超声幅值差法测量螺栓轴向应力研究

Measurement method of bolt axial stress using ultrasonic amplitude difference

该文基于受载多晶体介质中的超声波散射衰减理论,针对传统渡越时间法(TOF)对螺栓轴向应力测量精度较低的问题,提出一种利用超声回波幅值衰减的螺栓轴向应力测量方法。首先,推导瑞利散射范围内多晶材料中纵波和横波衰减系数,进一步得出螺栓受载前后的超声回波幅值与应力依赖关系的理论模型。此外,对理论模型进行数值仿真,验证模型的可行性。随后,搭建螺栓轴向应力超声测量系统,对比分析TOF法和幅值差法测量螺栓轴向应力的实验结果。实验结果表明,该文提出的基于超声散射衰减的幅值差法优于传统的TOF法,具有一定的工程应用价值。

Based on the scattering attenuation theory of loaded polycrystalline materials,this paper proposes a method for measuring bolt axial stress using ultrasonic echo amplitude attenuation to solve the problem of low accuracy of bolt axial stress measurement by traditional time-of-flight(TOF)method.Firstly,the attenuation coefficients of longitudinal and transverse waves of polycrystalline materials in the Rayleigh scattering range are deduced.Besides,the theoretical model of the relationship between the ultrasonic echo amplitude and axial stress before and after the bolt is loaded is obtained.Then,numerical simulation of the theoretical model was carried out to verify the feasibility of the model.Finally,an ultrasonic measurement system for bolt axial stress was built,and the experimental results of TOF method and amplitude difference method for measuring bolt axial stress were compared and analyzed.The experimental results shown that the amplitude difference method based on ultrasonic scattering attenuation is superior to the traditional TOF method.Therefore,the stress measurement method proposed in this paper has certain engineering application value.