Design And Additive Manufacturing Of Variable Density Honeycomb Structure Based On Hyperelastic TPU

Due to the close relationship between energy consumption,operational efficiency and weight in products such as spacecraft,aircraft,and automobiles,lightweight technology is often used in their components and is considered an important technology in the aerospace and transportation industries.Honeycomb structures have long been used for lightweighting due to their high strength-to-weight ratio.On the basis of the existing lightweight capability of honeycomb structure,this thesis further explores the structural optimization method,integrates the topology optimization technology,CAD modeling technology and additive manufacturing technology,develops a parametric modeling method for complex structures,and proposes a method for efficient design and manufacturing of high-performance honeycomb structure.Finally,variable density honeycomb structure based on hyperelastic TPU material is designed and manufactured.This honeycomb structure has the characteristics of high specific stiffness,high resilience rate and large modulus of resilience,which can play a great role in resisting deformation.The main work of this paper is as follows:(1)Analysis of in-plane mechanical properties of honeycomb structure.By finite element simulation and polynomial fitting,the equivalent elastic modulus model of uniform honeycomb structure based on Euler-Bernoulli beam theory was modified,and the shortcoming that the original model can only be applied under low relative density was improved.On this basis,the joints were creatively introduced into the analysis of mechanical properties of honeycomb structures,and a new equivalent elastic modulus model suitable for non-uniform honeycomb structures is proposed for optimal design.(2)Topology optimization design scheme of honeycomb structure.With maximum stiffness as the objective and relative density of elements as the design variables,the optimization design process of honeycomb structure and the implementation scheme of variable-density method were given.The geometric relationship between honeycomb structure and design domain were analyzed.Based on this,a method of describing cell envelope by concentric circles was proposed,and the optimization results of variabledensity method were transformed into the variable density honeycomb structures.(3)Modeling method and additive manufacturing for variable density honeycomb.The secondary development of UG realized the fast,automatic and parametric modeling of honeycomb structure,and solved the complex problem of variable density honeycomb structure modeling.The resilience of variable density honeycomb structure was enhanced by replacing common engineering plastics with TPU material,the optimum process parameters of TPU products manufactured by FDM equipment were studied,the problems of wire drawing and warping were solved,and honeycomb test samples for mechanical experiments were manufactured.(4)Simulation and experimental evaluation of in-plane mechanical properties of variable density honeycomb structures.By finite element simulation and mechanical experiments,the compression property,bending property and resilience property of the variable density honeycomb structure were studied respectively.The results show that the topological optimization design increase the specific compression stiffness and specific bending stiffness by more than 47.05% and 64.33% respectively,and the modulus of resilience by 41.37% and 69.88% respectively.TPU material increases the resilience rate of both honeycomb structures by more than 89.50%.It is proved that the honeycomb structure designed and manufactured has good resistance to deformation.