One-sided fastening bolt using the plastic buckling of a pipe which is annealed along the length is studied in this paper. In fastening process the pipe is buckled to form a bulb in the annealed area under an axial compressive load from the bolt and the formed bulb can be used as the backside head of the bolt. Since the pipe geometry is the single design variable for the strength of fastening system, estimations of effects of geometrical parameters of pipe on buckling process and fastening process are very important. The whole fastening process is studied by the nonlinear finite element analysis consistently. Effects of the pipe length on the formed bulb and load in buckling process and the deformation behavior and load is fastening process are investigated for two different diameter pipes. Buckling and fastening experiments are carried out to verify the simulation method proposed. Numerical results are compared with experimental results for load and deformation modes in buckling and fastening process, showing fairly good coincidence. Three different types of deformation modes in fastening process are found in the analyses and experiments. Under the mode which has a large area contact to the bolt head, the fastening strength can be introduced rapidly and the high fastening strength is expected.

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The thread joint has been frequently used for the efficient productivity and maintainability as a machine element. However, many troubles such as loosening of bolted joints or fatigue failure of bolt were often experienced. Many attentions must be paid on the improvement of the strength and the reliability of the thread joints. It is generally said that the fastening axial force rapidly decreases by the rotation loosening of nuts if the relative slippage on the interfaces between nuts and fastened body goes beyond a certain critical limit. This critical relative slippage (S_<cr>) that prescribes the upper limit for preventing the loosening behavior has been estimated according to the theoretically obtained equation considering the bending deformation of bolt and the geometrical constraint condition. In this paper, we present the investigated results of the deformation behavior of bolt-nut joint under transverse loading condition. The bending moment of bolt is measured by the quasistatic loading test. The reaction force moment by nut used in the equation for estimating the S_<cr> is evaluated by the comparison of experimental and analytical results from estimated equation. The new equation for estimating the reaction force moment which agrees with measured value is examined and proposed.

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Most of machines and products have many joint portions (e.g. fastening, welding and adhesive joints) for the efficient productivity and maintainability. Especially, the thread joint has been frequently used for these purposes. However, troubles such as loosening of bolt and fracture or failure at joint portion have often arisen, thus many attentions have been paid on the improvement of the strength and reliability of the thread joint. In this paper, we present the investigated results of the sliding and the loosening behavior of bolt-nut fastener under the transverse loading condition. Firstly, the critical relative slippage (S_<cr>), less than the displacement in which the thread joints can keep the fastening, is experimentally obtained from cyclic loading test. When the relative slippage exceeds S_<cr>, the Fastening preload rapidly decreases. Then, this critical relative slippage is estimated according to the theoretically obtained equation considering the bending deformation of bolt and the geometrical constraint condition. The inclination compliance (k_w) that represents the pseudo-rigidity at the bolt head portion in this equation is evaluated by comparing the experimental result with the corresponding analytical one. In consideration of the nonlinearity of k_w with respect to the Fastening preload, the critical relative slippage is well determined by the formula for arbitrary Fastening preload.

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We experimentally investigated forces working on contact interfaces between metal and resin of resin mold structures, which are made of metal cylinders covered with resin mold. The results are discussed from the viewpoints of friction force, adhesion force, and contact pressure based on residual stress. As a result, we introduce a new concept for treating adhesion coefficients. Moreover, we developed FEM modeling for forces acting on the connected interface. The effectiveness of our method was verified by results showing that the calculation results obtained for the forces are in very good agreement with the measured results when the method was applied to the design of actual industry products, such as an insulation rod.

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Plain fatigue, fatigue crack growth and fretting fatigue tests of Al alloy (Al2024-T4) in air and in vacuum were carried out using a fatigue testing machine with SEM for in-situ observation. Fretting fatigue strength in vacuum was higher than that in air, while it was lower than plain fatigue strength in vacuum. High tangential force in vacuum would result in earlier fretting fatigue crack nucleation. However, high fatigue crack growth resistance would take dominant role for higher fretting fatigue strength in vacuum.

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For the purpose of investigating the structural behaviors and leakage characteristics of actual JIS pipe flange with flat metal gaskets, the leak pressure measurements using the homemade leak detector were conducted under the bolting up loads and internal pressures. In addition, the numerical analyses by finite element method (FEM) were carried out by using 3-D solid and gap elements for the load conditions in experiments. The followings are found for the tested flange and flat metal gaskets: Owing to the rotation of flange, bolt axial loads at initial bolting up are decreased with increasing internal pressures, which is characteristic of this kinds of gaskets. The surface stresses on gaskets are distributed in the way of definitely increasing toward circumference. The leak pressures are increased with increase in the bolting up loads, and their levels are dependent on kinds of materials, width and thickness of gaskets. The hardness of gasket materials will be related with the leak tightness. The obtained leakage characteristics will be useful as basic data in the practical seal design of the flange joint structure.

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This paper presents Efficient Boundary Element Method for Analysing Target Region, which is developed by Yamagishi, et al. to efficiently compute unknown quantities only in a specific domain extended to 2D elastostatic problems. In this method, whole boundaries are devided into Neighborhood Boundaries which are near to Target Region and Distant Boundaries which are sufficienty far from it. We set up boundary integral equations whose source points are placed on all the elements of the Neighborhood Boundaries and express these integrals which contain the unknown quantities on the Distant Boundaries as low order multipole moments by using a multipole expansion of the fundamental solution. Then, we set up boundary integral equations whose source points are placed near to Distant Boundaries by the increment of those multipole moments and express these integrals which contain the unknown quantities on the Distant Boundaries approximately as the multipole moments by using a generalized inverse matrix. Thus the number of unknowns and boundary integral equations set up are decreased drastically by this method. When unknown quantities are required only in a specific domain, especially on large-scale boundary value problems, this method enable us to compute them efficiently. The capability of this method extended to 2D elastostatic problems is verified with some numerical experiments.

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Higher performance large scale integration (LSI) requires copper (Cu) instead of aluminum (Al) as a wiring metal because of its superior electrical conductivity. These LSI also requires lower dielectric constant to decrease line-to-line capacitance. Recently, porous low-k dielectrics are introduced for low-k dielectrics because of its ultra lower dielectric constant. However, their poor mechanical strength causes fractures of low-k dielectrics during Chemical Mechanical Polishing (CMP) process. Therefore, it is important to keep the mechanical strength of porous low-k dielectrics during increasing porosity. In this paper, we studied the mechanical strength and dielectric constant of porous low-k dielectrics by finite element method and U^* method. The U^* method expresses a degree of connection between a loading point and an internal arbitrary point. The effects of porosity of porous low-k dielectrics on the mechanical strength and dielectric constant were discussed.

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The stress intensity factor of a finite specimen with an unsymmetrical crack initiated from a hole due to tension was calculated. The geometric stress intensity factor of this specimen with the cracked hole was compared with that of a center cracked plate, whose length was equal to the sum of the diameter of the hole and length of the crack. R_F was defined as the ratio of these geometric factors, where the nondimensional diameter of the hole a/W is less than 0.2 and R_F is less than 1.1 after the crack growth length c/W reaches 0.1. 2a, 2c, and 2W are the diameter of the hole, length of the crack from the edge of the hole, and width of the plate, respectively. Therefore, the stress intensity factor of a plate with cracks initiated from holes on its surface can be approximated within 10% error by the stress intensity of a center cracked plate when a/W is less than 0.2, though cracks initiated from edges are unsymmetrical. When a/W is larger than 0.3, R_F becomes larger than 1.1 across a wide range of c/W. Further, the stress intensity factor of a finite plate with an unsymmetrical crack was calculated. Under the calculation conditions employed in the present study, the stress intensity factor of the plate with the unsymmetrical crack could also be approximated within 10% error by that of the center cracked plate.

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This paper describes a method for stochastic homogenization analysis of a particle reinforced composite material. Since it is difficult to apply the homogenization-based perturbation method using the finite element method to a stochastic homogenization problem with considering a microscopic geometrical random variation in a microstructure, the equivalent inclusion method is used for the perturbation-based stochastic homogenization analysis. In using the equivalent inclusion method, each perturbation term for a random variation in a material property, size of inclusions or their volume fraction can be computed analytically. This fact shows applicability to apply the proposed method to a stochastic homogenization problem considering the microscopic geometrical random variation. At first, formulations for the proposed method are introduced. Next, the proposed method is applied to several kinds of numerical examples. From the numerical results, validity and accuracy of the proposed method are confirmed.

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In this paper, an elastic modulus of honeycomb consisting of hexagonal cell is studied by using numerical results of FEM. Based on the shape change of hexagonal cell an explicit equations of the equivalent elastic modulus C_<i2> (i=1, 2, 3) for the honeycomb whose cell wall is parallel to y axis are proposed. And, a method of calculating other elastic modulus by coordinate transformation is shown. Also, elastic modulus for various shapes of hexagon, obtained by changing systematically regular hexagon is investigated. It is found that compliance C_<yy|max>, which is maximum of elastic modulus C_<yy> in the one round turn of the coordinate system, varies in the systematic shape change, however, it always takes a minimum when the shape being regular hexagon.

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In this paper, a contact analysis of the anisotropic elastic half-domain was performed using a surface Green's function considering surface stress and surface elasticty. Fast Fourier transform (DC-FFT) method and conjugate gradient (CG) method were used for conducting the contact analysis. Displacement field calculated from the surface Green's function was compared with that in molecular dynamics analysis which an atom was set on the surface. The displacement in MD was similar to that in Green's function at z=0.2nm from the surface. A contact analysis for a spherical indenter with the radius of 4nm and a flat surface of the anisotropic elastic half-domain was firstly performed, and then indentation modulus was obtained. The load-penetration depth curves for MD and the present analysis were compared, and the present result considering surface stress and elasticity was agreement with those for MD. A contact analysis was conducted for investigating the effect of the material anisotropy on the penetration depth for the indenters of four kinds, elliptic, Knoop, Berkovich and Vickers. The indenters were rotated with respect to the z-axis. It was found that the penetration depth for elliptic and Knoop indenters demonstrated the effect of material anisotropy for the indenter orientation, although, Berkovich and Vickers indenters little showed.

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Characteristics of residual thermal stress field at the vertexes of two interfaces in three-dimensional joints with three layers are investigated using eigen analysis formulated by FEM and BEM using fundamental solutions for two-phase materials. Angle between two side surfaces at the vertex is varied from 30° to 150°. An expression for stress field near the vertex on the interface is firstly derived from the result of eigen analysis. The order of stress singualrity decreases with the increase of the angle. Angular functions corresponding to stress components are deduced from eigen analysis. A coefficient in the power term of angle from side surface in the angular function is a function of the angle between side surfaces and the value of coefficient increases with the increase of the angle between side surfaces. A coefficient of power term in stress distribution for the distance from the vertex has an extremum at 90° of the angle between side surfaces. It was found that stress singularity field at the vertex with a weaker singularity is affected largely by that at the vertex with a stronger singularity. There are two factors which define a stress singularity filed near the vertex; 1) the intensity of singularity defined by the distance from the vertex, 2) an angular function defined by the distance from stress singularity lines. The intensity of singularity at the veretx of interface was defined considering those factors. The value of the intensity of singularity at the vertex increases with the increase of the angle between side surfaces.

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Indentation technique was applied to evaluate the viscoelastic characteristic of a polymeric material. In addition, time-temperature superposition principle was used to obtain the master curve of the viscoelastic characteristics. In the present stydy, load controlled indentation test with a Berkovich indenter was performed on Polypropylene (PP). The results showed that the measured penetration depth exhibits typical creep behavior of viscoelastic materials. The viscoelastic and plastic deformation can be separated from the measured penetration depth through the shape measurement of impression by using AFM. Creep compliance estimated by the viscoelastic deformation are in good agreement with that obtained by tensile creep test. Moreover, the master curves evaluated by indentation and tensile creep test were corresponding over a wide range of the reduced time. This fact means that indentation is useful technique for the measurement of viscoelastic characteristics of polymeric materials.

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In general, internal cells are required to solve elastoplastic problems using a conventional boundary element method (BEM). However, in this case, the merit of BEM, which is ease of data preparation, is lost. Triple-reciprocity BEM can solve the two-dimensional elastoplasticity problems with a small plastic deformation. In this study, it is shown that three-dimensional elastoplastic problems can be solved without the use of internal cells, using the triple-reciprocity BEM. An initial stress formulation is adopted and the arbitrary distributions of the initial stress for elastoplastic analysis are interpolated using boundary integral equations and internal points. This interpolation corresponds to a thin plate spline. The fundamental solutions for this analysis are shown using polyharmonic function with volume distribution. The theory is expressed using a few fundamental solutions. In this method, strong singularities in the calculation of stresses at internal points become weak. A new computer program was developed and applied to solving several problems.

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Several atomic level problems such as uneven oxidation film or generation of lattice defects take place in the fabrication processes of nano-meter order devices. Among them, dislocation accumulation is a serious problem. Generation and accumulation of dislocations are known to take place during the cooling processes of device fabrication due to its thermo-plastic deformation. Dislocations accumulated in the electron channel have an enormous effect on the electronic state of the device, increase the signal delay and obstruct devices from normal operation. Therefore, it is important to understand the deformation and the dislocation accumulation for the fabrications of nano-mater order devices. On the other hand, impurity doping is an indispensable process for the device fabrication, and also important in dislocation accumulation. In this study, we make numerical models of ULSI cells where impurities are doped at some limited areas. Dislocation accumulation in the models during cooling processes of device fabrication is analysed by employing a technique of crystal plasticity analysis and evaluate the thermal stress, plastic slip deformation and accumulation of dislocations when the temperature drops from the initial value of 1000℃. Possibilities for the control of dislocation accumulation in impurity doped-ULSI cells are discussed.

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In order to clarify the influence of high pressure hydrogen gas on mechanical damage in a rubber O-ring, the fracture analysis of the O-ring used for a sealing material of a pressure hydrogen vessel was conducted. The O-ring was exposed twenty cycles to hydrogen gas at 100MPa. All the cracks observed in this study emanated from the interior, which can be classified into two types, type 1 and type 2, from the viewpoint of the location of crack initiation and the direction of crack growth. The type-1 cracks started from the center of the O-ring, while the type-2 cracks started from the sites near the surface of the O-ring. It is implied that tensile stress by squeezing influenced crack initiation and growth of the type-1 cracks. The mechanical damage by the type-1 cracks was more serious than that by the type-2 cracks. Stress analysis was conducted by the nonlinear FEM; then fatigue crack initiation of the O-ring was evaluated in terms of the maximum principal strain criterion, which has been widely employed for the evaluation of fatigue strength of rubber materials. The strain generated by squeezing was considerably smaller than fatigue fracture strain although the increase in the strain due to swelling was considered. It is considered that the type-1 cracks initiated and grew due to strain concentration caused by bubbles which were formed from supersaturated hydrogen molecules after decompression in addition to the strain due to squeezing and swelling.

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Finite element analysis was carried out to evaluate the distribution of stress along the fillet on an upper deck of cylinder block during the operation of diesel engine. The dynamic stress by cyclic combustion was analyzed taking into account the equilibrium of force acting in the main body assembly and cylinder head bolts in addition to their relative displacement condition. Preliminary analysis was firstly carried out to evaluate the stiffness ratio of cylinder head bolt and the main body assembly. The ratio was used for the main stress analysis of cylinder block. The main analysis was conducted for test and prototype engines. Their specifications are almost same except for the tightening position of cylinder head bolt. The following results were obtained. The distribution of stress during operation was not axisymmetrically but varied depending on the relative location against the outline of cylinder block and cooling water jackets. The results also agreed with the measured stress values. The amplitude and mean of stress obtained by the present analysis plotted on the fatigue limit diagram corresponds to the presence or absence of crack initiation along the fillet of test and prototype engines.

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Fatigue crack propagation tests using a single-crystalline Fe-3.2wt.%Si alloy are conducted for the purpose of investigating the effect of hydrogen gas on cyclic slip around the crack tip. The crack propagation rate is found to be larger in hydrogen gas than in non-hydrogen (helium) gas. The fracture surface and the near-tip cross-section of {110} crack are observed in detail by using a scanning electron microscope (SEM) and a transmission electron microscope (TEM), respectively. The observation reveals that, in helium atmosphere, the propagation is attributed solely to a ductile plastic rocess. In hydroen atmosphere, the propagation can be also attributed to a ductile plastic process except that the amount of plastic deformation is small and the cyclic slip is concentrated around the crack tip region. Different types of slip systems are found to be operative in helium and in hydrogen gas atmospheres, which is postulated to be correlated to the slip concentration and the increased propagation rate.

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Rotating bending fatigue tests were carried out for a squeeze cast Al alloy AC4CH-T6, in order to investigate the effects of hydrogen in molten aluminum and ambient humidity on fatigue properties. The hydrogen contents examined were 0.22 and 0.38cc/100gAl. The humidity tested was 25% and 85% of relative humidity. Voids were increased with increase in hydrogen content. However, static strength, ductility and fatigue strength were hardly influenced by hydrogen content. On the other hand, the fatigue strength was affected by humidity, especially the crack growth was accelerated by high humidity. In all cases, most of fatigue life was occupied by the growth life of a small crack which was evaluated by the small crack growth law.

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In this study, in order to calculate dangerous volume at various stress distribution, the dangerous volume quantification method is proposed. And in order to predict stress distribution of spray coating, an easy calculation method of residual stress distribution based on the first report is proposed. The calculated dangerous volume in alumina's spray coating on titanium layer is different from alumina's spray oating single layer. The difference is based on stress distribution in alumina's spray coating. The fracture strengths predicted with the proposed method and the third report are appropriate to experimental results obtained by 4-point bending tests. Therefore dangerous volume calculation in thermal stress distribution that is different from mechanical stress distribution also become possible.

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It is difficult to analyze theoretically the dynamic fracture of concrete block because it is discontinuous fracture behavior. In this research, the impact fracture when the impact body collides with the concrete blocks is analyzed by using the Distinct Element Method (DEM). DEM is suitable for the analysis of the fracture behavior from the continuous body to the discontinuous body. In this analysis, the impact body size, speed and mass are changed, the fracture behavior as crack length, the penetration length, the destruction area in the concrete block, are clarified. From the results, the efficient method breaking the concrete block is drawn.

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The partial safety factor (PSF) method with failure assessment diagram (FAD) is incorporated in fitness-for-service (FFS) guidelines such as API579 and SINTAP because it can evaluate crack-like flaws in service quantitatively and easily. Although API579 leaves the variance of yield stress out of consideration, it effects on PSF for strength of materials such as stainless steels, which have strong ductility. In addition, PSFs vary according to the variance of parameters used in evaluation. In this paper, we have evaluated the effect of the variance of parameters, especially of the applied stress and yield stress, on structural reliability and PSFs. As a result, the PSFs used for the evaluation of crack-like flaws must be calculated for each variance of the applied stress. The same PSFs can he used for the evaluation regardless of the variance of the yield stress in the brittle fracture dominant region. On the other hand, in the plastic collapse dominant region, the PSFs must be calculated for each variance of the yield stress. If the variance of the yield stress is ignored, unallowable crack-like flaws can be mistaken as allowable.

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A method of producing straight channels in aluminum is proposed. Hot extrusion of cylindrical billets containing aluminum powder with resin inserts is examined. First, it is found that aramid inserts successfully act as a space holder, which thin down without breakage during extrusion. The aramid inserts are burned out in the subsequent firing process, and the penetration in the extruded bar is confirmed. Secondary, the influence of different extrusion conditions on the extruded profiles is investigated. The reduction in diameter of the aramid inserts varies in a certain extent, but its average is almost stable under the test conditions. Thirdly, material test of the single aramid fiber is conducted to compare its mechanical property with that of the aluminum matrix. The ductility of the aramid fiber is similar to that of the aluminum powder matrix during hot extrusion.

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The colonoscope is widely employed for cure of a large intestinal disease. However, the medical accidents such as large intestines perforation by an immature doctor is still increase, because insertion operation of the colonoscope is highly skillful. To solve this problem, We think that development of a training device is effective. We aim to verify whether the porcine large intestines are able to become substitute as the human large intestines. The tensile experiment and the punch experiment were conducted on 243 samples of 14 pigs. The tensile experiment showed that stress at break was 0.20±0.08MPa, and strain at break was 0.51±0.24, and Young's modulus was 0.42±0.22MPa, and the poisson ratio was 0.71±0.22. Imitative endoscope extended the porcine large intestines forward perpendicular direction from the surface. The results showed the porcine large intestines were perforated by 11.9±2.8N. All results showed that porcine large intestines were able to become substitute of human large intestines.

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