Calculation of the modal behavior of structured sheet metal

Abstract

Steel sheet metal is important for architecture, for mechanical engineering and vehicle construction due to its various usability and the fact that it is relatively easy to manufacture. When a regular structure is applied to such metal plates, their stiffness can be increased significantly in order to meet higher static requirements while keeping the same mass as an unstructured plate. Therefore, such structured metal plates are often used in lightweight constructions. However, at the same time any structuring of isotropic plates could lead to anisotropic characteristics, which, in turn, will affect the acoustic properties.In the study described in the present paper, the modal behavior of hexagonally structured metal plates was examined, which have been produced via a hydro-forming process. To this end, the eigenfrequencies and the shape of the corresponding eigenmodes were determined both experimentally and via finite element method (FEM). Then, the modal density as well as the driving point mobility obtained from the simulations were analyzed as a measure for the acoustical properties of the structured plates. Thereby, the influence of potential internal stresses due to the hydro-forming process, the effect of an unstructured edge as well as that of the boundary conditions were of particular interest. Keywords: Structured metal sheets, Hydro-forming, Modal analysis