日本機械学会論文集 A編
Online ISSN : 1884-8338
Print ISSN : 0387-5008
68 巻, 672 号
選択された号の論文の19件中1~19を表示しています
  • 細木 真保, 岡部 永年, 佐久間 俊雄, 岩田 宇一, 宮崎 修一
    2002 年 68 巻 672 号 p. 1149-1154
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this study, we proposed a new parameter in order to estimate the change of various transformation temperatures of which the alloy was subjected to either of the superelastic cycle and thermo mechanical cycle. The accumulated strain energy was defined as the recovery strain energy decreased up to an arbitrary cycle in Ti-Ni-Cu shape memory alloy. This study for a new parameter made it possible to estimate with unification the changes of the transformation temperature, which were greatly influenced by the stress field around the dislocation increased by cold working in the alloy. Therefore, it was found that the accumulated strain energy was possible to become a unified parameter expressing the change of the internal energy condition due to the cyclic deformation and transformation. We discussed about the results of analysis together with considering the effect of the cold work and shape memory treatment on the transformation temperature.
  • 王 燕建, 林 沛征, 平野 嘉一, 青砥 史明, 一之瀬 和夫, 小久保 邦雄
    2002 年 68 巻 672 号 p. 1155-1162
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    Load carrying capacity and energy absorption of plastic bulges of stepped pipes enlarged by dies at the edge are investigated in this paper. The pipes are enlarged by dies and then compressed axially on the edge in the experiment. Relations between load and displacement, and the deformation process of plastic bulge are examined in the experiments. The process of enlargement by a die and compression are simultaneously analyzed by finite element analyses. The load-displacement relations and the deformation modes predicted by finite element analyses are in good agreement with the experiments. The energy absorption ability in monotonic increasing load and cyclic varying load are also estimated by analyses. In the deformation process of a moving plastic bulge the constant load carrying capacity is obtained.
  • 高野 直樹, 木村 圭一, 座古 勝, 久保 太
    2002 年 68 巻 672 号 p. 1163-1169
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    In the development of functional ceramics, the study on the relation between the macroscopic properties and the microstructures has been a critical issue. However, it has not been made clear by many experimental works. On the other hand, this paper takes the computational mechanics approach using the homogenization method. To model the very complex microstructure architecture three-dimensionally, the image-based modeling technique is employed. A porous alumina with needle-like random pores with 3.1% porosity ratio is studied in this paper. The effect of the location of extracting the unit cell and its size on the homogenized elastic constants is investigated. Then, the predicted values were compared with the measured ones. As a result, a unit cell region expressed by one million voxel elements with 2μm resolution provides very accurate prediction regardless of the location of the unit cell in the random microstructures. The error between the numerical prediction and the measurement is only 1%.
  • 守時 一, 神谷 修
    2002 年 68 巻 672 号 p. 1170-1177
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    Ductile fracture in plate forging is analyzed. For the prediction of the fracture the criterion based on load instability is employed. The concept of load instability corresponds to the loss of load control which arises when the load deforming a material is imposed over the strength of the material and is brought as the stationary state of largest nominal stress component, s^^·1=0. This gives basic condition of load instability. When the basic condition is satisfied, in order to realize the occurrence of cracking the co-existence of plastic loading and unloading must be required, which gives the annexed condition of load instability represented as z^-L≤0. Hence, the criterion is composed of basic and annexed conditions. Stress and strain in a specimen are evaluated using FEM. The index z^-L is examined at s^^·1=0, and is obtained at a number of working conditions designating tool radius and friction coefficient between tools and a plate. These working conditions are divided into two regions according to the sign of z^-L. When z^-L is negative at a working condition the fracture is predicted in such working. It is found that load instability predicts cracking possibility lower than plastic instability.
  • 守時 一, 神谷 修
    2002 年 68 巻 672 号 p. 1178-1184
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    Reasonability of Storen-Rice method is discussed which is widely used for estimating the formability in stretch forming of sheet metals. One of the famous methods for analyzing localized necking had been proposed by Hill. But, the application of his analysis must be confined to the bi-axial forming where there is at least the direction t with no stretching, i.e., ε^^·u =0 in the forming sheet. Hence, this condition has been a serious obstacle for its application to the bi-axial stretch forming without fulfilling such condition. Storen and Rice proposed Δε^^·tt=0 in place of ε^^·tt=0, where Δ denotes difference between the regions separated by a necking plane. Moreover, in their analysis they imposed the equilibrium of traction rates acting between these regions. However, they ignored the necessity that these regions must be under a common boundary condition. We examine in this paper whether this necessity is satisfied or not in their method. Consequently, it is proved that it is not satisfied in general. Hence, their method cannot be reasonable for estimating the stretch formability of sheet metals.
  • 近藤 良之, 栄 中, 久保田 祐信, 工藤 隆夫
    2002 年 68 巻 672 号 p. 1185-1191
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    A small defect gives a substantial effect on the fatigue limit. The effects of mean stress and hardness on the fatigue limit of material with a small defect are quite different from those of a long crack nor a plain specimen. The following questions have been arisen. (1) Why does a harder material have a higher fatigue limit in case of material with a small defect? It is not a case in a long crack. (2) Is the mean stress effect on the fatigue limit of material with a small defect the same as that on the ΔKth of a long crack? Fatigue tests were performed under a wide range of mean stress for two kinds of steels with different hardness using specimens with small defects. The crack closure of a short crack was measured. It was shown that the build up of the crack closure was affected by the material hardness and mean stress. This behavior of crack closure resulted in peculiar properties of fatigue limit in case of material with a small defect.
  • 皮籠石 紀雄, 陳 強, 大坪 謙一, 燕 怒, 近藤 英二, 王 清遠
    2002 年 68 巻 672 号 p. 1192-1197
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    The fatigue properties of a nickel-base superalloy, Inconel 718, in long-life region up to 108 cycles were investigated under rotating bending at room temperature and elevated temperature of 300°C, 500°C and 600°C. S-N curves at 500°C and 600°C showed the stepwise shapes, though those in cases of room temperature and 300°C were the conventional one-step ones. All the fractures originated from the specimen surface at room temperature and 300°C, while the internal fractures occurred in long-life region beyond 107 cycles and the surface fractures at the stress levels over the horizontal line of S-N curves corresponding to the fatigue limit for the surface fracture at 500°C and 600°C. Intergranular crackings were observed at the origin of internal fracture.
  • 五嶋 孝仁, 石原 外美, 清水 理能, 吉田 博一, 土田 祐知
    2002 年 68 巻 672 号 p. 1198-1205
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper deals with the surface crack growth path description and the fatigue life prediction due to repeated rolling/sliding contact on the elastic half-space, accompanied by frictional heat generation and crack-face pressure. The stress intensity factors are analyzed for the surface crack which is kinked in multiple times from the inclined initial main crack. The rolling/sliding contact is simulated as a Hertzian contact pressure and a frictional load with heat generation, moving with constant velocity over the surface of the half-space. Applying the maximum energy release rate criterion to each kinked angle, the crack growth path can be described, and employing a mixed mode fatigue crack growth law, the associated fatigue life also can be predicted. The effects of frictional coefficient, slide/roll ratio and crack-face pressure on the crack growth path and associated life are considered for a high carbon-chromium bearing steel (SUJ 2).
  • 宮川 浩明, 佐藤 千明, 池上 皓三
    2002 年 68 巻 672 号 p. 1206-1211
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    Mesoscopic fracture toughness of epoxy matrix phase in unidirectional Carbon Fiber Reinforced Plastics (CFRP) in Mode I and Mode II loading was investigated using Double Cantilever Beam (DCB) specimens, End Notched Flexure (ENF) specimens and Raman spectroscopy. The strain distribution near the crack tip in the epoxy matrix phase was measured experimentally. A lead oxide (PbO) thin film was deposited on the measured surface of the DCB and the ENF specimen by physical vapor deposition (PVD) as the pretreatment for Raman spectroscopy. The Mesoscopic fracture toughness of the epoxy matrix phase in CFRP was determined using the measured results. It was also investigated using the Finite Element Method (FEM). These results coincided with macroscopic fracture toughness.
  • 藤本 由紀夫, 新宅 英司, PIRKER Gernot, 田中 義和
    2002 年 68 巻 672 号 p. 1212-1219
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this paper, a method to measure the stress intensity factor of a two-dimensional crack existing in a member of real structure is presented. The proposed method uses the following properties of piezoelectric materials; (1) isotropic piezoelectric material induces an electric charge which is proportional to the sum of stresses (σxy) on the structural member's surface; (2) the electric charge is also proportional to the integral of (σxy) in the area where the piezoelectric element is adhered to the structure. In order to obtain the stress intensity factors of Model I and Model II separately, two small pieces of piezoelectric elements are adhered near the crack tip so that the two piezoelectric elements are placed close to each other with the crack tip positioned between the piezoelectric elements. The electric current from the piezoelectric elements are integrated by the integration circuits and the output voltages which are proportional to the electric charge induced in the piezoelectric elements are measured. The stress intensity factors of Model I and Model II of the crack are estimated by the use of the measured output voltages.
  • 李 年慶, 坂根 政男
    2002 年 68 巻 672 号 p. 1220-1227
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper studies the multiple crack detection by a. c. potential method. Alternating currents from 200 Hz to 5000 Hz were applied to artificially cracked specimens of Incone 1738 LC superalloy having 1-5 cracks with 50-500 μm depth, and a. c. potentials raised by the cracks were measured at respective frequencies. The potentials had a linear relationship against the frequency and the gradient and intercept of the relationship depended on the number of cracks and crack depth. A new a. c. method was proposed for determining the number of cracks and crack depth by utilizing the frequency dependency of the gradient and intercept. The frequency dependency of the gradient and intercept from FEM analysis agreed with the experiment results qualitatively.
  • 河井 昌道, 益子 誉一
    2002 年 68 巻 672 号 p. 1228-1235
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    An extension of the macromechanical constitutive model to describe the viscoplastic behavior of unidirectional polymer-matrix composites is presented. A particular emphasis is placed on a more systematic incorporation of isotropic and kinematic hardening variables into modeling. Three-dimensional constitutive relatiops are derived from free energy and dissipation functions; these thermodynamic potentials are defined by using a transversely isotropic tensor of the fourth rank. The proposed model can be reduced to the existing macromechanical models for unidirectional composites as special cases. Consideration of the superposition of internal variables with different nonlinearities and introduction of the elastic region enhance the predictive capability of the proposed model. Nonlinear stress-strain behavior of a unidirectional carbon fiber-reinforced composite AS 4/PEEK under various off-axis loading conditions at different rates is simulated using the proposed model, and it is demonstrated that the model can favorably reproduce the rate-dependent off-axis nonlinear behavior of this composite system.
  • 瀧口 三千弘, 吉田 総仁
    2002 年 68 巻 672 号 p. 1236-1242
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    The present authors proposed a new technique of plastic bending of adhesively bonded sheet metals. In this process, large transverse shear deformation occurs in the adhesive layer, which in some cases would induce the geometrical imperfection (so-called 'gull-wing' bend) and the delamination. Since the strength of the adhesive is highly rate-sensitive, the amount of shear deformation of the adhesive layer and, as a result, 'gull-wing' bend, are strongly influenced by the forming speed. In the present work, the effect of forming speed on the deformation characteristics of adhesively bonded aluminum sheets was investigated by performing V-bending experiments with various punch speeds at room temperature. In order to discuss the effect quantitatively, the numerical simulations for the bending were also conducted using a rate-dependent constitutive model of plasticity for the adhesive. Consequently, it was found that the large shear deformation and 'gull-wing' bend are suppressed by high-speed forming since the deformation resistance becomes higher at high strain rate.
  • 桑水流 理, 吉川 暢宏
    2002 年 68 巻 672 号 p. 1243-1250
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    A new concept of pseudo-continuum model for plain-weave fabrics is proposed to analyze the complicated nonlinear behaviour under in-plane problems. The deformation of plain-weave fabric is categorized into three types in view of thread deformations, that is, skewing, straightening and extension. In this categorization, it is assumed that the bending and shear of threads caused by heterogeneousness or friction can be neglected. The skewing and straightening give rise to in-plane transverse compressive strain, and the extension means axial tensile strain. The warp and weft are individually subjected to these two strains with in-plane and anti-plane finite rotation. The geometrical nonlinearity, therefore, arises from the finite rotation of threads, while these strains are defined in the sense of infinitesimal strain. The framework of this pseudo-continuum model which consists of the equilibrium equation, the strain-displacement relationship and the constitutive law is newly constructed. The nonlinear behaviour under biaxial extension, that is a characteristic mechanical behaviour of the plain-weave fabric, is analyzed for the proof of validity of the proposed model.
  • 桑水流 理, 吉川 暢宏
    2002 年 68 巻 672 号 p. 1251-1258
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    A new breed of finite element is developed to analyze the nonlinear behaviour of plain-weave fabrics in the in-plane problems of arbitrary boundary condition. A nondimensional parameter called crimp parameter is introduced as an unknown to represent the crimp condition of warp and weft, and handled as a component of the displacement vector. The plain-weave fabric is homogenized by means of a newly defined strain-displacement relationship including the crimp parameter for the sake of consistent dealing with the three types of thread deformations, that is, skewing, straightening and extension. This homogenized model called pseudo-continuum model induces the geometrical nonlinearity with respect to the finite rotation of the threads, and its finite element is formulated by the principle of virtual work in the total Lagrangian description. The mechanism of nonlinear behaviour of the plain-weave fabrics is elucidated through several numerical examples by the proposed finite element.
  • 許 金泉, 武藤 睦治, 付 列東
    2002 年 68 巻 672 号 p. 1259-1265
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    The theoretical solution of a concentrated force on the free surface of a coating material is deduced by introducing the infinite series mirror points of the load point and applying the Dirichlet's uniqueness theorem. In this study, the two dimensional solution is deduced in details by using the infinite series of the Goursat's stress function corresponding to every mirror point. It is found that the stress function corresponding to a higher order mirror point can be determined from that corresponding to a lower one, therefore, all the stress functions can be determined from that corresponding to the first order mirror point which is in fact the stress function for concentrated forces on the free surface of a semi-infinite body. It is also found that the contribution of the stress function to stress distribution decreases as the increasing of the corresponding order of the mirror point. It is confirmed that only the stress functions corresponding to the first several mirror points have an influence on the accuracy of theoretical solution. This theoretical solution can be expected to be very useful in evaluating the strength of coating materials or other surface modificated materials.
  • 許 金泉, 付 列東, 武藤 睦治
    2002 年 68 巻 672 号 p. 1266-1272
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    The three dimensional theoretical solution of a normal concentrated forces on the free surface of a coating material is deduced by introducing the infinite mirror points of the load point and applying the Dirichlet's uniqueness theorem. The deduction is based on the basic equations of the spatial axisymmetric problems. It is found that all the stress functions corresponding to the mirror points, which satisfy the continuous conditions at the interface and the free boundary conditions at the free surface, can be deduced from the fundamental solution of a concentrated normal force on the free surface of a semi-infinite homogeneous solid. It is also found that only the stress functions corresponding to the first few mirror points have an influence on the accuracy of the theoretical solution. It is also found that the effect of material combination cannot be expressed by Dunders' parameters only. The stress field can be described by using Dunders' parameters together with the additional parameter.
  • 多田 幸正, 小田 康正
    2002 年 68 巻 672 号 p. 1273-1278
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this paper, an adaptive truss structure is an object of design. As in the problem of determining optimum posture for adaptive trusses there are many elements which must be treated simultaneously, it is difficult to obtain the global optimum solution due to the existence of many local optimum solutions. Then, we propose to use Immune Algorithms (IA) which is superior in the global convergence for solving problems with many local optima.
  • 小川 博文, 金子 新二, 鈴木 清輝, 坂 真澄
    2002 年 68 巻 672 号 p. 1279-1284
    発行日: 2002/08/25
    公開日: 2008/02/21
    ジャーナル フリー
    The effect of sputtering gas (Ar gas) pressure on the growth and the structure of Ti thin film membranes of 0.3-0.4μm thickness, microfabricated by magnetron sputtering, has been studied by transmission electron microscopy. In the present investigation, sputtering gas pressure was varied from 0.2 Pa to 2.0 Pa. The as-deposited Ti films showed very fine structures. The Ti films deposited at 0.2-1.1 Pa had hcp structures with preferred orientation. On the other hand, the Ti films deposited at 2.0 Pa appear to be a mixture of a random hcp structure and a cubic structure. The Ti films deposited at lower Ar gas pressures had dense structures with smooth flat surfaces, however, the rough surfaces of Ti films were promoted by elevated Ar gas pressures. Shadowing played a very important role in the coating growth of the Ti films. The lower tensile strength values of Ti films deposited at higher Ar gas pressures can be explained in terms of shadowing.
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