The characteristics of an area-type shear difference method for photoelastic stress analysis were investigated. The method used an approximate equation of a directly integrated stress-equation of equilibrium between two points in any direction. The equation of sums of normal stresses induced from the approximate equation etc. was applied to any set of two points (nodes) in the region to analyze the stresses. The sums of stresses were obtained by solving the simultaneous equations for the sums of stresses, and the stress components were then obtained. Photoelastic data (principal stress differences and principal stress directions) were used in the simultaneous equations. The method was applied to a circular disk subjected to diametral compression and the effects of point-like noise in photoelastic data on the stress components of the disk were investigated. Results indicated that the stress components obtained by the method were largely unaffected by the noise.

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The stress and temperature of ultraviolet (UV) curable resin during curing were measured using a simultaneous measurement system of stress and temperature and their relationship was investigated. The specimen consisted of a mold and UV-curable rein in liquid form. The mold consisted of glass plates, acryl plates and a potassium bromide (KBr) plate. The specimen was illuminated with UV rays downwards from the upper side of the specimen. The stress and temperature were measured using a photoelastic and thermographic techniques, respectively. Results indicated the stress and temperature during curing were closely related.

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In-plane thermal strain on electronic packages is measured using digital image correlation method. A slice of an electronic package including layers of copper, solder and aluminum is used for the specimen. A random pattern for tracking the surface is made using boron nitride powder as a white color and magnetic powder as a black color. A telecentric lens is used for image capturing without an effect of the out-of-plane displacement of the specimen surface. The specimen is heated up to 180℃ from 30℃. Then, the in-plane thermal deformation of the specimen is measured. As a result, two dimensional displacement distributions are obtained. Strain distributions of horizontal component, ε_x, vertical component, ε_y and shear component, γ_<xy> are obtained from gradients of a plane approximation of displacement data in local areas around focus points. In ε_x and ε_y maps, a difference of strain values in each materials corresponding to a difference of each thermal expansion coefficient are observed. In γ_<xy> map, a shear stress concentration in the solder layer is observed. Therefore, in-plane thermal strain measurement on electronic packages using digital image correlation is possible.

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In this paper, a method for evaluating the J-integral for the displacement field obtained by digital image correlation without modeling the stress strain relationship is proposed. First, the displacement gradient and strain are determined from the displacements using a local least-squares method on the domain of integration, Next, the stress components are determined from the strain using the Hencky's equation and material properties. Finally, the J-integral value is determined by the numerical integration on the domain of integration. The usefulness of this evaluation method is verified by applying this method to the displacement field obtained from the elastic-plastic finite element analysis and digital image correlation.

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The deformations of orthodontic brackets subjected to torques were investigated using a three-dimensional digital image correlation technique. Ceramic, stainless-steel and polycarbonate brackets were used. Torques acted on the brackets through an archwire. Results indicated that the tendencies of deformation of the brackets were similar, and the amounts of deformation and slot opening of the brackets were greatly depended on the material used for the brackets. The amounts of deformation and slot opening of the polycarbonate bracket were about 6 and 21 times those of the stainless steel and ceramic brackets, respectively.

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In this study, the effect of ultrasonic shot peening (USP) treatment on the fatigue strength of stainless cast steel SCS6 for hydraulic turbine runner was investigated carrying out plane bending fatigue tests for USP treated material and untreated material. According to the fatigue test results, it was clear that the fatigue strength of SCS6 was improved by USP treatment, especially, the fatigue limit was 60 % improved. The reasons of the fatigue strength enhancement are thought to be the effects of high hardness and compressive residual stress generated by USP treatment. In addition, the effectiveness of USP treatment on the fatigue strength of SCS6 having the fatigue crack was also examined, The specimen was made by performing USP treatment after creating the fatigue crack of about 1 mm by using the plane bending fatigue test machine. The results of the fatigue tests indicated that USP treatment delayed the fatigue crack propagation compared with the case of USP untreated, The main reason of above results was that the fatigue crack propagation resistance was increased by the compressive residual stress generated by USP treatment, in other words, the stress intensity factor K was decreased by that factor. According to these results, it can be said that USP treatment is very effective method to improve the fatigue strength of SCS6.

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Rotary bending fatigue tests using double ultrasonic shot-peened (USPed) magnesium alloy AZ61 were performed to investigate the effect of double ultrasonic shot peening (USP) on fatigue behavior. Double USPed specimens were USPed under the condition of the shot diameter, φ1.0mm and the coverage, 300%, and then USPed under the condition of the shot diameter, φ0.6mm and the coverage, 300%. The fatigue strength of double USPed specimen was highly improved compared with not only the base metal but also the single USPed specimens under the same condition of the first and the second USP of the double USP. It is considered that the improvement of fatigue strength of double USPed specimen is attributed to the enough increase in hardness and compressive residual stress in the first treatment and the decrease of surface roughness in the second treatment.

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Recently, high temperatures gases are used to make gas turbines more effective. Ceramic spraying is an effective technique used to protect component material against the attack of such gases. However, cracks and delimitation can occur in the ceramic coat because of a difference in mechanical property. These cracks and delimitation become a serious problem since they reduced the strength of material. In our research we conducted a fatigue test at high temperature to find the best thermal spraying conditions.

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In this study, in order to investigate the effect of the Cr diffusion layer and the Diamond Like Carbon (DLC) film on fatigue properties of the carbon steel S45C.Firstly, Cr diffusion layer was formed on S45C. Secondly, DLC film was covered with S45C. However, the materials were heated to a high temperature during forming Cr diffusion layer. Therefore, the material only performed by heat treatment was prepared as compared materials. The fatigue test results showed that the fatigue strength of DLC materials with Cr diffusion layer was higher than that of heat treated materials. In order to examine the reason for that result, the fatigue crack propagation was observed by means of plastic replicas. According to this measurement, it was found that fatigue crack initiation life of DLC materials was longer than that of heat treated materials. Therefore, it was cleared that DLC film increased the fatigue crack resistance of S45C.

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In order to investigate the effects of a new surface modificadon method "the substrate quenching after coating" on the rolling contact fatigue strength, TiN coated steel specimens and CrAlN coated steel specimens were processed by this method and the thrust type rolling contact fatigue tests were carried out for these specimens. In the process of the substrate quenching after coating, two types of quenching methods, furnace quenching and laser quenching were used For the furnace quenched specimens, the delamination initiation life of CrAlN coated specimen was longer than that of TiN coated specimen. This reason could be explained by the difference of the oxidization of CrAlN and TiN in their furnace quenching process. For CrAlN coated specimens, the delamination initiation life of the laser quenched specimens was longer than that of the furnace quenched specimens. After the initiation, the delamination of the furnace quenched specimen grew much faster than that of laser quenched specimen. These reasons could be explained by the difference of the process time of the furnace quenching and the laser quenching. The process time, in which the ceramic coating of the specimen was exposed to an elevated temperature, of the furnace quenching was much longer than that of laser quenching. It is considered that substrate laser quenching after coating could be an effective way to improve the delamination initiation life and to reduce the delamination growth rate under rolling contact fatigue.

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The purpose of this study is to investigate the influence of microstructure on strength properties of Al-Mg-Zn series alloy under corrosive environment. Zn was added to Al-Mg alloy of AC7A, to improve its mechanical properties. In this study, weight fraction of Zn addition was controlled to 3.1, 3.4 and 4.1 wt%. Appropriate conditions of solution treatment and aging (T6) treatment were conducted to equate its strength with that of AC4CH which is the conditional material of aluminum wheel. The heat treated material was machined to tensile specimen with circumferential V-notch. Tensile strength under corrosive environment was characterized by constant load tensile test with 1wt% of NaCl solution of corrosive media. Behavior of hydrogen generation was evaluated by fixed point observation. Test results were as follows; tensile strength decreased under corrosive environment and the amount of hydrogen generation was increased with increase of weight fraction of Zn. Microstructure observation showed that Mg and Zn were segregated around grain boundary and fracture surface was selectivity formed around segregation.

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Sub-surface fractures are known as a characteristic fatigue mode of high strength steel in very high cycle region. To reveal the mechanism of sub-surface fractures, ΔK-decreasing tests were conducted in high vacuum and air environments based on the idea that sub-surface cracks are exposed to vacuum-like environment. As a result, fatigue crack growth rates in high vacuum were slower than those in air. In high vacuum, fatigue crack growth still took place at a considerably low rate around 10^<-13> m/cycle, and the threshold stress intensity factor rage (ΔK_<th>) in high vacuum was smaller than that in air, Unlike in air environment, negligible effects of oxide-induced crack closure in vacuum was considered as the reason for the results. The behavior of fatigue crack growth properties in high vacuum well explained the characteristics of sub-surface crack growths in very high cycle regime.

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Fretting fatigue is one of the major factors in the design of hydrogen equipment. The effects of internal hydrogen and environmental hydrogen on the fretting fatigue strength of SUS316 and SUS304 austenitic stainless steels were studied. The internal hydrogen reduced the fretting fatigue strength of both materials. The reduction in the fretting fatigue strength became more significant with increase in the hydrogen content. In this study, fretting creates local adhesion between contacting surfaces. It can be presumed that severe plastic deformation and microstructure change at the adhered spot enhances the effect of hydrogen. The one of the reasons for this reduction in fretting fatigue strength is hat internal hydrogen assists fretting fatigue crack initiation. When the fretting fatigue test of the hydrogen-charged material was carried out in hydrogen gas, the fretting fatigue strength was the lowest in this study. Internal hydrogen and environmental hydrogen synergistically worked to reduce the fretting fatigue strength of the austenitic stainless steels.

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Stellite alloys have excellent erosion resistance and are used for valves as weld overlays. It is important to fabricate the weld overlays in our laboratory for better understanding. Stellite has a problem that radiation quantity increases in the plant, when the stellite is exposed to radiation. Therefore, Co-free alloy is desired as an alternative erosion resistant material. In our laboratory, we found that Ti-Ni shape memory alloys (Ti-Ni SMAs) have an excellent erosion resistance. We examined the Ti-Ni alloys as a surface coating. In this study, cavitation erosion tests were carried out by using weld overlays of stellite alloys and Ti-Ni alloys which were made with our weld overlay apparatus. The results showed that the erosion resistances of weld overlays of ST6 and ST21 are about 12-15 times higher than that of SUS304, thus weld overlays of stellite alloys show excellent erosion resistances. Moreover, we found that the erosion resistances of weld overlays of Ti-Ni alloys are about 2-14 times higher than that of SUS304, thus the erosion resistances of weld overlays of Ti-Ni alloys are the same or higher than that of stellite alloys. By using arc melting furnace, the erosion resistance of the arc melting alloys were compared with that of weld overlay.

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Fatigue properties of shot-peened high strength Al-Cu-Mg alloys, extruded and drawn 2017-T4, and effect of humidity on the properties were investigated in relative humidity of 25% and 85% under rotating bending. Fatigue strength was increased by shot-peening irrespective of humidity. Although fatigue strength was largely decreased by high humidity in the electro-polished specimen, there is no or little influence of humidity on fatigue strength in the shot-peened one. In the electro-polished specimen of the extruded alloy, the crack propagation changed from a shear mode to a tensile one with decreasing in stress level in high humidity, while the propagation in the shot-peened one was in a tensile mode in both humidity environments similar to the one in the electro-polished specimen in low humidity. Most of fracture surface in low humidity was occupied by striations in both specimens. On the other hand, those in high humidity were covered with slip planes in the shear mode crack, and with a few brittle facets in the extruded alloy or brittle striations in the drawn one in addition to striations in the tensile one irrespective of shot peening.

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The fracture toughness, J_<Ic>, of SCM435 was investigated in 115 MPa hydrogen gas, 0.7 MPa hydrogen gas and air at room temperature. J_<Ic>ig tests were conducted in accordance with the ASTM E1820. J_<Ic>ig in 115 MPa hydrogen gas was much smaller than in 0.7 MPa hydrogen gas and air. In air, a stretched zone was formed at the tip of the fatigue pre-crack, followed by dimples. In hydrogen gas, quasi-cleavage instead of stretched zone and dimples were formed at the pre-crack tip. The fracture toughness test shown in 0.7 MPa hydrogen gas is the same as that shown in a fatigue crack growth test in 0.7 MPa hydrogen gas at a number of cycles of n = 1 and stress ratio of R = 0; and thus J_<Ic>ig in hydrogen gas is not the real fracture toughness.

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In order to investigate the fatigue characteristics of A2024/A6061 Aluminum alloys dissimilar friction stir welded joints, A2024 and A6061 plates were joined with the welding speed of 6lmmimin and the rotating speed of tool of 1400rpm. Fatigue tests were conducted at stress ratio R=-1, cyclic speed 23.3 Hz with plane bending fatigue condition. Fatigue strength of FSW joints were similar to A6061 base metal, but in the high stress region, fatigue life of FSW joints were shorter life than one of A6061 base metal. Crack growth rate of FSW joints were faster than parent metal and many crack were generated in the FSW joints in high stress region. Fracture position of FSW joints were shifted about 3mm to 5mm A6061 side from weld center. Weld zone of FSW joints were softening due to temperature rise during the FSW process. Hardness of weakest point of FSW joints were about 61HV. Fracture position and Vickers hardness decline position corresponds well.

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To obtain the fatigue properties at stress concentration region of Ni-based single crystal superalloy at high temperature, the fatigue tests of notched round bar specimens with notch radii of R0.35mm and R0.06mm were conducted at 650℃. Then the fatigue life of notched round bar specimen with notch radius of R0.1mm was predicted using the theory of critical distance. The calibration method was employed to determine the critical distance. In this study, as the calibration method the stress distributions in the vicinity of the notch tips obtained from FE-analysis for each notched specimens were used. And the critical distance stress was determined as the averaged stress from the notch tip to the critical distance. Then the relationship of the critical distance stress and the fatigue life, which is independent of notch sizes, was obtained. This relationship was used to predict the fatigue life of notched round bar specimen with notch radius of R0.1mm. The predicted life relatively agreed with the experimental one. And the scattering was within a factor of two.

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Joint microstructures and fatigue behavior of ferritic stainless steel type 430 welds with different weld metals were investigated. Two weld metals with different chemical compositions, NbL1 and NbL2, had been used for the MIG butt welding of type 430. NbL2 with Al and Ti showed fmer grains in the weld microstructure than NbL1. In both NbL1 and NbL2 welds, the hardness of heat affected zone (HAZ) was the highest due to the formation of hard martensite. Fully reversed axial fatigue tests have been performed using smooth specimens of welds and base metal at ambient temperature in laboratory air. The fatigue strengths of both welds were increased compared with the base metal, which could be attributed to the increase of hardness in weld zone. The fatigue strengths of NbL1 and NbL2 welds were nearly the same.

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Dental resin composite is widely used in recent years because of its excellent aesthetic and operability. However, the fatigue strength of composite resin is not clear until now. Therefore, this study investigated the improvement in strength by means of filler hybrid using several types of fillers. Especially, we studied on how to improve the tensile fatigue strength of hybrid-type composite resin.

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Equations expressing fatigue strength diagrams of notched materials have to explain both of material dependence and notch size dependence of notch effects. From such a viewpoint, two concepts have been introduced into the study. The first is the hypothesis of cyclic plastic adaptation that reflects mechanical behavior/property peculiar to persistent slip bands and the parameter of an equivalent cyclic stress ratio that is derived from the hypothesis and can correlate the fatigue strength diagrams of the notches of a large size very satisfactorily. The second idea is the inclusion of some notch size factors in the equation of the fatigue strength diagram in order to take a size effect into consideration. The concrete forms of these size factors are determined based on the distribution of the fatigue strength σ_<w1> and σ_<w2> that are drawn on the notch behavior map. At the beginning, the notch size factors are determined by trial and error, empirically rather than analytically, though they are done based on a systematic way to some extent. However, the subsequent research has proved that the notch size factors can be determined directly as numerical expressions based on a notch root yield zone model, which is extended from Dugdale Model. In the present paper, the process of determination of the notch size factors is described as a main subject.

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This paper studies deformation of CFRP at microscopic area and observing technique. Tensile test is carried out for CFRP specimen and digital image correlation (DIC) method is used to observe deformation of microscopic area, especially around its fiber interface. CFRP specimen is loaded by tensile testing machine for investigating deformation around vertical section of fiber. Diameter of carbon fiber used which is mainly interested in the specimen is micro scale, therefore scanning electron microscope (SEM) is used to gain high magnification and resolution pictures as they deforms. To achieve this in-situ experiment, testing machine which can be used in SEM is developed. The essential to achieve DIC is selection of random pattern used to follow up change of the area, which greatly influences accuracy of result. Colloidal silica and the other particles are utilized for random pattern with adjustment of concentration. The pattern must be seen clearly and small enough compared to fiber vertical section. Through this research, examination of deformation observation at microscopic area and consideration of fracturing procedure of CFRP are performed.

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In this study, we research the mechanical properties of Capsule-Chuck which is a product to hold and turn a roll's core. Capsule-Chuck holds roll's core by swelling urethane loading Air pressure. We want to research the performance characteristic of Capsule-Chuck. When the roll's core contacts fixed parts of the capsule by increasing of load, dust is generated and the rolls of products are damaged. In this study, we research the load limits of rotating Capsule-Chuck by using the new experimental device and compare with the load limits of non-rotating.

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We present theoretical and experimental results on the fracture behavior of single-edge precracked giant magnetostrictive materials under magnetic fields. The crack was created normal to the direction of easy magnetization. Three-point bending fracture tests were carried out, and the fracture loads were measured. Plane strain finite element analysis was also performed, and the energy release rate was calculated. The effect of magnetic field on the energy release rate and apparent fracture toughness (critical energy release rate obtained using the fracture load) was then discussed.

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Recently, adhesive bonding has been used in functional composite structures. Purpose of this study is to clarify the characteristics of bending strength for adhesively single-lap joints with both adherends, "unidirectional CFRP laminates" and "metal materials". We analyzed four types of adhesively single-lap joints subjected to 3-point bending moment by Finite Element Method. In addition, failure loads of various adhesive joint specimens were measured. By comparing the results of four different types of joints, we obtained conclusions as follow. Under all joint combinations, each stress component and maximum principal stress distribution at adhesive layer were singular behavior, and indicated maximum stress value at edge in longitudinal direction. Maximum stress value at adhesive layer using SS400 as material of one side adherend proved to be the lowest in the four kinds of joint combination. From the experimental results, it was found that bending strength increase as Young's modulus of lower side adherend decrease.

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The purpose of this study is to investigate the snap-through phenomenon of catheter made of soft nylon resin and is reinforced with thin stainless wires. The buckling behavior under initial torsion has been examined by using short specimens due to perform more accurate measurement. As a consequence, the influence of stress relaxation on the buckling behavior has been made clear in a series of our previous reports. However, in the actual usage, there is a possibility that the snap-through phenomenon occurs when the relatively long specimens are used. So, in this study, the snap-through behavior of catheter under initial torsion is examined. In particular, the experiments, using the test pieces impregnated with water, are carried out by changing the angle of the initial torsion, the length of specimens and axial displacement speed variously. Then, the occurrence regions of the snap-through behavior of the hydrous and the non hydrous catheters are investigated and discussed in this paper.

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In this study, a 3D printer enabling a reinforced-printing with wires is proposed. Maximum bending stress of a test sample with wire improved more than 20.1% compared with a test sample without wire. Bend-elastic-constant of a test sample with wire improved more than 19.8% compared with test sample without wire.

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We fabricated dispersed C_<60> molecules/A1 nano-composite thin films using by a conventional vacuum evaporation method. The microstructural characterization of the films obtained clarified the uniform dispersion of C_<60> molecules in Al based film. Nano-indentation hardness of Al-1.0 wt.% C_<60> film showed increase up to 3 times larger than that of Al film. These results clearly indicated that dispersion of C_<60> molecules in the conventional films contributes to drastic improvement in mechanical properties. In this study, we focused on conventional high hardness TiN films fabricated using by RF magnetron sputtering method. For the purpose of evaporating C_<60> molecules, the heating evaporator was equipped directly below the substrate of existing RF magnetron sputtering chamber due to prevent from the influence of plasma. It was possible to control the deposition rates of two kinds of evaporation sources to become the predetermined compositions separately. C_<60>/TiN films with constant thickness of 100 nm were deposited on Si(100) water-cooled substrates using by the RF magnetron sputtering deposition method for 30 minutes. X-ray diffraction showed TiN crystalline structure, and FT-IR analysis clarified the existence of C_<60> molecules contained in TiN films for all composite films. Nano-indentation studies showed that the hardness of the composite film of TiN-2.0 wt.% C_<60> showed the maximum hardness of 18 GPa and this value was increased up to 30 % larger than that of TiN film.

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In this study, tensile strength and fracture toughness of plant-short-fiber reinforced PLA (poly (lactic acid)) were experimentally evaluated. Interfacial shear strength between the plant fibers and the matrix resin was also obtained by means of the microbond test. Kenaf bast fibers were used as one of the typical plant fibers and surface treatments (alkali and silane-coupling agent treatments) were also performed to the fibers. It was found that, in general, these surface treatments made interfacial shear strength, tensile strength and fracture toughness of the present kenaf/PLA composites improve as compared to those of untreated fibers.

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The present study investigated crack visualization in metallic structures using time-domain reflectometry (TDR) with differential circuit of microstrip line (MSL). It was problematic that single ended of two-dimensional (2D) MSL was affected by the cross talk voltage because of the interference of adjacent MSL. Differential circuit enables to suppress the cross talk voltage by taking the difference. Crack visualization experiments were conducted using the proposed TDR with differential circuit of 2D MSL for different crack lengths. The experimental results demonstrated that crack propagation could be clearly visualized by determining the appropriate threshold. To observe the time change of the electric field, the electromagnetic fields of the differential circuit was numerically simulated using the finite-difference time-domain method. The simulation results clarified that the cross talk voltage decreased, because the electric field of the differential circuit caused by interference of adjacent MSL was in phase. It agreed with the experimental results.

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A single roll caster equipped with a scraper was proposed, designed and assembled. Properties of this caster and of the strip cast by this caster were investigated. 5182 aluminum alloy was cast into the strip. This caster could cast the strip at the speeds ranging from 20m/min to 40m/min. Strip thickness could be controlled by the roll speed and the solidification length. The as-cast strip was free from center-segregation and inside-micro-porosity. The as-cast strip could be cold rolled down to 1mm. There was no difference between the roll contact surface and scribed surface of the cold rolled strip. The mechanical property of the strip cast by this caster was as almost same as the strip made by D.C. casting and hot rolling process.

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Short alumina fiber-reinforced aluminum alloy composites were fabricated by squeeze casting, and the effects of the fiber reinforcement on the machinability of the alloy under various cutting conditions were investigated. JIS-AC8A alloy was used as the matrix metal, and two kinds of short alumina fibers were used as the reinforcements. The cutting force of the alloy was reduced by the fiber reinforcement. The lower the hardness of the fiber in the composite, the lower the cutting force of the composite. The roughness of the machined surface decreased by the fiber reinforcement under every cutting condition, and the roughness of the composites was close to the theoretical roughness. This result and in-situ observation of cutting process indicate that the fibers in the composite suppress the formation of the built-up edge during the cutting process. The machined surfaces and chip forms indicated that the fibers in the composite facilitated the shear deformation of the chips because the fibers were easily sheared by the cutting.

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Ti-29Nb-l3Ta-4.6Zr alloy (TNTZ) is expected to be used as biomedical applications such as a spinal fixation device. For a practical application, high durability of the spinal fixation device is required in order to ensure mechanical safety. The durability of the spinal fixation device with a rod made of TNTZ subjected to a surface hardening treatment was investigated in this study. The rod was prepared through a levitation melting, a hot-forging at 1273K, a solution treatment at 1063K for 3.6 ks subsequently water quenching, machining and finally a cavitation peening (CP) treatment for surface hardening (TNTZ-CP rod). Microstructure was observed using transmission electron microscopy (TEM). The durability was evaluated by compressive fatigue test applied to the spinal fixation device. Nano-scale graines were observed at the surface of the TNTZ-CP rod. The nanocrystalization was caused by the CP treatment. The compressive fatigue strength of the spinal fixation device with the TNTZ-CP rod was higher than that of spinal fixation device with a non-CP treated TNTZ rod.

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Adding grain refiners as nucleants is the most common method of refining the grain structure of aluminum casts during the solidification processes. Improvement of grain refining performance can be achieved by severe plastic deformation of grain refiners, since density of heterogeneous nucleation sites could be increased. Another method is use of heterogeneous nucleation sites with smaller disregistry value. In this study, novel refiners for Al cast containing Al_5CuTi_2 intermetallic compound particles with Ll_2 structure or spherical shaped Al_3Ti intermetallic compound particles with DO_<22> structure are fabricated by spark plasma sintering method. The grain refining performance of fabricated refiner was tested using addition of the refiner of 1.2g into molten pure Al of 148.8g. By using the novel refiners, it is found that the grains of Al cast are refined. In this way, these intermetallic compound particles with smaller disregistry value can become favorable heterogeneous nucleation sites for Al cast. Using heterogeneous nucleation sites with lower disregistry value, therefore, one can obtain finer grained Al cast with higher mechanical properties.

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Amorphous carbon (α-C:H) films have high chemical resistance. To determine etching rates on such film, the detection of nanometer thickness change is required. In this study, etching rate on α-C:H films by nitric acid was evaluated using surface plasmon resonance (SPR) device with a multilayer structure consisting of an α-C:H layer on metal. A flow cell was used to introduce the nitric acid onto the α-C:H top layer of the multilayer structure. Nitric acid solutions were injected into the flow cell. The SPR angles were determined as the angle with minimum reflectivity. SPR angle decreased as the time elapses. From the behavior of the SPR angle, the α-C:H film surface was etched by nitric acid. An etching rate of 0.75 nm/h was obtained in the case of using 0.3 mol/l nitric acid. This result indicates that the evaluation using the SPR device with a multilayer structure can be used to detect the extremely slow etching in a liquid.

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This paper describes the elucidation about the etching operation of electrolyzed oxidizing water (It abbreviates as EO water) on copper nickel alloy for lead frame. First, the etching characteristics of EO water against the surface of copper nickel alloy for lead frame was clarified using chemicals for comparative immersion experiments. The comparative study showed that as for the etching efficiency on copper iron alloy, Na_2SO_4 EO water was superior to H_2SO_4 solution, and NaCl EO water was superior to HCl solution. Next, EO water has the selective etching tendency to Cu element in copper nickel alloy for lead frame like chemicals. As for the relationship between immersion time and etching depth, Na_2SO_4 EO water is same as NaCl EO water, and become proportional connection.

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In order to improve the corrosion resistance properties of structural steel (SS400) for bridge construction in corrosive environments, coatings of Al-Mg mixtures were deposited to protect SS400 substrates. This study observes the in-situ observation of cracks and focuses on the interfacial crack initiation and the corrosion fatigue crack behavior of the Al-Mg coating layers deposited on SS400 with different Mg concentrations. The investigation was carried out by using the four point bending (4PB) test in order to detect the interfacial strength between coatings and substrates of Al-Mg mixtures. Acoustic emission (AE) signals during the entire 4PB test were also measured in order to monitor the crack initiation and crack propagations and were analyzed by fast Fourier transform (FFT). The interfacial strength of Al-Mg coated SS400 decreases after immersion in NaCl aq.. There was little change in the interfacial strength of the Al-Mg coatings by different Mg concentrations in the ranges of present study.

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The important factors to produce the iron rust are oxygen, existence of electrolyte such as water and the hydrogen ion. Experiments have been carried out to prevent iron rust in water flow by developing the ion balls having the structure of polar crystal metals. Ion balls make it possible to emit e ion particles because they are composed of the polar crystal metals. The water temperature and water flow speed are around 25℃ and 10 cm/s, respectively. The diameter of ion ball is approximately 7.30 mm. The results obtained show that e- ion particles emitting from ion balls in water flow bring to change pH in the range of around 7.2 to 8.2 and e- ion particles may react with FeO(OH) produced during the rust generation process, and then the black rust (Fe_3O_4) as passive state film of 0.1 μm to 100 μm in thickness is generated in iron surface. This fact shows that the ion balls developed in the study makes it possible to restrain the progress of red rust at iron surface.

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The formation of an Fe-Al intermetallic compound film on lightweight metals by shot lining and heat treatment was investigated. In the experiment, a centrifugal-type peening machine with an electrical heater was employed. The shot medium was high-carbon cast steel. The substrate was a commercial aluminium alloy and magnesium alloy. The sheet was commercially available pure aluminum, and the powder was an electrolytic iron. The shot lining process was carried out at 573 K in air using a peening machine. The top surface of the lined workpiece was melted by laser beam irradiation. The lined substrates exhibited a harder layer of aluminum-rich intermetallics in the irradiated part. It was confirmed that the present method could be used for the formation of functional films on lightweight metals.

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The effect of an intermittent microshot peening on the surface characteristics and fatigue life of spring steel SUP9 was investigated. In the experiment, the projective method of the microshot was of the compressed air type. The microshot of 0.1mm diameter was high-carbon cast steel, and the workpiece used was the commercially spring steel. The effect of the intermittent peening on the surface hardness was studied. Fatigue tests were carried out in a rotary bending fatigue test machine. The surface layer of the workpiece was sufficiently deformed by microshot peening. S-N curves were established for unpeened and peened conditions. The intermittent peening process improves the fatigue life, especially at a high number of cycles.

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Multistep V bending of SUS304 and SPC sheets were carried out. Effect of number of bending steps and first stroke on springback with changing holding time at bottom dead point was investigated. The effect of number of bending steps on springback in SPC sheets was small, but that in SUS304 sheets was large. The effect of number of bending steps on springback was larger than that of holding time at bottom dead point.

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Rotary swaging process of a tube was simulated using finite element method. The diameter of the tube was 2 mm and the thickness was 0.35 mm and the length was 10 mm. Rotation rate of the dies was 545 rpm and the feed rate was 20 mm/min. It is found that the hydrostatic stress of the workpiece at the surface became tensile state and The circumferential stress became large. The hydrostatic stressin the cross-section became also tensile state. Circumference stress and axial stress were also large.

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This paper describes for a pushing-cut process of stacked multiple pieces of cardboard. The profile quality of wedged cardboards is empirically affected by the stacked structure and numbers of piece, the contact friction coefficient with each layer, the thickness of cardboard and blade tip profile. However, the sliding behavior of stacked cardboards is not almost discussed due to its complicated motion phenomena. In this work, therefore, the effects of mechanical conditions on the cutting characteristics of stacked postal cards of 0.22mm thickness were experimentally investigated by varying the stacked numbers of cardboard. A certain repeated force drop was observed. The dispersion of repeated force drop remarkably increased when the stacked number was larger than 7 pieces.

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Effect of tool diameter on formability in friction stir incremental forming was investigated. Formabilities were compared by forming pure titanium sheets which dimension is 100 mm x 100 mm x 0.3 mm. Tool diameters were 4, 5, 6 and 8 mm. From the experimental results, it was confirmed that as the diameter of forming tool became smaller, the formability became higher and the range of formable tool rotation rate was wider.

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A newly developed Ni base dual two-phase intermetallic alloy that has greater high-temperature strength and hardness than many conventional super alloys has been applied to FSW tools used to join mild steel plates with 1.0mm thickness. Appropriate joining conditions are evaluated by appearance of welded lines and tensile properties. The results show that the higher the tool revolution, the wider the appropriate ranges of joining speed. Furthermore, within the range of the experimental conditions, the slower the joining speed, the higher the tensile strength of the joints.

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Welding is used to many structures and is important joining method in industry. Because metal is heating locally by welding, residual tensile stresses is generated in the heat affected zone. The tensile residual stress degrades fatigue strength of component, and will be one of causes of stress corrosion cracking in SUS304. Therefore it is important to decrease the tensile residual stresses. Accordingly, we have been proposed a method that adds ultrasonic vibration during welding. It can reduce the tensile residual stresses easily in a shorter time than conventional methods in SS400. In this study, reduction of the residual stress using ultrasonic vibration was studied in examination for build-up welding of thin plate in SUS304. SUS304 can keep strength in high temperature environment. Therefore, two ultrasonic vibrations that have different frequency were added to get plastic deformations that cause reduction of the residual tensile stresses by large vibrational amplitude. It is shown that using ultrasonic vibration can reduce the residual stresses in SUS304 which have high temperature property.

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Transient shape variation of a rotating liquid droplet is simulated numerically by solving the three dimensional Navier-Stokes equations using the level set method. It is shown that the spherical droplet becomes the two-robed shape after the initial transient and the relation between the deformation and the rotation rate is in good agreement with the existing experimental results.

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A silicon oil droplet with a diameter of about 2mm dropped on a silicon oil pool was sustained for a long time period. The petri dish containing the liquid was vertically oscillated at 50Hz. The droplet kept its horizontal position on the surface of the liquid. When another vertical vibration of 500Hz is superimposed on the previous one, the droplet moved to another position and stayed there. Then, if the superimposed vibration was stopped, the droplet moved back to the original position. The droplet repeatedly moved between the two positions according to the state whether the 500Hz vibration was on or off. The two positions sensitively depended on the setup of the petri dish and the vibrator. The surface wave profile of the surface of the liquid pool was measured by a laser displacement meter. The time averaged surface profile slightly deformed from a flat plane. Several depressions were observed on the surface. However, the relations between the droplet's position and the depression's position were not obvious.

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In this paper, numerical simulation of air bubbles moving in a mini channel was performed. The velocity and size of the bubble, and the separating distance between two bubbles were investigated. The results were compared with the experimental data.

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Experimental study was carried out on the vortex breakdown phenomenon in an open cylindrical container with the rotating bottom endwall. Vortex breakdown is seen in certain parameter range of the container aspect ratio H/R and the rotating Reynolds number Re. The working fluid used water-glycerin mixture. The meridional plane of the cylinder was illuminated by fluorescein sodium which is mixed with the working fluid. Velocity map in the meridional plane was measured by using a particle image velocimetry (PIV). Various types of vortex breakdowns were observed. Comparison with the previous experimental and numerical studies is discussed in detail about position of stagnation points, bubble size and differences between present and previous results.

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