In order to investigate the failure modes of piping systems under excessive seismic loads, a series of shaking table tests on elbow pipe specimens has been conducted. In the experiment, steel pipe elbows and lead pipe elbows were used as the specimens. Obtained failure modes are classified into following three modes; 1) fatigue failure, 2) ratchet-collapse, and 3) large deformation. From the experiments and a lot of preceding studies, the most possible failure mode would be the fatigue failure. Under some extreme conditions, such as large primary stress was caused by the deadweight, ratchet-collapse or large deformation would occur. It seems that the direction of the gravity affects a lot on the occurrence of the ratchet-collapse. The primary stress level would also be an important factor. But other factors to dominate failure behavior are still not clear, so further experimental or analytical studies are necessary.

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As a failure mode which can occur in structures under seismic loading, progressive deformation can be considered. However the mechanism of it is not clear. In this research, focusing on similarity between thermal loading and seismic loading, vibration experiment was conducted in order to clarify occurrence condition of progressive deformation caused by seismic loading. As a result, under vibration loading whose frequency is high which has characteristic of secondary loading, it was clarified that the occurrence condition can be evaluated with combination of primary loading, gravity weight, and vibration loading like that of thermal ratchet. On the other hand, as vibration loading whose frequency is low has characteristic of primary loading, the occurrence condition is not similar to that of thermal ratchet. In terms of material, occurrence condition can be evaluated regardless of difference of material by standardization with yield stress.

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Validity of the strain intensify factor for predicting the fatigue crack growth under a large cyclic loading simulating seismic loading was investigated by fatigue crack growth tests using SUS316 stainless steel and S45C carbon steel. The plate specimens were subjected to fully reverse load-controlled cyclic load up to nominal stress amplitude of 350 MPa. The obtained crack growth rate was more than 0.2 mm per cycle, which was larger than the critical ductile crack growth length defined for fracture toughness tests. It was shown that the crack growth rate correlated well with the effective strain intensify factor range under such large loading condition. It was true not only for the stainless steel but also for the carbon steel.

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Inelastic analyses using advanced constitutive models are expected to clarify failure mechanisms of piping structures under excessive seismic loading. A multilayer kinematic hardening model for cyclic plasticity is presented for carbon steel pipe, with a set of standard stress-strain properties. The model can express the nonlinearity of stress-strain relations as well as cyclic hardening of the material. Finite element large deformation elastic-plastic analyses with this model are conducted for the JSME piping benchmark problems.

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In recent years, the demand for artificial joints has increased. In Japan, aging is in progress. Therefore, it is necessary to increase the lifespan of artificial joints. The purpose of this study is to study the effects of surface texturing, that is a technique of pattering a fine processing of the surface on the frictional behavior and the corrosion reaction of titanium materials that is widely sued in artificial joints. Titanium and its alloys have excellent corrosion resistance while possesses low wear resistance. The materials used were pure titanium and Ti-6Al-4V alloy. The texturing to the specimen surface was achieved by applying parallel grooves of about 1mm depth. The pitches of the grooves were changed. Friction and corrosion tests were performed in physiological saline to simulate the conditions in which artificial joints are used. The surface textured specimens maintained the corrosion resistance. Abrasion resistant improvement was seen by narrowing the pitch of the parallel grooves. Wear properties were improved by narrowing the pitch of the parallel grooves. However, wear properties of textured surface was lower than that of the polished surface. The design of the texturing has to be examined to improve the wear characteristics of titanium and its alloys.

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Bone fracture treatments has been increasing with the number of bone fracture patients because of the aging society. Bioabsorbable bone fixation devices are required to improve quality of life of patients. Poly(lactic acid) which has high level of biocompatibility has attracted much attention as material of the device. However, applications of PLA bone fixation device are limited to low loaded region, because of their lower mechanical characteristics. As a method to improve mechanical properties of PLA, drawing has been developed. In this study, optimum molding conditions are investigated to improve mechanical properties of PLA. Deformation behavior of PLA rods in drawing was simulated through finite element method. Orientation in the rods was estimated from principal strain caused during drawing. As a result, orientation function which was calculated from the strain after extrusion showed good agreement with the experimental values.

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In this study, three different porous structures, namely, lattice, truss and honeycomb, were designed using a 3-D CAD softwear, and then constructed using a 3-D printing machine with a thermoplastic polymer PMMA. These porous structures are supposed to be used as load bearing frame structures in bone tissue engineering. Compressive mechanical properties were measured and compared to understand the effects of the porous structures on the properties. Fracture morphology was also examined using FE-SEM to characterize the fracture mechanisms.

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The tissue engineering and regenerative medicine have received a lot of attention. In this field, cells and scaffolds are important both ex vivo as well as in vivo. From the view point of effective treatment, in addition to histological feature, the compatibility of mechanical properties is also important. In this study, the dynamic and static compressive properties of bovine articular cartilage-cancellous bone layered tissue were measured using a universal testing machine and a split Hopkinson pressure bar method.

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In this study, the fundamental properties such as microstructure and compressive modulus were examined using human femoral heads with osteonecrosis, and compared with the properties of healthy tissues. A finite element model of a hip joint with an artificial elliptical osteonecrosis model was then constructed from CT images of an old female patient. It was found that collapse of the femoral head can be well predicted using the FE model with osteonecrosis at a projection position.

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Bone is often regarded as a composite material consisting of mineral particles and organic matrix (mostly Type I collagen) on a microscopic scale. The mechanical properties of bone tissues at a macroscopic scale depend on the structural organization and properties of constituents in the microscopic scale. However, both mechanical behaviors of mineral and collagen phases are not clear yet. In this study, both microscopic strain of collagen and mineral phases in cortical bone by using small and wide angle X-ray diffraction, respectively. The collagen matrix strain allowed tensile deformation as compared with mineral phase. This study could suggest that macroscopic mechanical properties of bone tissue depend on the degree of deformation of mineral and collagen matrix.

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We are aiming to control the osteoclastic metabolic behavior by the material design of substrates, in order to accelerate the absorption of scaffolds for bone regeneration. We hypothesized that the metabolic behavior of osteoclasts would activate with increasing elastic modulus of substrates. The purpose of this study is to demonstrate this hypothesis by comparing the metabolic behavior of osteoclasts on substrates with different elastic modulus. Here, hematopoietic stem cells were cultured and differentiated into osteoclasts on PCL substrates. The elastic modulus of PCL substrates was controlled as 0.295 GPa, 0.406 GPa and 0.657 GPa by changing cooling rate as rapid cooling, slow cooling and cooling in furnace, respectively. The metabolic behavior of osteoclasts was observed by fluorescence imaging of cathepsin K. As results, activation ratio of osteoclasts was 36.5 %, 57.4 % and 62.5 % on rapidly cooled, slowly cooled and furnace-cooled PCL substrate, respectively. Thus, it can be verified that the increase in substrate elastic modulus induces the activation of osteoclastic metabolic behavior.

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It has been reported that cells on elastic substrate aligned at a particular angle so as to minimize their strain magnitude caused by cyclic deformation of the substrate. However, little is known about the mechanism of their alignment. In this study, we investigated the effects of intercellular junctions on the cell alignment in MC3T3-E1 osteoblast-like cells. The cells were cultured on silicone membranes under a sparse (20 cells/mm^2) or dense (500 cells/mm^2) condition, and subjected to cyclic uniaxial stretch for 24 h. Alignment of their actin cytoskeleton were then analyzed with a two-dimensional fast Fourier transformation analysis. In the sparse condition, actin cytoskeletons aligned mostly in the direction in which normal strain of substrate becomes zero (50°-60°). In the dense condition, in which cell tissues have intercellular junctions, actin cytoskeletons aligned in perpendicular to the stretch direction, as if the cells avoided shear deformation causing breakdown of cell-cell junctions. We further examined the alignment behavior in the cells whose actin-nucleus connection was inhibited, and found that their alignment was disturbed by the lack of actin-nucleus connection. These results indicate that intercellular junctions as well as actin-nucleus connection may have profound effects on cell tissue reorganization processes in MC3T3-E1 cells.

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Prolonged bed rest may cause pressure ulcer. Microvascular circulation in the soft tissues at bone prominence tends to be obstructed not only by compression through body pressure but also by shear through slip motion between the mattress and the body. In this study we formulated kinematic relations of the skin by taking account of compression and simple shear. We analyzed two cases: a case with a stress-free condition in a horizontal direction under the first loading process of compression and a case with a deformation constraint in the same horizontal direction. We assumed that the deformation was restricted under shear deformation. Results of principal stretches of the skin model under combined deformations of compression and shear showed that the effect of shear was equivalent to that of compression in the latter case. Results of principal stretches for the former case showed that the transverse deformation was larger with a combination of compression and shear than the deformation of compression only.

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Optimization of hydrogen embrittlement is needed to develop the next-generation of high-strength aluminum alloy. The existence of hydrogen pores cannot be neglected in the hydrogen embrittlement of aluminum alloys. Owing to separate and understand the effect of hydrogen in the matrix and hydrogen micropores, it is required that assessments of model material, which is drawn a sharp distinction between with/without hydrogen and with/without micropores. In the present study, 3D/4D imaging is employed to evaluate/produce model materials, and the principle to optimize the hydrogen embrittlement of aluminum alloys are suggested.

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Recently, Toda et al. have performed X-ray microtomography using synchrotron radiation to observe the ductile fracture process of a 2024 aluminum alloy, revealing that the ductile fracture in its material does not occur through a conventional ductile fracture process (i.e. growth and coalescence of voids nucleated at inclusions/particles) but through the simple catastrophic linkage of hydrogen pores. Hence, if one is able to control the size/shape/distribution of those hydrogen pores, it is highly possible for an aluminum alloy to attain an unprecedented high-ductility. We therefore attempt to find an optimum microstructure through R4ME, pursuing a ductile aluminum alloy.

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In this study, a finite element model of a femur with a THA stem was developed using CT images of an old female patient. Damage analysis was then performed under different boundary conditions imitating different daily motions that may cause incident bone fracture. A damage theory was introduced to predict tensile and compressive fracture and also compressive yielding of elements. The FEA results exhibited that the Vancouver classification of bone fracture associated with THA can be predicted by CT-FEA with the damage theory.

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In rolling contact fatigue (RCF), cracks initiate and propagate from inclusions beneath the surface. In the present study, crack propagation behavior under RCF was observed by synchrotron radiation computed laminography (SRCL), which is suitable for thin plates, in SPring-8 (Super Photon Ring-8 GeV). Specially fabricated inclusion-rich steel (modified JIS SUJ2) plate specimen, which includes extended inclusions distributed in depth direction, was employed in the experiments. Specimen with surface crack from inclusion and after the occurrence of flaking was observed by SRCL, and flaking defect and crack under the surface was successfully detected. It was found that the tensile-type vertical crack, which was perpendicular to the rolling contact surface, was formed from a cylindrical inclusion. After the vertical crack propagated along inclusion, the shear-type horizontal crack, which was parallel to the rolling contact surface, was found to initiate and then flaking occurred as the result of the propagation of the shear-type crack. It is considered that the vertical crack is an important factor of flaking process and crack propagation behavior under RCF from inclusions is clarified by SRCL.

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Porous aluminum has lightweight and high energy absorption properties. In this study, sandwich panel consisting of ADC12 porous Al and A1050 Al plate was fabricated by friction stir processing (FSP) route. The bending properties and deformation behavior of the sandwich panel was obtained by the bending test. It was shown that crack occurred in porous aluminum, then spread to A1050 Al plate.

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Open-cell porous aluminum (Al) was fabricated by friction powder sintering process. In this process, a mixture of Al powder, ADC12 Al alloy powder and sodium chloride (NaCl) powder as spacer particle was used as starting materials. The powder mixture was sintered only by rotating tool plunged into the mixture. NaCl was removed by placing the sintered mixture in water, and pores were formed. In this study, strength of porous Al were improved by ADC12 Al alloy powder addition.

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Accuracy and availability of voxel finite element was examined for the large-scale image-based modeling in elastic and elastic-plastic analyses. The voxel modeling is easy and robust to generate a finite element mesh with highly complicated geometries, while the irregular stress appears on the zigzag surface. To reduce this irregular stress, we employs a stress-smoothing filter as a post-process. Through an example concerning a stress concentration around a spherical cavity, the convergency with respect to the element size and the stress-smoothing ability was examined in the elastic analysis. Moreover, two types of materials, that is, high strain-hardening and low strain-hardening aluminum alloys, were compared in the elastic-plastic and large-strain analysis. We found that in case of low strain-hardening material, the effect of the irregular stress is reasonably negligible.

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The crack initiation mechanism of cast aluminum alloys is addressed through the image-based finite element analysis. By using the synchrotron radiation CT, the initiation and extension of fatigue crack has been observed. The fatigue crack is initiated by the break of silicon particles near the pores, while its mechanism is not clear. To understand the stress and strain fields around silicon particles under cyclic loading, the finite element elasto-plastic finite-strain analyses were carried out. From the fatigue test and its in situ CT observation, the broken and unbroken silicon particles were identified. Their finite element models were semi-automatically generated from the initial CT image, where a few tens of silicon particles were included. By comparing the history of stress and strain between broken and unbroken silicon particles, we examined the trigger of breakage of silicon particle, that is, the cause of crack initiation.

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The effect of morphological properties of Si particles on the fatigue strength of cast aluminum alloy was investigated. The low-cycle fatigue test was carried out with the in situ observation by the synchrotron radiation CT. From the chronological image data, some silicon particles broken during the fatigue test were identified, and the surrounding small image centered by the broken particle was cut from the initial CT image. The volume, principal radii, aspect ratio, and inclination angle were calculated on the voxel count basis for all particles included in the cut image. The correlation between the broken particle and the neighbor particles was also evaluated. The larger particles tended to break faster in principle. However, the inclination angle and the effect of neighbor particles considerably affected to the break of silicon particle. In case of early break particle, the correlation between the parameters were relatively strong, and vice versa. So, the large particle nearly parallel to the tensile axis easy to break with the assist of neighbor particles of similar shape and angle.

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In this study, advanced repairing technology based upon High Velocity Oxy-Fuel (HVOF) spraying technique, which would be replaced with typical weldment technique, has been interested. Thus, the purpose of this study is to show adhesion strength of the component repaired by HVOF spray technique in comparison with other spraying technology. In order to achieve this purpose, tensile test was conducted for Type 304 stainless steel plate-shaped sample repaired with semi-elliptical shape. Influence of the aspect ratio of the elliptical shape on tensile strength of the repaired part was discussed through continuous CMOS observation, image-based analysis and finite element analysis. As a result, it was found that the critical strain was increased as the aspect ratio changes, which means that the slender repaired shape normal to crack surface is desired to improve effectively adhesion strength of the repairing interface. It was also shown that the results of three-dimensional finite element analysis involving glue option connecting the interface and residual stress was matched completely with that of the image-based strain analysis, which allows us the optimum decision how we cut off actual damaged component.

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In this paper, mechanical properties and microstructure of Type CF-3M cast austenitic stainless steel (CASS) aged at 573-723K for up to 15000 h were investigated using atom probe tomography, Charpy impact test and hardness test in order to evaluate the relationship between microstructure and mechanical properties. As a result, it was found that estimation of Charpy absorbed energy of the CASS was difficult using only Variation, which is a parameter of the ferrite phase decomposition.

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Japan has the special feature that there are a lot of natural disasters compared with other country. The volcanic explosion at Mt Fuji has been paid attention recently. If aerosol-like volcanic ash is inhaled from the air intake in those land-based gas turbines, all generators would be stopped and then a blackout would be occurred in the whole Kanto area. In this study, deposition behavior of volcanic ash under a high-temperature gas flow was examined. In order to achieve this purpose, the volcanic ash deposit simulator, which can simulate a combustion flow, was developed. Subsequently, the volcanic ash deposition test was conducted, and a high-temperature exposure test was also performed for the ash-deposited sample.

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In order to verify the coefficient calibration for the embrittlement correlation method in JEAC 4201-2007/2013, an alternative calibration has been conducted with an optimization algorithm other than that used in the original calibration process. Although the newly obtained coefficient set is not identical to the original set, the values of the objective function and the predicted shifts of the reference temperature are similar in both coefficient sets. It suggests that the original coefficients for JEAC 4201-2007/2013 are appropriately calibrated.

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In recent years, fatigue damage and stress corrosion cracking has become a problem in welded structures because it is difficult to estimate remaining lifetime based on crack propagation prediction. In order to predict the crack growth rate of the observed crack, it is necessary to evaluate three-dimensional residual stresses for the whole structure. The second author has been proposed the nondestructive method based on the eigenstrain methodology to evaluate residual stresses in the thickness direction from residual strains on surface measured by X-ray diffraction. This study aims to demonstrate the effectiveness of the method for an actual ferritic welded plate. To evaluate the estimation accuracy of this method, residual stresses on the bottom surface estimated from residual strains on the top surface are compared with residual stresses on the bottom surface measured by X-ray diffraction. The stability of the solution in the vicinity of the weld line could be improved by using residual strains on the weld metal. However, it is necessary to improve the estimation accuracy, as a future work.

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Considering fatigue crack growth evaluation for multiple transients within the framework of the fitness-for-service, the chronological order of each transient is usually taken into account. In this paper, a general treatment of the multiple transients was proposed in case that the chronological order of the transients was indefinite. And the adequacy of the proposed treatment was validated.

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In order to evaluate fatigue crack propagation behavior at J-welding portions of Bottom Mounted Instrumentation (BMI) in Reactor Pressure Vessel (RPV), crack propagation crossing dissimilar material interface between base metal and clad should be investigated. This paper shows crack propagation analyses of cladded plates under cyclic tension load by XFEM, which can model crack independently of finite elements, as a preliminary study for crack propagation analyses considering cladding interface.

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When the cracks are detected in the nuclear components, structural integrity evaluation should be performed by the Fitness-For-Service Codes (FFS Codes) of the Japan Society of Mechanical Engineers (JSME). The stress intensity factor (SIF) solutions of cracked plate for arbitrary stress distribution was revised in FFS 2012version. The applicability of the SIF to stress corrosion crack growth behavior in Primary Loop Recirculation (PLR) piping was examined. The results show that the SCC crack growth behavior is almost the same. Moreover, by applying the SW solution for the cylinder in the SCC crack growth evaluation of piping, it was confirmed to be a more appropriate evaluation.

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Many stainless steel piping are used in the nuclear power plants. Cracks are identified on the stainless steel piping used in the old plants. LBB (Leak before freak) is one of the integrity evaluations. LBB of cracked piping is important for operating the old plants safely and reasonably. Tensile load is applied to the piping due to high-temperature and high-pressure flow and bending is also applied to the piping due to external force caused by an earthquake. The handling of the load history is not specified in the standard for LBB. SUS304 steel piping with cracks is subjected to bending and tension in arbitrary order. We insestigate the effect of the load history on the crack opening displacement and plastic collapse strength of the piping. Conclusions are as follows: (1) The load history affects the crack opening displacement. (2) The load history do not affect the plastic collapse strength.

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For introducing the elastic-plastic analytical procedure to the seismic safety evaluation of piping systems in nuclear power plants, benchmark analyses based on the existing experimental results have been conducted. The purpose of the benchmark analyses is to clarify the variation of the elastic-plastic analyses results and the factors to cause such analytical variation depending on the analysts. From the benchmark analyses on the in-plane bending test of a carbon steel elbow, the variation of the modeling procedure, the load-deflection curves, strain behavior are obtained. The results of the benchmark analyses show that the yield stress set in the analyses is one important factor to estimate the elastic-plastic behavior well. It is also shown that the variation of the residual strain tend to be large especially under high input level, though the strain range can be estimated well.

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The special task group of the JSME Codes and Standards Committee has planned to make a guideline for excessive cyclic loading of piping. For this purpose, the special task group conducted benchmark analyses to simulate the test results of an elbow pipe under cyclic loading. The authors carried out a finite element analysis and evaluated the fatigue behavior and fatigue life of the elbow pipe under cyclic loading. The following results were obtained. (a) The crack initiation area was successfully predicted by the analyses. (b) The fatigue life of the elbow pipe was predicted conservatively by the analysis based on the prediction curve for piping components proposed by NUPEC and the revised Manson's universal slope method.

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The stress state of elbow and tee pipes is complex and different from those of straight pipes. Manson's universal slope method cannot predict the low-cycle fatigue lives of elbow and tee pipes under cyclic bending and internal pressure conditions. In this work, the authors carried out a finite element analysis for simulating the reported experimental results of elbow and tee pipes. The crack initiation area and the crack growth direction were successfully predicted by the analyses. The analytical results showed that the revised Manson's universal slope method can accurately predict the low-cycle fatigue lives of elbow and tee pipes under internal pressure conditions regardless of shape and dimensions.

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To statistically investigate the changes and the distributions in surface roughness, strain controlled low cycle fatigue tests of austenitic stainless steel were conducted under strain range Δε=8, 4%. During the tests, the specimen's surface topography was regularly measured using a laser scanning microscope. The surface topographies obtained were analyzed by frequency analysis to separate the surface relief due to persistent slip bands. The persistent-slip-bands-induced surface relief evolution was quantitatively evaluated by using arithmetic mean roughness R_a. As a result, R_a at Δε=8, 4% increased with the increase of UF (Usage Factor). The R_a data were plotted roughly linearly on a log-normal probability paper. It suggests that R_a likely follows a log-normal distribution. On the probability papers, the slope of R_a plots and the average value at Δε=8, 4% were clearly different. It shows that the distribution form of R_a varies between different Δε. The slopes of R_a plots at each UF were similar on the paper. It showed that the dispersion of R_a data didnot change even if UF increases.

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The mechanisms of improvement of fatigue limit by portable pneumatic needle-peening (PPP) were investigated for a welded joint specimen of austenitic stainless steel (JIS-SUS316) containing a semi-circular slit at the weld toe. The residual stress near the weld toe was measured before and after PPP. Moreover, finite element analysis was conducted in order to calculate the stress concentration factor of the weld toe before and after PPP. The values of fatigue limit before and after PPP were predicted based on fracture mechanics assuming that the semi-circular slit was equivalent to a semi-circular crack. The prediction results of the fatigue limit and the maximum size of crack that could be rendered harmless by PPP were almost consistent with the experimental results.

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It was reported by the authors that a nitrided layer formed on SUS310S heating tubes in the reactor of melamine production plant showed a severe spalling susceptibility. After replacement to SUS304 heating tubes, spalling and thinning was suppressed. According to the previous studies, phases of the nitrided layers of the SUS310S and SUS304 heating tubes consist mainly of γ' and α', respectively. The reason why the SUS310S heating tube showed the high spalling susceptibility was considered to be a higher expansion rate of γ' compared with α'. The purpose of this study is to investigate the relation between the spalling susceptibility and nitrided layer characteristics (crystal structure, nitrogen concentration). EDX analysis showed a higher nitrogen concentration of SUS310S than that of SUS304. This results are consistent with the solid solubility of nitrogen shown in the phase diagram of Fe-N systems. XRD analysis indicated that the nitrided layer of SUS310S consists of both γ' and α'. The nitrogen concentration and expansion rate of γ' estimated by XRD analysis was higher than that of α'. Those results infer that the high expansion rate of γ' causes severe spalling susceptibility of the SUS310S heating tubes.

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In this paper, the stress intensity factor (SIF) solutions for subsurface elliptical cracks near the free surface in flat plates were numerically investigated based on finite element analyses. The cracks with aspect ratios a/l = 0, 0.1, 0.2, 0.3, 0.4 and 0.5, normalized ratios aid 0, 0.1, 0.2, 0.4, 0.6 and 0.8 and d/t= 0.1 were taken into account, where a is the crack half-depth, l is the crack length, d is the distance from subsurface crack to the nearest free surface and t is the wall thickness. Fourth-order polynomial stress distributions in the thickness direction were considered. It was concluded that the numerical SIF solutions presented in the paper are useful in engineering applications.

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Flaw evaluation methods defined in the Fitness-for-Service Codes of Japan Society of Mechanical Engineers are applicable limited to a single flaw. However, multiple stress corrosion cracks were observed in a weld joint in some components of nuclear power plants, such as recirculation system piping of boiling water reactors. For applying to the flaw evaluation like this case, stress intensity factor evaluation method for multiple circumferential flaws in a cylinder was examined in this study. Based on the solution of stress intensity factor for a single flaw, procedure to evaluate stress intensity factor for multiple circumferential flaws was proposed. The proposed method is applicable to arbitrary flaws (sizes and positions) subjected to bending moment.

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An overpack which is a disposal package for high-level radioactive waste has been required containment of radionuclides to prevent contact between groundwater and vitrified waste for 1,000 years. To encapsulate the verified waste in the overpack, welding is under consideration. The method for ensuring long-term integrity of the overpack should be considered on corrosion evaluation and structural integrity evaluation. The structural integrity evaluation to prevent fracture by load consists of strength evaluation and flaw evaluation. In this study, the stress intensity factors at the crack tip in welded part were calculated to investigate critical crack size using finite element analysis. External pressure and welding residual stress were considered in the analysis. It was shown that the effect of welding residual stress on stress intensity factor was relatively large compared with external pressure. The relationship between critical crack size and allowable residual stress were calculated using these results. It was concluded that when fracture toughness and welding residual stress were given, measurement flaw size using non-destructive testing could be estimated.

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The elastic-plastic FE analysis is needed to know a plastic behavior of the RPV inner surface caused by rapid cooling during PTS events. However, the J-integral is not path-independent for elastic-plastic material in the unloading process. Therefore, the combination of the Stress Intensity Factor (SIF) derived from a FE analysis based on a model consisting of elastic-plastic cladding and linear elastic low alloy steel with the subsequent plastic zone correction is examined, since the stress level of low alloy steel remains within elastic region during PTS events. Furthermore, the method for including the effect of residual stress into the SIF is investigated.

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Structural integrity assessment of aged pressure equipment is performed using several procedures based on reliability. Partial Safety Factor (PSF) method is one of the most useful reliability analysis procedures. Users can easily perform the reliability analysis using the PSF method instead of a detailed probability of failure analysis, i.e., the Monte Carlo method. In this study, the PSF method was applied to Fitness-For-Service assessment of pressure equipment with local metal loss. The researchers developed the partial safety factors for typical pressure equipment, and proposed the metal loss assessment procedure using the PSF method.

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蒸気発生器の伝熱管は,原子炉冷却系の耐圧バウンダリであり,地震時にも健全であることが必要である.伝熱管の地震時挙動については既往研究にて,水平方向において面外方向と面内方向は独立した振動特性を示すことが確認されている.従来は,この振動特性を解析で模擬するための実用的な手法として複数の伝熱管を集約した簡易モデルを用いていたが,本研究では伝熱管群を構成する全ての部材を詳細にモデル化することにより,各伝熱管に発生する応力分布をより精緻に評価できる手法を構築した.

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By the linear viscoelastic theory in the textbook of viscoelasticity, the viscoelastic parameters obtained by different viscoelastic tests can be interconversion. However, this interconversion is based on that theory, the interconversion of the experimental data have not seen yet. In this study, the viscoelastic tests were carried out with different environment and same test conditions. And also we carried out the viscoelastic tests with the same testing apparatus and using the same materials. The results showed the difference in the environment on the viscoelastic tests, the silicon oil environment more progressed the creep behavior than the air environment. This is because that the silicon oil's thermal conductivity is one fourth of the air, and the heat generated with the deformation could not escape from the surface of the materials. In addition, the static bending tests were carried out with different strain rate and stress rate at elevated temperature. The results of static bending tests were converted to the creep compliances, then the results were compared with master curve of short term creep tests and 1 month long term creep tests. The results shows the good agreement between the master curve and long term creep tests. However the creep compliances obtained by static bending tests showed the different creep behaviors.

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In this study, to determine the thermo-viscoelastic properties (shift factors and a master curve) of a borosilicate glass (IWAKI_<TE-32>), dynamic mechanical analysis (DMA) using a thermomechanical analyzer were carried out under various frequencies and temperatures. It is confirmed that the storage elastic moduli decreased with increasing temperature in 575℃ to 770℃ and decreasing frequency in 0.001 Hz to 0.1 Hz. However, the storage elastic moduli estimated by DMA was much smaller than reported glass Young's modulus of 61GPa. Therefore, the storage elastic moduli were corrected by measuring a machine compliance. Moreover, shift factors and a master curve of the glass were derived by applying time (frequency)-temperature superposition principle to datasets of the corrected storage elastic moduli.

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This paper presents evaluation of fiber/matrix bonding strength in heat resistance polymeric composites. Interfacial property is one of the important factors dominating whole composite mechanical performance. Micro droplet test is examined by a micro mechanical testing machine. The load value obtained by the test is employed as a boundary condition of the corresponding finite element model, in which cohesive element is inserted into fiber/matrix interface to simulate interfacial debonding. Also, continuum damage mechanics is applied to resin in the model because a resin damage is more or less accompanied with the interface debonding in expreiments. Combining the experimental and numerical reslts, the interface strength is identified for each specimen.

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In this research, impact reduction effect of acrylic foam film was clarified by using dynamic three-point bending testing machine. The specimens were an aluminum alloy (JIS A6063) beams with an acrylic foam films on surfaces of the beams. The acrylic foam film had thickness of 700 μm and density of 0.5 mg/mm^3 on a polyethylene terephthalate substrate film with a thickness of 38 μm. The aluminum alloy beam had thickness of 3, 6 and 10 mm. The input and output bars in the three-point bending testing machine were made of aluminum alloy (JIS A7075-T6). The bars were 2 m in length and 12 mm in diameter. The striker made of polycarbonate was 200 mm in length and 12 mm in diameter. Impact load was applied to the input bar by colliding the striker. Impact load and reaction load were calculated from strain histories of the input and output bars due to one-dimensional elasto-dynamic theory. Histories of the impact loads for the specimens with the acrylic foam film were lower than the one for the specimens without the acrylic foam film. The maximum impact loads for the specimens 10 mm in thickness with the acrylic foam film was 20% smaller than the one for the specimens without the film. The acrylic foam films were found to be effective to the impact load reduction for higher stiffness of a structure.

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In the present study, a novel CFRP (carbon fiber reinforced plastics) is proposed by using soft epoxy resin as a matrix. The elastic modulus of the soft epoxy resin strongly depends on the strain rate. Firstly, CFRPs were fabricated with the soft epoxy matrix and a standard carbon woven fabrics. The carbon woven fabrics of 5 layers were laminated to be quasi-isotropic. Then, static tensile and three point bending tests were conducted to evaluate the tensile and bending moduli of CFRPs. The experiment reveal CFRPs with soft epoxy matrix show high tensile modulus and low bending modulus which depends on the deflection velocity.

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This paper introduces "Tapping AE method" which is a new NDT method for CFRP. CFRP has a large number of advantages, although, internal damage easily occurs in it when impact load is applied. The typical NDT method to detect internal damages of CFRP are ultrasonic testing and tap testing. Although UT is reliable method for its high detectability, UT is a time and cost consuming method. On the other hand, tapping method is a quick and easy way to conduct, although, the detectability of the method is insufficient for main component materials. The aim of developing tapping AE method is realizing high-detectability tap testing. In Tapping AE method, the specimen is tapped by a hammer and secondary AE emitted from the damages are measured by AE sensor installed in the hammer during the hammer tapping. In order to evaluate feasibility of tapping AE method, we developed tapping AE system. The test was applied to a cross-ply CFRP laminate with and without internal damages. During the test, secondary AE signals were successfully observed.

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