Evaluation of Tensile Deformation of 304 Steel Plate Using Electromagnetic Ultrasonic Lamb Waves Mixing

The paper presents the possibilities to estimate 304 steel plate’s plastic deformation using spectral analysis of the amplitude of difference and sum frequencies resulting from mixing of two Lamb waves with different frequencies. An electromagnetic acoustic transducer (EMAT) is used for the excitation of Lamb waves. The numerical modelling of the results of Lamb wave interference in a plate under tensile deformation is carried out; a comprehensive nonlinear factor is proposed and its sensitivity to the tensile deformation has been evaluated. Experimental verification of the modelling results is carried out. The experimental results show that this factor can be used to evaluate 304 steel plate’s tensile deformation quantitatively. This evaluation can eliminate the redundancy between difference frequency nonlinear parameter and sum frequency nonlinear parameter, as well as, improve the complementarity between the two parameters.