We have developed a walking assistance device using an orthosis for neuro-rehabilitation of hemiplegic patients. In clinical trials, the users including MD and PT requested as follows: 1) Low cost (because an orthosis is generally expensive), 2) Adjustable for various users, 3) Easy to bend at the toe (because the sole of orthosis was made of hard plastic), 4) Can grasp the sole pressure without fail (inner sole type pressure sensor was apt to keep on pressing). To address these problems, we developed novel type of the walking device enabled to attach under the user's shoes directly, without using an orthosis. The soleplate of this device under the toe was configured the flexible rubber plate, therefore the user enabled to kick by his/her toe at the end of stance phase. Furthermore, this device equips four pressure sensors to evaluate user's gait posture precisely, and it can be diagnosed user's condition of bone alignment of the leg, e.g., varus or valgus knee. We can therefore suggest the feasibility of this device for gait training of hemiplegic patients using this diagnose method.

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The copper electroplating stress measurement method utilizes the grain growth in the copper on a machine element that has been subjected to repeated loads. Since the grain growth is also caused by thermal energy, an effect of ambient temperature on grown grain density and grain orientation was investigated. Cyclic torsion tests were carried out at temperatures from 293K to 353K. The relationship among grown grain density, maximum shearing stress, number of cycles and ambient temperature was formulated to measure the maximum shearing stress occurring on the machine element. Moreover, the cyclic bending-torsion tests were also performed and the orientation of grown grain was analyzed by EBSD. The slip direction of grown grain corresponded closely with the direction of maximum shearing stress in spite of ambient temperatures. This means that principal stresses can be measured using the pole figure of grown grains at temperatures up to 353K.

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The superlow friction mechanism of CNx (Carbon Nitride) coating slid against Si_3N_4 ball in N_2 gas was suggested to be taken place when the topmost surface of CNx changed to graphitic structure. It was assumed that ultraviolet ray (UV) could break C-N single bond when the ray power exceeded C-N single bonding energy, and we hypothesized that UV irradiation could make the CNx coating topmost surface graphitic without friction in N_2 gas. We carried out preparing the CNx coating irradiated UV as 254, 312 and 356 nm wavelength in air, Ar, N_2 and O_2. These specimens were analyzed by AES and XPS, It was found that the average N/C ratio of CNx films ultraviolet irradiation in O_2 was reduced by 60 percent. N-C and N=C were reduced to half, N-N/N-O was not changed. From AFM images, there was no effect of etching with ozone generated by the UV excitation of oxygen.

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Additives are components of lubricants. According to the required function, additives have a lot of species. Oiliness additives belong to one of these species. The required function for oiliness additives is the friction reduction under boundary lubrication. It is considered that the friction reduction is derived from adsorption layers which are constructed by the molecules of the oiliness additives. Huge amount of previous papers reported that there is the relationship between the friction reducing effect and the molecular properties. However, the evidence of that relationship was the results from macro-scale friction tests, in spite of that the scales of adsorption layer and molecules are nano-scale or angstrom-scale. Hence, we think that the discussion about the effects of the mechanical properties of adsorption layers on the friction reduction is insufficient. In this study, the relationship between friction behavior in micro-scale and nano tribological properties about the adsorption layers was investigated. Stearic acid and Decanonic acid were used for the oiliness additives. The adsorption of the oiliness additives was measured by Quartz Crystal Microbalance (QCM). Atomic Force Microscope (AFM) was used for observation of the several properties about the adsorption layer and the nano-tribological behavior. And the nano-tribological behavior was compared with the results of the micro scale friction test. From these results, it was observed that the stearic acid constructed the adsorption layer, and the layer of the stearic acid had the friction reducing effect. Finally, correlation of the tribological properties between the micro-scale and nano-scale was found. Similar behavior about friction force was shown in nano- and micro-scale.

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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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The purpose of this research is to develop a novel infusion pump using shape memory alloy (SMA) actuators. Conventional infusion pumps are the type of motor-powered pumps. The pump is commonly used for giving fluids intravenously. However, the motor causes a noise and a vibration. In a medical field, these phenomena maybe give a user such a patient a discomfort feeling. Therefore, we focus attention on SMA actuators instead of motors. SMA actuators have many advantages such as low mass, flexibility, small size and silent drive. In this paper, we report the driving principle, the structure and fluid transportation method of this pump. SMA actuator was made to memorize in the shape of a coil and we fabricated a SMA actuator unit by bundling its ten actuators. The developed pump was controlled fluids by moving three fingers that are actuated by the unit. As the experimental result, we confirmed that fluids were pumped at a maximum flow rate of 0.10 ml/min.

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Hydrodynamic thrust air bearings have a lot of advantages such as low environmental load, low frictional loss and maintenance-free and so on. However, bearing stiffness of the bearings is considerably low because the viscosity of air is very low. To solve this problem, optimized bearing was developed for the purpose of bearing stiffness maximization. As a result, it was confirmed that the bearing stiffness of optimized thrust air bearing is improved. However, it is not still verified that optimized bearing has high impact resistance against an external force. In this study, we conducted the impact experiment to the optimized bearing and a spiral groove bearing, and verified experimentally the impact resistance. Moreover, we compared the experimental results with the theoretical values to confirm validity of experiment. As a result, it was confirmed that the optimized bearing has high impact resistance and damping property compared with spiral grooved bearing. Also, the theoretical value and experimental values showed approximately agreement.

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Early fatigue damage in magnesium alloy was investigated under cyclic torsion. First, the angle between the longitude of the specimen and the slip line that occurred at the specimen surface was measured after a cyclic loading test. The angle was also calculated from the crystal orientation analyzed by using electron backscatter diffraction. The calculated angle agreed well with that obtained from the experimental results. This means that a Schmid factor is responsible for the formation of slip lines. On the other hand, the slip line was not observed in many crystals, even though the Schmid factor in theses crystals shows large value. These results suggest that an additional factor except for Schmid factor might influence the formation of slip lines. The angle between the slip direction and the specimen surface was calculated and it was recognized that not only the Schmid factor but also the angle affects the slip line formation.

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Cryogenic temperature is very low temperature under 20K. The goal of this research is to realize an ultrasonic motor which can be used in this cryogenic temperature. When the temperature decreases from room temperature to an ultralow temperature, a thermal stress is generated. By this stress, the ultrasonic motor breaks down or the performance is decreased. The purpose of this research is to reduce the thermal stress in the ultrasonic motor. A bolt-clamped Langevin-type transducer (BLT) is used as a transducer for the ultrasonic motor. The BLT is mainly made of invar (Fe Ni alloy). Invar has a coefficient of thermal expansion near to that of lead magnesium niobate-lead titanate (PMN-PT) single crystal. We have evaluated the thermal stress in the BLT from 300K to 4.5K. Additionally, the thermal stress in the BLT made of invar was about 50% of that in the BLT made of SUS304.

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The dragonfly wing is passively deformed under flapping, simultaneously has the strength to withstand high flapping frequency. These characteristics of deformation and vibration of the wing is important for dragonfly flight. However, the effect of that on a dragonfly flight has not been well understood. In this study, for the purpose of investigating an artificial wing suitable for flapping micro air vehicle, we measured natural frequency and deformation in flapping of dragonfly wing and fabricated the artificial wing based on the results of that. From the results of measurement, the dragonfly wing has the high natural frequency of 120Hz. Moreover, although base-side of the wing is hardly deformed, the tip-side of the wing is greatly deformed because of the torsional deformation from the nodus of dragonfly wing. Then, we fabricated the deformable artificial wing which deformation is the same as dragonfly wing and measured aerodynamic force and power consumption under flapping. As a result, the power efficiency of aerodynamic force when using the deformable artificial wing is 5 times greater than the power efficiency when using an undeformable wing.

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At present, many gears have involute tooth profiles which are easy to manufacture and are able to maintain constant gear speed even when the center distance changes. However the involute tooth profile has some disadvantages: it causes a high contact stress by meshing with two convex surfaces, and it also generates an undercut when gears have a small number of teeth. On the other hand, a cycloid tooth profile gear is also able to transmit a uniform motion. The cycloid tooth profile gear has greater tooth surface strength (except at the pitch point) due to the mesh with the convex and the concave surfaces, and it also has high bending strength. In this study, we investigated the wear of a cycloid tooth profile gear, using a power circulating-type gear testing machine, and measure the change in tooth profile of the test gears. Furthermore, we develop a computer program to predict the amount of the wear on the tooth surface for the spur gears. The method employs two equations: one based on Soda's wear model under lubricated condition; the other derived from the ploughing wear model. Using these equations, the wear depth on the tooth surface was calculated with changing of the contact stress, the sliding velocity, the oil film thickness, etc. The calculated value of the wear agreed with the experimental result.

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A pinion and a gear of a pair of spur gears usually have different the maximum root bending stresses because of using profile-shifted gears or thin-rimmed gears or internal gears. Because of inequality of the maximum root bending stresses, load-carrying capacity of the gear with smaller root bending stress is limited by the gear with larger one. If this limit can be removed, this pair of the gears can have greater load-carrying capacity than it has before. So, this paper presents an idea to remove this limit through designing a pair of spur gears with uniform maximum root bending stresses. It is realized through changing the tooth thickness of the racks on the pitch lines from a standard tooth thickness into a non-standard one. Tooth root stresses and surface contact stresses of a pair of spur gears with standard and non-standard tooth thicknesses are analyzed by loaded tooth contact analysis using the finite element method (FEM). Calculation results show that the load-carry capacity of the pair of the gears become greater when the pinion and the gear have the same maximum root bending stresses.

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Root stresses of thin-rimmed helical gears with symmetric and asymmetric web arrangement of helix angle β_0=20° were measured from the beginning of engagement to the end of the engagement by using the strain gauge method. The effects of rim thickness, web thickness and web structure on the root stresses, the maximum root stress and the worst meshing position, where the maximum root stress (worst loading position) occurs, were clarified. Bending fatigue tests were carried out, and then bending fatigue limit load and the effects of rim and web thickness on bending fatigue strength and bending fatigue crack were determined.

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We developed a new diagnostic method by using laser beam. The tooth surface is irradiated by zonal laser beam from oblique direction, and then irradiated laser beam line is shifted along the height of the tooth according to gear revolution. The variations of laser reflection between the initial and the present conditions are compared, and it can estimate a condition on a tooth surface such as initial or abnormal abrasion, pitting, etc. We developed a method of automatic and remote damage diagnosis on a gear tooth surface. By using this method, we can estimate and diagnosis automatically in consideration of influence of adjacent teeth by using an ideal measurement voltage based on each gear geometry. Moreover, by having devised more diagnosis methods in addition to this technique, use for various uses was attained as a simple diagnosis method of the damage on a gear tooth surface.

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We reported that the failer mode of the plastic crossed helical gear under grease lubrication condition is tooth breakage. Moreover, meshing teeth temperature of crossed helical gear consists of plastic and metal gears under no-lubrication condition can be evaluated by the mean flash temperature. In this study, the meshing teeth temperature of the crossed helical gear consist of plastic and metal gears was investigated experimentally. Experiments were carried out under grease lubrication condition. From the result of the experiments, we obtain the following results; (1) With regard to the crossed helical gear consists of plastic and metal gears under grease lubrication condition, the effects of the operating conditions and axial angle on the meshing teeth temperature can be evaluated by the mean flash temperature. (2) Meshing teeth temperature of crossed helical gear consists of plastic and metal gears under grease lubrication condition is lower than meshing teeth temperature of crossed helical gear consists of plastic gear under grease lubrication condition.

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Gears with a different tooth profile from an involute curve might be effective for the reduction of energy loss in the running condition. Sine-curve gears, of which teeth surfaces are formed using a sine-curve rack, have smaller sliding between tooth flanks than involute gears. The present paper describes the tooth surface temperature and the power transmission efficiency of plastic sine-curve gears. The running tests for sine-curve gears and involute gears were performed under various running conditions. Test results showed that the power transmission efficiency under no lubrication of a sine-curve gear is higher than that of involute gears..But that under grease lubrication is almost equal to that of involute gears.

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Plastic helical wheels are usually used as wheels meshed with a worm. The meshing between a helical wheel and a conventional worm is of a point contact, and the strengths of plastic helical wheels are considered to be lower than those of worm wheels which mesh at line contact with a conventional worm. By using a line contact worm gears, the higher strength is expected. In this paper, worms which mesh at line contact with helical wheels were developed, and the strengths of plastic helical wheels meshed at line contact with a worm were determined.

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The present paper describes simulation of spiral bevel gear tooth flank generation using CNC general purpose machine, and prediction computation of tooth contact patterns of these gear pairs, and estimation of effects on tooth contact patterns of machine settings such as vertical and horizontal using prediction computation. In the present paper, zerol miter gears which are kind of spiral bevel gears were focused. Tooth contact patterns were predicted by calculated distance between points on a gear tooth flank and the intersected points on the other gear tooth flank, which lie on normal from points on a tooth flank. As a result, tooth contact patterns on convex side moved from toe to heel side with increasing vertical and horizontal.

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According to the previews report, influence of alignment error and manufacturing error in face gear engagement was reported. Although many face gears are used for the fishing spinning reel, the time required for adjustment during the assembling of a reel has been increasing when the tooth flank was not modified. According to this report, it was shown when a tooth flank modification with transmission error (TE) controlled curve was applied to a manufactured tooth flank, and the influence of alignment error has been decreased. In the previous research, those factors of manufacturing error were considered in the assembly error. At the result, it was confirmed that tooth flank modification with TE controlled curve has big influence against "pressure angle error on pinion gear", "pitch error on face gear" and "rotational error on face gear". On the other hand it is well known that, there are two types of interference, namely, "interference of tooth tip" and "interference of tooth root" on face gear engagement. However these are interferences that occur when a face gear and a pinion gear are in contact on the pitch circle (reference position). While advancing this research, a new type of interference was discovered during this research. The interference occurs when a face gear and a pinion gear are in contact with an alignment error and manufacturing error. Therefore, tooth flank modification with TE controlled curve needs to take into account this interference. Otherwise, this modification may risk worsening the feeling instead. In this research, this new interference is also discussed. In this report, it is shown that result of investigation on mechanism of interference by alignment error and manufacturing error. Finally, the actual sample was measured in the combination of these error, and it is found that there is a possibility of a occurring this interference.

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The conical involute gears have been applied to automotive parts such as FR-4WD transfer. To apply for automobile, high capacity, higher quietness and efficiency are required. However the tooth contact of conical gear pair is point contact, so the large ease off happens even though each tooth surface has no manufacture error. Also the tooth depth and thickness of conical involute gears change along the lead direction. These characteristics have to be considered for the tooth mesh analysis. We have already published the transmission error analysis and tooth surface durability analysis considering these peculiar characteristics. In this paper, we develop the mesh efficiency analysis and show the improvement method of mesh efficiency by tooth surface modification. From this investigation, it is found that the mesh efficiency of conical involute gears is better than cylindrical gears due to the peculiar ease off shape.

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In order to investigate shot peening on rolling contact fatigue lives of bearing steel, fatigue tests were performed with a thrust testing machine and a roller testing machine. The disks and rollers were treated by shot peening with a shot diameter of 0.05mm. The surface hardness and the surface compressive residual stress of the test specimens were increased by the shot peening. The rolling contact fatigue lives of the test specimens treated by the shot peening were longer than that of the non-peened test specimens. The rolling contact fatigue lives of the disk specimens were improved by the increase in surface hardness due to the shot peening.

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In order to prevent environmental pollution in the manufacturing process and to obtain high load-carrying capacity of the power transmission gears, the tooth surface-finishing methods using volcanic-ashes were investigated. First, case-carburized test rollers were finished by cylindrical grinding machine. Secondly, the ground surfaces were finished by using volcanic-ashes. Third, the influence of surface texture on surface durability of test rollers was examined using a 2-roller-type fatigue testing machine. For test rollers with finished surface, the following results are obtained under the heavy load conditions: The surface temperature occurred by friction is low. During running, the amount of wear and the number of pits decrease. From these considerations, it is found that the surface finished by use of volcanic-ashes containing various chemical compositions is smoother than ground surface. Furthermore, in the case of the alloy steel of the same quality and same process of case-carburizing, surface durability of case-carburized gears is improved by using volcanic-ashes.

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The design for pitting (rolling fatigue) of rolling-sliding contact surface under mixed lubrication condition is based on the combination of maximum contact pressure (Hertzian stress) and lubrication condition (ratio of surface roughness value and oil film thickness value). But there is indirect relationship in the combination of contact pressure and lubrication condition to the pitting phenomena. The origins of rolling fatigue pit are the micro cracks in contact surface due to tangential force. In this paper, the pitting test results are re-examined from a standpoint of influence of the tangential force on pitting. The new parameter f(p_H/H_B)^2 based on the friction coefficient estimation formula by Matsumoto for pitting design is introduced. And it is cleared that the new parameter has same value to every different contact pressure and lubrication condition. In conclusion, it is necessary to reconsider the pitting design method for power transmission gears excepted tangential force from consideration.

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This report outlines that investigation conducted on the OBD stock removal, influence on honing stone breaking by burr of tooth edge, mass productivity and gear noise, in order to eliminate gear shaving process by high-speed synchronous gear honing. As a result of the investigation, it was verified that high-speed honing condition can be decided if the normal base stock removal per work revolution was used. In addition, it has been confirmed that burr of tooth edge have no influence on honing stone breaking and gear accuracy, besides the noise level of this honing gear is same as honing gear which has gear shaving process.

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For measurement of transmission error of micro gear, it is necessary to utilize a couple of micro rotary encoder whose diameters are smaller than the reference diameter of micro gear to be measured. The focus of this article is to develop and manufacture radial grating patterns for such grating disks of micro rotary encoder. The designed grating disk has 500 ^m in diameter and the number of gratings is up to 5,000. It was manufactured with nanoimprint technique with a silicon master mould which is developed by EB lithography technique. The precision measurement and analysis was carried out on the shape of the surface at the nano level using AFM. It was almost homogeneous with enough profile height accuracy and it was possible to detect a continuous signal of grating disk.

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An elliptical gear is a mechanism which transmits a non-uniform rotation as well as a cam. Because of the non-uniform rotation of non-circular gears, the torque varies significantly, causing an increase of dynamic vibration and noise. In this study, we investigated the vibration characteristics of two elliptical gear pairs: a single elliptical gear pair and a double elliptical gear pair. The torque variation of the shafts, the tooth root stress of the gear, the angular motion of the shafts, and the circumferential vibration acceleration of the test gear were measured by a running test. Furthermore, a program to calculate the vibration of the testing machine with the elliptical gear pair was also developed, and calculated the torque variation of the shafts, and the circumferential vibration acceleration of the test gear. Then, the results calculated by the program and the experimental results were compared to confirm the validity of the program.

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Cam profile has been determined from a three-body vibro impact system which is designed to be realized Grover algorithm to reduce residual vibration on a cam follower. Two among three oscillators are considered to be virtual to derive the functions of enforced displacement. Energy transfer from the cam follower to the virtual oscillator controls position and speed of the modal mass of the follower by using Grover algorithm. The obtained cam profile is continuous but non-smooth curve. Perfect remove of the residual vibration has been achieved with these cams.

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Chain drives transmit power parallel, well-spaced shafts, usually with a major change in rotational speed and torque. In order to design chain drives, we have to consider two problems. They are the fatigue of chain and the mating noise between chain and sprocket. In this study, we focused on the bulk temperature of chain and efficiency of chain drives. From the experimental results, we obtain the follows; (1) The proportion of increase in bulk temperature decreases with increasing rotational speed. (2) The efficiency of chain drives increases with increasing torque.

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Authors designed and produced a low cost device for linear drive system composed two unit bar and ferromagnetic pole-piece. The plate magnets in two unit bars are arranged in series, one plate magnet in drive unit bar is 10mm in length, width and 5mm in thickness. Another plate magnet in driven unit bar is 30mm or 60mm in length, and 10mm in width and 5mm in thickness. The linear drive system was succeeded in driving with gear ratio 1/3 and 1/6 under non-contact condition. Though there was a large difference 20% of gear ratio between designed and measured by cogging force, the measured maximum transmission normal load is 40N under gear ratio 1/3, driving speed 10m/min. And the maximum transmission normal load increased with decrease width of pole-piece. In addition, the width of pole-piece has the highest impact on the transmission normal load of all parameter, such as thickness of plate magnet and air gap between magnet unit bar and pole-piece.

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It is known by past researches on the loosening of a screw that rotation of loosen will arise if the radius direction vibration is given to a bolt head or the bearing surface of a nut. On the other hand, it is known that it is effective in ultrasonic vibration reducing apparent friction, and the method of performing screw tightening with little variation is also studied, it is performed by tightening with the ultrasonic vibration. In use of ultrasonic vibration, a stronger effect can be acquired by using resonance. In this research, the Machine Screw was fastened with axial ultrasonic vibration by vibration resonance, and it is investigated about the effect.

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It is known by past researches on the loosening of a screw that rotation of loosen will arise if the radius direction vibration is given to a bolt head or the bearing surface of a nut. On the other hand, it is known that it is effective in ultrasonic vibration reducing apparent friction, and the method of performing screw tightening with little variation is also studied, it is performed by tightening with the ultrasonic vibration. In use of ultrasonic vibration, a stronger effect can be acquired by using resonance. In this research, the bolt head or the nut was fastened with axial ultrasonic vibration by vibration resonance of Cross-shape Oscillator, and it is investigated about the effect.

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The machine screws are used for a lot of manufacturing products. A lot of researches have been carried out on the self-loosening of bolt nut joints under transverse vibration However, few investigations have ever been carried out on self-loosening of machine screws . The purpose of this report is to obtain basic loosening characteristic information about this problem. This paper reports how the lubricant or the lacquer painting film influences self-loosening when the truss head machine screw is used. As a result, the bolted joint that painted the lacquer film bearing surface showed it was loose easily by the experiment. The reason that comes to loosen easily is that the lacquer painting film is stripped off by the vibration.

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Bulk metallic glass (BMG) has unique mechanical properties, combining high strength and low Young's modulus. By applying BMG to the fabrication of fastening bolts, high resistance against bolt loosening is expected. The authors have developed hexagonal cap bolts made of zirconium-based BMG by cold thread rolling. The BMG bolt showed a high tensile strength of more than 1550 MPa with 1.6% plastic strain. In this study, fastening features of the BMG bolts are investigated comparing with those of conventional high tensile strength steel bolts. In addition, bolt loosening test were conducted by using newly developed test equipment which comply with Junker's test machine. The test parameters are initial clamping force and amplitude of oscillation applied to the direction perpendicular to bolt axis. The results reveal that BMG bolt maintains the clamping force at the larger oscillation amplitude with smaller initial clamping force than high tensile strength steel bolts.

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If aluminum alloy bolts and titanium bolts were tightened with the nut made of the same material, their frictional coefficient between thread surfaces was high, their tightening strength reduced accordingly. Hence if we can reduce the frictional coefficient between thread surfaces, the tightening strength increases. In this study, to improve the tightening strength of aluminum alloy bolt and titanium alloy bolt, tightening tests were conducted. In the tightening tests, five lubrication conditions were adopted. The results showed that the tightening strength of the aluminum alloy bolt was improved from 30% to 50%. The tightening strength of the pure titanium bolt was improved 10 %.

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The slippage on the mating threads due to the deformation (enlargement and shrink) of bolt and nut under tensile force induces the torsional moment of bolt shank. This torsional moment called thread torque causes the self-loosening in certain conditions. In the past research, only simplified axisymmetric model subjected to imaginary load distribution was considered. This study aims to clarify the effect of incomplete thread (thread run-out) of nut on the thread torque. Dilation of nut and thread torque were simulated by 3D FEM for bolt/nut assembly subjected to tensile force, and the results were compared with measurements. The results show that the incomplete thread of nut induces distribution of the load on the first thread, which affects the magnitude of the thread torque generated.

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It is very important for bolted joints to control the clamp force. In the practical applications, torque control method is generally used as the tightening method for the bolted joints. However, in torque control method the clamp force is affected by coefficients of friction of between bearing surfaces and between mating threads. Therefore, the preliminary tightening experiment is necessary to obtain the clamp force with sufficient accuracy. This study aims to develop the tightening testing machine which can be applicable to wide ranges of fasteners with sufficient accuracy specified in ISO16047. It had been confirmed that the target accuracy could be cleared by using piezoelectric sensors as torque cells. In this report, the structure of testing machine with adapters is analyzed be FEM to improve the accuracy and the applicability. For this purpose, the stress distribution on the sensor surface and the deformation of the structure were analyzed, and the criteria to decide parameters have been obtained.

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Tensile strength of bolt or screw is usually obtained directly by the tensile test. However, for bolt or screw with short length, tensile test is not always feasible. In such a case, torsional test specified in ISO898-7 is applied, in which the breaking torque calculated from the tensile strength and the strength ratio is evaluated. In this study, torsional rupture test on M8 bolts and FE analysis were done to find out the influence caused by free-threaded length and thread lead angle of bolt on the breaking torque. Discussion includes the equivalent diameter which used in the calculation for the polar modulus of section. It was clarified that the screw lead had a significant effect on the breaking torque, and it was advised that the equivalent diameter should be evaluated taking into account this effect.

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To prevent the wheel separation accidents, clarifying the influence of running condition on load of wheel bolts. In this paper, I investigated the stress of wheel bolts while the vehicle is moving. In the results, I confirmed that stress amplitude on left rear wheel bolts increased in the car trun to the right. Then the load of wheel bolts changed the pulsating bending load from the reversed bending load with loosing the wheel bolt.

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It is important to analyze the true causes and take appropriate measures for preventing accidents and failures which may occur world wide. In the assessment process, it is necessary to survey literatures concerning the accidents and failures and pick up the information which is used for failure analysis. It is, however, difficult to carry out the process appropriately for the engineers who don't have special knowledge in the field concerned. The aim of this study is to develop the fault diagnosis database using Hierarchical Fault Classification Method to share the specialized and customized knowledge with the engineers on the Internet. In this paper, standardization of fault description is discussed to manage common data among machine elements and an example of the system is presented.

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In order to examine low cycle fatigue life of a die used for component rolling of lag screw bolt, stress analysis was conducted by three-dimensional elastic-plastic analysis software FORGE. The form rolling simulation carried out with two dies arrangement, and performed it by the position control which fixed a principal axis interval. As a result of stress analysis, the position which the maximum of major principal stress in a dice generates was corresponded well with the position which the fatigue crack actually occurred. When analyzed by changing dice rotating speed with 10, 30 and 60r/min, the maximum of major principal stress became small in the case of 30r/min. This cause is presumed for tangential force of the dice to increase by reduction of the oil film effect due to generation of heat, while deformation resistance of a material becomes small so that rotating speed increases.

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Yoshimoto had been presented a hypothesis concerning the fatigue strength of a bolt in bolt/nut assembly based on Ishibashi's hypothesis on the relationship between the fatigue notch factor and the local stress distribution. By using Yoshimoto's hypothesis, the fatigue behavior of bolt in bolt/nut assembly taking into account the effect of the axial residual stress at the first thread root of a bolt can be explained. However, this has not yet been verified quantitatively since the local stress and the axial residual stress which may exist locally around the thread root can neither be measured nor estimated with sufficient accuracy. This study aims to quantify the relationship between the axial residual stress and the fatigue strength. In this report, 3-D elastic-plastic FE simulation was performed to calculate the axial residual stress distribution by using precisely determined material property and the interim FE model through the thread rolling process of the leadless SG (thread rolled after heat treated) bolt specimen. Calculated result shows that the axial compressive residual stress about 940 MPa level is generated at the thread root of the depth ε_0=30μm of leadless SG bolt. The difference of fatigue strength of SV (heat treated before thread rolled) bolt and SG leadless bolt assembled with threaded adapter can be explained by using the residual stress estimated.

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This study aims to clarify the effect of incomplete thread of nut on the local stress acting on a bolt thread root which may affect the fatigue strength of a bolt. First, 3-D FE analysis was performed for bolts with single-start thread and with two-start thread to examine the effect of incomplete thread on the local load shared by each thread. Considering the results obtained by 3-D FE analysis, 2-D FE analysis for two types of first thread are performed to obtain local stress distribution on a thread root. The fatigue strengths for two types of bolt were calculated using the local stress and the fatigue strength of the material. Finally, it was clarified that the effect of incomplete thread of nut could not be taken into account by 2-D FE model with constant thickness of first thread. However, Local stress changes by thickness of incomplete thread.

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Most studies of bolted joint fatigue have been conducted for a bolted joint subjected to only axial vibration or only transverse vibration. However it is considered that the actual bolted joints are subjected to multi-axial vibration. Bolted joint fatigue under multi-axial vibration, axial vibration and transverse vibration, has been investigated in this study. In the experiments, the two types of vibrations were applied to the bolted joint with same phase and with different phase. The results said that even if the bolted joint was subjected to multi-axial vibration, the fatigue strength was the same as the uni-axial fatigue strength. However the apparent fatigue limits were different according to the vibration conditions.

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Pressure vessel such as compressor and pump operated in various plants is demanded to be tightened by bolt with high axial tension, and bolt tensioner is frequently adopted for the tightening. Bolt tensioner is able to load high axial tension to the bolt by hydraulic pressure, and axial tension variation caused by contact friction among tightening parts is small. However, initial tension loaded by hydraulic pressure decreases, because of stiffness changing and transferring of tightening parts after nut seating and unloading. The ratio of residual axial tension to initial tension is the most important factor to load with high accuracy by bolt tensioner. In this study, estimating equation of the ratio was formulated by considering plastic deformation of tightening parts and re-loading of hydraulic pressure. Compliance of tightened parts is derived from elastic analysis, and plastic deformation value is derived from elastic-plastic analysis. Finally, bolt tightening with bolt tensioner was experimented, and estimation accuracy of the estimating equation is examined.

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There have been a number of issues concerning the sliding characteristics of oil-impregnated sintered bearings caused at the temperature below freezing. However, the relationship between bearing design parameters and tribological characteristics below freezing has not been clarified yet. In this study, we experimentally investigated the coefficient of friction and separation degree between the oil-impregnated sintered bearing and the journal operating at below-freezing temperature. The experimental results show that unlike the case in the range of a higher temperature than the room temperature, the temperature below freezing conditions yields a higher coefficient of friction μ and a lower separation degree τ at start of operation than those under steady-state condition. The differences in μ and τ between those at start of operation and under steady-state condition are more marked for a higher permeability of the porous matrix.

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Occurrence of cavitation in hydrodynamic bearings has been one of the most famous subjects, and there are a lot of papers on the condition of cavitation occurrence especially for plane journal bearings. With the development of surface texturing technology, more interests in the conditions of cavitation occurrence in the textured area has been taken again, especially for the case that the negative pressure area was fully surrounded by the operating fluid in the textured bearings. However, it is still unclear how much the negative pressure is needed for cavitation occurrence in the textured bearings and how much the pressure value in the cavitation area is. In this study, we designed and manufactured a visualization equipment consisting of a herringbone-grooved hydrodynamic bearing and observed the cavitation length and measured the pressure value in the cavitation area depending on the rotational speed. We used three kinds of lubricants, hexadecane, tetradecane and dodecane, as the operating fluids. The main experimental results are that: (1) for the occurrence of cavitation in the bearing clearance, negative pressure much less than the atmospeheric pressure was necessary. (2) the growth rate of the cavitation length in hexadecane became the largest because the change in solubility of air in hexadecane against rotational speed was the largest, (3) the pressure value in the cavitation area became closer to the atomospheric pressure as the length of the cavitation area was larger.

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Recent advances in smart surface engineering, coating technologies and cold spray technologies offer unique possibilities for better controlling friction and wear under lubricated rolling, sliding or rotating contact conditions. Smart surface technologies such as laser texturing and/or dimpling, laser glazing, reactive ion etching and shot-peening have also become very popular. Recently, a novel method for depositing ceramic thick films by aerosol deposition (AD) has been developed. Submicron ceramics powders are accelerated by fast gas flow and then impacted on a substrate, to form a dense, uniform and hard ceramic layer at room temperature. In this study, in order to create the textured surface without the thermal effect, AD method was employed. The conditions to deposit alumina films and the adhesive strength of the films were investigated. The thickness of deposited alumina film increased exponentially, as the reciprocating cycles increased in numbers. The deposited films were scratched using a diamond indenter. The reciprocating cycles in depositing exceed 20, the adhesive strength of the films increased from 75N to 90N.

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The heat curing oil film method using thermosetting property oil film is a new oil film method. The heat curing oil film method, in which not only the plane flow pattern in wall surface but also oil film thickness of the steady flow can be measured, is newly developed. The heat curing oil film method is a very useful method for visualization of an air flow in the clearance of an externally pressurized gas-lubricated circular thrust bearing with a central supply hole. The effect of oil component on the rheological characteristics of the heat curing oil without hardener is investigated in this paper.

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A Simiultanous analysis for piston pin bearing, connecting rod small end bearing, connecting rod large end bearing and main bearing of engine bearings is establised, by considering piston pin offset, i.e. eccentricity of center lines between pinton pin bearing bush and piston.

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In this paper, the boudary is caluculated by applying finite difference method to finite width bearing theory under Reynolds boudary condition. A negative film pressure is calculated in finite width bearing analysis, though no negative pressure in infinite width bearing theory.

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