Stress measurement of steel members based on ultrasonic amplitude spectrum cosidering temperature effect

To improve the applicability of the method for measuring the stress of steel members based on ultrasonic amplitude spectrum, the influence of temperature was investigated. Considering the change of ultrasonic wave velocity and the thermal expansion and contraction of steel members caused by temperature change, a modified formula for the effect of temperature was proposed. According to the modified formula, the calibration test of the temperature effect coefficient was carried out. From the results, the temperature effect mainly depends on the influence of temperature on the wave velocity. Based on this, the uniaxial stress measurement tests of steel members considering the temperature effect were carried out, and the reliability and accuracy of the method were verified. Furthermore, the main reason for the attenuation of ultrasonic signals under the influence of high temperature was explored. The results show that the increase of temperature intensifies the thermal motion of particles inside the steel specimen and weakens the ability of the propagation medium to transmit waves.