STP995V1

    An Anisotropic, Damage-Coupled Viscoplastic Model for Creep-Dominated Cyclic Loading

    Published: Jan 1988


      Format Pages Price  
    PDF (344K) 22 $25   ADD TO CART
    Complete Source PDF (9.5M) 22 $140   ADD TO CART


    Abstract

    There are many practical applications in the power and propulsion industries that involve sustained periods of loading at high temperatures with periodic unloading-reloading sequences. Such histories may often be regarded as creep-dominated when only a small number of unloading-reloading events occurs over the life of the component. Typically, thermal constraint additionally results in rotation of the principal stress axes with respect to fixed material axes in regions of stress and temperature gradients, such as nozzle inlets. This rotation may produce anisotropic states of both creep damage and inelastic deformation. Such rotations also occur in the creep zone for an advancing creep crack or if far-field tractions change nonproportionally. In this paper, a continuum creep damage approach is coupled with a rate-dependent bounding surface theory to correlate nonproportional, axial-torsional experiments conducted on thin-walled tubular specimens of Type 304 stainless steel at 593C. A directionally dependent scalar damage distribution evolves as a second-order, symmetric tensor for each unique set of principal stress axes for this material, based on quantitative metallographic assessment of the damage distribution. A general higher order symmetric damage growth law is also introduced.

    Keywords:

    multiaxial testing, creep, cyclic plasticity, nonproportional creep, damage mechanics, fracture mechanics, nonlinear fracture mechanics


    Author Information:

    McDowell, DL
    Associate professor, graduate student, and graduate,

    Ho, K-I
    Associate professor, graduate student, and graduate,

    Stalley, J
    Associate professor, graduate student, and graduate,


    Paper ID: STP26776S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP26776S


    CrossRef ASTM International is a member of CrossRef.