Design Of Frontal Body Structure Based On Optimized Acceleration Curve Of Bus In The Frontal Crash

Buses bring convenience to people as well as serious traffic safety problems.In bus traffic accidents,the proportion of frontal crash accidents is the highest,which has promoted the attention and research of the people from all walks of life.Although the study of bus frontal crash in China started late,some domestic enterprises and researchers have carried out many experiments and research,and the relevant departments of our country are actively promoting the formulation of the bus frontal crash regulations.In this paper,we will study the relationship between the acceleration curve of the bus and the safety problem of the occupant,and on this basis,the improvement scheme of the front body structure is proposed to reduce the occupant injury.The first part is to study the effect of acceleration curve on occupant injury.Based on the regulations,GB 11551-2014 and GB 13057-2014,the frontal crash tests of four buses with 100% rigid wall barrier is carried out to obtain the acceleration curves and analyze the characteristics of the acceleration curves.Based on the acceleration curves of different characteristics,the sled tests are set up.And the influence of the different curves on the occupant injury is evaluated by the human injury criterion and the Weighted Injury Criterion.The orthogonal test is used to study the sensitivity of the characteristic parameters of different curves on the occupant injury,and the optimal curve is selected causing minimal damage to occupant.The results show that different body structures and energy absorbing devices of buses result in different body deformation and acceleration curves in frontal collision.According to the structural characteristics of buses and the study of optimum acceleration curve,the trapezoidal wave can be used as a simplified curve of the acceleration curve,and the wave peak in the simplified curve has the greatest influence on the sensitivity of the occupant injury and is positively related to the occupant injury.In the second part,aiming at improving the safety problem of buses,the front structure of buses is optimized based on the target acceleration curve.Combined with the finite element model of the whole vehicle,the frontal crash simulation is carried out.According to the optimal curve,the simplified curve and the target curve of the acceleration curve are determined.The target curve is translates into accelerationdisplacement curve,and the best energy absorption under the target curve is calculated.The improvement measures are put forward to the front structure of the bus based on the best energy absorption.The body deformation and the internal energy increment are compared with the best energy absorption requirements and the best improvement scheme is selected,the optimized acceleration curve and the original curve are compared in the curve characteristics,curve parameters and the results of occupant injury values to verify the effectiveness of the optimal curve.The results show that among these five improvement measures,increasing the thickness of the longitudinal beam can effectively improve the volume of the body and absorb more energy,thus reducing the impact force of the collision on the body and reducing the risk of occupant injury.The number of energy absorption can be determined by the accelerationdisplacement curve which can guide the design of frontal body structure of bus.The research in this paper can provide the basis and help for the improvement of body structure of bus in the design stage with reference to the acceleration curve of crash.