Electromagnetic acoustic testing technology has aroused extensive concern in the field of ultrasonic nondestructive testing.The characteristic of radiated sound field excitated by an electromagnetic acoustic probe is of great significance for the design of electromagnetic acoustic transducer (EMAT) and the application of electromagnetic acoustic testing techniques.

CHEN Qiuying, WANG Xiaomin, LI Mingxuan and MAO Jie of Institute of Acoustics, Chinese Academy of Sciences studied the characteristic of radiated sound field excitated within a non-ferromagnetic aluminum by an electromagnetic acoustic transducer consisting of circle-spiral coil and vertical bias magnetic field.

They present an improved force source model according to the principle of electromagnetic induction. Then the analytic displacement solution of sound field produced by that force source model is deduced. The tangential and normal directivities of shear and longitudinal sounds are calculated numerically and compared with experimental results. Experimental results conform well to the theoretical prediction. Theoretical and experimental study lays a foundation for optimization design and engineering application of the electromagnetic acoustic probe.

This research result was published on the recently issued Chinese Journal of Acoustics (2011, Vol. 30,No.1(pp:44-54)).