STP836

    Criticality of Disbonds in Laminated Composites

    Published: Jan 1984


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    Abstract

    Usefulness of analytical methodologies and nondestructive tests for assessing criticality of disbonds in laminated composties is examined. Fracture mechanics approach and critical energy release rate concepts are employed for the prediction of catastrophic growth due to quasi-static transverse shear loading. Semi-empirical growth laws are considered for modeling slow growth under cyclic loading.

    Brief descriptions of the analytical methods utilized for calculation of energy release rates are given. Sizes and locations of implanted disbonds in graphite/epoxy laminates are determined from ultrasonic C-scans. Analytical results and quasi-static destructive test data for beams subjected to three-point bending are correlated for determining the critical value of energy release rate. Effects of initial flaw size, location, sharpness of disbond tips, as well as mixed-mode (I and II) loading conditions are studied. Ultrasonic C-scans are also used for monitoring growth of disbonds in plate-type structures under cyclic transverse shear. Least square fits are attempted with the disbond growth rate data.

    Keywords:

    composite materials, fatigue (materials), laminated composites, nondestructive evaluation, defect criticality, delamination fracture, graphite/epoxy materials, fatigue crack growth, fracture mechanics


    Author Information:

    Chatterjee, SN
    Staff scientist, Materials Sciences Corporation, Spring House, Pa.

    Pipes, RB
    Professor and associate scientist, Center for Composite Materials, University of Delaware, Newark, Del.

    Blake, RA
    Professor and associate scientist, Center for Composite Materials, University of Delaware, Newark, Del.


    Paper ID: STP30203S

    Committee/Subcommittee: E08.01

    DOI: 10.1520/STP30203S


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