SYMPOSIA PAPER Published: 01 January 1975
STP34795S

Uniaxial Failure of Composite Laminates Containing Stress Concentrations

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Two previously developed failure criteria for predicting the uniaxial tensile strength of a laminated composite containing through-the-thickness material discontinuities (notches) are subjected to further experimental scrutinization. In particular, the two-parameter (unnotched tensile strength of the laminate and a characteristic length) models, which are capable of predicting observed discontinuity size effects without resorting to the concepts of linear elastic fracture mechanics, are based on limited experimental verification.

In the present paper, and experimental program is presented which examines the effect of changes in the material system, the laminate fiber orientations, and the notch shape and size (stress gradient), on the model predictions. This is accomplished by obtaining experimental data on two material systems, glass/epoxy and graphite/epoxy, in conjunction with two orientations of fiber-dominated laminates containing through-the-thickness circular holes and sharp tipped cracks of several sizes.

In addition to the test results, two observations based on the models are presented. First, the statistical failure distribution for a composite containing a circular hole is predicted using the models and shown to agree well with experimental observations. Second, an Irwin type correction factor applied to the stress intensity factor is shown to result in nearly constant values of the critical stress intensity factor for all values of crack length. The correction factor is shown to be related to the characteristic length of the present models.

Author Information

Nuismer, RJ
University of Utah, Salt Lake City, Utah
Whitney, JM
Air Force Materials Laboratory, Wright-Patterson AFB, Ohio
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Details
Developed by Committee: D30
Pages: 117–142
DOI: 10.1520/STP34795S
ISBN-EB: 978-0-8031-4667-9
ISBN-13: 978-0-8031-0366-5