Design and placement of passive acoustic measures in early design phases

The design and placement of passive measures for the improvement as well as the targeted adjustment of the vibroacoustic behaviour of technical products is often based on empirically determined rules or guidelines. Due to their general validity, potential for improvement often remains unused. Simulative optimisation procedures, on the other hand, are often very time-consuming due to the frequency dependence of acoustic phenomena and many iterations. This dissertation is dedicated to the development of identification criteria for passive measures in early design phases, which already provide a placement and design proposal after one or a few calculation steps. Essential adjusting screws for influencing the vibroacoustic behaviour of technical products are changes in mass, stiffness and damping. Therefore, beads, damping layers and point masses are used as representative examples of these adjusting screws. At the beginning of the thesis, a general classification of acoustic principles and measures in the methodological terminology of product development (Design to Acoustics) is given and a suitable acoustic assessment of design variants is discussed. The core of the thesis are numerical position and design studies of the exemplary measures on a rectangular plate, based on direct solutions using the finite element method. A suitable assessment quantity for the variants is the structure-borne sound level. The aim is to minimise this quantity in a defined critical frequency range. An application-oriented focus is set and a manufacturing-oriented design is taken into account. Correlations between distributions of physical quantities of the structure and suitable positions of the measure form the basis for deriving identification criteria.