Lightweight Optimum Design Of Electric Light Truck Frame Based On Bionic Principle

Automobile lightweight technology can significantly promote energy saving,emission reduction and consumption reduction of fuel vehicles,and enhance the cruising range of pure electric vehicles.It has become the core technology concerned by governments and automobile enterprises all over the world.Due to the single material and low degree of light weight,domestic commercial vehicles are 10%-15% lighter than similar vehicles in developed countries,so it has huge lightweight requirements.However,as for the commercial vehicles optimization,the farthest potential lightweight cannot be realized.Regarding the issue above,bionic design,finite element simulation,theoretical calculation and DOE test design are used to study the lightweight of electric light truck frame.The research results have certain theoretical value and engineering practical significance for promoting the lightweight design of vehicles.The main research contents of this thesis are as follows:(1)It is found that the bending and torsional cross-section coefficients of thin-walled hollow closed section are larger than those of solid section,based on the theoretical calculation of material force.It is verified that different parts of bamboo pole cross-section have different contribution to the overall stiffness,based on Optistruct,which is related to the tangent angle between wind load and stress point.It is verified that the elliptical weight-reducing hole can improve the torsional stiffness of the beam under the same weight-reducing condition,based on Optistruct.That is to say,thin-walled hollow closed section,unequal thickness closed section and elliptical weight-reducing hole have high stiffness characteristics.(2)The biological characteristics of high stiffness are applied to the design of square cross-section beams.And under different cross-section areas,the variation trend of torsion coefficient of square cross-section with cross-section parameters is further studied.The results show that the torsion coefficient of the cross-section increases first and then decreases with the increase of cross-section width when the cross-section area,bottom thickness and side thickness of the beam are fixed,and there is a maximum point.The torsion coefficient of the cross-section decreases with the increase of the side thickness when the cross-section area,bottom thickness and width of the beam are fixed.Based on them,a fast design method for high torsional stiffness beams is proposed.(3)Based on sensitivity analysis,a fast design method of high torsional stiffness beams is adopted to re-design the key beams.And the optimization design of steel-aluminum hybrid frame is studied combined with orthogonal test and multi-objective genetic algorithm.The results show that under the premise of meeting the strength and bending stiffness,the weight is reduced by 8.43%,the torsional stiffness is increased by 3.37%,and the first-order frequency is increased by 13.94% compared to the original frame.And the frequency change is more gradual,which solves the problem of the sudden change of the frame's natural frequency.