The Structure Design Of Reconfigurable Folding Skin Based On Origami Technology

Morphing aircraft can change its aerodynamic layout according to the external environment to maintain optimal flight performance throughout the flight,which is one of the important development directions of aircraft in the future.When the shape of the wing of the morphing aircraft changes,the skin is also required to deform,which is a major challenge to the airtightness,deformability and load-bearing capacity of the skin.The development of morphing skin technology is the key to the breakthrough of morphing aircraft.Morphing skin technology requires that the skin has sufficient out-of-plane bearing capacity to withstand the aerodynamic loads during flight,and at the same time it needs to have certain in-plane deformation capacity to ensure that the shape of the wing can change.Aiming at the problem that the current wing skin cannot meet the requirements of deformation and load-bearing performance,this paper proposes the idea of designing a new type of morphing skin based on the Miura-Origami.The skin is composed of MiuraOrigami structural units and is a multi-body system model.Each Miura-Origami structural unit can undergo in-plane bending deformation and rigid rotational displacement.When the skin is greatly deformed,it will eventually be converted into the superposition of the in-plane bending deformation and rigid rotational displacement of the Miura-Origami unit;when the rigid rotational displacement of the Miura-Origami structure is limited,the skin will have sufficient bearing capacity.In this paper,the theoretical model of Miura-Origami hinged multi-rigid-body system and the finite element model of Miura-Origami hinged multi-body system are established.Based on the theoretical model,the relationship between Miura-Origami's characteristic side length,Poisson's ratio,equivalent structural stiffness and MiuraOrigami's element geometric parameters and folding state is derived.And the theoretical analysis results are basically consistent with the finite element simulation results,confirming the rationality of the theoretical model of the Miura-Origami structural hinge multi-rigid-body system.In addition,based on the non-periodic Miura-Origami unit,this paper establishes a theoretical model of the Miura-Origami structure of the non-uniform curvature surface,realizes the parametric modeling of the Miura-Origami structure of the target surface of any single curvature,and compiles ABAQUS Python secondary development scripts to achieve the establishment of finite element models of MiuraOrigami skin with non-uniform curvature surfaces.The influence of Miura-Origami unit geometric parameters on the mechanical properties of Miura-Origami skin was analyzed by finite element simulation.The simulation results show that the Miura-Origami skin structure can be rendered anisotropic by adjusting the geometric parameters of MiuraOrigami unit.So that the skin has both out-of-plane bearing capacity and in-plane deformation capacity.Finally,this paper performs 2D and 3D CFD simulations of conventional skin and Miura-Origami skin wings respectively.The effects of the size of the Miura-Origami unit and the angle of attack of the wing on the pressure distribution and aerodynamic characteristics of the wing are analyzed under the conditions of 0.1Ma low-speed incompressible flow field and 0.6Ma high-speed compressible flow field.The simulation results of the 3D flow around the wing show that,compared with the 0.6Ma high-speed incompressible flow field,the Miura-Origami skin under the 0.1Ma low-speed compressible flow field causes a small loss of aerodynamic benefits of the wing,about 1%.This means that Miura-Origami skin is a morphing skin more suitable for low-speed flight.