应用电阻应变计的无缝线路纵向力测试原理及方案

针对无缝线路纵向力测试问题,在双向应变法原理的基础上,应用电阻应变计提出了一种新的无缝线路钢轨纵向力测试方案.综合考虑应变计热输出及同一钢轨断面温度非均匀分布的条件下,较为系统的阐述了基于电阻应变计的无缝线路纵向力测试原理,并对较为常用的既有测试方案的测试误差进行了对比分析.结果表明:钢轨断面温度的非均匀分布是测量误差的一个主要来源;采用电阻应变计测量无缝线路钢轨纵向及竖向应变时,必须考虑应变计的热输出以及钢轨纵向及竖向约束不同对相应的应变计热输出的影响;采用电阻应变计直接进行钢轨纵向力测量,无法将钢轨中的基本温度力及伸缩附加力进行分离;本文提出的测试方案不需附加补偿片,能够抵消荷载引起的弯曲应变,当两侧轨腰温差为2 ℃时,测量误差较之既有测试方案分别能够降低84.0%及60.3%. 

Test Principle and Test Scheme of Longitudinal Force in Continuous Welded Rail Using Resistance Strain Gauge

To test longitudinal force in continuous welded rails (CWRs), based on the bi-directional strain approach, a new test scheme using resistance strain gage was proposed. The test principle was systematically presented,and the errors of different test schemes were compared by taking into account the thermal output of resistance strain gage and uneven temperature distribution on the same rail section. The results show that, firstly, the test error mainly comes from uneven temperature distribution on the rail section. Secondly, when testing the longitudinal or vertical strain in CWRs, the thermal output of resistance strain gage and the influence of the longitudinal and vertical constraints of rail on the thermal output must be considered. In addition, all longitudinal force test schemes with resistance strain gage can not directly separate temperature force from the additional expansion force. Finally, the proposed scheme can offset bending strain caused by loads without additional compensation plate, and when both sides of the rail web have 2 ℃ temperature difference, compared to the two existing test schemes, the measurement error is reduced by 84.0% and 60.3%, respectively.