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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.

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.

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.

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 temperature, crack tip opening rate and rubber content on static fracture characteristics of CNBR (Cross-linked acryloNitrile Butadiene Rubber) modified epoxy adhesives were investigated under mode I loading. Loading-unloading tests were statically performed by using DCB (Double Cantilever Beam) specimens. The fracture toughness increased with increasing the rubber content. The fracture toughness of CNBR modified and unmodified epoxy adhesives was much influenced by temperature and crack tip opening rate. The surface topology of fractured surface was changed by temperature and type of adhesive.

Six forces act on the block of a metal pushing V-belt. Previously, we successfully measured these forces at steady states using devised blocks and a telemeter system. In this paper, six forces are measured using the same testing and measuring systems at transitional states where a speed ratio varies from low to high, or vice versa. The experimental results reveal that distributions of four forces at transitional states except normal and frictional forces between rings and blocks are different in shape from those at steady states.

In this study, distributions of block compression force on the driving and driven pulleys were measured using a tiny load-cell inserted between two blocks and a telemeter system, under several constant speed ratios. Ring tension distributions were also measured using a specially devised block. From the experimental results, the following conclusions were drawn: (1) Block compression force distribution on the driving pulley is significantly different from that on the driven pulley. (2) Ring tension takes different value at each side of strings. It is considered that this phenomenon is caused by difference of saddle surface speed between two pulleys.