In this study, porous aluminum core filled in hollow steel pipe composite materials (porous Al core pipe) was fabricated by applying friction welding. Al plates and blowing agent powder were put into the hollow steel pipe, and the rotating tool was pressed into the Al plates. Friction heat was generated and precursor of porous Al was fabricated by mixing Al plates and blowing agent powder by means of plastic flow. Porous core pipe with metal bonding was successfully fabricated by heating the precursor. The compression properties and deformation behavior of porous Al core pipe was obtained by the compression test. As a result, energy absorption per unit of volume of porous Al core pipe increased 1.5 times compare with the hollow pipe. But, the energy absorption per unit mass was slightly decreased.

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Porous Al is superior in lightweight, high sound insulation and high energy absorption. In this study, copper powder dispersed porous Al core filled in hollow pipe composite materials was fabricated by friction welding and in-situ formation of CuAl₂ was attempted for the reinforcement of porous Al. Al hollow disc filled with blowing agent, stabilization agent and Cu powder was put into hollow pipe and the rotating tool was pressed into Al hollow disc. Frictional heat softened Al hollow disc and precursor of porous Al was fabricated because the rotating tool dispersed the powder into Al by means of plastic flow of Al. It was shown that porous Al core filled in hollow pipe composite materials with porosity of approximately 60% and in-situ formation of CuAl₂ was successfully fabricated at a holding temperature of 1003 K and at a holding time of 6 min 30 sec.

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Porous aluminum is a lightweight material with high energy absorption properties. In this study, impact test of A1050-ADC12 functionally graded porous aluminum fabricated by friction stir processing (FSP) route was carried out. It was shown that deformation began from low strength A1050 layer and thereafter high strength ADC12 layer deformed. This result is consistent with the result of static compression test of A1050-ADC12 functionally graded porous aluminum. Consequently, it was shown that A1050-ADC12 functionally graded porous aluminum has the potential for its location of deformation to be controlled.

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Open-cell porous copper (Cu) was fabricated by friction powder compaction (FPC) process, which requires no external heat sources. In this process, a mixture of Cu powder and sodium chloride (NaCl) powder as spacer particle was used as starting materials. The compacting of the powder mixture was conducted only by rotating tool plunged into the mixture. NaCl was removed by placing the sintered mixture in water, and pores were formed. Porous Cu with porosities of 60-80 % was successfully fabricated. In this study, a relationship between leaching time and removal of NaCl were investigated, and pore structures of obtained porous Cu were nondestructively observed by X-ray CT. In addition the compressive properties of obtained porous Cu were investigated.

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Porous aluminum is a multifunctional material with both lightweight and high energy absorption properties. In this study, functionally graded (FG) porous aluminum was fabricated by spacer method varying pore structures. The obtained FG porous aluminum was observed non-destructively by X-ray computed tomography (CT). Image-based finite element (FE) analysis of compression tests of FG porous aluminum using X-ray CT images was conducted. By comparing the results of FE analysis and the deformation behavior of actual compressive tests of FG porous aluminum, it was shown that deformation behavior can be controlled by varying pore structures.

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Porous aluminum is a multifunctional material with lightweight and high energy absorption properties. In this study, A1050-ADC12-A6061 functionally graded (FG) porous aluminum of three layer structure was fabricated by friction stir welding (FSW) route. Pore structure of FG porous aluminum was observed nondestructively by X-ray CT inspection. The compression properties and deformation behavior of FG porous aluminum were obtained by the compression test. It was shown that the fabricated FG porous aluminum compressive test specimen had three different deformation stages and three plateau regions corresponding to the pore structures and types of aluminum alloy.

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Some components of power plant suffer severe abrasion by sliding. Normally, in order to improve abrasion-resistant of the components, alloys with high hardness are welded on the components surface. However, after the welding, the grain size of the welded metal tends to be large, and toughness tends to be low. When the components are required not only high hardness but also high toughness, the grain size of the welded metal should be small.
Considering that the fine microstructure can be formed by applying the HIP coating, we developed a new technology which can form a hard surface layer with higher mechanical properties such as high hardness and high toughness compare with PTA welding layer. As a new coating technology for surface hardening, it is expected to be a more effective technology than that of welding.

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Pure titanium (Ti) powder together with 10, 20 or 30 mass% hydroxiapatite (HAp) was mechanically alloyed (MAed) by using a vibrational ball mill, and the MAed powders were consolidated into bulk materials by spark plasma sintering (SPS). Effects of MA time on hardness and phases of Ti-HAp MAed powders and SPS materials were investigated. Solid-state reactions of the MAed powders and SPS materials were examined by X-ray diffraction (XRD), and mechanical properties of the SPS materials were evaluated by hardness measurements. When the lower amounts of HAp added to Ti, no decomposition of HAp in the MAed powders was observed. However, decomposition of HAp in the MAed Ti-30 HAp powders occurred to form both CaO and CaTiO₃. No effect of MA time on these decomposition processes was observed. Formation of both TiC and CaO was observed in all the SPS materials. The hardness of the MAed powders synthesized with shorter MA time decreased, whereas the hardness increased as increasing MA time. The hardness of the Ti-20 HAp SPS materials fabricated from the MAed powder with shorter periods of MA time exhibited the highest value. The hardness of the SPS materials increased by both an increase in the amount of HAp and in MA time.

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In order to develop high-reliable maintenance systems to secure the structural integrity of reactor components, analytical and diagnostic techniques for the detection of fatigue damage should be developed further. In the present study, crystal orientation analysis and microstructural observation were performed for Type 316 austenitic stainless steel subjected to cyclic loading by electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) to clarify the relationship between the changes in the crystal orientation and the microstructure introduced by fatigue cycles. As a result of the comparison between the EBSD analysis and the TEM observation, it was concluded that the change in the local misorientation identified by the EBSD analysis was due to the formation of the dislocation cell structures identified by the TEM observation.

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Experimental and analytical studies were carried out to clarify servo press slide motion preferable for obtaining uniform cups by one operation of impact extrusion. Cylindrical billets of aluminium (A1070) were extruded into cups by a servo press. The inner and outer diameters were measured along the longitudinal axes. The effects of servo press slide motion on billet temperature were investigated by finite element method. The following results were obtained: 1) Heat generation by processing had a great influence on the accuracy of cup diameters. 2) A constant sliding speed made diameter small at the bottom of cup. 3) By slowing down the slide speed in the middle of the extrusion process, the dimensional accuracy was improved.

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Pure titanium (Ti) powder together with magnesium (Mg) powder was mechanically alloyed (MAed) by using a vibrational ball mill, and the MAed powders were consolidated into bulk materials by spark plasma sintering (SPS). Properties of the MAed powder and bulk materials were evaluated by hardness measurements, X-ray diffraction, optical and scanning microscopy. No solid solution of Mg in Ti was observed during MA process. In addition, no solid-state reaction in the MAed powders and bulk materials was also observed between Mg and Ti under the presence of stearic acid added as the process control agent. As increasing of Mg contents in the Ti matrix, Vickers microhardness of the MAed powders decreased. This phenomenon was also shown to the bulk materials. Applying the MA-SPS process to Ti-Mg system, the level of hardness of the MAed powder and bulk materials can be controlled by the amount of Mg content, MA processing time and sintering temperatures.

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A removal process for the powder compacts prior to sintering (referred to as “green compacts”), which is known as green machining, has been attracting attention lately. In order to clarify the characteristics of green machining, using two types of iron-based powder, we have conducted drilling experiment comparing the green machining and machining the sintered body. Test specimens created under forming pressures of 600 MPa from iron powder and high-strength steel alloy powder were examined for drill tool life, thrust and torque values during drilling, chip morphology, surface roughness and mechanical strength. It is concluded that there is more benefit to be gained by green machining of compacts of high-strength alloy powder than of iron powder.

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To develop the composite journal bearings (CJB) with high strength and high wear resistance, two different mixed powders were compacted in the shape of a double-layers cylinder. A mixed powder of Fe-Cu was used for an outer layer as back-up material. In inner layer, the mixed powder of Fe-Ni-Mo-Cu was used for wear resistance. The compacted cylindrical bearing was sintered at various temperatures. EPMA analysis was conducted to identify the distribution of elemental composition near the interface between the inner and outer layers. As a result, it was confirmed that the joining between the inner and outer layers in the CJB was achieved by a diffusion mechanism and the hardness increased with increasing the sintering temperature. After the sizing process, the CJB became higher circularity than journal bearing made by conventional P/M process.

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A compact, lightweight and flexible artificial muscle has been proposed for use in such wearable rehabilitation devices employing shape memory alloy (SMA) wires. In detail, mechanical performance and an optimal geometric shape as the SMA artificial muscle were investigated experimentally, and discussed using finite element analyses. It was found that the wave shaped SMA wire extended to 25～30% of strain equivalent to the extension of human muscle. The recovery force and the maximum local strain were changed with the geometric shape and the combined structures of SMA wires. The results therefore show that the designed SMA artificial muscle is applicable to wearable rehabilitation device.

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A laser ultrasound generation method using beam equalizer has been developed. A light equalization device in beam condensing unit equalizes beam profile in focused area, even if beam profile of incoming pulsed laser light became worse and not uniform. This device was applied to a non-contact sensing system of crystal grain size of metals. By applying this device, this system can be used stably for a long period. The experimental result shows good correlation between measured Ferrite grain sizes by this system and by the microscope observation. In addition, the measured Ferrite grain size showed good correlation with the tensile test results.

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The mechanical properties of organic field-effect transistors (OFET) fabricated by the thermal press method are evaluated for improving performance of flexible electronic devices. The thermal press method is a novel one to fabricate organic semiconductor devices without any toxic solvents which may cause some problems. In the present study, from the mechanical viewpoints, we have pointed out that the thermal press method has the advantages in forming the OFET with a laminated structure and creating new possibilities for developing a variety of the functional devices. The validity of this perception has been demonstrated by numerical simulations. Based on the present results, the laminated structure of the OFET is effective in not only protecting the semiconductor layer, but also increasing the bending stiffness of the OFET. Moreover, it is shown that the thermal press method has the potential to create various types of OFET to improve the functions of the flexible electronic devices.

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This study was aimed at investigating of Twin roll casting and formability of Al-25%Si alloy strip. Near net shape forming is able to produce that the initial production is very close to the final shape. Near net shape is applied a variety of materials. Twin roll casting process is one of near net shape forming. Hypereutectic Al-Si alloy has some useful advantage low thermal expansion, better thermal conductivity and wear registrant. Recently, the plate of hypereutectic Al-Si alloy which thickness is thinner than 1mm is demanded. The hypereutectic Al-Si alloy is hard and brittle. Therefore, only the many times of hot rolling were useful process to make thin plate. In the present study, the roll casting of Al-25%Si strip was tried by a vertical type high speed twin roll caster from the point of energy saving. The twin roll size of the roll was φ300×W100. Roll-load was set low enough to prevent the sticking of the strip. Casting material was Al-25%Si and Al-25%Si+4%Mg. The roll velocity was 20 m/min. As cast strip of Al-25%Si was 1.6 mm thickness, and Al-25%Si+4%Mg was 2.0 mm thickness. Primary crystal size of as cast Al-25%Si strip was 40-100 μm, as cast Al-25%Si+4%Mg strip was 40 μm. It was able to produce that as rolled strip of 1mm thickness at 1 pass. Primary crystal size of as rolled Al-25%Si strip was 15-40 μm, and as rolled Al-25%Si+4Mg was 15-20 μm.

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This study was aimed that Fabrication of Al/Mg clad material using a horizontal tandem twin roll caster. Magnesium is the lightest of structural metals combining high mechanical strength and low density. However, magnesium is low corrosion resistance. Aluminum alloys and magnesium alloys were fabricated as an Al/Mg composite using aluminum alloys as protective layers, improvement of the corrosion resistance of the magnesium alloys can be expected. In this study using twin roll casting process and downward melt drag process. And also in-line rolling process was used. A horizontal tandem twin roll caster consists of three kind of twin roll. AZ121 was cast by first twin roll, this is first strip. Downward melt drag process was used for casting of A1050, this is second strip. In case of narrow roll gap, AZ121 was melted by A1050 due to increased heat transfer coefficient. In this study, bonding could be better that cladding of aluminum on third twin roll would rather than cladding of aluminum on second twin roll. Thickness of clad strip was 5.5 mm, aluminum layer was 1.1 mm, magnesium layer was 4.3 mm. cladding ratio was 1.1 : 4.3. Mixed layer was 70-90μm in bonding region. Each diffuse layer of Al layer and Mg layer was 10 μm. Primary crystal size of Mg layer was 77μm at mixed layer region, 19μm at center region, 83μm at surface region.

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A high speed twin roll caster is able to cast an aluminum alloy strip directly from a molten metal at high casting speed. However burrs at edges of the cast strip occurred depending on used aluminum alloy. It is the special problem, which a conventional twin roll caster didn't have. Burrs damages side-dam plate used in a high speed twin roll caster. In addition, it may affect down-stream process. We predicted that burrs are rerating to flowability at semi-solidification. In this study, we adjusted side-dam plate lower end position at the casting, and investigated relationship between occurrence position of the burrs and amount of the Si. Additionally, it was added hole drilling for eliminating the burrs. We used AA6061, AC4CH, ADC12, Al-25%Si. As a result, occurrence positions of the burrs were different depending on amount of the Si. The Side-dam plate with the hole was possible to eliminate the burrs.

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A vertical type high speed twin roll caster is able to cast an aluminum alloy strip directly from a molten metal that is poured between the rotating rolls. However defects such as small cracks and unsound thickness distribution of the cast strip occur at faster roll speed. They are related to the contact condition of the roll surface and the melt. In the present study, we used the grooved roll to eliminate the defects, and to save the cost at the same time. We experimented using several grooved rolls with different patterns. When the groove width was 0.45mm; depth 0.2mm; pitch 0.1mm and 1.0mm, stable casting was possible. The shape of bulge was formed on the cast strip surface by the grooved roll. As a result of the color check, the grooved roll could eliminate the small cracks. The surface condition of the strip was more sound using the grooved roll with the pitch of 0.1mm than that of 1.0mm. Stopping the rotated roll during the casting, we observed the contact condition between the melt and the roll, and confirmed how the bulge was formed. To cold-roll for strip with bulges was possible and the bulges was erased. To cast for the sound strip was possible by the vertical type high speed twin roll caster with grooved rolls.

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In this study a consistent projection method for the fluid-structure interaction (FSI) was proposed. The intermediate state variables were used to split the monolithic equation system into the equilibrium equations and the pressure Poisson equation (PPE). The incompressibility constraint is asymptotically satisfied by solving the proposed PPE in the iterative solution procedure under the asymptotic agreement of the intermediate velocity with the velocity. Therefore the proposed method is consistent with the monolithic method. The performance of the present method was demonstrated using a channel, which is one of typical test problems, and a flexible wing flapping in the closed fluid domain with the comparable fluid and structural densities.

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This paper investigates a new constitutive model of the competitive swimwear considering stress-softening. The purpose of this study is establishment of an engineering technique using numerical analysis to make the design for swimwear more effective. Effective design considering mechanical characteristics would be an advantage in swimming competitions. The fabrics for competitive swimwear show nonlinear elasticity regarded as hyperelasticity and they have an anisotropic characteristic which is dependent on the directions of warp and weft yarn. In order to reproduce these properties numerically, hyperelastic model considering anisotropy was produced. In addition, the fabrics present a loss of stiffness after first loading of cycle loading test. This phenomenon depended on the maximum deformation previously reached in the history of the material. To account for the stress-softening property, a stress-softening model using stiffness ratio of warp or weft was proposed. Then, cyclic loading tests were conducted and the applicability of the model was verified.

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Engineering plastics provide superior performance to ordinary plastics for a wide range of the use. For polymer materials, dynamic stress and strain rate are major factors to be considered when the strength is evaluated. Recently, high speed tensile test is recognized as a standard testing method to confirm the strength under dynamic loads, and it is analyzed by the finite element method; then, the maximum dynamic stress and strain rate are discussed with varying both the tensile speed and the maximum forced displacement. The strain rate concentration factor is found to be constant independent of the tensile speed, which is defined as the maximum strain rate appears at the notch root over the average nominal strain rate at the minimum section. The maximum strain rate is controlled by the tensile speed alone independent of the magnitude of the forced displacement. It is found that the difference between static and dynamic maximum stress concentrations (σ_max -σ_st ) at the notch root is proportional to the tensile speed when u/t≦5000mm/s.

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We report the effects of surface damage and crystal orientation on fracture strength of single crystal silicon (SCS) by means of tensile test using electrostatic-force grip. The specimens of three major crystal orientations fabricated from (110) SOI wafer were characterized with different surface morphologies prepared by the specimen patterning process. Our specimen patterning process was composed of Bosch process and wet etching process for surface residue removal. We changed processing time and sequence of the two processes to get different surface morphologies. As result of uni-axial tensile test of 9 types of specimens (length: 120 μm, width: 5 μm, thickness: 5 μm), i.e. specimens of 3 crystal orientations with 3 different surface morphologies, improvement of surface morphology doubled average tensile strength: e.g. <110> strength varied from 1.8 GPa to 3.6 GPa, while average tensile strength difference among crystal orientations was less than 20 % on each fabrication conditions. The fracture surfaces mainly consisted of (111) plane. We found tensile fracture characteristics of 3 crystal orientations: in <100> specimens the fracture origin location changed by the fabrication conditions, while <110> and <111> specimens respectively showed quantitative relationships between surface morphology and tensile strength common to different fabrication conditions. These results are beneficial for tensile strength prediction from surface morphology.

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Long-term measurement and prediction for Ti-6Al-4V and A286 bolts was conducted. It was pointed out that Ti-6Al-4V indicates significant creep behavior and accumulated large creep strain and thus Ti-6Al-4V can not be applied for preloaded bolts. In addition, preload relaxation due to creep of solid-film lubricants for bolts and fastened aluminum parts were also pointed out. Recently, the authors developed a high strength bolted fastening system for satellite structures with PTFE (polytetrafluoroethylene) solid film lubricated Ti-6Al-4V bolts and aluminum threadedand drilled-hole parts. The authors, hence, measured the preload of the fastening system for 253-days, predicted 30-years later preload, and confirmed that the preload reduction was not harmful.

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The elastic-plastic fracture toughness, J_Ic, of SM490B carbon steel plate was investigated in air and 0.7 MPa hydrogen gas. J_Ic tests were conducted in accordance with the JSME standard, JSME S001 (1981). J_Ic was much smaller in hydrogen at a displacement velocity of V = 2 × 10^-3 mm/s (J_Ic = 10.0 kJ/m²) than in air at V = 2 × 10^-3 mm/s (J_Ic = 248.6 kJ/m²). J_Ic in air does not satisfy the validity requirement. In hydrogen, surprisingly, a further decrease in V did not decrease J_Ic, but increased it. J_Ic in hydrogen at V = 2 × 10^-5 mm/s was 60.9 kJ/m². The large and small values of J_Ic in air and hydrogen corresponded to the fracture morphology. In air at V = 2 × 10^-3 mm/s, a critical stretched zone, SZW_c, was formed at the tip of the fatigue pre-crack, followed by dimples. In hydrogen at V = 2 × 10^-3 mm/s, quasi-cleavage instead of SZW_c and dimples were formed at the pre-crack tip. In hydrogen at V = 2 × 10^-5 mm/s, SZW_c was formed at the pre-crack tip, followed by dimples again. This elastic-plastic fracture toughness behavior was analyzed assuming HESFCG (hydrogen-enhanced successive fatigue crack growth), which is proposed by the authors to explain the acceleration of fatigue crack growth rate in the presence of hydrogen. The elastic plastic fracture toughness test shown in 0.7 MPa hydrogen gas at V = 2 × 10^-3 mm/s 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 in 0.7 MPa hydrogen gas at V = 2 × 10^-3 mm/s is not the real elastic-plastic fracture toughness. We conclude that the real elastic-plastic fracture toughness in 0.7 MPa hydrogen gas can be determined by fracture toughness testing in 0.7 MPa hydrogen gas at V = 2 × 10^-5 mm/s.

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A low-carbon steel bar with an ultrafine elongated grain (UFEG) structure and an ultrafine exiaxed grain (UFG) structure was fabricated by multipass caliber rolling at 500°C and subsequent annealing at 500, 550, 600 and 650°C. The Charpy impact and static tensile tests were conductued at ambient temperature. The microstructures in the as-rolled bar and the annealed bars until 600°C consisted of an UFEG structure with a strong α-fiber texture. The both strength and impact energy increased in the as-rolled bar consisting of spheroidal cementite particles that distributed uniformly in the elongated ferrite matrix of transverse grain size of 0.73 μm. In the bars with the UFEG structure, many microcracks during an impact tests were observed near the main crack with fine dimples, and they were classified into two types: one normal to the striking direction (SD) and one with an angle of 45° to the SD. The occurrence of such brunching cracks corresponded to the spatial distribution of {100} cleavage planes and boundaries of the elongated grains. This tendency disappeared as annealing temperatures increased. The as-rolled bar exhibited the best strength-toughness balance in the annealed bars, conventional carbon steels and some UFG steels. In conclusion, the strength-toughness balance is improved by refining crystal grains and controlling their shape and orientation.

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In recent years, polymer nanocomposite that is composed of polymer and nano scale filler is getting much attention. The clay, which is a layer compound, is mainly used as filler. One of the most common mixing methods is melt-compounding. A twin-screw extruder is usually used to compound the melted polymer and clay. However, it is difficult to discuss the effective compounding method for exfoliation and dispersion of clay in the polymer because shear stress and flow direction around screws are extremely complex. Therefore, physical factors of clay exfoliation have been not known. From the above reason, the purposes of this research are to clarify the factors for making clay exfoliated to a single layer and to acquire the guideline for optimizing mixing conditions using high speed flow in narrow tube that can give simple high shear stress to the resin. TEM observation and rheological analysis were conducted to quantify the exfoliation state of clay. It was verified that the specific energy was the most important parameter for the exfoliation of clay platelet.

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In this paper, we derive a general solution for an isotropic elastic medium (matrix) with nonconcentric multilayered circular inclusions. Inner inclusion is perfectly bonded to the outer inclusion. Matrix is infinite extent under anti-plane deformation. These inclusions have different elastic moduli, radii and central points. The matrix is subjected to arbitrary loading, for examples, by uniform anti-plane shear stresses at infinity, as well as a concentrated force , screw dislocation , uniform distributed line load at an arbitrary point. The solution is obtained through iterations of the Möbius transformation as a series with an explicit general term involving the complex potential of the corresponding homogeneous problems. The procedure is referred to as heterogenization. Using these solutions, several numerical examples are presented graphically.

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It is indispensable to estimate welding residual stresses for assurance of structural integrity in welded structures. In order to asses a crack growth rate of an observed crack in weld zone, three-dimensional distribution of welding residual stress for whole structure have to be evaluated quantitatively, however it is impossible to estimate stress gradient in the thickness direction by conventional methods such as X-ray diffraction and the ultrasonic method. To make things worse, the estimated stresses by these methods can not be input to the FEM (Finite Element Method) model that has been used at design time for the assessment of the structural integrity. Then the eigen-strain method has been proposed. In this method, three-dimensional welding residual stresses are calculated by an elastic FEM analysis from eigen-strains those can be evaluated quantitatively by the inverse analysis from released strains measured by strain gauges while the geometric boundary condition or material properties of the object has been changed. However, inelastic strains are newly created during machining or heating, the estimation accuracy of this method becomes poor because in the eigen-strain method, the eigen-strains before and after measurements have to be the same. In this study, a calculation technique to evaluate eigen-strains included processing strains in removal process is shown, and effectiveness of this method is demonstrated numerically in the bead flush method. As a result, three-dimensional welding residual stresses for whole region were estimated accurately even if higher values of processing strain were added in the removal process.

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Recently, it has been reported that the primary water stress corrosion cracking (PWSCC) has occurred in nickel based alloy weld components such as steam generator safe end weld, reactor vessel safe end weld, and so on, in PWR. Defect detection and sizing are important in order to ensure the reliable operation and life extension of nuclear power plants. In the reactor vessel safe end weld, it was impossible to measure crack depth of PWSCC. The cracks have occurred in the axial direction of the safe end weld. Furthermore, the cracks had some features such as deep, large aspect ratio (ratio of crack depth and length), sharp geometry of crack tip, and so on. Therefore, development and improvement of defect depth sizing capabilities by ultrasonic testing (UT) have been required. Phased array UT technique was applied with regard to defect depth sizing at the inside inspection in Ni-based alloy welds. Phased array UT was examined a standard block specimen with side drilled holes (SDHs). From the experimental results, the performance of linear array probes and dual matrix array probe were investigated. In the basis of the results, UT procedure for defect depth sizing was investigated and proposed. The UT procedure was applied to the defect depth measurement in Ni-based alloy weld specimen with electric discharge machine (EDM) notches. From these results, good accuracy of defect depth sizing by phased array UT for the inside inspection was shown. Therefore, it was clarified the effectiveness of the UT procedure for defect depth sizing in Ni-based alloy weld.

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In this study a finite element analysis using hierarchal decompositions for the interaction of structural, fluidic and electrostatic fields is applied for vibration analyses of a MEMS structural component. The interaction is partitioned into the electrostatic field and the fluid-structure interaction (FSI) using the block Gauss-Seidel method. The FSI is split into the pressure field and the other using a projection method, where the intermediate state variables are used for the splitting without generating computationally expensive Schur complement matrices. The developed finite element analysis is applied for a micro cantilever beam actuated by the step electrostatic force in vacuum and air. It was demonstrated from the comparisons among the numerical and experimental results that the proposed analyses provide the results consistent with the experimental results. It follows from the present results that the numerical analyses taking into account the interaction of the structural, fluidic and electrostatic fields are required for the accurate predictions of the vibration characteristics of the MEMS structural components.

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Low cycle fatigue tests and finite element analysis were conducted using 100A elbow specimens made of STPT 410 steel with local wall thinning in order to investigate the influences of local wall thinning on the low cycle fatigue behavior of elbows with internal pressure. Local wall thinning was machined on the inside of the elbow and was prepared at extrados, crown and intrados. The parameters of the wall thinning were same (eroded ratio=0.5, eroded angle=180 degrees and eroded length=100mm) in the all test cases. The elbow specimens were subjected to the prescribed cyclic in-plane bending displacement with constant internal pressure of 0 to 12 MPa. Also, low cycle fatigue tests using sound elbows were carried out for comparison. Low cycle fatigue life of wall thinned elbows was not so different regardless of location of wall thinning. Low cycle fatigue strength of the elbow specimens were beneath the best fit fatigue curve and its reason can be explained by combining the equivalent strain range and cumulated damage theory, considering reduction of ductility under multi-axial stress state.

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Unstable behaviors of thin-shell structured columns under axial compression displayed the large loading rate dependence markedly, which can be well resolved by considering the effect of inertial force in the high loading rate region, and by von Karman's effective width solution in the low loading rate region (see Ref. (2)). This paper focused on clarification of mechanism of the transition between a low loading rate region (named as region A) to a high loading rate region (region C) via a transition region (region B) by changing their shapes parametrically. It was observed that the maximum reaction force of region A strongly depends on only the width of column, not on the length. In the case of small width, the maximum reactions are prescribed by the uniformly yielding state and by the Euler buckling. As the larger width, they varied between two Karman's solutions with κ=1.7 and 4.0. These results were successfully summarized by the proposed modified Karman's effective width. On the other hand, the maximum reaction force has an explicit length dependence in the region B. When its length becomes longer, region B shifts to the higher loading rate area. The reason of this shift is caused by the nonuniform stress distribution during the repeated stress wave propagation.

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As a result of the 2011 Great East Japan Earthquake, a severe fire and explosion accident of spherical tanks for LPG(Liquefied Petroleum Gas)storage occurred at Chiba. The leakage of LPG from the piping was caused by overturn of one of tanks and resulted in fire. Following ductile fracture of steel pipe braces, tank supports collapsed by buckling and the tank overturned by the seismic force. In this study, fracture mechanism of the steel pipe braces is made clear and an inspection of the mechanism is performed by the detailed stress analysis. Finally the present design code for seismic endurance is discussed.

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