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Load-end-shortening (stress, strain) curves for an axially compressed laminated composite test specimen with wavy layers (plies)

FROM:
Cimini Jr., Carlos A. (1), and Tsai, Stephen W. (2)
(1) Department of Mechanical Engineering, Federal University of Minas Gerais Av. Antônio Carlos, 6627 – Pampulha, Belo Horizonte, MG, 31270-901, Brazil
(2) Department of Aeronautics and Astronautics, Stanford University Durand Bld., Room 381, Stanford, CA, 94305-4035, U.S.A.

“Ply waviness on in-plane stiffness of composite laminates” (publisher and date not given in the pdf file. Latest reference is dated 1996)

ABSTRACT: A model was developed to determine the effect of ply waviness on the in-plane stiffness of composite laminates. On this model, plies containing waviness were mathematically described as in-phase sine-waves. Several configurations were included as well as generalization for any symmetric lay-up. The effective properties were calculated using both weighted average and springs in series approaches. A test program was conducted to validate the model for quasi-isotropic lay-ups. Data from the literature was also compared to model predictions for unidirectional and cross-ply laminates. These predictions correlated fairly well to test data. Model can be used as part of a framework to quantitatively access the effects of regions containing ply waviness on the global in-plane stiffness of structural composite parts. This information can be used to control quality or to impose operational limitations on such parts.

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