Characterization of the Stiffness Properties of Honeycomb Core Structures via an Homogenization Technique 2007-01-2168
Lightweight honeycomb sandwich structures have been increasingly employed in the automotive industry: from parcelshelf to loadfloor applications.
There can be an infinite variety of possible solutions adopted for these parts depending on the choice of the core geometries (such as hexagonal, tubular, sinusoidal.. etc) and of the materials. To cope with the need to have in the design phase an efficient prediction tool, a mathematical model based on a multi-scale asymptotic technique for the dynamic description of honeycomb core structures is presented in this paper.
The technique is employed to evaluate the equivalent orthotropic model of any honeycomb core geometry and material. The derivation is based upon an asymptotic analysis for periodic structures developed by A.Bensoussan et al. .
The equivalent orthotropic model is derived by applying this asymptotic analysis procedure directly to Cauchy's partial differential equations that describe the dynamics of the honeycomb structure. The method is then totally general and it presents no restrictions in terms of cell geometry or cell material. A detailed analysis is shown for typical honeycomb cores, and the results are validated with full numerical modeling techniques based on Finite Elements. Furthermore a numerical/experimental comparisons on the dynamic behavior of a sandwich panel with a common core geometry is provided.
The validation activity shows a very good agreement between the results of the homogenized and of the detailed FE models and confirms the reliability of the proposed procedure, which can be applied in the design of honeycomb sandwich and in the identification process of efficient cellular core layouts.