Hostname: page-component-7479d7b7d-q6k6v Total loading time: 0 Render date: 2024-07-13T06:00:01.159Z Has data issue: false hasContentIssue false
  • English
  • Français

The Indentation and Nailing of Cellular Materials

Published online by Cambridge University Press:  21 February 2011

M. Fátima Vaz  and
M. A. Fortes
M. Fátima Vaz
Affiliation:
Departamento de Engenharia de Materiais, Instituto Superior Ticnico, Av. Rovisco Pais, 1000 Lisboa, PORTUGAL
M. A. Fortes
Affiliation:
Departamento de Engenharia de Materiais, Instituto Superior Ticnico, Av. Rovisco Pais, 1000 Lisboa, PORTUGAL
Get access

Abstract

An experimental study was carried out on the indentation of cellular materials under quasi-static conditions. The study concentrated on a closed cell rigid polyurethane foam, but other cellular materials were tested. Load (F) - penetration depth (x) curves were obtained for various types of indenters which fall into two main types: sharp indenters (e.g. normal nails) and blunt indenters (e.g. flat ended nails). The F(x) curves are similar for the two types with an initial high slope region followed by a lower slope region in which F increases linearly with x. Nevertheless, the mechanisms of indentation are completely different, with a blunt indenter pushing the material under it and a sharp indenter pushing it radially as it penetrates. The effect of dimensions and shape of the indenters on the F(x) curves was investigated and scaling relations could be derived. Penetration-removal cycles clarify the differences between the two types of indenters, and give additional information on the mechanics of indentation. The experiments were complemented with scanning microscope observations of sections of the indented material. Two approaches are advanced for modelling indentation: a discrete approach in which the cellular structure is taken into account and a continuum approach.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 207: Symposium I – Mechanical Properties of Porous and Cellular Materials , 1990 , 41
Copyright
Copyright © Materials Research Society 1991

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Wilsea, M., Johnson, K. L. and Ashby, M. F., Int. J. Mech. Sci. 17, 457 (1975).CrossRefGoogle Scholar
2. Salem, S.A.L., Al-Hassani, S.T.S. and Johnson, W., Int. J. Mech. Sci. 17, 211 (1975).Google Scholar
3. Gibson, L.J. and Ashby, M.F., Cellular Solids - Structure and Properties, 1st. ed. (Pergamon Press, 1988) ch.5, p.150.Google Scholar
4. Stern, E.G., Trans. ASME 72, 987 (1950).Google Scholar
5. Noguchi, M. and Sugihara, H., Bull. Wood Res. Inst. 25, 1 (1961).Google Scholar
6. Noguchi, M. and Sugihara, H., J. Jap. Wood Res. Soc. 6, 252 (1961).Google Scholar
7. McMahon, T.A. and Bonner, J.T., On size and life (Scientific American Library, Freeman and Co. New York, 1983).Google Scholar
8. Bishop, R. F., Hill, R. and Mott, N.F., Proc. Phy. Soc. 57, 147 part 3 (1945).Google Scholar
9. Forrestal, M.J., Okajima, K. and Luk, V.K., J. Appli. Mech. 55, 755 (1988).CrossRefGoogle Scholar
10. Timoshenko, S.P. and Kriger, K.W., Theory of plates and shells, 2nd ed. (Mc Graw-Hill, 1989) ch.3.Google Scholar
11. Johnson, K. L., Contact Mechanics, 1st ed. (Cambridge University Press, 1985) ch.3.CrossRefGoogle Scholar