Plastic Strain Measurement with Electromagnetic Acoustic Testing Method Based on Surface Wave

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.