Recently, steels of SUJ2, SUJ3 and ceramics are mostly used as bearing materials. However these materials can't meet all industrial environments. Furthermore, lubricating oil is not applicable to low temperature, high temperature and vacuum environment. Resin bearings improve machine life, because they can be used without lubrication. We investigated the relationship between load, rotation speed and wear loss in All-PEEK and PEEK race-PPS retainer hybrid polymer bearings under dry rolling contact fatigue.

In order to improve the reliability of the machine it is important to reduce the machine failure and extend the life of the hydraulic equipment used. Nowdays, oil deterioration diagnosis is carried out by analyzing oil sampled when changing oil, but in order to investigate the cause of failure of the machine, a diagnostic method that capable of constantly monitoring the deteriorated state of hydraulic fluid at the site is required. In this research, we aimed to verify the applicability of the on-line type colorimetric device on the actual machine and to clarify the correlation between the colour parameter of the oil and various characteristics, thus investigate the change with time of the oil used on the actual machine by various analysis methods. We also investigate the change in oil when mixed in with a new oil and clarify its correlation with colour parameter.

Cleavage of hydrocarbon in the initial stage of oil degradation is caused by heat and mechanical shearing. However, recently it has been suggested that electrostatic discharge has a possibility of cleavage of hydrocarbon. Most of machinery has a filtering system in order to filter contaminations in oil. It is found that electrostatic discharge occurs during oil filtration and then the oil is degraded. However, this mechanism has not been elucidated. Therefore, the purpose of this study is to quantify static electricity during oil filtration and elucidate its mechanism. We used test equipment assumed filtering system of machinery, and measured electrostatic voltage of middle of filter holder while changing the parameters of pump flow rate, oil temperature and oil conductivity. As a result, it was found that static electricity during oil filtration increased with increasing of flow rate, and decreasing of oil temperature and oil conductivity. Then we discussed the relationship between static electricity and flow rate of exit.

In this study, the friction behavior of texture surface by wet blast technique was investigated. The test slurry, which is pure water containing spherical zircon particles with an average diameter of 34.2 μm, is jetted on surface of the specimens at high velocity. Influence of dimple area of the texture surface on friction behavior at low sliding velocity was investigated by using ball-on-plate reciprocating friction tester. As a result, it was found that the texture surface consisted from the dimple area of 20-35 % was the most effective for low friction behavior.

Tread patterns of the tire are said to be the face of the tire. In addition, both the attractive design and advanced features are required. Furthermore, in order to exhibit high grip performance in terms of function, it is important to elucidate the proper correlationship between the surface strain, friction coefficient and actual contact area. Moreover, it is also necessary to balance the drainage control as a role of the tread pattern and the reduction of the tire noises generated by attaching the grooves. The purpose of this study contributes to the function evaluation of tires, and tries the improvement of function by investigating the proper condition of strain, friction coefficient, actual contact area related to the grip force of the tire. Furthermore, sound noise is also demonstrated by the numerical fluid analysis. This report describes the results of strain and friction coefficient using the prototype device of simultaneous measurement system of strain and friction coefficient, and the actual contact surface of the tire using transfer method and evaluating drainage and noise of tire by the numerical fluid analysis.

Magnetorheological elastomer (MRE) is a smart material that can change its stiffness depending on magnetic field. The main objective of this paper is development of a multi-layered isolator having self-sensing property using MRE. Conductive elastomer is the conductive silicone rubber. Its electric resistance can be changed by its deformation. It is assumed that its electric resistance indicates displacement of vibration using this electric characteristic. However, we have to investigate its electric characteristic to use conductive elastomer for self-sensing property. Therefore, this paper examines the electric characteristic which conductive elastomer has. We measure its magnitude of the impedance and its phase difference when the conductive elastomer is compressed. As a result, its magnitude of the impedance is linearly reduced as the compressive deformation is increased. Further, all measured phase difference are small enough to use as a sensor. Therefore, it is possible that conductive elastomer is used as a sensing property.

In this study, we made the acoustic meta-materials. When sound pass a material having high density, it has the property that sound velocity becomes fast. We thought that it enables the inclination of the sound by using this property. Therefore, we devised acoustic meta-materials that keep a change of the density in it. At first, we devised the acoustic meta-materials of three pattern. First pattern is slit form. Second pattern is disposition of square prop. Third pattern is disposition of cross prop. We analyzed them using limited analysis software. It can analyze in two dimensions. In the analysis, three fields are made that the sound wave spread field, the field that incorporated acoustic meta-materials, the field that is after a sound passes it. The expression to give a sound wave is sin2π/λ(x-ct). λ is a wavelength, x is displacement, c is sound velocity. From the result of the analysis, we understood that the square prop affected the inclination of the sound most. Then, we made a 3D model. All the materials of the part are the acrylic. In future, we really produce it and going to test in the anechoic room.

Lead free solder materials have been widely used for electric circuit boards. Solder joints have the possibility of open due to fatigue damage under thermal cyclic load. In our previous study, it has been shown that the low cycle fatigue live of the lead free solder materials depended on strain rate or waveform of the materials used by the fatigue tests and It was considered that damage recovery occurred under compressive stress. In this study, hourglass test pieces, which could avoid buckling under compressive load were supplied to the low cycle fatigue tests instead of usual cylindrical test pieces of Sn-3.0Ag-0.5Cu in order to establish an experimental method for confirming directly damage recovery under compressive stress. As the result, the break definition based on 8% load drop condition with hourglass test piece continued to keep conventional fatigue curve obtained by 25% load drop with cylindrical test piece.

In this work, the propagation behaviours of naturally initiated small crack in a polycrystalline Ni-base superalloy under the several kinds of TMF conditions were studied. The effect of phase angle between temperature and strain cycles in TMF loading on the propagation behaviour of small crack was discussed. The experimental results revealed that there was little influence of the phase angle on the small crack growth rates except the -90 degree condition when the crack growth rates of naturally initiated small crack are correlated with fatigue J-integral range.