超声纵横波螺栓载荷在线检测方法研究

针对传统扭矩法控制螺栓载荷误差过大的问题,提出使用超声纵横波法来进行螺栓载荷的检测方法。基于声弹性定理,建立螺栓应力与超声纵横波声时关系的螺栓载荷预测理论模型,避免螺栓原始长度的测量,真正实现无损检测。通过制定实验表征方法,设计磁力探头夹具,建立超声横纵波测螺栓载荷的实验平台,保证每次测量数据的稳定性与测量位置的一致性。对8.8级高强度双头螺栓轴向力进行实验验证,并结合理论模型获得声弹性系数。结果表明:螺栓的轴向应力与超声纵横波声时为线性关系,实验值与理论计算值在100~600 MPa的最大误差小于5.61%,误差绝对值的平均值在2%左右。

On line detection method of bolt load based on ultrasonic longitudinal and transverse waves

Regarding the present situation that the load error of bolt was too big when adopting traditional torque method,the ultrasonic longitudinal and transverse wave method was proposed to detect the load of bolt in this paper.Based on the acoustic elasticity theorem,a theoretical model for predicting the bolt load was established,which avoided the measurement of the bolt's original length and realizes non-destructive testing.Through the establishment of experimental characterization method and the design of magnetic probe clamp,the experimental platform of ultrasonic transverse and longitudinal wave measurement of bolt load was established to ensure the stability of every measurement data and the consistency of measurement position.The axial force of 8.8 grade high strength double-head bolt was tested by experiment,and the acoustic elastic coefficient was obtained by using the theoretical model.The results show that the axial stress of the bolt was linearly related to the ultrasonic longitudinal wave.The maximum error of experimental value and theoretical calculation value in 100-600 MPa is less than 5.61%,and the average error for absolute value is about 2%.