Research On Topology Optimization Design Method Of Integrating Structures With Materialsconsidering Material Orientation Optimization

Structural lightweight design can effectively save resources,and topology optimization method is an important technical means to achieve lightweight design.Compared with the traditional macrostructure topological optimization,the integrated topological optimization design of structure and material can make the structure perfectly match its material,thus further improve the whole structural performance.However,in the process of structure and material integrated design,the resulted microstructural materials are usually anisotropic.Considering the material orientation optimization,the material utilization and the performance of structure can be further improved.In this context,based on the Bi-directional Evolutionary Structural Optimization(BESO)method,a topology optimization method of integrating structural and material design considering material orientation optimization is proposed in this paper.Firstly,based on in-depth analysis of previous research results,a hybrid stress and strain method is proposed to determine the optimal material orientation and the uniqueness of the optimal solution is also proved.It overcomes the shortcoming of “repeated global minimum” solutions which exist in the stress-based method and the strain-based method.In the concurrent design of structural topology and material orientation,the effectiveness of the proposed hybrid stress and strain method is verified by comparing with the stress-based method,strain-based method and energy-based method.Secondly,aiming to maximizing the structural stiffness,the material orientation optimization is introduced into the integrated topology optimization design of structures and materials.And a topology optimization method for concurrent design of structure,material and material orientation is proposed.The optimal material orientation is determined by combining the hybrid stress proposed above and strain method and the principle stress method,which can not only improve the computational efficiency,but also avoid the occurrence of “repeated global minimum”.At the same time,based on BESO method,the integrated design of macrostructural topology,material microstructural topology and material orientation are realized by constraining the material volume fractions of macrostructure and material microstructure,respectively.As a result,the stiffness of the structure is further improved.Finally,the integrated optimization design method of structural topology,material microstructure topology and material orientation is improved by replacing the macroscopic and microscopic material volume fraction constraints with a total structure mass fraction constraint,and the automatic distribution of "material" on two scales is realized by normalizing the macroscopic and microscopic sensitivities.On this basis,the improved integrated design method is extended to the structural dynamic design problem.The optimal macrostructure topology,material orientation arrangement and material microstructure topology characteristics are obtained,and the structural fundamental frequency is further improved.