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Abstract Flexible skin is an essential component of morphing wing and morphing wind turbine blade. The support structure of the flexible skin undergoing one-dimensional morphing is required of good in-plane morphing capability and good out-of-plane load-bearing capability as well as zero Poisson’s ratio. To overcome these problems, an accordion honeycomb with zero Poisson’s ratio was proposed as a potential candidate for support structure of one-dimensional morphing flexible skin. To comprehensively analyze the in-plane and out-of-plane elastic properties of the proposed structure, the equivalent elastic modulus in the x-direction and the equivalent shear modulus in the x-y plane were derived by the Castigliano’s second theorem considering the internal bending moment, axial force and shear force; the equivalent shear modulus in the x-z plane was determined by principle of minimum complementary energy and principle of minimum potential energy; besides, the equivalent elastic moduli in the y and z direction, and the equivalent shear modulus in the y-z plane were also obtained by conventional derivation methods. The theoretical formulas were then verified by finite element analysis in ANSYS. Finally, comparisons with several conventional theoretical models were carried out to show the superiority of the theoretical model adopted in this paper. Results show that theoretical formulas are of good agreement with finite element analysis, proving the validity of the derivation. Accordion honeycomb of lower in-plane stiffness and higher out-of-plane stiffness will be obtained by employing larger height ratio of inclined beam h, spacing ratio of inclined beam g, thickness ratio of vertical beam η, and smaller thickness ratio t. These results can be used for rapid predictions of the mechanical properties of the accordion honeycomb, providing corresponding reference for structural design of one-dimensional morphing flexible skin. Furthermore, the theoretical model proposed in this paper is more accurate and has a wider range of application on the analyses of similar cellular honeycomb structures than conventional models.
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Received: 17 August 2017
Published: 29 January 2018
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2018, Vol. 39 
