Study On Mechanical Properties Of Cosine Function Cell-based Lattice Structure And Its Application In Vehicle Body Energy-absorbing Structure

With the intensification of energy crisis and environmental pollution,improving energy efficiency and reducing carbon emissions have become the urgent goals pursued by all countries in the world,among which the use of lightweight technology to reduce vehicle emissions is one of the important measures to achieve the above goals.The lattice structure has excellent mechanical properties,lightweight and energy absorption characteristics,which has a remarkable effect on realizing lightweight and improving crash safety of vehicles.However,the stress concentration of traditional lattice structures under impact load is obvious,which weakens their strength and load-bearing performance.Therefore,a novel Cosine Function CellBased(CFCB)structure with excellent mechanical properties was designed based on the traditional body-centered cubic structure.The deformation mechanism and equivalent mechanical properties of CFCB lattice structures are revealed through experiments,numerical simulation and theoretical research,and are applied to the design of vehicle energy absorption box to improve vehicle crash safety.Based on the national key research and development project(2021YFB2501705),this paper conducts relevant research on the mechanical characteristics of the novel lattice structure and its application in the energy absorption structure of automobiles.The main research contents are as follows:(1)Based on the traditional body-centered cubic structure,a novel CFCB lattice structure is designed.CFCB lattice structures with different structure parameters are prepared by additive manufacturing technology,and the quasi-static compression experiments are carried out.The deformation mechanism of CFCB lattice structure and the improvement effect of mechanical properties are revealed by comparing with the same mass body-centered cubic structure,and the influence of structure parameters on its deformation mode and mechanical properties is analyzed.(2)The mechanical properties of matrix materials are obtained by standard tensile test,and the finite element model of axial compression of CFCB lattice structure is established.CFCB lattice structure with different structural parameter combinations is designed,and the influence of different structural parameter combinations on its deformation mode and mechanical properties is analyzed,and the deformation energy-absorption mechanism of CFCB lattice structure under compressive load is further revealed.(3)Based on the deformation mechanism of the linear elastic stage of the cell member and the theory of Timoshenko beam,the equivalent elastic modulus and Poisson’s ratio theoretical analysis models of CFCB lattice structures are constructed.The platform stress prediction model of CFCB lattice structure is established based on the deformation mechanism of cell member in plastic buckling stage and the law of conservation of energy.The experimental and numerical simulation results are used to verify the theoretical model.(4)The CFCB lattice structure is filled into the simplified rectangular thin-wall energy absorption box,and the crashworthiness of the original energy absorption box is compared.Then,taking the diameter of the bar and the amplitude of the cosine function as the design variables,the multi-objective discrete robust optimization design of the CFCB lattice filled energy-absorbing box is carried out considering the influence of uncertainties in design and manufacturing.The optimized lattice structure filling energy absorption box is integrated into the vehicle,and the effect of improving the vehicle crash safety performance is analyzed.