Paper number 1346

PLY WAVINESS ON IN-PLANE STIFFNESS OF COMPOSITE LAMINATES

Cimini Jr., Carlos A.1, and Tsai, Stephen W.2

1Department of Mechanical Engineering, Federal University of Minas Gerais
Avenue Antônio Carlos, 6627 - Pampulha, Belo Horizonte, MG, 31270-901, Brazil
2Department of Aeronautics and Astronautics, Stanford University
Durand Bld., Room 381, Stanford, CA, 94305-4035, U.S.A.

Summary 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.
Keywords waviness, defect, effective properties.

Theme : Composite Structures ; Modelling

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