基于相位-频率测量的材料残余应力超声表征方法

Ultrasonic Characterization of Residual Stress in Materials Based on Phase-frequency Relationship

针对材料中残余应力无损检测的问题,提出一种基于相位-频率关系测量超声信号传播时间的方法,并以声弹性理论为基础,采用纵波和横波相结合的测量模式,建立残余应力的超声测量方法。该超声测量方法应用于焊接接头的残余应力测量,不仅能够表征两轴方向上的残余应力,而且还适用于短距离声时的精确测量,测量精度达到9 mm试样距离上0.3 ns的分辨率(加载应力为20 MPa)。制作16Mn钢材料的焊接接头,并采用所提出的超声测量方法对焊接接头的残余应力分布进行测量。同时,采用理论计算、X射线衍射技术等分别对16Mn钢材料的声弹性参数及焊接接头残余应力分布进行验证测量。研究结果表明基于相位-频率精确测量声时的残余应力超声测量方法具有较高的应力分辨率和较好的测量稳定性,可适用于焊接接头两轴方向上的残余应力表征。

To nondestructively test residual stress in materials,a time of flight measurement of ultrasonic propagation is proposed based on phase-frequency relationship and then an ultrasonic characterization of residual stress is developed based on acoustoelasticity,in which a combined measurement of longitudinal and transverse waves are used.The proposed ultrasonic measurement of residual stress can be applied not only to test the residual stress with a dual-directions,but also to make an exquisite measurement of time of sound flight in a short distance.The accuracy can reach to a sensitivity of 0.3 ns for the specimen of 9 mm＇s length under a stress load of 20 MPa.The proposed method is carried out to measurement the distribution of residual stresses in the welded joints of 16 Mn steels.Then,theoretical computations and X-ray diffraction also are used to verify the measured results.The result shows that the proposed ultrasonic method has a good repeatability and reliability in experiments,which can be used to test residual stress for welded joints in two axis directions.