Study On Simulation Of A School Bus Rollover Crash And Structural Safety

In recent years, the casualty accidents caused by taking non-standard school busoccur frequently in all parts of the country, which seriously threatens the personal safetyof primary and medium-sized students and has caused wide public concern. Rolloveraccidents are a big part of school bus collision accidents, and the rollover accidents with“group death and group injury” bring about a great harm to the society. Therefore, it isnecessary to enhance the further study on the rollover safety of school bus bodystructure, in order to improve the rollover safety of the school bus, and protect thestudents’safety.This paper is mainly about the study of the finite element simulative methods onschool bus rollover crash and the rollover safety of school bus body structure. Taking aschool bus as the object of the study, the simplified finite element model of the schoolbus frame structure for analysis is established. Using HyperWorks/OptiStruct tosimulate common and modal working conditions of the model established above, thestrength, stiffness and dynamic characteristics of the school bus frame structure arechecked, to verify its reliability and effectiveness. A simplified method of rollover testsimulation based on the process of the law of energy conservation is adopted. Thesimulation calculation model of rollover crash of the school bus is calculated withLS-DYNA and the post outcome of it is got with HyperView and HyperGraph. With thesimulationresults, a further studyon the body structure’s deformation, characteristics ofenergy absorption, collision force and acceleration is carried out, and the results showthat the less strong insensitive structures are the side wall and the roof structures,leading to a large intrusion of the upper structures into the passenger living space andthe maximum intrusion of the fourth window pillar on the right side reaches to153.945mm. As far as the serious deformation of the weak parts of the school bus bodystructure is concerned, some improvement measures are taken, such as adding diagonalbracing structures between the side wall and roof structures, or embedding fortifiedrectangular steels in the weak parts. The results show that the improved body structurehas an evident effect and the rollover safety of it is improved for the passenger livingspace has not been intruded into. By comparing body structure’s deformation,characteristics of energy absorption, collision force and acceleration of two differentmodels, the frame structure either with or without body skin in the process of rollovercrash, it gets that it is the body skin that has a greater influence on rollover crash simulation results. Therefore, the body skin should be added to the frame structure inorder to make the simulation results more close to the actual test. The dynamicsimulative process of the school bus rolling crash is carried out by reference to themodified rolling test methods in the regulations of FMVSS208, then the bodystructure’s deformation, the change in energy and collision force of the rolling system inthe process of rolling crash are analyzed based on the result data, and the results showthat the large deformation of the superstructure seriously affects the passenger livingspace, and the schoolbus’ rolling safetyperformance needs to be improved.The study on the simulative technical methods and the process of school bus rolloversafety in this paper provides a certain reference value and practical significance for thebuses’superstructure safetyresearch.