Topology Optimization Of Heterogeneous 3D Lattice Bio-inspired Functional Structures With Stiffness/Damping

Multi-functional design of lattice structure is an important research direction of aircraft structure design at present.The integrated design of load/damping is a difficult problem in aerospace equipment structure design.Light-weight lattice structure has many excellent properties,such as high toughness,impact resistance,sound absorption,electromagnetic wave absorption,effective thermal insulation and so on.It has a very wide application prospect.In the field of aerospace,many researchers pay attention to it.The lattice structure has been extensively studied by researchers all over the world.However,the lack of integration of lattice structure optimization algorithms with existing structures,less research on heterogeneous three-dimensional lattices and less research on topology optimization methods of heterogeneous lattice optimization seriously restrict the application and development of lattice structure.To solve these problems,this paper aims to study a design and optimization method for lightweight and multifunctional lattice structures.A heterogeneous three-dimensional Kagome lattice bionic functional structure was designed and fabricated,and its stiffness and damping characteristics were studied and optimized.Experiments show that the three-dimensional heterogeneous Kagome lattice bionic functional structure has excellent stiffness and damping characteristics.The main work of this paper is as follows:1.Inspired by biological tissues,the stiffness/damp heterogeneous lattice principle model is designed.Several applications of heterogeneous functional structures and similar engineering examples of ordered structure and functional material combination in nature are summarized.The design of heterogeneous three-dimensional lattice bionic functional structures filled with viscoelastic materials in ordered three-dimensional lattice structures is proposed.Plan.The polyurethane viscoelastic solids were prepared by prepolymer method using polyurethane as filling viscoelastic solids.The preparation scheme of polyurethane viscoelastic solids filled with 3D printed ordered structure was determined.The Kagome structure,which is often used in spacecraft design,is chosen as the selected ordered structure.The design parameters of Kagome structure are determined by calculation and analysis of the literature.2.Aiming at the optimization technology of specific stiffness of lattice structure,the solid isotropic material penalty model(ASIMP)based on material increase is proposed,and the complete mathematical model and optimization process of this method are established.The basic idea of ASIMP is to add materials to the inadequate parts of a given structure to obtain the optimal results.In this paper,ASIMP method is used to optimize the specific strength of three-dimensional Kagome structure.In order to evaluate the effect of the topological algorithm,the original three-dimensional Kagome structure and the optimized three-dimensional Kagome structure are fabricated by using 3D printing technology.Compression test results show that the specific strength and stiffness of the optimized three-dimensional Kagome structure are increased by 11.6% and 8.8% respectively compared with the original three-dimensional Kagome lattice.3.Aiming at complex modal calculation technology of complex heterogeneous viscoelastic lattice,a complex modal calculation method of complex heterogeneous viscoelastic lattice based on window function is proposed.Through window function filtering,the frequency is segmented so that the viscoelastic material damping matrix and stiffness matrix in the transfer function change from variable to constant,thus improving the calculation efficiency.Experiments show that the complex modal calculation method of complex heterogeneous viscoelastic lattice based on window function can calculate complex modal calculation of complex heterogeneous viscoelastic lattice quickly and accurately.4.For heterogeneous lattice bionic functional structure topology optimization technology,a heterogeneous structure topology optimization algorithm based on solid isotropic penalty model is proposed.The key problems of topology sensitivity,Lagrange function,topology flow and post-processing in optimization process are studied.The results of topology optimization under different material stiffness ratios are studied.It is found that when the Young's modulus of elasticity of the two materials differs greatly in heterogeneous three-dimensional lattice bionic functional structures,the results of heterogeneous lattice topology optimization are similar to those of single material topology optimization.Heterogeneous three-dimensional lattice bionic functional structures were fabricated using stainless steel and viscoelastic polyurethane solid materials.Static and dynamic signal analysis tests were carried out.The experimental results show that the heterogeneous three-dimensional Kagome lattice bionic functional structure has good stiffness and strength as well as good damping characteristics.