基于声弹性原理,研究板材厚度方向、螺栓轴向方向(以下简称z轴方向)宏观残余应力分布的超声无损检测方法。针对被测构件厚度不均匀对应力检测精度的影响非常大、检测原理繁杂不适合工程应用、拉伸实验中拉伸形变对应力系数测量精度的影响很大等问题,采取超声横波、纵波相结合的方法重新推导检测公式,并提出采用一发一收模式进行拉伸实验,通过对实验数据进行拟合,由公式计算出声弹性系数代替应力系数。然后结合插值、互相关等算法,采用VC++编制z轴方向残余应力超声检测软件并搭建检测系统。分别对性能为A2-70,4.8,8.8,长度依次为135 mm,100 mm,100mm的M20的螺栓进行拉伸实验,比对计算拉伸应力与检测拉伸应力,结果表明,该测量系统的绝对误差限为20 MPa,相对误差小于25%,且应力值较大时,相对误差有所减小,当应力值大于100 MPa时,相对误差小于5%,非常实用。 Based on the principle of acoustic elasticity, the nondestructive ultrasonic testing method is studied for the distribution of macroscopic residual stress in the direction of the thickness of the sheet and in the axial direction of the bolt (hereinafter referred to as the z-axis direction). In view of the fact that the thickness of member under test has a great influence on the accuracy of stress detection, the complicated testing principle is not suitable for engineering application, and the tensile deformation has a great influence on the measurement accuracy of stress coefficient in tensile test. The ultrasonic shear wave and longitudinal wave are combined The method is used to derive the detection formula again. The tensile test is carried out by using one-shot-one-off mode. The experimental data are fitted to calculate the acousto-elastic coefficient instead of the stress coefficient. Then combined with interpolation, cross-correlation and other algorithms, using VC ++ preparation of z-axis residual stress ultrasonic testing software and build detection system. Tensile tests were carried out on the bolts M20 with the performance of A2-70,4.8,8.8 and the lengths of 135mm, 100mm and 100mm respectively. The tensile stress and the tensile stress were calculated and compared. The results showed that The absolute error is limited to 20 MPa, the relative error is less than 25%, and the relative error is reduced when the stress is large. The relative error is less than 5% when the stress is greater than 100 MPa, which is very practical.