The Lightweight Research Of Once Molding Whole Body On The Low Speed Pure Electric Vehicles

Until today in development of automobile industry, ensuring traffic safety,reducing environment pollution and saving resources have become three majorproblems of the automotive industry needed to be resolved. In such a grim situation,the electrci car has received wide attention and became the focus of national research,and lightweight body of electric vehicles is an effective way to deal with this problem.Lightweight body is mainly realized in three ways through new structural design,new technology and new materials. In the body design of composite materials HDPE,once molding lightweight body design and manufacturing technology was proposed inthis paper. By a number of rotational molding experiments, the lightweight body ofelectric vehicle was got which met the needs of using. The main contents of this paperare:(1) Three-dimensional model of the car body is established, then the stress on thebody in four typical conditions was analyzed. The analysis results show that underfour conditions the body strength can meet the requirements of electric vehicles. Inaddition to individual regional stress is larger, the remainder stress value is low,material is abundance, there are lightweight potential.(2) Because the road excitation frequency is below2.08Hz, and to avoid thesensitive frequency of3Hz as the standard, the first few vibration modes of the bodywere controlled between7~16Hz through the modal analysis which showed that bodyavoided the resonace phenomenon. Then transient modal dynamic analysis of thebody calculated the maximum stress of body dangerous parts under transient load andthe stress response of the parts. The results show that the maximum stress remainedwithin the allowable stress range and body strength safety problem did not exist.(3) Based on the body model, the stiffness method was used for topologyoptimization of car body. According to the results of topology optimization, theelectric car body structure was improved. After improvement the body qualitydecreased6.69kg, accounting for8.94%of the initial mass, the maximum stress offour conditions and whole body torsional and bending frequency remained at theoriginal level which reached the design standards.(4) Producing rotational molding special mold, rotational molding experimentswere completed with HDPE as raw material. The results show that the body met the requirements of design and using needs.