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This paper presents an optimization method of damping material attached on vehicle body panels incorporated with trimmed body calculation up to 400 Hz. Damping sheets are modeled by using shell elements whose neutral plane are located away from the middle plane of the elements. In this method the offset value must agree with the average of the thicknesses of a panel and a damping sheet attached on it. Therefore, we implement the function that can automatically change the offset values according to the change of the thicknesses of damping sheets during the iterative calculations of optimization. Interior sound pressure levels are employed as the constraint conditions by utilizing the precise acoustic cavity models that have been recently developed. The developed optimization technique is applied to reduce the weight of the damping sheets on the floor panels of a sedan car.

During the acceleration of a vehicle, the contribution of the exhaust noise to the interior sound pressure level is significant. The acoustic insulation brought by the trim components must be designed with that consideration in mind. As such, there is an increasing need for developing reliable methods for predicting the airborne noise transmission between the exhaust system and the sound pressure level at the passenger's ears, taking into account the positive impact of various trim components. This paper presents a methodology that has been developed for addressing this need. Based on a finite/infinite element method, the computational procedure is divided in two steps: 1 The first step involves the exterior acoustic field all around the vehicle.

This paper proposes a new hierarchical optimization technique for the vehicle body structure, by combining topology optimization and shape optimization based on the traction method. With the proposed approach, topology optimization is first performed on the overall allowable design domain in 3D. The surface is extracted from the optimization result and converted to a thin shell structure. Shape optimization based on the traction method is then applied to obtain an overall optimal body shape. In the shape optimization process, iterative calculations are performed in the course of consolidating parts by deleting those whose contribution is small. The result obtained by applying this method to the front frame structure of a vehicle is explained. The resultant optimal shape has stiffness greater than or equal to the original structure and is 35% lighter. This confirms the validity of the proposed technique. It was found, however, that some issues remain to be addressed.

This paper investigates the potential of using FEA poro-elastic Biot elements for the modeling carpet-like trim systems in a simplified setup. A comparison between FEA computations and experiments is presented for two layer (mass-spring) trim systems placed on a test-rig consisting in a 510×354×1.6 mm flat steel plate clamped in a stiff frame excited at its base. Results are presented for a given heavy layer with two different poro-elastic materials: one foam and one fibrous material. The investigations included accelerometer measurements on the steel plate, laser-doppler vibrometer scans of the heavy layer surface, sound pressure measurements in free field at a distance of 1 meter above the plate, as well as sound pressure in a closed rectangular concrete-walled cavity (0.5×0.6×0.7 m) put on top of the test-rig. Computations were carried out using a commercial FEA software implementing the Biot theory for poro-elastic media.

It has been reported that negative pressure value was detected on the sliding surface of paper-based porous frictional material which is used in the automatic transmission. In this study, the effects of sliding velocity, contact pressure and surface geometry including diameter of measurement hole, surface roughness of frictional material, and porosity on the pressure detected by the hydraulic system were investigated, and mechanism of the negative pressure generation was discussed. It is considered that the pressures produced by various origins are summated into the resultant value indicating negative in the conventional oil film pressure measurement system.

Recently, a requirement to fuel economy improvement is rising from the strong fear against the environment aggravation caused by CO2 that is discharged in the atmosphere. In such a situation, to pursue fuel economy, it pays attention to CVT and AMT as transmission form. However, the advantages and disadvantages about both of the transmission form weren't compared on the same condition in the past. In this paper, the shift schedule, the drive power characteristic, the body variation and the engine variation are kept the same conditions to examine both type of transmission. And evidence the potential of fuel economy improvement of CVT and AMT. In the case of CVT vehicles, increasing the ratio range was effective in increasing fuel economy when driving at relatively high speeds without much stopping and starting, while reducing friction was effective when driving at relatively low speeds with repeated stop and goes.

In Japan, Multipurpose vehicles (MPVs) are growing in popularity while sedan popularity is falling. Four wheel drive (4WD) systems on MPVs require wide range torque distribution because the vertical load distribution on the front and rear tires changes greatly. In order to satisfy this requirement for 4WD , Toyota Motor Corporation and Toyoda Machine Works LTD. have developed a new electronically controlled 4WD system named “Active Torque Control 4WD”. This system, by optimum driving force distribution, provides both good handling characteristics and low fuel consumption. And it enables compact drive-line size and light weight. This paper describes the development aims of the new system, its construction, its control and technological features.

It is said that the disc brake squeal is the noise caused by the friction-induced vibration between pads and rotor, by which the brake assembly resonates. In this paper, the forces on the pads and the accelerations of the brake were measured, and their results were discussed by the correlation of them. As a result, the forces acting on the pad were observed to vibrate at low cycle synchronizing with the revolution of rotor. And the friction coefficient curve indicates several parts of negative gradient and periodicity. This phenomenon was well correlated with the mechanism of the excitation of brake squeal vibration by the simulation result.

Influences of oil-flow and oil temperature on frictional torques of whole engine and main lubricating components were determined by motoring method. Oil-flow rate, temperature and pressure in main lubricating pathes were directly measured under the same conditions. Oil-flow rate and frictional coefficient of crankshaft system were estimated by theoretically analysing Reynolds’ equation. Experimental data were discussed based on oil-flow analyses in lubricating system. Engine frictional torque becomes smallest when the engine is supplied with an optimum oil-flow rate, 2.5 - 3.5 1/min where the ratio of oil-flow rate is 10 - 20 % in crankshaft system, 30 - 40 % in a piston-connecting rod system, and 50 - 60 % in valve system. The optimum oil-flow rate which minimises the frictional torque is 1 - 2 1/min for crankshaft and piston-connecting rod systems, and 3-4. 1/min for a valve system.