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Conference Article: Experimental and theoretical work for the analysis of creep ratcheting and creep buckling of HTR components

Breitbach, G.; Schubert, F.; Nickel, H. (Kernforschungsanlage Juelich GmbH (Germany, F.R.). Inst. fuer Reaktorwerkstoffe); Seehafer, H.J. (Internationale Atomreaktorbau GmbH (INTERATOM), Bergisch Gladbach (Germany, F.R.))

Abstract

At very high temperatures loaded metallic structures undergo inelastic deformations due to creep. The generated creep strains are connected with stress relaxations, stress redistributions and/or progressive deformations. The superposition of primary and secondary stresses may lead to enhanced creep deformations. This phenomenon is known under the name ''creep ratcheting''. The interchange of elastic and creep strains is important for its understanding. Theoretical and experimental work is discussed in this paper. In mainly load controlled situations the behaviour of the material can be described by a nonlinear viscous flow law (Norton power law), where elastic effects can be neglected. The creep collapse of a tube is an example of such a slow flow process. Theoretical calculations based on Hoff's model and on Finite Element Analysis are compared with experimental results.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
High temperature metallic materials for gas-cooled reactors. Proceedings of a specialists meeting held in Cracow, 20-23 June 1988
International Atomic Energy Agency, Vienna (Austria). International Working Group on Gas-Cooled Reactors
IWGGCR--18, pp:183-190