Research On Conceptual Design Of Vehicle Body Structure Based On Strain Energy Analysis

With the shortage of resources and environmental pollution serious increasingly,the disadvantages of traditional fuel vehicles begin to highlight,and electric vehicles become a better choice at present.In terms of electric vehicles,because their layout and structure are different from traditional fuel vehicles,it is necessary to study the body structure suitable for electric vehicles performance requirements,especially the optimization design of electric body structures in the conceptual design stage,which is directly related to the key performances such as the stiffness,NVH,crashworthiness.How to develop the required electric vehicle body structure,study the body structure concept design method and process for balancing weight and performance,and perform fast analysis and optimization the vehicle body to ensure the design quality,reduce the number of design modifications,improve the efficiency of research and development,shorten the research and development cycle is of great significance.In this paper,electric vehicle body is taken as research object,aiming to study its conceptual design method and application.The wireframe model of the electric vehicle body is discussed and established.The semi-rigid beam stiffness chain mechanical model of the vehicle body is established,and the flexibility characteristics of the joints are fitted by the agent model technology.An analysis method and theory based on the strain energy of the vehicle body structure is proposed,and the optimization of the main section with the constraints of bending,torsion,and modal performance indicators are realized,and the weight reduction and performance of the vehicle body structure are balanced.First,the structure characteristics of the modern electric vehicle body are analyzed,and the wireframe model of the body structure used in this paper is extracted and improved.A semi-rigid beam stiffness chain mechanical model that can be used to calculate the static and modal body is established using the transfer matrix method.Secondly,the Latin hypercube sampling method is used to extract vehicle body joint’s design variable samples.The spring set in the form of three tension springs and three torsion springs is used as a mechanical model to simulate the real joint.The Kriging method and radial basis function are used to fit the joint flexibility characteristics.So vehicle body joint’s flexibility can be predicted quickly.Then,the calculation method of strain energy is described,and the strain energy of the bending,torsion and first-order modal of the vehicle body structure is calculated.The overall and local bearing conditions of the vehicle body are analyzed,and the constraint index of the optimal design is proposed.At the same time,the working conditions of the full-width frontal collision and side collision are simulated with static loads,and the collision energy transmission path is analyzed using strain energy to verify the rationality of the vehicle body structure project.Finally,the minimum weight is taken as the target,the overall stiffness and local stiffness the first-order modal frequency,and the uniformity of the strain energy density of vehicle body are used as constraints for optimization.The main section parameters are optimized by genetic algorithm.Compared with the simulation results of vehicle body finite element model,the key index deviations are all within ±10%,which proves that the method proposed in this paper is accurate and reliable.Based on the research work in this paper,a main section library system with the main section as the core,set storage,edit,retrieval matching,calculation,analysis,and optimization is developed,which provided a comprehensive application platform for vehicle body concept design.