基于表面波的塑性变形电磁超声定量无损检测

摘要

电磁超声具有非接触、易于激发和接收表面波等优点，探讨了基于表面波的金属材料塑性变形电磁超声无损检测及定量方法。首先，建立了电磁超声有限元数值计算模型，开展了电磁超声表面波探头的优化设计，并在此基础上搭建了基于电磁超声表面波检测的塑性变形检测试验系统；其次，采用具有不同塑性变形的单轴和双轴拉伸不锈钢试件，分析了塑性变形的大小和方向与表面波传播速度之间的关系。最后，通过电磁超声系统测量表面波在两个正交方向的传播速度，实现了对不锈钢试件双轴塑性变形的定量无损检测。%Due to the non-contact feature and the ability of easily generating and detecting surfacewaves,in this work,electromagnetic acoustic transducers (EMATs)are studied for the nondestructive testing and evaluation of plastic strain in metal materials with using surface waves.Firstly,a numerical model based on finite element method (FEM)is established for EMAT simulation and optimization.And a surface-wave EMAT experimental system is constructed for plastic strain measurement.Secondly,the relationship between the magnitude and direction of the plastic strain and the velocity of the surface wave is studied by EMAT with using uniaxial and biaxial tensile stressing of stainless steel samples with various plastic strains.Finally,a quantitative NDT of biaxial plastic strain in stainless steels was realized with measuring the velocities of surface waves in two orthogonal directions by EMATs.