ISSN: 0884-6804
Page Count: 8

Scaling of First-Ply Failure and Strength in [+ϑⁿ/−ϑ/−ϑⁿ/90/90²ⁿ]^s Laminates: Experiments and Predictions
Lavoie, JA
Composite structures design and analysis consultant, Virginia Polytechnic Institute and State University, VA

Morton, J
Director, Defence Evaluation and Research Agency,

Abstract

An experimental investigation of first-ply failure and strength was conducted on ply-level scaled carbon/epoxy composite laminates having a stacking sequence of [+ϑⁿ/−ϑ/−ϑⁿ/90/90²ⁿ]^s where the constraint ply angle, ϑ, was varied from 0 to 75°, and where the constraint ply angle, ϑ, was varied from 0 to 75°, and n varied from 1 to 4. First-ply failure was shown to depend on the level of constraint and the scale factor, n. The strain energy release rate for matrix microcracking was computed from first-ply failure data of the [0²/90²]^s laminate. Then, first-ply failure for all other layups was predicted using a numerical model that accounted for both constraint and size. Tensile strength was predicted using a strain energy release rate model for delamination of surface angle plies. A delamination energy value for each ply angle was calculated from the thinnest (n = 1) laminates to predict strength of the other sizes.

Keywords:
matrix cracking, first-ply failure, delamination, strength scaling, composite laminate

Paper ID: CTR10635J
DOI: 10.1520/CTR10635J
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