Design And Application Of Zero Poisson's Ratio Honeycomb Structure

Environmental pollution has become one of the most serious environmental problems in the world,and with the increase of the total number of cars environmental pollution is further aggravated.Faced with such a grim situation,the automobile industry needs to be reformed.In addition to the development of new energy and intelligent vehicles,it is of great research significance and application value to improve the external aerodynamic characteristics of vehicles by using variant technology to improve the energy utilization efficiency of vehicles.Therefore,it is necessary to study the vehicle variant technology to improve the external aerodynamic characteristics.In this paper,we study the drag reduction performance of automobile based on morphing technology.Firstly,the morphing technology based on honeycomb structure is studied.The stress concentration problem of octagonal honeycomb structure is solved by smooth transition,and then the optimization parameters of the improved structure are obtained using genetic algorithm.Considering the bearing capacity and deformation capacity of the structure comprehensively,the optimization design model of multi-stiffness honeycomb structure is established by using topology optimization method.Then the equivalent parameters of the new honeycomb structure configuration are obtained by homogenizing method,and the deformation and bearing capacity of the equivalent structure are verified.Finally,the designed variant structure is applied to the rear end of the vehicle to realize the whole vehicle drag reduction.The main research of this paper is as follows:(1)Aiming at the stress concentration problem of the reference octagonal honeycomb structure,the reference structure is improved by rounding the corners,and the theoretical expressions of the equivalent Young's modulus and equivalent shear modulus are derived,which is verified by using finite element analysis.Finally,based on genetic algorithm,the optimal geometric parameters of the improved structure are obtained.The local stress is extracted by deformation analysis and then further verifies that the structure can reduce the stress concentration.(2)Considering the bearing capacity and deformation capacity of the structure,the optimization design model of multi-stiffness honeycomb is established and a new honeycomb structure is obtained.Different optimization configurations of honeycomb are obtained by changing constraint parameters.By using finite element analysis,equivalent Young's modulus and shear modulus of different configurations are obtained,Finally,using homogenization method the equivalent parameters of the honeycomb structure are obtained,which can be usedto verify the structure's deformation and bearing capacity.(3)The aerodynamic performance of the vehicle is analyzed based on the design of the new honeycomb configuration.By changing the vertical diffuser angle and lateral diffuser angle of the vehicle,the vehicle drag is reduced.By establishing the simulation model of the vehicle's external flow field,the drag coefficient of the vehicle under different parameters is obtained,and then the best morphing mode is obtained and the drag reduction effect of this mode is verified.