A simplified ultrasonic immersion technique for materials evaluation

A simplified ultrasonic immersion technique has been developed to measure leaky surface and bulk waves in solid materials by using specially designed lensless, line-focus polyvinylidene fluoride (PVDF) transducers with a large aperture and a short focal distance. Based on a simple methodology, this technique offers precise velocity measurements for these wave types, from which material properties, such as the elastic moduli, can be determined. Directional leaky wave measurements with this technique have been used to detect material anisotropy, as well as to determine the depth and orientation of a surface crack. The effects of plasma-spray conditions on the acoustic properties of sprayed ceramic coatings possessing rough surfaces and porous microstructures have also been measured using this technique.