Topology Optimization-based Design Of Face-centered Cubic Lattice Structure Without Vertical Rods

Lightweight design has become an important means to reduce energy consumption and pollutant emissions.Lattice structure has been widely used in lightweight design of structures because of its advantages of light weight,high specific stiffness and high specific strength.However,at present,the lattice structure design is mostly pre-designed before use,and there are still shortcomings in matching design according to the actual stress conditions of the cell,and there is still room for lightweight design.Therefore,this paper proposes a lattice structure design method based on topology optimization method and a gradient lattice filling strategy.The main work is as follows:(1)A multi-load and multi-constraint optimization model suitable for different working conditions was established,and the variable density method was selected to optimize the structure.Taking the maximum stiffness of the structure under load as the objective function and the volume fraction retained after optimization as the constraint,the mathematical expression of multi-load and multi-constraint topology optimization based on topology optimization method was obtained.Based on this formula,a design method of lattice cell structure adapted to the stress condition was proposed,and a new type of face-centered cell structure without vertical bar under compression condition was constructed.Compared with the traditional face-centered cubic cell structure,the compressive strength and equivalent elastic modulus of the face-centered lattice structure without vertical rods were 152% and100% higher respectively.(2)The theoretical model of relative density and equivalent mechanical model of a novel face-centered cell structure without vertical rods were established,and the influence of the dimensions of beams and rods on the volume fraction and structural strength of the new cell structure was studied.The 3D printing preparation,quasi-static compression test and finite element mechanical simulation analysis of the new cell structure were completed,and the principle of determining the optimal dimensions of beams and rods was given.(3)Based on the topological optimization algorithm,a novel vertical rod-free facecentered cell structure was used as the filling medium,and a gradient lattice cell filling method was proposed.According to the stress distribution relation of macroscopically optimized structure,this method fills lattice cells with different volume fractions correspondingly.Taking the simply supported beam model as an example,the design of lattice gradient filled structure and the verification of compression test were completed.It is found that the elastic modulus of the optimized structure is 145% and 16% higher than that of the conventional uniform lattice and topology optimized solid structure,respectively.