STP519: Cumulative Fatigue Damage Under Complex Strain Histories

    Landgraf, RW
    Scientific Research Staff, Ford Motor Company, Dearborn, Mich.

    Pages: 16    Published: Jan 1971


    Abstract

    The accumulation of fatigue damage under complex mechanical histories is approached from a cyclic deformation viewpoint. Smooth axial specimens of SAE 1045 steel in two heat treated conditions were subjected to repeated blocks of a variety of complex strain histories and the resulting stress-strain responses determined. A new damage equation, based on simple materials properties, was then applied to stabilized blocks and a fatigue life predicted. The method entails a reversal-by-reversal stress-strain analysis of a history using the ratio of plastic to elastic strain range as a damage parameter. A computer program was developed to perform the detailed data reduction and analysis and can be employed on-line in a computer interfaced, closed loop test system. Agreement between experimental and predicted lives is within a factor of two over the range of lives investigated.

    Keywords:

    fatigue (materials), damage, predictions, strains, plastic (deformation), stresses, steels


    Paper ID: STP38032S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP38032S


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