日本機械学会論文集 A編
Online ISSN : 1884-8338
Print ISSN : 0387-5008
59 巻, 562 号
選択された号の論文の23件中1~23を表示しています
  • 後藤 真宏, 三浦 篤義, 西谷 弘信
    1993 年 59 巻 562 号 p. 1413-1420
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    It is important to evaluate the scatter in fatigue life. In the present study, rotating bending fatigue tests of 0.21% C steel having three ferrite grain sizes were carried out respectively. The initiation and growth behavior of cracks which led to the fracture of the specimens were examined. The fatigue data were statistically analyzed, and the following results were obtained. The scatter in the crack propagation behavior at the stress close to fatigue limit is especially large. Such a large scatter depends on the behavior of microcracks whose length is about 8 times smaller than the grain size. However, the scatter in propagation behavior of cracks 8 times larger than the grain size is relatively small. Distributions relating to all phases of lifetime can be expressed by the two-or three-parameter Weibull distribution. The coefficient of variance CV vs σaw relation for these distributions can be individually expressed as a narrow band independent of ferrite grain size.
  • 真壁 朝敏, 兼城 英夫, 玉寄 博道, 屋富祖 建樹, 屋良 秀夫
    1993 年 59 巻 562 号 p. 1421-1428
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    Fatigue crack propagation behavior under the mixed-mode condition which combined modes I, II and III was investigated in a push-pull fatigue test of the notched specimen. The notch inclined in the thickness direction was cut at the center of the plate specimen. Some fatigue cracks were initiated from the notch root, and the interaction of these cracks was observed in the crack propagation stage. However, in the present study, the crack length including notch length was treated as a single-center crack. The fatigue crack propagation rate da/dN was evaluated with effective stress intensity factor range ΔKp, eff calculated using projected crack length and normal stress in the axial direction. The crack propagation law for the present notched specimen evaluated with ΔKp, eff coincides with that of the center cracked plate.
  • 大路 清嗣, 辻 昌宏, 久保 司郎, 小野 嘉雄, 八幡 篤, 梅井 健司
    1993 年 59 巻 562 号 p. 1429-1436
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    A criterion was sought for predicting the path of a fatigue crack in HT80 steel propagating in residual stress fields. The problem was investigated with respect to two questions : (I) which was the dominant factor in determining the fatigue crack path, the cyclic components or the maximum values of stress intensity factors (SIFs), and (II) what kind of criteria, expressed in terms of the foregoing dominant SIF parameter, could be used for predicting the fatigue crack path ? For the first question, it was indicated that the cyclic components of SIFs determined the crack path. For the second question, it was found that the crack path could be predicted by applying the Δσθ maximum criterion, which predicted that the crack propagated in the direction of the maximum range of circumferential stress component. Crack propagation lives for cracks curved due to the existence of a hole were calculated by applying the "U- (crack opening ratio) estimation" method based on the superposition principle proposed by the present authors. The predicted lives were in good agreement with the experimental results.
  • 御厨 照明, 北岡 征一郎, 杉浦 義孝
    1993 年 59 巻 562 号 p. 1437-1442
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    The crack propagation rate da/dN at the specimen surface or db/dN toward the inner direction perpendicular to the specimen surface and crack opening displacement COD of a mode I small surface crack in a round bar are examined under biaxial stresses by means of the combination of plane bending and cyclic torsion. When the stress intensity factor range ΔK* at the deepest point of the crack periphery is the same, db/dN increases with the decrease in biaxial stress ratio C. An analogous tendency is recognized in the relationship between da/dN and ΔK at the specimen surface. A unique relationship is obtained between da/dN and crack tip opening displacement CTOD in spite of C. Thus, it can be concluded that the main factor which controls da/dN is CTOD.
  • 竹園 茂男, 垰 克己, 青木 隆, 稲村 栄次郎
    1993 年 59 巻 562 号 p. 1443-1450
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    An analytical method for the elasto/visco-plastic deformation of axisymmetrical thin shells subjected to thermal loads due to fluid is developed. First, the temperature distribution through the thickness is assumed to be curves of second order, and the temperature field in the shell under the appropriate initial and boundary conditions is determined using the equations of heat conduction and heat transfer. Secondly, the stresses and deformations are derived from the thermal stress equations. The equations of equilibrium and the relations between the strains and displacements are derived from the Sanders elastic shell theory. For the constitutive relations, the Perzyna elasto/visco-plastic equations which consider the temperature effect are employed. The fundamental equations derived are numerically solved using the finite difference method. As a numerical example, a simply supported internal pressure cylindrical shell made of aluminum under thermal loading due to fluid is analyzed, and the variations in displacements and internal forces with time are discussed.
  • 佐々木 克彦, 石川 博將
    1993 年 59 巻 562 号 p. 1451-1457
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    A unified constitutive model which allows prediction of cyclic plasticity, uniaxial and biaxial ratchetting, creep, and stress relaxation is required in the design of aeronautic equipment, nuclear reactors, etc. Detailed experimental observation considering viscoplastic behavior of materials must be carried out to construct a unified constitutive model. In this paper, uniaxial and biaxial ratchetting tests and creep tests were carried out at both room temperature and at 550°C using SUS 304 stainless steel. As a result, it is clear that uniaxial ratchetting behavior is affected by the viscous deformation of the material, and that biaxial ratchetting behavior is affected by both the viscous deformation of the material and the deformation caused by nonproportional loading.
  • 郭 智宏, 渡部 修
    1993 年 59 巻 562 号 p. 1458-1466
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    The present paper gives a finite-element formulation for largely deformed elastic-plastic structural analysis in order to study the effects of the constitutive equation utilized on numerical simulations. The general framework of the constitutive equation for large strain and rotation problems is based on hypoelasticity, where either Jaumann or Green stress-rate is assumed. As for the plastic hardening rule, the internal time theory is employed, which can be regarded as a combined nonlinear isotropic/kinematic hardening plasticity model retaining the concepts of 'yield surface' and 'normality rule.' Numerical examples of plane block subjected to shear deformation show the fundamental features of mechanical response affected by the employed consititutive equation.
  • 渡辺 一実, 大好 直
    1993 年 59 巻 562 号 p. 1467-1474
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    Propagation of antiplane SH wave in an anisotropic elastic half space is discussed. The plane surface does not coincide with the principal axis of the anisotropy, that is, the off-angled surface. The present paper composed of three parts. The first is the discussion of the power flow direction of SH wave, second is that of the reflection coefficient at the off-angled surface. The last part gives exact closed-form solutions for the transient and steady-state responses of the half space to a line antiplane load. Results obtained here are very basic, however, they would be useful for researchers of nondestructive inspection in the field of composite materials.
  • 村上 進, 渡辺 一実
    1993 年 59 巻 562 号 p. 1475-1481
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    Propagation of the SH wave in a layered half space is considered. Reflection and transmission coefficients at an imperfectly bonded interface are analyzed with use of the ray expansion technique. This paper defined the bonding strength at the interface as Joint Coefficient Dz. It is shown that the SH wave in the half space is governed by the first and second reflected waves. When the bonding at the interface is strong, the first reflected wave contributes to the reflection energy. When the bond is weak, however, the second reflected wave contributes to the energy. The shutting energy in a dissimilar plate is also obtained. The energy is very sensitive to the strength of interface bonding, when the wavelength is short.
  • 村上 進, 渡辺 一実
    1993 年 59 巻 562 号 p. 1482-1489
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    Propagation of P wave (longitudinal wave) in layered half space is considered. Reflection and transmission coefficients at an imperfectly bonded interface are analyzed. The bonding strength at the interface is assumed as Joint Coefficient Dx and Dy, which represent tangential and normal direction joints of the jointed plane, respectively. The energy of reflected and transmitted wave is very sensitive, and resonance of the plate occurs for short wave lengths. It is more remarkable for small incident angles. When the bonding strength is strong, reflection and transmission coefficients show very complex variations. The relation between the two coefficients and bonding strength is also discussed.
  • 村上 進, 渡辺 一実
    1993 年 59 巻 562 号 p. 1490-1496
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this paper, SH (horizontally polarized shear) wave propagation in an inclined anisotropic elastic body is investigated. It is analyzed as a basic boundary value problem as the interface between an inclined anisotropic half space and an isotropic half space. Direction of wave propagation is determined by the use of power flow density. It is shown that power flow density determines the direction of the principle axis of an inclined anisotropic body. Reflection and transmission coefficients in the interface are also discussed. The reflection coefficient in the interface is large when inclined angle in large.
  • 戸伏 壽昭, 林 萍華, 服部 丈晴, 牧田 昌之
    1993 年 59 巻 562 号 p. 1497-1504
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    The cyclic deformation behavior of a TiNi shape memory alloy wire and of a helical spring for the martensitic transformation and the R-phase trasformation was investigated experimentally. The main results are summarized as follows. For cyclic deformation associated with the martensitic transformation, the transformation stress decreases and the trnasformation temperature rises. The amounts of variation in the stress and temperature are large in the early number of cycles and are small after about 20 cycles. For cyclic deformation associated with the R-phase transformation, the transformation stress and transformation temperature vary slightly. For cyclic deformation of a helical spring, the recoverable elongation is very large in the region of the R-phase transformation. The recovery deformation and recovery force of the helical spring under cyclic deformation vary slightly even in the region of the martensitic transformation.
  • 菅野 良弘, 片岡 誠治, 田中 喜久昭
    1993 年 59 巻 562 号 p. 1505-1513
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    The plane-strain thermoelastic problem in a hollow circular cylinder of functionally gradient material (FGM) is formulated in terms of a stress function taking into account the temperature-dependent properties of the material. The formulation is achieved by deriving the conditions necessary for the assurance of the single valuedness of rotation and displacements in a hollow circular cylinder with arbitrary nonhomogeneities and temperature-dependent properties of material. Numerical analysis by the finite difference method to show a use for the proposed formulation is presented for PSZ (partially stabilized zirconia) / SUS 304 (type 304 stainless steel) FGM and PSZ / LCS (low carbon steel) FGM circular cylinders subjected to unaxisymmetric transient heating on the inner boundary surface. The significance of the temperature-dependent properties of material to the thermoelastic material design of FGM is quantitatively discussed.
  • 森 昌彦, 近藤 充
    1993 年 59 巻 562 号 p. 1514-1518
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    The authors have attempted to develop an analytical method to estimate the variability of life evaluation in a structure under thermal load by treating the variations in the heat transfer boundary conditions around the structure using the stochastic finite-element method. This article describes the formulation of the variability of solution used in the analytical method, and then shows the results of benchmark analysis with the general purpose FEM code "MARC" to confirm the accuracy of the analytical method. The variability of life evaluation is also shown as an example in order to demonstrate the validity of this method.
  • 菅野 良弘, 中馬 康晴
    1993 年 59 巻 562 号 p. 1519-1525
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    Light-weight, high-strength and high-stiffness composite materials are becoming increasingly important in high-performance structural design, such as in aerospace engineering. Since these materials exhibit degradation of both strength and stiffness under a hygrothermal environment, there is an urgent need to accurately estimate hygrothermal stresses in the composite materials. In this paper, a formulation in terms of a stress function is presented for a hygrothermoelastic problem in a multiply connected region, by deriving new integral conditions necessary for the assurance of the single-valuedness of rotation and displacements. A closed-from solution as an application of the proposed formulation is given for the hygrothemoelastic problem in a hollow circular cylinder made of T 300/5208 subjected to unaxisymmetric steady-state hygrothermal loading on the inner boundary surface. Numerical calculations of the distributions of temperature, moisture and hygrothermal stresses are carried out for the cases of various hygrometric and thermal loading conditions and various ratios of the outer radius to the inner one of the cylinder.
  • 曹 岩, 高橋 賞
    1993 年 59 巻 562 号 p. 1526-1531
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    There are many experimental methods for the determination of the stress intensity factor K in the vicinity of the crack tip. The caustics method for estimating the stress intensity factor of two-dimensional cracks has been investigated theoretically and experimentally, and provides a technique for easily obtaining the value of K. However, relatively few theoretical and experimental analyses for orthotropic material using this method have been conducted. In this paper, the optical method of caustics is extended to evaluate the stress intensity factor K for an orthotropic material theoretically and experimentally, and the range of applicability of this method is clarified. In this study, we make a comparison between the orthoropic and anisotropic material, and a plate of "Fiber Reinforced Plastics" (F. R. P. ) is used.
  • 今村 仙治, 佐藤 和郎
    1993 年 59 巻 562 号 p. 1532-1536
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper presents a study of yield points of mild steel which utilized solid and hollow cylinders with a transverse hole under torsion. The maximum tensile stress was found at an intersection of hole and outer surface of the cylinder by observing the torsional fracture face of polymethly methacrylate (PMMA). This analysis has been carried out with the surface layer theory applied to the maximum shear stress which occurred at the edge of the hole in an infinite plate subjected to pure shear. The analytical results coincided well with the experimental data in the following points. (1) Yield points of cylinders depend only on hole diameter and are free from the influence of the outer diameter and the ratio of inner to outer diameter of cylinders. (2) There are two kinds of yield points with respect to the diameter of the hole. In the case of a hole with a comparatively small diameter, the yield point is independent of the hole diameter of the cylinder.
  • 神谷 修, 熊谷 一男, 望月 良康
    1993 年 59 巻 562 号 p. 1537-1542
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    Anisotropic fracture toghness (Ev) of austenitic stainless steel weld metal containing various levels of nitrogen has been investigated. In the case of high nitrogen content, Ev values indicated an anisotropic property in weld metal, while in the case of low nitrogen content, Ev was isotropic. When the weld metal contained 1606 ppm nitrogen, the value of Ev of the specimen which was parallel to the columnar structure was 1.4 times that of the one which was vertical to the columnar structure. The origin of anisotropy was related to the change in microstructure. The nitrogen promoted the formation of a columnar structure vertical to the weld center. The cleavage readily occurred parallel to the residual ferrite existing boundary of the columnar structure ; therefore, the fracture toughness indicated anisotropy. The ferrite volume fraction (A), the morphology factor (S) and the anisotropic factor (Rθ) were measured by a computr-aided image analyzer. The anisotropic fracture toughness values (E) were estimated by the equation E = (A·S·Rθ)-0.187.
  • 奥野 澄生, 大村 慶次, 河合 末男, 河野 俊一, 正井 健太郎, 笠井 靖夫
    1993 年 59 巻 562 号 p. 1543-1549
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    Fatigue strength evaluation methods for spot welding are studied by the fatigue test of an actual car body. The following results were obtained from the test. (1) The configuration of fatigue fracture on spot welds around the window corner near the supported point of a car body is in fair agreement with those of structural component models of the window corner. (2) The abovementioned fatigue strength of spot welds can be evaluated by (a) the carrying-load values of spot welds based on FEM analysis and by (b) the values of typical stresses measured around the spot weld. Judging from the test results, it was proven that the fatigue strength of spot welds in an actual car body against cyclic load can be estimated by the results of the fatigue test of test pieces and structural component models which were previously reported by the authors.
  • 松山 秀信, 坂元 宏規, 柴田 公博
    1993 年 59 巻 562 号 p. 1550-1555
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    Transformation hardening was performed on S40C steel by a linear polarized CO2 laser beam without the use of any additional absorbent coating. The depth and width of the hardened zone were measured at different incident angles of the beam. In addition, the relationship between the heat input of the laser beam and the characteristics of hardened zone, such as depth and width, was investigated by finite-element analysis. Absorptivities at different incident angles during laser hardening were deduced by comparing the relationship between the laser power and hardened depth, which was determined experimentally, with the relationship obtained by calculation. A pronounced absorptivity peak of approximately 58% was observed during laser hardening in air when the incident angle was approximately 74°. Absorption characteristics were also deduced in a different atmosphere. The results were compared with absorption characteristics calculated theoretically or measured calorimetrically to investigate the influence of surface temperature and oxidization on absorptivity. It was found that the peak absorptivity value increased when surface temperature rose or oxidization occurred.
  • 竹内 則康, 岸本 喜久雄
    1993 年 59 巻 562 号 p. 1556-1561
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    An efficient boundary element computational technique for use with the elastic sliding contact problem is developed based on the penalty function method. In this problem, it is sufficient that two contact conditions, that is, slip and opening states on the contact region, are considered. The contact coditions are introduced to the virtual work function with penalty coefficients and the integral equation is discretized using an ordinary basic equation of the boundary element method. In order to demonstrate the practical applicability of the present method, contact problems of a thermal print head and a platen roller are analyzed and the results are compared with those obtained using the conventional method.
  • 青木 繁, 天谷 賢治, 富樫 潤
    1993 年 59 巻 562 号 p. 1562-1567
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    A method for estimating the galvanic corrosion rate was developed. In the case where the electrochemical polarization curves of metal in the electrolyte considered are available, the galvanic corrosion rate can be estimated by solving us Laplace equation with boundary conditions based on the polarization curves. The polarization curves, however, are not always available. In this case, it is necessary to estimate the density of the current across the metal surfaces from the potential values measured at some points far from the metal surfaces. This inverse problem was formulated by employing the boundary element method. Since the system of linear equations obtained was ill-conditioned, direct application of conventional numerical procedures to the equation system results in an oscillatory solution. In this paper, at first the method which estimates the relationship between potential and current density was applied. In order to improve the accuracy, a new method using apriori information which as expressed as fuzzy membership functions was developed. A sample problem was solved by the new method in order to demonstrate the accuracy.
  • 坂本 二郎, 尾田 十八
    1993 年 59 巻 562 号 p. 1568-1573
    発行日: 1993/06/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this paper, an optimization technique for layout of truss structures using the genetic algorithm (GA) is proposed. It is difficult to obtain the global optimum for layout problems using the traditional gradient-based algorithms, because of the discontinuity and nonconvexity of the design space in these problems. By contrast, the genetic algorithm based on the principle of genetics and natural selection is efficient for such problems, since it makes it possible to obtain the global optimum and comparable near optimums simultaneously without using function gradients. We proposed a hybrid method combining the genetic algorithm and the generalized optimality criteria method in order to optimize the layout and cross-sectional area of truss members simultaneously. The hybrid method is adopted in the minimum weight design of the truss structures subjected to displacement constraints in which the optimum combination of truss members should be determined. From the result of numerical examples, the efficiency and reliability of the hybrid method using the genetic algorithm are discussed in comparison with the member elimination strategy starting from the ground structure.
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