Abstract:
A line-focus transducer for material characterization is constructed. The transducer construction is readily achieved by conforming commercial polyvinylidene fluoride (PVDF) film to a cylindrical (convex) surface, followed by casting a tungsten-powder-loaded epoxy resin backing material into an attached aluminium case housing. Five transducers with acoustic impedance of 2.69, 3.91 and 7.37 Mrayl and backing material thickness of 6 mm, and other two with acoustic impedance of 3.91 Mrayl and backing material thickness of 9 and 12 mm respectively, are constructed. All transducers are tested by using pulser-receiver circuit, the obtained pulse width in the range of 0.60 to 0.88 microsecond. The one with the shortest pulse width is used to characterize samples material properties, by the defocusing technique. To measure the longitudinal wave speed, Rayleigh wave speed and attenuation coefficient of materials, from which the Youngs modulus, shear modulus, bulk modulus and mass density may be deduced. Five samples: soda-lime glass, alumina, aluminium, iron and stainless steel have been measured, and the deduced values are comparable to the values appearing in standard references.