This paper reports the preliminarily experimental results of low velocity soft-body projectile made of gelatin solution impact test on a thin plate at impact speed of about 120 m/s. An experimental investigation of low velocity impact was performed by using a ballistic range at Institute of Fluid Science, Tohoku University. The process of impact and shock wave propagation phenomena was visualized by shadowgraph method and recorded by a high-speed video camera.

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This paper reports a preliminary numerical result of shock wave interaction phenomena with the brain model. Micro-explosive induced shock wave was propagated and interacted with the brain model made of simulated biomedical materials (acrylic and gelatin solution). The process of shock wave interaction with the brain model was simulated by using hydrocode ANSYS AUTODYN. The shock wave was transmitted into the brain model and propagated at the gelatin solution, reflected at the other side of inner acrylic sphere. The numerical results were compered with the experimental results of shock wave propagation shadowgraph images and pressure history in the brain model.

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This paper studies the vibration energy harvest and response characteristics of poled barium titanate (BT) unimorph cantilevers both analytically and experimentally. The unimorph cantilever consists of the BT layer and Cu shim, and the BT layer has sensing, grounding and driving electrodes. The output voltage of the cantilever excited by bending vibration was predicted by three dimensional finite element analysis (FEA). The output voltage was also measured, and a comparison was made between prediction and experiment. The effects of sensing electrode geometry and load resistance on the dynamic electromechanical fields and output power were then discussed in detail.

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To ensure safety against the explosion of compressor shell induced by detonation of flammable gass has been required in air-conditioning machine and the safe design technique is expected. In this study, the explosive strength property and deformation behavior of low carbon steel pipe used for compressor with high strain rate were examined as a preliminary study. The influence of the pressure buildup rate exerted on fracture mode was found.

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In this study, collision and braking behavior and braking distance of the enforcement device were investigated for characteristic evaluation. The basic theory for the braking distance was derived using the impulse momentum equation and the law of the conservation of energy. By this basic theory, effective arm angle range of enforcement device was clarified. And also, the collision test was carried out by simple model of the enforcement device and the vehicle. The behavior of the enforcement device was examined by the simple model with 3 kinds of different arm angles. The braking distance by the experiment was well agreement with theoretical result. It is possible to optimize and improve the enforcement device by these evaluations of collision behavior.

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In terms of reducing CO2 emission, car structures should be lightened using newer materials such as aluminum alloy, fiber reinforced plastics, etc. The most critical issue for the structures is joining methods because conventional methods such as welding are not suitable for the purpose. Adhesive joining can be applied to the materials, even if different ones of them have to be joined. The presentation treats recent progress of adhesion technology for car structures, especially carbon composite or multi material bodies.

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In order to establish simulation techniques for electromagnetic forming, we have carried out a simulation of the electromagnetic flux compression method using a three dimensional finite element method code with capability of the thermal-structural-electromagnetic coupling feature. It is found that the ultra-high magnetic field less than 100 T as a function of the diameter of the coil can be predicted. A discussion is presented to obtain more precise result over 100 T.

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In the present study, the behaviour of the entrapped fluid in the foamed structure associated with the impact compressive deformation was experimentally investigated. The impact test was carried out at the strain rate of 10^3s^<-1> using a Split Hopkinson pressure bar method. The observation of the entrapped fluid in the foamed structure was utilized the schlieren method. Schlieren method is required the density difference in the visualization of entrapped fluid. Therefore, the entrapped fluid in the cell displace with the carbon dioxide gas. In the foamed film with open cell, the outflow of the entrapped fluid was observed after the impact compressive test. On the other hands, it was clarified that the outflow of the entrapped fluid was not observed in the foamed PE film with closed cell, which indicated that the closed cell was not fractured at the impact test.

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Polypropylene (PP)/glass fiber (GF) and PP/GF/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 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/GF composite. Results show that tensile strength of PP/GF was improved by CaCO_3 compounding. The improvement effect was depended on the diameter of CaCO_3 particles and wettability between GF and PP.

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The purpose of this study is to propose a technique to reduce the torque applied onto driven shafts of monorail for forest industry. To reduce the maximum torque, the modified power train are proposed. The variations of torques of driven shafts were measured with respect to the rotational angle of shaft when the driven pinion gears were engaged experimentally with original and worn rack rail in which the wear depth of tooth was w=3mm, respectively. When the modified power train concurrently driven by v-belt was applied, the maximum torque of rear driven shaft was decreased remarkably. The torque contribution ratio of rear driven shaft was reduced down to about 63% by applying modified power train, while that was 89% through the conventional power train, even when the test systems were driven on worn rack rail. The slip ratio between v-belt and rear driven pulley was increased and the peak torque of rear shaft was reduced due to application the modified power train concurrently driven by v-belt.

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In this paper, a novel experimental method was proposed for evaluating the energy absorption capability of composite materials under impact loading. Split Hopkinson pressure bars system was employed to perform the crushing tests at high strain rate. Progressive crushing behavior was successfully achieved by using a coupon specimen and anti-buckling fixtures. Consequently, the energy absorption per unit volume decreased with increasing strain rate. Microscopic observation of damaged region suggested that the increase in delamination area led to the reduction of energy absorption capability at high strain rate.

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Laminated textile FRP has geometric variability such as scattered volume fraction and lamination misalignment due to molding process. In this study, by modeling the fractured microstructural geometry, focusing on the distributed volume fraction, misalignment, Monte Carlo FEM simulation has been carried out to predict the knee point stress.

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Fluid-structure interaction is one of the most important phenomena to be clarified and controlled in many industrial fields. In some problems, interaction mechanism strongly depends on wave propagation across the interface of solid and fluid. Although many studies have been conducted about fluid-structure interaction, the mechanism of wave propagation across to the solid-fluid interface remains unclear. In this study, we investigated the effect of surface conditions such as surface roughness and wettability of solid materials to wave propagation across the interface. The results of the experiments indicated that due to the wettability of the solid surface, the intensity of the cavitation which appeared near the interface was changed and theoretical assumption of the interface continuity may not be valid under some conditions.

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For the collision safety improvement of the automobile, it is necessary to examine not only the mutual accident of the automobile but also the collision damage by the motion after the accident. However, the verification by the collision test is not reported on the automobile motion after the accident, though the theoretical analysis has been attempted. In this study, in order to clarify the automobile motion after the collision, as the first step, the motion after side collision was investigated by carrying out the model collision test and theoretical analysis. Change in center of gravity position by the automobile motion after the model collision test showed good agreement with the theoretical analysis result. It is possible to estimate the motion of the automobile after side collision from the initial condition before the collision accident.

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Indentation is commonly used to investigate the elastic and plastic properties of materials, which include strain rate dependence. In this study, in order to propose a new indentation concept, which involves the representative strain rate, a finite element method analysis based on the strain rate dependence of materials was used. In order to generate an index of strain rate within the indentation, a strain rate distribution averaging was performed. The strain rate distribution was averaged using the critical and representative strain boundary values of the indentation. It was determined that the relationship between the average strain rate and the loading curvature could be expressed using the dynamic constants of the Cowper-Symonds equation. This allowed for the development of a modified Kick's law that included the effect of strain rate in the indentation analysis. Furthermore, the average strain rate calculated using the representative strain could be defined as the representative strain rate for the indentation from the results of a parametric analysis. These results depended on the work-hardening coefficient and the indenter angle. Therefore, the representative strain rate, which revealed a new indentation parameter, was proposed

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We examined ejecta size distribution when aluminum alloy 2017-T4 spheres with a diameter of 1.6, 3.2 and 7.0 mm impacted aluminum alloy 6061-T6 targets with a plane surface at several impact velocities. We used a two-stage light-gas gun at the Institute of Space and Astronautical Science (ISAS)/Japan Aerospace Exploration Agency (JAXA) and Nagoya Institute of Technology. The size distributions of the ejecta were examined in detail and we compared the size distribution of the ejecta when impacting on the plane surface target at several impact velocities. The scaling law of ejecta size was discussed.

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Unidirectional carbon/epoxy (T700SC/2592) adhesively-bonded by EP008 specimens were evaluated under decreasing energy release rate (G_<max>) conditions. Mixed mode fatigue crack growth behaviour of CFRP adhesive joint were investigated by mixed mode flexure (MMF) test at several loading rate of 0.1Hz, 1.0Hz and 10Hz. Experiments were conducted under linear fracture region. Thus by using compliance method, fatigue crack growth behavior of CFRP adhesive joint can be evaluated from energy release rate (G_<max>) condition for each specimen. Experiment results showed that threshold values did not dependent on loading rate but in higher energy release rate (G_<max>) region, dependency on loading rate has been confirmed. In addition, brittle fracture surfaces were identified when observed by scanning electron microscope (SEM).

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Hypervelocity impact experiments were performed on polycarbonate plates to investigate the penetrating dynamics of hypervelocity objects. The penetration behavior was observed using an ultra-high-speed video camera. The penetrating motion of projectile is analyzed by various penetration models. The penetration behavior of an intact sphere projectile is well described by the penetration model based on the spherical cavity expansion theory.

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The ultrasonic wave transmission behavior through a unidirectional CFRP laminate with spring-type interlayer interfaces immersed in water is investigated using the stiffness-matrix approach. The amplitude transmission coefficient is shown to be influenced by the frequency, angle of incidence, and interlayer interfacial stiffnesses. Using Floquet's theorem, the band structure of Floquet wave propagating in the infinitely laminated structure is computed and compared to the transmission coefficient of the immersed laminate with finite number of plies. This reveals that the band-gaps of Floquet waves are in good agreement with the region where the transmission coefficient falls to a low level, indicating that the band-gaps do appear even in the laminate of finite thickness.

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An impact deformation behavior around the interface between materials having different elastic wave velocities is observed using mesh based digital image correlation method. A bi-material which is made of PMMA resin and polyurethane resin is used for the specimen. A random pattern is painted on the observation surface of the specimen for tracking the surface displacements. The impact load is applied to the specimen using a split Hopkinson pressure bar method. Images of the stress wave propagation parallel to the interface are recorded by the high-speed camera having the frame rate of 1 million frames/s. Displacement and strain distributions are obtained by mesh based digital image correlation using the finite element mesh that boundaries of the elements are set along the interface of the bi-material. As a result, strain components of the deformation field around the interface are obtained.

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In recent years, injury of personnel by bomb called IED (Improvised Explosive Device) is increasing in conflict areas. Jr is difficult to find IED, because there are many different type of IED and the explosion power is not constant. Therefore, MRAP (Mine Resistant Ambush Protected) Vehicle and BMS (Blast Mitigation Seats) are being developed in some countries. In this paper, we develop the system of the seat to reduce the acceleration from the explosion-shock for BMS. We developed new electromagnetic support system. The response of new system is more quick than the conventional mechanism and the response threshold is adjustable. The effect of the electromagnetic support system was confirmed by experiment.

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In order to improve the tensile properties, crosslinking agent was added to PLA/PBAT polymer alloy. We compared the effect of the powder type and liquid type crosslinking agent. Also the tensile properties of PLA/PBAT specimens were measured using split Hopkinson pressure bar method at high strain rates.

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In order to clarify the location of projectile after penetrating into sand, an originally developed "Magnet-Coil" method using electromagnetic induction was applied. It allows us the multi-point measurement of the location of a moving magnet in opaque media like sands. We have already confirmed that it has sufficient measurement accuracy in the case of straight penetration. However, in our previous experiments, it was found that the penetrating projectile meandered. Therefore, in this study, we conducted free fall experiments in consideration of eccentricity and gradient of falling object and tried to formulation of output signal of coil. As a result, theoretical equations were formulated for the output voltage induced by attitude and trajectory of the magnet.

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The second harmonic generation behavior in Rayleigh wave propagation is studied experimentally using a laser Doppler vibrometer. From the measured wave field, the fundamental as well as the second harmonic components in the Rayleigh wave are obtained by the spectral analysis, and their in-plane distributions on the material surface are examined. The experiments are carried out using transmitting transducers with piezoelectric elements of different dimensions. The results indicate that the diffraction effect of the Rayleigh wave beam due to the finite size of the piezoelectric transducer should be taken into account when evaluating the material nonlinearity in a quantitative manner.

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When a high speed projectile collides with aluminum foam, it has been reported that unique crater which has narrow entrance and large cavity like a turnip is formed. In case of a material with higher porosity, it is considered that debris cloud is produced by the impact, and the crater is created by scattering it into the inside of the material. In addition, melting traces are observed and it is predicted to melt with heat created by the impact. As one of measurement methods of the transient impact temperature, measurement of plasma induced by high speed impact using triple probe method were investigated due to record temperature changes near the impact point, which contribute to elucidate the crater formation mechanism. In order to improve the reliability of plasma measurement, the plasma was observed using high speed camera.

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Type3 Carbon Fiber Reinforced Plastic(CFRP) accumulators widely used at the hydrogen fuelling stations. The safety of the vessels has been mostly examined by the experimental results so far since the FEM modeling of CFRP layers is very difficult task. The difficulties come from the dome region modeling because fiber orientations and the thicknesses of CFRP layers vary locally. In our previous study, we have developed the computer software which can model the accumulators as the complicated layered structures. The stress at the liner dome region is important factor for the safety of the vessel, and it depends on its shape. With the software above mentioned, we can easily change the dome shape of the vessel in the finite element modeling. In this study, optimization of the shape using Downhill Simplex method is carried out to reduce the maximum stress of the liner at dome.

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The hydrogen micro-print technique is one of ways to detect hydrogen which diffuse into several materials. By using this technique, we can indirectly observe a diffusible hydrogen with silver particles which is created from reduction of a silver bromide (AgBr) solution. Although, the repetition reproducibility of this technique have been not reported. In this study, the best procedures to obtain a reproducible analysis results have been investigated. For proofing this procedures, some materials - SUS316L for metallic materials and two types of plastic materials - that were exposed high pressure hydrogen were analyzed with a hydrogen micro-print technique.

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High pressure hydrogen gas is used in the Hydrogen society. In Japan, 100 hydrogen stations are planned to be constructed by the end of 2015. One of the issues of the hydrogen station construction is the high cost. In order to decrease the cost, one of the ways is appropriate use of low-cost materials. For the purpose, various material data under the high pressure hydrogen gas are requested. However, evaluations of material properties under high pressure hydrogen gas are difficult because special equipments are necessary and the costs to install those machines are very high. Therefore, an alternative method for the mechanical property evaluation under high pressure hydrogen gas was investigated in this study. A tempered martensitic JIS SCM435 steel with tensile strength of 1000MPa grade was used. Fatigue property was evaluated with cathodic charging with 0.1M NaOH solution and the current density of 100A/m^2. The evaluation result was compared with the fatigue result under 115MPa hydrogen gas environment. The fatigue evaluation result obtained with the cathodic charging method was almost the same as the result under 115MPa hydrogen gas condition.

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In order to reveal the effects of hydrogen on reversed torsion low cycle fatigue of a carbon steel JIS-545C, strain controlled low cycle fatigue tests were carried out under reversed torsion loading using hydrogen charged and uncharged specimens. The specimens were polished with buff, and then were charged hydrogen by immersing in 20 mass% NH_4SCN solution at 313 K for 48 hours. The failure lives of hydrogen charged specimens are the almost same as those of uncharged at the Mises strain range from 0.5% to 1.2%, however, the failure lives of hydrogen charged specimens are longer than those of uncharged at the Mises strain range of 1.5%. There is a slightly effect of hydrogen charging on stress-strain relation, and the stress range of hydrogen charged specimen becomes smaller than that of uncharged.

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Crack growth characteristics of stress corrosion cracking (SCC) and fatigue crack growth (FCG) were investigated for three types of aluminum alloys expected for hydrogen containers in humid air of RH > 90% and 3.5% NaCl solution. The materials were prepared to have different grainsizes. Based on the results, requirements of material were discussed for hydrogen containers.

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We used a Kriging model for time-domain reflectometry (TDR) measurements where the transmission line was placed as a two-dimensional shape. The damage can be clearly detected on the transmission line through the application of a 2D microstrip line differential circuit for TDR. The reflection voltages between the observed points are interpolated, and the uncertainty is obtained by Kriging. We integrated the estimation and uncertainty contour maps into a single figure for easier understanding and statistical quantification. We used the measured TDR data to investigate three types of visualization models for damage inspection: hue-saturation-intensity color, crack existence probability, and expected improvement. All three methods quantitatively visualize the estimated crack configuration with uncertainty in a single figure. By operating these visualization models depending on the inspector's preferences, more appropriate crack estimation can be performed for wide-area fast scan-type inspections such as TDR. In particular, the latter two models can be directly used as an evaluation index for secondary inspection.

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Graphene and carbon nanotube (CNT) exhibit excellent mechanical, electrical, and thermal properties. In a previous study, these materials were derived from sp2 bonded carbon atoms closely packed in a honeycomb crystal lattice. However, there were several problems with the derived materials including suboptimal mechanical properties, slippage within the graphene surface, leakage CNT from the resin, and lack of bonding between nanomaterials. To address the aforementioned deficiencies, we proposed the fabrication of a graphene CNT hybrid material (G-CNT) consisting of an extensive network of chemically bonded layers. Chemically bonding was performed via dehydration synthesis of amino and carboxyl groups. To analyze the produced material, we employed Fourier transform infrared spectroscopy (FT-IR) and tensile tests. The FT-IR spectra confirmed, amino modification of graphene, oxidation of carboxyl modified CNT, and oxidation of the amide group of G-CNT. The tensile tests, demonstrated that PVA films containing G-CNT have high ductility in comparison to both pure PVA and PVA lacking chemically bonded CNT and graphene.

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Wood is a complex material which has late part on a hard layer and early part on a soft layer. In order to expand an application of wood, the mechanical properties of wood should be investigated. In this study, the indentation test to the micro region of wood is carried out. The mechanical properties of wood can be given by comparing the experience data and FEM analysis data. In FEM calculations, the mechanical behavior of the wood is described on a viscoelastic material by using Prony series.

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Dry textiles are usually incorporated into the RTM method as a fibrous reinforcing material. The architecture of the textile material affects both the permeability and material properties of the final product. We optimized the textile architecture to improve manufacturing efficiency and product quality. In this optimization, in-plane stiffness, in-plane permeability, out-of-plane stiffness, and out-of-plane permeability were calculated via the homogenization method in the liquid and solid phases as objective functions. We use a multi-objective genetic algorithm as an optimization technique. A self-organizing map was used as a visualization tool. As a result, we obtained a Pareto solutions group, which is significant in designing the architecture of the textile. We demonstrated the design rules and knowledge of fabric structure by analyzing the Pareto solutions.

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Soldering is essential technique for assembly of parts of cars, devices, IC's, and so on. The main component of solder is tin. We electrochemically analyzed the oxidation rate of tin because that the oxide thickness affects the strength of oxide film on tin surface. The methods we used are measuring polarization curve and exposed test in several pH solutions. The polarization results show that the oxidation rate in acidic or alkali solution is 10 times higher than in neutral solution. The oxidation mechanisms of tin are also different. The oxidation rate is controlled by oxide supply in acidic solution. The rate is controlled by metal dissolve reaction in neutral solution.

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Carbon fiber reinforced plastics (CFRP) have microscopic inhomogeneity. It is necessary to consider the effect of inhomogeneity in order to improve accuracy for analysis of CFRP structures. In this study, we constructed multiscale simulation method for CFRP plate structure using commercial FEM code, Abaqus. Multiscale simulation consists of microscopic, mesoscopic, and macroscopic scales. In microscopic scale, we obtained material properties of unidirectional fiber tows from material properties of fiber and resin. In mesoscopic scale, CFRP plate stiffness including out-of-plane shear stiffness was calculated for analysis with shell element. Macroscopic analysis was conducted by using plate stiffness and shell elements. Finally we compared results of three-point bending tests including short beam tests with shell element analysis. In three-point bending tests and analysis, we changed aspect ratio by changing jig span. In both of them, when aspect ratio decreases, apparent bending modulus decreases. Analysis showed good agreement with experiments.

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In vacuum assisted resin transfer molding (VaRTM), flow monitoring was extensively investigated to suppress molding defects. However, flow monitoring technics in which a sensor is not buried inside the molded article cannot provide sufficient data for three-dimensional monitoring. In this study, we proposed a three-dimensional flow monitoring technique that does not involve burying a sensor inside the molded article. We acquired the three-dimensional data by a data assimilation method integrating stochastic simulation of resin flow during a VaRTM process with the observation of flow front location and reconstructed a three-dimensional resin flow. The proposed technique was validated through a numerical experiment. The result confirmed that our technique could estimate the three-dimensional resin flow. In addition, we confirmed that the permeability could be estimated.

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La_<0.6>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. The purpose of this study attempts to clarify a variation of oxygen non-stoichiometry in LSCF under axial compression. An electrochemical cell consisting of YSZ (yttria stabilized zirconia)/LSCF/YSZ with glass sealing is prepared, which is examined using oxygen coulometric titration. The change in oxygen nonstdichiomery obtained in this experiment wa by two order smaller than the literature value. Theoxygen nonstoichiometry increases with the applied stress, wich could be due to an enlargement of effective contact area between YSZ/LSCF.

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A piezoelectric element generate voltage by piezoelectrical effect The piezoelectrical effect converts load into an electric charge. In this study, we invent power generator using the piezoelectric element (PZT). PZT is attached to the round fan. When the handle of the round fan is swung, the equipment with PZT is subjected to the repeating load Thus, the round fan is considered as a power genaator. We made the experimental device which modeled the handle of the round fan. We measure the output voltage and the electric power with various values of electrical resistance. The relationships between the output voltage, the electric power and the load resistance can be given.

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Very high cycle fatigue properties of β-titanium alloy were evaluated by using an ultrasonic fatigue testing machine. A S-N diagram and fracture morphology of β-titanium alloy Ti-22V-4Al in very high cycle region were investigated. Fatigue failure in very high cycle region was observed. The influence of cyclic frequency was confirmed in comparison with experimental results at standard cyclic frequencies.

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During resin impregnation into fiber bundles in vacuum-assisted resin transfer molding (VaRTM), entrapped air in resin may remain as voids in the products. Since the presence of the voids deteriorates the composites mechanical properties, prediction of the void generation is required. The purpose of this study was to evaluate the effect of the resin impregnation angle in an anisotropic fabric on the relationship between the amount of voids formed and the resin velocity. We performed experiments on 2D radial-injection VaRTM using laminated anisotropic plain-woven fabrics, and determined the void distribution and the formation of the void. Based on the experimental results, we developed a mathematical model for predicting the void formation for an arbitrary impregnation angle and velocity. Comparison of the model predictions with experimental results revealed good agreement.

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Dislocation emission phenomena from Al metastable grain boundaries with <110> or <112> tilt axis are researched by molecular dynamics simulations used an EAM potential. Metastable grain boundaries are obtained by controlling the atomistic relative displacement of neighboring grains with a fixed misorientation angle. Analysis models containing metastable grain boundaries are deformed in tension at the strain rate of 1×10^9 1/s at 10 K. As results, the relationship between the geometrical information of grain surface steps and the Burgers vector of emitting dislocations is a key factor to the ability of dislocation source of grain boundaries and furthermore the relative displacement of surface steps of each grain also strongly influences the dislocation emission phenomena from metastable grain boundaries.

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La_<0.6>Sr_<0.4>Co_<0.8>Fe_<0.2>O_<3-δ>(LSCF) is expected to be applied as an oxygen separation membrane and cathode for solid oxide fuel cell (SOFCs) because of its oxygen ion conductivity. In particular, the oxygen ion conductivity of LSCF is an important characteristic that determines the performance of the device. Meanwhile, LSCF in practical use involves a thermal and chemical strain-stress due to temperature and oxygen partial pressure changes; therefore, it is concerned influence of the ionic conductivity. In the present work, polarization-depolarization tests of 8YSZ/LSCF/8YSZ cell under uniaxial compression loading were conducted and effects of stress on the ion-conducting were investigated. Although a clear correlation was not obtained for load stress dependency of the depolarization curve and chemical diffusion coefficient, the oxygen-ion conductivity/electronic transport number was found to increase as the applied stress increases.

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For the structural integrity assessment of the sandwich structural leaf spring installed on the rolling stock bogie "efWING", Electrical Resistance Change Method using the electrical conductivity of carbon fiber has been studied. In the present study, electrical resistance change of fatigue-loaded test coupons is experimentally measured and an inner damage is captured by ultrasonic testing. The relationship between electrical resistance and an inner damage is analytically investigated using FE analysis. As a result, the study shows the electrode producing a high current density in through-thickness direction is effective to detect an inner damage.

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To investigate the development of non-uniform deformation behavior of material, uniaxial tensile test of polycrystalline pure copper specimen was carried out. The specimen with different grain sizes were prepared by controlling annealing condition. To cause the non-uniform deformation to the specimen curved gage section was given. Strain field was evaluated by digital image correlation method. Grain size influenced the development of non-uniform deformation.

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This paper deals with the influence of loading condition on crack growth rate by stress corrosion cracking (SCC) in an austenitic stainless steel. Three types of SCC tests, in which the stress intensity factor K was increasing, constant and decreasing, were conducted under large-scale yielding condition (LSY). The crack growth rate under LSY was characterized by the equivalent stress intensity factor K_J obtained by J integral. The crack growth by K-increasing test was faster than that by K-constant or decreasing tests at the same K_J level, and this result shows that the crack growth rate increased with increasing dK_J/da even if under the same K_J level. It is concluded that the crack growth rate by SCC could be characterized by K_J and dK_J/da.

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As a result of high temperature rotary bending test of modified 9Cr-1Mo steel, the reduction of the misorientation and change in the martensitic structure were observed at the surface of damaged specimens. In addition, nano-indentation test was performed on the surface of the fractured specimens to evaluate the decrease of the strength of this alloy due to the change of the micro texture. Based on the results of the hardness test, modified normalized S-N curves was proposed by considering the change of the 0.2% proof strength of the material.

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In order to enable the precise position control of machines and prevent various machinery failures in advance, it is necessary to monitor the stress and strain fields in the working parts with high sensitivity. Therefore, the authors have developed a strain sensor on a flexible substrate using graphene as a material for highly sensitive and micro-sized strain sensor. In this study, chemical vapor deposition (CVD) method was used for the synthesis of graphene on the Cu foil. After the synthesis, the graphene sheet was transferred on a Si/SiO_2 substrate and a graphene-based strain sensor was fabricated by applying MEMS technique. The strain dependence of the electrical conductivity of the sensor was evaluated.

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In this study, the dominant diffusion path in the electroplated copper interconnections used for TSV (through silicon vais) was investigated in detail under the EM (Electromigration) load. The micro texture of the interconnection was analyzed by using an EBSD (Electron Back-scattered Diffraction) method. There were two dominant diffusion paths: the interfaces and random grain boundaries formed at the center of the interconnection. Both paths consisted of porous random grain boundaries with low crystallinity. The random grain boundaries at the center of the interconnection remained even after the annealing at 400℃. Therefore, it is necessary to improve the crystallinity of the as-electroplated film to improve the EM resistance of the electroplated interconnections.

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A tensile test method that can measure the strength of a grain boundary has been developed by applying a focused ion beam system. In order to investigate the effect of crystallinity of grain boundaries on their strength, an electron back-scatter diffraction method (EBSD) was employed for the quantitative characterization of grain boundaries. It was confirmed that the strength of grain boundaries with low crystallinity was much lower than that with high crystallinity.

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