In electronic packages such as a BGA package, decrease of package warpage in the temperature range where the package is used is a key issue in order to enhance the reliability of solder connection and to reduce the number of defective packages. If we can predict the package warpage accurately in the design stage of electronic packaging by using a simulation method, we can make use of such a prediction to enhance the reliability of electronic packaging. We need the material properties of silicon chip, molding resin and printed circuit board (PCB) used as a substrate to predict the package warpage. Among them, PCBs have multi-layered structures, and each layer has a complicated structure such as fine and high density wiring pattern. In the present study, we propose a method for predicting the thermal deformation of PCB using a finite element viscoelastic analysis, in which the complicated structure of each layer in PCB is taken into account. The apparent coefficient of thermal expansion (CTE) for PCB calculated from the proposed method is compared with the experimental results to show the effectiveness of the proposed method. Furthermore, it is shown that the warpage of a package consisting of a silicon chip and a substrate (PCB) can be predicted using the apparent CTE of PCB.

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This paper presents the theoretical solution of a two-dimensional isotropic medium (matrix) which has two circular elastic inclusions under the In-Plane problems. Using this paper, we provide the problem which has uniform stresses at infinity. This analysis is based on the complex variable method applicating Airy Stress Function and Mobius transformation. Using these solutions, several numerical examples are shown by graphical representation.

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Electromagnetic acoustic transducer (EMAT) is applied to resin cure monitoring in manufacturing process of fiber reinforced plastic (FRP) by resin transfer molding (RTM) method. The RTM is suitable for fabrication of FRP products of three-dimensional complex shape. In order to reduce the cost by minimizing the cycle time, cure monitoring is required. Authors have already ensured that the EMAT can detect the resin flow front in RTM process by monitoring the change in reflection coefficient at mold surface due to resin impregnation. The reflection factor is also affected by the resin viscosity. In this study, during the curing process, we measure the attenuation coefficient of standing wave introduced in the mold. Results are compared with impedance of dielectric sensor located inside the mold, showing that the degree of cure can be evaluated by EMAT at outer surface of the mold.

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Heat resistant coatings have been used in gas turbine blades and combustors. The resonance ultrasound spectroscopy method by the needle-transducer tripod was expanded to high temperature measurement in order to clarify the all directional Young's moduli of heat resistant coatings. The resonance spectrum was measured up to 1073K by the equipment with induction heating and remote sensing by laser-Doppler interferometry, which was originally developed. Following results were obtained from the measurement of atmospheric plasma sprayed CoNiCrAlY coatings: The in-plane Young's modulus increased with a decrease in the size of spraying powder. On the contrary, the out-plane modulus decreased. It meant that the anisotropy of the elastic modulus became remarkable with a decrease in the size of spraying powder. The enhancement of Young's modulus by thermal treatment was much significant in out-plane direction than in-plane direction. Consequently, the anisotropy of the elastic modulus became insignificant and negligible in the case of the thermally treated coating with large spraying powder.

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It is examined by numerical calculation how to detect crack wave radiating from a fluid-filled crack in a finite test piece of the rock, emphasizing the application to geometrical characterization of a geothermal reservoir crack. Boundary Integral Equation Method is employed for the numerical calculation. It is revealed that resonance of the test piece and stimulation e.g., hitting by hammer to stimulate the crack, have strong effect on radiation pattern from a crack in a finite test piece. In the case of large stiffness due to contact between the asperities on the upper and lower surfaces of the crack, it is difficult to detect the crack wave. In the case of measuring crack wave on the surface of the test piece, it is better for measuring that the surface of the test piece is near the crack surface. If surface of test piece is not near the crack surface, higher modes of crack wave are veiled in resonance of the test piece and stimulation.

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When a crack is detected in a stainless steel pipe during in-service inspection, the limit load criterion given in the codes such as JSME Rules on Fitness-for-Service for Nuclear Power Plants or ASME Boiler and Pressure Vessel Code Section XI can be applied to evaluate the integrity of the pipe. However, in the current codes, the limit load criterion is only provided considering pressure and bending moment. The torsion moment is not considered, although torsion moment does exist in the nuclear power piping system. In this paper, finite element analyses are carried out for stainless steel pipe containing a circumferential surface crack under the combination of bending moment and torsion moment, considering different pipe dimensions and flaw sizes. Based upon the analysis results, a plastic collapse estimation method is proposed considering the existence of the torsion moment and its magnitude, and this method make it possible to evaluate the integrity of the pipe for general loading conditions.

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Many examinations to evaluate the fatigue life reduction of structural materials of nuclear power plants in water simulating LWR coolants have been carried out. At the same time, the effects of several parameters on the fatigue life reduction have been determined quantitatively, since the first paper was published in Japan. Based on these results, the method to evaluate the fatigue damage for the materials exposed to the LWR coolant was developed. The MITI Guidelines (2000) and the TENPES Guidelines (2002) were issued for evaluating environmental fatigue damage at actual plants. The Environmental Fatigue Evaluation Method (EFEM) for Nuclear Power Plants (JSME S NF 1-2006) was established in the Codes for Nuclear Power Generation Facilities published by the JSME after reviewing the equations for the environmental fatigue life correction factor, F_<en>, and the evaluation techniques based on the updated knowledge at the time. The EFEM revised version has been drafted by incorporating the updated knowledge and is scheduled to be issued by the end of 2009. This paper introduces the outline of the revised JSME Codes and their technical bases concerning the effects of several parameters on the fatigue life reduction in the LWR coolant environment.

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Under mixed-mode conditions, the crack opening displacement and the sliding displacement seem to be suppressed by the crack surface contact behavior in the relative sliding between the upper and the lower sides of the crack. Especially, the crack surfaces of the fatigue crack with a compressive residual stress tend to contact each other owing to the crack closure. Therefore, it is important to evaluate the effect of the crack opening and the sliding suppress behavior quantitatively. In this study, forces that suppress the crack opening and sliding were calculated along the crack using FEM analysis. Nodes of crack edges in a FEM model, simulating the length and slanted angle of the crack in the examined specimen, were fixed to be equal to the displacement mesured by using the image correlation method. The resulting reaction forces evaluated on the nodes in the FEM model are equivalent to the crack opening and sliding suppress forces. However the fluctuation of the evaluated force is too large to estimate the effect of the crack opening and the sliding suppress behavior. Accordingly, the method to decrease the fluctuation is proposed by selecting the displacement fixed node, which seems to be the crack opening and the sliding suppressed point. As a result, the fluctuation of the evaluated force decreased and the crack sliding suppress force seems to be caused by the crack surface contact. On the other hand, the crack opening suppress force was equivalent to the residual stress measured by the X-ray.

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This paper deals with the initial crack growth path description emanating from an inclusion and the fatigue life prediction due to repeated rolling/sliding contact on the elastic half-space, accompanied by frictional heat generation. The stress intensity factors are analyzed for the surbsurface crack which is curved from the inclined initial main crack emanating from an inclusion. Rolling/sliding contact is simulated as a Hertzian contact pressure and a frictional load with heat generation which moves with constant velocity over the surface of the half space. The complex variable formulation of Muskhelishivili is used to reduce the problem for the inclusion and kinked crack to the simultaneous Fredholm integral equation of the second kind. This integral equation is solved numerically, thus the stress intensity factors of a kinked crack emanating from an inclusion in a half space can be calculated. Using the maximum energy release rate criterion, the crack growth path can be described. The associated fatigue life also can be predicted by making use of the crack growth law which is assumed by rotating bending fatigue test. The effects of frictional coefficient, slide/roll ratio and the depth of the inclusion on the crack growth path and associated life are considered for a high carbon-chromium bearing steel.

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In late years a study of advantageous high Si hard-drawn wire is pushed forward in comparison with oil tempered wires on a cost side. In this study, influence of the minute notch which gave it to rotary bending fatigue strength of the high Si hard-drawn wire and influence of the shot peening were investigated. The test bar which we gave shot peening treatment and notch to was prepared, and each hardness, residual stress, fatigue strength were investigated. A Nakamura-type rotary bending fatigue testing machine was used in fatigue test. SEM was used for fracture surface and organization evaluation. The fatigue limit of shot peening materials rose 45% in comparison with untreated material. When the linear notch of the 30 degrees〜90 degrees notch angle was given, in the case of notch angles less than 60 degrees, the fatigue limit of untreated material and the electrolytic grinding material became equal to smooth specimen. Influence of the wire drawing structure is considered as a reason.

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Nuclear power plant components are occasionally subjected to excessive load by earthquake and may suffer plastic strain. Although the plastic strain introduced in materials increases the strength, it may reduce the fracture toughness. In this study, the effect of the plastic strain on strength of cracked components was investigated. Firstly, the change in the tensile properties and fracture toughness due to plastic strain were examined for Type 316 stainless steel and carbon steel (SM 490). The degree of nominal plastic strain was 5%, 10%, 20% and 40% (only for stainless steel). Secondly, the J-integral values of surface crack on a pipe were evaluated by finite element analyses. Finally, the critical load for fracture of the cracked pipe was evaluated for various pipe and crack geometries using the J-integral values and the fracture toughness obtained. It was concluded that the plastic strain enhances the fracture strength of the cracked components when the induced plastic strain is less than 10%, although the extremely large plastic strain could reduce the strength.

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A cylindrical tube with a corrugated surface in the axial direction has excellent energy absorption characteristics as an automobile impact-absorbing part. In this study the difference in the deformation mode between the analysis results using the finite element method (FEM)and the experimental results by evaluating the actual cylindrical tubes was investigated. It was shown that the difference was caused by initial irregularities such as size error and was able to be predicted by nondimensional load incline in the load-deflection curve. Moreover, we tried to propose theoretical equations to predict mean load that is important for design of the impact-absorbing part and showed it was necessary to consider influence of work hardening on the theoretical equations.

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Fuel cell is regarded as a highly efficient power generation system as well as low-pollution. In particular, SOFC (Solid Oxide Fuel Cell) has high generation efficiency. However, a crucial issue in putting SOFC into practical use is the establishment of a technique for evaluating the deterioration. We have previously developed a technique to measure the mechanical damage of SOFC using Acoustic Emission (AE) method. This paper applied the kernel Self-Organizing Map (SOM), which is an extended neural network model, to AE data observed from damage progress on SOFC to produce a cluster map reflecting similarity of AE waves. The obtained map visualized the change of occurrence patterns of similar AE waves showing four phases of damage progress. The interpretation of the result as physical phenomenon is limited at this stage, though our methodology provides a common foundation for comprehensive damage evaluation system as well as monitoring.

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The purpose of this study is to construct a head physical model with actual human shape by using CAD/CAM technologies, in order to clarify head injury mechanism such as diffused axonal injury (DAI) under rotational impact. The head physical model was constructed from CT images of a subject, which consists of the parts reconstructed the skull, falx, cerebrospinal fluid (CSF) and brain. The skull model was processed from the 3D CAD model by using five axis machining. The falx celebri part was attached to the skull model. Moreover, the brain model, including complex structure and shape of the actual human head such as cerebral sulci, gyrus, and ventricles, was constructed by curing silicone gel in the mold processed by stereo-lithography. Finally, the gap between the skull and brain model was filled with water to simulate relative rotational motion of the skull and brain. Severe rotational acceleration corresponding to the occurrence of AIS5 head injury was applied around saggital axis of the model. As the results of the experiments, shear strain concentrated near the corpus callosum in depth of brain, where focal lesion is observed in grade II DAI. The result has not showed in other physical models with simplified the shape and construction. Therefore, a head physical model reconstructed a real human shape is needed to clarify the mechanism of brain injury due to rotational impact.

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Structural design optimization has become an effective paradigm for designing and developing various kinds of products. However, it is not so popular in the electric appliances in spite of their small sizes and relatively simple configurations. This paper first reviews the design and development processes of electric appliances in which CAE-based design and optimization based design methods were to be utilized. It reveals that the identification of design specifications is fairly important as their prerequisites in the field of electric appliances. Then this paper proposes a strategic scheme for systematically identifying specifications for structural design optimization. The scheme is composed of Specification Priority Matrix (SPM), for identifying the antipathetic importance of feature, cost, time and reliability, Failure Mode and Condition Specification (FMCS), for extracting, categorizing and identifying failure modes and their critical ones, Design Approach Tree (DAT), for selecting an appropriate design approach based on the result of SPM and FMCS, etc. Finally, its effectiveness and validity are discussed by studying the past design and development cases.

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Local cyclic slip behavior around an oblique fatigue crack tip in single-crystalline Fe-3.2wt.%Si alloy is precisely observed by using cross-sectional transmission electron microscopy (TEM). The observation successfully reveals the existence of different dislocation structures (vein, ladder, labyrinth, cell) around the crack tip. The results clearly suggest that the crack growth is strongly related to the formation of dislocation cell structures. Additional fractographic observation suggests that the crack growth, the path of which is found to be the boundary between hard cell region and soft matrix, accompanies the formation of striation pattern along the boundary.

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