STP568

    Failure Mechanisms in Composite Plates Impacted by Blunt-Ended Penetrators

    Published: Jan 1975


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    Abstract

    Tests of 0–90° ply fiberglass roving-epoxy plates, impacted by hard steel cylindrical penetrators, have revealed a sequential delamination mechanism, especially well developed in plates having more than one layer of fibers in each unidirectionally reinforced lamina. In these plates the sequential delamination mechanism was the principal mechanism of spreading the deformation to parts of the plate distant from the impact point.

    In impacts by a cylinder of radius R, at moderate velocities such that the shear cut-out of a plug does not extend all the way through the plate, the sequential delamination is begun when a strip of width 2R of the first lamina is pushed forward by the penetrator, initiating two shear cracks through the thickness of the lamina parallel to the fibers of the first lamina. This strip in turn loads transversely the second lamina and initiates a separation between the first two laminas. This interlaminar crack spreads until it is stopped by the cutting-through of the loading strip by the penetrator. The process is then repeated by the second and third laminas, followed by the third and fourth, and continues through the thickness of the plate, with each subsequent delamination covering a larger area than the one before it.

    Other failure mechanisms in composite-plate perforation are also discussed, especially fiber stretching and tensile breaking. Recommendations for further analytical and diagnostic testing are made.

    Keywords:

    composite materials, fiber composites, penetration, impact, dynamic loads, delaminating, damage


    Author Information:

    Cristescu, N
    Graduate research professorprofessor, University of FloridaUniversity of Bucharest, Gainesville, Fla.

    Malvern, LE
    Professors, Engineering Science, Mechanics and Aerospace Engineering, University of Florida, Gainesville, Fla.

    Sierakowski, RL
    Professors, Engineering Science, Mechanics and Aerospace Engineering, University of Florida, Gainesville, Fla.


    Paper ID: STP33155S

    Committee/Subcommittee: D30.02

    DOI: 10.1520/STP33155S


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