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Book ChapterDOI

Design of a Flow Control Device Using a Special Class of Hybrid Symmetric Bistable Laminates in Clamped Boundary Condition

TL;DR: In this paper, a flow control valve is designed, exploiting the bistable characteristics of a special class of hybrid laminates made of glass epoxy and carbon epoxy prepregs.
Abstract: In this manuscript, a concept flow control valve is designed, exploiting the bistable characteristics of a special class of hybrid laminates made of glass epoxy and carbon epoxy prepregs. The principal structural element of the device is a hybrid bistable laminate, having a multi-section layup laid in a symmetric configuration. The thermal curing process responsible for the inherent bistability is simulated in ABAQUS\(^{\textregistered }\) and the equilibrium shapes hence obtained using the FEA scheme is validated against an existing semi-analytical technique based on the Rayleigh-Ritz minimization of potential functional. These multi-stable elements are then studied for their potential in controlling a flowing stream. Toward that, the snapping response of these laminates in a flow stream is analyzed using a combination of XFOIL and ABAQUS\(^{\textregistered }\). The pressure distribution on the laminate is estimated using XFOIL, which is an interactive program for analysis of subsonic isolated airfoils in viscous/inviscid low Reynolds number flow. The pressure distribution hence obtained is used to evaluate the load-displacement characteristics of the laminate using post-buckling regime analysis capabilities of ABAQUS\(^{\textregistered }\). Using these analysis tools, the design space is explored and the possibility of using the proposed bistable design elements for flow regulation is established.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors investigated the snap-through characteristics of a special class of hybrid bistable symmetric laminate (HBSL) subjected to different loading constraints and imperfections.

19 citations

References
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Journal ArticleDOI
Michael W. Hyer1
TL;DR: In this paper, a theory explaining the characteristics of the cured shapes of unsymmetric laminates is presented, based on an extension of classical lamination theory which accounts for geometric nonlinearities.
Abstract: A theory explaining the characteristics of the cured shapes of unsymmetric laminates is presented. The theory is based on an extension of classical lamination theory which accounts for geometric nonlinearities. A Rayleigh-Ritz approach to minimizing the total potential energy is used to obtain quantitative information regarding the room temperature shapes of square T300/5208 (0(2)/90(2))T and (0(4)/90(4))T graphite-epoxy laminates. It is shown that, depending on the thickness of the laminate and the length of the side the square, the saddle shape configuration is actually unstable. For values of length and thickness that render the saddle shape unstable, it is shown that two stable cylindrical shapes exist. The predictions of the theory are compared with existing experimental data.

380 citations

Journal ArticleDOI
TL;DR: In this article, the shape functions that model the out-of-plane displacements of partially unsymmetric laminates are modified to include variations of the curvatures within the domain.

116 citations

Journal ArticleDOI
TL;DR: In this article, a novel type of embeddable variable stiffness elements exploiting thermally-induced multi-stability in unsymmetrically laminated composites is presented.

77 citations

Journal ArticleDOI
TL;DR: In this paper, the curvatures of the hybrid laminates can be doubled compared to pure unsymmetric CFRP laminate, due to the thermal contraction of the inner isotropic layer upon cool down from cure.
Abstract: The potential of using multistable composite materials for adaptive structures is currently receiving interest from the aerospace community because they possess more than one single equilibrium configuration. Unsymmetric CFRP laminates are studied which have an inner isotropic metallic layer. These hybrid laminates are studied using analytical, finite element and experimental techniques. The thermal contraction of the isotropic layer upon cool down from cure induces large in-plane thermal loads which act remotely from the laminate's neutral plane, increasing snap-through moments and out-of-plane displacements. The curvatures of the hybrid laminates can be doubled compared to pure unsymmetric CFRP laminates.

70 citations

Journal ArticleDOI
TL;DR: In this paper, a novel type of bistable hybrid laminate with symmetric lay-up is presented, which is doubly-curved and the two stable configurations have identical curvatures with opposite signs.

53 citations