The strengthening mechanism of the glass-fiber at cryogenic temperature has not been fully studied so far. In the present study, tensile tests of a single E-glass fiber with heat treatment in air and liquid nitrogen were conducted to reveal the strengthening mechanism. The strength of glass fiber in liquid nitrogen was twice as high as the strength in air. Based on the area of the mirror zone in the fracture surface, the mirror constant was detemined. Besides, the mirror constant of the glass fiber were equal regardless of the heat treatment condition and the testing temperature. From the observation of surface crack, it was clarified that the mirror zone was the mark of surface flaw propagation and therefore it was suggested that the area of mirror zone doesn't have a direct effect on fiber strength.

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We investigated the fabrication process and the mechanical properties of the AZX912 alloy machined chips sintered with gas forming material powder, Celltetra, and then, extruded. The fabricated material became porous by foaming of Celltetra. Relative density, ρ/ρ_0, of 0.34 was obtained with the volume expansion ratio, V/V_0=4 at 963K. It was proven that Celltetra powder agglomerates and the foaming occurs at the triple junction of the magnesium alloy matrix. In compression tests at room temperature, we obtained stable plateau stress in the extrusion direction of the material at the strain rate of ε=10^0s^<-1>. Generally, it is difficult to check internal pores visually. Therefore, by using the X-ray CT equipment, detailed pore information was acquired as CT image in this study. We also observed xy-, yz-, zx- surface with optical microscope to obtain the characteristics of the material. Then, pore feature and the material characteristics were correlated analyzing the CT image with the image processing technique. It was proven that uniformity and pore shape of the inside sectional structure influenced the plateau region and plateau stress.

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The effects of the microstructure on damping capacity of magnesium alloys (AZ31B, AZ61A and AZX311) were researched. Magnesium alloys of various microstructures were changed by heat treatment and cold rolling processing. Internal friction of magnesium alloys has increased as the Vickers hardness decreases. However, it seemed that the influence of annealing and cold rolling was small to the damping characteristics on practical use. On the other hand, magnesium sheets that had been made by powder extrusion process showed good damping capacity.

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A metallic cellular material containing polymer has been fabricated by the penetrating polymer into porous metal. The epoxy resin was penetrated into the porous stainless steel and the metallic cellular materials containing polymer was then fabricated. The compressive tests were carried out to measure the mechanical properties of these materials. The results show that the strength up to 10% strain and Young's modulus of this metallic cellular material is much higher than the metallic cellular material without epoxy resin and epoxy resin.

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Recently, CO_2 emission regulation in automobile industry has been started and improvement of fuel consumption is required from the view points of global warming and energy problems. Weight reduction is one of the ways to solve these requirements. Aluminum alloy with superior strength and high specific gravity will be a candidate material for reducing the weight of automobile structural components. As automobile components, high fatigue strength and toughness as well as tensile strength are required. However, improvement of strength tends to decrease toughness. In the present study, effects of microstructure on fatigue strength and toughness of 6000 aluminum alloys have been reported.

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Internal friction i.e. damping capacity of a solid is a structural sensitive mechanical property and is often measured for the purpose of obtaining the information on the change of microstructure of the material. In this study, the effect of microscopic texture of the commercially pure aluminum on its internal friction has been investigated. The microstructure of pure aluminum was controlled with changing the heat treatment temperature. The measurement of the internal friction was conducted under various temperatures from the room temperature to 798K using an inverted torsion pendulum apparatus. It has been clarified that the annealing process changes the peaks and the backgrounds of the internal friction. These results can be interpreted by the differences in the dislocation mobility and the average grain size of the material. The peak component of the internal friction, observed only in the specimens annealed at 773K for 3.6ks, is expected to be due to the slip at the grain boundaries in viscous manner under approximately 600K.

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The interfacial strength is the most important mechanical property among those of constituents in Polymer Matrix Composite: PMC. In this study, we conducted the tensile tests on Single Fiber Composite specimen and observed initiation of interfacial debonding at different loading rates. As a result, we recognized dependency of the interfacial strength on strain rates. According to the elasto-plastic analysis assuming that matrix's yield stress varies depending on strain rates, the stress distribution of the interface becomes close to the elastic analysis and it can be concluded that the dependency of interfacial strength on strain rates is caused by matrix's dependency on strain rates.

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Bending strength test were carried out on injection-molded and transfer-molded short glass fiber reinforced phenolic resin composite. The effects of the short fiber content (V_f=0%, 20%, 50%), distribution of fiber orientation on bending strength and elastic modulus were investigated in comparison with molding processes. The bending strength and elastic modulus became higher with increasing fiber content. Increasing rate of bending strength and elastic modulus on injection-molded were higher than transfer-molded. Mechanical properties evaluation diagram was prepared to predict the bending strength and elastic modulus with modifyed rule of mixtures proposed by Fukuda and Kawata, and Fukuda and Chou. By comparing the predicted elastic modulus and bending strength with experimental results, the validity of the diagram is examined with an maximum uncertainty of 15%.

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Micro-deformation around the boundary of multi-layered steel was measured by electron moire method and using micro-grid. The femto-second laser exposure system was used to fabricate model grids for electron moire method for micro-deformation measurements. Micro-strain distribution of the laminated steel specimen during three-point bending tested was measured by electron Moire method. Strain concentration near the boundary and non-uniform strain distribution around the boundary could be observed. Micro-deformation near the boundary also could be observed using micro-grid.

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To find the anodizing condition of Mg that has film with high corrosion resistance, the current when the anodizing (60V×180s) and the immersion treatment (0V×60s) were repeated was measured. The initial current of re-anodizing of Mg in the NaOH solution was very high, and it was thought that the anodic oxide film was unstable. On the other hand, the initial current of re-anodizing in the Na_3PO_4 solution is low, and the tendency to the current change resembled the case of anodizing of Al in phosphoric acidic solution that formed the film with high corrosion resistance. Therefore, the anodic oxide film in Na_3PO_4 solution was expected to have corrosion resistance. And, it was thought that the measurement of the re-anodizing current is useful for the evaluation of the film property.

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This study focuses on grain motion in TZP (Tetragonal Zirconia Polycrystal) ceramics during superplastic deformation. The zigzag motion of grains was found in experimental data and analyzed statistically based on Brownian motion. At the beginning of deformation, constraint by surrounding grains is widely distributed, however, it becomes spatially uniform after 15% true plastic strain.

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This paper describes the search for novel Pt-free thin film amorphous alloys for use as optical glass lens molds. Two Ni-Nb-Zr thin film libraries were fabricated by a combinatorial arc plasma deposition. From the results of an X-ray diffractmetry and energy dispersive X-ray fluorescence spectrometry, the amorphous composition region was decided in the Ni-Nb-Zr system. Five Ni-Nb-Zr thin film amorphous samples that exhibited non-crystallization over 100h heating at 723K were re-fabricated using a carousel type sputtering system. The samples were evaluated in terms of various properties: mechanical properties, anti-sticking properties to molten glass, and machinability, in order to find the most suitable composition for the optical glass lens molding die. As a result, Ni_<35>Nb_<40>Zr_<25> was found to be a suitable composition for a glass lens molding die material. This sample exhibited fracture stress of 1.71GPa, excellent anti-sticking properties to molten glass, and good machinability, which was improved by modifying the fabrication method.

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The foundation is cosmetic powder compacts. An accident such as the fracture occurs, if it drops during using or carrying. In this study, the powder compact of foundation was molded under various conditions with the automatic servo press machine which we developed. Fall tests of the foundation were conducted for various times (n) from various heights (h) and then the fracture behaviors were examined. Several fracture patterns were observed such as surface crack, internal crack, flaking of surface layer and disintegration when the foundation was subjected to relatively high impact force. These fractures become more remarkable as the powder compact becomes harder.

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This study was aimed at investigating of casting of hypereutectic Al-Si alloy strip by a different diameter twin roll caster. The roll size of the upper roll was φ250×W50, and that of lower roll was φ1000×W100. Roll-load was set low enough to prevent the sticking of the strip. Both of the rolls were water-cooled. The solidification length of upper roll was 60mm, and that of the lower roll was 100mm. The upper roll was tilted at 25 degree to casting direction from top of the lower roll. The roll speed was operated at 10m/min, 15m/min and 20m/min. The initial roll gap was 1mm. The mold lubricant was not used, and this increased heat transfer. Casting of the strip of Al-25%Si-alloy was possible by the different diameter twin roll caster made. The hot rolling could be operated at 500℃ without crack on the surface. The as-cast strip was hot-rolled down to 1.5mm, and this strip was cold-rolled down to 1mm after annealing. The eutectic Si of as-cast strip became fine granular by the effect of the rapid solidification. The good formability of the roll cast Al-25%Si was by the effect of the fine and globular eutectic Si.

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Roll casting of three layers of aluminum alloy clad strip was tried using a different diameter twin roll caster. This caster was equipped with a lower roll of 1500mm in diameter and an upper roll of 250mm in diameter, and the width of these rolls was 50mm. In this study, the first layer and the third layer was Al-Mn alloy, and the second layer was Al-Si alloy. The three layers of clad strip could be cast directly from molten metal by one caster. The three layers of clad strip could be connected by very small forces on rolls, for example, 18N per unit width. The clad strip does not peel off at the interface after cyclic bending test. In this way, the three layers of clad strip were connected strongly. The connecting interfaces were clear and Si of the second layer did not diffuse into the first and third layer.

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The vertical type tandem twin roll caster can make the clad strip by one process. This roll caster is composed of two vertical type twin roll casters. Two vertical type twin roll casters are set at the vertical position. In this study, the casting of the three layers of clad strip was tried by the vertical type tandem twin roll caster. The base strip was cast by the first (upper) caster. The overlay strips were cast by the second (lower) caster. The material of the base strip was AA8079. The material of the overlay strips was AA6022. The roll speed was 30m/min. The melt temperature of the base strip was 700℃. The melt temperature of the overlay strips was 750℃. The three layers clad strip could be cast by the vertical type tandem twin roll caster. The joining condition of the clad strip was investigated by EPMA and bending test. The diffusion area between the strips was very narrow. The interface between the strips was clear and flat. The strips were bonded firmly.

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A vertical type twin roll caster for strip casting of aluminum alloys was devised. The strip, which was thinner than 3mm, could be cast at speeds higher than 60m/min. Features of the twin roll caster are as below. Mild steel rolls were used in order to increase the casting speed. Roll coating occurs in casting of Al-Mg alloy. Therefore, the lubricant, that resists heat transfer between the roll and strip, was not used in this study. Low superheat casting was carried out in order to improve microstructure of the strip. The low temperature casting was useful to make the intermatallic of impurity fine. In the present study, effect of a high-speed and high-cooling rate twin roll caster on the recycled aluminum alloy was investigated. Fe, which content increases in the recycled aluminum alloy, was added as impurity to 5182. The roll caster was useful to decrease the influence of impurity Fe.

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The micro-forming of melt-spun Al-14 mass%Si was tried by the cold rolling. The nozzle pressing melt sinning method was adopted. The nozzle pressing melt spinning method was useful to improve the wetting pattern on the roll contact surface of the strip. The nozzle-pressing melt spinning process could cast the rapidly solidified foil at the thickness of 0.2mm. This was the thinnest foil which was suitable for the cold rolling. The Al-14 mass%Si was near to the eutectic at the cooling rate of the nozzle pressing melt sinning method. Therefore, the grain was very fine. The eutectic Si around the roll contact surface was about 0.3μm. The as-cast foil was cold rolled by Cr-plate-roll down to 0.1mm in order to improve the surface of the foil. Buffing was operated on the roll contact surface of the strip. V-mold was machined on the Ni plate operated on the roll surface. The depth of the V-groove was 1, 3, 5 and 10μm. The rolling speed of the mold roll was 1m/min. The micro bulge was mold on the roll contact surface of the foil. The height of the micro-bulge was about 0.2μm lower than the depth of the V-groove. The rolling direction was formed better than the lateral direction. It became clear that crystal alloy could be micro-formed by the cold rolling.

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Magnesium alloy is one of the light metallic materials which are utilized in industry, but it is difficult to do its plastic working in the ordinary temperature. After performing of AZX311 magnesium alloy thin plate, the material has a performance of high drawing greatly. In this study, after preforming by rolling processing, the preforming material has more drawn cup height without concerning the strain rate, e.g. high preforming material (reduction in thickness: 34%×2) is able to be formed under drawing speed in the region of low drawing speed (30〜180mm/min) at 100℃.

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Direct extrusion of AZ61 chips has been developed successfully. This method is able to get more reduction of extrusion load by comparison with the former casting and powder compaction molding. And, mechanical strength of the extrusion sections by this method becomes same as the others. For example, the density of extrusion section becomes 1.78 constantly, and the yield strength also becomes about 330MPa under extrusion temperature 400 degree Celsius. So, it seems to be the same as another forming product. It will be good for saving energy since forming cycle can be decreased by comparison with former techniques.

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It is known that the technology of computer held has rapidly advanced in recent years, and it is useful for the application of the various simulations. In case of the aluminum extrusion, there are many simulation reports Fluid Dynamics or Large Deformation, but there are a few reports for the metal flow condition of hollow dei extrusion in general. In this paper, the simulation technology of the metal flow condition with hollow dei extrusion is applied, and especially the metal flow are investigated experimentally and theoretically.

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Performance of six fine thermocouples of type-K, which were fabricated to weld a chromel wire and an alumel wire of 50μm by non-contact discharge welding method, was examined. The sizes of the hot junction were estimated from SEM images, and the response rates were measured by blowing hot air for a short period. The sizes of hot junctions ranging from 43 to 126μm can be controlled by the butt angle of two wires before the welding. The size tends to decrease with an increasing butt angle, and it was less than 100μm when the butt angle is larger than 100 degrees. The ratio of the size of hot junction to wire diameter is smaller than common thermocouples even if the butt angle is greater than 100 degrees. The response rate increases with a decrease in the size of the junction.

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We have developed a microwelding technique using micro electric discharge, and reported that gold particles of 60-80μm in diameter can be welded to a gold substrate. Here, two thin wires of 50μm in diameter, an alumel wire and a chromel wire, were welded to make fine thermocouple by the above microwelding method. The two wires were fixed to butt their tips. Discharge was generated for about 0.5 seconds by applying 5kV to a tungsten needle placed above the tips. After repeated discharges, the tips were melted and a junction was formed. The butt angle is an important factor for the size of the junction. It was less than 2 times of the wire diameter, when the butt angle is greater than 100 degrees.

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Objective of the present experimental investigation is to clarify the influence of the moist air relative humidity (RH=10-70%) on the properties of fretting friction and wear of steels under grease lubrication. Ball (bearing steel, JIS SUJ 2) on disk (carbon steel, JIS S15C) type fretting tests, for various amounts of grease supplied before each test at the punctual contact between ball and disk, were conducted at 50μm relative slip amplitude. Maximum values of the friction coefficient and the disk wear rate decrease at augmentation of the grease amount. Wear rate appears as unaffected by the RH variation for an amount of grease exceeding 0.02g, this representing the minimum amount necessary to avoid the grease film breakdown.

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Spot-welding is widely used in the various fields of engineering and industries. Since the size and quality of the nugget which is melted and re-solidified part of a welding are closely related to the strength of the welded structure, it is important to evaluate the shape and mechanical property of the nugget. In this work, an air-coupled ultrasound technique with focused transducers has been used for non-contact measurements of a spot welding. C-scan measurements were performed in pitch-catch configuration using a pair of focused transducers operating with tone burst waves at 0.4MHz. Signal processing techniques, such as an averaging, a band-pass filtering, and a matched filtering are employed to improve the signal to noise ratio of the measured signals. It has been found that the C-scan images with the matched filtering have a high signal to noise ratio even though a small number of data is used for averaging.

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The crystallographic orientation changes during fatigue crack initiation process in ultra-low carbon steel were evaluated by the electron backscattered diffraction (EBSD). EBSD measurement and fatigue test were alternately carried out using a small specimen, and the change of crystallographic orientation at the identical area was successfully evaluated. Based on the measurements, three crystallographic orientation parameters, Image Quality (IQ), Kernel Average Misorientation (KAM), Grain Reference Orientation Deviation (GROD) were calculated. IQ, which represents diffraction pattern quality and is lowered by increase of crystalline defects, exhibited irregular variation. KAM, which is the misorientation between neighboring measuring points in identical grain, increased until fatigue crack initiation and then decreased. However, KAM was strongly dependent on the step size of scanning electron beam. GROD, which is misorientation between each measuring points and the datum orientation (in this study, it is defined as the orientation at the measuring point with the minimum KAM in each grains), increased until fatigue crack initiation and then remained constant. These results indicated that GROD is the most useful parameter among those three parameters for evaluation of the fatigue damage dominating fatigue crack initiation.

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A new remote nondestructive inspection technique, based on thermoelastic temperature measurement by infrared thermography, is developed for detection and evaluation of fatigue cracks propagating from welded joints in steel bridges. Fatigue cracks are detected from localized high thermoelastic temperature change at crack tips due to stress singularity under variable loading from traffics on the bridge. Self-reference lock-in data processing technique is developed for the improvement of signal/noise ratio in the crack detection process. The technique makes it possible to perform correlation processing without an external reference signal. In this paper, self-reference lock-in thermography is applied for crack identification based on the detection of the singular stress field in the vicinity of crack tips. Experiments are conducted using steel deck specimen, which simulates an actual steel bridge using steel deck in crack propagation test. It is found that significant stress concentration zone can be observed near the crack front, which enabled us to detect through deck type fatigue cracks.

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An evaluation method of IC-chip pick-up performance using an adhesive tape is proposed. IC-chip with an adhesive layer of the adhesive tape is peeled off a base material in pick-up process, by needles sticking out backside of the base material. In the proposed evaluation method, the peel energy on various peel speeds of an adhesive tape is measured by peel test. Finite element method is applied to calculate energy release rate of pick-up process on various peel lengths. From these results, the correlation between peel speeds and peel lengths of pick-up process is obtained. The pick-up time is calculated from the correlation. Excellent pick-up performance is expected if the calculated pick-up time is shorter than actual process time. The proposed method was validated by comparing with actual pick-up process. 100, 200 and 300μm thickness chips were used for the validation. The result of actual pick-up test shows good agreement with the estimated result.

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Fatigue failure accompanied by ratchet deformation is well known as one of the failure modes of pressurized pipes under high-level cyclic load. In this research, the process of failure of such pipes was investigated based on the experimental result in which a straight pipe failed by repeatedly increasing cyclic input displacement amplitude in stages. The strain behavior, moment-deflection relationship, and observed damage were compared with the stress level used in the seismic design of the piping system. As a result, no significant damage was observed and the moment-deflection relationship remained almost linear within the primary stress limit of 3S_m, although the strain showed elastic-plastic behavior at some measurement points. In the experiment, damage was observed at the applied load levels of approximately 5S_m of the primary stress, and 0.15 and more of the fatigue damage index, i.e., the usage factor based on the design. The test results showed that there is a certain time margin before failure occurs to actual piping systems, compared with its designed stress limitation.

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NiTi shape memory alloy (SMA) is expected as medical devises utilizing the shape memory effect. However, release of the Ni ions from the SMA into the human body is one of the significant issues to be solved because Ni ions cause the allergetic reaction. Diamond-like carbon (DLC) coating is one of the promising materials that can prevent the release of such ions. To use DLC as coating materials onto NiTi, fatigue strength to endure cyclic bending of the SMA substrate is required. Although conventional DLC coating is very brittle and show week adhesive strength to metallic substrate, the addition of metal into a DLC matrix is one of the possibility to get good adhesiveness and bending flexibility. In this study, the fatigue strength of tungsten-containing DLC coating on SMA plate was investigated. DLC was deposited on a SMA plate by radio-frequency chemical vapor deposition (RFCVD) and also co-sputtering of metal target. The fatigue strength of DLC has been characterized by applying 1% cyclic bending strain. The surfaces of the coatings were observed after bending test using a scanning electron microscope (SEM), a optical microscope and an atomic force microscope (AFM). In the result, no cracks and interface delamination were obsearved up to 10^5 cycles.

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We introduce a method of predicting macroscopic yield strength of polycrystalline metals subjected to plastic forming by applying the micro-macro decoupling analysis method. The macroscopic plastic forming problem is assumed to be a three-stage forming process and is simulated with a single finite element in this study. At the same time, a polycrystalline aggregate composed of several crystal grains is adopted as a microstructure and is regarded as a numerical specimen for numerical material tests based on the homogenization theory. After simulating the macro-scale forming process with macroscopic approximate constitutive model, we apply the resulting macroscopic deformation histories to the microstrcutre to obtain the numerical specimen that enables us to evaluate the post-forming yield strengths. By performing the equivalent micro-macro coupling analysis and comparing the results with those by the coupling method, we demonstrate the capability of the proposed method in predicting the anisotropy in the macroscopic yield strength.

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We have investigated the properties of the numerical methods for analyzing the stress wave propagation which is caused by a longitudinal impact of a cylindrical bar by a one-dimensional model. It is shown that the one-dimensional model possesses some physical properties for the numerical calculation by applying an exponential function as the constitutive equation. We have treated the numerical method which keeps the physical properties intrinsically possessed by the system. Namely, we have focused on Cellular Automaton (CA) scheme which is derived from the integrable difference scheme by means of the ultra discrete limit. We have compared the CA scheme with the integrable difference scheme and the general-purpose methods such as Euler method and Leapfrog method on the efficiency of the calculation. The properties of the CA scheme for the present analysis are revealed. Especially, it is shown that the CA scheme can maintain a certain accuracy for the long time behavior of the stress wave propagation and the interaction between the waves.

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It is well-known that woven fabric composite materials have high performance. It is, however, very difficult to access their mechanical behaviours due to their complexity of microstructual morphological geometry. Authors proposed Optical Coherence Straingraphy (OCS), which could visualize micro mechanical information tomographically and nondestructively from speckle deformation between synthetic images obtained by Optical Coherence Tomography. This is basically constructed by recursive cross-correlation technique and weighted moving least square method, which can offer cross-sectional strain distribution at the resolution of micrometer scale. In this study, applying OCS to plain-woven fiber-reinforced rubbers, the micro mechanical behaviour under uniaxial tensile load was visualized as an experimental strain distribution, which was verified by the numerical results based on image-based simulation. Consequently, tomographic strain distributions calculated by OCS agreed qualitatively with the simulated ones at the resolution of micro scale. It was, therefore, concluded that OCS could provide an experimentally powerful concept for the microstructual design of composite materials, as a nondestructive visualizing tool.

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This paper describes the effects of stress ratio on the ΔK_<th> improved by overload. High-tension steel (HT540) and aluminum alloy (A7075) were prepared as test materials. Tensile overload was applied to compact tension specimen, subsequently fatigue tests were carried out at stress ratio R=0.1 or 0.5. The main conclusions are as follows; (1) The value of ΔK_<th> increased with increasing of the tensile overload. (2) The effect of overload on ΔK_<th> did not differ between HT540 and A7075. (3) The improvement ratio of ΔK_<th> at R=0.1 was larger than that at R=0.5.

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