Static and dynamic characterization of composition cork for sandwich beam cores R. A. S. Moreira • F. J. Q. de Melo • J. F. Dias Rodrigues Received: 11 November 2009 / Accepted: 25 February 2010 / Published online: 23 March 2010 Ó Springer Science+Business Media, LLC 2010 Abstract Composition cork can be regarded as an inter- esting solution for light-damped sandwich panels. Despite the emergent interest on these materials for structural applications, there is a lack of information concerning its static and dynamic properties. This study presents a com- parative study on a set of different experimental character- ization methodologies applied on a selected agglomerated cork for vibration damping applications. The obtained results support the assumption of an air spring/viscous-based mechanism ruling the low-frequency behaviour of these materials. This assumed behaviour is a result from the observations of the cellular microstructure of natural and composition corks. Indicative values for the Young’s mod- ulus, storage modulus and loss factor are provided as results from this study. In addition, a multilayer beam finite element, based on a mixed formulation, is proposed to be applied in an inverse characterization methodology and to be used also for the experimental validation tasks. The finite element proved to be efficient and accurate. Introduction Composite materials have been widely used in state-of-the- art structural applications, such as in the automotive, aeronautical and aerospace structural engineering fields, providing interesting and valuable stiffness/mass ratios, where they have been responsible for important progresses in design enhancement, safety and durability improvement and cost reduction, either in terms of manufacturing or operation and maintenance. The valuable performance of laminate composite structures in static or dynamic condi- tion applications has motivated a continuous development on new materials and laminate configurations, improved and cost-effective manufacturing processes and, specially, on more efficient modelling and design methods. An interesting laminate configuration, usually referred to as sandwich panel, combines the high stiffness of the external layers with an adequate internal core, which, for instance, can be deliberately designed to provide a signif- icant material damping capability. Such configuration enables an interesting combination of a highly resistant material applied in the skins and a core material able to dissipate large amounts of energy, usually as heat, thus reducing the structure vibration energy, which provides an efficient and inherent passive dynamic control. Such lam- inate materials have been gradually applied in some high- end and critical structures, like aeronautic components, aerospace frames and panels, among other justifiable applications. However, the continuous need for safer, qui- eter, reliable and cost-effective structures has motivated the structural design community, especially those acting on the transportation field, to face these damped sandwich struc- tures as promising solutions to succeed towards this goal. Soft elastomers with a high loss factor are the materials mostly applied in surface or sandwich damping treatments [1–3]. Despite offering a reduced mass and an important damping capability, the success of the application of these materials is often diminished when required to operate under a wide working temperature range. In such a case, it is impossible to design an effective single-layer damping R. A. S. Moreira (&)  F. J. Q. de Melo Departamento de Engenharia Meca ˆnica, Universidade de Aveiro, Campus Santiago, 3810-193 Aveiro, Portugal e-mail: rmoreira@ua.pt J. F. Dias Rodrigues Faculdade de Engenharia da Universidade do Porto, R. Dr. Roberto Frias, 4050-465 Porto, Portugal 123 J Mater Sci (2010) 45:3350–3366 DOI 10.1007/s10853-010-4356-0