Analysis of a Unidirectional, Symmetric Buffer Strip Laminate with Damage


A method of analysis capable of predicting accurately the fracture behavior of a unidirectional composite laminate containing symmetrically placed buffer strips is presented. The analysis is based on a materials modeling approach using the classical shear-lag assumption to describe the stress transfer between fibers. Explicit fiber and matrix properties of the three regions are retained and changes in the laminate behavior as a function of the relative material properties, buffer strip width and initial crack length are discussed. As an example, for a notch (broken fibers) in a graphite/epoxy laminate, the results show clearly the manner in which to select the most efficient combination of buffer strip properties necessary to arrest the crack. Ultimate failure of the laminate after crack arrest can occur under increasing load, either by continued crack extension through the buffer strip, or by fiber breakage in the undamaged half-plane. That is, for certain choices of relative material properties and width, the crack can jump the buffer strip. For some typical hybrid laminates it is found that a buffer strip spacing to width ratio of about four to one is the most efficient. © 1984.


Mechanical and Aerospace Engineering

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Article - Journal

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© 1984 Elsevier, All rights reserved.

Publication Date

01 Jan 1984