关键词: 超声波, 高强度螺栓, 轴向应力检测

Abstract: To guarantee the reliability and security of the steel construction, the clamp load of the joint bolt should be under strict control, sometimes even the tension of the bolt should be measured on-line. Referring to the sonic elasticity principles, an indirect method is proposed for bolt tension measurement, based on the relation between the axial tension of high strength bolt and the time difference for the echo to return from the opposite end before and after the bolt is tightened. This method also takes the material factors and the clamp length into account. The method achieves high accuracy measurement by removing the measuring error caused by the discreteness of the thickness of the couplant and change in temperature. Based on the method, a new way on forecasting and revising the material factors is brought forward. The accuracy in bolt tension measurement is proved to be better than five percent, and thus is acceptable in most of the industry use.

Key words: Axial tension measurement, High strength bolt, Ultrasonic