Measurement of Acoustoelastic Effect of Rayleigh Wave in Plastically Deformed Silicon Steel Using Lensless Line-Focus Acoustic Microscopy

In this paper, a lensless line-focus poly(vinylidene fluoride trifluoroethylene) [P(VDF-TrFE)] ultrasound transducer and its V ( f , z ) defocusing measurement system have been applied to measure the acoustoelastic effect of Rayleigh wave propagating inside a plastically deformed silicon steel. The silicon steel sheets are subjected to uni-axial tensile loading so that different levels of permanent deformation ranging from 5 to 30 % are created. Since the ultrasound transducer is line-focused, Rayleigh wave velocities on each of the plastically deformed silicon steel samples can be measured along various directions relative to the loading direction. Finally, the correlation between Rayleigh wave velocity and plastic deformation is experimentally established in a direct, easy, and accurate way. The experimental results can then be used for the purpose of non-destructive evaluation of silicon steels which are widely used in industry.