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A prediction method was proposed for crack initiation in one-piece type brake discs under extreme braking conditions. Braking tests under extreme loading conditions were conducted by using sample discs. The variations of internal temperatures and surface strains at several locations were measured by using thermocouples and strain gages. In order to obtain the S-N curve of the disc material, specimens with a hole in their center were used for the fatigue test in which an alternative strain was cyclically applied. The numbers of strain cycles, when a 0.3mm crack initiated from the hole, were analyzed by the Weibull plot. The maximum and minimum strains at the hole edge were estimated by calculation considering the temperature variation with respect to time as well as the strain induced by friction due to braking pads. The number of cycles corresponding to the strain amplitude range was estimated by the rain-flow method.

The mechanism of permanent deformation of pressure plates has been investigated under very severe conditions, which are used for automobile clutches. Sliding tests were performed, where an extreme overload was applied to the pressure plate. It is found from the test results that the residual stress in the circumferential direction varied from compression to tension after the sliding test near the sliding surface of the plate. FE (Finite element) calculations were also conducted taking both plastic deformation of the plate due to thermal expansion and geometrical non-linearity into account. The FE calculations agreed well with the experimental results. The permanent deformation mechanism for pressure plates was summarized as follows. Compressive yielding of the plate occurs at the heating stage near the sliding surface. The residual stress in tension appears in the sliding surface when the plate becomes cool, and it deflects the plate like a bowl.

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.

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.

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.

An implicit finite element (FE) model was developed to accurately analyze the power transmitting mechanisms of CVT using a dry hybrid V-belt. The numerically analyzed results well agreed with the experimental results. The effects of angle mismatching of pulley groove and flange deflection on the power transmission were examined by using the present approach. The calculated results showed that the blocks were subjected to an over-load due to the pulley flange tilting. The angle mismatching between the pulley groove angle and the block wedge angle strongly affected the power transmission at both steady and transitional states. It was also found that the block tilting in the pulley groove affected the power transmission.

In order to reveal the shifting mechanisms for CVT using a metal pushing V-belt, three shifting rates were introduced. The belt motion in the pulley groove was also characterized using mean coefficients of friction as parameters, which identify the slippage condition of the belt in the pulley groove. The experimental results showed that one of shifting rates, dR/ds was almost constant in the narrowing pulley regardless of both rotational speed and transmitted torque. Here, R is the belt pitch radius in the pulley and s is the length measured along the belt pitch line. This fact indicates that the shifting is primarily governed by elastic deformation of blocks of the belt. Power transmitting states were also evaluated using a different type of lubricating oil whose nominal coefficient of friction was higher than that for the conventional AT oil. The observed mean coefficients of friction vary due to oil although the basic response of the CVT unchanged.

Creep tests under three-point bending loading were conducted at elevated temperatures for long glass fiber reinforced polypropylene in order to examine the effect of maleic anhydride modification for polypropylene matrix on the creep resistance. The high acid modification (1 wt%) significantly reduces the creep deflection at both low and high sustained loads. The residual tensile strength after 1000 hours creep also increased with an increase of maleic anhydride content. AE observation indicating an occurrence of debonding decreased with increasing acid density. The fractured surfaces show that the interfacial strength between glass fibers and matrix can be increased owing to an increase of maleic anhydride fraction.

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.

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 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.

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.

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.

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.

Block compression force and ring tension of a metal pushing V-belt type CVT have been experimentally measured at steady states. The peculiar transmitting mechanisms for this type of belts has also been outlined based on the experimental results in the previous works. In this paper, other forces simultaneously acting on a block at steady states were measured using newly developed devised blocks. These forces are frictional force between blocks and rings, normal force between blocks and pulleys, frictional forces between blocks and pulleys in radial and tangential directions. The transmitting mechanisms for the metal pushing V-belt type CVT were drawn in detail based on new experimental data. The following conclusions are emphasized in the present work. (1) A cohesive point where the block coheres with the ring exists in the pulley having a larger pitch radius at all conditions. This is not dependent on speed ratio and transmitting torque.

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.