Research On The Bus Body Structure Safety Based On Offset Collision

With the development of the national economic strength,the number of road passenger cars is increasing,which leads to more and more traffic accidents.Among all kinds of traffic accidents,the frontal collision is the largest,probably account for 30%~50%,while the frontal collision is dominated by offset collision.In order to reduce the casualties,the safety of the bus body structure is essential,but at present there is no standard for the evaluation of the safety of passenger car frontal crash safety.Therefore,it is significant to study the frontal crashworthiness of passenger car,which can not only guide the design of the car body,but also help to develop the relevant standards.In this paper,a three-dimensional model and finite element model of a 6120 bus are established.According to the requirements of E-NCAP,a 100% bus frontal collision model is established,and the stability and effectiveness of the model are verified.According to the requirements of C-NCAP,the bus,the 20%,30%,40%,50%,and 60% overlap ratio of five buses in the left side of the bus are established.30km/h is chosen as the initial velocity of collision.By comparing the characteristics of the acceleration of the left B column,the energy response characteristics,the energy absorption of the key assembly,the structural deformation of the vehicle body and the driver's living space,the change rule was obtained.Results show:(1)At the 40% overlap rate,the peak value of the acceleration of the X direction of the left B column is the largest,and the rate of the 30% overlap is the second.(2)The energy absorption ratio of the front frame and chassis of the body is the maximum at the 40% overlap rate,the 30% overlap rate is the second.It is shown that the main energy absorbing members of the left side need to be deformed to meet the requirement of energy conversion at the two overlapping rates.(3)In the 30% overlap rate,according to the evaluation index of the selected six drivers,we can see that the driver's living space invasion is the most serious,and the overlap rate of the 40% is the second.In order to study the safety of the first passenger on the right side of the bus,the 20%,30% and 40% overlap rate bus collision models with the right side of the bus are established.Similarly,30km/h is chosen as the initial impact velocity,by comparing the B column acceleration properties on the right side of the vehicle,energy characteristics,key energy absorbing body assembly,structure deformation and the first row of the right side of the passenger space response,find the change rule.Results show:(1)At the 30% overlap rate,the peak acceleration of B column in the X direction is the highest,and the injury rate is relatively high.(2)The energy absorption ratio of the front frame and chassis of the body is the maximum at the 40% overlap rate,the 30% overlap rate is the second.(3)When the overlap rate of 20% and 30%,according to the evaluation index of the selected four indicators of the right side passengers living space of the first row,the passenger's leg space invasion is more serious.In view of the offset collision on the left side,this paper focuses on the analysis of the collision safety of the 40% overlap rate,and improves the original model by adding the energy absorbing structure.In view of the offset collision on the right side,this paper focuses on the analysis of the collision safety of the 30% overlap rate.In order to solve the problem of serious deformation on both sides of the front end of the chassis,the impact energy is guided by adding longitudinal beams and diagonal braces on the bottom of each door to improve the original model.Finally,the influence of high strength steel on the collision safety is studied.Results show:(1)In the case of large overlap ratio of the left side,it is obvious to reduce the deformation of the front frame and chassis structure by adding the energy absorbing structure between the front frame and chassis.(2)In the case of small overlap ratio of the right side,from the right side of the first row of passengers living space indicators,by improving the front end of the chassis on both sides of the door structure,to enhance the living space is obvious.(3)It is better to improve the yield strength of the front and the chassis of the driving area to improve the stress concentration of the front frame and the chassis of the driving area.