STP1302: Creep-Fatigue Interaction in Delamination Crack Propagation of Advanced CFRPs at High Temperatures

    Uematsu, Y
    Assistant, Graduate School of Engineering, Osaka University, Osaka,

    Kitamura, T
    Associate professor and professor, Graduate School of Engineering, Kyoto University, Kyoto,

    Ohtani, R
    Associate professor and professor, Graduate School of Engineering, Kyoto University, Kyoto,

    Pages: 23    Published: Jan 1997


    Abstract

    The objective of this study is to elucidate creep-fatigue interaction in Mode I delamination crack propagation of polymers reinforced by carbon fibers at high temperatures. The materials tested are two unidirectionally reinforced laminates, AS4/PEEK (carbon fiber: AS4, matrix: poly-ether-ether-ketone) and T800H/PMR-15 (carbon fiber: T800H, matrix: polyimide). Crack propagation tests are conducted in cyclic loading conditions with and without hold(s) at maximum tension and zero load at 473K for AS4/PEEK laminates and 573K for T800H/PMR-15 laminates, respectively. In fatigue with high frequency, the crack propagation rate per unit cycle da/dN is correlated well with the stress intensity factor range ΔK. However, the crack propagation in AS4/PEEK laminates depends strongly on the load waveform, while that in T800H/PMR-15 laminates is independent of it. The crack propagation in AS4/PEEK laminates is accelerated by the tensile load hold due to the creep deformation of matrix and it is purely time-dependent. In the time-dependent crack propagation, the rate per unit time da/dt is correlated well with the stress intensity factor K at the hold. On the other hand, the time-dependent crack propagation is decelerated by the zero-load-hold because of the creep recovery of matrix.

    Keywords:

    delamination, crack propagation, high temperature, CFRP, poly-ether-ether-ketone, polyimide, creep, fatigue, creep-fatigue interaction, creep recovery


    Paper ID: STP11371S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP11371S


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