日本機械学会論文集A編
Online ISSN : 1884-8338
ISSN-L : 1884-8338
79 巻, 807 号
選択された号の論文の12件中1~12を表示しています
材料力学,機械材料など
一般論文
  • 中島 富男
    2013 年 79 巻 807 号 p. 1555-1570
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    A self-temperature compensating strain-measurement technique is proposed using a single fiber Bragg grating (FBG) sensor for a cyclic loaded testing-object heated moderately by itself. The technique adopts a moving-averaging method using the forward and backward Bragg wavelength data from an FBG sensor. One case was considered: a sinusoidal strain-change and a linear-functional temperature-change are assumed. In the case, it was derived that the self-temperature compensating strain-measurement is possible. The technique was applied to a test result, which is a strain-measurement result of a rotating aluminum-beam using an FBG sensor. The attempt was significantly successful. The self-compensated maximum and minimum strains were kept almost same values for about 1 hour, although the non-compensated strain s shifted to the tensile strain side as testing-time. These results indicate that FBG sensors are appropriate for applying to measuring dynamic phenomena than for applying to measuring quasi-static phenomena. The self-temperature compensating technique will be applicable to fatigue testing of metal materials, strain-measurements in vibration-tests, and strain measurements of rotating mechanical elements in machineries.
  • 小澤 則彦, 吉澤 智明, 渡辺 豊, 庄子 哲雄
    2013 年 79 巻 807 号 p. 1571-1580
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    In this research, a technique has been developed for quantitatively evaluating the magnitude of tensile and compressive residual stresses that is based on the surface strain measurements in the indentation process of the spherical indenter with the finite element method. When the spherical indentation is applied to the top surface of a steel plate, the elastic strain at an optimized position near the indentation is measured by strain gauges, where the residual stress and applied indentation stress are superimposed. In order to analyze the residual stress, FEM analysis has been conducted to establish the relationship between the elastic strain adjacent to the indentation and the indentation load for steel plates that are subjected to various tensile and compressive stress in the uniform residual stress and bending residual stress. A strain energy U* has been newly introduced. U* expresses the integrating along the trajectory about between the indentation load and elastic strain in a range from zero to the optimum load. U* is decreasing when the residual stress is at tensile state and it behavior has been verified by indentation test and finite element method. The application of this technique could contribute to the improved reliability of steel parts.
  • 赤井 淳嗣, 塩澤 大輝, 阪上 隆英
    2013 年 79 巻 807 号 p. 1581-1592
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    In recent years, fatigue limit estimation based on dissipated energy is getting an increasing attention in various industries because of its time and cost effectiveness. Heat treatment is applied to the material and machine components for the improvement of the mechanical properties. In this study, fatigue limit estimation based on dissipated energy measurement was applied to the evaluation of heat treated materials. Fatigue limit estimation by energy dissipation and conventional fatigue tests were conducted for as-received materials and re-solution heat treated materials of JIS type 304 steel to investigate the influence of grain size and the change of mechanical properties on energy dissipation. It was found from the fatigue limit estimation by energy dissipation that the fatigue limit of the re-solution heat treated materials could be precisely estimated, although estimated fatigue limit of the as-received materials obtained by energy dissipation was conservative values compared with that obtained by conventional fatigue tests. In conventional fatigue tests, volume fraction of martensite and its changing rate in the re-solution heat treated materials are less than those in the as-received materials. Therefore, the influence of the phase transformation to the re-solution heat treated materials was smaller than that to the as-received materials. The relationship between the dissipated energy and the plastic strain energy was also investigated. The dissipated energy in both materials could plot in the same straight line against plastic strain energy. The results in type 316L also plotted in the same line. It was found that materials with the same thermal property has same relationship between dissipated energy and plastic strain, even though mechanical properties of material are different from each other; thus the energy dissipation has a close relationship with plastic deformation.
  • 西籔 和明, 田邉 大貴, 鹿子 泰宏, 田中 茂雄
    2013 年 79 巻 807 号 p. 1593-1603
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    This study aims to reveal the behavior of debinding and sintering in metal powder injection molding (MIM) process using copper powders with varied particle sizes. The feedstock composed of micron- and submicron-sized copper powders and polyacetal-based binder was adequately prepared. Oxidation process was added between debinding and sintering steps for decarburizing. The effects of processing temperature in debinding, oxidation and sintering were evaluated from the changes in weight, dimension, and residual carbon and oxygen contents in addition to microstructure. From the results obtained using micron- and submicron-sized copper powders, it was clarified that the oxidation conditions was very important for stably-obtaining the high dense sintered parts with lower carbon and oxidation contents. This is considered to be due to the mechanism that the binder was removed from green compacts at 873K in vacuum, and then copper oxide whiskers form on the surface of copper powder and grow to connect the particles each other by oxidizing in air. The experimental result showed that using submicron-sized powder could obtain the sufficient high dense sintered parts under low sintering temperature (973K).
  • 原 英之, 志澤 一之
    2013 年 79 巻 807 号 p. 1604-1619
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    The fracture of ductile polymers occurs on a boundary between the molecular chain-oriented region and the non-oriented region after the neck propagation. This behavior is caused by the concentration of craze that is a microscopic damage typically observed in polymers. In this paper, the craze evolution behavior is decomposed into the nucleation and the growth of craze. A craze evolution equation is newly developed on the basis of chemical kinetics introducing strain rate and stain dependencies into an activation energy. Furthermore, in order to reflect the damage effect to the constitutive equation of molecular chain plasticity model, damaged and pseudo-undamaged configurations are defined. Then, using a multiscale material model homogenizing mixed structure of the glassy phase expressed by the molecular chain plasticity model and the crystalline phase represented by the usual crystal plasticity model in an unit cell, a FE simulation coupling with the craze evolution equation is carried out for a crystalline polymer subjected to the uniaxial load. It is attempted to computationally reproduce characteristic behaviors of craze evolution, i.e., the propagation of craze concentration region with the neck propagation in macroscopic specimen, the cessation of increase of craze in the molecular chain-oriented region and the craze nucleation before the macroscopic yielding.
  • 林 義一郎, 曙 紘之, 加藤 昌彦, 菅田 淳
    2013 年 79 巻 807 号 p. 1620-1631
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    In hydraulic turbine runners, accidents due to cyclic loading often occur. In this study, bending fatigue tests were carried out for the stainless cast steel SCS5 cut out from the hydraulic turbine runner vane used for 22 years, in order to clarify fatigue properties and fracture mechanism of SCS5 with artificial cavitation eroded surface. The test results are summarized as follows : (1)The fatigue strength of the specimen with artificial shallow cavitation eroded surface was higher than the specimen data cut out from vane inside. In the meanwhile, hole shape and uniformity part of artificial cavitation eroded surface was smaller than the specimen data cut out from that. (2)From SEM observation of the fracture surfaces, crack initiation sites were found to be the cavitation eroded surface and the casting defect which consist of dendritic phase and pore. (3)It is possible to evaluate the fatigue life of cavitation eroded hole shape by using stress concentration factor. (4)It is possible to evaluate the fatigue life of aged SCS5 by using the defect size √area and the initial stress intensity factor calculated by cavitation damage size and casting defect size. The value of the threshold stress intensity factor of cavitation eroded surface obtained in this study were 5.3 MPa·m1/2.
  • 髙井 直樹, 元木 信弥, 山崎 友裕
    2013 年 79 巻 807 号 p. 1632-1647
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    The effects of applied stresses on dynamic characteristics of piezoelectric ceramics are analyzed based on the nonlinear electroelastic theory. Piezoelectric ceramics are used in many electric devices as functional elements, where mechanical constraint is usually applied. Estimation of piezoelectric properties under applied stresses is important in designing the devices. However, applied stresses cannot be considered in the basic equations in the linear piezoelectric theory, and the effects of the applied stresses cannot be predicted. In this study, we introduce additional terms related to the dissipation effects, specifically, electric conduction and internal viscosity resistance, and nonlinearity of elastic properties into electroelastic theory. As well, considered nonlinear effects are elastic, piezoelectric and dielectric constants up to 3rd order. Frequency dependence of admittance of PZT disks is measured under applied compressions, showing that applied stresses have certain influences on either of thickness and radial vibrations of PZT. Assuming proper material constants, experimental results can be well explained by the nonlinear electroelastic theory.
  • 林 山, 福冨 広幸
    2013 年 79 巻 807 号 p. 1648-1656
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    It is time-consuming to inspect long pipes in power generation facilities using conventional ultrasonic testing techniques because scanning is necessary. Ultrasonic guided waves potentially provide an attractive solution to this problem because they can propagate several meters once they are excited at one location on the structure. This paper addresses the propagation of high frequency guided wave in a plate and in a pipe, and its interaction with localized wall-thinning on internal surface due to corrosion or erosion. Guided waves were generated in a stainless steel plate and a carbon steel pipe with thickness of 10mm, respectively. The pipe whose diameter is 318 mm contains artificial concave defects with different sizes in order to simulate localized wall-thinning on internal surface. A 2D finite element model was used to simulate wave propagation within the plate, and the characteristics of guided waves were also studied using a 2 MHz conventional transducer. The high frequency guided waves were explored for their capability of detecting and sizing defects.
  • 高橋 邦弘, 大宮 正毅, 磯 智之, 材木 裕, 櫻井 俊彰, 槇 徹雄, 漆山 雄太, 内藤 正志
    2013 年 79 巻 807 号 p. 1657-1668
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    To satisfy the requirements of high stiffness and lightweight structures, it is necessary to imagine the figure of an entire structure from the viewpoint of load transfer. A parameter Ustar (U*), which is independent of stress and strain, has been introduced by the authors for expressing load transfer under static loading. In the present study, we extend the definition of U* to dynamic loading. Three points: a loading point A, a support point B, and an arbitrary point C are the representative points in a structure for the conventional definition of U*. We introduced additional points D1, D2, D3,... for the expression of inertial forces under dynamic loading. New internal stiffness tensors are introduced to account for the effect of inertial forces. We find that a new internal stiffness can be expressed by the conventional internal stiffness, which implies that the high-speed computational algorism of the conventional U* is still applicable. Although the present method is intended to be applied to vehicle bodies under collision, the simple case for the plate is calculated here to verify the effectiveness of the method.
技術論文
  • 釜谷 昌幸
    2013 年 79 巻 807 号 p. 1669-1684
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    This study was aimed at deriving load multiplier (Z-factor) equations to assess the failure load of cracked pipes of class 2 or 3 according to the elastic-plastic fracture mechanics assessment procedure prescribed in the JSME Rules on Fitness-for-Service for Nuclear Power Plants (Codes for Nuclear Power Generation Facilities). The straight pipes with a circumferential surface crack under bending load and those with an axial surface crack subjected to internal pressure were analyzed. First, in order to conduct elastic-plastic fracture mechanics assessments, J-integral values were calculated for a pipe of Rm/t = 30, where Rm is the mean radius and t is the thickness of the pipe. It was confirmed that the J-values obtained were accurate enough for deriving elastic-plastic failure load. Then, the elastic-plastic failure loads were derived for carbon steels SPTP410 and STPG370 for various pipe and crack geometries. It was shown that the Z-factor of pipes with a circumferential pipe increased as the crack depth and pipe diameter increased. The Z-factors were tended to be small for pipes with an axial crack than those for pipes with a circumferential crack because the stress on the cracked plane was larger for the circumferential crack under the same load. Finally, equations for deriving conservative Z-factor of the cracked pipe were obtained.
ノート
  • 伊藤 寛明, 荒井 政大, 木村 皇輝, 柴原 直幸
    2013 年 79 巻 807 号 p. 1685-1689
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    Some experiments for press molding of glass spherical lens and its numerical simulation were carried out using finite element method. The optimal molding condition of slow cooling time that gives appropriate transcription profile was examined experimentally. Moreover, in order to investigate the temperature and internal stress distributions, numerical simulation was carried out using general purpose finite element code. As a result of comparing experiments with numerical simulations, it was confirmed that the relationship between amount of shrink of spherical lens and slow cooling time estimated by FE simulation approximately agreed with experimental value. Furthermore, it was found out that the optimal slow cooling time was 300-600 s by FE analyses.
  • 黒田 雅利, 釜谷 昌幸, 森 貴之, 猪崎 貴晴
    2013 年 79 巻 807 号 p. 1690-1694
    発行日: 2013年
    公開日: 2013/11/25
    ジャーナル フリー
    In order to develop more sensitive EBSD parameters to detect fatigue damage in austenitic stainless steel used as key material for nuclear reactor components, the new EBSD parameter focused on grain boundaries, which was referred to as the averaged grain boundary local misorientation (BMave), has been proposed by modifying the existing EBSD parameter of the averaged local misorientation (Mave). The applicability of the new parameter BMave to the fatigue damage detection was discussed by comparing with the exiting parameter Mave. As a result, it was found that BMave was more sensitive parameter than Mave. Especially, BMave (Option 1), which was calculated using the crystal orientations at points just adjacent to grain boundaries, was the most effective parameter for the fatigue damage detection.
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