Research On Modeling And Optimization Design Method Of Functionally Graded Honeycomb

On the overall background of the wide attention and quick development of Additive Manufacturing(AM) Technology, aiming at the problems of product lightweight and complex structure modeling, this thesis studied the lightweight optimization design and modeling of a typical cellular structure-honeycomb structure from structure and material field, respectively. The Functionally Graded Structure(FGS) honeycomb and Functionally Graded Material(FGM) honeycomb were proposed(collectively referred to as functionally graded honeycomb in the thesis). The close integrations of generative design method with honeycomb structure modeling and topology optimization with FGM design will have significant role and research meaning in improving the efficiency of product design and product performance, reducing product weight and cost, expanding the application range of AM technology, promoting the popularization of AM and even the change of manufacturing and design concept.The main research contents of this thesis are as follows:1. FGS honeycomb wall-thickness design. The design concept of variable-thickness honeycomb structure that was called FGS honeycomb referring to FGM honeycomb was put forward. Through the parameter analysis of the regular-hexagon honeycomb structure, the conclusion that the relative density of each cell was related to the hole wall length, hole wall thickness and pore diameter was obtained. On this basis, the variable density topology optimization was improved by removing the penalty factor’s influence on the middle density, and then the FGS honeycomb design method based on density mapping of topology optimization was put forward.2. FGS honeycomb modeling based on generative design method. On the basis of the generation of homogeneous honeycomb structure plane main lines using the tangent method, the FGS honeycomb modeling process is studied based on generate generative design idea, and the generation of FGS honeycomb model was accomplished by using UG secondary development. Then a FGS honeycomb with a specific set of parameters was used to demonstrate the application of the proposed method, and to verify its feasibility. In addition, this FGS honeycomb model was finally manufactured by our 3D printer.3. FGS honeycomb optimizing. To analyze the influence of key factors(base circle radius and weighting factor) in the design process on the design result, the response surface model was established. On this basis, the concept of multidisciplinary design optimization(MDO) was used to transform the FGS honeycomb optimization problem into MDO problem including structural field and mechanics field. The MDO model was established, which was solved by setting up the collaborative optimization(CO) framework, and then the FGS honeycomb with optimal comprehensive performance(volume and flexural rigidity) was obtained. In addition, targeting the normal homogeneous structure honeycomb and the proposed optimal FGS honeycomb that had the same weight, the comparison and analysis of the flexural stiffness of the two structures were conducted through the finite element simulation in Ansys Workbench software to verify the effectiveness of the proposed method.4. FGM honeycomb modeling and material distribution optimizing. The modeling thought based on mapping from the material space to the geometrical space was put forward. Firstly the material space that indicated the material composition was defined, and then the corresponding geometric space could be determined from the mapping function of the space. Then by using the interpolation algorithm, the material information of the other parts could be calculated. After that, the overall expression of the model geometry information and material information could be finally realized. By this proposed method, the clarity of data representation was improved. The FGM gear model was used as an example to prove the feasibility and effectiveness of the proposed method, which was then used in the modeling of FGM honeycomb. Based on the analysis of the FGM performance parameters and according to the concept of the variable density topology optimization method, the optimization model of the coefficient of FGM material distribution function was established, which was solved to obtain the optimal material distribution in each FGM honeycomb unit.