| In recent years,with the continuous development of China’s economy and the increasing progress of people’s living quality,automobiles have begun to enter into millions of households.As a result,the sales of automobile products in China have risen sharply,leading to traffic congestion.With the rapid consumption of natural resources and the reduction of reserves,in addition to the car driving process,it will emit toxic gases from the tail,resulting in air pollution around.With the continuous improvement of population quality and awareness of energy saving and emission reduction,people are more and more concerned about the surrounding air problems,and how to solve the problem of automobile emissions has become the focus of attention.Therefore,advocating bus transportation and encouraging people to travel more by bus has been widely recognized by the society,and the bus transportation industry has become an indispensable transportation choice of the society.And the weight of the bus has a great relationship with the emission of the exhaust gas.By reducing the body quality,not only can we achieve the requirements of energy saving and emission reduction,reduce air pollution,but also can reduce costs and enhance competitiveness.In this paper,the body frame of a light bus is taken as the research object,the strength and stiffness of the whole body frame are analyzed,and the lightweight design of the whole body frame is carried out.The main research contents are as follows:In the process of researching the body frame,this paper uses the finite element method to build the analysis model from the beginning,simplify the model,extract the middle surface,divide the unit and check the quality,and then calculate the strength of the body under bending,ultimate torsion,emergency braking and emergency turning conditions.The results show that the strength of the body is calculated by the bender.Under working conditions,the maximum stress on the frame appears at the right rear eyebrow connection plate,its maximum stress is 117.5 MPa,its evaluation stress is 229 MPa,the material of the beam is HC340 LA,and its fatigue limit is 259 MPa.Under the ultimate torsion condition,the maximum stress on the frame appears at the lower left corner of the front windshield.The maximum stress is241.5 MPa.The evaluation stress is 279 MPa.The material of the beam is HC340 LA,and its yield limit is 370 MPa.Under the condition of emergency braking,the maximum stress on the frame appears at the cockpit floor,and its maximum stress is146.5 MPa.Its evaluation stress is 190 MPa.The material of the beam is DCO1.Its yield limit is 185 MPa,and its stress does not exceed 2.7% of the yield limit.Under the limit turning condition,the maximum stress on the frame appears on the right side connecting plate of the sixth cross beam with the seat installed before the leaf spring.The stress is 244.1 MPa,and the evaluation stress is 317 MPa.The material of the beam is SAPH 440,and its yield limit is 305 MPa.It can be concluded that the stress state of the modified body skeleton can meet the safety requirements under the above conditions.Then,the stiffness calculation under bending and torsion conditions,as well as the deformation of large body openings are analyzed.The structure characteristics of the car body are preliminarily grasped,which provides a reference for the product optimization and improvement work in the future.Finally,the principle of optimal design is discussed,and then the significance of sensitivity analysis is introduced.Then,the thickness of the plate is selected as the design variable,the change of bending stiffness and torsion stiffness as the constraints,and the minimum quality of the body skeleton as the objective function,and the optimization analysis model is established.After the solution of the finite element software,the sensitivity of each plate is obtained,and the lightweight design is carried out according to the actual requirements.Results The weight of the body was reduced by 72.39 kg from the original 1031 kg.The lightweight body decreased by 7.02%compared with the original one,which met the design requirements of lightweight.Finally,the stiffness under bending and torsion conditions before and after optimization and the strength under four conditions are verified.The results show that the displacement under bending conditions changes from-0.649 mm to-0.681 mm,changing by 4.7%,the torsion condition changes from-0.476 mm to-0.459 mm,changing by 3.5%.The change of bending and torsion stiffness meets the safety requirements of materials.The strength under four conditions meets the safety requirements of materials.The optimization scheme meets the requirement of lightweight design. |
PDF Full Text Request