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The tire is one of the most important parts, which influence the noise, vibration, and harshness of the passenger cars. It is well known that effect of rotation influences tire vibration characteristics, and earlier studies presented formulas of tire vibration behavior. However, there are no studies of tire vibration including lateral vibration on effect of rotation. In this paper, we present new formulas of tire vibration on effect of rotation using a three-dimensional flexible ring model. The model consists of the cylindrical ring represents the tread and the springs represent the sidewall stiffness. The equation of motion of lateral, longitudinal, and radial vibration on the tread are derived based on the assumption of inextensional deformation. Many of the associated numerical parameters are identified from experimental tests.

This paper describes a steady vibration of an engine supported by rubber and hydraulic mounts at a relatively low frequency range, assuming an engine is a rigid body. We identify dynamic characteristics of a hydraulic mount with respect to frequency and amplitude. The equation of motion is solved numerically by the Newton-Raphson method, treating the mount characteristics as functions of frequency and amplitude. The excitation test to simulate an engine shake and an idling vibration was performed using a mass block instead of an actual engine. During the engine shake, we observed that the amplitude dependency of hydraulic mounts strongly influences the vibration, while idling, we investigated rolling vibration especially for the case where the torque axis does not pass through the engine's center of gravity. The theoretical predictions agree closely with the experimental results in both engine shake and idling vibration tests.

In order to reduce CO₂, Electric Vehicles (EV) and Hybrid Vehicles (HV) are effective. Those types of vehicles have powertrains from conventional vehicles. Those new powertrains drastically improve their efficiency from conventional vehicles keeping the same or superior power performance. On the other hand, those vehicles have an issue for thermal energy shortage during warming up process. The thermal energy is very large, and seriously affects the fuel economy for HV and the mileage for EV. In this paper, we propose VHDL-AMS multi-domain simulation technique for the estimation of the vehicle performance at the concept planning stage. The VHDL-AMS is IEEE and IEC standardized language, which supports not only multi-domain (physics) but also encryption. The common modeling language and encryption standard is indispensable for full-vehicle simulation.

To reduce tire/road noise, it is important to examine the noise generation mechanism. Noise generated by a rolling tire is mainly emitted from the tread block. However, it has recently been reported that smooth tires also generate noise recently. This paper remarks on a smooth tire vibration by rolling on the road. The vibration of a rolling smooth tire is mainly vibration excited from the road surface. It is difficult to measure the input from the road surface, so we measured the tire's vibration at the leading and trailing edges. Scan Laser Doppler Vibrometers were employed to measure the vibration of the tire tread.

Recently, the development stage of agricultural vehicles such as the tractor has focused on new demands to improve the cabin environment. Especially the ride comfort has become increasingly important. For this purpose, rubber bushes have been installed the tractor to reduce road vibration to the driver in the cabin. However, this device does not sufficiently suppress vibration. This paper presents a method of vibration reduction that installs a semi-active suspension in the lateral and vertical directions at the cabin mount position of the tractor. In numerical simulation, the tractor model installed with a semi-active suspension is superior in performance to the conventional tractor model.

Improvement of vehicle interior noise is desired in recent years in the modern world of the demand of low weight, good fuel economy and offering technical advantages strongly. The dynamic force transmission of rolling tires from the road surface to the spindles is a critical factor in vehicle interior noise. We focus on structure-borne noise transferred through the spindle. It is necessary for effort of the effective tire/road noise reduction to predict spindle force excited by tire/road contact. The major issues in predicting spindle forces are to clarify the distribution of road forces and how to input on the simulation model. Therefore, it is important that road forces are measured accurately on the rolling tire. First, the dynamic road forces on the rolling tire are measured by using the tri-axial force sensor directly. In efforts to reduce interior noise due to structure-borne noise, it is necessary to predict spindle forces excited by the tire/road contact.

A new discrete model was developed in order to analyze the power transmitting mechanisms of a dry hybrid V-belt CVT not only at steady states but also at transitional states where the speed ratio was changing. Block tilting in the pulley was considered in the advanced numerical model as well as pulley deformation due to pulley thrust. The validity of the present model was well confirmed by comparing the calculated results on transmitting and normal forces with the former experimental results. The calculated results showed that both block tilting and pulley deformation meaningfully affected the pulley thrust ratio between the driving and the driven pulleys.

This paper presents an analytical model for the prediction of piston secondary motion and the vibration due to piston slap. For the modeling of piston slap phenomenon, cylinder liner is modeled as a several spring-mass system that are connected by modal characteristics, and lubricant film between the piston and the cylinder is modeled as reaction force vectors which excite resonant mode of them. By comparing experimental results and analytical ones, the validity of the proposed model has been confirmed. The optimization of the piston skirt profile is also carried out with the analytical model, and it is confirmed that the round shape of the lower part of piston skirt is effective for the reduction of piston slap excitation.

Current simulation of Noise, Vibration and Harshness (NVH) using Computer Aided Engineering (CAE) often uses a large DOF and detailed finite element model along with improvement of CAE technology and computational performance. By using a detailed model, predictions of precise vibration characteristics become possible. However, the number of eigenmodes in the target frequency range increases and engineers require a lot of time to examine eigenmodes and establish countermeasures. In this paper, a practical method of efficient and effective analysis by classifying target eigenmodes into a small number of groups is proposed. The classification is executed based on the relation between the dynamic characteristics of the entire automotive body structure and substructures.

Dual mass flywheel (DMF) is a well-known isolation system for vehicle drivetrain. DMF has two typical elastic energy storage systems: long travel arc springs and in-series spring units (including two or more springs) and sliding shoes connected in series. DMF has such complex nonlinear characteristics as torque-dependent torsional stiffness and rotational speed-dependent hysteresis friction due to its dependency of centrifugal force that is applied to components and radial force of springs. Because of this complexity, sub-harmonic vibration (SHV) may occur under certain circumstances, such as under light-load and high-rotational conditions. In general, since SHV’s frequency is 1/2 or 1/3 of the engine’s combustion frequency and may cause human discomfort, DMF must be designed robust against such nonlinear vibration. In this paper to reduce the SHV occurrence and to show a more robust design indicator, the SHV causing the mechanism is researched by testing and 1D CAE modeling.

This paper describes the identification of a sound source model for diesel engines installed on agricultural machines by using Inverse-Numerical Acoustic (INA) analysis, and noise predictions using the sound source model identified by INA. INA is a method of identifying surface vibrations from surrounding sound pressures. This method can be applied to sound sources with complicated shapes like those in engines. Although many studies on INA have been conducted, these past studies have focused on improvements to the identified accuracy and prediction of noise in free sound field or hemi-free sound field. The authors accurately predicted the sound pressure levels of engine enclosures using a sound source model identified by INA and a boundary element method (BEM). However, we had not yet verified the effectiveness of this sound source model against enclosures that had sound absorbing materials and openings.

This paper describes the relationship between the rider's evaluation of feeling of pulse and the seat vibration of the cruiser-type motorcycle. A simulated running condition was created to measure the seat vibration and engine speed. Next, the seat vibration was reproduced on the hydrodynamic shaker. Finally, we examined the influence of which order of rotational speed effects evaluation of feeling of pulse in a forced vibration test. As a result, it is known that 0.5th and 1st orders of seat vibration contribute to evaluation of feeling of pulse near 1,500 to 2,000 rpm of engine rotation.

The purpose of this paper is to establish a method of predicting the noise and vibration of tractor cabins in the engine-idling state by using Statistical Energy Analysis (SEA). At first, an analytical model of a tractor cabin is constructed, and power flow equations are formulated for the tractor cabin. To solve these equations, SEA parameters are estimated experimentally and analytically. These parameters are the modal density, loss factor, coupling loss factor, and input power. With these parameters, the noise and vibration responses of the tractor cabin are calculated. Good agreements are found between the analytical and experimental data.

In this study, the air suspension is newly applied to the engine mounting layout for getting the significant vibration isolation effect. In this case, the genetic algorithm so called GA is also applied for the optimization of many parameters, calculations of stiffness matrix and inverse stiffness matrix to prevent the coupled vibration of lateral and rolling modes and to obtain the displacement of each mounting point. As a result, inexperienced engineers can easily obtain the optimum engine mounting layout in a minute. By the confirmation test of FEM, the engine lateral vibration level at 25Hz dropped below 1/10 and its effect was significant.

The demand for quieter vehicle interiors increases year after year. The dynamic force transmission of rolling tires from the road surface to the spindles is a critical factor in vehicle interior noise. We investigated the dynamic force transmission of a rolling tire as it relates to reducing vehicle interior noise. A test with a tire rolling over a cleat was conducted in order to measure the road forces and the spindle forces. The transfer function of the rolling tire was identified from the experimental results by applying multi dimensional spectral analysis. In addition, Computer Aided Engineering (CAE) technology has advanced recently. This enables prediction of spindle forces early in the design stage. One of the most important issues in predicting spindle forces accurately is to clarify the distribution of road forces. This paper also describes the distribution of the dynamic road forces of the rolling tire.

This paper describes damping loss factor prediction in statistical energy analysis (SEA) for co-generation system (CGS) enclosures. To accurately predict vibration and noise by SEA, it is important to estimate parameters called the damping and coupling loss factors. In this study, the damping loss factors were estimated by the decay ratio method and a technique for calculating the modal damping ratio that uses a multi-degree of freedom curve fit. The calculated loss factor was applied to the vibration prediction of the co-generation system, and the influence of the internal loss factor calculation method on prediction accuracy was verified.

In this research, we aim at the construction of a steering cooperation-type front-wheel steering control system to reduce the rider's steering load by stabilizing the behavior of the motorcycle when turbulence in the direction of a roll occurs during low-speed driving. Finally, a front-wheel steering control system that considers cooperation with a rider's steering based on the experimental result is constructed, and the utility is verified by simulation.

This paper describes new method for selecting optimal field points in Inverse-Numerical Acoustic analysis (INA), and its application to construction of a sound source model for diesel engines. INA identifies the surface vibration of a sound source by using acoustic transfer functions and actual sound pressures measured at field points located near the sound source. When measuring sound pressures with INA, it is necessary to determine the field point arrangement. Increased field points leads to longer test and analysis time. Therefore, guidelines for selecting the field point arrangement are needed to conduct INA efficiently. The authors focused on the standard deviations of distance between sound source elements and field points and proposed a new guideline for optimal field point selection in our past study. In that study, we verified the effectiveness of this guideline using a simple plate model.

The objective of this study was to investigate the change of relative local velocity in each pulley groove at sliding between the belt and pulleys for a metal-pushing V-belt type CVT where micro elastic slips were inevitably accompanied to transmit power, while the transmissions were widely adopted to provide comfortable driving by continuously automatically adjusting the speed ratio. Local changes of wrapping radial position and velocity of the belt in each pulley groove of the CVT were simultaneously measured by a potentiometer with a spinning roller in the experiments. The mechanical power generated by the AC motor was transmitted through the CVT unit from the driving axis to the driven axis as usual under practical conditions while the speed ratio was set to 1.0. Pulley clamping force was applied by oil pressure.

Operator comfort is an important design criteria for hydraulic excavators during working and idling conditions. An engine, a cooling fan motor and a pump are installed on a hydraulic excavator. It is hard to identify the vibration contribution to a response because three sources are synchronizingly working. This paper describes the use of partial coherence measurement techniques for source identification. And it is examined to reduce the vibration of the source component identified by the partial coherence results. Finally, it is verified that the response acceleration is effectively decreased by reducing the vibration of the identified component.