Analysis And Improvement Research On Deformation Mode Of Front Structure In Bus Frontal Impact

With the rapid development of highway passenger transport,the safety of bus collision has been widely concerned by the whole society,and in the road traffic accidents of bus,the frontal impact traffic accidents of bus often cause significant property losses and casualties.At present,most of the collision safety research for buses adopts a general method similar to passenger cars,which does not fully consider the structural force characteristics of bus in the process of frontal impact,and in the aspect of body crashworthiness,it is usually adjusted according to engineering experience to adjust the layout form of the rod to optimize the collision resistance of the body structure,and there is a lack of corresponding theoretical research.The truss structure at the front end of the bus consists of a number of small section slender rod and oblique support,in the process of front collision,the bus mainly relies on the front-end truss structure to withstand and transmit the collision load.Unreasonable truss structure layout will lead to bending,plastic hinge and other large deformation of the rod and reduced crashworthiness of the body structure.Relying on the project of school-Enterprise cooperation to improve the crashworthiness of the bus,this paper puts forward a deformation pattern analysis method of the front structure of the bus based on the internal force analysis of the bus.By analyzing the internal force component of the main deformed rod,the cause of the large deformation of the rod is found.According to the analysis results,the structure of the front end of the chassis is improved,the load transfer path is redesigned and the deformation mode of the rod is improved,the phenomenon of bending,plastic hinge and the instability of the rod is avoided.On this basis,the material and size of the rod is optimized to improve the crashworthiness of the bus structure and control the collision acceleration.The CAE model of the frontal impact of the bus provided by the enterprise is established and verified in this paper.In order to improve the suction capacity of the energy absorption structure and reduce the maintenance cost after medium and low speed collision,the energy suction box is improved and the buffer block is added.On the basis of the front-end substructure of the chassis,the design of the front energy absorption structure based on the matching of different speed collision suction energy is carried out by orthogonal test method.The Designed suction energy structure is brought into the bus to verify the energy absorption effect of the suction energy structure.Combined with the basic principle of material mechanics,the internal force analysis method of space rod is proposed,and the internal force component of the section is deduced according to the stress analysis results of the rod unit.In the process of impact,in order to analyze the internal force components that cause large deformation of the chassis rod,the load of the first moment before the large deformation of the chassis structure is extracted,and the static analysis is applied to the structure of the chassis.Transforming dynamic analysis problem into static analysis problem.On this basis,a method for analyzing the deformation pattern of the front structure of bus based on the internal force analysis of rod parts is proposed.By analyzing the influence of each internal force component of the rod on the large deformation of the rod,the internal force component or combination that causes the deformation of the rod is finding,the internal force analysis of the rod in the joint near the large deformation rod is carried out at the same time,and the influence of other rod parts on the large deformation rod is analyzed.On the basis of the above analysis,the internal force analysis of other main rods of the front-end truss structure of the chassis is further analyzed,find out the force transfer path of the axial load.By analyzing the unreasonable structure of the front-end truss of the chassis,the causes of non-axial loads are found out.In order to evaluate the improvement effect of structural deformation mode,a method for evaluating the deformation mode of rod parts is established.The corresponding structural optimization strategies are proposed for different types of rod parts at the same time;Aimed at the mismatch structure design,the front end structure of the chassis is optimized and improved by using the internal force analysis method based on the rod and the optimization strategy of the rod piece,the load transfer path is redesigned to reduce the non-axial load caused by large deformation of the rod and to improve the deformation mode of the rod parts,and nvestigate on main safety evaluation indexes of vehicle structure;On the basis of structural optimization,the wall thickness and material of the front rod are optimized,and the induction groove is opened in the front part of the driver to increase the energy absorption space in the front part of the bus,and the energy absorption of each component is reasonably matched,so that the deformation mode of the member is more reasonable,finally,the crashworthiness of the bus body structure is improved.The research method in this paper is closely combined with the structural characteristics of the bus,not only suitable for the frontal impact condition of bus,but also suitable for other types of collision patterns,which provides a new idea for the optimal design of passive safety structure of buses,and has certain engineering application value.