Advertisement

Effective Mechanical Properties of Closed-cell Foams Investigated with a Microstructural Model and Numerical Homogenisation

  • Nina-Carolin FahlbuschEmail author
  • Wilfried Becker
Chapter
Part of the Advanced Structured Materials book series (STRUCTMAT, volume 15)

Abstract

With their cost-effective production and advantageous properties (e.g. low density, low thermal conductivity, high specific stiffness) foams are an attractive material for an increasing number of applications. In this work the mechanical behaviour of closed-cell foams is analysed numerically. Besides the better understanding of the mechanisms of deformation and failure, the identification of the components of the effective elasticity tensor is the major aim of this study. Since the mechanical properties depend on the cellular microstructure, a representative volume element (RVE) of that microstructure is investigated. In an idealized manner a tetrakaidecahedral foam microstructure is considered and implemented in a finite element routine with periodical boundary conditions and a strain-energy based homogenisation concept is utilized. In this concept it is assumed that a macroscopically equivalent deformation state leads to the same strain energy in a representative volume element as in a homogenous “effective” medium with yet unknown properties [8]. The effect of imperfections, such as curved cell walls and geometry irregularities, on the effective mechanical properties is investigated and microbuckling instabilities of the cell-walls are discussed. The results are compared with literature and experimental data.

keywords

Closed-cell foam Homogenisation Imperfections 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    ABAQUS Documentation, version 6.9 (2009)Google Scholar
  2. 2.
    Demiray, S. (2007) Zur nichtlinearen Homogenisierung und mesoskopischen Simulation von Festkörperschwämmen. Dissertation. Technische Universität Darmstadt, Fachbereich Maschinenbau, Shaker Verlag, AachenGoogle Scholar
  3. 3.
    Evonik Röhm GmbH, Germany http://www.rohacell.com/product/rohacell/en/products-services/rohacell-wf/pages/ default.aspx and subordinate documents. Cited 25 Jan 2011.
  4. 4.
    Gibson, L.J., Ashby, M.F.: Cellular Solids: Structure and properties, 2nd edition. Cambridge University Press, Cambridge (1997)Google Scholar
  5. 5.
    Grenstedt, J.L.: Influence of wavy imperfections in cell walls on elastic stiffness of cellular solids. Journal of the Mechanics and Physics of Solids 46(1), 29–50 (1998)CrossRefGoogle Scholar
  6. 6.
    Grensted, t.J.L.: On interactions between imperfections in cellular solids. Journal of materials science 40, 5853–5857 (2005)CrossRefGoogle Scholar
  7. 7.
    Grenstedt, J.L., Bassinet, F.: Influence of cell wall thickness variations on elastic stiffness of closed-cell cellular solids. International Journal of Mechanical Sciences 42, 1327–1338 (2000)CrossRefGoogle Scholar
  8. 8.
    Hohe, J., Becker, W.: A probabilistic approach to the numerical homogenization of irregular solid foams in the finite strain regime. International Journal of Solids and Structures 42, 3549–3569 (2005)CrossRefGoogle Scholar
  9. 9.
    Kraatz, A.: Anwendung der Invariantentheorie zur Berechnung des dreidimensionalen Versagens- und Kriechverhaltens von geschlossenzelligen Schaumstoffen unter Einbeziehung der Mikrostruktur. Dissertation, Martin-Luther-Universität Halle-Wittenberg, Mathematisch-Naturwissenschaftlich-Technische Fakultät (2007)Google Scholar
  10. 10.
    Mills, N.J.: Deformation mechanisms and the yield surface of low-density, closed-cell polymer foams. Journal of Materials Science 45, 5831–5843 (2010)CrossRefGoogle Scholar
  11. 11.
    Simone, A.E., Gibson, L.J.: Effects of solid distribution on the stiffness and strength of metallic foams. Acta Materialia 46(6), 2139–2150 (1998)CrossRefGoogle Scholar
  12. 12.
    Ströhla, S., Winter, W., Kuhn, G.: Einfluss von Strukturstörungen auf die elastisch-plastischen Materialparameter zellularer Werkstoffe. In: Huber O., Bicker M. (Hrsg.): 2. Landshuter Leichtbau-Colloquium. Landshut: Leichtbau-Cluster, Fachhochschule Landshut, Tagungsband, 137-148 (2005)Google Scholar
  13. 13.
    Sue, J.: Effect of Microstructure of Closed Cell Foam on Strength and Effective Stiffness. Dissertation, Texas A&M University (2006)Google Scholar
  14. 14.
    Wang, J., Wang, H., Chen, X.: Experimental and numerical study of the elastic properties of PMI foams. Journal of materials science 45, 2688–2695 (2010)CrossRefGoogle Scholar
  15. 15.
    Youssef, S., Maire, E., Gaertner, R.: Finite element modelling of the actual structure of cellular materials determined by X-ray tomography. Acta Materialia 53, 719–730 (2005)CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  1. 1.Fachgebiet StrukturmechanikTU DarmstadtDarmstadtGermany

Personalised recommendations