This paper presents the results of a non-contact diagnostics of materials with low acoustic impedance and solid plates with air ultrasound. For generating and receiving acoustic waves in the air in the frequency range from 0.08 to 2 MHz ultrasound was developed automated measuring system and measurement technique in pulse mode. Generating and receiving ultrasound air carried with focused acoustic transducer. Determination of elastic properties of thin plates of solid work was carried out using a zero anti-symmetric Lamb wave modes. For diagnostic materials with low acoustic impedance used longitudinal acoustic wave. Was measured density expanded polystyrene and the velocity of longitudinal waves in it, calculated impedance and coefficient of elasticity of the material.
Department of acoustics, Faculty of Physics, M.V.Lomonosov Moscow State University. Moscow 119991, Russia.
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