Mechanical Characterization And Optimization Of Auxetic Honeycomb Sandwich Structure Under Thermo-Mechanical Coupling

The honeycomb sandwich structure with excellent mechanical properties has been widely used in aerospace,automobile and sports and other fields.Among many kinds of honeycomb materials,negative Poisson's ratio honeycomb materials are widely used in the aerospace field due to their excellent mechanical and physical properties.When the negative Poisson's ratio honeycomb structure is subjected to complex load conditions,a light-weight structure with optimal mass distribution under some given constraint conditions is pursued.In this paper,a method of sundomain sizing optimization is proposed for the negative Poisson's ratio honeycomb sandwich structure and the wing rudder structure under the thermo-mechanical coupling load.The light-weight wing rudder structure which satisfies the requirements of stress,displacement and geometry is obtained,which may guide the design of the wing rudder structure in engineering application.Firstly,the classification,application and development of hone ycomb materials are introduced.Several negative Poisson's honeycomb materials with different topology geometries are introduced,especially the re-entrant hexagonal negative Poisson's ratio honeycomb structure.The domestic and aboard research status of mechanical properties and structural optimization design for re-entrant hexagonal honeycomb structures are introduced.Secondly,the equivalent elastic modulus and Poisson's ratio in the X and Y directions of the re-entrant hexagonal negative Poisson's ratio honeycomb cell structure are deduced by the Castigliano second theorem.The bending stiffness is obtained by using honeycomb sandwich structure cell model applying the periodic displacement boundary condition in finite element software ABAQUS.The influence of the geometry size on the bending stiffness of the honeycomb material is analyzed.Thirdly,parametric modeling of the negative Poisson's ratio honeycomb sandwich structures are carried out by using APDL assembly language of ANSYS.A sub-domain sizing optimization is used to calculate an optimal structure under temperature and three-point bending load,where the requirements of stress,displacement and geometry constraint are satisfied.Fourthly,the method of sub-domain sizing optimization is applied to enhance the flexural stiffness of the negative Poisson's ratio honeycomb sandwich structure,in which the maximum stress and displacement can not exceed the allowable value.The optimal structures are manufactured by using 3D printing resin.The three-point bending experiments are carried out to verify the optimization results.Finally,the sub-domain sizing optimization method is applied to find lightweight wing rudder under the thermo-mechanical coupling load.The lightest weight of wing rudder structure satisfies the constraints of stress,displacement and geometry,which can guide the wing rudder structure design in engineering application.