An Adaptive Structure Based on Hybrid Extension-Twisting Coupled Laminates
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AN ADAPTIVE STRUCTURE BASED ON HYBRID EXTENSIONTWISTING COUPLED LAMINATES
D. Cui and D. K. Li*
Keywords: interlayer hybrid, adaptive structure, extension-twisting coupled laminates, strength, optimum design Based on the classical laminate theory and proceeding from the necessary and sufficient conditions for the hygrothermal stability of materials, interlayer hybrid extension-twisting coupled free-layer laminates are designed. Then, analytical solutions for their yield and buckling strengths are derived. A mathematical model for the optimum design of composite structure is established to realize a synchronous multiobjective design of for interlayer hybrid extension-twisting coupled laminates. The finite-element method is used to simulate the hygrothermal effect, extension-twisting coupling, and buckling load of the laminates. Afterwards, an analysis of hygrothermal warping deformation and stiffness performance of the laminates is carried out to verify the suitability of the design method. Finally, the extension-twisting and bending-twisting coupled structures are constructed using the hybrid extension-twisting coupled laminates.
1. Introduction Extension-twisting coupled composites can be employed in many adaptive structures. For instance, the adaptive rotor structure of a tilt-rotor aircraft can be made using extension-twisting coupled laminates [1], which can spontaneously change the torsion angle of wing in order to achieve a higher hovering and propulsion efficiency. Such composites can also be used to manufacture the bending-twisting coupled adaptive wing of fixed-wing aircraft [2], which can effectively College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, 410073, China * Corresponding author; tel.: +86 0731-84573178; fax: +86 0731-84512301; e-mail: [email protected]
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 56, No. 5, pp. 881-904, SeptemberOctober, 2020. Original article submitted November 8, 2019; revision submitted June 4, 2020. 0191-5665/20/5605-0601 © 2020 Springer Science+Business Media, LLC
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z Fig. 1. Model of interlayer hybrid laminates. solve the aeroelastic deformation divergence problem of the wing and to improve its design performance and aeroelastic properties. At present, the majority of studies that focus on the extension-twisting coupled composites are mainly concentrated on single-fiber composites [3-5]. Although single-fiber composites possess a high design performance, the problem of their excessive cost is restricting its wide application [6]. Hybrid fiber composites can significantly reduce the material cost under the premise that the structure meets the reliability requirements [7], but the research on the structure of hybrid fiber composites does not consider its strength. In practical engineering, the hygrothermal stability of a material or a structure cannot be ignored [8, 9]. It has to b
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