In a spray process, it is confirmed that a temperature of generation of residual stresses has to be clarified for mechanism in generation of residual stresses. But a mechanism of the temperature is largely-unexplored. Therefore, it's hard to say that it is clear up how important stresses of first stage are generated in a spray process. So in this report an estimation approach of residual stresses is proposed through the viewpoint of energy consumption. By measurements of a surface temperature, a base temperature and residual stresses for 1 sample, a parameter for presuming a temperature of generation of residual stresses is clear up. And residual stresses of other samples are presumed reasonably with the finite element analysis of thermal stress and the parameter. Accordingly, it is clear up that the proposed estimation approach is reasonable. Based on the estimation approach, the control approach of residual stresses is established. In this report a result of control of residual stresses with the control approach is shown. In addition, flowchart for control of residual stresses in product is presented. Accordingly, the residual stress can be controlled reasonably. The control approach of residual stresses is conductive to an advantage that give to user. And the control approach shows that it is important to control of the optimal residual stresses in use environment.

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The elasticity solutions of plates have been researched and used widely. The elasticity solutions of plane are applicable to structures only under the premise that an object is very thin. However, the limitation of the thickness has not been made clearly. Then, it is necessary to clarify it in order to use two-dimensional elasticity solutions properly. In this study, we analyzed three flat plate models containing a round hole of the same curvature radius by the finite element method, and compared the three-dimensional elasticity solutions with the two-dimensional elasticity solutions. Moreover the application limit of two-dimensional elasticity solutions was given.

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Composite materials are made of vapor-grown carbon fibers (VGCF) with aluminum based matrices. Two aluminum based matrices such as pure aluminum matrix and matrix added Al-12 Si to pure aluminum are chosen for the composite materials. The thermal conductivities of the composite materials were measured by the method of laser flash, and mechanical properties such as tensile strength and total elongation are measured by pure tensile tests. The test results show that the matrix added-Al-12 Si to the pure aluminum is benefit to increase the thermal conductivity of the composite materials of VGCF. The thermal conductivity of the composite material with the uniform alignment of VGCF is higher than that with the random alignment of the VGCF. However, the tensile strength of the composite of VGCF decreases in both case of the random alignment and the uniform alignment.

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Polypropylene (PP) /vapor grown carbon nanofiber (VGCF) composite films with highly orientated VGCF of 10-30 vol% were developed by drawing and subsequent extruding for functional micro device applications. Furthermore, the anisotropy of the mechanical, electrical and thermal properties were investigated. Good performance such as low electric resistivity, high storage modulus, high Young's modulus and high tensile strength was achieved in a drawing direction of the PP/VGCF composites. In the drawing direction, significant VGCF content dependences of these properties also appeared. On the other hand, these properties in a direction inclined at 45° and 90° to drawing direction were the nearly same.

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Glass Fiber Reinforced Plastics (GFRP) have been applied to products such as building components and various structural materials in industrial plants due to their excellent lightness and corrosion resistance, as well as weather resistance since the 1980's. Use of GFRP for large-scaled components and/or components with repetitive load has increasingly widespread in recent years, and both tensile and compressive properties have thus become important. Reinforcing laminate for GFRP has been mainly woven fabric such as glass woven roving due to its easy handling. However, its fiber winding and gap occurrence have been problems to be solved. In the recent years, new fiber fabrics for reinforcement have come on the market owing to rapid development of weaving machine, and one of the new fabrics is the stitched fabric. This glass fiber stitched fabric has been increasingly developed in Europe and all over the world for over ten years, and in Japan, has extended its application for ship for about ten years. This study investigates and examines GFRP reinforced with unidirectional glass fiber stitched fabric, in respects of the effect of fiber laminated constitution, fiber content and fiber diameter on tensile and compressive properties. Additionally, this study also examines relevance between weaving patter of fiber and strength property by comparing 0 degree/ 90 degree stitched fabric with GFRP with general woven roving.

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Due to low impact strength of C/C composites, it is important to evaluate impact damage properties and impact strength. In this study, the relationship between the impact load and displacement on a drop weight impact test at a low impact speed is used to evaluate the estimating method for dynamic mode II and mixed-mode fracture toughness of C/C composites. The measured impact load is decomposed in approximation components and detail components, and is reduced higher mode of vibration by multiple resolution analysis in wavelet transform. As a basis developing experimental identification techniques for boundary conditions, a technique for end notched flexure (ENF) and mixed-mode flexure (MMF) specimen that a beam of C/C composites is proposed. The proposed technique enables one to determine, using data of load variations and displacement variations, the boundary conditions in terms of spring constants of elastic support, damping coefficients, impact velocity and equivalent masses. The results are as follows : (1) The Daubechies' wavelet is useful for smoothing the impact load signals by multiple resolution analysis in wavelet transform. (2) This boundary condition identification method by the numerical analysis of a load variation and a displacement variation is effective, and it can use for calculating the dynamic fracture toughness value of C/C composites.

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SCC life estimation is very important to maintain the safety of nuclear power plants. One of the main research tasks in SCC life estimation is the evaluation of welding residual stress, which is the dominant stress causing SCC of nuclear power plants. Although some analytical research works have been conducted to clarify the welding residual stress, most of them are 2-dimensional analysis. In this paper, the authors report the residual stress of girth weld pipe obtained by axi-symmetrical and 3-dimensional numerical analyses, and these analytical results are compared with experimental residual stress measured by neutron diffraction method. It is concluded that the 3 dimensional analysis shows good correlation with measured results. And, if the temperature history is well simulated, the difference of residual stress between axi-symmetric and 3 dimensional analyses is relatively small so that axi-symmetric analysis can be used for preliminary residual stress analysis.

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This study was conducted to investigate the effect of DLC (diamond-like carbon) coating and a hybrid surface modification composed of plasma carburizing and DLC coating on the fatigue properties of Ti-6Al-4V alloy. In the hybrid surface modification, plasma carburizing at the first stage was conducted to generate a hardened layer for suppressing plastic deformation which can occur under the DLC layer. The results of tensile test showed that the static strengths of both the DLC-coated material and the hybrid surface-modified material were maintained because growth of microstructure in the substrate during the plasma carburizing and DLC coating was unremarkable. However, elongation of the hybrid surface-modified material was slightly decreased by cracking of the hardened layer. In the DLC-coated material, the DLC layer possessed a high adhesion so that it effectively suppressed fatigue crack initiation from the surface and the fatigue strength was improved by 10%. On the other hand, the adhesion of the DLC layer in the hybrid surface-modified material was lower than half of the adhesion in the DLC-coated material. Therefore, although the fatigue strength was improved by the hybrid surface modification, it was lower than the case of the DLC-coated material.

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In order to study the notch effect on rotating bending fatigue properties for SUS403 stainless steel, the rotating bending fatigue tests were carried out at room temperature, 300°C and 600°C with a frequency of 1200 cycles/min. The temperature dependence of fatigue limit and the estimation method of fatigue notch factor were investigated. The relationships between the fatigue limit σ_W of smooth specimen and the tensile strength σ_B and also σ_W and the Vickers hardness HV were obtained as σ_W=0.58σ_B=1.63 HV at every temperature. Furthermore the relationship between the parameter (β-1) √σ₀/σ_B and Kt-1 was proposed to estimate the fatigue notch factor, where σ0 is the tensile strength at room temperature, β is the fatigue notch factor at a certain temperature and Kt is the stress concentration factor. Then fatigue notch sensitivity factor η was obtained as η=0.056√σ_B/Kt. Using these results, the estimated fatigue limit was satisfactory and the predicted accuracy was ±10%.

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A technical method for retarding crack growth from pre-cracks by drilling holes in the vicinity of the crack tips was investigated. A series of fatigue crack growth tests were performed using double edge cracked specimen. In some specimens, holes were drilled in the vicinity of tips of precracks. Also, calking pins were inserted into holes in some cases. The crack growth lives of drilled specimens were longer than those of specimens without holes. The longest fatigue life was observed in a case of specimen with the pins. Drilling holes and calking pins could change the growth direction of cracks, and then the coalescence of cracks, which grew from both edges, could be prevented. Also, it was considered that the compressive residual stress, which occurred by calking pins, was more effective to retard the crack growth than the reducing stress concentration around initial crack tips, which occurred by drilling holes. Therefore, it is concluded that calking pins into holes, which drilled in the vicinity of crack tips, is the effective method for retarding crack growth and for preventing coalescences of cracks.

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Considered in this paper is a functionally graded piezoelectric material (FGPM) strip containing an embedded crack or an edge crack perpendicular to its boundaries. The problem is solved for an FGPM strip that is suddenly heated or cooled from the bottom surface. The top surface is maintained at the initial temperature. The crack faces are supposed to be completely insulated. Material properties are assumed to be exponentially dependent on the distance from the bottom surface. First, the transient temperature and thermal stress distributions in an uncracked strip are calculated by using the Laplace transform. Then, the thermal stress is used as the crack surface traction with opposite sign to formulate the mixed boundary value problem. By using the Fourier transform, the electromechanical problem is reduced to a singular integral equation which is solved numerically. The numerical results for the thermal stress intensity factors are computed as a function of the normalized time for various values of the nonhomogeneous and geometric parameters. The temperature and thermal stress distributions for the uncracked problem and the results for the crack contact problem are also included.

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In this paper, an analysis of one-dimensional wave propagation is carried out in which combined dynamic axial force and torsional moment are loaded on a thin-walled tube by using the incompressible elastic-plastic-viscoplastic constitutive equation. In this analysis, theoretical equations are derived for propagation speeds of elastic-plastic-viscoplastic stress waves. Moreover, the derived theoretical equations of propagation speeds are shown to be strain, strain rate, stress and stress rate dependent, and to include those of strain rate independent theory. Last, calculated examples are shown.

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There is much interest in the affects of osteoarthritis on load distribution in the knee and the development of suitable therapies. The fibula excision method is relatively simple method. However, few studies have examined the dynamic state of the knee and the adaptative condition after the procedure. In this paper, we examined the effects the of the fibula excision method on the meniscus, using the photoelastic 3-dimensional stress freezing method and a pressure gauge. Our results suggest that the fibula excision method is effective in minor osteoarthritis cases.

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Building a cross-industry database of pipe failure is an effective method to improve the evaluation accuracy of pipe failure rate. Although pipes have many common failure mechanisms, they are used in many different environments in each industry. Thus, to enable practical use of a cross-industry database, it is desirable to develop a method for evaluating pipe failure rate that is capable of modeling the variability between different industries. The hierarchical Bayes model is one method that can model the variability between different data sources. In this paper, a method for evaluating the pipe failure rate for one industry is developed based on the hierarchical Bayes model. Even when the database contains small number of failure records, this proposed method is always capable of utilizing those records to evaluate the failure rate for a specific industry. Using the proposed method in conjunction with a cross-industry pipe-failure database, the pipe-failure rate was evaluated to a greater accuracy than that obtained using the conventional Bayes method.

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Head injury caused by the traffic crash accident is recognized as a serious problem for the establishment of the safety society. Many studies have been done to elucidate the injury generation mechanism of the brain by using the finite element (FE) analyses. In this study, a multi-scale finite element code is newly developed to assess the head injury by employing the stress and strain based criterion. The nonlinear viscoelastic constitutive equation is employed both for the macroscopic and the microscopic scales. Macroscopic head model consists of the skull, cerebral spinal fluid (CSF), facial bone and brain tissue. Microscopic model consists of the blood vessels, blood and brain tissue. When the human head is loaded by the translational acceleration in the traffic accident, the human brain is damaged at the crash side and the counter side, such as the coup and the contre-coup brain injuries. At the macro scale, the compressive hydraulic pressure was concentrated on the coup side, and the expansive hydraulic pressure on the contre-coup side. By employing the boundary velocity, which is derived from the macro FE analysis, the micro FE analysis is carried out. It shows that a very high equivalent stress, obtained by high tensile and shear stresses, occurred in the blood vessel. It was suggested that this multi-scale FE analysis could predict the blood vessel injury by employing the critical injury stress-strain criterion at the macro and micro scale.

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The objective of this study is to establish a prediction method of the head crash injury at the nerve cell level by employing the stress and strain based criterion. We focus on the diffuse axonal injury (DAI) as the nerve cell injury. We employ the multi-scale finite element (FE) code to analyze the stress and strain responses by using the macroscopic brain model and microscopic cell model. A three-dimensional microscopic nerve cell FE model is built by employing measured results of PC-12 cultured nerve cells. When human head is crashed through the translational acceleration in traffic accident, the human brain is damaged at the crash side and the counter side, such as the coup and the contre-coup brain injuries. At the microscopic scale, numerical results show clearly that a very high equivalent stress, which means high tensile and shear stresses, occurred at the part of nerve axon. It was confirmed that our multi-scale FE analysis could predict the DAI by employing the critical injury stress and strain criteria at both macro and micro scales.

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A computational prediction scheme of preferred orientations on various substrates by first principles calculation was proposed to design epitaxial piezoelectric thin film fabricated by sputtering, chemical vapor deposition and molecular beam epitaxy processes. At first, we computed epitaxial strain in piezoelectric thin film caused by lattice mismatch with substrate. When epitaxial strain is applied to crystal unit cell, total energy was evaluated by employing pseudo-potential method in density functional theory. Then, preferred orientations were predicted in view of stability of crystal cluster with various conformations on substrate. From application to BaTiO₃ thin films fabricated on SrTiO₃ (110), SrTiO₃ (001), MgO (100) and LaTiO₃ (001), calculations indicated that total energy increment of cluster was available to evaluate the possibility of crystal growth. Calculational results of preferred orientations had good correlation with experimental.

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This paper describes pilot study relevant to the application of Risk Informed In-Service Inspection (RI-ISI) in a BWR plant. This study conducted for typical BWR5 plant of Tokyo Electric Power Company, and partial application of RI-ISI limited in class 1 piping was carried out. A series of studies related to RI-ISI-segments division process, assessment of degradation possibility in segments, failure probability assessment of segments, risk assessment, risk significant assessment and ISI planning-was performed. The inspected portion and its frequency at the time of applying RI-ISI was decided so as to not exceed core damage probability (CDF) at the time of applying the conventional inspection method. As a result, volumetric examination in ISI will not required in 70% of segments (47 segments in 68 segments), and it suggests that the application of RI-ISI is much effective for reduction of radioactive exposure of inspectors without increase of risk by introducing RI-ISI.

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