Study On Coach Body Structure Deformation And Occupant Safety Suffered To Explosive Impact

In recent years,terrorist activities are rampant,terrorist attacks also have become a threat to national security and social stability and people's happiness life,the research data show that the annual terrorist attacks accounted for more than 50%of all terrorist incidents^[1].As is known,the capacity of coach is several times larger than car's,and its speed is more slowly in relatively.While attacked by a bomb,the bus's damages will be much more serious,along with more casualties.From past to present,the domestic and foreign scholars and research institutions mainly focused on the explosion impact to military vehicles.Therefore,to carry out the research on the protection of buses during explosion impact is of great significance.Firstly,this thesis analyzed the advantages and disadvantages of numerical simulation methods of explosion simulation used by scholars,Arbitrary Lagrange Euler?ALE?method Conventional Weapon?CONWEP?method were selected to compare the deformation of the shell structure.Then the CONWEP method was selected as the blasting simulation method to the side of bus.Next this thesis elaborated the steps of using HyperMesh to modeling the finite element model of a passenger vehicle,then calculated the K file by the software of Ls-Dyna and analyzed the result of the stress distribution and deformation of the vehicle body by the softwares,Ls-Prepost and HyperView.And then the thesis analyzed the head injury and the thoracic injury in different positions in the bus.Finally,this thesis discussed the methods to improve the bus body structure about explosion-proof.And the foam materials were filled between the skeletons of the coach body to form a sandwich structure to improve the explosion attract was studyed,and then it studied how does the body's cover of different thickness and different materials influenced on the occupant's safety.At last,according to the similarity law of cubic root ratio established by Hopkinson,the influence of explosion shock wave on the safety of occupants in different fixed distance(Z=R/W^1/3)was studied.The simulation result showed that the invasion and deformation of the bus body structure were reduced more than 6.84%and 7.83%respectively under the same situation.The result also showed that this method could reduce the damage to the head and the chest.It's concluded that the damage to the head and chest was decreasing with the increase of the thickness of the body's cover,but for the shock wave from a long distance,the cover's thickness caused less head injury.The result also showed that the impact from the shock wave on the head injury came about mainly when the fixed distance was less than 3,while the impact on the chest injury mainly appeared in the time that the fixed distance was less than 2.When the fixed distance was larger than 3,it has a smaller impact on the safety of the passengers.This thesis analyzed the deformation characteristics of the coach's body and the occupant safety under lateral explosion shock loading by simulation,and put forward some structural improvement measures,which has important reference significance for improving the explosion proof performance of buses.