Large inelastic deformation analysis of steel pressure vessels at high temperature: Dissertation

Kari Ikonen

    Research output: ThesisDissertationMonograph


    This publication describes the calculation methodology developed for a large inelastic deformation analysis of pressure vessels at high temperature. Continuum mechanical formulation related to a large deformation analysis is presented. Application of the constitutive equations is simplified when the evolution of stress and deformation state of an infinitesimal material element is considered in the directions of principal strains determined by the deformation during a finite time increment. A quantitative modelling of time dependent inelastic deformation is applied for reactor pressure vessel steels. Experimental data of uniaxial tensile, relaxation and creep tests performed at different laboratories for reactor pressure vessel steels are investigated and processed. An inelastic deformation rate model of strain hardening type is adopted. The model simulates well the axial tensile, relaxation and creep tests from room temperature to high temperature with only a few fitting parameters. The measurement data refined for the inelastic deformation rate model show useful information about inelastic deformation phenomena of reactor pressure vessel steels over a wide temperature range. The methodology and calculation process are validated by comparing the calculated results with measurements from experiments on small scale pressure vessels. A reasonably good agreement, when taking several uncertainties into account, is obtained between the measured and calculated results concerning deformation rate and failure location.
    Original languageEnglish
    QualificationDoctor Degree
    Awarding Institution
    • Helsinki University of Technology
    Place of PublicationEspoo
    Print ISBNs951-38-5856-1
    Publication statusPublished - 2001
    MoE publication typeG4 Doctoral dissertation (monograph)


    • nuclear power plants
    • pressure vessels
    • steel constructions
    • inelastic material deformation
    • creep
    • high temperature
    • reactor accidents
    • analysis
    • finite element method
    • modelling


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