Finite-Displacement Analysis of Laminated Composite Strips with Extension-Twist Coupling
Publication: Journal of Aerospace Engineering
Volume 9, Issue 3
Abstract
An analytical model for laminated composite strips exhibiting extension-twist coupling is presented. The analysis is developed first for flat laminates and subsequently extended to include finite pretwist. The displacement field is developed in three steps, each accounting for a kinematic contribution. A finite rigid-body twisting rotation is considered first. This is subsequently modified to include Saint-Vénant's type warping where the transverse normal and out-of-plane shear strains are neglected. Finally, inplane extension, shear, bending, and twisting curvatures are accounted for by superimposing a classical-type small-displacement field. Closed-form expressions relating applied extension to twisting rotation are obtained and the contribution of axial force to the twisting moment is isolated. Three approximate models are derived and the influence of the free-edge conditions and Saint-Vénant's assumptions are assessed. Based on this assessment, a simple two-parameter model accounting for the axial force contribution to the twisting moment is proposed. Comparisons of analytical predictions with a finite-element simulations for both flat and pretwisted laminates illustrate the accuracy of the developed models. A set of pretwisted laminated composite strips made of a graphite/cyanate material system is manufactured and tested. A custom-made apparatus designed to allow the laminate to twist freely under axial loading is used to measure the twist angle associated with applied axial force. Test results depict the nonlinear axial force-twist behavior and the analytical predictions are in close agreement with test data.
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References
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Information
Published In
Journal of Aerospace Engineering
Volume 9 • Issue 3 • July 1996
Pages: 80 - 91
Copyright
Copyright © 1996 American Society of Civil Engineers.
History
Published online: Jul 1, 1996
Published in print: Jul 1996
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