Research On The Topology Structure Of The Honeycomb Core

Smart morphing aircraft can change its shape and aerodynamic shape by morphing, according to the flight environment and its mission, which can achieve the optimal flight efficiency under different flight conditions. Smart morphing aircraft has the abilities of multitasking, multi-objective utilization, and improve flight radius because of saving energy, has become the most important next generation of aircraft research direction. Traditional rigid skin cannot adjust it shape and size to meet the of smart morphing aircraft morphing requirement, correspondingly. So the development of new type of flexible skin materials is imperative. Because the flexible skin material need to realize the flexible deformation, or even big super elasticity deformation, facing many problems as sensing, control and drive technology, new materials, new technology development, there is still no proper solution. In this study, the concept of flexible mechanism will be introduced to cellular structure sandwich material, and a super elasticity flexible skin based on the concept of honeycomb structure. And a super elasticity flexible skin of more safety and reliable, strong carrying capacity and lightweight, is expected to achieve large deformation smoothly. Honey comb core, which supports the face sheet when exposing to aerodynamic load, decides the performance of super flexible skin by its deformation capacity, deformation characteristics and bearing ability. In the premise of loads carrying capacity and lightweight, achieving honeycomb core large deformation strain flexibly and different topology design, decorating different mechanical properties of honeycomb according to the morphing demand, are the basis of the super elasticity flexible skin development.This research won National Natural Science Foundation Project (No.51075380) assistance. The purpose of this paper is to through the topology design improve the deformation flexibility and resilience of the honeycomb sandwich, make it adapt to the needs of the large deformation, the deformation characteristics of hexagonal honeycomb structure are summarized on the basis of the beam model and the deformation mechanism are discussed, the characteristics of a new hexagonal honeycomb, and the combination of positive and negative Poisson’s ratio hexagonal honeycomb are studied; A U-shape accordion honeycomb was designed and its deformation characteristics are analyzed in theory and the results were compared with experiment and Finite Element Method results; Finite Element Method was proposed to study a straight cell wall accordion honeycomb’s large deformation characteristics, maximum strain capacity and the topology optimization.Firstly, the smart morphing aircraft and its advantages were introduced, and the challenges of development smart morphing aircraft were analyzed. And the progress and challenges of super elasticity flexible skin were proposed and analyzed, and the honeycomb structure material developed super elastic flexible skin introduced analysis, expounds the source of the topic, the research significance and research difficulties and research methods. Expounded the source of the topic, the research significance, research difficulties and research methods.Secondly, On the basis of beam model, deduced the hexagonal honeycomb core’ s equivalent elastic modulus, Poisson’s ratio, and the maximum theoretical expression formulas. And the influence of parameter changes on the deformation characteristics of hexagonal honeycomb core was studied, and the deformation mechanism was discussed in this paper. Positive and negative Poisson’s ratio composite honeycomb sandwich structure was designed, which can realize Zero Poisson’s ratio of deformation features and Poisson’s ratio of distributed layout with hexagonal honeycomb core, and its deformation characteristics are analyzed.Thirdly, a U-shape accordion honeycomb core, which has a large deformation capability, was designed. Its equivalent elastic modulus was derived in the method of Energy Method, and its maximum strain was studied. The behalf unit was processed in65Mn, and the deformation characteristic was studied in experiment. And the experiment result shows the U-shape accordion honeycomb has a good capability of flexible deformation, which can meet the requirement of one dimensional skin. All results shows, U-shape accordion honeycomb core is a good scheme to one dimensional flexible skin.Fourthly, the large deformation characteristic of straight accordion honeycomb core was studied in FEM software ANSYS, the result shows honeycomb core’s equivalent elastic modulus changes with the strain, the reason is the topology nonlinear. And the maximum strain was calculated. At last, the straight accordion honeycomb core’s topology was put to optimize, which can be a good reference of honeycomb design.