STP1253

    Modeling of Thermomechanical Fatigue in (0/±45/90)s Sigma/TIMETAL 21S Laminates

    Published: Jan 1996


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    Abstract

    Micromechanical modeling is employed to evaluate the stresses and strains in laminated composite plates reinforced by elastic fibers in a thermo-viscoplastic matrix. Loading is limited to uniform in-plane stresses and to uniform changes in temperature. The local fields and macroscopic response of the plies are estimated with the transformation field analysis method that utilizes overall elastic properties and transformation influence coefficients derived from the Mori-Tanaka model. Fiber debonding and sliding are modeled by modifying certain fiber elastic moduli. This methodology, incorporated in a finite element scheme, is applied in simulations of hot isostatic pressing and subsequent loading of a (0/±45/90)s Sigma/TIMETAL 21S laminate. Axial tension/tension stress cycles are applied at constant temperature and in-phase cyclic temperature changes. The results show that the inelastic deformation of the matrix, assisted by extensive fiber debonding in the off-axis plies, promotes stress transfer to the fibers in the 0° plies. Under repeated loads, the fiber stress increases gradually at a certain rate and the laminate fails when the fiber ultimate strength is exceeded.

    Keywords:

    titanium matrix composites, laminates, fabrication, fatigue (materials), micromechanics, viscoplasticity, damage (materials), titanium, life prediction, titanium alloys, modeling


    Author Information:

    Bahei-El-Din, YA
    Professor, Cairo University, Giza,

    Dvorak, GJ
    William Howard Hart Professor of Mechanics, Rensselaer Polytechnic Institute, Troy, NY

    Nigam, H

    Wafa, AM
    Research scientist, General Electric Corporate Research and Development, Schenectady, NY


    Paper ID: STP18230S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP18230S


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