高应变率下高温应变计灵敏度系数的校准方法

Calibration Method for Sensitivity Coefficient of High-temperature Strain Gauges at High Strain Rate

为校准高应变率下高温应变计在高温环境下的灵敏度系数,使用具有快速高温同步组装功能的高温、高应变率耦合的分离式Hopkinson杆装置对其灵敏度系数进行标定。将待校准的高温应变计粘贴在标准试样表面,并与试样处在相同温度与受力环境。对试样同步施加高温与高应变率加载,对比分离式Hopkinson杆上标准应变计信号与试样上高温应变计的输出信号,得到高温应变计的灵敏度系数。结果表明:采用新方法可以实现环境温度在293~1 473 K的范围,应变率在10^(3) s^(-1)量级的灵敏度标定;应力波弥散和衰减引起的校准灵敏度系数误差只与入射波幅值的积分呈线性关系,相对误差仅为2.39%;试样不均匀塑性变形导致的误差不超过1.6%;校准结果的合成不确定度为1.517%。新方法可以对高温应变计进行高温、高应变率环境下灵敏度系数的校准。

A new method is used to calibrate the sensitivity coefficient of the high-temperature strain gauge at high strain rate.The high-temperature strain gauge under calibration is pasted on the surface of a standard specimen by using the split Hopkinson bar with synchronous assembly device,and they are placed in the same temperature and stress environment.The specimen is subjected to impact loading at constant temperature.The sensitivity coefficient of the high-temperature strain gauge is obtained by collecting,calculating and comparing the output signals of the standard strain gauge on the split Hopkinson bar and the high-temperature strain gauge on the specimen.The calibration method applies to calibrate the sensitivity coefficient of guage at the strain rate of 10^(3) s^(-1) in the temperature range from 293 to 1 473 K.The error of the calibrated sensitivity coefficient caused by the dispersion and attenuation of stress wave have a linear relation with the integral of the amplitude of the incident wave,and the experimental relative error is only 2.39%.The error caused by the inhomogeneous plastic deformation of sample is less than 1.5%,and the uncertainty of calibrated results is 1.517%.The experimental results show that the proposed method can be used to calibrate the sensitivity coefficient of the high-temperature strain gauge at high temperature and high strain rate.