The paper presents the modeling of transmission of the ultrasonic plane wave through an uniform liquid layer. The considered sources of the ultrasonic wave were normal (straight) beam longitudinal wave probes and angle beam sheer waves probes commonly used in non-destructive testing. Coupling losses (CL) introduced by the presence of the coupling layer are discussed and determined applying the numerical procedure. The modeling applies to both monochromatic waves and short ultrasonic pulses with a specified frequency bandwidth. Model implementation and validation was performed using a specialized software. The predictions of the model were confirmed by coupling losses measurements for a normal beam longitudinal wave probe with a delay line made of polymethyl methacrylate (PMMA). The developed model can be useful in designing ultrasonic probes for high-speed rail track inspections, especially for establishing the optimal thickness of the water coupling layer and estimation of coupling losses, due to inevitable changes of the water gap during mobile rail inspection.
The plane wave propagation in a homogeneous, monoclinic, generalized thermoelastic solid medium with thermal relaxations is studied. Three types of plane waves: quasi-P (qP), quasi-thermal and quasi-SV (qSV) waves, are shown to exist. The analytical expressions for their dimensional velocities of propagation are obtained. The velocities of these waves are found to depend on the angle of propagation. Angles of reflection for plane waves are found to be different from their angles of incidence. Numerical computations are carried out to show the variations of velocities of plane waves for different parameters. Effects of anisotropy, frequency and thermoelastic coupling coefficient on wave propagation are observed.
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