Analysis And Optimization On Frontal Crash Safety Of A Miniature Electric Car

Electric cars account for more than 60%in the new energy vehicles.Sale volume of the electric vehicles is growing faster and faster due to its advantage,but to traditional cars,it has its own problems.Firstly,due to the high mass of the battery system,electric cars are often much heavier than traditional cars.Research shows that with 10 percent lighter,energy consumption decreases 10 percent and the carbon emission decreases 5-6%.The energy dissipation and pollution with mass increase is against the original intention of the new energy car.Secondly,to electric cars,they have to both meet the crash safety requirements of traditional and new energy cars.Autoignition,short circuit and liquid leak had draw extra attention on the battery system.Now China's regulation on the crash safety of battery system is not very specified.People are paying more attention on the crash safety of the battery construction.At the third,manufacturers are tend to develop electric cars based on tradition cars which is not originally designed for electric car.That brings anther problems.Based on those condition,this article focused mainly on weight lightness,optimized the crash safety of a electric car which was developed from a traditional car.In this article introduced the research situation home and abroad,compared the electric cars crash safety regulation between China and other countries.Proposed the weakness and suggestion on China's regulation.Briefly introduced the basic theory of finite element method,design of experiment and optimization.Represented the method of building a vehicle finite element crash model.Built and verified the model.During the optimization,analyzed the crash safety performance at first,found the problem:front side member deformed undesirably with much less crumple,too much dash panel intrusion,deformation of floor,central channel and door frame.Aimed at the problems,firstly optimized the thickness of front construction.Primarily chose 10 front parts,used latin hyper cube to get the sample points.Computed the points and required the response by solver software.Taking the advantage of different approximation models built the first order response surface model for mass and Kriging model for the max acceleration of B-pillar and the absorbed energy.Filtrated 4 important components using significance analysis with much less computation cost.Then built more accurate model for the filtrated components.Acquired the optimal result using NSGA-? genetic algorithm,verified the credibility.At the second stage of the optimization,focused on the structure optimization of the front side member.In order to increase crumple,took out the enhanced panel,added two derivational grooves around the inner panel of the member which is 5mm deep and 30mm wide.The final optimization results showed that the mass of the car's front structure was decreased by 21%,absorbed energy increased by 16%and max acceleration decreased by 11.2%.The computation cost in this method is low.During the thickness optimization,used two steps to achieve the results.Decreased the computation cost with a tolerable accuracy level.When optimizing the front side member,changed no material and added derivational grooves which could be easily realized by craft and lowered the cost by disposing two enhanced panels.This research is of engineering significance for electric cars to lower mass and enhance crash safety.