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In case of all-terrain vehicles (ATVs), which have characteristics of both motorcycles and cars, the effect of the rider movement can not be ignored when analyzing ATVs' behavior. We have developed a simulation system of an ATV with rider operations, which are throttle control and rider movement, by using multibody dynamic simulation software. To quantify the rider operations and verify the validity of the simulation system, we have conducted experiments and simulations on a sport-ATV in two jumping patterns. In this paper the results of comparison between simulation and experiment are reviewed. Then, we report the analysis results of the effects of the rider operations and the ground profile to ATV jumping behavior with using the simulation system.

A finite element model for an entire frame-structured sports utility vehicle was made to evaluate the characteristics of the idling vibrations for the vehicle. The engine exciting forces were determined by Souma's method to simulate the idling vibrations. The modeling of the power plant and the entire vehicle was verified by the reasonable agreement of the experiment and calculation results. Attention was focused on the frequency of the first-order vertical bending mode for the frame. It has become clear that the idling vibration level of the vehicle is lowered by decreasing the frequency of the first-order frame bending mode.

It is necessary to predict motorcycle performance at an early stage of development to minimize the period for designing, experimenting, and tuning. In order to do that, we have developed a motorcycle model with a mechanical dynamic simulation program. This model includes the bodies of a motorcycle, aerodynamic forces, tire forces, engine characteristics, simplified gear trains and driving chains, and rider operations. With this program, we have conducted motion simulation on steady state turn and disturbance response tests with two kinds of tire stiffness. We have also conducted experiment on the steady state turn and disturbance response tests to validate the program. In this paper, we analyze the results of the simulation and experiment. As a result, it is confirmed that the simulation results accord with the experimental results, and we have found that the steer angle and bank angle at the steady state turn depend on tire stiffness.

In recent years, Nearfield Acoustical Holography (NAH) has been used to identify stationary vehicle exterior noise sources. However that application has usually been limited to individual components. Since powertrain noise sources are hidden within the engine compartment, it is difficult to use NAH to identify those sources and the associated partial field that combine to create the complete exterior noise field of a motor vehicle. Integrated Nearfield Acoustical Holography (INAH) has been developed to address these concerns: it is described here. The procedure entails sensing the sources inside the engine compartment by using an array of reference microphones, and then calculating the associated partial radiation fields by using NAH. In the second part of this paper, the use of farfield arrays is considered. Several array techniques have previously been applied to identify noise sources on moving vehicles.

Since powertrain noise sources are usually “hidden” within the engine compartment, it is difficult to use NAH to identify those sources and the associated partial radiation fields that together create the exterior noise field of a motor vehicle. Integrated Nearfield Acoustical Holography (INAH) has been developed to address this concern. INAH represents a combination of NAH, reference microphone selection procedures, and coherence techniques. The procedure entails sensing the sources inside the engine compartment by using an array of reference microphones, and then calculating the associated partial radiation fields by using NAH. A key factor in the success of this procedure is the selection of a good reference microphone sub-set. A selection procedure has been developed by combining condition number and coherence analyses. The partial field determination problem has been approached by using both partial coherence and Singular Value Decomposition (SVD) procedures.

In 1990 AAMA and JAMA established the ILSAC/GF-1 Standard and API established its new SH Standard. The main feature of these new engine oil standards are lower viscosity and lower friction. AAMA and JAMA are preparing to establish the ILSAC/GF-2 Standard in 1997 and the ILSAC/GF-3 in 2000. Motorcycle engine oils have been produced on the basis of automobile oils with minor modification so as to ensure a worldwide availability of motorcycle oils. Motorcycle industries are concerned; that is, based on the new standards for automobile engine oils, do motorcycle oils truly conform with the required performance of motorcycles? According to this study, friction coefficient and viscosity must be considered to select motorcycle engine oils.