STP833: A Failure Assessment Approach for Handling Combined Thermomechanical Loading

    Bloom, JM
    Technical Advisor and Research Engineer, Applied Mechanics Section, Babcock & Wilcox, A McDermott Company, Research and Development Division, Alliance, Ohio

    Malik, SN
    Technical Advisor and Research Engineer, Applied Mechanics Section, Babcock & Wilcox, A McDermott Company, Research and Development Division, Alliance, Ohio

    Pages: 25    Published: Jan 1984


    Abstract

    This paper presents a failure assessment approach for the handling of combined thermomechanical loading of nuclear pressure vessels. The proposed approach is based on a failure assessment curve that accounts for the thermal and mechanical stresses in terms of the elastic stress intensity factor with a plastically corrected crack length. The square of this stress intensity factor divided by the effective elastic modulus is added to a J-integral deformation plasticity solution term. The result is valid for the full range of material/structural behavior, from linear elastic to fully plastic. The fracture behavior parameter, the total J-integral, can then be formulated in terms of a failure assessment curve to account for the combined loading states.

    The proposed approach was benchmarked using a modified Babcock & Wilcox version of the ADINA computer program. The program generated incremental plasticity finite element crack solutions for a single edge cracked plate and a circumferentially flawed cylinder subjected to thermomechanical loadings. The ADINA finite element results agreed quite well with the proposed failure assessment approach.

    The failure assessment approach is illustrated by a sample problem of a postulated accident condition, based on the occurrence of an overcooling transient (thermal loading) combined with an uncontrolled repressurization (mechanical loading) of a typical nuclear reactor vessel.

    Keywords:

    fracture, plastic collapse, failure assessment diagram, thermomechanical loading, nuclear pressure vessels, ADINA


    Paper ID: STP32555S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP32555S


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