Finite element analysis of acoustic beam interactions with plate at normal incidence. Comparison with a 3D angular spectrum method and measurements

The use of the finite element method (FEM) for studying the interactions of an acoustic beam with an elastic steel plate is discussed, in comparison with a 3D angular spectrum method (ASM) and measurements.

The use of the finite element method (FEM) for studying the interactions of an acoustic beam with an elastic steel plate is discussed, in comparison with a 3D angular spectrum method (ASM) and measurements. The on-axis sound pressure generated by a circular piston source at normal incidence through a steel plate is investigated. In the 3D ASM, aswell as in the measurements, pulses are utilized in order to propagate an incident wave towards the steel plate. In these methods the transmitted on-axis pressure is normalized to the incident on-axis pressure at the upper surface of the steel plate in order to calculate the transmitted frequency spectrum. Using a frequency domain 3D FEM continues waves are used instead of pulses, creating a standing wave pattern between the piston source and the steel plate. The transmitted on-axis pressure calculated using the 3D FEM contains therefore eects of this standing wave pattern. In an attempt to reduce these effects in the transmitted frequency spectrum, the total on-axis pressure at the upper surface of the steel plate is used instead of the incident on-axis pressure. In order to compare the 3D FEM to the 3D ASM and measurements, the relationship between these two on-axis pressures must be identied.