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The purpose of this study is to clarify how the residual stress determined by the configuration of weight reduction holes affects the crack initiation in the brake discs for large motorcycles under the over loading condition. Two kinds of test samples of the one-piece type brake disc were used where the configuration of the weight reduction holes were different. The test result showed that the crack initiation life was significantly changed due to the configuration of weight reduction holes. The 3D FEM results of heat transfer and thermal stress analysis explained that the stress relaxation was dependent on the configuration of weight reduction holes of the disc because the initial thermal stress was directly determined by the simple stress distribution around each hole. This study confirmed that the configuration of weight reduction holes plays a decisive role in determining the design of the brake disc.

Braking tests under overloading were carried out using large one-piece brake disks having eyebrow-shaped holes as decoration. When the number of braking cycles was more than five, permanent deflection of the disks was observed. When the number of braking cycles was less than six, no appreciable deflection occured. The experiment revealed that such deflection occurrs during the cooling process after the final braking cycle. The mechanism for this phenomenon is explained based on the deflection-time record in conjunction with the temperature distribution of disks and its variation with respect to time. The key for this phenomenon is yielding in tension at the bridges between holes. The deflection occurs due to elastic-plastic buckling caused by shrinkage of the flange. Numerical simulations were successfully conducted by using a general 3D FEM in consideration of geometrical and material non-linearities.

This study discussed the mechanism of the low speed judder for wave type brake disc developed newly for recent motorcycles. Wavy disc was examined to investigate the effect of wave configurations on the BTV (Brake Torque Variation) behavior. Torque amplitude in braking was compared with respect to the revolution order which represented the multiple number of the number of revolutions. To explain the mechanism at the mode showing largest BTV, the elastic deformation of the pad was analyzed by finite element method concerning geometrical nonlinearity with commercial code. This study found that most crucial BTV appeared on low speed judder was observed at the 3 rd peaks on the revolution order. Test data showed that this crucial BTV was related with the number of waves at the disc periphery, and caused by the indentation of the pad into notched part at disc periphery.

The purpose of this study is to propose an effective model to estimate the excitation force accompanied with stick-slip between shoe and disc, considering the strain distribution on contact surface of the shoe, and then to propose an effective concept to design the brake which reduced the brake squeal under practical use. In order to investigate the influence of configuration of the hole, three types of discs were prepared in which the size of holes was different. The SPL (Sound Pressure Level) and the frequency of squeal for three types of discs were measured when the brake squeal was observed at conditions of low sliding speed. The change of stability of the brake shoe passing on hole was analyzed by 2-D simplified brake system model.

The purpose of this study is to characterize the brake torque variation (BTV) of the developed brake system using wave type brake disc. The brake torque was fluctuated when the pad passed at the point of the wavy shape. The indentation of the pad into the space of wavy shape was observed. These results indicate that remarkable peak of the BTV of the wave type brake disc was related with the pad deformation. In the devised test, remarkable peak of the BTV of the wave type brake disc was decreased by insertion of spacers. This paper proposed an effective aspect to prevent the BTV of the wave type brake disc.

In order to reveal the mechanism of noise generation from CVT (Continuously Variable Transmissions) using a dry hybrid V-belt, the power spectrum of sound from a two-pulley CVT system and its variation with respect to rotational speed were measured. The experimental results showed that the frequency of the first peak in the power spectrum of the observed sound linearly increased with increasing the rotational speed of the pulley. The sound frequency of the first peak coincides with the frequency derived from the belt block pitch and the belt speed. Then, sound intensity analyses were conducted to identify noise sources of CVT. The experimental results reveal that unpleasant sound whose frequency is high occurs due to the collision or slip between CVT blocks and the pulley groove at the entrance and the exit of V-groove pulleys. Pulley surface roughness strongly affects the noise level. Additionally, the location of noise source varies due to surface roughness of the pulley groove.

A new three-pulley CVT (Continuously Variable Transmission) with a tensioner has been developed using dry hybrid V-belts. It can transmit higher torque than conventional two-pulley CVT without a tensioner, because the tensioner increases not only a lap angle where power is transmitting but also it can always keep the belt tension optimum. This study shows whether the Euler's power transmitting theory is applicable to the tensioner type CVT to characterize the CVT operation for preliminary design. The tensioner type CVT has also high shifting speed and it does not need large thrusts on both driving and driven pulleys during shifting since the minimum tension for torque transfer is assured in the slack-side string. The FEM analysis revealed the shifting mechanism and showed that the transmitting force distribution in the pulley groove for the newly developed CVT is almost the same as that for the conventional CVT.

Two-layered clutch plates manufactured by a new process using BMC show a significant deflection. Two methods solving such deflection were alternatively developed in this study. Changing the composition of the clutch plate appeared to be useless while after-curing on deflected clutch plates was effective. Thermal cycles or high pressure for after-cure did not reduce the deflection. However, applying after-cure with a sloped mold reduce the deflection without increasing the disk density.

Brake discs have some holes in the flange for promoting heat dissipation as well as refreshing the pad surfaces. One-piece brake discs are desirable even for large sizes in order to reduce the production cost. However, cracks exceptionally occurred from some holes in the flange during braking under extremely severe test conditions for one-piece brake discs. On the other hand, no cracks were observed under the same condition for two-piece brake discs consisting of a hub and a flange. The objective of the present work is to show way cracks occur in the case of one-piece brake discs. Cyclic braking tests under extremely severe conditions were carried out using large one-piece brake discs having some hole in their flange. When the number of braking cycles was beyond 300, some tiny cracks occurring around holes were found. They grew in the radial direction of the brake discs.

In Metal V-belt type CVT, an elastic deformation of blocks determines the shifting speed and the pulley thrusts at transitional state. Both driving and driven pulley thrusts were calculated by considering the forces acting on blocks at a pulley entrance, which agreed with the experimental results at not only steady state but also transitional state. The frictional performance of CVT fluids and the frictional characteristics between blocks and a pulley were evaluated by applying the mean coefficient of friction as a friction parameter. It was found from the experiments that the estimated coefficient of friction of CVT fluids was not constant with respect to operating conditions. It changed due to relative sliding speed between blocks and the pulley, sliding direction and normal pressure acting on V-surface of the block.

Tiny (hair-like) cracks initiated around small holes in the flange of one-piece brake discs were observed at an overloading condition. Thermally induced cyclic stress strongly affects the crack initiation in the brake discs. In order to show the crack initiation mechanism, the temperature distribution at the flange was firstly measured. The temperature distribution under overloading was analyzed by using the finite element method. Based on the experimental and calculated results, the crack initiation mechanism for one-piece brake discs at the very severe braking condition was explained. In addition, the effective methods are suggested for reducing the initiation of tiny cracks around the holes.

The aim of these experiments is to determine the best way to obtain high mechanical properties for phenol resin and glass fibers based composites. Various ways of fabricating the material were studied, as well as its best composition. The conditions of drying, molding processes were optimized. From the most conventional method, using ethanol as a solvent to newer ones, including continuous ways of processing and the use of water instead of ethanol, a lot of possibilities exist to produce such a material. This paper explains the advantages and drawbacks of a whole range of manufacturing processes.

An advanced numerical model is proposed to analyze the power transmitting mechanisms of a CVT using a metal V-belt. By using the present model, forces acting on the belt are well estimated not only at steady states but also during transitional states where the speed ratio is changing. The numerical results show that blocks are in compression in both strands when the speed ratio is rapidly shifted. A complementary model is also developed to analyze the load distribution among bands which form the ring. The load distribution in the ring is governed by the difference in coefficients of friction among elements.

The purpose of this paper is to analyze the force distribution between pulleys and blocks of a newly developed CVT belt. Three components of the force (transmitting force, normal force and frictional force) were measured directly using a newly devised pulley. The experimental results reveal that the transmitting force distribution on the driving pulley is similar to that on the driven pulley as long as blocks do not slip while the distribution of the normal force component for both pulleys does not resemble each other as well as the distribution of friction force in the radial direction of the pulley. It is also found that no idle arc exists in the contact arc of both driven and driving pulleys even in the case that the transmitting torque is low. The experimental force distribution is compared with a theory based on the discrete spring model taking no consideration of slippage between the pulley and the blocks.

A concept and a (nonlinear finite element) model of how to analyze load distribution of toothed belts having curvilinear tooth profiles for automotive engines at steady states was developed by utilizing a general nonlinear finite element program considering contact problems as well as geometrical nonlinear problems. A toothed belt in the model consists of circularly linked beam elements for endless tension members and two dimensional solid elements for a belt body. A curved pulley surface is supposed to be rigid. Interaction between surfaces of belt teeth and pulleys is considered as moving boundaries. A quite good agreement between experimental and computed results for frictional forces and tooth load confirms that the proposed model is presently the only one practical approach for analyzing load distribution of toothed belts which none of the existing theories can do. Some numerical simulations were performed by changing parameters such as belt pitch, dimensions of teeth and so on.

It is very important to know the load distribution in pulleys to predict the life of toothed belts. In this study, a simple model consists of springs and friction elements has been developed for numerical analysis of the load distribution. A sample problem with steady pulley motion for a two pulley system was analyzed. The analytical result was compared with the experimental result. It was also compared with the numerical result by the alternative model using FEM. Relatively good agreements between them were obtained. A typical problem for the two pulley system subjected to fluctuating torque loadings was also analyzed by the present model. The calculated result shows a large difference in tooth load distribution between the steady state case and the unsteady state one.

The effects of CNBR (cross-linked acrylonitrile butadiene rubber) modification on the fracture characteristics of epoxy adhesives were investigated under Mode I static loading. Fracture tests were conducted by using DCB (double cantilever beam) specimens. Rubber content, adhesive thickness and loading rate were changed. The crack extension resistance (given by energy release rate) of the epoxy adhesives was much improved by CNBR modification. For the rubber modified epoxy adhesives, the crack extension resistance becomes high with an increase in adhesive thickness as well as loading rate. The reason why the CNBR modification improves the crack extension resistance was explained based on the surface observation and fractal dimension of the fractured surface.

The effects of inclusion of glass beads and rubber modification on the fatigue fracture characteristics of an epoxy adhesive were investigated. Hybrid effects were also investigated when not only the epoxy adhesive was rubber modified but also when glass beads were mixed simultaneously. Fatigue crack growth resistance was greatly increased due to glass beads, CTBN and CNBR modifications at the second stage of crack growth (da/dN=10-4-10-3 mm/cycle). However, the energy release rate at threshold for both CNBR and CTBN modified adhesives were lower than that for the unmodified adhesive. No significant hybrid effects were distinguishable.

A new parameter was proposed to evaluate the fatigue life of toothed belts. The parameter is the frictional work spent on the belt tooth surface for driving and driven pulleys. It can be estimated only with the 2D finite element model of the belts previously developed by the authors. As well as the frictional work, an alternative parameter, maximum tooth load (widely used in the literature) was also used to evaluate the fatigue life of toothed belts. In order to prove the effectiveness of the present parameter, fatigue tests were conducted using S8M belts at a constant power. The test results show that the maximum tooth load can explain the fatigue degradation of the toothed belts to some extent while the proposed parameter, the frictional work can evaluate the fatigue life of the belt due to wear of the belt facing fabric more appropriately than the maximum tooth load.

Some theories on the behaviour of CVT using metal pushing V-belts have been recently drawn. However, our previous experiments did not well prove their prediction. A numerical model which can calculate all block motions of the belt was developed in this paper. Using this model, some steady states of power transmitting of CVT were calculated and compared with the previous experimental results. Satisfactory agreements were obtained between two results in all ratio. This model is effective to estimate the CVT response at steady states.