日本機械学会論文集 A編
Online ISSN : 1884-8338
Print ISSN : 0387-5008
68 巻, 665 号
選択された号の論文の25件中1~25を表示しています
  • 福岡 俊道, 許 全托, 吉田 健太郎
    2002 年 68 巻 665 号 p. 1-7
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    A bolted joint is frequently used under thermal load in practical applications, such as internal combustion engines, steam and gas turbines, pressure vessels, etc. In order to accurately evaluate the thermal stresses thus produced, the effects of thermal contact resistance at the interface and the heat flow through small gaps, which exist around the objective bolted joint, must be taken into account. An empirical equation, which can compute the thermal contact coefficient at the interface for various contact conditions, has been presented in the previous paper. In this study, a simple equation for evaluating apparent thermal contact coefficient is proposed, which can calculate the amounts of heat flow through small gaps. By incorporating the effects of such contact resistances, i.e., in case of two planes being in contact or with small gaps, into the finite element formulation, a numerical approach is proposed, which can elucidate how the bolt stress is varied with time under thermal load. It is shown that among various factors, coefficient of linear expansion has dominant effects on the variations of bolt stress.
  • 高木 知弘, 福岡 俊道
    2002 年 68 巻 665 号 p. 8-14
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    The most important factors for the leakage problem of pipe flange connection is considered to be contact pressure distribution at the gasket bearing surface in service. In this study, the mechanical behaviors of pipe flange connection are evaluated using FEM as a three-dimensional contact problem, in which a gasket is modeled as a nonlinear one-dimensional gasket element. Here, the contact pressure distributions at the gasket bearing surface and the variations of bolt stress are estimated under uniform bolt preloads or nonuniform ones due to the elastic interaction during bolting up. The numerical procedure proposed here can successively deal with the processes of bolt-up, applying inner pressure and applying bending moment. The analytical objects are pipe flanges specified in JIS B 2238 with compressed asbestos sheet gaskets being inserted. The validity of the numerical method is ascertained by experiment.
  • 尾田 十八, 王 安麟, 鐘 浩
    2002 年 68 巻 665 号 p. 15-20
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this paper, a local direct rule based on a new transition function of the Cellular Automata (CA) is presented. It is the structural optimization method by the Evolutionary Cellular Automata (ECA). The local direct rule uses the neighborhood states as the CA's input. The ECA is the CA optimized by the Genetic Algorithm (GA) for the certain problems. This new transition function makes to decrease drastically the degrees of local direct rule freedom depending on the number of the neighborhood cells. The design conditions of the structure are introduced as virtual cells to apply the same rule in all the design space. A local direct rule here is decided by the evolutionary calculation of GA. The method is applied to the minimum weight design problems and the adaptive solutions are obtained. From the results, it is observe that the local direct rule based on a new transition function is effective in the self-organization problem of the complex system.
  • 宮崎 則幸, 坂口 政嗣
    2002 年 68 巻 665 号 p. 21-25
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    A three-dimensional finite element computer program is developed for calculating dislocation density in bulk single crystal during Czochralski (CZ) growth process. In this program, crystal anisotropy in elastic constants and slip systems is taken into account. The Hassen-Sumino model is used as a uni-axial creep constitutive equation, which is extended to multi-axial stress state by using the theory of crystal plasticity. Dislocation density analyses of a silicon bulk single crystal are performed in the cases of both <001> and <111> pulling directions by use of this program. It is found that the dislocation density increases very rapidly from initial state to steady state. Significant differences are found between both pulling directions in distribution pattern of stress and dislocation density.
  • 村上 敬宜, 周 世栄
    2002 年 68 巻 665 号 p. 26-34
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    It has been reported that, according to some rotating bending fatigue tests, the S-N curve for high-strength steels consists of two straight lines. One corresponds to the line for short life at high stress level due to fracture from a surface origin, and another corresponds to the line for ultra-long fatigue life at low stress level due to fracture from internal nonmetallic inclusions. In this study, stress/strain concentration around inclusions is analyzed by FEM to seek a possible mechanism for this particular S-N curve behavior of ultra-long fatigue failure of high-strength steels for rotating bending fatigue test. A special focus is put on the growth of plastic zone around an internal inclusion and near surface with increasing applied nominal stress. Considering the different scale of plastic zone near surface and around an internal inclusion, it can be concluded that, in case of rotating bending fatigue test, fracture is likely to occur from a surface origin at high stress level and from an internal inclusion at low stress level. However, this characteristic depends on several factors such as specimen size, residual stress, cyclic yield stress, size and location of the crucial inclusion.
  • 江澤 良孝, / 佐竹 誉大, 山口 貴吏, Takashi YAMAGUCHI
    2002 年 68 巻 665 号 p. 35-40
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this paper, we describe a method for speeding up an iterative solver for structural analysis using parallel computers. We have improved the sparse matrix used in the factorized sparse approximate inverse (FSAI) method. The sparse matrix in the original method is derived from the matrix to be solved. However, in the sparse matrix that we have developed, we set the terms with minimum influence on the solutions to zero and set the terms with significant influence to a non-zero value. Using the new iterative method, we can obtain the solution in half the time of the conventional CG method. We tested the robustness of this new method into by applying it in shell analysis. The numerical results verified the effectiveness of this solver.
  • 古谷 佳之, 松岡 三郎, 高木 周作
    2002 年 68 巻 665 号 p. 41-48
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    Modified-ausforming have been proved effective for improvement of high-cycle fatigue properties in high strength steels. Three SCM 440 steels (heats B, C and D) with the tensile strength of 1600 MPa were supplied for fatigue tests. The heat D included larger Al2O3 inclusions than heats B and C. Heat B was ausformed and induction tempered, whereas heats C and D were normally quenched and furnace tempered. AFM microstructure observation showed that martensite blocks and carbides of the ausformed heat B were smaller than those of normally quenched heats C and D. Fatigue limits at 108 cycles were 890 MPa for ausformed heat B and 840 and 750 MPa for quenched heat C and D. Fish-eye type fracture, which occurred in the quenched heats, disappeared in ausformed heat B. Origins of fish-eye type fracture were TiN inclusions in quenched heat C and Al2O3 inclusions in quenched heat D. Large and clear ODA, i.e. optically dark area, was observed on the fracture surface around the Al2O3 inclusion. On the other hand, ODA around the TiN inclusion was obscure. The fact that fish-eye type fracture disappeared and a higher fatigue limit was achieved in the ausformed heat B have shown the good performance of ausforming in fatigue properties of high strength steels.
  • 沢井 達明, 木村 勇次, 津崎 兼彰, 竹内 悦男, 松岡 三郎
    2002 年 68 巻 665 号 p. 49-56
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    High-cycle fatigue properties up to 108 cycles were investigated for a modified-ausformed spring steel SUP 12 with the tensile strength δB=1772 MPa. The surface-type fracture occurred at the higher stress level. On the hand, some specimens had the fish-eye-type fracture origin at the inclusion, and others endured 108 cycling at the lower stress level. The fatigue limit at 108 cycles δw=900 MPa for the fish-eye fracture was higher than δ=886 MPa estimated from δw=0.5δB, which is the empirical equation for the surface-type fracture of ordinary quenched and tempered low alloy steels. The optically dark area was not found around the inclusion. Excluding the fish-eye-type fracture, the higher fatigue limit δw=1090 MPa for the surface-type fracture was expected. It corresponds to δW=0.62δB. It is concluded from these results that the modified-ausforming improves the fatigue properties for both surface and fish-eye type fractures of the high strength steel.
  • 小川 壽, 幡中 憲治
    2002 年 68 巻 665 号 p. 57-64
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    Fatigue crack initiation is caused by cyclic slip deformation in crystalline materials. Its mechanism, however, has not been clearly elucidated yet. In the present study, the surface of S45C steel which was fatigued under push-pull loading was observed by means of AFM ad then geometric configuration developed due to fatigue was measured with a high resolution. The center average height in the surface roughness increased greatly at the early stage of fatigue process and moderately increased in the following fatigue process, which occurs mainly in ferrrite portion of ferrite/pearlite microstructure. FFT analysis was achieved to examine a characteristic of geometric configuration developed on the surface of fatigued specimen. Consequently, it was found out that the power spectrum density is much greater in the frequency range corresponding to the grain size, and increases with almost the same distribution with respect to frequency as fatigue process progresses.
  • 邱 建輝
    2002 年 68 巻 665 号 p. 65-73
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    Effects of the stress amplitude and the test temperature on the fatigue property of rolled PP under the room temperature and the low temperature have been examined according to the variation of dynamic visco-elasticity factor during the fatigue process. The result shows that the un-uniformity of material property in the specimen section is improved by rolling processing and the E'falls off while the tan δ rises. Therefore, the material becomes much ductile and the crack due to the fatigue is restrained. Although a tendency of ductile fatigue fracture is found with the increase of the stress amplitude under low rolling ratios less than 40% and the fatigue life becomes short, the specimen stretches uniformly without rupture corresponding to all stress levels under high rolling ratios more than 60%. As the molecule orientation becomes strong the elasticity and the strength properties are improved. Experimental results demonstrate that the rolled PP specimen has a fatigue resistance much superior to the unrolled PP specimen.
  • 緒方 隆志
    2002 年 68 巻 665 号 p. 74-80
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    High temperature components are subjected to creep-fatigue loading where creep cavities initiate and grow on grain boundaries. Development of a quantitative evaluation method of cavity growth is important for reliable meintenance. In this study, a creep-fatigue test was carried out at 600°C on 2.25 Cr-1Mo steel in a scanning electron microscope and continuous observation of cavity growth behavior was made. Based on the cavity growth observation, previously proposed cavity growth models were modified and a simulation result by the modified model was discussed by comparing with observed cavity. From the observation, spherical shape cavities initiate and grow up to their length of 2 μm on the grain boundary at initial stage of damage and these cavites change their shape to crack-like to grow until their length reaches around 10 μm. Both spherical and crack-like cavity growth equations, which consider diffusion and power low creep as driving force under constrained condition, were derived. Measured cavity growth rate is well expressed by the derived equations and a cavity growth simulation result corresponds to the change in the maximum cavity size with cycles.
  • 旭吉 雅健, 坂根 政男, 能瀬 春雄
    2002 年 68 巻 665 号 p. 81-87
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper describes crack propagation behavior of SUS304 stainless steel, SCM435 steel and Al 1050 aluminum alloy under reversed torsion loading. Strain controlled low cycle fatigue and stress controlled high cycle fatigue tests were carried out to make clear the stress/strain dependency on crack propagation behavior using smooth, notched and through hole specimens. Main cracks propagated in the maximum shear direction at high stress/strain ranges and in the principal direction at small stress/strain ranges in SUS304 stainless and SCM435 steels smooth specimens. Main cracks propagated in the maximum shear direction in Al 1050 smooth specimens at all stress/strain ranges. Crack propagation direction was influenced by notches for SUS304 stainless and SCM435 steels but there was no influence of notches for Al 1050.
  • 能瀬 春雄, 坂根 政男, 山下 満男, 塩川 国夫
    2002 年 68 巻 665 号 p. 88-95
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper studies the crack propagation behavior of four types of lead and lead-free solders. Crack propagation tests were carried out using center cracked specimens of Sn-37 Pb, Sn-3.5 Ag-iCu, Sn-5 Sb, and Sn-7.5 Bi-2 Ag-0.5 Cu under push-pull straining at 313 K. Crack propagation rates of the solders were successfully correlated with cyclic J-integral range. The material dependency of crack propagation rate was discussed in relation with the observations of fracture surface and tensile property of the solders. Ductility of materials was suggested to have a significant influence on crack propagation rate but melting temperature has a small influence on the propagation rate.
  • 牛島 邦晴, 石田 佑輔, 陳 玳〓
    2002 年 68 巻 665 号 p. 96-103
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this paper, the plastic singular stress field for a crack normal to and meeting a bimaterial interface is studied by using FEM. In the analysis, it is assumed that both materials obey Ramberg-Osgood stress-strain formulation, and have different strain hardening exponent n. Detailed results for MODE I under plane strain are investigated. When n1 for the material with a crack is larger than n2 for the other material without the crack, the plastic singular stress field obtained by FEM is almost the same field obtained by asymptotic analysis. However, from the FEM result, it is found that a term which is independent of the distance r from the crack tip is included in the displacement field so as to satisfy the continuity of displacement along the interface. When n1 < n2, the plastic stress singularity exists near the crack tip, but the stress singularity cannot be described as a power-type singularity form.
  • 北村 隆行, 梅野 宜崇, 辻 長知
    2002 年 68 巻 665 号 p. 104-110
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    In order to derive the instability criterion of atomic structures, such as thin film and nano-tube, an analytical method is proposed on the basis of the energy balance against the deformation. Taking into account all degree of freedom for atoms in system, the criterion is given as the positiveness of determinant consisted of the second derivation of energy against the infinitesimal displacement. This method is available for any deformation mode of any atomic structure as well as for any form of interatomic potential. As an application of this method, the ideal tensile strength of thin film is analyzed in order to understand the effect of surface on the instability. Critical stress is successfully extracted by the proposed method combining with the molecular statics simulation. Ideal strength eminently decreases for the films with the thickness of less than 10 nm.
  • 田中 基嗣, 北條 正樹, 落合 庄治郎, 山雄 剛俊, 岩下 哲雄, 澤田 吉裕
    2002 年 68 巻 665 号 p. 111-118
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    The notched fracture strength using the double edge notched plate tension specimen of the woven C/C composite was calculated by the modified shear lag analysis method, in combination with the average stress criterion (composite fractures when the average stress over the characteristic distance in the fiber bundle at the notch tip reaches the strength of the fiber bundle). The present method could describe the following features experimentally observed in our former work. (i) The fracture strength was lower than the net strength criterion and decreased with increasing width when the debonding at the notch tip was short. (ii) The fracture strength was well estimated by the net strength criterion when the debonding was long. The results of calculation for wider specimens revealed the following; the notched strength remains nearly constant for any width given by the net strength criterion when debonding length is very long; it decreases with increasing width unless the debonding length is very long; the strength-width curve of the composite with finite debonding length is in the range of the upper bound given by the net strength criterion and the lower bound by the fracture toughness one.
  • 北村 隆行, 平方 寛之, 井辻 隆志
    2002 年 68 巻 665 号 p. 119-125
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    The stress concentration near interface edge dominates the delamination of thin films. The size of stress-concentrated region is dependent on the film thickness. As the film thickness is approaching 100 nm in an advanced LSI component, the region size is in the nano-scale. In this study, the delamination tests are conducted for multi-films, Cu/TiN, on a Si-substrate with different thickness of Cu (50 nm, 100 nm and 500 nm), and the effect of stress-concentrated region on the strength of Cu/TiN interface at the edge is examined. In the tests the stress-concentrated region is about 5 nm, 10nm, and 40 nm, respectively. In all experiments, the delamination crack initiates at the free edge of Cu/TiN interface. As the fluctuation of strength is small, the results are reliable. The stress distribution at the delamination reveals that the stress at the free edge is larger for thinner Cu film though it is reverse in the region of 20∼50 nm < r <300 nm (r: distance from the edge). Averaging the stress near the free edge, it is found that the delamination in all tests takes place when the stress at r <100 nm reaches about 18∼19 MPa. This signifies that the region of r <100 nm characterize the interface toughness and the size is larger than the stress-concentrated region in the specimen.
  • 瀧口 三千弘, 和泉 淳, 吉田 総仁
    2002 年 68 巻 665 号 p. 126-131
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    For single-lap joints of acrylic adhesive and aluminium adherends, tensile lap shear tests at various crosshead speeds, and also stress relaxation tests were performed at room temperature. In the tensile lap shear tests, it was found that the shear flow stress of the adhesive resin increased remarkably with increasing shearing speed. In the stress relaxation tests, the stress decreased rapidly at the early stage of the relaxation tests, and it gradually approached asymptotic stress values. In order to describe such rate-dependent deformation characteristics of adhesive resin, a viscoplastic constitutive model has been presented in this paper. The shear stress-strain responses, as well as stress relaxation behaviour, predicted by the present model agreed well with the corresponding experimental results.
  • 新舘 恭嗣, 関根 英樹
    2002 年 68 巻 665 号 p. 132-138
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    The Smoothed Particle Hydrodynamics (SPH) method is an evolving numerical technique for modeling many transient dynamic problems of large deformation, including high and hypervelocity impact problems. The SPH method employs no spatial mesh. The absence of a mesh leads to some nice features such as the ability to handle large distortions in a Lagrangian frame and consider the effects of voids. However, in the SPH calculation, numerical fracture can occur when the interaction among the particles disappears as a result of increasing distance among them. In this paper, the SPH method is improved in order to prevent the numerical fracture. The improvement of the SPH method is based on the concept that new particles are generated in the numerical fracture space. The improved SPH method is applied to analyze hypervelocity impact problems. The numerical results show that the present method can generate new particles without large influence on the surrounding region and prevent the numerical fracture effectively.
  • 河井 昌道
    2002 年 68 巻 665 号 p. 139-146
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    A multiaxial constitutive model that distinguishes between creep-damage behaviors of a class of polycrystalline metallic materials under tensile and compressive stress states is developed from phenomenological points of view. The formulation is achieved by modifying the coupled creep-damage model based on the von Mises stress criterion. The effective stresses of the von Mises type that control the rates of creep and damage are scaled, respectively, to show asymmetry in tension and compression. For this purpose, anisotropic scaling parameters are introduced which depend on the hydrostatic stress and the third invariant of the stress deviator. Two kinds of modified version of the coupled creep-damage model are presented which consider kinematic and isotropic hardening of materials, respectively. These new models describe the primary, secondary and tertiary creep behavior with asymmetry in tension and compression. Numerical simulations of creep behavior under constant and variable stress conditions are also carried out.
  • 河井 昌道, 益子 誉一
    2002 年 68 巻 665 号 p. 147-153
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    A constitutive model to describe the rate-dependent nonlinear behavior for a class of solid polymers is developed from phenomenological points of view. A particular emphasis is placed on a unified multiaxial formulation of viscoelastic and viscoplastic deformation of polymers. The constitutive model is based on irreversible thermodynamics and it is systematically derived from thermodynamic potentials, i.e., free energy and dissipation energy functions. A capability to describe the viscoelastic nature is incorporated into the present model through the Ziegler's thermodynamic reconstruction of the classical rheology models. The rate-dependent nonlinear viscoplastic behavior of polymers is described using the combined isotropic and kinematic hardening format of the Chaboche type. The effect of hydrostatic pressure on the viscoplasticity of polymers is also taken into account. The present model enables us to describe a rate-dependence of the initial tangent modulus, that of the flow stress in the subsequent nonlinear regime and a tension-compression asymmetry of the viscoplastic dilatational yielding of polymers. Validity of the present model is evaluated on the basis of stress-strain responses of a thermoplastic resin (PEEK) under different strain-rate conditions.
  • 谷本 光史, 河野 和清, 瀬戸 秀幸
    2002 年 68 巻 665 号 p. 154-160
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    A pair-roll system consisting of a rubber-covered roll and a driving metallic roll is often used in industrial machinery such as printing machines and paper-making machines. In this paper, a new finite element formulation of thermo-viscoelasticity is proposed to determine the stress and temperature distributions in the rubber layer in a steady-state rolling contact problem. In this approach, the time derivatives are converted to the higher order spatial ones by means of the Galilean transformation, resulting in no direct time integration. Heat Generation due to viscous energy dissipation and the strain-rate dependence of viscoelastic properties of the rubber are taken into account. To demonstrate the accuracy of the proposed method and its applicability to existing machines, numerical calculations for thermo-viscoelastic responses of a pair-roll system have been conducted, and the results have been compared favorably well with experimental ones.
  • 谷本 光史, 河野 和清, 高橋 定, 佐々木 将志, 吉田 総仁
    2002 年 68 巻 665 号 p. 161-168
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    The quality of a wound roll is highly dependent upon the in-roll stress distribution, which is controlled by the operating parameters of center torque, nip and tension. With increasing demands for higher performance of paper winding machines in terms of higher speed of winding, wider width of web and larger diameter of wound roll, it becomes of vital importance to determine the optimum operating conditions of the machines. In this paper, a new numerical formulation for paper winding is proposed taking account of the effect of nonlinearity in paper compressibility, air-entrainment and permeance. The proposed theory of winding is based on the assumption that the accumulation of the in-roll stress by a wound-on layer can be expressed as the superposition of the stress increment calculated from a mechanical model of a pressured thick cylinder. The theory of elastohydrodynamic lubrication with the compressibility of air is introduced to evaluate the effect of air-entrainment. Permeance of air is expressed under the assumption that permeance is proportional to the pressure difference of both sides of a paper. The numerical stress analysis of wound rolls shows the significant effect of the air-entrainment and permeance upon the in-roll stress.
  • 佐々木 克彦, 石川 博將
    2002 年 68 巻 665 号 p. 169-174
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper treated a series of experiments and simulations concerned with biaxial ratcheting behavior. The biaxial ratchetting tests were conducted using SUS304 stainless steel subjected to cyclic torsion with superposed axial tensile or compressive stresses. Experimental results showed that (1) the axial strain occurred due to even zero superposed axial stress, and (2) biaxial ratchetting strain due to the tensile superposed stress was larger than that due to the compressive superposed stress. The biaxial ratchetting behavior was simulated by a constitutive model based on a viscoplastic potential related to dislocation density. To explain the axial strain due to zero or nonzero superposed stresses, a constitutive model was proposed, where the effect of the latent hardening on the back stress was considered in the evolution equation of the back stress. The constitutive model successfully simulated the axial strain due to zero or nonzero superposed stresses. The difference of the biaxial ratchetting strain due to the tensile and compressive superposed stresses was also well explained by the constitutive model.
  • 佐々木 直哉, 斎藤 洋子
    2002 年 68 巻 665 号 p. 175-180
    発行日: 2002/01/25
    公開日: 2008/02/21
    ジャーナル フリー
    Molecular dynamics simulation was used to investigate wear models of frictional sliding between a pin and a carbon thin film containing nitrogen. In this simulation, we developed advanced Tersoff interatomic potential describing nonequilibrium atomic structures produced by the addition of nitrogen. A genetic algorithm is used to optimize many potential parameters that are fitted to the first principle cohesive energies of various systems, including bulk systems with amorphous, which are under stress. This optimization algorithm converges towards a set of potential parameters that well describe not only crystals but also amorphous systems. We examined the influence of content and distribution of nitride on the dynamics properties of wear atoms. These simulations show that wear is minimized when about 20 to 30 percent nitrogen is added. Also, simulation results correspond with the experimental results qualitatively.
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