STP593: Three-Dimensional Solution for a Through-Thickness Crack in a Cross-Plied Laminate

    Wang, SS
    Research associates and professor, Massachusetts Institute of Technology, Cambridge, Mass.

    Mandell, JF
    Research associates and professor, Massachusetts Institute of Technology, Cambridge, Mass.

    McGarry, FJ
    Research associates and professor, Massachusetts Institute of Technology, Cambridge, Mass.

    Pages: 25    Published: Jan 1975


    Abstract

    A three-dimensional solution is given to the problem of a through-thickness edge crack in a thin 90/0/0/90 laminate under uniform tension normal to the crack direction. The solution is obtained from a three-dimensional finite-element analysis based on the hybrid stress model, and formulated through the Hellinger-Reissner variational principle. The results indicate that the classical 1/√r stress singularity is maintained for the in-plane stresses which vary through the thickness and are discontinuous at the ply interface. The interlaminar shear and normal stresses also increase rapidly as the crack tip is approached; the interlaminar shear stresses are always maximum at the ply interface, while the interlaminar normal stress may be maximum at the interface or at the laminate center. The in-plane stresses follow a similar distribution and give an average through-thickness stress-intensity factor similar to two-dimensional predictions. The interlaminar stresses show a strong interaction of the crack tip singular and free-edge effects, as well as a strong influence of the degree of biaxiality of the in-plane stresses. The results suggest several aspects of subsequent subcritical crack extension.

    Keywords:

    fracture properties, composite materials, stress concentration, finite elements, stresses, crack propagation


    Paper ID: STP34791S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP34791S


    CrossRef ASTM International is a member of CrossRef.