Influence of Ramberg-Osgood fitting on the determination of plastic displacement rates in creep crack growth testing

Nam Su Huh, Yun Jae Kim, Kee Bong Yoon

    Research output: Contribution to journalArticlepeer-review

    6 Citations (Scopus)

    Abstract

    This paper investigates the effect of the Ramberg-Osgood (R-O) fitting procedures on plastic displacement rate estimates in creep crack growth testing, via detailed two-dimensional and three-dimensional finite-element analyses of the standard compact tension specimen. Four different R-O fitting procedures are considered: (i) fitting the entire true stress-strain data up to the ultimate tensile strength, (ii) fitting the true stress-strain data from 0.1% strain to 0.8 of the true ultimate strain, (iii) fitting the true stress-strain data only up to 5%; strain and (iv) fitting the engineering stress-strain data. It is found that the first two fitting procedures can produce significant errors in plastic displacement rate estimates. The last two procedures, on the other hand, provide reasonably accurate plastic displacement rates and thus should be recommended in creep crack growth testing. Several advantages of fitting the engineering stress-strain data over fitting the true stress-strain data only up to 5% strain are discussed.

    Original languageEnglish
    Pages (from-to)277-286
    Number of pages10
    JournalFatigue and Fracture of Engineering Materials and Structures
    Volume30
    Issue number4
    DOIs
    Publication statusPublished - 2007 Apr

    Keywords

    • Creep crack growth testing
    • Displacement partitioning
    • J-integral
    • Plasticdisplacement rate
    • Ramberg-Osgood fit

    ASJC Scopus subject areas

    • General Materials Science
    • Mechanics of Materials
    • Mechanical Engineering

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