Evaluation of Stiffness Terms for Z -cored Sandwich Panels
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Evaluation of Stiffness Terms for Z-cored Sandwich Panels D. Zangani & M. Robinson & A. G. Gibson
Received: 9 May 2007 / Accepted: 7 August 2007 / Published online: 11 September 2007 # Springer Science + Business Media B.V. 2007
Abstract This paper presents a model for the stiffness terms of composite sandwich panels with structured cores (referred to as ‘z-core’ panels). Truss-cores, corrugated-cores and double-corrugated cores containing a polymeric foam were considered. The model was validated, both through finite element simulation and through comparison with the results of experimental three point bend tests on panels. A parametric study was performed to assess the performance of the different reinforced panel configurations. Keywords Sandwich composites . Structured core . Modelling . Finite element analysis
1 Introduction Sandwich panels are now widely used for lightweight structures because of their favourable strength-to-weight or stiffness-to-weight ratios. Modelling of simple sandwich panels can readily be accomplished using laminate theory [1] or sandwich theory [2] in simple cases, or finite element analysis (FEA) for more complex ones [3]. Recent processing developments have now rendered it possible to manufacture panels where the core is reinforced by means of trusses or corrugated structures connecting the skins: we will use the general term ‘z-core’ to describe structures of this type. Advantages of z-core panels can include improved strength, due to the suppression of skin debonding, as well as substantially improved impact performance. We present here a fairly straightforward numerical method of modelling and design of z-cored panels, the
D. Zangani (*) D’Appolonia S.p.A., Via S. Nazaro, 19, 16145 Genova, Italy e-mail: [email protected] M. Robinson : A. G. Gibson School of Mechanical & Systems Engineering, University of Newcastle upon Tyne, Stephenson Building, Newcastle upon Tyne NE1 7RU, UK
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Appl Compos Mater (2007) 14:159–175
predictions of which will be compared with the results of simple bend tests and FEA predictions. The panel can be modelled as an equivalent homogeneous orthotropic thick plate, with appropriate elastic constants. Several authors have provided models for the elastic constants of sandwich panels, including Libove and Hubka [4] and Fung and co-authors [5, 6] who derived models for the elastic constants of panels with various types of load-bearing core. Collier [7], derived the stiffness terms of stiffened composite panels using classical laminate theory and modelled large stiffened panel structures with a single plane of shell finite 2D elements. Qiao and Wang [8] derived the elastic constants for panels with sinusoidal honeycomb cores and Lok and Cheng [9] studied truss-core sandwich panels, where the skin plates and the internal webs are fabricated using an extrusion process. Z-core sandwich panels have been recently introduced in the railway and automotive areas [10].
2 Geometry of z-core Panels Figure 1 shows the core configurations considered in the
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