Ratchetting tests of a stepped beam under steady tension and cycling bending

Abstract

Seven identical stepped beams, made of a lead alloy, were loaded by steady tension and cyclic bending. Three bending moments superimposing equal hogging and sagging were used in the tests. Six different tensions were also used. After test of 15 cycles, most beams were re-loaded with a greater mean tension and the same cyclic bending moment. Strains were measured in the (circular arc) fillets at the step and in the shank.

Ratchetting strains per cycle decreased during each test; steady values were estimated and related to the load magnitudes. The common use of the 0.2 per cent proof stress as the yield stress for an equivalent elastic-perfectly-plastic materials has been shown to be extremely conservative.

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References

Fessler

Hyde

T. H.

‘Practical aspects of model creep work’, Third IUTAM Symposium on ‘Creep of Structures’, Leicester, 1980.

Fessler

Hyde

T. H.

‘The uni-axial and bi-axial creep properties of a material for modelling creep’, in

Non-linear problems in stress analysis (Edited by Stanley

), 1978 (Applied Science Publishers, London).

Cousseran

Lebey

Moulin

Roche

Clement

‘Ratchetting-experimental tests and practical method of analysis’, International Conference on Engineering Aspects of Creep, 1980 (IMechE, London) Vol. II, pp. 143–151.

Moreton

D. N.

H. W.

‘The extension and verification of the Bree diagram’, 6th Int. SMiRT Conf., Paris, 1981, Paper L10/2.

H. W.

Moreton

D. N.

‘The Bree diagram - origins and literature: Some recent advances concerning experimental verification and strain hardening materials’, in

Recent advances in creep and fracture in engineering materials and structures (Edited by Owen

D. R. J.

Wilshire

), 1980 (Pineridge Press).

Megahed

Ponter

A. R. S.

Morrison

C. J.

‘A theoretical and experimental investigation of material ratchetting rates in a Bree beam element’, Int. J. mech. Sci., 1983, 25, 917–933.

Hyde

T. H.

Sahari

B. B.

Webster

J. J.

‘The effect of material ratchetting on the incremental growth of beams subjected to steady axial loads and cyclic bending’, Int. J. mech. Sci., 1985, 27, 207–223.

Peterson

R. E.

Stress concentration design factors, 1953 (John Wiley, New York).

Bree

‘Elastic-plastic behaviour of thin tubes subjected to internal pressure and intermittent high-heat fluxes with application to fast-nuclear-reactor fuel elements’, J Strain Analysis, 1967, 2, 226–238.