in a vertical hydropower unit. Measurements were performed for several different operating modes
of the hydropower unit. To verify that the measured load levels were of right order of magnitude, the radial bearing loads
were calculated from numerical simulations of bearing properties and shaft eccentricity measurements. The two methods for
determining bearing load showed almost the same results. This indicates that either method can be used to determine bearing
load. 相似文献
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An Experimental Method to Determine the Tensile Strength of Concrete at High Rates of Strain 总被引:1,自引:0,他引:1
In the present work, dynamic tensile strength of concrete is experimentally investigated by means of spalling tests. Based on extensive numerical simulations, the paper presents several advances to improve the processing of spalling tests. The striker is designed to get a more uniform tensile stress field in the specimen. Three methods proposed in the literature to deduce the dynamic strength of the specimen are discussed as well as the use of strain gauges and a laser extensometer. The experimental method is applied to process data of several tests performed on wet micro-concrete at strain rates varying from 30 to 150/s. A significant increase of the dynamic tensile strength with strain-rate is observed and compared with data of the literature. In addition, post-mortem studies of specimens are carried to improve the analysis of damage during spalling tests. 相似文献
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以薄膜传感器悬臂梁作为等效模型,通过传感器的应变效应对三向力测量技术进行了研究。为提高薄膜传感器的应变输出响应,对悬臂梁上布放薄膜传感器的位置加设弹性结构,研究了三向力测力模型输出电压与传感器所在位置应变的关系;分析了受力位置对测力模型输出响应的影响关系,结合实验验证了其工作原理、测力模型应变输出响应与可控尺寸参数的关系。研究表明:该测力模型可实现三向力测量,各个方向最大测量误差均在9%以内,悬臂梁宽度方向x和高度方向z的交叉干涉误差分别为2.84%和3.37%;当悬臂梁自由端受力位置发生变化时,测力模型输出响应只在梁长度方向y上发生变化。 相似文献
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Strain gauges are used together with the corresponding gauge factor to relate the relative electrical resistance change of the strain gauge with the strain of the underlying material. The gauge factor is found from a calibration on a stiff material - steel. Nevertheless, the gauge factor depends on the stiffness of the calibration material and ideally the calibration should be done on a similar material as tested. In practice, the gauge factor found by the strain gauge manufacturer is often used. The paper documents that even for moderately stiff materials such as glass-fibre composites a significant error is found on the strain measurements obtained by the strain gauges. This is documented both experimentally and numerically. A stiffness, also test sample and strain gauge geometry dependent correction coefficient of the gauge factor is proposed. A correction coefficient covers material stiffnesses ranging from 1 GPa to 200 GPa. 相似文献
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Vehicle safety and performance can be dramatically improved if force or friction measurement of the tyre-terrain interface is known. Since the tyre-terrain interface is responsible for the majority of forces acting on the vehicle, this region has received a lot of attention in vehicle dynamics. Direct measurement of the tyre-terrain interface is difficult since it is hidden by the tyre and terrain. A lot of research has been conducted on the inside of tyre using accelerometers or strain gauges with research more focussed on passenger car tyres and very little work performed on agricultural tyres with larger lugs. This study performs strain measurements using point measurement, from strain gauges, and full field measurement, using a stereo camera measurement system, of the inside of an agricultural tyre on a drum test rig during vertical and lateral loading. Results show similar trends when compared to results on passenger car tyres, however the mounting of the strain gauge relative to the lug is shown to play a large role in the developed strain. Linear relationships between the applied tyre force and strain were obtained in different direction with R2 values above 0.97. 相似文献
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The Blade Tip Timing (BTT) measurement system is a technique to measure vibration parameters of a rotating bladed disk. In particular for synchronous vibrations the BTT provides signals versus the rotation speed of the disk starting from the measurement of the time of arrival (TOA) of each blade under the tip timing probes. The signals must be post processed in order to obtain the interesting parameters of each blade vibration. The paper presents a method to extract the main parameters (amplitude and frequency) in resonance condition from the tip timing measurements. The proposed method is a revision of the already existing well known Two-Parameter Plot (2PP) method which requires a minimum of two probes. Improvements to the existing 2PP method are here suggested mainly in the part of engine order identification.The proposed method is then applied to the BTT measured signals coming from a rotating bladed disk excited at different engine orders. At the same time on the disk the vibration of one blade was detected by strain gauges. The strain gauges were calibrated and they provide the reference values of the vibration parameters. The vibration parameters derived by the proposed method are in agreement with those obtained by the strain gauges methodology. 相似文献