This paper describes the anisotropy of yield surface, which is formed during a large pre-deformation. In a series of our previous studies, the shape of yield surface when the simple shear in the reverse direction is applied after the large simple shear in the forward direction have been examined. Since the anisotropy arises on the reverse shear side, it is revealed that the anisotropy is newly formed during process of the reverse shear. In the present study, in order to investigate the intermediate status of the development of anisotropy, the experiments are conducted with the small reverse shear condition as compared with the previous experimental condition. Then, the shape of yield surface estimated in this study is compared with the result in our previous report.

In our previous studies, the yield stress when the cyclic loads are subjected to the specimens after applying the large pre-deformation has been examined. However, in these studies, the type of pre-deformation and the type of deformation in the cyclic loads are the same, and experiments when these deformation types are different have not been conducted yet. Therefore, in this study, the yield stress generated under cyclic loads of tension and compression after applying large simple shear is examined. As for the estimation method of yield stress in each cycle, the slope of tangent in the deviatoric stress and deviatoric strain curve is used. Then, the variation of yield stress with an increase of the number of cycle is examined under the different size of pre-deformation and strain amplitude. Moreover, the experimental results in this study are compared with previous results, which are obtained under cyclic loads of tension and compression after applying large uniaxial tension.

The temperature cycle was given to the single crystal silicon solar cell module and the relationship between the effect of temperature cycle on power generation efficiency and de-bonding progression was investigated. Measurement of delamination location by immersion ultrasonic single probe method was carried out to evaluate the de-bonding mechanism.

The nonlinear bending equation for a slender, tapered cantilever beam made of axially functionally graded material (FGM) with a transverse load applied at the tip, undergoing large deflections, is solved by the Runge-Kutta method. Solutions are obtained for round cross-sections, for varying degrees of both taper and Young's modulus and are compared with existing values obtained in previous research. Sets of deflection and stress curves are also obtained, from which the deflection and stress at any point in the beam may be computed.

Because of the excellent corrosion resistance, weldability and mechanical properties, SUS304 is widely used for manufacturing industrial equipment and daily necessities. SUS 304 is an austenitic stainless steel, so its physical properties also have characteristics that greatly change depending on the amount of martensite in the material. The purpose of this research is to develop a simulation method to predict the residual stress of SUS304 considering martensitic transformation.

We developed a new technique for evaluating the fatigue life of welding using strain gradient parameters. These parameters are composed of two parameters. One of them H_ε shows the magnitude of the strain concentration points, and the other parameters λ_ε shows the gradient of strain concentration points. These parameters can arrange the fatigue life of welding N in an equation called as face fatigue life. The equation’s basic form is logN=alogH_ε+bλ_ε+c (a,b,c are constant). In this report, we considered how to use the equation for the design process and showed two efficient use cases. One is the use of logN-logH_ε with constant λ_ε. This relationship shows the load tolerance and required plate thickness. The other is the use of logN-λ_ε with const H_ε. This relationship shows the crack length tolerance and required a radius of curvature of the strain concentration points of welding.

Influence of large slip deformation with overloading on the following slip deformation behavior under the cyclic deformation is investigated by a finite element crystal plasticity analysis code. Accumulation of geometrically necessary dislocations (GNDs) and statically stored dislocations (SSDs) with non-uniform deformation around the grain boundary triple junction of tri-crystal models subjected to cyclic deformation are studied in detail. Results of the analysis shown that non-uniform deformation and the high density of GNDs and SSDs accumulated around the grain boundary triple junction with overloading, after unloading, these dislocation density are decreased and dislocation patterns are attenuated. However, attenuated dislocation patterns are without disappearing and remain when average tensile stress and strain of tri-crystal models are 0, and develop non-uniform deformation and accumulation of dislocation in the following cyclic deformation. Mechanism of the residual dislocation develop non-uniform deformation in the following cyclic deformation are discussed from the viewpoint of disclination type deformation around the grain boundary triple junction of tri-crystal models.

When an unexpected overload or underload was applied a cracked material during usual operation under constant stress amplitude, an acceleration or deceleration of the crack growth was observed depending on the experimental conditions. In the present study, a method of detecting the application of an unexpected dangerous load was investigated. In some cases, the acceleration of crack growth brings catastrophic failure in machine structure. Therefore, it is useful for machine maintenance to know whether an unexpected load was applied or not by doing daily inspection. In the present study by using center-crack specimen, a simple method of detecting application of overload or underload was investigated.

Tension-tension axial fatigue tests were conducted using ultrafine-grained commercial purity (CP) grade 2 titanium (Ti) thin foils with four different thicknesses, 13, 20, 30 and 50 μm, processed by multi-directional forging (MDFing) and the fatigue properties were investigated. All of the foils exhibited higher strengths in static tensile and fatigue tests than the conventional cold-rolled CP grade 2 Ti irrespective of foil thicknesses. The static and fatigue strengths of all the foils were comparable while thinner foils tended to exhibit higher strengths.

In this study, the effect of stress rate on fatigue strength of PBO (Poly-p-Phenylene Benzobisoxazole) fiber with kinking damage was investigated in monofilament fatigue tests. High-modulus type PBO fiber (HM-PBO fiber) was used in the experiment. Kinking damages was created on surface of virgin fiber by winding bundle fibers to steel rod, set of 0.625 mm. Load-controlled fatigue tests were carried out using a sinusoidal load with frequency of 10 Hz and stress ratio of R = 0.1, 0.5 and 0.7, the load cell capacity was 10 N. Because the stress ratio can be adjusted between 0.1 and 0.7, it can be unambiguously arranged fatigue strength. The S - N curve of PBO fiber indicates kink damage with maximum stress at stress ratios of 0.5 and 0.7. In addition, the fatigue strength with a stress ratio of 0.1 is located on the lower strength side than the stress ratio of 0.5 or 0.7.

The brake hose made of austenitic stainless steel SUS 304 has several excellent characteristics such as a linear operation feeling during brake, light weight, impact resistance, etc. as compared with conventional rubber brake hose. In this study, we clarify the influence of the change in physical properties due to the process induced martensitic transformation in SUS 304 on fatigue durability of torsion coil springs for brake hoses for motorcycles, which is a security part, and propose a prediction method for fatigue life and an optimum processing method.

Ultra-high strength steels with more than 980 MPa tensile strength will be used for weight saving of boby and underboby parts and improvement of fuel efficiency of automobiles. However, in the case of ultra-high strength steels with a notch, fatigue strength drastically decreases in general, namely effect of notch sensitivity. In this study, fatigue limits and the notch sensitivity for 590 MPa and 980 MPa class bainitic steels were evaluated using steel plate specimens with three different notch shapes (stress concentration factors α＝1.0 (without notch), 2.6, and 3.6) by four-point bending fatigue tests. The notch sensitivity of 980 MPa steel plate specimens was higher than that of 590 MPa steel plate specimens. However, the results of notch sensitivity of plate specimens were obviously lower than that of cylindrical specimens made of bainitic ultra-high strength steels or hitherto known cylindrical specimens. It is thought that the reason is size and shape effects.

Cast aluminum alloys are promising from the perspective of its high specific strength and high cost effectiveness. However, cast aluminum alloys inevitably contain casting defects which degrade its fatigue strength, and it leads to the low reliability. It was observed in the experiments that the cracking was initiated by the fracture of Si particles or debonding of Al-Si interface. In this study, the image-based finite element analyses were carried out by using synchrotron X-ray CT images to elucidate the crack initiation mechanism of cast aluminum alloy under low-cycle fatigue. To examine the difference of mechanisms between fracture of Si particle and debonding of Al-Si interface, the finite element elastic-plastic analyses of five models for the fractured or debonded particles were performed under ten cycles of fatigue loading. From the numerical results, the Si particle with large volume was fractured because of high stress concentration, while the Si particle neighboring closely to intermitallics was debonded since the large plastic deformation of the aluminum matrix between Si and IMC particles.

Cast aluminum alloys have been widely used in transportation equipment because of its high productivity and high specific strength. However, the cast aluminum alloys have low reliability of fatigue strength caused from inevitable casting defect. In our previous work, from the low cycle fatigue test and in situ synchrotron X-ray CT observation of the cast aluminum alloy, it was found that the crack initiation of the cast aluminum alloy was occurred by the fracture of Si particles. In this study, the fracture of Si particle was regarded as the crack initiation, and the geometrical characteristic of fractured Si particle was investigated. The fractured and intact Si particles were identified by chronological CT observation. Geometrical analyses of Si particles were conducted by using high resolution CT images, while Si particles were extracted by an appropriate threshold value of brightness. Geometrical parameters of a few hundreds of thousand Si particles in a specimen were analyzed, then they were evaluated statistically. The effective geometrical parameters were suggested to determine the condition of particle fracture.

Nanoindentation is a useful tool for measuring regional elastic modulus. However, the elastic moduli of some anisotropic single crystals measured by nanoindentation are often different from theoretical value that is calculated by elastic constants from ultrasonic method. The main cause of the difference is still incompletely understood. One probable reason is a deviation from apparent contact area due to plastic deformation such as pile-up. Therefore, it is effective to evaluate the indentation modulus during fully elastic deformation. In this study, we investigated the cause of the problem above by measuring indentation moduli of some single crystals (4H-SiC, sapphire, quartz, tungsten, CaF₂ and silicon) with a Berkovich and a spherical indenter. The tendency of the comparison between experimental and theoretical indentation moduli is different depending on the measuring materials. To evaluate the indentation modulus independent of the measuring method, it suggests being useful to carry out completely elastic indentation with spherical indenter.

In this study, a semi-nondestructive procedure for stress - strain curve estimation was developed using instrumented indentation technique. Additionally, to estimate local stress - strain curve in the welds with mechanical heterogeneity, a relation between spherical indentation size and measuring range of mechanical property was quantified by using finite element analysis of spherical indentation technique. First, the developed technique was applied to estimate mechanical property of low alloy steel to validate the estimation accuracy. Next, the developed technique was applied to estimate mechanical properties of low alloy steel welds with mechanical heterogeneity. To obtain mechanical heterogeneity in welds, two pass welding was performed on the surface of material with a certain level of transverse distance. With appropriate indentation size, distinguished stress - strain curve was successfully obtained at each position, such as weld metal, heat affected zone and base metal. Thus, it was concluded that the developed technique was useful to estimate mechanical heterogeneity in the welds with a high degree of accuracy through simple process.

In order to evaluate hardness of a knife edge of swords, the damping hardness of a vegetable knife made of steel was investigated by using Herbert pendulum type hardness test. Stably swing behavior of Herbert pendulum on the knife edge of the vegetable knife was observed. Reasonable damping hardness of the knife edge of the vegetable knife can be obtained, although a knife edge is special shape as specimen. Therefore, hardness of a knife edge of swords can be reasonably evaluated by using the Herbert hardness test.

In this paper, wood flours having a microfibrillated cellulose network on the surface were proposed for wood plastic composites to improve mechanical properties. Wood flours were fabricated through wet milling process. The average of particle size was arranged to approximately 26μm. Then the surface of wood flours was melted by ionic liquid and the microfibrillated cellulose network was generated. The thinning woods such as chamaecyparis cypress and cedar were utilized for raw material. 1-Butyl-3-Methylimidazolium chloride was employed for ionic liquid. The nature of ionic liquid treated wood flours were observed by SEM. The test specimen of wood plastic composites was fabricated by injection molding. Polypropylene was used for matrix. The influence of ionic liquid treatment on mechanical properties was discussed.

Currently, biodegradable plastics capable of soil decomposition are attracting attention, but they have drawbacks such as low strength. Therefore, it is necessary to reinforce strength by using biodegradable fibers such as natural fibers. However, there are dispersions in strength of natural fibers. In this paper, we propose a method to reduce dispersions in strength of palm fibers, which is a natural fiber. Palm fiber ware subjected to a tensile test using a tensile tester at a speed of 1.8mm/sec, and Weibull analysis was performed. As a result, for fibers with a cross sectional area between 0.0582mm² and 0.0118mm², the shape parameter of strength was 5.4 or more. This is the same shape parameter as glass fiber. From this, it was found that there is a possibility of reducing dispersions in strength by managing fibers with the cross sectional area. Also, the shape parameter of the strength of the fiber with large cross section became lower. We considered the vascular bundle to be the cause of this and observed the cross section. As a result, as the cross sectional area increases, the ratio of the cross sectional area of the vascular bundle to the cross sectional area of the fiber is widely distributed from 1% to 20%. From this, it can be concluded that the cross sectional area ratio of the vascular bundle is widely distributed as one of the reasons why the shape parameters are lowered when the cross sectional area of the fiber is large.

From the viewpoint of improving both the crash safety and the fuel efficiency, various shaped thin-walled structures have been utilized as energy absorbers of automobiles such as crash box, front side member and so forth. In order to effeciently absorb energy in the crash, those are asked to have appropriate strength/weight ratios for respective materials and structures. In this study, impact (3~4m/s) crushing tests of some thin-walled regular polygonal tubes were performed by the drop weight testing device for crush angles of 0, 10, 15, and 20° to investigate the transition from the axial collapse mode to the bending one. The specimen material is annealed S25C that shows high strain rate dependence. This transition occurred at the crush angle around 15° for square and regular pentagonal tubes. The transition causes abrupt decrease of the mean buckling load, which is no longer so sensitive to the crush angle under the bending collapse mode. The comparison with the results of quasi-static and low-speed crushing tests also shows that the mean buckling load under the axial collapse mode considerably increases with the strain rate, while that under the bending one hardly grows.

Honeycomb core sandwich panel (hereafter, HSP for brevity) are superior in impact absorption under whole surface compression. However, impact properties of HSP under local compression such as drop weight impact are affected by mechanical properties of the plate as the face sheet in addition to the core layer. In this study, a simple mechanical model of the double layer HSP subjected to the drop weight impact was proposed based on the experimental results. The numerical analysis by the proposed mechanical model was conducted. From test results, when the strength of the core was high, the load-displacement curve and the deflection curve of the double layer HSP were successfully reproduced. On the other hand, when the strength of the core was weak, some of calculated deflection curves disagreed with the measured deflection curves. It showed the range of the application of the proposed mechanical model.

In this research, in order to develop a simulation method of drop impact of cardboard, the anisotropic elastic modulus of corrugated cardboard is decided by material test and it is used to compare the drop test and the drop impact simulation and evaluate the maximum acceleration of the article . It is known that buckling occurs in the corrugated board at the time of a drop impact and greatly affects the maximum acceleration. The relationship between this buckling and the maximum acceleration is elucidated, and the aim is to establish a method of simulating fall impact of corrugated cardboard when considering buckling.

Recently, many new technologies developments relating to seismic design of bridge piers against earthquakes have been proposed due to improved analysis techniques. From this, the seismic performance of the pier has been improved. When force of an earthquake is generated in the pier of a ramen structure, bending failure occurs at the base and shear deformation occurs at the center of the beam. Normally, metal materials can absorb the energy by being plasticized from earthquakes. However, when shear buckling is happened, the hysteresis of the material can not be maintained and the amount of energy absorption decreases. In this research, focusing on the ramen structure, we aim at establish a nonlinear finite element method analysis technique for shear buckling by three-dimensional elasto-plastic dynamic response analysis for the earthquakes. Then, materials with low stress and high ductility are installed in the central part of the beam as a fail-safe, and reinforcement is carried out with the stiffener. From this reason, energy can be absorbed and destruction can be limited by resist shear deformation.

This paper presents a new numerical simulation model for hydraulic injection to deep underground. For deep underground exploitation, hydraulic injection is used to enhance the permeability of the formation and produce engineered reservoirs. Especially in geothermal energy exploitation, there are many sites that underground permeability is too low although rock's temperature is high enough. Hydraulic injection is useful to enhance rock's permeability between injection well and production well. However, during injection, earthquakes can be induced so it is necessary to reduce the risk of it. For continuous exploitation, it is necessary to solve shear destruction behavior of fractures. In this research, we develop the reservoir model that consider only one vertical fracture based on the acoustic emission result that seismic centers were localized on one plane. This model considers reservoir creation by shear dilation, and supposes existence of asperities on fracture that cause earthquake when they break. Using this reservoir model, we can analyze time dependent earthquake occurrence and reservoir creation behavior.

The prevention of excessive deformation by thermal ratcheting is important in the design of high-temperature components of fast breeder reactors (FBR). In an experimental study that simulated a fast breeder reactor vessel near the coolant surface, it was reported that the long distance travel of temperature distribution causes a new type of thermal ratcheting, even in the absence of primary stress. In this paper, based on the results of inelastic finite element analyses, we investigated saturation behavior of thermal ratcheting strain due to long range travel of temperature distribution. As a result, we revealed that the long distance travel of temperature distribution generates plastic strain distribution made maximum at the central part. Because of the shape of the generated strain distribution, the residual stress accumulates even at the central part of the region passed through the temperature distribution. In the case with excessive long traveling of temperature distribution, the region with plastic deformation extended to the surrounding region. Otherwise, sufficient magnitude of residual stress to cause shakedown behavior accumulated on entire region, and the accumulation of the plastic strain saturated.

In the automobile industry, the weight reduction of the vehicle body is being promoted by the multi-material structure using partially light metals. Mechanical Joints are effective for dissimilar metal Joints used for multi-material structure. Bolted joint, which is a typical example of mechanical joints, is widely used as a method that are easy to assemble and disassemble. It is important to monitor the cramping load of the bolt in order to prevent bolt from falling off. The conventional study has been clarified that the natural frequency of the bolted joints decreases by the reduction in the stiffness of the joint surface of the bolted joints due to the decrease in the cramping load of the bolt. In this study, a novel method to extract the surface texture parameters by data assimilation from the change of the natural frequency with respect to the cramping load of the bolted joints has been developed and applied to verify the tightening condition. Hammering test was conducted by the proposed method, and the fastened state was evaluated. The result shows that experimental result of natural frequency and data assimilation are matched, and clamping load can be estimated. In the dissimilar metal joints, it was found that the tendency of increasing the natural frequency with respect to the clamping load is insensitive in the analysis.

There are many defects found in a non-destructive inspection at areas of stress concentration like a corners of the welded materials and so on. However, the mainstreams of the inspection are ultrasonic inspection, radiographic testing and magnetic particle testing, and they need an ability to find crack, defect and so on. Therefore, we will develop technology for non-destructive inspection using mechanoluminescence materials as a simple method to find internal defects. We apply the mechanoluminescence materials on the test piece which has defects. It proves that mechanoluminescence materials can find out the defects and stress concentration.

The present work nondestructively observed the dual-phase microstructure of Ti-6Al-4V using synchrotron radiation micro-CT imaging at Spring-8 to establish a nondestructive inspection method which clarifies microstructural effect on the internal fatigue fracture. An imaging system with a small pixel size of 0.23 μm/pixel and the field of view of 0.47 mm × 0.47 mm was used to finely resolve the grains with an average size of 10 μm. The needle-shape-specimen whose diameter changes along the longitudinal direction was used to determine the maximum diameter which enables to obtain a clear image of grains. The absorption images inside the specimen at the sections with the diameter less than 0.45 mm resolved the internal grains regardless of the diameter; however the contrast between α phase and β phase was not so high. The phase retrieval processing was applied to the data set in order to obtain better contrast. The phase retrieval images provided the significant contrast between two phases. Based on these results, the micro-CT imaging was conducted on the hourglass-shape-specimen with a diameter of 0.45 mm, in which an internal crack had already initiated and propagated due to the cyclic loading of 10⁷. As a result, the internal crack and its surrounding grains were clearly observed; the positional relation between the crack and the grains could be examined on the image. This result indicates that the internal fracture process can be investigated in terms of the microstructure using micro-CT imaging.

The purpose of this study is to elucidate the status of the local deformation generated under large deformation, which is measured by using the image analysis. The Natural Strain theory is the effective strain representation, which can remove the rigid body rotation from the shearing strain components and satisfy the additive law of strain, so in this research, the Natural Strain theory is effectively used in the image analysis. In order to elucidate the effect of change in material properties on the progress of local deformation, the local deformation generated under tensile tests is investigated by using the test pieces, which is preliminary applied a simple shear. As for the pre-deformation of simple shear, three different types of the deformation path are examined in this study. Then, the effects of these pre-deformation on the progress of local deformation during tensile deformation are revealed.

This study describes a newly proposed “symmetric quadrant sampling method” for the simulation-based estimation of the structural failure probability. First, using the standardized normal probability density function, a sample is generated as a real sample in a designated quadrant. Applying the previously proposed “inter-quadrant relational expression,” the coordinates of the real sample point is converted and determined to those of another sample point as a pseudo sample point in a randomly selected sampling target quadrant. The sampling target quadrants are composed of a certain specified number. Next, by applying the axial symmetric property between two quadrants, one more pseudo sample point corresponding to one generated in first can be determined in the symmetric quadrant. By using the “symmetric quadrant sampling method,” every iteration of generating one real sample yields two pseudo samples in the specified number of quadrants, respectively. The simulation is executed by using all of pseudo samples thus determined. Numerical example to estimate the failure probability of structural system described by large numbers of basic random variables, based on the directional simulation using the “symmetric quadrant sampling method,” shows that the proposed method gives effectively accurate estimations of structural failure probabilities.

Most of coronary artery stents are manufactured from small diameter metal tubes. Therefore, evaluation of mechanical properties of the metal tube is important to guarantee the required stent performance. Although uniaxial tensile test is often employed to obtain a stress-strain relation in axial direction of metal tube, it is not suitable to evaluate the mechanical properties in circumferential direction. In this study, we focused on a tube end flaring test to evaluate the circumferential mechanical properties of small-diameter AZ31 magnesium alloy tube, which is expected to be used for bio-absorbable coronary artery stent. Finite element analysis was performed to investigate the deformation characteristics of the tube in the tube end flaring test. The experimental investigation was also conducted on AZ31 magnesium alloy tube by means of a lab-made test instrument. The results revealed the possibility to evaluate the mechanical properties of the small diameter magnesium alloy tube by the tube end flaring test.

There is a risk that FW (Filament Wound) composite pressure vessel is exposed to high temperature by a fire accident of Fuel Cell Vehicles. This paper aimed to develop a method of estimating the burst pressure from the temperature and time that FW composite pressure vessel is exposed. Vessels (Type-3, Volume 2.1L, Maximum pressure 19.4MPa) were heated in the atmosphere six different thermal histories (Room temperature, 493K-1hour, 513K-1hour, 533K-1hour, 553K-1hour, 573K-1hour). Heat tests, burst tests at room temperature, fractography, cross-sectional observation of CFRP, ultrasonic testing, and stress analysis were conducted for FW composite pressure vessels. The burst pressure of the vessel (573K-1hour) decreased. Delamination was observed in the section of the vessels (497K-1hour, 513K-1hour). The higher the exposure temperature, the lower the reflection intensity of CFRP.

When honeycomb core sandwich panel (hereafter, HSP for brevity) is used as a floor panel, a dent will be formed on the face sheet of the HSP. If the high toughness material such as Carbon fiber reinforced plastics (hereafter, CFRP for brevity) is used as the face sheet, it is thought that the period for use as the floor panel will extend. In this study, a static local compression test and a local compression fatigue test was carried out on the HSP with the laminated the CFRP face sheets. From the static local compression test, it was found that the CFRP laminate broke depending on the bending stress. From the local compression fatigue test, the fatigue life was longer with the interface the number of laminated sheets when. It was confirmed that the fatigue life was prolonged when CFRP in the 45 ° direction was incorporated in the laminated structure. The core similarly collapsed of all HSPs during the fatigue. And no cracks occurred in the CFRP laminate.

The FW-CFRP / Al composite pressure vessel is a vessel in which the liner of Al alloy is covered with a carbon fiber reinforced plastic (CFRP) layer and a glass fiber reinforced plastic (GFRP) layer by the filament winding (FW) method. In order to reduce the weight and strengthening CFRP and Al alloy of vessels while maintaining safety, it is necessary to improve the accuracy of technology for quantitatively predicting the fracture origin of the vessels. Conventional research deals with FW-CFRP / Al composite pressure vessel as isotropic material, and calculations are performed on condition that the velocity of the elastic wave propagates on the surface of the CFRP does not depend on direction. However, when calculating the elastic wave velocity using the elastic modulus of CFRP, the speed varies by up to 3 times depending on its direction, and it is necessary to consider the anisotropy. The fracture origin at burst of FW-CFRP / Al composite pressure vessels was identified from the difference in the propagation time of elastic waves and compared with the results of fractographical observation. We have developed a position identification method considering its laminated structure and anisotropy of CFRP and showed its effectiveness.

Sandwich panel is easily deformed by local compressive load. In order to evaluate the mechanical property of the sandwich panel subjected to local compression, it is important to estimate the support reaction of the cell wall. This paper describes a novel method to estimate the support reaction by inverse analysis of the deformed shape data of the face sheet. In this method, the finite element method which is based on incremental strain theory is applied to the face sheet using the measured deflection of the face sheet as the boundary condition. Then it estimates the load of the face sheet that is equivalent to the support reaction. In order to demonstrate the validity of the proposed method, the experiment using the specimen with the cylindrical core material have been conducted. Then the inverse analysis was applied on the experimental data. The results show that the estimated distributions of the support reaction have good agreement with the correct value measured in the experiment.

0.5～1.0wt. % carbon nano-fiber (CNF) dispersed frame-resistant magnesium alloy was prepared by stir casting process. Starting materials were Mg-5wt%Al-3wt%Ca and VGCF as matrix and CNF. In order to disperse VGCF in alloy uniformly, Ni was coated on VGCF by electroless Ni plating before casting. As increasing VGCF contents, the microstructure of matrix in composites refined, but the aggregation of VGCF increased. As increasing VGCF content, hardness was increasing. On the other hand, the composites has high strength at 0.5wt. % VGCF composites. 0.5wt. % VGCF composites has higher proof strength and tensile strength than monolithic alloy.

Recently, Indium tin oxide (ITO) has been widely used as transparent conductive films (TCFs) in various electronic devices. However, ITO has many drawbacks such as high cost and brittleness. Nowadays, graphene is the ideal alternative for ITO because of its excellent transparency, electrical conductivity and mechanical flexibility by the effect of sp² hybridized orbital. However, the electrical properties of graphene TCFs are inferior to those of ITO so additional processing to improve electrical properties is required. Achieving the purpose, there is a number of studies on composite graphene and conductive materials such as Ag. And now, new simple, low-cost methods are required. In this study, we used the liquid plasma method to combine graphene and Ag. This is a low-cost, simple method for the hybridization. Then we made graphene / Ag hybridized TCFs using thin layer graphene-supported Ag and evaluated some characteristics. Finally, we acquired transmittance and sheet resistance of the graphene / Ag hybridized TCFs.

Titanium and its alloys have poor wear resistance. To improve their wear resistance, ceramic-particulate reinforced titanium matrix composites (TMCs) were fabricated by spark plasma sintering process (SPS). The influencing factors on wear resistance about TMCs in Taguchi Method are classified by the noise factors as load, sliding velocity, sliding distance, counterpart material, temperature, humidity, and the control factors as matrix material, shape of matrix, particle size of matrix, reinforcement material, and reinforcement volume fraction. In this study, the control factors were selected to optimize in them by the method. The experiments were conducted systematically based on L18 orthogonal array of the method. Wear tests were carried out using a three-ball-on-disk machine. The results indicated that the wear resistance of TMCs was affected by three factors, such as matrix material, reinforcement material, and reinforcement volume fraction. The Si3N4 reinforced hydride-dehydride Ti matrix composite with 10vol. % reinforcement showed good wear resistance.

A single-roll caster equipped with two scrapers and an unequal-diameter twin-roll caster equipped with two scrapers are proposed for casting clad strip without centerline porosity. Although usually found in roll cast 5182 strip, no centerline porosity occurred in the 5182 strip, which was cast by the unequal-diameter twin-roll caster equipped with two scrapers. The interface between the 5182 strips and the 3003 base strip was clear. Both roll casters could cast the clad strip at 30 m/min.

This study investigates the distribution of silicon on thin-walled die casting made of Al-25%Si alloy. The fluidity test piece with a thickness of 0.8mm was used, and the model of the heat sink was made of Al-25%Si alloy with a fin height of 35mm and a fin thickness of 0.5mm. The effect of the distribution of silicon on heat radiation performance was estimated. The obtained results are summarized as follows: (1) The distribution of silicon varies between the gate to the flow tip in the fluidity test piece made of Al-25%Si. (2) The volume of silicon at the gate side is not the same as that of silicon at the opposite side on the surface of the fin in the model of the heat sink made of Al-25%Si alloy. (3) The distribution of silicon has no influence on heat radiation performance in the model of the heat sink made of Al-25%Si alloy.

In recent years, lightweight heat sinks with high heat dissipation manufactured by die-casting are in demand. The material which is generally used in die-casting is ADC12 alloy. However, it is quite difficult to manufacture heat sinks using ADC12 alloy whose fin-top-thickness is thinner than 1mm. In this study, we used Al-25%Si alloy, which had been found more suitable to cast thinner and lighter heat sink models, and investigated how the rate of heat dissipation is influenced by the following factors; (1) kind of the alloy, (2) the thickness of the fin, (3) the height of the fin, (4) the thickness of the base and (5) the number of fins. Measurement results influenced on heat dissipation neither difference in thermal conductivity of the alloys nor thinning of the fins. Regarding the shape of heat sink models, increasing the fin height was effective for improving the heat dissipation under the experimental conditions.

Recently, the demand for aluminum alloy made of a wide variety of materials is increasing, especially its small lot production. Although Properzi continuous casting and rolling process is a widely used and highly efficient process to produce aluminum alloy rods, it is suitable for mass production. In this study, we tried a new process to produce a convex as-cast rod, using a single roll caster, which is usually used for producing thin strips. We developed a groove-type casting wheel. The effect of the flow speed of molten aluminum alloy and angle against the casting wheel when the molten was poured into caster on cross section of as-cast rod were investigated. With a trapezoidal shape of groove, solidification shrinkage occurred to the free solidified surface of as-cast rod. However, with a triangular shape of groove, the convex as-cast rod was produced when the pouring angle and the flow speed of molten aluminum alloy were within the appropriate range. Especially at the pouring angle of 40°, while the molten didn't fill the groove and the crystal gain size was larger than that at the pouring angle of 80°, the shape of the as-cast rod became closer to be circular and more appropriate in consideration of the rolling process.

We have developed a semi-continuous caster for a two-layer clad plate for sliding bearing. When the molten metal is poured into a moving mold, it is cooled and molded with a copper roll. Sidedam is a soft material. Therefore, the sidedam is pressed and cooled evenly with a copper roll. To produce a sliding bearing ,a three-layer clad plate consisting of Al-40% Sn-1%Cu alloy plate, an intermediate material and a base material is needed. We used A1050 and ADC12 as intermediate materials for the expeniment. It was impossible to fabricate a clad material having a clear interface between Al-40%Sn-1%Cu alloy and A1050. However, it was possible to fabricate a clad material having a clear interface between of Al-40%Sn-1%Cu alloy and ADC12. It was found that repeated bending test on the fabricated clad material, there was no peeling. In consequence of line analysis, Sn was not observed on the surface of ADC12.

By applying twin-roll casting as a method for producing thin plate directly from the melt, a vertical type tandem twin roll caster prototype was fabricated. In this equipment, twin roll casters more than two were set at the tandem position. Aluminum alloy three layers clad strip, of which the temperature of the liquidus line of the core strip was lower than that of the overlay strip was fabricated by this caster. As experimental samples, A4045(temperature of the liquidus line:585°C) was used for the core strip and A3003(temperature of the liquidus line:655°C) was used for the overlay strip. In order to prevent melting of the clad strip by solidification latent heat, the core strip and the overlay strip were bonded after cooling the core strip. As a result of cooling the core strip to 530 to 450 °C, Fabrication of the three layers clad strip was possible. In order to investigate the bond strength, cool rolling and bending test was conducted. As a result, The clad strip was not peeled off at the interface.