Since Ti-Ni based shape memory alloys (SMAs) work well at temperatures less than 373K, SMAs are expect to apply the heat-engine which recovers low-temperature thermal energy. The pulley-type SMA heat-engine, which is one of the SMA heat-engine, is driven by heating of the liner or shape SMA element. However, the pulley-type engine tends to overheat because cooling method is air cooling. Owing to this, generating power decreases with increasing of operating time. We proposed a new cooling mechanism to cool off a pulley by streaming water. In addition, the shape of SMA element is modified into a tape shape from a liner or coil shape for improvement of the output power and fatigue characteristics of the SMA element. This tape shape SMA element is produced by a centrifugal casting method. In this study, the effect of heat-treatment conditions on shape memory characteristics is investigated.

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The purpose of this study is to development weight transfer type heat engine using shape memory alloy. The shape memory springs were made from Ti-50.0 at% Ni wires of 0.8 mm in diameter. The outside diameter of coil is 12 mm and the total coils are 7. The heat treatment conditions are 400 ℃ -1 h and 500 ℃ -1 h. The transformation start temperatures are 39.8℃ at 400 ℃ H.T. and 48.3℃ at 500 ℃ H.T. The 60g weight was used for the heat engine. The results are summarized as follows. (1) The rotation number is 9.1 rpm at 400 ℃ H.T. and 14.9 rpm at 500 ℃ H.T. (2) The output power is 5 mW at 400 ℃ H.T. and 20mW at 500 ℃ H.T.

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The functionally graded shape memory polymer (FGSMP) board laminated by the polyurethane shape memory polymer foam and sheet with different glass transition temperatures was fabricated and the compressive deformation properties of the FGSMP board were investigated. The indentation property of FGSMP board was similar to that of a thumb of a person. The FGSMP board can be applied to the elements coming into contact with the body in the medical actuators.

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In the shape memory alloy (SMA) and shape memory polymer (SMP), not only shape recovery but also large recovery stress, energy storage and energy dissipation can be used. If the shape memory composite (SMC) with SMA and SMP is developed, the new intelligent function of the SMC can be obtained. The SMC belt composed of two kinds of TiNi SMA with different phase transformation temperatures and polyurethane SMP was fabricated. The three-way reciplocating bending movement and recovery force by electric heating were investigated. The multi-functional SMCs with simple structure for intelligent actuators are highly expected.

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Recently, it is attempted to apply Fe-based shape memory alloys to vibration dampers for large-scale structures and pipe joints. Its deformation behavior at higher deformation rate should be investigated because these applications are easily affected by the earthquake. According to the past researches, the positive rate sensitivity can be observed under compressive and bending deformation. It can be considered that its mechanism of rate sensitivity is strongly related to both stress induced martensitic transformation and plastic deformation, however, this idea is not still discussed. In this study, tensile tests of the alloy at wide range of strain rate are conducted. Additionally, temperature rise is captured during the quasi-static deformation. After the quasi-static test, the recovery strain is measured by heating up to A_f temperature. Finally, the rate sensitivity of the alloy is discussed.

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In this study, we have achieved an enhancement in the corrosion fatigue life using the thermal oxidation treatment technique that can generate a passive film on the surface of the TiNi shape memory alloy wire. The procedure for the thermal oxidation treatment is explained as follows. First, the as-received material with oxide film was mechanically polished to remove the film by abrasive paper and a buffing compound. Second, the material was heat treated in the electrical furnace filled with N_2-20 vol% O_2 gas. The heat treatment was carried out for 1 hour at 673 K and subsequently cooled in the furnace. The results obtained can be summarized as follows: (1) The passive film is uniformly generated on the surface of the TiNi shape memory alloy wire by the thermal oxidation treatment on a macroscopic scale and has a noteworthy effect on the improvement of the corrosion resistance characteristics. (2) The corrosion fatigue life of the thermal oxidation treatment is longer than the material that was heat treated in air. We found that the film generated by the thermal oxidation treatment can maintain the adhesion to the base material even when subjected to a bending strain of more than 1%.

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Microchamber devices have been made by using 3d manufacturing technique. Such the chamber is given by pulling silicone rubber from the epoxy mold. In the pulling process, destruction of the epoxy mold is occurred. The pulling mechanism of the silicone is investigated by using the elastic analysis. The silicone rubber is considered as hyper elastic material, such as Neo-Hookean solid. The maximum pulling force can be given as the sum of the thin region. The relationships between the maximum pulling force and the configuration of the mold are given.

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Visco-elastic property of filled rubber is analyzed by large scale numerical simulations. Combining Coarse Grained Molecular Dynamics and large scale Finite Element Method, molecular scale interphase properties and nano-scale filler structure are considered in the analyses. Effect of filler-matrix interaction and filler dispersion are observed in the stress relaxation behavior of filled rubber composite.

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In this study, we investigate the effect of pitch-to-diameter ratio on homogeneous pattern transformation of gel films with a square lattice of holes. Finite element analysis is performed using an inhomogeneous filed theory of polymeric gels in equilibrium. Periodic units consisting of 2x2 unit cells are analyzed with different pitch-to-diameter ratios. Geometrical imperfections are introduced using oriented elliptical holes. It is found that a small imperfection magnitude predicts the transformation into a diamond plate pattern (DPP) regardless of the value of pitch-to-diameter ratio, while a large imperfection magnitude predicts DPP when p/d < 4 but not DPP when p/d> 3. When buckling is dominant, DPPs appear and transformation becomes homogeneous, while, when creasing is dominant, patterns depend on initial imperfections, and transformation becomes inhomogeneous.

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This paper presents stress analysis including geometrically nonlinear effect using the finite element method for S5400-narutal rubber bonded structures. In case of large deformation problems for two dimensional model, the Green-Lagrange strain is generally employed. In this study, at first we compared the difference solutions obtained between small and large deformations using a cantilever beam model. Subsequently, the stress analysis for the SS400-natural rubber bonded structures using the delamination force obtained from delamination test was carried out. Delamination test was carried out for SS400 and natural rubber single lap joint by changing the adhesive width. Finally, the intensity of stress singularity obtained from large deformation analysis were evaluated in case of several computational models by changing the adhesive width.

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Hysteresis loss plays an important role in rubber friction, which depends on surface and rubber properties. In this study, we conduct friction tests with carbon-filled rubber on dry and wet surfaces under a constant load. We estimate the friction coefficients attributed to hysteresis loss, applying Persson's theory. Based on the estimations, we then discuss about how hysteresis loss and another factors such as adhesion might affect the measured friction in the various range of sliding velocities.

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We propose a method to characterize an undeformed double-layer strand with excess twist moment by considering the deviation from the self-equilibrium configuration where torque is balanced without any external forces. The excess twist gives a measure of the effective torsional rigidity of the strand, determined by the geometrical, material and mechanical parameters from the microstructural viewpoint. Then, we show that quantifying the residual twist moment can successfully identify the fatigue life of specific (3+8)-glass strands embedded in a rubber matrix under cyclic bending.

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In order to evaluate stress distribution of the parts of machinery, infrared stress measurement using thermography is expected to be effective, because 2-dimensional stress information can be obtained in a non-contact with the measured parts. The parts of the machinery often have complicated shape, so the out-of-pale bending could be generated. However, in case of out-of plane bending, the precision of infrared stress measurement becomes lower. In this report, the precision of infrared stress measurement in case of pure out-of-plane bending is investigated with experimental method. As the result, it is found that the precision of the infrared stress measurement can be formulated with Fourier modulus, and that infrared stress measurement result can be modified using phase shift information in case of pure out-of-plane bending.

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In the 1^<st> report, infrared stress measurement under pure out-of-plane bending was investigated. However, in actual parts of machinery, out-of-plane bending and axial loading are mixed, so the infrared stress measurement under mixed loading should be investigated. Then, in this report, heat transfer behavior under mixed loading is calculated and stress measurement results are found to be modified using phase shift. Furthermore, by separating stress into out-of-plane bending and axial component, the stress distribution is on the surface of opposite side found to be estimated.

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The fatigue limit of metal is dicided by 10^7 cycles fatigue test, and it takes long time and costs. Recently, fatigue limit estimation based on energy dissipation has been attracting. In this method, temperture change due to irreversible energy dissipation is measured by the infrared thermography for various levels of stress amplitude. In this study, this method was applied to extruded AZ31B magnesium alloy. It was found that harmonic vibration stress from fatigue testing machine affects the measurement of dissipated energy. This effect can be suppressed by adjustment of fatigue testing machine. New estimation scheme which is based on the incresing rate of dissipated energy was applied. The estimated fatigue limit obtained by the new estimation scheme coinceies with the compressive yield stress.

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It is desirable to evaluate the fatigue limit of commercial products in order to ensure the appropriateness of fatigue design. However, fatigue testing of real products is very difficult to conduct because it requires huge cost, namely a large number of loading cycles using many specimens. In order to overcome such difficulty, the rapid evaluation technique using infrared thermography has been developed and paid attention recently. Unfortunately, the technique has not been established very well yet, especially in the aspect of data processing to determine the fatigue limit appropriately. In this research, data processing techniques were investigated in detail to determine the fatigue limit for type 304 stainless steel specimens with various notches. As a result, a series of data processing techniques which dose not require human judgement has been established for rapid evaluation of the fatigue limit using infrared thermography.

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Fatigue limit estimation based on the dissipated energy measurement using infrared thermography has been getting an attention in various industries. In this study, phase information of temperature change due to energy dissipation was used for accuracy improvement of dissipated energy measurement which is called phase lock-in method. Fatigue limit estimation using phase lock-in method for dissipated energy measurement was conducted for pre-strained JIS type 316L austenitic steel specimen. It is found that the increasing rate of dissipated energy near fatigue limit for pre-strained specimen is smaller than that for as-received specimen. The estimated value of fatigue limit obtained from new estimation scheme coincides with that obtained from conventional fatigue test.

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Lithium ion battery is generally used in mobile devices for its advantages such as easy downsizing and weight saving due to high energy density. If there is short circuit point in the battery, the abnormal heating will occur because of the high energy density. Therefore, it is necessary to identify the short circuit part in Lithium ion battery. In this study, a new technique of nondestructive detection of short circuit part has been developed by using inverse analysis of current density from the magnetic field around the battery. In the previous study, detection of the point short circuit as a micro short circuit was discussed. However, in the case of a short circuit with length such as the linear short circuit, it is thought that detection of the short circuit becomes difficult because the current density flowing into the short circuit is relatively lower and the induced magnetic flux density is also lower. In this report, the numerical and the inspection experiments were carried out using the specimen with linear short circuit. From the obtained result the effectiveness of the proposed technique and its detection limit of the short circuit length in the proposed technique were discussed.

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Recently, the decision of the appropriate time to replace the pipe is becoming important because of an accident prevention and a long life of industrial structures etc. Therefore, techniques of identification of location and thickness of pipe wall thinning is necessary. In this study, a new technique of nondestructive identification of location and thickness of pipe wall thinning has been developed by using inverse analysis of electromagnetic field. For the technique, the location and thickness of the thinning are estimated from measured magnetic flux density when an electric current is applied to the surface of pipe. Furthermore, the sensitivity for the magnetic flux density is improved by using high magnetic permeability material. In order to verify the validity of the proposed technique, measurement experiments were performed by using the grooved plate specimens that imitate a thinning part of the pipe.

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THz electromagnetic wave has been receiving increasing attention in many engineering applications because of the following characteristics. THz wave transmits many kinds of materials except for metals and water. Materials have their own fingerprint absorption spectrum. THz wave is safe for human body. Especially the transmission property of THz wave enables us to develop nondestructive inspection technique for engineering plastics. In this study, fundamental study on defect imaging for Nylon resin sample with various shaped defects was conducted. Terahertz time-domain spectroscopy (THz-TDS) system was employed for the THz scanning imaging.

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Carbon fiber reinforced thermoplastic (CFRTP) has high specific strength, rigidity and corrosion proof CFRTP is used for structural members such as aircrafts, automobiles, blades of electric-generating windmills and sporting goods. Because the mechanical strength of CFRTP depends on the volume fraction, the evaluation of the volume fraction of CFRTP is very important in quality control and a guarantee of quality. Thus, the nondestructive inspection method to detect the volume fraction in CFRTP is required. In this paper, we measured the conductivity of CFRTP from the reply of the reflection wave of the microwave. And using a theory model, the volume fraction was evaluated from the conductivity. As the result, the potential of microwave inspection to evaluate the volume fraction in CFRTP was presented.

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Cast iron with inner mortal coat pipe is the most important and popular component in Japanese main water supply system. However these pipes are difficult to monitor the corrosion loss in thickness because of the lack of a nondestructive testing method. For example, the large acoustic attenuation for damaged mortal and cast iron cause the SN ratio in measurement worse. In this study, we have developed the special wideband ultrasonic transducer and also developed the effective high voltage new ultrasonic pulser for the monitoring of the corrosion loss in thickness for aging cast iron with inner mortal coat pipe. Accuracy for this measurement system for thickness sizing and the repeatability of back surface reflection echo were also investigated.

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In this study, the nonlinear behavior of Lamb waves at contacting edges of linear elastic plates is investigated by the perturbation analysis using the hybrid finite element method. The contacting surfaces are modeled as a nonlinear spring interface, which takes into account quadratic nonlinearity. For the incidence of the lowest-order symmetric (SO) Lamb mode, the amplitude reflection and transmission coefficients of the SO mode, which are obtained by linear analysis, vary monotonically with the incident frequency. Due to the nonlinear interaction of the incident SO mode with the contacting interface, the double-frequency SO mode is generated. The amplitude of the generated second-harmonic SO mode has a sharp peak at the half of the resonance frequency of the contacting interface.

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Subharmonic ultrasound technique has been expected to improve the conventional ultrasonic inspection especially for SN ratio in crack tip echo measurement. We have developed a SPACE (Subharmonic Phased Array for Crack Evaluation) system and have confirmed the advantage for some industrial cracks inspection. In this study, we planned to observe subharmonic wave generation behavior with varied combinations of the crack openings and the amplitudes of incident ultrasound to investigate the mechanism of subharmonic wave at crack. For this purpose, we improved the angle transducer and ultrasonic pulser to increase the incident ultrasonic amplitude. The closed fatigue crack specimens were prepared and basic subharmonic behaviors were observed using the improved SPACE system by changing the applied slight load to control the crack opening and the incident ultrasonic amplitude.

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Water immersion ultrasonic imaging system using reflection echo from de-bonding interface have been widely used for composite materials and IC products and so on. However recently, some types of the interface so-called kissing bond with tightly closed de-bonding have appeared in several industrial products and the detection of the kissing bond is difficult to detect because ultrasound transmit the interface of kissing bond. On the other hand, we have developed new ultrasound inspection system of SPACE for tightly closed crack evaluation system using ultrasonic subharmonic imaging. Thus we have also developed water immersing subharmonic imaging system as an industrial interface evaluation system with a commercial acoustic lens. But since the large displacement ultrasound is required for subharmonic wave generation, we developed a high voltage and high-frequency acoustic lens in this study and the availability for an evaluation of the kissing bond with the new large displacement ultrasound subharmonic imaging system was investigated.

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When cavitation occurs and bubbles collapses in fluid machinery, such as pumps, impact loading due to the bubble collapsing shortens the life time and decreases the performance. Recently, inspection of cavitation-erosion damage inside the pumps has been conducted by direct visual observations after stopping the operation temporarily. In this study, to realize damage monitoring remotely from outside of the machinery, impact load by spark-generated bubble collapse was estimated using inverse analysis. Impact experiments by spark-generated bubbles were conducted with aluminum plate and impact load and point were measured with AE sensors. The effect of impact point in measurement of impact load was confirmed by bubble collapses at different impact points.

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Acoustic Emission Testing (AT) is one of the non-destructive testing methods which are widely used in engineering fields. Final goal of monitoring AE phenomena is to estimate characteristics of AE sources and to provide beneficial information to prevent fatal fracture. It is know that b-value is not changed by propagation length from the AE sources to AE sensors. Although, the effects of the frequency dependence on AE attenuation to b-value is not discussed in details by any researcher. In this research, we conducted the simulation with two conditions. First condition assumes AE source contains single frequency of 45 or 65 kHz, and the other condition assumes the source composed of 25 kHz, 45 kHz and 65 kHz. As a results, b-value is changed by propagation length when assuming AE sources with multiple frequencies. The cause of changing b-value is due to non-linear behavior of AE attenuation.

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This paper overviews our developments of a distributed optical fiber sensing technology, which is the BOCDA (Brillouin Optical Correlation Domain Analysis), for aircraft SHM (Structural Health Monitoring). In order to verify the reliability and durability of the BOCDA-SHM system, fatigue tests using Aluminum specimens were conducted. Strain data measured by the system and conventional strain gages were compared with each other. Furthermore, durability tests simulating actual flight conditions were also conducted such as temperature variation and humidity. As the results of the tests, the authors convinced that the reliability and durability of the system are enough to be used in actual flights.

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This paper introduces a new technique to reconstruct Lamb wave ultrasonic tomography with manual transmitter scanning. By this technique, ultrasonic tomographic image can be obtained using only 4 receivers and 1 transmitter without a scanner or an encoder. The image is reconstructed by determining the transmitter position (x,y) by source location method and estimating an existence of defects between the transmitter and the receivers from amplitude-ratio of Ao mode to So mode of lamb wave. Lamb wave tomographic image was successfully reconstructed for an Aluminum plate with artificial defects by proposed method.

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Adhesive joints are widely used in wide industrial fields, supplementing or replacing traditional joining technologies. However, a mismatch due to different materials properties may cause stress singularity at the edge of an interface between the materials, which causes debonding of structures. Since few studies are available for evaluating the bonded strength, this study focuses on the solutions for the intensity of the singular stress for the semi-infinite butt joint. In this research, an effective numerical method combined with FEM results is used to obtain the SIFs at corner of adhesive joints in arbitrary material combinations. Here, the solution of bonded plate, which has already been solved accurately in the previous study, is used as the reference problem. In this paper, the effect of adhesive thickness on the intensity of singular stress will be analyzed, also the effects of material combination on the intensity of singular stress at the end of the adhesive with thin layer in a semi-infinite plate will be discussed.

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In this paper, an intensity of singular stress field for a bonded cylinder under a bending load is calculated. The analytical method focuses on the stress values at the interface corner edge obtained by performing FE analyses on the unknown and reference models which are subdivided by the same mesh pattern. Then the debonding fracture criteria are examined in terms of the intensity of the singular stress appearing at the corner of butt joints by using the previous results of four-point bending experiments.

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Advanced semiconductor products have structures with thickness and width in nanoscale. As the size of structures reduces to a nanometer level, a ratio of their surface to volume increase. In the present study, three-layered structure is analyzed using molecular dynamics (MD) method and the anisotropic elasticity theory. The analysis of stress and displacement near interface misfit dislocation in a two-phase anisotropic body is considering interface stress and interface elasticity. The stress and displacement distribution at the interface are compared the analysis considering the interface properties and the MD method.

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Singular electric displacement fields occur at the vertex of the interface in piezoelectric material joint under mechanical or electrical loadings. This means that a large electric displacement occurs arround a singular point. Concentrated electric displacement is useful for engineering and characteristics of electric singularity should be further investigated. In the present study, some characteristics of singular electric displacement fields in a piezoelectric material joint are investigated using 3-dimensional finite element analysis. Stress and electric displacement fields around singular point are analysed in detail and influences of loading conditions and geometric factors on the singular fields are discussed.

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In the present study, the conservative integral formulation is developed for calculated the intensity of singularity at a vertex of the interface in three-dimensional piezoelectric dissimilar material joints. The model applied mechanical load is considered. In order to investigate the influence of integral area on the accuracy of the results, models with various integral areas are used. Finally, distributions of stresses are compared with the FEM results, in which using a model with extremely refined meshes near the singular point.

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The asymptotic solution of the singular stress around a three dimensional corner between dissimilar materials was analyzed using the H-integral method. However, we could not obtain the accurate scalar parameters of asymptotic solution for some problems. In this study, we investigated what reduced the accuracy of the solution and how to improve the accuracy. The eigen values and eigen vectors of the asymptotic solution was analyzed by the eigenvalue decomposition of the finite element model of a corner. After that we analyzed a target problem using the elastic finite element method, and performed the H-integral to obtain the scalar parameters. We found out that the some integral equations related with the H-integral, which should be zero, were not zero when we obtained inaccurate scalar parameters. The integral values decrease with refining the finite element meshes for the eigenvalue decomposition, and the obtained scalar parameters approached constant values. The eigenvalue decomposition demanded very fine finite element meshes to obtain the accurate values for some problems.

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In this paper, thermoelectroelastic fracture behavior of a functionally graded piezoelectric laminate with a crack normal to the bimaterial interface under transient thermal loadings is considered. It is assumed that the thermoelectroelastic properties of the functionally graded piezoelectric plate vary continuously along the thickness of the plate, and that the crack faces are supposed to be completely insulated. By using the Fourier transform, the thermo-electro-mechanical problem is reduced to a singular integral equation, which is solved numerically. Numerical calculations are carried out, and detailed results are presented to illustrate the influence of the geometric and material parameters on the stress intensity factors.

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This paper deals with the effect of adhesion layer on the stress intensity factor for small edge interface crack in bonded plates under bending. In this study, the stress intensity factors of the small edge interface crack are analyzed by the crack tip stress method with varying the crack length, adhesive thickness and material combination. The stress intensity factor of the edge interface crack is controlled by the singular stress field at the interface free edge in butt joint without the crack when the crack is very small. The calculation shows that the normalized stress intensity factors of the small edge interface crack under bending are related to the intensity K_σ and the singularity index λ_<12> of the interface edge at the interface edge without the crack. Then, it is found that the normalized stress intensity factors can be expressed as K_1+iK_2=(F_1+iF_2)K_σa^<λ_<12>-0.5> √<π>(1+2iε) and the parameters F_1 and F_2 are constant values when a/h<10^<-2> irrespective of the adhesive thickness and the loading conditions.

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This paper deals with the analysis of the thermal stress intensity factor for small edge interfacial crack between a bonded dissimilar plates subjected to uniform change of temperature by using the crack tip stress method. In this study, the small edge interface crack problem under thermal stress is solved by superposing the uniaxial tension problem with edge singularity and the uniform stress problem having the boundary condition of temperature change and uniaxial compression. The calculation shows that the stress intensity factors of the small edge interface crack under thermal stress can be evaluated from four factors related only to the Dundurs' parameters a and fl. The failure strength is considered for butt joints subjected to a combination of thermal and mechanical loading, based on the critical value of stress intensity factor for small edge interface crack.

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In this study, fracture process of friction stir welded A1100/Zn plated steel dissimilar materials joint was investigated by conducting in-situ observation tensile shear strength test. In case of the joint with higher strength, plastic deformation of A1100 and crack propagation into A1100 was observed. In case of the joint with lower strength, crack propagated along the interface of intermetallic phase. Change in mechanical property of A1100 due to addition of Zn and intermetallic phase formed affect the fracture process and the joint strength.

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Dissimilar material joint makes a machine light and efficient. Welding is widely used to connect dissimilar materials, but an intermetallic compound produced in the interface and stress specificity at interface end are concerned to decrease the joint strength. It is important to evaluate the strength of welded joint for designing machine and structure. In this study, single lap specimens with welding joint of Fe and Al plates were prepared for a tensile shear test and a fatigue test. Joint strength and interfacial strength were investigated by modifying shape of welding joint. Fracture analysis revealed the interface was brittleness destruction and the joint strength depends on the strength of the starting point of the destruction. Fatigue curve can be classified every destruction form by using the hotspot stress of the starting point of the destruction.

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Structural failures due to thermal transient loads and seismic ones are complicated multi-physics phenomena with many uncertain factors. Therefor conservative evaluation methods were applied to both loadings and strength for design. However, best estimation with uncertainty evaluation are suitable for trouble shootings and risk analyses. To satisfy above requirements, total evaluations of loadings and strength by multi-physics simulation are desired. In the case of thermal transient and seismic loads, dynamically coupled analyses are required. Unified uncertainty analyses are also needed for loadings and strength uncertainties.

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This study has applied the Bayesian updating scheme and the stochastic finite element method (SFEM) to the Load and Resistance Factor Design (LRFD) method of a round bar having random geometry. The LRFD method is able to take into account separately the stochastic variability in material strength, in geometrical randomness of structural components and in loads applied to the components. Therefore, this method makes it possible to keep up the reliability of the components during the period of use. The LRFD method, however, has a problem that it requires vast amount of data for performing the design. Addressing this problem, in this study, the Bayesian updating scheme, which requires only small amount of data, has been applied to the LRFD method. The SFEM and the Markov chain Monte Carlo (MCMC) method have been adopted in this study to analyze the stochastic variability in component geometry as well as in loads and to perform the Bayesian updating, respectively in the LRFD.

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Design extension conditions (DEC) induce some different failure modes from design conditions. Furthermore, the best estimation for these failure modes is required for preparing countermeasures and management. Therefore, this study focused on identification failure modes under DEC. To realize best estimation, it is prerequisite to clarify failure modes with ultimate structural strength under extreme loadings such as very high temperature and pressure. In this paper, relations between failure modes and extreme loadings were investigated by the numerical simulation using the cylindrical model of lower formed head of reactor pressure vessel.

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Identification of operational loads is useful and applicable not only to the structural design and structural integrity management but also to the active control of the internal loads. The aerodynamic loads are continuously distributed over the aircraft wing and consequently the author's group has been developing a flexible method for interpolating the distributed load to identify the full-field aerodynamic load based on the inverse analysis. The present article reviews the numerical results and application to the wind tunnel tests. Also presented is the coupled inverse analysis of the aerodynamics and elasticity. Attention is paid on the regularization method which is inevitable in order to reduce the adverse effects of measurement error.

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[in Japanese]

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The object of this study is to investigate the mechanism of environmental effects on low cycle fatigue crack growth of SUS316. Low cycle fatigue test and periodical observation on inner surface of a hollow specimen was conducted by developing new type of replica observation. The crack growth in PWR environment was measured and the investigation of environmental effects on crack growth was conducted. Crack initiation rate of fatigue test in PWR environment is faster than in air condition. Consideration of crack initiation in earlier period of fatigue test, acceleration of crack growth rates, coalescence of cracks due to high density of cracks generated in early stage of cycles is necessary to quantify environmental effects on fatigue life.

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High cycle thermal fatigue may occur in components and piping systems of sodium-cooled fast reactors (SFRs) where fluids at different temperature are mixed. A prototype coupling method consisting of the fluid-structure thermal interaction simulation code MUGTHES and the structural thermal stress analysis code FINAS with interface program MUFIN has been developed in order to estimate the thermal fatigue in the SFRs. As a fundamental validation of the coupled method, it was applied to the water experiment for thermal mixing phenomena in a T-junction piping system. In the experiment, thermal interaction between the fluid and the structure made of aluminum installed to the branch pipe side wall was considered. Through the numerical simulations, applicability of the coupled method was confirmed.

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Thermal fatigue cracking may initiate at a tee pipe where high and low temperature fluids flow in. The mixing flow causes temperature fluctuation near the pipe wall and may result in fatigue crack initiation. In this paper, characteristics of the wall temperature and thermal stress fluctuation at a mixing tee were investigated by tests, in which wall temperature was measured with 148 thermocouples. Then, the thermal stress fluctuation was estimated by finite element analysis based on the measured wall temperatures. The range of the stress and temperature fluctuations became large locally on the main pipe inner surface. The maximum stress fluctuation range obtained by this test was about 0.21 times the value of the term Eα(T_b-T_m)/(1-ν), where T_b and T_m are the fluid temperatures at the inlet of the branch and main pipes, respectively.

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Behavior of small crack propagation during creep was studied by means of a hollow specimen with a simulated cooling notch, on the basis of non-linear fracture mechanics approach. Through the work special attention is paid to understand (i) microstructural aspects on the propagation behavior of the small creep crack interacting with grain boundaries and dendritic boundaries, (ii) difference between small cracks and physically long cracks, (iii) role(s) of stress concentration and its relaxation with creep time, and (iv) role of thermal gradient.

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Studies of crack growth under equi-biaxial fatigue which is caused by thermal stress have been conducted and show that crack growth rate under equi-biaxial stress is faster than under uniaxial one. This study focuses on the difference of crack growth rate between equi-biaxial and uniaxial and compared them quantitatively based on fatigue life and crack growth rate. Then the mechanism of occurrence of different crack growth rate between them is examined. The acceleration of crack growth rate under equi-biaxial stress is estimated as the main reason to decrease fatigue life.

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