STP1292: Prestraining and its Influence on Subsequent Fatigue Life

    Kalluri, S
    Senior research engineer, NYMA, Inc., NASA Lewis Research Center, Cleveland, OH

    Halford, GR
    Senior scientific technologist and senior research engineer, NASA Lewis Research CenterMcGaw Technology, Inc., ClevelandFairview Park, OHOH

    McGaw, MA
    Senior scientific technologist and senior research engineer, NASA Lewis Research CenterMcGaw Technology, Inc., ClevelandFairview Park, OHOH

    Pages: 14    Published: Jan 1996


    Abstract

    An experimental program was conducted to study the damaging effects of tensile and compressive prestrains on the fatigue life of nickel-base, Inconel 718 superalloy at room temperature. To establish baseline fatigue behavior, virgin specimens with a solid uniform gage section were fatigued to failure under fully reversed strain control. Additional specimens were prestrained to 2, 5, and 10% (engineering strains) in the tensile direction and to 2% (engineering strain) in the compressive direction under stroke control and were subsequently fatigued to failure under fully reversed strain control. Experimental results are compared with estimates of remaining fatigue lives (after prestraining) using three life prediction approaches: (1) the linear damage rule (LDR), (2) the linear strain and life fraction rule (LSLFR), and (3) the nonlinear damage curve approach (DCA). The Smith-Watson-Topper parameter was used to estimate fatigue lives in the presence of mean stresses. Among the cumulative damage rules investigated, the best remaining fatigue life predictions were obtained with the nonlinear damage curve approach.

    Keywords:

    prestraining, metal fatigue, cumulative fatigue damage, mean stress, life prediction, nickel-base superalloy


    Paper ID: STP16145S

    Committee/Subcommittee: E08.04

    DOI: 10.1520/STP16145S


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