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An experimental investigation of axisymmetrically loaded, plate-reinforced, circular holes

Published online by Cambridge University Press:  04 July 2016

G. Terry*
Affiliation:
Department of Aeronautics, Imperial College, London, *

Extract

The reinforcement for holes in tensile stress fields sometimes takes the form of an extensive thin plate attached to the sheet, especially if the reinforced region is of integrally machined or bonded construction. Such reinforcements are often placed eccentrically, that is on one side of the sheet only. It has been shown both experimentally and analytically that such an eccentrically placed reinforcement can promote considerable bending stresses.

Wittrick gives curves showing the effect of eccentricity in the case of the circular hole with an eccentrically located annular plate reinforcement in a plane, axially symmetric stress field. High, but only local, bending stresses exist which simple theory will not predict. The stresses are markedly higher than those given with the corresponding symmetric reinforcement. For example, under axisymmetric loading it is possible to design an optimum plate-reinforced neutral hole (i.e. the stress concentration factor is 1·0 in both sheet and reinforcement) if the reinforcement is deposed symmetrically about the plane of the sheet. If however it is placed totally eccentrically then for realistic sheet stresses bending raises the sheet concentration factor 2·0.

Type
Technical notes
Copyright
Copyright © Royal Aeronautical Society 1975 

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Footnotes

*

(Now with Hawker Siddeley Aviation Ltd, Woodford).

References

1. Levy, S., McPherson, A. E. and Smith, F. C. Reinforcement of a small circular hole in a plane sheet under tension. Journal of Applied Mechanics, Vol 15, p 160, June 1948.Google Scholar
2. Richards, T. H. Stress distribution in pressurised cabins: an experimental study by means of Xylonite models. ARC CP503, 1957.Google Scholar
3. Wittrick, W. H. On the axisymmetrical stress concentration at an eccentrically reinforced circular hole in a plate. The Aeronautical Quarterly, Vol XVI, p 15, February 1965.Google Scholar
4. Williams, D. Introduction to the Theory of Aircraft Structures, p 290. Edward Arnold Ltd, 1960.Google Scholar
5. Wittrick, W. H. Axisymmetrical bending of a highly stretched annular plate. Quarterly Journal of Mechanics and Applied Mathematics, Vol XVIII, p 11, February 1965.Google Scholar