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This paper presents a recently built school bus finite element (FE) model and several analyses performed with it. The model includes structural features typical for a school bus and is aimed to be capable of providing representative results of the school bus dynamic response in different crash scenarios. It has enough degree of detail to provide adequate accuracy and reliability of the results and at the same time be feasible to run on the presently available hardware. The school bus model has been tested using the commercial explicit FE code LS-DYNA to represent crash events involving other full-scale FE vehicle models used as bullet vehicles. Events of different duration are analyzed: from several hundred milliseconds of a vehicle-to-vehicle rear and side impact crashes to several seconds of a school bus rollover. The described work presents details of the bus model and discusses some important aspects of the vehicle modeling. Representative results and discussions are also provided.

A tractor-trailer combination unit was driven by remote control and overturned onto its driver's side during an overcorrecting maneuver at 40mph. The purpose of this tractor-trailer rollover test was to gain insight into the vehicle dynamics of a rollover and assess occupant protection during such an event. IMMI personnel first modeled the rollover using TruckSim software to predict the overturning maneuver path, required speed and location of ballast within the trailer. Simulation also enabled proper positioning of cameras and instrumentation to capture the event. Triaxial accelerometers and Dynamic Measurement Units (DMU's) recorded six degrees of freedom to characterize tractor and trailer vehicle dynamics. The driver and passenger seats in the tractor were equipped with the LifeGuard Technologies RollTek system, which includes a roll sensor, seat and seat belt pretensioning systems and side rollover airbags.

Federal Motor Carrier Safety Requirement (FMCSR) 393.76(h) states that “a motor vehicle manufactured on or after July 1, 1971 and equipped with a sleeper berth must be equipped with a means of preventing ejection of the occupant of the sleeper berth during deceleration of the vehicle.” [1] Furthermore, this standard requires that “the restraint system must be designed, installed and maintained to withstand a minimum total force of 6,000 pounds applied toward the front of the vehicle and parallel to the longitudinal axis of the vehicle.” [1] Today, sleeper berths are equipped with sleeper restraint systems that function to contain the sleeper occupant inside the sleeper berth during reasonably foreseeable crashes. To assess the effectiveness of sleeper restraint systems, computer simulation models of the sleeper cab environment and these restraint systems were developed, with a simulated supine occupant in the sleeper.

Building upon prior research, this paper compares computer simulations to a previously conducted rollover crash test of a tractor-semitrailer. The effects of torsional stiffness were elucidated during the correlation of simulations to the rollover test. A commercially available vehicle dynamics and reconstruction software was used for the simulation. Unique aspects of the rollover crash test were modeled in the simulation. A tractor-semitrailer quarter-turn rollover crash test conducted by IMMI was reconstructed using impact and vehicle dynamics models within the simulation software HVE (Human, Vehicle & Environment). The SIMON (SImulation MOdel Non-linear) module and the DyMESH (Dynamic MEchanical SHell) module within HVE were used. During the IMMI test, onboard instrumentation recorded acceleration and roll rate data in six degrees of freedom to characterize both tractor and semitrailer dynamics before and during the rollover event.