The Drapability of Aligned Discontinuous Fiber Composites

• Published in: Journal of composite materials 1997-03, Vol.31 (5), p.428-465
• Main Authors: Tsuji, Nobuyuki, Springer, George S., Hegedus, István
• Format: Article
• Language: English
• Subjects: Applied sciences; Composites; Exact sciences and technology; Forms of application and semi-finished materials; Polymer industry, paints, wood; Technology of polymers
• ISSN: 0021-9983; 1530-793X
• DOI: 10.1177/002199839703100501

The drapabilities of uncured unidirectional aligned discontinuous fiber composites were investigated, the drapability being defined as the ratio of the tip deflections, in one minute, of a discontinuous to a continuous fiber reinforced composite canti-levered beam. Equations were developed for calculating the deflections of such composite beams taking into account large deflections, and elastic and viscoelastic material behavior. On the basis of the model, a computer code was written which, for given fiber and matrix properties, discontinuous fiber geometry, fiber volume fraction, and fiber orientation, provides the stresses and strains in and the displacements of the composite beam, and the drapability. Tests were performed with beams made of uncured discontinuous and continuous fiber composites. Tip deflections were measured during the tests and were compared with tip deflections calculated by the computer code. Good agreements were found between the data and the results of the present model. Using the computer code, parametric studies were also conducted to assess the effects of fiber geometry, fiber volume fraction and fiber orientation on the drapability of uncured composites, and the effects of fiber geometry on the on-axis elastic moduli of discontinuous cured fiber composites. The results of these studies indicate that while discontinuous fibers increase the ability of uncured composites to drape, such fibers reduce the longitudinal modulus of cured composites.