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It is well known that inappropriate dimensional tolerances can lead to diminished performance of an engine. This paper presents a method to determine the probabilistic dynamic errors of a single cylinder engine. The uncertainties considered in the analysis are tolerance on the link length, radial clearance and random pin center location. Such uncertainties create mechanical errors in the position, velocity and acceleration of the piston and crank and thus, influence the engine's performance. This research statistically determines the effect of tolerances on the global dynamic behavior of an engine. This study uses the effective link length model and adopts the Monte Carlo simulation method to determine mechanical errors in terms of standard deviations.

Humans are most sensitive to low frequency whole body vibrations often associated with roadways. As a result, improvement of vibration characteristics is an important aspect of vehicle design. While much research has been performed on active suspensions and their role in ride quality, comparatively little has been performed on seat dynamics. This paper develops a method of selecting optimal seat dynamic seat parameters with respect to ride quality. A nine degree of freedom dynamic vehicle simulation model is presented. An optimization procedure, using absorbed power as the objective function, then minimizes rider discomfort by manipulating the seat dynamic parameters. A two degree of freedom seat model yields four design variables, including seat suspension stiffness and damping and seat cushion stiffness and damping. The optimization problem is solved for several road inputs and two different vehicle models.

In order to develop an accurate and realistic accelerated life test, vehicle axle acceleration must be correlated to actual road profiles. This paper describes analytical and empirical methods used to correlate vehicle acceleration to road roughness. A quarter-car model was developed to simulate the vertical response of a vehicle. The quarter-car model uses a tire footprint to average the road profile. Pennsylvania Transportation Institute's (PTI) inertial profilometer was used to record road profiles of city streets through out Pennsylvania. Peak axle accelerations from actual accelerometer data were correlated with the profile's International Roughness Index (IRI). Additional road profiles were input to the quarter-car simulation model. The resulting accelerations from the simulation model fit the above correlation constructed with experimental data. Thus, a quarter-car simulation model can be used with road profile data to develop accelerated life tests.

Due to the special requirements of the transit bus operator's function, the environment can be a very difficult place to work, especially for large males and small females. This paper addresses the design of bus operator work stations to accommodate people from the 5th percentile female to the 95th percentile male. Results from a bus operator survey, task analysis and an evaluation of a proposed bus operator work station are presented. While attempting to maintain the amount of adjustment to a minimum, adjustment greater than present practice was included in components like the instrument panels, seat and steering column. The controls were grouped in the instrument panels by their function. Controls dealing with passenger pick-up and delivery are located in a right-hand instrument panel. A jury of over one hundred subjects evaluated the proposed work station. The jury evaluation showed that the work station will accommodate the above population extremes.