Research on Improving the Accuracy of Axial Stress Measurement Based on Ultrasonic Signal Sine Function Interpolation

Abstract

The accurate measurement of axial stress of bolts is an essential means to ensure the stable operation of an aero-engine. In the measurement of axial stress of bolt by ultrasonic method, the change of ultrasonic velocity caused by stress is not obvious. In order to ensure the accuracy of ultrasonic velocity measurement, it is necessary to measure the difference of ultrasonic propagation time accurately. A high-sampling rate signal is the prerequisite to improve the measurement accuracy of the ultrasonic propagation time difference. In this paper, by studying the characteristics of ultrasonic signals, sine function interpolation is used to improve the time resolution. The experimental results show that after the sine function interpolation is performed on the ultrasonic signal recorded at a sampling rate of 100 MHz, the average error of bolt axial stress measurement is reduced by 4.288 MPa. Therefore, the sine function interpolation method of ultrasonic signals proposed in this paper can effectively improve the measurement accuracy of the propagation time difference, thereby reducing the measurement error of the bolt axial stress in the large-scale high-speed rotating equipment represented by aero-engines.