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A multi-body dynamics model of the U.S. Army3s High Mobility Multi-purpose Wheeled Vehicle (HMMWV) has been created using commercial software (ADAMS) to simulate and analyze the vehicle3s rollover behavior. However, manual operation of such simulation and analysis for design purposes is prohibitively expensive and time consuming, limiting the engineers3 ability to utilize the model fully and extract from it useful design information in a timely, cost-effective manner. To address this challenge, a commercial system integration and optimization software (OPTIMUS) is utilized in order to automate the simulation processes and to enable the more complex uncertainty-based analysis of the HMMWV rollover behavior under a variety of external conditions. Challenges involved in integrating the software are highlighted and remedies are discussed. Rollover analysis results from using the integrated model and automated simulation are also presented.

Warmup of the Du Pont model V reactor during unchoked engine operation with air injection has been characterized by a nonreactive period, followed by a transition to an ignited condition. The early period is quenched by heat loss. The transition is gradual for hydrocarbons, but more abrupt for carbon monoxide. Model building for the warmup period is directed to the objective of developing a rapid computer simulation to predict light-off times and temperature histories for various reactor designs and operating conditions. Reactor gas temperature and chemical conversions are calculated as solutions for an ideal backmix reactor. Heat balances maintain a record of all reactor metal temperatures for the given configuration. Heat transfer by radiation, convection, and conduction is considered. The presence of a hot spot in the reactor has a strong effect on time to light-off. In addition to lowering the time, such an ignition source shows a great sensitivity to combustible concentration.

This paper describes the friction characteristics of a 1.8 Litre J-car piston and ring assembly as influenced by oil rings of conventional design, but of varying tensions. In addition, the piston-ring assembly friction characteristics are reported for a set of oil viscosities ranging from 2 to 20 cSt with and without a molybdenum friction modifier. Multigrade oil results are shown also. Finally comparisons are presented between changes in friction measured by the Instantaneous IMEP Method and those measured by the dynamometer for the engine as a whole. Our results show large differences in piston-ring assembly friction as oil ring tension was varied. However, these differences became moderate after the oil ring broke-in. Both high and low oil viscosities increased piston and ring assembly friction. The friction modifier was most effective with a mid-range viscosity and provided virtually no benefit at viscosity extremes.