STP1211: Novel Methodology for Fatigue Lifetime Prediction

    Puskar, A
    Professor, University of Transport and Communications, Žilina,

    Pages: 16    Published: Jan 1993


    Abstract

    A unique fatigue lifetime equation offers the possibility of predicting residual fatigue lifetime of a material. Derivation of this lifetime equation is based on a correlation between the total and plastic strain amplitude during cyclic loading. A ratio determined as the reciprocal value of the elasticity modulus degradation is evaluated from the continuous measurements of the specimen resonance frequency in a resonance testing machine. For successful application of this procedure, coefficients and exponents for a fatigue curve, Coffin/Manson curve and cyclic stress-strain curve, or coefficient and exponent for the new fatigue lifetime equation are needed. This new equation and the well-known equations of cyclic plastic response are fully compatible. Measurements of dynamic elastic (secant) modulus of a virgin specimen and of a specimen after previous cyclic loading then provide an opportunity to evaluate the residual fatigue life.

    The verification of the proposed procedure was performed using a carbon steel with 0.485 mass % carbon at a test frequency of 20.2 kHz, using three different rates of increase for the total strain amplitude before starting ordinary fatigue testing (loading ramps).

    Keywords:

    elastic modulus degradation, carbon steel, ultrasonic frequency, cyclic stressstrain curve, Coffin/Manson curve, fatigue life equation, loading ramp, lifetime prediction


    Paper ID: STP15084S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP15084S


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