Research On Weight Reduction Of Hydrogen-fueled Electric Bus Body Frame And Analysis Of Crash Safety

With the rapid development of the Global Society,the pressure of energy supply,environmental protection and industrial sustainable development is increasing day by day,and the use of new energy public transportation is promoted,can solve the above contradictory problems to a certain extent.Hydrogen fuel cell bus uses hydrogen as the source of automobile energy,uses the inverse reaction of electrolyzed water to drive the motor,and the exhaust gas is pure water mist,thus realizing zero emission.Compared with other types of conventional buses,hydrogen fuel cell buses are less destructive to the environment,more efficient in energy conversion,less noisy and more convenient for daily maintenance,has Gradually developed into the research focus of the city bus.However,the fuel supply system of the hydrogen fuel cell bus still has some deficiencies compared with the traditional fuel bus.In order to make the performance of the hydrogen fuel cell bus meet the driving requirements,the configuration of the whole bus needs to be improved,this also leads to an increase in the overall mass of the vehicle.Among them,the optimization of body frame structure is an effective measure.This kind of measure can effectively reduce the quality of the whole bus,at the same time,it is very important to improve the mileage and power performance of the bus.In this paper,a three-dimensional model of FSQ6107 SC hydrogen fuel cell bus frame is built with CATIA software,the bus structure is simplified reasonably,and the body frame finite element model is built with Hyper Mesh software.The static analysis of the body under five typical working conditions such as horizontal bending is carried out to determine the position and specific parameters of the maximum stress and displacement in the frame,and to ensure that the stiffness and strength of the body meet the design and use requirements.The natural frequency and vibration mode of the free mode of the body frame are calculated,and the performance of the body frame structure is verified by comparison,this study provides a basis for the lightweight design and optimization of the body frame structure.Then,according to the symmetry of the hydrogen fuel cell bus skeleton and the similarity of the optimized items,the optimized components in the skeleton are grouped.Through the direct sensitivity and relative sensitivity analysis,the components which are not sensitive to the performance of bus frame but sensitive to its quality are selected.Radial basis function neural network(RBF)is used to establish the approximate model of Skeleton Mass,stiffness and modal frequency.Taking the torsion rigidity of the bus frame not less than 90% as the constraint condition,taking the thickness of the parts as the design parameter,using genetic algorithm to carry out multi-objective optimization,the weight of the bus frame decreases from 2609 kg to 2388 kg,and the weight is reduced by 211 kg,the weight of the bus frame is reduced by 8.08%,the weight loss effect is remarkable.Finally,the simulation test of rollover and 100% frontal collision is carried out.The results show that the values of roll-over,Collision Energy and intrusion of all measuring points meet the safety requirements of passengers and the system.For the frontal impact of passenger cars,the analysis results show that the front seat of the driver after the impact deforms greatly,and most of the energy generated by the impact is absorbed by the front circumference and the cockpit,the deformation of the bus cabin intrudes into the driver's living space and the high-pressure hydrogen storage system(the value of the intrusion is small).Therefore,there is a risk of damage to the passengers and the high-pressure hydrogen tank,so the front structure of the bus needs to be improved and optimized,that is,the stiffness of the front end material should be strengthened or the energy absorbing structure should be added in the front wall to reduce the intrusion of the front end after collision,thereby reducing the risk of crew and system damage.The acceleration curve peak value is small(maximum 30g)and the deformation is reasonable.It is proved that the risk of occupant and system damage is small and the safety meets the design and operation requirements.