SYMPOSIA PAPER Published: 01 January 1975
STP34791S

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

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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.

Author Information

Wang, SS
Massachusetts Institute of Technology, Cambridge, Mass.
Mandell, JF
Massachusetts Institute of Technology, Cambridge, Mass.
McGarry, FJ
Massachusetts Institute of Technology, Cambridge, Mass.
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Details
Developed by Committee: D30
Pages: 36–60
DOI: 10.1520/STP34791S
ISBN-EB: 978-0-8031-4667-9
ISBN-13: 978-0-8031-0366-5