材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
46 巻 , 5 号
選択された号の論文の19件中1~19を表示しています
  • 小畠 克朗
    1997 年 46 巻 5 号 p. 457-463
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 池野 進, 久米 治, 寺山 清志, 松田 健二, 上谷 保裕
    1997 年 46 巻 5 号 p. 464-469
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    A habit plane of plate-like α phase with peculiar wavy shape in a Cu-43.2mass%Zn alloy was investigated by the observation of Scanning Electron Microscope (SEM) and measuring of SEM-Electron Channeling Pattern (SEM-ECP).
    The results obtained are summarized as follows.
    (1) α phase having a wavy shape cross-section was observed at low magnification. It became clear that the α phase has a “galvanized sheets” shape, with the use of observation technique of relief images of α phase by preferential etching of matrix.
    (2) The preferential growth direction of the α phase is parallel to ‹5 5 6› matrix direction and the mean deviation angle between a plane of α phase and {0 1 1} band of SEM-ECP at {0 0 1} matrix plane was about 7 degrees. A habit plane obtained from the both relations is nearly {1 5 5}.
    (3) When the α phase grows in the cross-sectional direction, the shape becomes round and it looked like a bar with smooth outline at low magnification. From the apparent feature of α phase, which differs from the real, the preferential growth direction and the habit plane of the bar nearly equal to ‹1 1 1› matrix direction and {1 1 2} matrix plane, respectively.
  • 北川 正義, 勝見 誠二, 若生 豊, 山本 孝, 木水 貢
    1997 年 46 巻 5 号 p. 470-474
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In the previous papers it was shown that the mechanical properties of spider threads taken from Nephila clavata called Jorougumo in Japan were excellent and thus the threads were expected to be one of the most useful materials in future, if produced in large quantities. In this paper, the analyses of composition and crystalline structure of dragline silk and the deformation behavior of dragline and capture thread were investigated. The results are as follows: (1) glycine and alanine are the most abundant amino acids and occupy about 70% of the total amino acids, (2) the crystalline structure is orthorhombic and the dimensions of the unit cell are about a=1nm, b=0.9nm and c=0.7nm, (3) the load-strain curve for the capture thread is J-shaped and its fracture strain is more than 200%, and (4) a wonderful mechanism for the capture thread named as “windlass system” is reconfirmed.
  • 長谷部 忠司, 芝原 顕, 今井田 豊
    1997 年 46 巻 5 号 p. 475-480
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper proposes an evolution equation of hardening for FCC crystals from the microscopic point of view. The dislocation interaction with forest is considered to be responsible for additional hardening, which is experimentally observed in nonproportional loading for FCC polycrystalline metals with low stacking fault energy. The proposed model is incorporated into the constitutive equation based on the rate-dependent crystalline plasticity theory, and is applied to both monotonic and cyclic nonproportional loadings. In the former case, compressive tests following pre-torsion are conducted on three FCC metals with different stacking fault energy and the material dependency on hardening behavior is compared with the analytical results. The simulated results in the latter case, on the other hand, are compared with the formerly reported experimental results. The variations of additional hardening with strain path as well as material are demonstrated to be successfully described by the proposed model. The transition of the hardning behavior found in the stair-step path is also simulated. Small additional hardening reported under a large number of stair-steps can be described by the present analysis, which results from small nonproportionality in plastic strain history.
  • 平島 健一, 柴田 善央, 壁谷 聡浩
    1997 年 46 巻 5 号 p. 481-486
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Time dependent behavior of viscoelastic medium with an circular or elliptic tunnel is investigated by use of the correspondence principle between elasticity and viscoelasticity. The closed-formed analytical solutions for stress and displacement are obtained for the cases of in-plane and out-of-plane problems under concentrated forces and dislocations. The viscoelastic behavior of the medium is adopted to be represented by typical rheology models such as Burgers or Standard model for deviatoric stress and Elastic model for volumetric stress. Several numerical examples are shown by graphical representations.
  • 加納 昌男, 平澤 征夫
    1997 年 46 巻 5 号 p. 487-494
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper presents an estimation method for the experienced maximum load and displacement response by small load increment. The proposed method is based on the correlation between the initial secant stiffness of a damaged column by small load increment and the equivalent secant stiffness of the maximum response experienced. Nine reinforced concrete square column specimens were tested under static reversed cyclic loading. The variables were the loading direction, the pitch of the confining steel and the magnitude of the small load increment. The test results indicated that the relationship between the secant stiffness under small load increment and the equivalent secant stiffness corresponding to the maximum experienced response was represented by a logarithmic function. Also, the relationship between the displacement caused by small load increment and the experienced maximum displacement of the damaged columns was expressed by an exponential function. From these test results the applicability of the proposed method was examined. However, further experimental and analytical studies are needed to obtain a more reliable estimation method.
  • 牧野 寛之, 町田 進, 吉成 仁志
    1997 年 46 巻 5 号 p. 495-499
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    It is generally believed that ΔKeff is the most appropriate parameter which controls the fatigue crack propagation rate. On the other hand, the difference of the crack closing load from the crack opening load or the difference of the re-tensile plastic zone's generated load (RPG Load) from the crack opening load was also pointed out. However, the accuracy of usual measurements seems to be not sufficient to discuss quantitatively the above mentioned difference, in other words, the superiority of one of the fatigue crack propagation parameters ΔKop, ΔKcl, and ΔKRP.
    Under this background, successful measurement of the change in strain near fatigue crack tip with high accuracy was made in our previous report, and in this paper, matured consideration on the fatigue crack propagation parameter on the basis of the experimental results was carried out. From dividing the loading and unloading processes into several characteristic areas on the basis of the tendency which the compliance and the change rate of compliance show, the following observations have been obtained as conclusions.
    (1) In the unloading process, it seems to be impossible to isolate the area corresponding to the creation of the re-compressive plastic zone and there is also doubt about using the stress intensity factor because of the influence of crack closing. So it seems to be rational to adopt the area in the loading process, corresponding to the creation of the re-tensile plastic zone, for the fatigue crack propagation parameter.
    (2) According to the experimental results, it is clear that the re-tensile plastic zone's generated point disagrees with the crack opening point.
    (3) From the facts described above (1) & (2), it may be concluded that ΔKRP, not ΔKop nor ΔKcl, is considered the most suitable parameter which controls the fatigue crack propagation.
  • 宮地 紀子, 阿部 康弘, 浅山 泰, 青砥 紀身, 鵜飼 重治
    1997 年 46 巻 5 号 p. 500-505
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to investigate the effects of neutron irradiation on the creep and tensile properties of stainless steels, post-irradiation tests were made on the specimens of FBR grade type 316 stainless steel (316FR) and type 304 stainless steel.
    The post-irradiation tensile tests showed that the fracture elongation of both 316FR and type 304 stainless steel decreased and the 0.2% proof strength incresed by irradiation. These phenomena are related to the point defect accumulation due to neutron irradiation.
    The post-irradiation creep test of 316FR demonstrated that the time to rupture decreased to between 1/3 and 1/5 of the unirradiated one, and this reduction is smaller than that of type 304 stainless steels under the same irradiation and test conditions. The creep property degradation of type 304 stainless steel due to the irradiation is caused by accumulation of helium bubbles at the grain boundaries. As for 316FR, it is considered that beyond the neutron exposure level of 0.3dpa a growth of phosphide caused a decrease in solution hardening and accumulation of helium bubbles at the grain boundaries. It is concluded that the reduction ratio of time to rupture for both 316FR and type 304 stainless steels after irradiation became larger than 1/30, which is the lower limit of the reduction ratio for the “Monju” FBR.
  • 荒井 正行, 緒方 隆志
    1997 年 46 巻 5 号 p. 506-511
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to evaluate the crack initiation life precisely in the stress concentration portion of high-temperature components in power plants, it is important to comprehend the microscopic damage process under localized stress distribution. In this study, fatigue and creep-fatigue tests with tensile hold time were conducted on SUS304 stainless steel specimens, having V shaped double-edge notch, by using a high-temperature fatigue testing machine combined with a scanning electron microscope (SEM). As the results, it was found that the microscopic damage under the fatigue condition progressed by the initiation and propagation of a single main crack due to the accumulation of slip bands caused by strain concentration in the limited region around the notch root. On the other hand, under the creep-fatigue condition, many microcracks initiated in grain boundaries around the root corresponding to the microstrain distribution with a smooth gradient from the notch root. The main crack at the root was formed by coalescence of those microcracks and propagated by coalesing with the microcracks distributing ahead of the microcrack.
  • 西野 精一, 塩沢 和章, 相川 泰範
    1997 年 46 巻 5 号 p. 512-517
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effect of microstructure on creep and creep-fatigue behavior at elevated temperature was studied in Ti-6Al-4V alloy having three different microstructures. The three types of microstructure were prepared with different heat treatment conditions; that is, equiaxed α structure, lenticular α structure and bimodal (mixed of equiaxed α and lenticular α) structure. Creep test was carried out under constant load condition at 773K in air. Creep-fatigue test was carried out under total strain controlled condition using trapezoidal wave form with the hold time of 2min and 10min at 773K in air. The following conclusions were obtained. (1) The creep rupture strength of equiaxed α structure was similar to that of lenticular α structure and was larger than that of bimodal structure. (2) The number of cycles to failure under creep-fatigue condition of lenticular α structure was smaller than those of other structures. (3) The effect of microstructure on crack propagation life was small as compared with crack initiation life under creep-fatigue condition. (4) The fracture mode of equiaxed α and bimodal structures was transgranular fracture under creep-fatigue condition. On the other hand, crack of lenticular α structure was initiated and propagated at the interface between α layer precipitated at grain boundary and lenticular α structure.
  • 宮下 幸雄, Thomas HANSSON, 武藤 睦治, 北 秀紀
    1997 年 46 巻 5 号 p. 518-525
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fatigue crack growth behavior of silicon nitride at room and high temperatures was investigated. Fatigue crack growth mechanism at high temperature and the effect of grain size on crack growth behavior were also discussed. Higher crack growth resistance of larger grain size material was observed both at room and high temperatures. Crack growth resistance was high in cyclic fatigue compared to static fatigue, while the cyclic loading accelerated crack growth rate at room temperature and resulted in lower crack growth resistance. High temperature fatigue cracks grow by the microcrack initiation and coalescence mechanism, which is similar to room temperature. Soften grain boundary glass phase at high temperature significantly influences fatigue crack growth resistance: the high shear deformation rate of soften glass phase induces high rheological resistance and consequently high crack growth resistance.
  • 小寺澤 啓司, 井上 尚三, 内田 仁, 小園 泰史, 鶴井 孝文
    1997 年 46 巻 5 号 p. 526-531
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Tensile tests under cathodic charging were carried out on sensitized Inconel 600 alloy poly crystals. The maximum sensitivity of hydrogen embrittlement (HE) was recognized on the specimen sensitized at 973K, and the specimen fractured with intercrystalline mode. The effect of cold working before the sensitized treatment was recognized in the sensitivity of HE and the morphology of fractured surface. When the prestrain increased, the sensitivity of HE was decreased and the fracture morphology changed from intercrystalline to transgarnular. On the single crystal specimen, no effect was recognized in both the sensitized temperature and the cold working before sensitization. Intercrystalline and transcrystalline cracks occurred on the surface of polycrystal specimen by hydrogen charging under no loading condition. Also, the cracks on the surface of single crystal specimen were produced along {001} planes hydrogen under the same condition.
  • 酒井 譲, 渡邊 泰之, 太田 健一郎, 神谷 信行, 森 賢也
    1997 年 46 巻 5 号 p. 532-538
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    By using an electrolytic method palladium (Pd) specimens were loaded with hydrogen to investigate the effect of cold work on the hydrogen absorption property of Pd. In the successive experiments, it was clarified that the hydrogen content in the specimen remained almost constant or very slightly decreased with increasing the rate of cold work, which was contrary to the results obtained in another metals as Fe or Al. This result was interpreted as the difference of hydrogen absorption sites in metals. In Pd, hydrogen can be effectively stored in the interstitial positions of a normal lattice, which occasionally gives a quite high concentration ratio as almost n(H)/n(Pd)=0.9-1.0, and lattice defects induced by cold work, which are considered as the main location of hydrogen absorption in Fe or Al, only play a subordinate role. The cold work gave damage to the normal lattice of Pd, which insignificantly contributed to the overall hydrogen absorption because the total cross sectional area of damaged lattice was relatively small.
  • 小林 昭, 荻原 慎二, 粕谷 聡, 石山 和義
    1997 年 46 巻 5 号 p. 539-543
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    CFRP (Carbon Fiber Reinforced Plastics) have been increasingly used aerospace structures because of their weight saving effect. They are used in the form of multidirectional laminates. It is well known that delamination easily occurs in the CFRP laminates under transverse low velocity impact loading, and that the compressive strength of CFRP laminates with delamination reduces substantially. Therefore, the CAI (compressive strength after impact) problem has been studied extensively. However, most previous studies focused on the relationship between the compressive strength and the delamination area. For the design of performance materials, it is important to understand the microscopic damage behavior. There is few study on the microscopic damage progress in plain weave CFRP laminates under transverse loading. In the present study, instrumented drop weight impact tests and static transverse loading tests are conducted on plain weave CFRP laminates, and microscopic damage onset and propagation are observed by an optical microscope and a scanning acorstic microscope. It is found that fiber bundle fracture is dominant in impact loading, and delamination is dominant in static loading.
  • 根本 圭一, 粕谷 平和
    1997 年 46 巻 5 号 p. 544-550
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper deals with the problem of dynamic stability of angle-ply laminated cylindrical shells subjected to static and periodic axial compressive loading. First, the axially symmetric motion of the shell under loading is determined. Subsequently, certain perturbations are superimposed on this motion, and their behavior in time is investigated. The symmetric state of motion of the shell is called stable if the perturbations remain bounded. The solutions for the prebuckling motion and the perturbated motion are obtained by the use of Galerkin's method. Stability regions are examined by utilizing Mathieu's equation. The inevitability of dynamically unstable behavior is proved analytically and the effects of various factors, such as fundamental natural frequency, vibrated amplitude and dynamic unstable mode, are clarified.
  • 斎藤 博之, 高井 健一, 高沢 寿佳, 山内 五郎
    1997 年 46 巻 5 号 p. 551-554
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    When snow or ice sticks to radio communication antennas, it sometimes causes signal transmission problems. In many cases, the degree to which snow or ice sticks to antennas is based on the degree of adhesion.
    Recently, several water repellent coatings have been developed to prevent such adhesive problems. In this paper, the snow adhesive property of these water repellent coatings was experimentally studied. The following results have been obtained.
    (1) Fallen snow adheres to FRP samples much more than water repellent coatings.
    (2) Fallen snow adheres to samples at +1.5°C much more than at -5°C.
    (3) Snow naturally falls off from the surface as a block when its weight reaches a certain value for both of FRP and water repellent coating.
    (4) The estimated value of snow falling off coincides with the experimental value.
  • 平野 貞三, 今井 康文, 林 佳彦
    1997 年 46 巻 5 号 p. 555-562
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Three-dimensional stress and strain analysis considering the effect of strain rate on polyester under uniaxial tension and torsion was investigated by the scattered-light method. The difference in principal strains on the symmetrical section in tension problems could be calculated using two kinds of scattered fringe patterns obtained by two different incidences of polarized light. The shearing strains on the symmetrical section in torsion problems could be calculated using scattered fringe patterns obtained by one directional incidence. Finally, a new method was proposed for the estimation of the equivalent shearing stress and strain, the deviatoric stresses and strains on the symmetrical section in a three-dimensional model under uniaxial tension from the measurement of only the fringe gradient and its rate of increase. The method could estimate the equivalent shearing stress and strain in the model under torsion, too. This method was applied to a visco-elasto-plastic problem of a cylindrical specimen with a semi-circular notch under uniaxial tension and torsion. The distributions of strain rate, strain and stress on the notched section were estimated. The results were consistent with those calculated using the finite element method.
  • 中山 昇, 福島 学, 安本 義正, 佐野 利男, 武石 洋征
    1997 年 46 巻 5 号 p. 563-567
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to study the propagation characteristics of stress pulses in various structures, the reflection wave reflected from a fillet part is measured. The part is made of same material as the structure. A semiconductor strain gauge is used for the detection of stress waves. The reflection coefficient is obtained as the summation of the transfer function. The reflection coefficient is calculated by changing the duration of stress pulse and the curvature of fillet. As the result, it becomes clear that the reflection coefficient can be obtained from strain energy without using Discrete Fourier Transform if a single pulse is used.
  • 北條 正樹, 影山 和郎
    1997 年 46 巻 5 号 p. 568-574
    発行日: 1997/05/15
    公開日: 2009/06/03
    ジャーナル フリー
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