3-D voltage model for detection of sound radiated from anisotropic materials

The elastic behavior of composite materials has been characterized experimentally by employing a 3-D voltage calculation to model transmission or reflection experiments. With sound propagation along material symmetry directions, integration over the incident-plane angle alone is generally sufficient to model the transducer voltage accurately. In general material directions this integration must be extended to account for asymmetrical variations in the reflection or transmission coefficient out of the incident plane. Theoretical and experimental results illustrate this effect and the relationship between 2-D and 3-D calculations. Experimental measurements are used to in the reconstruction of viscoelastic properties in composite plates. The influence of the phi-dependent integration on the voltage, in the 3-D calculation, is particularly strong when the incident angles are small and the wave paths are large, as typically experienced in air-coupled measurements.