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DOI： 10.1299/jamdsm.2018jamdsm0048

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Inc.  

A laser microscope with a wide field of view developed in our previous study allowed us to observe the whole surface of a cylinder in a very short time. In that study, resolution of the laser microscope in the depth direction was sacrificed to obtain a wide field of view. To overcome this shortcoming and achieve nano-level measurement of 3-dimensional profiles of various objects, we have introduced two-beam interferometry to the wide field of view laser microscope. To achieve a high contrast interference fringe pattern, a glass reference plate was coated with a thin Cr film or other pure metals. The interference fringe pattern was distorted from sinusoidal wave into a sawtooth-like waveform. The distortion of the interference fringe pattern appeared to correspond to the inclination of the specimen surface measured. This shows the possibility of realizing a novel single shot interferometry method capable of determining the surface profile from only one image of the interference fringe pattern without using the phase shift method. The type of distortion of intensity distribution was different for each metal. The mechanisms by which the intensity distribution of the interference fringes changed to sawtooth pattern are discussed from both a Fourier-transform analysis and an electromagnetic approach.

DOI： 10.1016/j.precisioneng.2018.01.015

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

<p>This paper addresses a novel lightweight and low starting torque bearing with looped carbon fiber brush (LCFB). LCFB simulates bristle of living being. Moreover, the static friction coefficient is nearly equal to the kinetic friction coefficient. By applying LCFB to a slide bearings, where a shaft is supported by multiple LCFBs, it is realized low starting torque bearings as well as lightness compared to conventional ball bearings. In this paper, we manufacture prototype LCFB slide bearings. With the bearings, we compare friction torque between LCFB slide bearings, slide bearings and deep groove ball bearings. As results, the ratio of starting torque to regular torque of LCFB slide bearing is from 0.93 to 1.07 which is smaller than that of the slide bearing. When micro-spline shaft is used as a mating material of LCFB slide bearing, the torque reduces because of decrease of real contact area between LCFB and mating materials. In addition, since LCFB utilize elastic deformation of fibers, LCFB slide bearings are not endurable in heavy radial load as high as load rating of ball bearing. Therefore, we define the load capacity of LCFB slide bearing from buckling load of a carbon fiber bundle to avoid overload state. We propose the load capacity as a design guideline of LCFB slide bearings.</p>

DOI： 10.1299/transjsme.17-00252

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DOI： 10.2493/jjspe.82.976

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Penerbit UTM Press  

Diamond-like carbon (DLC) provide very excellence performance in term of friction coefficient and wear resistance under boundary lubrication. the nano characteristic of the transformed layer has not been studied in terms of its hardness which is believed to have a significant effect in the tribological performance. This study presented the scratch test of the DLC transformed layer was obtained from the AFM scratch test that governs the friction behavior of DLC. As a result, the hardness of the DLC transformed layer depends on the oil temperature, where the sliding interface of DLC softened during the friction test due to graphitization process.

DOI： 10.11113/jt.v78.9761

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

In this study, we theoretically and experimentally explore the acoustic leak of an entire acoustic system as well as the various gap occurring between a gasket and flange. We conducted the first-ever fundamental research related to sound transmission loss through a narrow gap between a gasket and flange. In the experiments, we constructed pipeline elements, including the gap and the leakage path, in the impedance measurement tube. In the theoretical analysis, we replaced the fluid path, including the gap, with acoustic elements that comprise an electrical equivalent circuit. We then conducted the analysis using the transfer matrix method. To calculate the attenuation of sound waves propagating through the gap, we considered friction in association with viscosity, primarily in the boundary layers of the inner wall, to derive the characteristic impedance and propagation constant. The trends between the calculated and the actual experimental values for transmission loss in the entire acoustic system coincided enough with regard to a large gap size range between 0.01 and 0.2 mm. Furthermore, the transmission loss linearly increased with the decreasing logarithm of gap for the calculated regions. Furthermore, the theoretical analysis and experimental results show agreement for incline gap conditions between the gasket and flange. The maximum gap also greatly affects the acoustic transmission loss for the inclined gaps. This was confirmed both by the experimental and the calculated values. We consider that these results provide fundamental acoustic knowledge specific to the narrow gap between the gasket and flange in an acoustic system.

DOI： 10.1299/jamdsm.2016jamdsm0067

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

An aneurysm clip is a medical instrument that is used intraoperatively to clip a ruptured cerebral aneurysm and reduce the risk of rebleeding. To prevent the clips from slipping off the aneurysm neck, it is very important to maintain a constant clamp force. A high frictional coefficient of the clip blades will also help prevent slippage between the clip blades and the blood vessel. In this study, to raise the frictional coefficients of the clip blades, we used a laser processing machine to produce clamp surfaces of the aneurysm clips with micro-dimples or micro-grooves. The static and dynamic frictional characteristics of the clamp surfaces made in this way were examined. The grooved surfaces with a width of 30 mu m and a groove pitch of 40 mu m showed the highest frictional coefficient. However, the dimpled surfaces with a shallow depth of 1 mu m showed lower frictional coefficients than existing aneurysm clips.

DOI： 10.1299/jamdsm.2016jamdsm0026

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

In a previous study, we developed a new method for observation of the whole cylindrical surface in a very short time,using a laser microscope with a wide field of view. When cylindrical specimens were rotated by a motor-driven rotary table, the focused laser light was scanned along a generatrix of the cylinder surface. Thus, the whole cylinder surface could be observed easily even over a very short time. As the obtained image was a developed view of the cylinder surface, it was easy to measure the distance between any two points on the cylindrical surface. In this study, we acquired interference images of the whole cylinder surface with the aid of a reference plane. As a result, fringe patterns over the whole cylinder surface could be obtained. From image processing of the fringe patterns, we calculated the nanoscale surface profile of the cylinder.

DOI： 10.2493/jjspe.81.699

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MALAYSIAN TRIBOLOGY SOC-MYTRIBOS  

Diamond-like carbons (DLC) with hardness of 47.1 GPa were coated on SUJ2 rollers, and their tribological properties were investigated after friction test under boundary lubrication conditions in an additive-free mineral-based oil at different testing oil temperatures of 24, 80 and 160 degrees C. From the results of the Raman analyses and Spectroscopy ellipsometry, we found that the structure changed of DLC at the topmost of sliding surface and their thickness will measured using AFM. It is found that the transformed layer increased with increases of testing oil temperature.

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Language：Japanese   Publisher：Japanese Society of Tribologists  

DOI： 10.18914/tribologist.60.02_90

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

In a dye-sublimation printer, a thermal print head presses and heats a dye-based ribbon to diffuse ink dyes to the desired positions into the receiving layer of paper. The print quality will deteriorate if the contact condition between the thermal print head and the paper is insufficient. Thus, it is necessary to analyze the contact condition for finer printing. Direct observation of the contact area with an optical microscope is effective to clarify the contact conditions of the thermal print head. However, conventional optical microscopes take too much time to observe the whole apparent contact area, because their fields of view are not sufficiently wide. Previously, we developed a laser microscope with a wide field of view and applied this laser microscope to observe the whole apparent contact area of rubber elements. In this study, we examined the contact conditions between the thermal print head and the paper. In general, when we observe the contact area of two solid surfaces, one is restricted to a transparent material such as a glass plate. Instead of the thermal print head, a glass head of the same shape as an existing thermal print head was pressed on the paper and observed through the glass head. This allowed us to clearly determine the contact situations of the interface and measure the contact widths and distributions of real contact area. In this method, it was confirmed that the contact width and the real contact area changed in accordance with the type of paper used, steps of the printing process, and density of color printing. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.triboint.2014.06.005

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DOI： 10.2493/jjspe.80.675

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

To quantitatively predict leakage rates through gasket/flange interface, it is important to observe contact conditions at seal surfaces because the leakage path consists of the non-contact portions between the flange and gasket surfaces. The contact surfaces of the flanges were finished by lathe turning. In this study, we observed real contact area on gasket surfaces using a laser microscope with a wide field of view. The observations indicated that the leakage paths on the gasket surfaces were in the radial direction perpendicular to a lathe-turned groove and the circumferential direction along the groove. As the closing loads increased, the leakage paths in the radial direction disappeared and only the leakage path in the circumferential direction remained. The critical contact pressure where the leakage paths in the radial direction disappear was determined from the observation of the contact surface of the gasket. Over the critical contact pressure, the leakage rates obtained from the experiments showed good agreement with the calculated values under the assumption of laminar flow along the turned groove. Under the critical contact pressure, the recalculated values considered the leakage paths in both the radial and circumferential directions approached the experimental values.

DOI： 10.1299/transjsme.2014dsm0173

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DOI： 10.2493/jjspe.80.302

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Analysis of contact conditions between rubber rollers and printing paper is important for stable paper feeding operation. Direct observation of apparent contact area is necessary to understand contact conditions, such as distributions of real contact area and micro-slips. However, conventional optical microscopy takes too long to observe the whole apparent contact area because the field-of-view is too narrow. We developed a wide field-of-view laser microscope, and applied it to determine the distributions of real contact area of rubber rollers against glass plates. Critical torques at which micro-slips of the rubber rollers occurred were proportional to total real contact area. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.triboint.2013.07.014

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASME  

To quantitatively predict the leakage rates of static metal seals, it is important to observe the real contact area at seal surfaces because the leakage path consists of the noncontact portions between the flange and gasket surfaces. In a previous study, we observed the real contact situation using a thin polymer film 1 mu m in thickness. In the present study, we observed the real contact area on gasket surfaces using a laser microscope with a wide field of view. With this method, observation time over the whole gasket surface could be greatly reduced compared with conventional methods. The observations indicated that the leakage paths on the gasket surfaces were in the radial direction perpendicular to a lathe-turned groove and the circumferential direction along the groove. As the closing loads increased, the leakage paths in the radial direction disappeared and only the leakage path in the circumferential direction remained. When the closing loads increased further, the widths of the leakage paths at both the inside and outside on the gasket surface became narrower. The critical contact pressure where the leakage paths in the radial direction disappear was determined from the observation of the contact surface of the gasket. The leakage rates obtained from the experiments showed good agreement with the calculated values under the assumption of laminar flow along the turned groove over the critical contact pressure.

DOI： 10.1115/1.4024781

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The Carbon Nanotubes have been reported to show hysteresis curves by Nano-indentation tests. To clarify the mechanism of this hysteresis, we conducted Nano-indentation tests to CNT films by using two diamond tips with different curvature radii. The AFM Nano-indentation was to perform penetration of diamond tip into CNT film, which means generation of friction force between diamond tip aspect and CNT tubes aspect. On the other hand, in the case of using spherical diamond tip by which cyclic Nano-indentation tests were conducted, the load-displacement curves became similar to those of carbonaceous coatings. This means that cyclic indentation for CNT made it like continues material. However, after several cyclic Nano-indentation tests to same position, the CNT specimen still showed hysteresis curve. These results indicated that hysteresis of CNT by Nano-indentation was related to friction between CNT tubes each other. © 2013 The Japan Society of Mechanical Engineers.

DOI： 10.1299/kikaic.79.1821

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Frequent contacts between bearing balls or needles and its guide generate friction heat, and it is not demanded because oil viscosity becomes low, then oil film thickness decreases. In such case, direct contact between mating surfaces occurs in the real contact area. To prevent wear by direct contacts, high wear proof and low friction coefficient of hard carbon coating is demanded. However, in the case of wear particles which are generated from hard carbon coating, the particles become wear promotion elements of bearing surfaces. Therefore, a surface shape modification is important to eliminate wear particles from contact area. In this paper, we prepared CNx (Carbon Nitride) coating deposited on surface with texturing to reduce friction coefficient by wear particles which were lied between mating surfaces. Friction tests were carried out at mixed and boundary lubrication condition with VG100 oil. We applied glass beads as imitation wear particles. In the boundary lubrication condition, the CNx coated surface showed friction coefficient of 0.058 in only VG100 lubrication. On the other hand, the friction coefficient was approximately 0.12 without CNx coating in VG100 lubrication. In the case of friction test with glass beads, it was clarified that 40 μm width and 20 μm depth texturing with 32 lines showed lowest friction coefficient when the specimen slid against counter material. © 2013 The Japan Society of Mechanical Engineers.

DOI： 10.1299/kikaic.79.3895

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The carbonaceous hard coating such as Diamond-Like Carbon is one of the materials to prevent surface damage. It was reported that Carbon Nitride (CNx) coating showed superlow friction coefficient when it slid against a Si₃N₄ ball in N₂ environment. In the case of applying CNx coating for industrial fields, it is necessary to improve adhesion between CNx coating and substrate. In this study, we clarify the effect of interlayer to improve adhesion of CNx coating to WC substrate. 4 different kinds of interlayer materials were prepared. From the scratching test results, adhesion of using CrN and no interlayer was smallest. On the other hand, SiN, CN and DLC interlayers showed high adhesion. From the finite element analysis, interlayer thickness and Young's modulus did not affect to improve adhesion between CNx coating and WC substrate.

DOI： 10.1299/kikaic.77.3502

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We report on an international cooperation between Nagoya University (NU), Japan and DLR Stuttgart, Germany on scaling issues in laser ablative propulsion. Lessons learned from collaborative work in the laboratory will be summarized with respect to the comparability of experimental methods and corresponding standardization issues. With the background of previous experimental research at the University of Alabama in Huntsville (UAH), experimental work with CO2 lasers in a moderate (NU) and high (DLR) pulse energy range on laser ablation of POM is presented. Profilometry results of target surfaces are compared with fluence distributions from beam propagation modeling. Ablation from flat targets is reported with respect to energy and area scaling and compared with results from ablative propulsion employing parabolic nozzles.

DOI： 10.1063/1.3657015

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One of the remaining unknown subjects of laser propulsion involves whether special benefits or challenges exist for applying laser ablation propulsion to targets with particularly large or small spot areas. This subject is of high importance for a wide range of topics ranging from laser removal of space debris to micropropulsion for laser propulsion vehicles. Analysis is complex since different ablation phenomena are dominant between atmosphere and vacuum conditions. Progress has also been impeded by the difficulty of setting control parameters (particularly fluence) constant while the spot area is adjusted. It is also usually difficult for one group to address small- and large-area effects using a single high-power laser system. Recent collaborative experiments on laser ablation area scaling at several institutions, using 100-J class and 10-J class CO2 lasers, have advanced the understanding of laser propulsion area scaling. The spot area-dependence of laser propulsion parameters has been investigated over an area range covering approximately 0.05-50 cm(2) at low fluence of about 0.6 J/cm(2). The experiments were conducted well below the threshold for plasma formation, and provide an estimate of the ablation threshold for CO2 laser ablation of POM.

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This paper shows the wear characteristics of carbon nanotube films made by surface decomposition of SiC. By this method, one can obtain remarkably high density of CNTs with well vertical alignment. For the purpose of measuring the wear characteristics of CNT films with submicrometer thickness, we carried out nanoscratch and nanoindentation tests by using an atomic force microscope (AFM). And we used 2 kinds of AFM cantilever tips with tip radii of about 20 nm and 150 nm. The experimental results showed wear behaviors of CNT films dependent on CNT length and normal load. And CNT films were worn gradually as the number of wear cycles increased. The effect of CNT length on wear of CNT films appeared as different behaviors of CNT films under normal load. That was originated from bending stiffness of each CNTs with different length as measured by nanoindentation. Shorter-CNT films had less wear because of higher deformation resistance than longer ones. Under the normal load, the SCD tip penetrated to several tens of nanometers in depth, but the CNT films showed only wear depth on the order of angstrom for each scratch cycle. Thus we confirmed that CNT films have both strength and flexibility, which reflects remarkable mechanical properties of CNTs. These results are important for machine designs using CNT films as friction materials.

DOI： 10.1299/jamdsm.4.373

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A CO2 laser was operated at pulse energies up to 10 J to ablate polyoxymethylene targets in air and vacuum conditions. Critical effects predicted by ablation models are discussed in relation to the experimental data, including specifically the threshold fluences for vaporization and critical plasma formation, and the fluence at which the optimal momentum coupling coefficient is found. Finally, we discuss a new approach for modeling polymers at long wavelengths, including a connection formula that links the vaporization and plasma regimes for laser ablation propulsion.

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The topic of area scaling is of great importance in the laser propulsion field, including applications to removal of space debris and to selection of size ranges for laser propulsion craft in air or vacuum conditions. To address this issue experimentally, a CO2 laser operating at up to 10 J was used to irradiate targets. Experiments were conducted in air and vacuum conditions over a range of areas from about 0.05-5 cm(2) to ablate flat polyoxymethylene targets at several fluences. Theoretical effects affecting area scaling, such as rarefaction waves, thermal diffusion, and diffraction, are discussed in terms of the experimental results. Surface profilometry was used to characterize the ablation samples. A CFD model is used to facilitate analysis, and key results are compared between experimental and model considerations. The dependence of key laser propulsion parameters, including the momentum coupling coefficient and specific impulse, are calculated based on experimental data, and results are compared to existing literature data.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)   Publisher：Japan Society of Mechanical Engineers  

Carbon nitride (CNx) coating is one of the carbonaceous materials, which was reported to show superlow friction coefficient (μ&lt
0.009) in Nitrogen environment. Therefore CNx coating is a promising material of solid lubricant for sliding interfaces to reduce friction. The superlow friction appeared after running in process of several hundreds of friction cycles and its mechanism has not been completely clarified yet. It was proposed that the soft thin layer generated on CNx coating after running-in process contributed to the superlow friction. However, the mechanical properties of the superficial layer of CNx coating such as hardness and Young's modulus have not been experimentally shown because of its small thickness estimated to be 10 nm or less. So we carried out in-depth measurements of mechanical properties of the thin layer on CNx film by nanoscratching test using an atomic force microscope. Then the existence of thin, soft layer on the top of CNx coating after running-in process was experimentally shown.

DOI： 10.1299/kikaic.76.3794

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Carbon nitride (CNx) coating is one of the carbonaceous materials, which was reported to show superlow friction coefficient (μ<0.009) in Nitrogen environment. Therefore CNx coating is a promising material of solid lubricant for sliding interfaces to reduce friction. The superlow friction appeared after running in process of several hundreds of friction cycles and its mechanism has not been completely clarified yet. It was proposed that the soft thin layer generated on CNx coating after running-in process contributed to the superlow friction. However, the shearing strength of the superficial layer of CNx coating has not been experimentally shown because of its small thickness estimated to be 10 nm or less. So we carried out in-depth measurements of the friction force of CNx film against a cantilever tip by nanoscratching test using an atomic force microscope. Then the existence of thin, low-shear layer on the top of CNx coating after running-in process was experimentally shown.

DOI： 10.1299/jsmemecjo.2010.8.0_231

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Tribologists  

Adherence of carbon nanotube film made by surface decomposition of SiC was studied. For this purpose we carried out scratch tests in nano- and microscale. By microscratch test, it was found that adherence at the interface was higher for CNT films with shorter CNTs and CNTs were not broken at the middle but removed from the interface. To clarify the dominant force (shear force or moment of force) which caused different adherence, we also carried out nanoscratch test by using AFM. In nanoscratch, AFM tip made of diamond coated silicon applied shear force to CNT films from lateral direction. And there was no significant change of adherence by lateral force (shear force at the interface). We conclude that bending-induced moment of force is dominant on the interface strength of CNT films.

DOI： 10.2474/trol.3.352

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It is difficult to separate small parts precisely from thin sheet metals by press blanking. This study describes a countermeasure to the problem by combining press forming and chemical etching. A 0.1 mm beryllium copper sheet was indented along a cut profile and subjected to etching, resulting in separation of the part surrounded by the indented line. Etching time to complete separation was considerably reduced compared with the ordinary etching process. Shape of indented portion also affected the etching time. Two indenting methods were tested in combination with two masking methods. SEM observation showed that every test condition provided a good cut edge having a smooth and fracture-free surface although some thickness reduction or dissolution of the cut edge occurred depending on masking methods. (C) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jmatprotec.2007.11.135

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DOI： 10.20549/jseeja.2017.0_290

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In electrophotographic printer, there are several processes of charging, exposure, development, transfer, fusing, and cleaning. As for the quality of printing, tribological factors associated with the rubber roller are important. We focused on the observation of micro-slip occurred between those rollers. However, the width of the contact is wide for commercial microscopes. Thus, we used the laser microscope which has wide field of view by installing low NA objective lens. Many micro contact points were observed and they were created by the small asperities on the rubber surface making contact with cylindrical surface of the smooth glass. Some torque was applied to the rubber roller, and each of the micro contact points slipped individually. The slip distance and the real contact area of each contact points were obtained. Comparing the new and aged rollers, we clarified the difference of micro slip distribution of the rubber roller.

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Nowadays the overturn and fall accidents of elderly people is becoming a frequent medical accident in Japan where the birthrate is falling and the population is aging. It can be suggested that one reason for the overturn and fall accidents of elderly people is the slipping between the road surface and the shoe sole. To clarify the contact mechanism between the shoe sole and the floor is important. In this study, we used a transparent silicone rubber and we assumed it as a shoe sole. We observed the real area of contact between a silicon rubber and the floor. By using a transparent rubber, we could make the contact interface between an elastic rubber surface and a rough surface of harder material. We found that a microscopic observation over 10mm wide range, which has been accomplished by the laser microscope with wide field of view, is important to output a reliable experimental result. We clarified an influence of the external normal force and a tangential force on a real contact area and mechanism of the slipping between the floor surface and the shoe sole.

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In electrophotographic printer, the toner is printed via several processes of charging, exposure, development, transfer, fusing, and cleaning. Maintaining a good condition of this printing system, a tribological factor associated with the rubber roller is one of the important factors. In this study, we focused on micro-slip distance and its distribution over the wide range of the contact area of a rubber roller. However, the whole area of the contact is too wide to observe with commercial microscopes. We used the laser microscope which has wide field of view by installing low NA objective lens. Half of the whole contact interface between a rubber roller and cylindrical glass surface was observed. In the high resolution image of the contact interface, we could see many contact points made by small asperity on the rubber surface making contact with cylindrical surface of the smooth glass. Applying torque to the rubber roller, each of the micro contact points slipped individually. The slip distance and the real contact area of each contact points depended on the position along with the rubber roller axis. Comparing the new and aged rollers, we clarified the difference of micro slip distribution of the rubber roller.

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In a previous study, a novel method for observation of cylindrical surfaces was developed with a laser microscope. With this laser microscope having a wide field of view, cylindrical surfaces can be observed by scanning the focused laser light along the bus direction and rotating the cylinder. However, there is a trade-off relationship between the field of view and the resolution in the depth direction, the resolution of laser microscope with wide field of view becomes low. In this study, we have supplemented the low resolution in the depth direction by introducing a reference plate. To clarify how the resolution in the depth direction is improved, small indentation marks were prepared on the cylindrical surface and were observed with the laser microscope. It can be said, by comparison with stylus profilometer that there were measurement errors less than 1μm. In addition, the cylindrical lens for which there have been almost no practical measurement method was also measured. The three-dimensional shape of the cylindrical lens was analyzed from the observation result and displayed in a computer screen.

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Selective laser sintering (SLS) is capable of modeling the complex internal shape. We have developed an implant material with complex internal shapes by utilizing this technique. In this study, SLS in two conditions, we compared the properties of the sintered product. It was a vacuum heating to the sintered product to increase the strength. As a result, increasing the amount of energy that is put into the powder layer, the Young's modulus is increased, and porosity and permanent strain is reduced. As a result of vacuum heating, the Young's modulus was nearly constant. In addition, strength was increased because the permanent strain is reduced. The entire sintered product is contracted when vacuum heating. However, increasing the amount of energy when the selective laser sintering, shrinkage has decreased

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Vertically aligned carbon-nanotube (CNT) film is expected as a superior low contact thermal resistance material. The microscopic deformation behavior of CNT in contact is clarified by previous study, but the difference in the deformation behavior when changing the length of CNT is not clarified. The vertically aligned CNT film was brought into contact with a plano-convex lens, and the contact surfaces were observed using a laser microscope with both high resolution and wide field of view. We clarified the difference in the deformation behavior when changing the length of CNT by analyzing states of the contact surfaces under various contact pressures. In each length of CNT, the relation of the intensity of reflected laser of 2-beam interference and contact surface pressure was elucidated.

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Aspheric lens mold requires high shape accuracy. However, there are few non-contact methods that can measure the entire surface of large mold in a short time. Therefore, in a previous study, a scanning laser interferometer with wide field of view has been developed with a reference plate introduced between a sample and the laser microscope with wide field of view. And a software program to interpret fringe patterns as 3 dimensional shapes has also been developed. With the reference plate with thin Cr film coated by ECR sputtering method, interference fringes in the form of non-sine waves were measured. In this study, attempts have been made to utilize the non-sine fringe patterns for more efficient shape measurement. Thus, we clarified the effect of the materials of metal films coated on the reference plates by fringe pattern analyses. The results of fringe observation and the analyses led to two conclusions. There are 2 typical fringe patterns which are determined by relative refraction index values of coating material to that of glass substrate. The latter is that the incident laser is multiply reflected between the reference plate and the observation object surface, and consequently, brightness distribution of the non-sine wave occurs.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

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Carbon nanotubes have been reported to have high thermal conductivity. A vertically aligned carbon nanotube (VA-CNT) film is composed of densely packed and highly-aligned CNTs on a SiC substrate. This VA-CNT film is expected to have superior heat conductivity than a conventional thermal-grease heat transfer method. However, it is not clear that how much contact pressure and contact roughness affect the contact thermal conductivity of the VA-CNT films. We developed an apparatus that measures the contact thermal resistance by an one-directional steady-state heat flow method. We found out that there was suitable surface roughness for the minimum contact thermal resistance of the VA-CNT film.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Vertically aligned carbon-nanotube (CNT) film is expected as a superior low contact thermal resistance material, but the microscopic deformation behavior of CNT in contact is not clear. The vertically aligned CNT film was brought into contact with a plano-convex lens, and the contact surfaces were observed using a laser microscope with both high resolution and wide field of view. We clarified the microscopic deformation behavior of the CNT by analyzing states of the contact surfacesunder various contact pressures. The surface of the CNT film has roughness. So, there was a gap between the vertically aligned CNT film and the plano-convex lens, which should be minimized to minimize the thermal contact resistance. The mean distance of the gap was estimated from the intensity of reflected laser of 2-beam interference, and we elucidated the relation between the mean distance and the contact pressure. The vertically aligned CNT film complicatedly deformed on a large-scale under very high contact pressure.

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Language：Japanese   Publisher：Japanese Society for Engineering Education  

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In a previous work, we developed a new type laser microscope that has features of confocal scanning type and wide field of view. This new type of laser microscope was applied to detection of micro/nano-fine flaws over a wide area of 8 x 10mm on metal or glass surfaces. Several micro fine flaws were produced on stainless steel by scratching the surfaces with a diamond stylus. The fine flaws on the metal surfaces were able to be seen through the laser microscope we developed. Furthermore, submicrometer-flaws were produced on Si substrate or cylindrical-glass surface by focused ion beam technique, FIB. The surfaces containing those micro/nano flaws were observed with the laser microscope and the flaws on the Si substrate could be seen. It can be said that the flaws on the glass surface is slightly difficult to observe than those on the metal surfaces due to the wavelength of the laser we used.

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The Carbon Nanotubes was reported which material showed hysteresis curve when it had been Nano-indentation test. To clarify the mechanism of this hysteresis, we prepared two different curvature radius diamond tips, and conducted Nano-indentation tests to CNT films. The AFM Nano-indentation realized penetration of diamond tip into CNT film, which means generation of friction force between diamond tip aspect and CNT tubes aspect. On the other hand, in the case of using sphere diamond tip, and cyclic Nano-indentation tests conducted same position, the load-displacement curve became similar to indentation test result of carbonaceous coating, it means that cyclic indentation for CNT made it like continues material. However, after several cyclic Nano-indentation tests to same position, the CNT specimen still showed hysteresis curve. These results indicated that hysteresis of CNT by Nano-indentation was related to friction between CNT tubes each other.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Carbon fiber is one of the candidates to make friction surface without coating. It is assumed that carbon fiber is consisted by carbon atoms, that's why it is able to make sustainable friction surface without lubrication, however, the tribological property of carbon fiber is not so clear. To clarify the tribological property of carbon fiber brash, we conducted friction test between carbon fiber and PTFE, aluminum alloy and brass alloy with different normal load. The carbon fiber was bind by heat shrinking tube, and then it was formed 6 mm diameter specimen. The carbon fiber brash showed almost same static friction coefficient ms and kinetic friction coefficient jxk, jxs/(ik was around 1 to 1.5. On the other hand, aluminum alloy and brass alloy showed the (is/fik ratio around twice rather than carbon fiber. The specific wear rate of carbon fiber was around 10^<-3> mm^3/Nm, that was larger than aluminum alloy, brass alloy and glass disk.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

In a production process of rail vehicles, several panels such as a ceiling panel and side panels are assembled by fusion welding. The welding heat causes the assembled vehicles to be slightly distorted. In the next interior fitting process of the rail vehicle production stage, a huge number of parts must be fitted, such as air conditioning units and frame bars for straps, etc. It is very difficult for those parts to be fixed into the railway vehicles since the bolt holes are not in right positions because of the welding heat. So it is of very importance to measure shapes of the panels and the bolt holes after the welding process. In a previous study, we had developed a new type of laser coordinate measuring machine with a laser distance meter and two galvano mirrors. In this study we have improved the measuring accuracy of the developed system with larger galvano mirrors.

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Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

Friction properties as initial and average friction coefficient were investigated for carbon brush materials. Experimental results shows that static friction coefficient of carbon fiber brush is smaller than kinetic friction after a macro slip. This phenomena is different from the usual friction properties between metals. I

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Other Link： http://hdl.handle.net/2237/23484

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

With the development of the grill roasted both face of fish, temperature in the grill exceeds 300 -C, and the use of the fluorine resin for grids, which are fish holder in the grill, becomes difficult because of heat resistance. After several uses of these resin grids, cooked fish easily adhere to the grids, and cooked fish surface and body remained on the grids which is new problem as worth outside looking and poor cleaning up. Therefore, it is necessary for grid materials to proof heat and low adhesion between cooked fish surface and grids. As a usual, the maximum adhesion force to peel off a fish from the metal grids, which are basic material for commercial grids, is the parameter to evaluate the surface of grids in the adhesion properties. However, such maximum adhesion force is not able to become basic physical data because it depends on the sequence of the peeling off the fish from grids and the fish has individuality of size and oil amount. One of the variation factors were suggested oil included in fish, therefore, we prepared fish protein water divided from oil by centrifuge. It was important to know actual contact area which was affected for adhesion force. Finally, we introduce energy release ratio calculated from adhesion force divided by contact area. As a result, the standard deviation of average adhesion force decreased from 69.5% to 8.5% to be introduced fish protein water, then, it decreased to 5.7% to be introduced energy release ratio.

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In the case of oil lubrication with low sliding speed under high load, the hydrodynamic lubrication barely occurs, causing the slid contacts between mating surfaces. This increases the friction and the wear of the sliding surfaces. To protect the surfaces in such severe conditions, carbonaceous hard coatings such as diamondlike carbon (DLC) or carbon nitride (CNx) coatings is well-known with their low friction and anti-wear properties. However, it is also known that those coatings are severely damaged due to the small particles generated by wear. Therefore, we proposed the CNx coatings with microgrooves to reject those wear debris. In this paper, we discussed the effect of microgrooves on the friction properties of CNx coating under oil lubrication with small particles.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Since the discovery of carbon nanotubes (CNTs), the remarkable mechanical properties such as high tensile strength, high flexibility, high heat conductance have attracted many interests. And the synthesis of high quality CNTs using various methods have studied. Kusunoki et al. have reported that CNTs with high-density and well-alignment are formed vertically on a silicon carbide substrate. CNTs on SiC substrate could be used for tribomaterial with high adherence because each CNT covalently bonds with the SiC substrate. Thus, we have studied about interfacial strength of CNT films made by surface decomposition of SiC by using atomic force microscopy. And considering the non linear bending theory on bending (or moment at the interface of CNT films), the wear mechanism was discussed.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Since the discovery of carbon nanotubes(CNTs), the remarkable mechanical properties such as high tensile strength, high flexibility, high heat conductance have attracted many interests. And the synthesis of high quality CNTs using various methods have studied. Kusunoki et al. have reported that CNTs with high-density and well-alignment are formed vertically on a silicon carbide substrate. CNTs on SiC substrate could be used for tribomaterial with high adherence because each CNT covalently bonds with the SiC substrate. Thus, we have studied about interfacial strength of CNT films made by surface decomposition of SiC by using atomic force microscopy. And considering the non linear bending theory on bending (or moment at the interface of CNT films), the wear mechanism was discussed.

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Since the discovery of carbon nanotubes(CNTs), the remarkable structural, electrical and mechanical properties as carbon material has attracted many researchers, and the synthesis of high quality CNTs using various methods have studied. Kusunoki et al. have reported that CNTs with high-density and well-alignment are formed vertically on a silicon carbide substrate. CNTs on SiC substrate could be used for tribomaterial as high friction or wear proof materials because each CNT covalently bonds with the SiC substrate. Thus, we have studied about interface strength of CNT film by means of the combination of AFM nanoscratch test and finite element analysis. From the result, we could assume that shear strength at the interface of CNT films was about 180 MPa. And it was no dependency on the length of CNT.

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