Comparison of methods for the numerical and experimental determination of structure-borne sound energy flows in technical structures

The reduction of the sound emission of technical structures can be realized in a most efficient way by influencing the structure-born sound transmission systematically. This can be passively achieved by using damping layers or ribbings. In order to make these measures as effective as possible, knowledge of the distribution and flow of structure-borne sound energy within a structural component is of great importance. With the help of the parameter structure-borne sound intensity, structure-borne sound energy flows can be quantified and visualized from excitation to sound emission. This paper examines and compares different methods for the numerical and experimental determination of the structure-borne sound intensity. The main focus is on the processing of measurement data acquired by a 3D laser scanning vibrometer and compared with the finite element model based on experimental data (model updating). Different methods for the calculation of structure-borne sound intensity with the help of measured surface velocities or optical strain measurements are shown. The influences of method-specific approaches, such as the use of filters in spatial and wave number domain, are evaluated and discussed. The methods are compared using the example of a simple structure which is a freely suspended thin plate, excited by an electrodynamic shaker. After the description and discussion of the individual approaches and the first results obtained, a qualitative and quantitative comparison of the numerical and experimental structure-borne sound intensity for different deflection shapes is made.