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Strengthening bus frames to maintain residual space occupant space an and minimizing occupant injury are necessary. As a firstt step, st before we go for complete rollover simulation, the critical cal bus body joints are physically tested same is repeated by simulation approproach once we have the correlating results approval is taken n from f ARAI. As a second step, the complete vehicle rolls over simulation was wa performed.
An average Element edge length gth of 10 mm is maintained in the critical regions and 30mm m in the noncritical regions.
The engine, power transmission, suspension and an axles were modeled by 1D element. Mass balancing was as done using balancing tool in HyperCrash V11 Unit system followed: KN, mm, ms, kg Introduction Buses are generally believed to be very safe. A study by Pearce et al. Also, a rollover can cause up to five rotatio tions to occur on the road. Lastly, a comombined rollover involves two different dangers; for example,le, a head-on collision that leads to a rollover, orr a rollover that ends with the bus in a lake.
The most typic ical collision configurations involving buses and d coaches are side, rear, frontal and rollover. Although rollov lover crashes are not common, the number of seri eriously injured occupants was high as compared to other cr crash types , however, the research and intere erest related on its safety seemed relatively low.
In most parts of the world, especia cially in Europe, safety requirements are continuo nuously visited to improve passenger safety in buses or coa oaches. Since there are many seriously wounde ded passengers in traffic accidents of buses, more careful an analysis and simulation for impact accidents should uld be investigated. Albertsson et al. They investigated on victims with re regard to injury outcomes, mechanisms, and poss ossible injury reduction for occupants when using a safety belelt.
In fact, Matolcsy ] collected c the statistics of over rollover accidents, which ch showed the average casualty rate to be 25 pe per accident. In case of a rollover, the passengers run the risk ris for being exposed to ejection, partial ejection, n, projection, or intrusion, and are thus exposed to a high fatality fa risk [6, 7]. However, the most dangerouss one is intrusion. Due to Simulation Driven Innovation 1 large-scale structural deformations ns, structural parts intrude into the passenger orr compress them lack of strength of the superstructure .
During a bus or coach rollover, th the occupant will have a larger distance from the th center of rotation as compared to that of a car occupan ant. For this reason, the Automotive Indian standa dard, Regulation No. This means, the vehicle including g all its structural parts, members and panels and all projec jecting rigid parts such as luggage racks, on-the roo roof ventilation equipment, should not intrude inside the Res esidual space.
However, bulkheads, partitions,, rrings or other members reinforcing the superstructure of the vehicle and fixed appliances such as bars, kitchenettes kitc or toilets shall be ignored. The cross sectio ction of the residual space, perpendicular to the length is a trap apezoid and it runs through the length. Figure 1: Residual space Process Methodology Below option was selected for appro proval and agreed with test agency. Simulatio ation results will be supported by physical determin mination of C.
G of the bus and testing of critical bus body joints ints and subsequent approval. Simulation Driven Innovation 2 Geometric Model All geometrical details were obtaine ined from reference drawings. The midmid-surfaces of these CAD model were extracted, d, since most geometrical features of the bus have been defin fined with thickness, to proceed for shell-meshing. Most components of the structure were ERW steel tubes off square, s rectangular and hat cross-sections Fig Masses were imposed according to a structured methodo dology.
Firstly, a list of vehicle masses was prepa pared. The engine, power transmission and suspension were ere modeled by 1D element. The axles were modeled mo using rigid truss elements and the mass and inertia tia are imposed using the same method.
The fixed ed masses were imposed by using mass elements. The dist istributed masses were imposed by changing the density of the related region. FE model of the full vehicle was com comprised of first order shell elements, 73 spring elements and 44 mass elements ADMAS and 48 Rigid Elements. An average Element length of10 o mm is maintained in the critical regions and for the regio gions under the floor lower structure-chassis elemement length up to 30 mm was used.
The roof structure is mes eshed with 10mm fine mesh to accurately capture re deformation. For all the super structure parts, QEPH formu mulation with 5 point integration was assigned.. FRPRP and glass are included in the model which is an important nt component for structural integrity. Finally after the th FE model generation, mass balancing was done to bring g the t global COG as close as possible to the physi ysically calculated COG. Residual space is connected to the he high stiffness region on the axle which does notot affect a the structural strength in any manner.
The axle is rigid and mass is added at appropriate locations ns. Ditch is modeled as fixed ed rigid wall. A graph showing the various energy distribu ibutions from the rollover simulation of bus structure Fig.
The T figure shows that energy distribution did rememain constant, indicating that analysis results were accurate te. Grant, A literature analysis with special focus on injury inj causation and injury mechanisms, Accident Analysis and Prevention 37, — Strength of the superstru tructure of large passenger vehicles. Regulation Revision 1. Simulation Driven Innovation 7 Related Papers.
United Nations Economic Commission for Europe
Rollover accidents are a major concern for passenger safety in buses. Considering social and economical impact, AIS regulation is being implemented in India from October , which is equivalent to ECE-R66, specifying requirement of strength of superstructure of buses during rollover. The AIS standard specifies four different methods viz. Each method has its own advantages and disadvantages. Application of the standard also needs engineering evaluation of various aspects such as determination of a vehicle family and worst case among that family, which side to rollover, etc.
New Mod SR2 ECE.R66
Approval No. Extension No. Trade name or mark of the vehicle type Vehicle type Brief summary of description of the superstructure in respect of paragraph 3.
Seguridad en caso de accidente
Length shall not be greater than two-thirds of the distance between the surface on which the vehicle stands before it is tilted and part of the rim of the wheel which is nearest to the surface 20 mm 10 mm mm minimum; 1. The wheel supports at the widest axle shall be placed on the tilting platform so that the side of the tyre is at maximum mm from the axis of rotation; 1. The wheel supports at the other axles shall be adjusted so that the vertical longitudinal centre plane VLCP of the vehicle shall be parallel to the axis of rotation. The tilting platform shall be constructed to prevent the vehicle moving along its longitudinal axis. The impact area of the ditch shall have a horizontal, uniform, dry and smooth concrete surface. The vehicle to be tested need not be in a fully finished, "ready for operation" condition.