Image Number 2 for United States Patent #5321333.
A low frequency torsional transducer for the generation and/or reception of shear waves in a substantially solid medium. The transducer includes a spool like radiating structure to which are fixedly attached spaced piezoelectric elements. The elements undergo shear movement upon being electrically excited or upon receiving shear waves. This shear movement causes the opposite ends of the radiating structure to move torsionally. The torsional movement causes radiation of shear waves which can be detected by a sensor and used to determine the degree of support for shear wave propagation in the media.