The parent phases of many shape memory alloys (SMAs) are B2 or dis-ordered BCC crystal structures and the order of symmetry of martensite of the SMAs possesses lower symmetry than those of parent. Assumed that a polarity exists in the atomic binds at parent crystals, its motif lets the order to be lower than parent's symmetry. This potential symmetry in each parent crystal will be determined using by the point group theory so that there are 12 unique polarity arrangements. Furthermore, the four neighbor atomic relations are found according to consider polarities with the unique arrangements. This classification applies to the crystal symmetry in martensite of the SMAs.

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Biocompatible piezoelectric materials are becoming increasingly important for actuators and sensors in medical devices. In this study, we examined the possibility of five perovskite-type silicon oxides MgSiO_3, MnSiO_3, FeSiO_3, ZnSiO_3 and CaSiO_3, which have been found from the stable combinations of biocompatible elements in our previous studies, by employing first-principles calculation. At first, the stable cubic structure and the phonon properties were analyzed for the paraelectric nonpolar phase. After the promising silicon oxides were distinguished with the phonon eigenfrequency and eigenvector in consideration of the structural phase transition, their characteristics of stable tetragonal structure were then analyzed for the ferroelectric phase. Computations indicated that MgSiO_3 has superiority on the phase transition from cubic structure to tetragonal one. Additionally, tetragonal MgSiO_3 has a large spontaneous polarization and it can exhibit the largest piezoelectric response.

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In this paper, the elastoplastic collapse of square tubes subjected to the statically pure bending is studied by using the finite element method (FEM). It is found that there are three types of collapse modes. The first type is a collapse mode due to buckling at the compression side. The second type is a collapse mode due to flattening of the cross section. The third type is a collapse mode by mixing the first type and the second one. Based on these facts, approximate numerical methods to estimate the maximum moment of these collapse modes are proposed, and their validity are verified by comparing with numerical results of FEM.

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Recent advancement in ability of a computing machine has developed an active trend for replacing an experiment with a simulation. In order to perform the analysis of a real structure pertained with extremely large fluctuations, both geometrically and materially, a large number of elements are required, and efficient analysis is indispensable. In contrast, it is often the case that an actual structure has a symmetrical shape in whole or in part, and its boundary value also have a symmetrical distribution. Therefore, there have been proposed a number of analytic techniques that take advantage of a symmetry of a structure. However, symmetry includes wide variations, such as plane symmetry, inverse symmetry, axial symmetry, helical symmetry, and short cake symmetry. Further, the generation method of a mirror image, the number of mirror images to be generated, and so on are different in each case. Therefore, a program corresponding to each case must be configured. Further, the presence of a problem of a mixture of different types of symmetry such as mixture of plane symmetry and axial symmetry increases the number of cases to be coped with, which causes serious problems in maintenance and expandability of a program. This paper has proposed a boundary element method processing boundary condition information and geometrical information individually as a method of efficiently analyzing structures that are symmetrical in geometry and boundary conditions, and has confirmed its validity through analyses of electrochemistry. Further, the proposed technique makes it possible to reduce analysis time significantly.

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In this paper, vapor-grown carbon fiver (VGCF), which is a kind of carbon nanotubes (CNT), is used for the composite materials with aluminum matrix. It is found out that the thermal conductivity of the composites is about 2.5 times higher than that of the pure aluminum of the matrix if the direction of VGCF is aligned. To improve the thermal conductivity of the composites, small amount of CNT were added to the VGCF filler. The effect of the addition of CNT on the thermal conductivity was examined by both the finite element analysis (FEM) and the measurements of the thermal conductivity. Simulations of finite element analysis (FEM) shows that the possibility to improve the thermal conductivity with small amount addition of CNT because of the cross-link (VGCF-CNT-VGCF). Therefore, small amount of CNT are added to the VGCF/aluminum composites. The thermal conductivity of the composites added CNT have about 20% higher thermal conductivity than that of the composites without CNT. The cross-links of VGCF due to the CNT addition is also confirmed by FE-SEM observation.

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Metal injection molding (MIM) is a suitable production technique for the mass production of the products of the complicated shape. However, the studies on the dynamic properties such as the fatigue strength of the materials produced by the technique are not enough. Our aim is to evaluate the fatigue damage of the materials with AE method. In the previous study, the detected AE signals during the fatigue testing of the material were analyzed, and the possibility of the damage evaluation by the analysis method that was proposed was shown. In this study, it was examined to evaluate the damage by the moving average of the largest lyapunov exponents of the signals. As the result, it became clear that the damage is quantitatively evaluated by observing the difference in the average of the exponents of the high and low frequency components of the detected signals, and the damage is evaluated in the real-time.

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A simple yet accurate constitutive model for piezoelectric materials is proposed. The model is derived under the following two assumptions. (i) Infinitesimal crystals in a piezoelectric material are considered, and the order of the energy required for the switching in a crystal is unchanged independently of the switching directions. (ii) The required switching energy is given in the form of a sum of two exponential functions of phase volume fraction. Comparison of electro-mechanical deformation behaviors between the calculation and the existing PLZT data verifies that this model can duplicate the hysteresis loops of the deformation behaviors among the stress, strain, electric field, and electric displacement. This indicates that the present model can provide a good tool to understand the mechanism of the deformation behavior of the piezoelectric materials and to design smart structures containing the piezoelectric elements.

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Glass/epoxy interfacial tensile strength is investigated by the cruciform specimen method. The conventional transverse tensile test for single fiber composite is one of methods for evaluating the interfacial tensile strength, but stress singularity at the specimen edge is a very complicated problem to be solved. A cruciform specimen which has large width only around fiber embedded in transverse direction can potentially prevent the stress singularity problem. The cruciform specimen geometry is first discussed by means of finite element analysis considering experimental conditions. Transverse tensile test is conducted and interfacial debonding which initiates at the middle of specimen not at edge is observed using the cruciform specimens. The interfacial tensile strength can be obtained by the value of stress concentration factor at interface times specimen stress. The location at which the debonding initiates is discussed and the validity of the evaluation method in this study is verified on an assumption that interfacial tensile strength is as high as or lower than interfacial shear strength.

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When a flaw is detected in a stainless steel pipe during in-service inspection, the limit load criterion given in the standards such as JSME Rules on Fitness-for-Service for Nuclear Power Plants or ASME Boiler and Pressure Vessel Code Section XI can be applied to evaluate the integrity of the pipe. However, in the present standards, the limit load criterion is only provided for the case of single flaw, although multiple flaws such as stress corrosion cracking have been detected in the same circumferential cross section in a pipe. In this paper, a fracture estimation method is proposed based on the limit load criterion for multiple independent circumferential surface flaws with arbitrary number and distribution, to evaluate the integrity of the pipe in a rational way. Several numerical examples are given to show the validity of this method.

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Transient response of an annular crack in a plate of a functionally graded piezoelectric material (FGPM) is studied under thermal shock loading conditions. It is assumed that the thermoelectroelastic properties of the strip vary continuously along the thickness of the strip, and that the crack faces are completely insulated. Some material properties are assumed to be exponentially dependent on the distance from the crack line paralel to the boundaries of the plate. By using both the Laplace and Hankel transforms, the thermal and electromechanical problems are reduced to a singular integral equation and a system of singular integral equations. The singular integral equations are solved numerically, and a numerical method is then employed to obtain the time dependent solutions by way of a Laplace inversion technique. The intensity factors versus time are presented for various values of dimensionless parameters representing the material nonhomogeneity and the crack position.

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This paper studies the elastic constant and microstructure of amorphous SiO_2 (a-SiO_2) thin films deposited on Si substrates. a-SiO_2 thin films were prepared by the reactive sputtering with a Si target in the argon/oxygen mixture gas. We measured the Brillouin-oscillation frequency using a femtosecond pump-probe method. We determined the longitudinal-wave elastic constant from the measured frequency and the refractive index measured by the thin-film ellipsometry. The results show that the elastic constant of the a-SiO_2 thin film highly depend on the microstructure and microcracks. The micromechanics model was developed to explain the decrease of the stiffness with thin pancake-shaped microcracks, which were randomly distributed in the a-SiO_2 matrix. This study demonstrates that the Brillouin oscillation technique is an effective tool for evaluation of not only acoustic properties but also reliability of transparent materials.

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Tensile deformation properties and pulsating-plane bending, alternating-plane bending and rotating-bending fatigue properties of a superelastic thin tube (SE-tube) and a highelastic thin wire (HE-wire) of TiNi alloy were investigated experimentally. The main results obtained are summarized as follows. (1) The stress-strain curve of the SE-tube in tension draws a superelastic hysteresis loop and elastic modulus is 35GPa. Therefore, the SE-tube is superior as a medical catheter tube with flexibility and shape recovery. The stress-strain curve of the HE-wire is close to a straight line up to strain of 4% and stress of 1500MPa and elastic modulus is 50GPa. Therefore, the HE-wire is superior as a medical guide wire with flexibility, high pushability and torque transmission performance. (2) With respect to fatigue properties of the SE-tube and the HE-wire in air, the fatigue life in pulsating-plane bending is longer than that in alternating-plane bending and rotating bending. The difference in the fatigue life between alternating-plane bending and rotating bending is small. The relationship between maximum bending strain and the number of cycles to failure in the region of low-cycle fatigue can be expressed by a power function in every bending fatigue. The fatigue life in the body is longer than that in air. (3) The maximum bending strain at the fatigue limit of the SE-tube is 0.8%-1.0% which is close to a starting strain of the stress-induced martensitic transformation. The maximum bending strain at the fatigue limit of the HE-wire is 0.7%-0.8%.

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Rotating bending fatigue tests have been conducted in laboratory air using type 403 stainless steel with Al_2O_3 coating thermally sprayed by high velocity oxygen fuel (HVOF) process. Two different coating thicknesses of 150μm and 300μm were evaluated. The test results were compared with those of specimens with atmospheric plasma sprayed (APS) ceramics coating, and the effects of coating thickness and spraying process on fatigue behaviour were investigated. The fatigue strengths of the coated specimens were lower than those of the substrate, and decreased with increasing coating thickness when the stress was calculated including the coating thickness in the specimen diameter. On the other hand, the fatigue strengths of the coated specimens were improved compared with the substrate, when the stress was calculated from the nominal diameter of the uncoated specimen. Exceptionally, the HVOF sprayed specimens whose coating thickness was 300μm exhibited significantly lower fatigue strengths than the substrate. The dependence of fatigue strength on coating thickness and spraying process was discussed based on the observation of crack initiation in the substrate and cracking in the coatings.

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The fatigue failure analysis of SUS316L flexible hose of the hydrogen station which was demonstrated during EXPO 2005 in Nagoya was carried out. The fatigue fracture surface where hydrogen leakage was detected showed clear striations which revealed a unique evidence of hydrogen effect on the ratio of striation height and spacing. The number of striations observed on the leakage fracture surface was 270. Considering that the number of hydrogen supply to the fuel cell buses was 280, it can be concluded that the fatigue fracture process during the demonstration is completely controlled by microplasticity resulting ductile fracture contrary to the conventional concept expressed with a term of decohesion or hydrogen embrittlement. The striation data were used to make the fatigue crack growth rate equation which was applied to the life prediction and structural integrity assessment for a new hydrogen station. The fatigue crack growth data showed the evidence of a strong frequency effect of fatigue crack growth rate of SUS316L used in the hydrogen environment with 8 minutes hydrogen supply time at the hydrogen station.

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Copper thin films were fabricated by RF-magnetron sputtering under target power densities of 0.5 and 5W/cm^2. The polyimide film was used as a substrate to apply a plastic deformation to the copper thin film. Average grain sizes of the copper films obtained at 5W/cm^2 were 125nm and 230nm. On the other hand, the sizes at 0.5W/cm^2 were about 50nm. Load-controlled and strain controlled cyclic deformation tests were conducted on the polyimide films where the copper films deposited. Stress, full width at half maximum (FWHM) of diffraction profile, crystallite size, and microstrain of the copper films were measured during the deformation tests using X-ray method. In the load-controlled tests, the crystallite size decreased with applied strain during loading period, although the applied strain hardly affect crystallite size during unloading. On the other hand, the microstrain during unloading period was sensitive to the applied strain: the microstrain increased after initial rapid decrease. In the strain-controlled tests, the X-ray stress averaged over a strain cycle decreased with strain cycles. This is because the copper film was subjected to large plastic deformation which can cause internal compressive stress during unloading. The averaged value of the FWHM decreased also with strain cycles. This decrease in the FWHM was consistent with texture development during cyclic loading. On the other hand, the changes in the crystallite size and the microstrain during cyclic loading were insignificant.

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In a fatigue analysis for Class 1 components in the Rules on Design and Construction for Nuclear Power Plants (The First Part: Light Water Reactor Structural Design Standard) in the JSME Codes for Nuclear Power Generation Facilities, a simplified elastic-plastic analysis is used when the primary plus secondary stress intensity exceeds 3 times the Design Stress Intensity. The simplified elastic-plastic analysis is to multiply elastic-analysis-based stress by a Ke-factor. It is well-known that the Ke-factor of the ASME Boiler and Pressure Vessel Code Section III has a large amount of conservatism. Hence, to develop an appropriate Ke-factor evaluation method, the Ke-factor Advisory Committee was established in June 1999 as a research committee of the Thermal and Nuclear Power Energy Society. Typical basic models were selected from actual structures. Elastic analyses and elastic-perfectly plastic analyses were performed for the basic models and the Ke-factors were calculated. Ke equations were established by bounding the Ke-factors. The new Ke equation was verified by using experimental data of piping. The Ke factors for typical actual nozzles of which Ke-factors were relatively higher were directly analyzed and it was confirmed that the developed Ke evaluation method could be higher than the Ke-factor directly analyzed. Based on those evaluations, the Ke' equation expressed by Primary+Secondary Stress Intensity (S_n) and the Ke" equation expressed by Primary+Secondary+Peak Stress Intensity (S_p) were developed. The Ke' equation has been taken in the JSME Design and Construction Code and the Ke" equation has been taken in the Code Case, "Alternative Structural Evaluation Criteria for Class 1 Vessels based on Elastic-Plastic Finite Element Analysis".

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Strongly motivated by every stakeholder not to repeat Mihama Nuclear Power Station pipe rupture accident in August 2004, JSME Main Committee on Codes & Standards on Power Generation Facilities immediately launched a special task force to develop Rules on Pipe Wall Thinning Management for BWR, PWR and fossil Power Plants respectively. The authors describes the process of the development of Rules for BWR Power Plants from the view point of collections and analysis of fields data of pipe wall thinning. Through its activities, the authors confirmed the existing findings, like the effect of Oxygen injection, turbulance and dependence on coolant temperature, derived from series of laboratory-scaled experiments in FAC and coolant velocities effects in LDI. Further based upon the said proven findings with field data, they explain the adequacy of major concept of the rule such as separate treatment of FAC (Flow Accelerated Corrosion) and LDI (Liquid Droplet Impingement).

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Dependence of notch strength ratio on stress triaxiality and strain hardening exponent was investigated for a variety of structural steels. Both the notched specimens with different notch root radii and the unnotched specimens were employed to obtain a wide range of stress triaxiality. All specimens were loaded up to break under tensile loading at room temperature. Notch strength ratio was defined by a ratio of notch tensile strength to tensile strength of the material. The notch tensile strength required to break the notched specimen depends on the stress-state characterized by stress triaxiality. Notch strength ratio increased with increasing stress triaxiality, which eventually reached the limiting value in the range of high stress triaxiality. The limiting notch strength ratio showed a clear dependence on the strain hardening exponent, and could be used conveniently to estimate the upper limit load to break the mechanical component in failure analysis.

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