Epoxy resin used for electronic parts is transformed from the liquid to the solid by the chemical curing reaction, in this case, the residual stresses and the residual strains are caused in epoxy resin. Then, electronic parts become defective due to these stresses and strains. In this report, the strains caused by the chemical curing reaction and thermal load for laminated beam consisting of epoxy resin and steel were examined from both sides of experiment and theory. As a result, it was clarified that the strains generated in the laminated beam could be indicated by the sum of the bending strain caused by warp deformation and the compressive strain caused by the shrinkage of epoxy resin, and that the contribution ratio of each strain and the simple predicting equation based on theory in common use were proposed.

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In this paper, the elastic-plastic collapse of T-shaped joints subjected to torsional loading is studied by using the finite element method. The effects of a hole existing in the main tube are investigated. Especially, it is found that when there is no hole in the main tube, the maximum torsion moment M_<peak> is equal to that of the corresponding pure tube, however, when there is a hole, the maximum torsion moment becomes smaller and changes with the width ratio B/b. The cause of the maximum torsion moment fall is because of a deformation δ_z in z-direction of the upper surface of the main tube. In order to evaluate the influence of the hole quantitatively, parameter G_d showing the geometric characteristic of joint was defined, and a loss ratio μ of the maximum torsion moment is given as a function of G_d.

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Spatial structures as being observed in cellular solids behave a wide variety of elastic deformation. In particular, some types of bending-dominated structures might produce the potential deformation mechanics exerted by the rotational manners of flexible joints. In this paper, we propose some of two-dimensional microstructures constructed of four-coordinate flexible joints and elbowed beam members, and conduct the numerical analyses and uniaxial tensile tests, using the really manufactured frameworks, for evaluating the Poisson's ratios of the proposed structures. The elastic properties obtained by the real model, which cover the considerable ranges of Poisson's raios dependent on joint flexibilities, correspond well to those by numerical results. In addtion, the out-of-plane deformation of a certain rigidly jointed structure is newly found from the present experiment.

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When subjected to external forces, bolted joints behave in a complex manner especially in the case of the joints being clamped with multiple bolts. Friction type joints are widely used for the joints subjected to shear loads. Bearing type joints, which support the shear load on the surface of bolt body, are used less frequently, since its mechanical behavior is too complicated to accurately estimate the load capacity. In this study, mechanical behavior of multi-bolted joints subjected to shear loads is comprehensively analyzed by three-dimensional FEM. Load distribution patterns of the bearing type joint are compared to those of the friction type joint. It has been found that the shear load, which is applied to the bearing type joint, distributes with a concave shape along the load direction as the number of bolts is increased and a fair amount of the shear load is supported by friction. Additionally, a simple method that calculates the shear load distribution is proposed using elementary theory of solid mechanics, which can estimate the shear load distribution with sufficient accuracy for the case of small friction coefficient.

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This paper is about improvement of diagnostic accuracy of the damage identification applying the generalized linear mixed model to the inverse problem. Generalized linear mixed model (GLMM) is the extend method of the linear regression analysis include the random effect. By the method, relation between the dependent variable and the independent variables are divided to fixed effect and random effect. The fixed effect means true relation and the random effect means the unknown fluctuation because of the individual specificity. When the damage diagnosis conducted by the inverse problem, this unknown fluctuation is caused by not only the difference of the lot of test piece, but also the unknown parameters of the damage. For example, for the damage size identification problem, location of the damage is the unknown parameter. This unknown parameter is unknown at the time of damage identification but this unknown parameter is known at the time of constructing the model of the inverse problem and the time of deciding the parameter for the inverse problem model. Then in this research, improvement of diagnostic accuracy of the damage identification using inverse problem via the GLMM is conducted. The method is applied to the delamination identification via electric potential method of CFRP laminate. FEM analyses are conducted to obtain electric potential changes due to delamination crack creations with seven-electrode type specimens. By comparisons of the estimations without the random effect and with the effect, a better diagnostic tool is discussed in detail. As a result, GLMM improve the diagnostic accuracy of size and location identification of the delamination crack.

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To obtain a reasonable prediction of fatigue life under variable loading, it is important to understand the damaging process. In this study, the damage process of low-cycle fatigue was investigated for Type 316 stainless steel. Fully-reversed axial fatigue tests were conducted in ambient air at room temperature by controlling strain amplitude, which was 6% at the maximum. Two-step strain tests were also conducted in order to assess the effect of loading history on fatigue life. The fatigue life was shown to be not always longer than that estimated using a linear damage accumulation rule. Furthermore, in order to evaluate the effect of initiation and growth of surface cracks on the fatigue life, the surface layer of specimens was removed after the first step. The fatigue life was extended by surface removal, although it was not recovered completely. Many internal cracks were observed on the fractured surface of the surface-removed specimens, and in some cases the specimens were fractured by these internal cracks. It was concluded that the low-cycle fatigue damage of Type 316 stainless steel consisted of three factors: surface cracking, internal cracking, and strain accumulation.

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This paper presents the results of a study on the notch effect in low cycle fatigue of Mod.9Cr-1Mo steel under multiaxial loading. Tension-torsion multiaxial low cycle fatigue tests were carried out at room temperature using three types of circumferential notched specimens of the steel and crack initiation, failure and propagation lives were experimentally obtained. Two proportional and three nonproportional strain paths were used in low cycle fatigue tests. The crack initiation and failure lives decreased with elastic stress concentration factor but the crack propagation lives slightly decreased with it in push-pull low cycle fatigue. The superposition of torsion straining on push-pull loading caused a reduction of the three lives but they little decreased with elastic stress concentration factor. The three lives in nonproportional loading became smaller than those in proportional loading but showed smaller reduction with elastic stress concentration factor. Local strains at notch root were estimated by Neuber's rule and maximum principal strain, the equivalent strain of ASME Code Case and the path strain were applied for predicting the low cycle fatigue crack initiation and failure lives. The ASME strain range was most suitable for the prediction of crack initiation life and the three strain range gave almost the same accuracy for the prediction of failure life.

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Since film materials used in electronic devise are often loaded from various directions, the crack initiated in such devises seems to propagate to various directions with bending. Therefore, it is important to consider about the fatigue crack propagation behavior under mixed-mode conditions with the crack opening and the crack sliding displacement. It this study, by using a new fatigue testing method in which the film was bonded to the cyclic loaded base plate with the inclined ellipsoidal through hole from the loading axis, the fatigue crack propagation behavior was discussed under mixed-mode conditions for a thin copper film. From the FEM analysis, stress on the film was uniform and principal stress direction was inclined from the loading axis of the base plate. Mode I and mode II stress intensity factors at the bent fatigue crack tip were calculated by using a displacement extrapolation method. As a result, the bent fatigue crack was initiated from the precrack and the crack propagation direction was almost perpendicular to the principal axis for an annealed copper film. On the other hand, the bent crack inclined to the rolling direction for cold rolled copper film with crystal grains extended to the rolling direction.

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Crack propagation behavior under combined stress state of cyclic bending and static torsion is investigated for A7075 aluminum alloy. The propagation direction and the propagation rate of a fatigue crack that occurs from a small hole machined at the specimen surface are affected by a static shearing stress. Especially, the crack propagation rate increases by the existence of a static shearing stress. If the maximum stress intensity factor obtained by using equivalent alternating stress Σ_a and equivalent static stress Σ_m is used for arranging the crack propagation rate, all data fall on the almost same curve. Crack opening displacement at the crack tip perimeter increases by the existence of a static shearing stress. The opening component of a static shearing stress is considered to be responsible for this result. If the crack opening displacement behind 50μm from crack tip is used for arranging the crack propagation rate, the unique relation is obtained regardless of the presence of a static shearing stress.

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A mixed-mode thermoelectroelastic fracture problem of a functionally graded piezoelectric material (FGPM) strip containing two parallel axisymmetric cracks, such as penny-shaped or annular cracks, is considered in this study. It is assumed that the thermoelectroelastic properties of the strip vary continuously along the thickness of the strip, and that the strip is under thermal loading. The crack faces are supposed to be insulated thermally and electrically. Using integral transform techniques, the problem is reduced to that of solving two systems of singular integral equations. Systematic numerical calculations are carried out and the variations of the stress and electric displacement intensity factors are plotted for various values of dimensionless parameters representing the crack size, the crack location, and the material inhomogeneity. The following facts can be found from the numerical results. The normalized intensity factors are under the great influence of the geometric parameters. The effect of the material inhomogeneity on the intensity factors depends on the geometric parameters

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In hydraulic turbine runner, accidents due to fatigue often occurs. In this study, in order to clarify fatigue properties and mechanism of fractures on cast steel SC49 used as hydraulic turbine runner aged 45 years, tension-compression fatigue tests were carried out for the cast steel cut out from the turbine runner surface layer and inside. The results are summarized as follows: (1) The S-N curve of aged SC49 has large scatter although it shows the tendency of the right going down. And also it is found that the fatigue strength of inside part has larger scatter than that of surface layer part. (2) From SEM observation of the fracture surfaces, crack initiation sites were found to be the casting defect which consist of dendritic phase and pore. (3) It is possible to evaluate the fatigue life of aged SC49 by using the casting defect size (area)^<1/2> and the initial stress intensity factor calculated by defect size. The value of the threshold stress intensity factor obtained in this study were 4.8MPa・m^<1/2>. (4) The extreme statistics distribution of casting defect size of surface layer was different from that of inside part. The estimate method of the largest defect size in the structural element using the former distribution was suggested.

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The FPB (Fine Particle Bombarding) process attracts attention as a new surface-preparation technique. The influence of surface modification by the FPB process on various characteristics of SUP10 was investigated. The surface roughness of FPB treatment materials decreased more than shot peening treatment materials. As a result of comparing the shot time of FPB process, it proved that surface roughness increased as the shot time became long. On every projection conditions of FPB process, the hardness near the surface rose higher than the shot-peening. Hardness was the maximum at the time of shot time 20 seconds, and residual stress was the maximum at the time of 5 seconds. The maximum compressive residual stress was a value equivalent to a shot-peening process. The fatigue strength of the FPB material rose than shot-peening material by low surface roughness and high surface hardness. These results showed that a FPB process was effective in the improvement in fatigue strength of spring steel.

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Cu alloys used for recent rocket combustion chambers are exposed to severe conditions, i.e., high temperature environments with oxidizing followed by reducing. Therefore, it is very important to understand the effects of such severe environments on their mechanical properties for maintaining their integrity for a long time. In this study, in order to investigate the effect of internal oxidation on mechanical properties, Cu-Cr-Zr alloy was subjected to the oxidation test at 825℃ for 15h and then the small punch (SP) test specimens (φ3.0×0.25t[mm]) were removed from the resultant internal oxidation layer. Some of SP specimens were exposed in the high temperature and high pressurized hydrogen gas atmosphere (7.6MPa, 600℃, 24h) for hydrogen-charging. The SP tests were applied to the oxidized and the hydrogen-charged specimens at the temperatures ranging from room temperature to 600℃. Experimental results revealed that Cr and Zr were preferentially oxidized along grain boundaries and Cr precipitates were also selectively oxidized in the grains by the internal oxidation. The strength and ductility of oxidized specimen gradually decreased with increasing testing temperature accompanying intergranular brittle fracture, although the internal oxidation had almost no influence on the mechanical properties at room temperature. Additionally, the degradation of mechanical properties was more pronounced by the hydrogen-charging, especially, in room temperature.

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Influence of interlayer thickness on stress fields at a vertex in three-dimensional adhesive joints with three layers is evaluated using eigen analysis and boundary element method (BEM) using fundamental solutions for two-phase materials. A model for analysis is three-layered joints consisting of Si, resin and FR-4.5. A relationship between singular stress fields and the interlayer thickness is precisely investigated. All stress components are expressed in spherical coordinate systems in which origins are located at the vertex of each interface. Expression for stress, δ_<θθ>, near the vertex on the interface is firstly derived from the result of eigen analysis. The order of singularity for Si-resin interface is larger than that for resin-FR-4.5 interface. A coefficient of the power-law term in the stress expression for the distance from the vertex increases as resin thickness, the interlayer thickness, increases. The coefficient is demonstrated an upper limit when the resin thickness is larger than the width of the model. Value of coefficient in the power-law term of the angular function derived from BEM is a constant near that derived from eigen anlaysis for angular function on Si-resin interface. Three-dimensional intensity of singularity at the vertex of interface in three-dimensional joints is defined considering the intensities of singularity for radial direction and the angular function. Variation of the three-dimensional intensity of singularity at the vertex with the resin thickness is similar to that of the intensity of singularity for the radial direction.

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Actin filament, the most abundant component of the cytoskeleton, plays important roles in fundamental cellular activities by dynamically changing its structure by elongation, branching, and bundling. These dynamic structural changes are regulated by various types of actin-binding proteins, whose binding is primarily determined by their approach behavior toward the filament. These molecular-level phenomena occur on spatial and temporal scales, relevant to diffusions of the molecules as well as filaments by thermal fluctuations in the cytoplasm. Therefore, to better understand the actin filament dynamics, this study narrowed down a target on this spatiotemporal scale with the aim of modeling and simulating the approach behavior of binding proteins toward the actin filament in the solvent. As a representative binding protein, we focused on the Arp2/3 complex; one of the binding proteins known to initiate filament branching. In the model based on Brownian dynamics, the actin monomers and the Arp2/3 complex were considered globular particles governed by the Langeven equation, and the solvent was described as a continuum. In the case of shorter filaments, simulation results revealed that the frequency of the Arp2/3 complex approaching the filament ends was significantly higher compared with the middle portion. Contrary to this, as the filament length increases, the frequency ratio of the filament ends decreases. These results indicate that the fluctuations enhance binding to the ends of shorter filaments, but when the filaments become longer, the frequency of binding to the middle of the filament increases, such as observed in the branching phenomena.

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