Metal Foams: A Design Guide

E
σ pl
(m)
10
1
0.1
0.01 0.1
Relative density
Alporas
Alulight
Alcan
ERG
Design for fatigue with metal foams 101
Figure 8.10 Predicted value of the transition hole size, Dt Eℓ/ pl,
plotted against relative density
criterion gives an accurate measure of the drop in fatigue strength due to
the presence of a hole. But these tests were done on small holes (maximum
diameter equals 30 mm). At the endurance limit, the extent of cyclic plasticity
is expected to be much less than the tensile ductility in a static tensile test,
and so υ0 is expected to be much less than the cell size ℓ. Consequently, the
magnitude of Dt is expected to be significantly smaller for fatigue loading
than for monotonic loading. This effect has been studied for fully dense solids
(Fleck et al., 1994) but experiments are required in order to determine the
appropriate value for tensile notched fatigue of metallic foams.
References
Ashby, M.F. and Jones, D.R.H. (1997) Engineering Materials, Vol. 1, 2nd edition, Butterworth-
Heinemann, Oxford.
Banhart, J. (1997) (ed.) Metallschäume, MIT Verlag, Bremen, Germany.
Banhart, J., Ashby, M.F. and Fleck, N.A. (eds) (1999) Metal Foams and Foam Metal Structures,
Proc. Int. Conf. Metfoam’99, 14–16 June 1999, Bremen, Germany, MIT Verlag.
Bao, G. and Suo, Z. (1992) Remarks on crack-bridging concepts. Applied Mechanics Reviews
45, 355–366.
Fleck N.A., Kang K.J. and Ashby M.F. (1994) Overview No. 112: The cyclic properties of engineering
materials. Acta Materialia 42(2), 365–381.
Fuchs, H.O. and Stephens, R.I. (1980) Metal Fatigue in Engineering, Wiley, New York.
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