In this study, we discussed about the effect of film thickness on bending deformation of coated nanowire (NW). The three dimensional theoretical model for analyzing the effect was proposed in this paper. The dependence of the misfit strain on the film thickness was introduced in the model. We concluded that bending direction of the NW varied with increasing the coating film thickness. This result arises from the dependence of the misfit strain on the film thickness and the nonuniform film thickness along the circumference of the NW.

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Recently, it has been reported that the microwave gives an effect to an interatomic force in local area among materials. Therefore, it is thought that an identification of materials and an evaluation of electrical characteristics become possible by clarifying the relation between microwave and interatomic force. So, we investigated interatomic force under the tip of microwave-AFM probe by focusing on the force-distance curve measurement using microwave-AFM as the first step. This paper describes the method and the results of the force-distance curve measurement on the sample of Au, Si, and glass. Results of this experiment indicate actually that microwave works as a force that amplifies the attractive force and the effect of microwave is different among samples which have different electric conductivities.

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Sn thin film is expected to be an ideal material for anode of lithium-ion batteries (LIB) because it has higher capacity than carbon conventionally used. However, the volume change during charge and discharge results in fracture and pulverization of anode, which lead to the degradation of the cycle properties of LIB. Therefore, we aimed at improving the cycle performance by controlling the structure of Sn thin film. Here, by modulating the sputtering conditions, two type of Sn thin films with different structures were prepared to make coin-type half-cells as anode. The results of the initial cycle indicate that the capacity of Sn thin film anode can be improved by creating island structure.

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Multiwalled carbon nanotubes in uncured ultraviolet ray curing resin suspension were aligned by applying the multi-phase voltage. After the alignment, the suspension was cured by irradiating ultraviolet ray. The multiple-electrode used to the experiment was constructed by 24 long and slender electrodes. The cover glass was put on the multiple-electrode, and the suspension was dropped on the cover glass. The multi-phase voltage was applied to the multiple-electrode, and the traveling electric field was applied to the suspension.

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Multi-walled carbon nanotubes (MWCNTs) are highly resistant to deformation, and their electrical characteristics are resistant to degradation by ambient conditions. The damage mechanisms of CNT are considered to be the oxidation by Joule heating and migration of carbon atoms by high-density electron flows. In this study, we investigated the damage mechanism of MWCNT structures used as nano-component of electronic devices. A high current density testing system was applied to the micro meter-sized line constructed by MWCNT network. The MWCNT line of 30 μm width and 800 μm length was fabricated. Initially the electric resistance of MWCNT wires decreased in the DC loading. And the resistance began to increase after 10h under the condition of initial voltage of 4V applied. The open circuit was occurred at 55h passed under the condition.

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In order to incorporate the Ag nanowire meshes into the opto-electronic devices as TCE, it is important to investigate their reliability. It is well known that the corrosion of Ag is a common phenomenon, which will decrease the cross-sectional area of Ag nanowire, and may degrade the Ag nanowire mesh. Therefore the aim of present work is to investigate the effect of corrosion on the electrical breakdown of an Ag nanowire mesh. Firstly, the numerical analysis on the melting behavior of an Ag nanowire mesh was conducted. Secondly, by utilizing the figure of merit, the current-carrying capacity of the Ag nanowire mesh subjected to corrosion was calculated by simple conversion. It shows that the current-carrying capacity is decreased with the decrease of cross-sectional area of Ag nanowire caused by the corrosion. Moreover, the lifetime of the Ag nanowire mesh subjected to corrosion stressed with current was predicted.

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In this report, surface morphologies modification and tensile strength improvement of single crystal silicon (SCS) microstructures using KrF excimer laser (248 nm) are presented. The sidewall roughness of dry-etched SCS beams was laser-treated by tilting the specimen. Harsh (〜4 J/cm^2) irradiation was successful due to localized annealing for free standing structures. The annealing was conducted on the tensile test samples of 120 μm long, 5 μm wide and thick. The averaged tensile strength of the laser-treated samples increased by 20 % compare to the as-fabricate samples. The sidewalls were smoothened and cross-sections were rounded by laser-annealing, which contributed for the improvement of tensile strength.

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A simple mechanical damage testing method, combined with Acoustic Emission (AE) monitoring was developed in order to investigate the mechanical performance of solid state electrochemical devices under operating conditions. The damage testing method was applied to solid oxide fuel cells and lithium ion batteries. The damage process was shown to involve cracking in the electrode and electrolyte, and the fracture damage was most likely due to chemical expansion-induced stresses. It was demonstrated that the AE method enabled us to detect the above-mentioned damage process and to determine the condition for the onset of the damage in the newly electrochemical devices.

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Electrolyte membranes are chemically degraded by H_2O_2 which are created during operation of the polymer electrolyte fuel cell (PEFC). In this study, the correlation between the mechanical properties and the chemical degradation of the electrolyte membrane for PEFC was investigated. In order to investigate the mechanical properties of these films, tensile test was carried out in ambient air. Also hardness test was carried out by the means of the nano-indenter at the surface and/or cross section of membrane. As a result, the tensile properties decreased, and also hardness increased as exposure time increased. This result means that the mechanical properties and the chemical degradation are high correlative. Therefore the chemical degradation can be estimated by means of mechanical properties.

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We have attempted to construct multiscale model which can simulate inelastic deformation and stress state under operating conditions. It would need to the information about mechanical properties of solid oxide fuel cell constituent materials under operating condition for analysis model building up process and simulation indeed. Therefore, mechanical property of Ni-YSZ and yttria stabilized zirconia, used as SOFC common materials are evaluated under simulated operating condition by developed In-situ mechanical testing machine. From experimental result, Ni-YSZ composite has showed that ductile-like deformation was induced under 800℃/H_2 condition for the Ni contents of 30 and 50 vol. % from the SP tests, and creep behavior is due to its ductility from creep tests. On the other hand, 8YSZ has showed creep rupture propagation guessed crack growth under air/850℃ condition.

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Ba_<0.5>Sr_<0.5>Co_<0.8>Fe_<0.2>O_<3-δ>(BSCF) has emerged to be a promising candidate as cathode for solid oxide fuel cells (SOFCs) and as oxygen separation membrane because of its high electronic and ionic conductivity. On the other hand, an anomaly in mechanical behavior around room temperature has been pointed out. The present study investigated the mechanical behavior of BSCF at room temperature. An unusual strain oscillation was observed in the temperature range from 273 K to 303K. Elastic modulus significantly decreased from 80GPa to 60GPa over the room temperature. The linear expansion coefficient peaked at 17μK^<-1> around 350K.

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Temperature and frequency dependence of Young's modulus and internal friction of La_<0.6>Sr_<0.4>Co_<0.2>Fe_<0.8>O_<3-δ> were evaluated by dynamic mechanical analysis. A relaxation peak in the internal friction which follows a significant decrease in the Young's modulus was observed. It was suggested that the peak was derived from domain reorientations. An introduction of oxygen vacancies into the sample significantly changed the temperature dependence of the Young's modulus and the internal friction. The Young's modulus became larger especially below 400 K. A small peak which depended on the oxygen vacancy concentration was observed when the oxygen vacancies were introduced. This peak was considered to be due to oxygen vacancy diffusion. Such significant changes in the temperature dependence of the Young's modulus and the internal friction may be caused by crystal structure change and pinning of domain walls by the oxygen vacancies.

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For attractive mixed ion-electronic conduction properties and also magnetic properties, lanthanum cobalt oxides are expected to be applied in various fields, such as cathode of solid oxide fuel cells, oxygen separation membrane, and magnetic material. With regard to mechanical properties, anomalous behavior around room temperature, known as fentelasticity, has been reported in recent years. In the present study, we conducted uniaxial compression tests of La_<0.6>Sr_<0.4>Co_<0.8>Fe_<0.2>O_<3-δ> (LSCF) in the temperature range from 83 K to 543 K. The results demonstrated that LCO and LSCF exhibit ferroelastic behavior all the temperatures. The variation of the stress-strain curve with temperature was greater for LSCF than for LCO. The elastic modulus of LSCF slightly increases from 83 K to 273 K but drastically decreased around 273 K, which was higher than the one of LCO in the whole temperature range.

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La_<0.58>Sr_<0.4>Co_<0.2>Fe_<0.8>O_<3-δ> (LSCF) has emerged to be a promising candidate as cathode for solid oxide fuel cells (SOFCs) and as oxygen separation membrane because of its oxygen ion conductivity; however, it has been reported that performance degradation can be caused by Sr segregated on surface of LSCF during practical operation at elevated temperature. The present study investigated the Sr surface segregation in LSCF annealed under uniaxial compression. The surface segregation of Sr-rich phase was observed, especially on the grain boundaries. The size of the segregation particle increases with increasing the annealing time, whereas its number has no clear dependence on the annealing time. The particle size is larger but the number is smaller in the sample annealed under compression than in the one annealed without compression, which could be attributed to grain-boundary sliding and stress-enhanced Sr-diffusion aiding high-temperature creep deformation.

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We employ molecular dynamics simulations to study oxygen ion diffusion in surface area of yttria-stabilized zirconia (YSZ). Interatomic potential that we developed and used in this study is based on dipole model. Applicability of the potential to simulation of YSZ surfaces was proved by reproducing surface energies and structures. Oxygen vacancy depletion is observed near (111)YSZ surface, which decreases local diffusion near the surface. In contrast, vacancies tend to segregate at (110) surface increasing local surface oxygen diffusion.

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Composite sintering is one of the critical fabrication processes deeply related with an initial performance of solid oxide fuel cells (SOFCs). However, the quantitative understanding of composite sintering is still lacking due to its inherent complexities linking with multiple mechanisms. In this study, the microstructural trajectories of NiO-YSZ during the composite sintering were quantitatively measured utilizing three dimensional reconstruction approach based on focused ion beam-scanning electron microscopy (FIB-SEM) technique. This approach allows us to estimate the change of grain size and tortuosity factor of two phases as a function of relative density. The critical transition of grain growth is observed around the relative density of 0.9, in accordance with the pore network change.

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To predict the long-term durability of solid oxide fuel cell (SOFC) anode, it is important to determine the surface diffusion coefficient of Ni. Although the effect of surface adsorbed species on surface diffusion is well known by both experimental and theoretical work, the available data for Ni surface diffusion assuming SOFC operating condition is not sufficient to simulate microstructural evolution. To understand the effect of surface adsorbed species on surface diffusion, it is important to identify the stable movable species on the surface. Therefore, we calculated the formation energy of Ni_nX_m cluster (X=H, O, and S) on Ni(111) surface by using density functional theory (DFT) calculation. In this study, the contribution of surface adsorbates to cluster formation energy is calculated by using energy gain of surface adsorbates by attaching to form cluster as a reference to binding energy on clean surface. From our calculation results, it is found that Ni_3S_3 cluster could be promising stable cluster and this is in agreement with experimental observation. For hydrogen NiH could be dominant cluster, while for oxygen NiO or Ni_3O are favorable on the Ni(111) surface. To analyze the detailed effect of surface adsorbed species on the Ni surface, we have to perform more precise calculation and to consider the temperature effect s.

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An initial performance of solid oxide fuel cell deeply correlates with a composite sintering process during anode fabrication. In this study, we develop a three-dimensional kinetic Monte Carlo (KMC) code based on a q-state Potts model in order to numerically predict a microstructural evolution during NiO-YSZ composite sintering. Our simulations successfully predict the grain size-density trajectories and the tortuosity factor evolution during sintering that well match with our experimental measurements using a three-dimensional FIB-SEM tomography.

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Ba_<0.58>Sr_<0.4>Co_<0.2>Fe_<0.8>O_<3-δ> (BSCF) has been developed as oxygen separation membrane because of its high electronic and ionic conductivity. I BSCF membrane in service could be subjected to thermal and chemical stresses due to gradient of oxygen partial pressure and temperature through the membrane. Therefore, the stress effect on the separation performance has been an issue of concern. In this study, we investigate d the electrical conductivity of BSCF under compressive loadings at various temperatures. It was found that the electrical conductivity increases with increasing the stress, which can be attributed to piezoresistivity. The piezoresistive effect at room temperature was smaller (〜0.6%) than compared to the ones at the elevated temperatures (〜1.5%), which might be related to the the elastic modulus.

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Lattice volume of solid state ionic conductors was closely related to its electrical properties, because oxygen ion, proton and other ionic carriers migrate via hopping between sights in lattice. Therefore, in the case of conventional developing of ionic conductors, i.e. doping different valent element, lattice volume change caused by doping had been discussed. In this study, we attempted the effect of outer forces to lattice volume and its influence to electrical properties. Yttrium stabilized zirconia was adopted to be objective materials, because it is most popular electrolyte material for SOFCs. Single crystalline pellets of YSZ were fitted into the basement made of Al_2O_3 and Si_3N_4 at room temperature, and annealed. Compressive outer forces was applied in axial directions because thermal expansion coefficient is differ between YSZ (10.3×10^<-6> K^<-1>), Al_2O_3 (7.7×10^<-6> K^<-1>) and Si_3N_4 (3.2×10^<-6> K^<-1>). The applied forces reached to 800 MPa at 800 oC with the Si_3N_4 basement. Electrical conductivity of YSZ pellets was measured in vertical direction to stress plane, and the influence of lattice modulation was discussed.

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An experimental method was developed in order to evaluate the mixed mode (I+II) impact fracture toughness for CFRP (Carbon Fiber Reinforced Plastic) adhesive joints using ramped incident wave. The MMF (Mixed Mode Flexure) specimen was employed for the evaluation of energy release rate. The dynamic response of the specimen was studied on the basis of computational results using finite element method. In the impact fracture toughness test, the SHPB (Split Hopkinson Pressure Bar) system was used for studying the dynamic response of the specimen. When a slow gradient ramped incident stress wave was applied to the specimen, bending vibration of the specimen was suppressed, and consequently dynamic energy release rate could be evaluated more precisely. Energy release rate could be estimated more precisely with the formula based on the surface strain of the specimen, whereas vibration was overestimated with the formula based on reaction force at loading point.

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In this study, the tensile properties of the quasi-static and the impact tests for 7075 aluminum alloys subjected to pre-fatigue deformation in a humid environment were investigated. An impact tensile test was performed by means of the Split Hopkinson pressure bar method. The flow stress in both the quasi-static and the impact tests was unaffected by the pre-fatigue deformation. On the other hand, it was clarified that the ductility of the pre-fatigue specimen was slightly lower than that of the non-fatigue specimen. The ductility of the quasi-static test was decreased as compared with the impact test. It is thought that the ductility loss occurred due to changes in the microstructure, such as dislocations caused by the presence of hydrogen in the specimen due to pre-fatigue deformation in a high-humidity environment.

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Crushing compression test of sand has been done under static loading conditions in the fields of geotechnology. However, measurement method of experiment has not been established at high speed impact due to the various parameters of sand (grain diameter, density, material, moisture content) which make it more complicated. The development and performance evaluation of projectile accelerator for high speed experiment had been performed for the study of crushing phenomenon of the sand. The diaphragmless vertical gas gun do not use the diaphragm that will affect the experiment had been developed and is able to handle target material with fluidity.

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The impact strength of adhesively bonded joints was investigated at a low temperature. Tubular but joint specimens consisting of stainless steel were utilized for the test and loaded with a biaxial testing machine by which a combined loading can be applied to the specimens. The specimens were cooled with vapor of liquid nitrogen and the tests were canied out at -40 C. The impact strength increased with respect to loading rates at room temperature in all the radial direction of loading directions. However, the strength remained unchanged at -40 C even in high rate loading conditions.

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Occurrence of reflected wave in Split Hopkinson Pressure Bar (SHPB) method had caused the limitation of deformation time, which is considered to be insufficient for the high-strain foam material. A new device has been proposed for foam material as an alternative to SHPB method. This device has a small detection part designed for the reflected wave to be very small and negligible by creating a big surface area ratio at the detected section and stress transmitted bar. Besides, the ability to detect small strain had been improved due to the small thickness of the device's neck part. We found that an unexpected vibration had appeared in the detection part due to the small thickness of the neck which will influence the data obtained during the impact compression. As a countermeasure, we study the optimum size of detection part by numerical analysis of two different sizes. The comparison of the numerical analysis showed that the shorter neck's length is better for vibration suppression. We did quasi-static and impact load experiments and compared the two.

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Polypropylene (PP)/aramid fiber (AF) and PP/AF/calcium carbonate (CaCO_3) composites were fabricated by melt-mixing process using a single screw extruder. Dumbbell shaped specimens were also fabricated from these mixture by injection molding process. Tensile and three-point bending tests were conducted using these specimens, and obtained results were compared for discussion of effect of CaCO_3 particle dispersion on the mechanical properties of PP/AF composite. Results show that tensile strength and modulus were improved by AF compounding. CaCO_3 particle dispersion effect was observed at tensile modulus of PP/AF/CaCO_3 with 0.15μm diameter.

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Flexible tubes are mechanical devices for absorbing energy or displacement in structures. They are widely used as expansion joints to ease thermal expansion, vibration, axial displacement and so on. Most of them consist of tubular bellows made of stainless steel with covering braids. In the present study, the characteristics of deformation and stress in a-shaped and U-shaped stainless bellows generated by internal pressure and axial loads are examined by numerical analysese.

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Hyperelastic Ogden Model is commonly used to perform a finite element analysis of large deformation materials, e.g. rubber. To properly identify the parameter value of Ogden Model, not only simple tensile but also planar tensile and equibiaxial tensile test are required. In equibiaxial tensile test, a cruciform specimen is actually used. However, a stress concentration at the corner area of cruciform specimen causes an early rupture, resulting to a difficulty on obtaining mechanical response of the material at large strain condition. In this study, finite element analysis and equibiaxial tensile test using a simple fixture developed by the authors, were conducted to investigate the stress distribution and the stress-strain relationship during equibiaxial tensile loading of cruciform specimen with different corner designs. This study provided new insight into optimum shape of the corner of cruciform specimen.

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A gas gun generates a high-speed projectile, and is used for a high-speed impact experiment. Since the tear gas gun not using powder has easy operation, it is used for many impact experiments. At this laboratory, the gas gun is developed, various projectile are accelerated and the impact experiment is conducted. There is a requirement which fires a big projectile and the launching tube of a 20mm caliber was changed into a 50mm caliber. The result is reported. Moreover, the impact test to Space Equipment was conducted as an example of use of a gas gun, and the measurement impact acceleration and Shock Response Spectrum was reported.

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The ultrasonic propagation behavior of CFRP laminates immersed in water at oblique incidence is studied theoretically by using the stiffness-matrix method. Spring-type interlayer interfaces are employed to take account of the influence of interlayer resin-rich regions, and the dependence of the amplitude transmission coefficient on the interlayer interfacial stiffness, frequency, and the angle of incidence is investigated. The dispersion relation for an infinite layered structure is calculated by the Bloch's theorem, and it is shown that the band-gap is closely connected with the frequency range where the transmission coefficient of the finite layered structure becomes almost zero. Comparing with the experimental transmission coefficients for an 11-layered CFRP laminate, the theoretical results are verified.

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Strain rate reduction tests are made on high purity iron containing of 14ppm C, S20C and S45C at very high strain rates. In order to evaluate quantitatively the strain rate dependence of the dynamic flow stress at each strain rate, decrement strain rate tests are performed at strain of about 0.20 at the strain rates above about 1 × 10^4/sec. The reduction ratios caused by the collision between an impact bar and decelerators are 0.44 and 0.586 of the strain rate before reduction. Activation volumes are determined from the amounts of the flow stress drop obtained from the reduction tests and the relation of a thermal activation process. The magnitude of activation volumes determined for the given materials depends not only on the strain rate but also on the difference in the carbon contents.

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A test method for interlaminar toughened thick CFRP laminates in the out-of-plane direction was studied. Unidirectional thick CFRP laminates whose thickness is approximately 17 mm were used in this study. Spool specimens machined from that thick laminates were loaded in the out-of-plane direction. Metal tabs were bonded to upper - and - lower surfaces of a specimen. At the bonding process, an alignment fixture was used to enhance alignment precision. In addition, an axis adjuster using wood's metal was used to connect the specimen with a testing machine with high axial precision during the tests. As a result of static test, it was confirmed that tensile and compressive load were applied without bending deformation. As a result of fatigue test, it was confirmed that the fatigue life at stress ratio of R=-1 is shorter than that at R=0.1.

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Numerical simulation of electromagnetic flux compression using electromagnetic forming analysis is presented where thermal-electromagnetic-structural coupling analysis is considered using a finite element analysis commercial code. The electromagnetic flux compression system mainly consists of two parts, inner and outer copper coils. It is found that deformation of the inner coil due to Lorentz force is successfully simulated. The technique used in this study can be helpful in determining optimal coil parameters of the system to obtain good qualitative electromagnetic flux.

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A room temperature bonding technique namely Surface Activation Bonding (SAB) has studied on micro bonding application. In this technique, a stable oxide layer exists on a material surface is physically removed by Fast Atom Beam (FAB) irradiation in Ultra High Vacuum chamber, and then the bonding is accomplished by an atomic-order contact between two activated surfaces. In this study disscussed the posibility of lower cacuum conditino SAB process for large-scale structual materials. The SAB bonding tests using five kinds of nano-scale roughness mirror polished metals (Al, Fe, Ni, Zn and Cu). As the result, it was clarified that lower oxide formation and higher diffusion materials, Cu and Zn had good bondabilities. This result indicates that oxidation and diffusion are important factors of the bulk SAB. Moreover, the influence of exposure during SAB process was disscused. The bonding was successful up to 45 Pa・s exposured. This can be understood the bonding might be possible under lower vacuum condition. The possibility of the room temperature bonding for bulk structural materials was indicated.

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Fiber reinforced plastics is increasingly used to improve fuel efficiency and motion performance of vehicles by weight reduction. Especially, short fiber reinforced thermoplastics is expected to expand its demand because of its superior moldability, productivity, and recyclability. In this study, influences of glass fiber diameter and cross sectional shape on the impact properties of short glass fiber reinforced polyamide were investigated using split Hopkinson pressure bar. In the tensile test, specimen with smaller fiber diameter showed higher tensile strength. Glass fiber reinforced polyamide with flat glass fiber also showed higher strength than that with normal glass fiber. On the other hand, a significant influence of fiber diameter and cross sectional shape on mechanical properties was not found in the compressive test. As a result of the fracture surface observation using scanning electron microscope and the average fiber length measurement, it was revealed that interfacial fracture was a dominant fracture mechanism under tensile loading whereas matrix fracture was dominant under compressive loading. Consequently, the influence of fiber diameter and cross sectional shape on impact properties was different under compressive and tensile loading.

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In the event of a level crossing accident, train passengers sitting on seats have a risk of getting injured in collision with seats in front of them. In order to evaluate the passenger's injury quantitatively, we need to grasp physical properties of the seat in terms of dynamic strength. We carried out dynamic tests by striking seats with an impactor and FE analyses under the same condition as the tests. The numerical results obtained by FE analyses were generally consistent with the empirical results in terms of the load-time characteristics as well as the deformation of seats.

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This paper reports the preliminarily experimental results of shock wave propagation visualization by hypervelocity impact. An experimental investigation of hypervelocity impact was performed by using a ballistic range at Institute of Fluid Science, Tohoku University. The process of shock wave propagation by hypervelocity impact was visualized by shadowgraph method and recorded by high-speed video camera.

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As one of advanced functional materials, Shape Memory Polymer was studied on the shape recovery property, the shape fix property, and so on. However, it is difficult to comprehend the simple shape recovery behavior, because the viscoelastic and shape recover behaviors will occur simultaneously. Viscoelastic behavior is based on the entanglement effect on their polymeric chain, and the shape recovery behavior is based on the cross-link behavior. It is, therefore, necessary to divide these effects for understanding the viscoelastic and shape recovery behavior. The goal of this paper is to understand the viscoelastic and the simple shape recovery behavior, which depends on the cross-link, of the shape memory polymers.

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In the present paper, fiber optic sensors were employed for measurement of cure index of GFRP laminates. The refractive-index sensors were embedded in laminates during hot press molding. At first, the sensors were embedded along 0 and 90 directions of unidirectional laminates and uniform temperature was applied to materials. From the results, it was found that cure index curves of all sensors were very similar to each other. Therefore, it can be said that reinforcements did not affect cure index measurement of laminates. Secondary, three sensors were embedded in thick GFRP laminates and thickness-wise temperature distribution was generated in the laminates by applying different temperature on each upper and lower side. From the experimental results, we could successfully calculate cure index curves of the laminates at the embedding points. The cure index curves showed that the thickness-wise distribution of cure index generated during cure process. From the results, it was found that the embedded refractive-index sensors are very powerful for investigating cure index distribution of thick FRP laminates.

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In recent years, injury of personnel by bomb called IED (Improvised Explosive Device) is increasing in conflict areas. Therefore, MRAP (Mine Resistant Ambush Protected) and BMS (Blast Mitigation Seats) are being developed in some countries. In this paper, we describe the shape of the seat to reduce the effect of the stress-wave from the explosion-shock for BMS, and the effect was confirmed by experiment.

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The axial crushing behavior of metal honeycombs was studied primarily by the experiments with laying emphasis on the effects of strain rate on those characteristics as energy absorbers. To evaluate the strain rate dependence of materials, A3003 aluminum alloy, SUS430 stainless steel and C1100 tough-pitch copper were used to fabricate honeycomb structures in laboratory. Then, the axial crushing tests under low-speed and free-fall impacting conditions were carried out. SUS430 and C1100 show certain strain rate dependence so that fabricated honeycomb structures also show strain rate sensitivity to some extent. However, the deformation of axial crushing honeycomb is not uniform but is localized at each stage of the progressive plastic buckling. The results show the effect of strain rate on an indicator of energy absorption ability such as mean buckling stress is less than that on the flow stress of foil material itself. The numerical simulations, which took the influences of the plastic deformation of adhesive layer and the fracture of adhesively-bonded joint into consideration, were also conducted by the FEM code LS-DYNA to confirm and understand the behavior.

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Recently, theoretical computational studies have proposed several structures of high pressure phase of carbon. Although some of these proposed phases of carbon have been synthesized at high pressure, they have not been observed at normal pressure. In this study, we made mixtures of copper powder with graphite powder to control shock temperature rise and to quench efficiently, and shock compressed it using powder gun. Several new peaks were observed in XRD patterns of the carbon component after shock compression, which suggest existence of S-, R-, W-carbon phase.

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In the present study, the effect of strain rate on compressive properties of the foamed PE film was experimentally investigated. The dynamic test was carried out at the strain rate of 10^1s^<-1> using a drop-weight testing machine with opposed load cell, which can evaluate the dynamic stress equilibrium during the deformation. Quasi-static test was carried out at strain rates of 10^<-4> to 10^<-1>s^<-1>. Within the set of experiments, the compressive stress was increased and the densification strain was decreased with increasing the strain rate. The plateau deformation was observed immediately after the compressive testing started, with no linear-elastic response phase. It was clarified that the change of strain rate sensitivity was appeared at the strain rate of 10^<-2>s^<-1>.

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In order to clarify the effect of strain rate and test temperature on the compressive strength of polyimide foam, a series of compression tests for the polyimide foam with two different densities were carried out. By using three testing devices, i.e. universal testing machine, dropping weight machine and direct impact apparatus, we performed a series of compression tests at various strain rates (10^<-3>〜10^3 s^<-1>) and at several test temperatures in the range of -190 ℃ to 270 ℃. At over 100 s^<-1>, the remarkable increase of flow stress was observed. The negative temperature dependence of strength was also observed.

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In order to study the influence of parameters of sand under high-speed penetration into sand, we performed the impact experiments by using the powder gun within a velocity of 150-510 m/s. Grain size and packing density of sand were varied several kinds. Impact and penetration speed of a projectile were measured by coil method that is contactless. The behavior of projectile changed at transition speed and the acceleration of projectile was expressed two equations depending on the speed region. We also performed the measuring experiments of the elastic wave speed in sand by using Split Hopkinson Pressure Bar (SHPB) method to compare with the transition speed. It was found that the transition speed give a fairly good agreement with the elastic wave speed.

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In order to estimate parameters of the simulation model for iron green bodies of press-ready premix consisting of Distaloy AE, 0.5 % graphite and 0.6 % Kenolube, we carried out diametrical compression tests of the iron green bodies. We prepared the iron body with densities of 6.9 g/cm^3, 7.2 g/cm^3, 7.4 g/cm^3. The parameters of failure envelope in the modified Drucker-Prager Cap model were determined using the results of uniaxial compression tests in our previous study and diametrical compression tests.

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The purpose of this study is to prevent the reduction of frictional coefficient of C/C composites at low temperature to moderate the dependence of the frictional coefficient on the temperature condition. In this study, the char matrix of C/C composites was prepared from phenolic resin. The phenolic resin was modified with micro sized glass fibers referring the results by previous studies, in which friction coefficient had been improved by the addition of short glass fibers into some conventional friction materials. The results of frictional tests under various temperature conditions and observation of the frictional surface after the tests suggested that the reduction of frictional coefficient at low temperature was prevented due to the scratching with SiC particles which was fabricated in the body of C/C composites modified with micro sized glass fibers and the dependence of the frictional coefficient on the temperature condition was moderated.

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In high-precision work, the workpiece was grinded by high-speed-spinning abrasive wheel. The abrasive product was fractured for misoperation or malfunction, and then this fragments fly apart at high speed. Thus, it is important to resolve the impingement problem of the abrasive and the cover materials. However, the shatterproof cover for the fractured abrasive product is designed experientially. In this study, we develop the collision test apparatus for wheel cover safety in order to set the ISO standard.

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Numerical method to evaluate the correction factor for getting the true uniaxial flow stress is verified. The correction factors for ferrous metals and aluminum alloys are obtained. It is clearly shown that the Tanimura-Mimura 2009 (T-M 2009) Model is effective in simulating the dynamic stress-strain curves especially for large deformations reaching fracture.

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Hypervelocity impact experiments were performed on transparent materials, SiO_2 glass and polycarbonate, to investigate the impact-induced damage process. Stress wave propagation and damage evolution associated with hypervelocity impact were visualized using a high-speed video camera. Recorded images clearly showed how stress waves propagate and interact each other, and how damages form and propagate during hypervelocity-impact event. For examples, the interaction of the transversal wave with the longitudinal wave reflected from rear surface initiated the drastic nucleation of damage points in SiO_2 glass. In the case of polycarbonate, delamination was initiated by the interaction of the reflected rarefaction waves from both side surfaces. Such information provides a valuable insight into the fundamental understanding of the hypervelocity-impact damage process on glass, ceramics, and polymer materials.

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