Heinrich's law has been well known as the probabilistic law in which one seriously injured accident of the work place hazard can be statistically led from the certain number of disaster without injury. In this paper, the process of the labor hazard is modeled as the spatio-temporal evolutional problem from the view points of complex system. The cellular automata (CA) method is applied to solve this process as the metaphor model under the appropriate local rule. The effects of initial existence probability of the disaster without injury and kinds of local rules employed in the CA are discussed with much emphasis. Then, the probability of each level accident as the results of the pattern dynamics is assessed, being compared with the Heinrich's law and it is found that the initial probability of 55% suits this experienced law.

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Aggravation of air pollution containing suspended particle matter (SPM) discharged from various sources is one of serious environmental problems. The simulation of diffusion behavior of SPM is performed, using the multilevel simulation of combining random walk of particles and parallel finite element air flow analysis.

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This paper describes a development of the traffic simulator using multi-agent approach and its application to a real world problem. We newly implemented tram and pedestrian agents to the simulator. The goal is to develop a simulation system to be used for assessment of transportation policy such as introduction of LRT lines. Here each car, tram, or pedestrian is modeled as an intelligent agent, and traffic phenomena emerge from interactions among these agents. We applied our simulator to single intersection to evaluate its behavior quantitatively. The simulated results are consistent with the theoretical value. Then we applied the simulator to a city traffic problem for which citizens actually discuss the plan to extend tram route.

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For improving conservative property of CIVA-based CFD methods, we present a new conservative advection scheme using CIVA on unstructured mesh. The scheme is based on the governing equation in conservative form and finite volume discretization. In order to stabilize the scheme, we introduce a new scheme; derivative artificial viscosity (DAV). We confirm the effectiveness through some numerical benchmark simulations.

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We propose a 4th-order conservative scheme for transport equation on triangular unstructured grids based on the underlying concept of the CIP method. Two types of so-called "moments", defined as the volume integrated average (VIA) and the point value (PV) of physical field are used as the prognostic variables to be carried forward in time separately. VIA is updated by a flux formulation, and PVs are updated by a semi-Lagrangian scheme. A 2D cubic polynomial can be construction over a single triangular element. The 4^<th>-order accuracy of the numerical scheme is verified by numerical tests. The proposed method appears to be very robust to different unstructured grids.

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We show that the CIP scheme and the IDO scheme can resolve higher wavenumber than the sixth-order Finite Difference (FD) scheme, the fourth-order Compact Difference (CD) scheme, and the sixth-order Combined CD (CCD) scheme for the advection equation. The numerical viscosity in the upwind interpolation function of the CIP scheme consists of the combination of the fourth-order and the fifth-order derivative terms, and contributes to stabilize the solution including wavenumber near w=π. Not only for the advection term but also for the non-advection terms, the IDO scheme resolves higher wavenumber than the other schemes, and provides spectral-like solutions for the direct numerical simulation of the turbulence flow.

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This paper presents rational function based fully multi-dimensional advection schemes for structured and unstructured grids of a quadrilateral geometry. For the structured grid, a fully 2D rational interpolation function is constructed by combining two 1D sweeps based on the 1D rational function with 3 degrees of freedoms, and is convexity preserving. For the unstructured, the interpolation function is constructed according to the same procedure as in the structured grid after each control volume is mapped to a rectangle. Numerical tests of advection transport show that the constructed rational interpolation functions effectively eliminate the numerical oscillations and give well-regulated solutions.

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With the progress of human activities in space, the occasion to handle liquids under low-gravity conditions is now growing. The absence or diminution of gravity force makes it difficult to position and control the liquid in a desirable manner. For the establishment of the technology for the management of liquid propellant in space vehicles, a numerical method, called 'CIP-LSM' (CIP Level Set method and MARS), was developed to simulate three-dimensional free-surface flows under various gravity conditions, which has been applied to clarify the dynamic behavior of liquid propellant in the tanks of launch vehicles.

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In this paper, we introduce the multi-block method to the CIP/Multi-Moment Finite Volume Method (CIP/MM-FVM) to make the numerical model more flexible and more efficient in the presence of complex geometry. Because the stencil required for the reconstruction in the CIP/MM-FVM is compact, the halo region for the block boundary is of only one grid spacing. The accuracy and the conservatively of the original CIP/MM-FVM is maintained by imposing proper conditions at the common boundary of two different blocks. Numerical experiments have been carried out to verify the proposed method.

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Propulsion mechanism of water strider which resolves Denny's paradox has not yet been proposed until now. Here we present experimental and simulation studies on such phenomena. As a simulation model, we have developed a new method to treat the contact angle including surface tension which is the key issue in the movement of water strider. By comparing experiments and simulation, we found there are two distinct mechanisms for the movement. This could resolve Denny's paradox.

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Most of the existing numerical models for the simulation of Tsunami are based on the 2D shallow water equations. However, for many situations, it is necessary to use the 3D model in addition to the shallow water models to evaluate the damage in the coast region with a reliable accuracy. So, we propose the multi-scale warning system for Tsunami by connecting these models to cover the physical phenomena that have diverse scales in both time and space. In this paper, we present the formulation of the 2D shallow water wave model based on the CIP/Multi-Moment concept and the theory of characteristics. As the first step of this system, we apply CIP-CSL scheme to the rectangular structured grid and the triangle unstructured grid.

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In order to clarify the crack closure and reopening point of fatigue crack, crack-tip in 316FR steel is continuously observed during the high-temperature fatigue crack propagation tests, which is carried out under several stress ratio conditions, by means of a CCD-microscope and videorecording system. The crack opening ratio q_o which is obtained by the pattern matching of the pictures, is varied by the stress ratio. The relationship between the stress ratio and q_o can be estimated well by the equation which is already proposed by one of the authers after the crack propagation analysis of tested material.

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In order to clarify the effect of microscopic inhomogeneity on driving force of crack propagation (elastic J-integral), elastic finite element anarlysis (FEA) is carried out for a cracked body of which grain-shape and orientation, and crack shape are reproduced from a fatigue crack propagation test specimen of directionally solidified superalloy. Here, the load axis is set to be perpendicular to the solidification axis. The analysis reveals that J-integral is affected by two factors, elastic compliance nearby the crack tip and the angle between the crack tip and load axis. The former causes the submm order of fluctuation in J-integral, and the latter causes the sporadic drop of J-integral at the point where the crack direction is largely apart from the direction normal to the load axis.

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Precise prediction of the residual life of the components under long-term-service is strongly required from the demand of the maintenance-cost reduction on the thermal power plants. Quantitative prediction of crack growth under the displacement-controlled condition such as thermal fatigue is the key for these needs. In the previous paper, we have proposed a simplified prediction method of the J-integral of some specimens under the displacement-controlled condition, on the basis of the displacement-based approach instead of the reference stress approach. In this paper, creep-fatigue crack growth behavior for a semi-circular notched plate of CrMoV cast steel under displacement-controlled conditions is numerically and experimentally examined. The effect of stress-strain curve used for crack growth simulation on crack growth behavior is also discussed.

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The effect of overload on fatigue crack growth of an epoxy resin filled with crushed silica particles was investigated. The acceleration of crack growth during overloading was not caused by a single peak overload. However, the retardation of the crack growth after overloading was caused by a single peak overload. The retardation effect of the crack growth after continuous cyclic overloads was larger than the case of a single peak overload.

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Extreme value analysis has been applied to clarify the statistical nature of ductile fracture surfaces associated with fracture behavior of tensile specimens for JIS SS400 steeel. Both the notched tensile specimens with different notch acuity and the unnotched specimens were employed to obtain a wide range of stress triaxiality.The ductile fracture surfaces were composed of variously sized dimples. The extreme value probability plots of the maximum dimple sizes in a given unit area were performed to correlate the dominant feature of the ductile fracture surfaces with the fracture strains. The location parameter that defines the maximum dimple size distribution showed a clear dependence on the fracture strains of tensile specimens. The extreme value analysis of the ductile fracture surface should be recommended as a powerful tool for providing a quantitative information regarding the fracture behavior of the mechanical components.

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It is necessary to reduce maintenance cost and extend the life of gas turbine blade which is one of the important parts of gas turbine. Various life extension methods (Heat treatment, HIP(Hot Isostatic Pressing)) which recover creep and fatigue damage of gas turbine blade due to long term service are proposed. But there is no quantitative report about the effect of these methods on life extension of gas turbine blade. In this report, we described mechanical properties and microstructure of second stage blades for 1100℃ class gas turbine, which refurbished by heat treatment and HIP after service. Following are the conclusion of this investigation, microstructure degradation (coarsening of γ' phase), creep damage, thermal fatigue damage and ductility loss due to service exposure can be recovered by the previous refurbishment as same as virgin material. Difference between effect of HIP and that of heat treatment are almost negligible. It is possible to extend the life of second stage blades for double by using the previous refurbishment.

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Much Hydrogen penetrates from a container wall surface when a petroleum-refining reactor operates under high temperature and pressurized hydrogen environmental condition. Major part of the hydrogen remains in the wall for a long time during cooling process when the reactor is out of operation, which results in the inducement of peculiar delayed fracture. In this paper, the proposed analytical method on hydrogen diffusion and concentration around a crack tip was applied to this phenomenon mentioned behavior was clarified.

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The objective of this research was to determine the effects of shot peening intensity on fatigue crack growth in 7075-T735 single-edged notch bend specimens (SENB) specimens. The SENB specimens were tested in the as-received and shot peened (with four Almen scales (4,8,12,16)) conditions, with crack perpendicular to the rolling direction, i.e. in the L-T direction. The striations in the SEM micrographs were used to calculate the crack growth rate, da/dN. The 3-D K along the curved and tunneled crack front in a loaded SENB specimen with residual stress measured by using an X-ray diffraction stress analyzer was obtained through the J integral computed from a 3-D finite element analysis. The crack growth rate at the initial phase of crack growth in the shot-peened specimens is significantly higher than that of the as-received specimen.

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Cavitation impacts normally cause severe damage in hydraulic machinery. However, cavitation impacts can be utilized for surface enhancement as same way as shot peening SP. Peeing method using cavitation impacts is called as "cavitation shotless peening CSP," as shots are not required. Fatigue strength of carburized chrome-molybdenum steel treated by CSP was better than that of SP, even though the residual stress of CSP was lower than that of SP measured by a conventional X-ray diffraction method. CSP can also improves the life time of forging die, even though introduced compressive residual stress was not so large. Recently, 2D method using two dimensional position sensitive proportional counter PSPC has been developed to measure micro strain. In case of 2D method, the residual stress within thin layer near surface can be measured by controlling an incident angle of X-ray. The distribution of residual stress of sub-surface peened by CSP changing with depth was measured by 2D method without removing the surface. It was concluded that the compressive residual stress on the surface of CSP was larger than that of SP.

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Effect of loading frequency on fatigue behavior of structural plywood under shear load through the thickness was experimentally investigated. Pulsating load with loading frequency of 0.5 or 5Hz was applied along the length of specimens. Applied peak stress was determined as 0.5, 0.7, and 0.9 stress levels. Hysteresis loop for each loading cycle was determined by measuring the load and the shear strain at the center of the specimen surface throughout the fatigue tests. The area enclosed by a hysteresis loop was defined as the energy loss per cycle. Fatigue life obtained in each stress level was longer at higher loading frequency. Energy loss per cycle was observed to be smaller at higher loading frequency, causing less damage to plywood specimen. Cumulative energy loss, which is the sum of energy loss per cycle throughout fatigue test, was almost the same value between the two loading frequencies in each stress level. Cumulative energy loss could be, therefore, a fatigue indicator independently of loading frequency that substitute for fatigue life.

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Mg_2Si-dispersed magnesium alloys were produced by solid-state synthesis using AZ31 and SiO_2 powders as starting materials in which two different powder sizes in AZ31 were used. Then extrusion was applied to produce bars of 24mm diameter. Rotating bending fatigue tests were performed using smooth specimens of the extruded materials in laboratory air at ambient temperature. It was found that Mg_2Si-dispersed Mg alloys showed lower fatigue strength than the extruded AZ31 alloy and the fatigue strength of the material using coarse powder decreased significantly. Fatigue cracks always initiated from large particles immediately after cyclic loading was applied and subsequent small crack growth was faster than the extruded AZ31 alloy. It was concluded, therefore, that the decrease of the fatigue strength of Mg_2Si-dispersed Mg alloys was attributed to the premature crack initiation from particles and faster small crack growth and the observed powder size dependence of fatigue strength was due to difference in the size of the particle from which the crack initiated.

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To evaluate the effects of grain size on high cycle fatigue property, rotate-bending fatigue tests were conducted on AZ31 extruded magnesium alloy of two grain size, 29 and 47μm. In this study ,the different grain sizes have little effect on the fatigue strength at 10^7 cycles. It is because the fatigue crack initiation sites of two kinds of materials were all comparatively big inclusions. However, the fatigue life of the large grain size specimens is longer than that of the small grain size specimens. It was thought that the property of small fatigue crack propagation is different.

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Fully reversed axial fatigue tests were conducted on a cast aluminium alloy, AC4CH, at three different temperatures of room temperature (R.T.), 150℃ (423K) and 250℃ (523K). The fatigue strength decreased as test temperature increased. The fatigue strength characterized in terms of fatigue ratio, σ/σ_B, was similar at all temperatures, but slightly lower at 250℃ in low stress region. Cracks invariably initiated from a casting porosity at R.T., while crack initiation due to slip deformation became dominant at elevated temperatures. At 250℃, the number of cracks initiated due to slip deformation was the largest and the coalescence of the main crack and other cracks was observed most frequently in low stress region, being responsible for the lowest fatigue strength characterized in terms of fatigue ratio at this temperature.

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Fatigue crack growth tests were carried out using CT specimens of ultra fine-grained P/M (Powder Metallurgy) aluminum alloy of which grain size was from 200 to 500nm. The effect of pre-plastic working on fatigue crack growth behavior was investigated under constant amplitude. Fatigue fracture toughness K_<fc> became the highest for material of 30% forging ratio. It was found that crack tip branched and deflected due to redistribution of inclusion by forging.

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Mechanism of fatigue crack path in anisotropic pure aluminum sheets was investigated using as received and annealed CCT-specimens. From fatigue tests, it were found that the crack grew to the rolling direction about 30 degrees towards loading direction in as received specimen, but not for specimen annealed in 290℃, 30 minutes. According to the fracture surface examination and pole figure determination using X-ray diffraction, it was confirmed that slip plane (111) mainly existed in the rolling direction and the fracture surface of the crack that grew on the rolling direction. Fatigue crack that grows to the rolling direction as mixed mode I-II crack is caused by the strong texture of slip plane (111) in the rolling direction that makes simple slip system and the mode II crack easily occurs so that the crack propagates to the rolling direction as continuous crack initiation process.

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The mechanism of fatigue crack propagation in pure aluminum was investigated. In the present study, push-pull fatigue test of plate type specimens in which slit was cut in the center section of the test section was performed. The slit direction cut in specimen was perpendicular to axial direction or 45 degree inclined direction from center axis of the specimen. The crack propagated by mode I or by mixed mode that combined with mode I and shear mode, depending on the testing conditions. However the crack propagation rate da/dN was evaluated with modified effective stress intensity factor range independent of the crack propagation mode. In the pure aluminum case, the shear stress strongly affected crack propagation rate. This is considered to be related to the crystal structure.

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Using an ultrafine grained copper processed by ECAP, rotating bending fatigue tests have been carried out. Significant differences in morphological feature in post-fatigued surfaces between high and low cyclic stress amplitudes were observed. To clarify the formation process of surface damage, morphological changes in surface damage caused by cyclic stresses were monitored successively by an optical microscope. Putting those OM observations and SEM observations of post-fatigued surfaces together, the formation processes of surface damage were discussed.

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From the saturated stress-strain hysteresis loops in low-cycle fatigue tests of steels, it is found that complementary energy is varied in proportion to plastic strain ranges. In simulating the hysteresis loop by a paralleled spring-slider combined model, the complementary energy means the elastic energy accumulated in the spring and the spring-constant needs to be in inverse proportion to the plastic strain range. Based on such characteristics of the complementary energy, the behavior of a cell-structure formed in low-cycle fatigue is discussed.

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Electron backscattering diffraction (EBSD) method and atomic force microscopy (AFM) were utilized to investigate the active slip systems and fatigue crack initiation behavior in stainless steel, SUS316NG, under torsion. The analysis of active slip systems based on Schmid factor shows that most grains possess the slip plane with the largest Schmid factor value as their primary slip plane. Fatigue cracks were divided into 4 types: GB (Grain Boundary), TB (Twin Boundary), SB (Slip Band), TC (Transcrystalline). The results of crack density distribution in comparison with the earlier research in tensional fatigue tests show that under low loading level TC cracks dominate the initiation stage regardless of the loading mode. The profile at the cross section of SB crack was measured by AFM. The observed tilt angle of slip plane agrees very with its theoretic value.

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Fully reversed total-axial-strain-controlled low cycle fatigue (LCF) tests have been conducted in air at room temperature on 18Cr-8Ni austenitic stainless steel. Three types of hardness measurements, namely nano-indentation, micro-indentation and conventional Vickers hardness tests, with the indentation size ranging from several tens of nm to several tens of μm, were performed for both virgin and fatigued specimens to evaluate the mechanical behaviour at different scales of the cyclically deformed steel during LCF. OM and TEM observation showed that the microstructural parameters are the dislocation cell size, d_<cell>, slip spacing, w_<slip>, and austenitic grain size, d_γ. Referring 10 d_<cell> and 10w_<slip>. Vickers hardness, HV, corresponding to macro strength was expressed as HV=Hv^*_<base> +Hv^*_<sol> +Hv^*_<cell> +Hv^*_<slip>. Hv^*_<base> is the base hardness, Hv^*_<sol> is the solid solution strengthening hardness, and Hv^*_<cell> and Hv^*_<slip> are the fine grain strengthening hardness due to the dislocation cell and slip band.

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As for the fatigue strength characteristic, a crack propagating curve (da/dN-&lrtri;K) is mainly used. The curve, which is classified into 3 steps, shows material characteristics in each area. We aimed at the last fracture surface and this research analyzed fracture surface. That is, as for the material which underwent surface modification with high toughness and high strength steel, both the surface crack spread and the inner crack spread exist. Therefore, We analyzed fracture surface where there was fracture in the repeat of the low stress power using the high strength high toughness austempered spheroidal graphite cast iron with the minute flaw for which it is easy to occur inside. We researched for the minute yielding area using the fractal dimension method in the analysis, calculating a destruction toughness value (K_<Ic>) in seeking that case and we got a valid result. The state of which a cleavage surface is formed around the minute flaw, it propagates inside and spreads next from the crosswise direction to the surface were shown. As these, as for the fracture mechanism of the 2-bending curve, that the surface crack didn't become dominant became clear. We think that one with the crack surface, which spreads inside, is caused by the surface hardness gradient.

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SKD steels are important materials for industry due to excellent characteristics such as high heat-resistant ability, excellent machinability, high wearable ability and high impact endurance. Ion Nitriding is widely used in industrial area, as a reliable, repeatable, economical and environmentally acceptable process. In this study, fatigue test had been performed to investigate the effect of Ion Nitriding on SKD steel. Six kinds of Ion Nitriding methods were used in this study. The fracture surface, the Ion Nitriding layer and the hardness distribution were also described in this paper. The result of this test showed the optimal Ion Nitriding method on improving the fatigue properties of this kind of material. Hardness of the specimens increased remarkably after Ion Nitriding process.

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The comparison and relations between fatigue strength with hardness were investigated using eight types of specimens; un-nitrided and ion-nitrided specimens. The fatigue properties of the ultra-low carbon steel sheets (ULCS) have been assessed by evaluating fatigue strength and hardness profile using fully reverse plain bending fatigue testing machine at constant speed of 2000 rpm with the capacity of 49Nm, microhardness tester, an optical microscope and scanning electron microscope (SEM). It was found that ion nitriding improves the fatigue strength by increasing the nitrided layer depth, however the compound layer was found not to have a dominant effect on the fatigue strength. The comparison of test result between un-nitrided and ion-nitrided specimens has shown that the fatigue strength increases up to 37% which could be reached by ion-nitriding process.

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Three point bending fatigue tests were carried out using S45C steel with CrN film. The film was coated onto S45C steel by arc ion plating method. In order to investigate the effect of coating condition on the fatigue behavior, the films were coated under two different conditions. As a result, the fatigue strength was increased coated under low arc current and bias voltage, while the fatigue strength of high arc current and bias voltage. The change of the fatigue behavior was mainly caused by the difference of crack initiation.

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In order to investigate the effect of coating condition on the fatigue properties of high strength steel, the four point bending fatigue tests were carried out for martensitic stainless steel with TiN film coated by arc ion plating (AIP) method. TiN film having 2μm thick was deposited onto the substrate surface under four kind of the bias voltage; V_B=0, -60, -160 and -260V. For V_B=0, -160V and -260V, the fatigue limit increased. The highest fatigue limit of σ_<max>=900MPa was obtained for V_B=-160V. For V_B=-60V and -260V with film delamination, the fatigue limit was decreased by coating. It appears that the fatigue properties of the coatings strongly depend on the crack initiation behavior. The fatigue crack initiated from subsurface in the substrate independent of bias voltages and the crack initiation life depended on the surface roughness, adhesive strength, residual stress, elastic modulus, and hardness of the films.

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This paper describes the estimate method of the effect of plating thickness on the fatigue strength of galvanized steel. We carried out fatigue tests of High-Tensile Steel HT80 that we made hot-dip or electricity galvanizing on. As a result, the fatigue strength did not depend on form of the galvanizing layer and confirmed that the fatigue strength was in inverse proportion to the plating thickness. And these fatigue strength understood that they almost agreed with estimated fatigue strength by fracture mechanics analysis using "intrinsic crack model" by grinding plating thickness with an initial defect. Based on this result, we suggested technique to evaluate fatigue strength of galvanized steel from hardness of the base metal.

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The surface strain of thermal sprayed coating and substrate were measured with ESPI method and the delamination behavior of sprayed coating investigated by comparing the surface strain of both materials. Then it was examined that the generation of delamination was defined. As the results, both surface strain was corresponding until some stresses when thermal sprayed coating and substrate were added static load. But surface strain of thermal sprayed coating was decreased while some cracks and delaminations occurred on coating or coating/substrate, and the value of strain has become considerably small than surface strain of substrate. Therefore, it is thought the delamination of coating can be defined according to critical strain due to the surface strain of both materials. Moreover, it may be effective as the evaluation method that the quality of the coating was evaluated by using critical strain of delamination obtained by ESPI method.

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In the present study, the effects of carbon content on the tortional fatigue properties have been investigated using four kinds of structural carbon steels, S15C, S25C, S35C and S45C with different tensile pre-strain ratios, in the view-point of fatigue strength, crack initiation and propagation and the non-propagating crack behaviors. According to the experimental results and observation of crack propagation behaviors, the main results obtained in this study are as follows: (1) The increasing of carbon content improves the fatigue strength of test materials with the same tensile pre-strain ratio. (2) Carbon content difference does not affect the initiation point, crack branch point and branch direction of the torsional fatigue cracks. (3) The length of the non-propagating cracks decreases with the increasing of carbon content for materials with the same tensile pre-strain ratio.

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This study examined fatigue properties of tempered steel that used the super rapid induction heating technology. The experiment used the hollow specimen to ignore the residual stress generated by the induction hardening and to extract the property only of the tempering microstructure. As a result, the following conclusions could be summarized. (1) The precipitates in the super rapid induction tempered steel were finely dispersed than the furnace tempered steel. (2) The fatigue life showed almost the same tendency without relation to the hardness and tempering condition. (3) As for the fatigue limit in 450HV, the improvement effect by the super rapid induction tempering was recognized.

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In the extremely low cycle fatigue, a transition of the fracture mode occurs from the surface to internal fracture with an increase in the plastic strain range. Such a transition is caused by an increase in the paerlite cracking inside the material. The pearlite cracking is greatly dependent on the own direction of lamellael in a pearlite grain. Work Hardening and paearlite grain turning under cyclic plastic strain affects an increase in the paearlite cracking.

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In order to investigate the relation between one stress cycle and temperature change under stress cycle with mean stress, temperature change have been measured by using computerized temperature measurement system. Under erastic stress range, the temperature changes are agreed well with the thermo-elastic value. But under plastic stress range, the temperature changes are lager than the calculated value. The temperature change under tensile mean stress is smaller than the value under compressive mean stress. This results seems to be come up the tensile stress yielding.

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Using a fatigue testing method by which fatigue cracks can be initiated and propagated in a film adhered to cover a circular through-hole in a base plate subjected to cyclic loads, annealed rolled pure copper films of 100μm thickness were fatigued. In order to discuss about the correlation between fatigue crack propagation and the change of electric properties, the electric resistance of the copper film was measured by four-point probe method. As a result, the electronic resistance was changed remarkably at the slip initiation and the crack initiation.

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Using model specimens where pure copper films were bonded to the surface of S45C steel base plates with epoxy resin, the initial tensile residual stress on the copper film was changed into a compressive residual stress by peening with fine ceramics particles accelerated by waterjet. In the fatigue testing results, the specimen with a thicker bonding layer had a larger fatigue life than that with a thinner one, due to the larger crack propagation life through the bonding layer caused after the fracture of the film and the base plate. In addition, the relationship between the fatigue crack propagation rate, da/dN, and the crack opening displacement range at 100μm behind the crack tip, &lrtri;φ_<100>, on the epoxybonded film was almost the same as that for the steel base plate, irrespective of the bonding layer thickness.

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Recently, because the micro-machine is noticed and electronic equipments are made much lighter and smaller, the demand for micro materials is increasing. However the mechanical properties data of the micro materials obviously run short and the evaluation method of micro materials is different according to the researcher. Therefore, the establishment of the test method for the micro materials is very necessary. In this study, fatigue tests were carried out using SUS304 thin sheets with thicknesses of 20μm. The specimens were manufactured using electrical discharge machining (EDM). Except for EDM specimens, the specimens of whom the EDM surface was polished by alumina abrasives were prepared. As the results, it was seen that the fatigue lives of polishing specimens were longer than those of EDM specimens. The fatigue crack origins of polishing specimens were almost inclusion.

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In this report, butt welding with aluminum sheets of 0.3mm in thickness has been performed at welding speed of 1500〜6000mm/min by inverter controlled TIG welder. Aluminum sheets have been clamped between copper plates to restrain weld heat input what causes deformation for preceding area. Weld bead at high welding speed has been examined for mechanical properties. In particular, static deformed behavior of cross section of weld bead is photographed through polarization microscope. Consequently, as welding speed becomes high, deformation of weld bead has been restrained, and fatigue strength has progressed gradually until welding speed of 6000mm/min. This report has proposed that deformed behavior of weld bead affected fatigue strength.

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Micro-crack growth behaviors in ratcheting fatigue tests were investigasted to discuss the fatigue life reduction mechanism in ratcheting conditions. Ratcheting fatigue tests for 316FR stainless steel were conducted at 550C in order to discuss the design criteria for the commercialized fast reactor system. Fatigue lives decrease with increasing the accumulated strain, but the life reduction was negligible when the accumulated strain was less than 2.2%. Micro-crack growth behavior can be devided into initiation and growth stage. The crack initiation length was approximately 0.2mm. The initiation life was almost negligible when the fatigue life decreased by ratcheting. The micro-crack initiation life shortening was considered as the mechanism of fatigue life reduction in ratcheting conditions.

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In the structures or the components used at the high temperature, the ratchet deformation and the creep fatigue by the cyclic thermal stress are important breakage style. The influence of the ratchet deformation on fatigue strength at the high temperature is not necessarily clear, therefore it is demanded to clarify the tolerance. In this study, a new fatigue testing method of attention to two parameters like the accumulative strain and ratchet expired cycle was designed to understand the influence of the ratchet transformation on fatigue life under the fast reactor component condition, and the influence that the ratchet deformation exerted on the decrease in the fatigue life was examined.

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It is reported that fretting fatigue strength in hydrogen gas environment is lower than that in air. To clarify the mechanism of environtmental effect of hydrogen gas on fretting fatigue strength, fretting wear test machine was newly designed and fretting wear tests were conducted. The test machine is suitable for the precise measurement of relative slip amount and frictional force precisely. The materials were austenitic stainless steels SUS 304 and SUS 316L. The materials were solution heat treated. Tangential force coefficient in hydrogen environment increased compared with that in air. The high tangential force was considered to be a cause of low fretting fatigue strength in hydrogen gas environment. The absorption of hydrogen occurred during fretting wear test in hydrogen gas environment was detected by TDS. Absorption of hydrogen is also considered to be another cause of low fretting fatigue strength in hydrogen gas environment.

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