The Research on the Ultrasonic Measurement of the Bolt Axial Stress by the Longitudinal and Transverse Wave

摘要

This paper presents new methods to measure the axial stress or the prestress in a bolt by ultrasonic longitudinal and transverse wave, which is convenient and accurate. New relationship among the bolt stress, the material characteristics of ultrasonic transit speed, the clamping distance, the transit time of longitudinal waves and transverse wave and the temperature is derived from the relation of the velocity of ultrasonic transit along the axial direction and the axial stress, the elastic constants etc. It is taken into account that the temperature affects the ultrasonic velocity under the action of the stress. This method simplifies the testing and calculating process. The experimental results show that the absolute error of measurement is less than ±4Mpa for the prestress of a bolt in assembling, and less than ±10Mpa for the stress of a bolt in use .