Similitude analysis of vibrating plates with damping

• Applicant: Professor Dr.-Ing. Tobias Melz, since 12/2023
• Subject Area: Acoustics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 517342666

Structure-borne and airborne sound can be measured on a scaled model of an original mechanical structure and transferred to the original using scaling laws. Experimental effort can thus be reduced. In addition, as much information as possible can be obtained from one experiment, e.g., by transferring the results of the model experiment to several size levels of a structure. Principles of similitude theory are therefore assumed. This allows vibroacoustic quantities (natural frequencies, vibration velocities, sound pressures, etc.) to be adequately transferred from the scaled model to the original (or vice versa). Previous work has assumed that damping characteristics of the model and original structure are identical. The applicant showed that damping properties of model and original can differ significantly in a statistical manner. This reduces the prediction accuracy of model tests; their practical use is limited to the few cases in which equal damping between model and original can be ensured. A changing damping in scaled model tests is caused by the facts that (1) the boundary conditions of the original structure can only be represented approximately in the model and (2) variations in the material properties scatter among model and original. This leads to distorted similitude conditions. In order to clarify the exact relationships, existing similitude methods first need to be further developed in the project so that damping properties of vibrating mechanical structures can be scaled. A higher order similitude theory (finite similitude theory) has been proven to overcome current limitations of existing scaling methods on geometrically distorted plates and beams. This approach will be extended in this project to perform model tests on vibrating structures, where the damping of original and model are different. Finally, with this knowledge, the prediction accuracy of vibroacoustic model tests can be improved by transferring the damping properties as well as the vibration properties from model to original. Thus, the project will push the applicability of model tests in vibroacoustics significantly beyond current possibilities.

• DFG Programme: Research Grants
• International Connection: Italy, United Kingdom
• Cooperation Partners: Dr. Keith Davey; Professor Dr. Sergio De Rosa
• Ehemaliger Antragsteller: Professor Dr.-Ing. Christian Adams, until 11/2023