日本機械学会論文集 A編
Online ISSN : 1884-8338
Print ISSN : 0387-5008
53 巻, 488 号
選択された号の論文の26件中1~26を表示しています
  • 白鳥 正樹
    1987 年 53 巻 488 号 p. 677-683
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
  • 関根 英樹, 下村 慶一, 濱名 則夫
    1987 年 53 巻 488 号 p. 684-692
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this paper is discussed the effect of water environment on the fracture toughness of glass chopped strand reinforced plastics. Fracture toughness tests were performed by using compact tension specimens of the composite immersed in distilled water for 10 days to 1.5 years, and acoustic emission signals were detected during the tests. The observation of fractured surfaces by a SEM and the quantitative analysis of dissolution elements from glass fibers by an atomic absorption spectrophotometer were also carried out to clarify the degradation mechanism of the composite. As the result, it was found that (1) the fracture toughness obtained by acoustic emission method decreases as the immersion time is longer : (2) the decrease of the fracture toughness is caused by the degradation of the bonding interface between glass fibers and resin matrix and the weakening of glass fibers due to the dissolution of the elements into the water.
  • 守屋 一政, 市川 武彦
    1987 年 53 巻 488 号 p. 693-696
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    Edge delamination is one of the major factors that determine the fatigue strength of composite laminates and it is attributed to the existence of highly intensified interlaminar stresses in the neighborhood of the free edge. In order to develop an efficient method to prevent edge delamination, in this paper, the effects of the geometrical shape of the free edge on rσ stress singularity are discussed for cross-ply laminates. It is shown that the order to stress singularity can be controlled by varying the geometrical shape of the free edge and that the singularity disappears for some combinations of the angles which the edge surfaces of the two neighboring layers make with respect to their interface. In the case of multi-layer laminates, it is also possible to eliminate stress singularity completely or to reduce its order drastically at all interfaces by slanting the entire free edge at an appropriate angle.
  • 祖父江 靖, 小河 昭紀, 森 久
    1987 年 53 巻 488 号 p. 697-701
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    The acoustic Emission Characteristics are investigated for various failure modes (such as fibre breakage, matrix crazing and delamination) of Boron reinforced Aluminum Composites materials. Tensile Tests are conducted for specimens of four kinds of type (unidirectional, 0°/90° ply, boron fibre and shear lag test pieces). The results show that A. E. Characteristics (count rate, amplitude distribution and location) are different with failure modes. A. E. amplitude is above 90 dB for the fibre breakage of unidirectional ply test piece but below 90 dB for the transverse one of cross ply, which fractured at low level load, while the shear lag test pieces produce acoustic emission amplitude in the range of 40∼60 dB under delamination fracture mode.
  • 小峰 厚友, 山口 徹, 菊池 雅男, 木林 靖忠
    1987 年 53 巻 488 号 p. 702-708
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    The effect of surface working (shot peening) and additional post working heat treatment on the fatigue properties of carburized steel with surface structure anomalies was evaluated through rotating bending fatigue tests. Smooth specimens with various surface roughness and notched specimens were gas carburized and shot peened. Some smooth specimens were tempered after shot peening to examine the effect of post working heat treatment. Hardness, residual stress and the amount of retained austenite near the surface of the carburized and shot peened specimens were measured. The fatigue strength of all of the shot peened specimens increased and was as much as 90% higher than that of carburized specimens. The smooth specimen tempered at 100°C after shot peening gave the highest fatigue strength among all samples tested in this study.
  • 田中 啓介, 秋庭 義明
    1987 年 53 巻 488 号 p. 709-717
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    A method for predicting the fatigue thresholds of notched components proposed by Tanaka and Nakai was modified to obtain a simpler formulation. The method requires three material data for prediction : the fatigue limit of smooth specimens, the threshold stress intensity range for long cracks, and the threshold value of the effective stress intensity range. For notched components, the fatigue limit for crack initiation, the fatigue limit for fracture, and the length of non-propagating cracks are predictable as functions of the applied stress and notch geometry. The fatigue tests were conducted with center-notched plates of low-carbon steel with two different grain sizes and the results were compared with the prediction. Good agreement was obtained for the fatigue limit for the nucleation of a Stage II crack. The prediction was slightly conservative for the fatigue limit for fracture. Agreement in the length of non-propagating cracks between prediction and experiment was fairly good. Several simple formulae were derived for easy application for practical purposes.
  • 木村 雄二, 矢ケ崎 隆義, 国尾 武
    1987 年 53 巻 488 号 p. 718-723
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    The present authors have been investigated on the corrosion fatigue crack initiation process of a ferritic stainless steel. Consequently, it was indicated that corrosion pit formulation is important for the corrosion fatigue crack initiation of this material. The factor which governs the corrosion pit nucleation process, however, has not yet been clarified. Therefore, in this paper, the mechanisms of pit formulation in the corrosion fatigue crack initiation process were investigated from the microstructural and crystallographical points of view. As a result, it was made clear that, few corrosion pit generation was recognized in the grains which have preferable crystal orientation for operating multiple slip systems. Therefore, it is understood that the two-dimensional opening of the surface passive film, which is caused by multiple slip deformations, is necessary for corrosion pit generation.
  • 松岡 三郎, 湯山 道也, 西島 敏
    1987 年 53 巻 488 号 p. 724-731
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    Axial-and diametral-strain-controlled low-cycle fatigue tests were performed on carbon and low-alloy steels with both an axial and a diametral extensometer mounted on the same cylindrical specimen. The results obtained are summarized as follows. (1) Young's modulus, E, under cyclic plastic deformation was given by E=σal<ea>=σa/(εl<ta>-εl<ea>), where σa is stress amplitude, and εl<ea>, εl<ea> and εl<pa> are total, elastic and plastic strain amplitudes in the axial direction, respectively. E was nearly equal to 206 GPa when εl<pa>=0, while it decreased with increasing εl<pa>. (2) Poisson's ratio for elastic and plastic strain, υe=-(εd<ea>/εl<ea>) and υp=-(εd<pa>/εl<pa>), were nearly equal to 0.3 and 0.5, respectinely, where εd<ea> and εd<pa> are diametral elastic and plastic strain amplitudes. (3) Strain-fatigue life properties for axial and diametral strain-controlled tests were coincident each other when the axial strain was calculated from the measured diametral strain through an equation of tranformation on the assumption that E=206GPa, υe=0.3 and υp=0.5.
  • 岡安 啓好, 宮本 博, 町田 賢司, 川添 豪
    1987 年 53 巻 488 号 p. 732-739
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    The plastic zone created at the crack tip is observed microscopically by using a scanning electron microscope. CT specimens of 2017-T4 and 7075-T6 aluminum alloy are loaded to or over the JIC level and the crack tip regions are observed, so that size of the process zone (PZ) and the fracture mechanism in it are estimated. The results are as follows : (1) In the process zone, the number of nucleated voids and their diameters are decreased along the propagation direction of crack. The size of PZ is about 100∼130 μm for 2017-T4 and 50∼150 μm for 7075-T6. (2) The diameter of the void which is nucleated at the inclusion in the process zone, increased with the increase in J value and saturated just before separation, that is, at the nucleation of the dimple. (3) Coalescence of voids seems to occur in two ways. (4) For ductile fracture as in 2017-T4 and 7075-T6, the crack tip is always blunted both on the blunting line and the R-curve.
  • 幡中 憲治, 藤満 達朗, 白石 進
    1987 年 53 巻 488 号 p. 740-747
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    Low cycle fatigue tests were performed under load controlled conditions with tensile mean stress, and short surface crack growth was investigated in association with crack closure. The short crack growth rate was successfully analyzed in terms of the cyclic J integral range ΔJ and the strain intensity factor range ΔKε, which were estimated by disregarding the crack closure, in a practical sense. The detailed discussion, however, showed that crack closure should be taken into consideration in the estimation of ΔJ even for short cracks since an effective load ratio U is about 0.85 especially in the load controlled test with a load ratio of R=-1.0. The crack tip opening displacement range ΔΦt is a more important parameter for controlling short crack growth than ΔJ and ΔKε. It was noticed that the da/dN vs. ΔΦt plot of a short crack was situated on the higher side of da/dN, compared with that of a through-thickness center crack.
  • 幡中 憲治, 藤満 達朗, 市山 弘幸
    1987 年 53 巻 488 号 p. 748-754
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    JIN SNCM439, S35C and SUS304 steels were low cycle fatigued with mean stress and strain under load and displacement controlled conditions. The cyclic J integral range, ΔJ and the crack tip opening displacement range, ΔΦt(200) were not effective for evaluation of the crack growth rate under test conditions accompanied by a ratcheting deformation. Then, the parameter of ΔJ/{1-(Φcmincmax)}0.2, which can control the acceleration or the crack growth rate due to the ratcheting deformation as well as the crack growth rate under the fully reversed cyclic strain, was usefully proposed here, where Φcmin and Φcmax are minimum and maximum crack center opening displacements. The ΔΦt(200) was correlated with ΔJ by the equation of type of ΔΦt(200)=A(ΔJ)q. In general, the power exponents, q are smaller than the value of 1/(n'+1) or 1/(n+1) estimated by assuming the HRR singular field around the fatigue crack tip where n' and n are the cyclic and monotonic strain hardening exponents of materials.
  • 梅田 洋, 坂根 政男, 大南 正瑛
    1987 年 53 巻 488 号 p. 755-763
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper describes the accuracy of FEM analysis for the estimation of local strain at the notch root in creep-fatigue conditions, comparing the local strain calculated by FEM with the measured strain using high temperature strain gages. The specimens are commercial pure aluminum notched plates with both side grooves whose elastic stress concentration factors are 0.5 and 2.0. The test was made at 473 K in air. The following results are obtained. In no-hold time fatigue tents, FEM analysis accurately estimates the local strains at the notch root. In no-hold time fatigue tents, FEM analysis accurately estimates the local strains at the notch root. In the hold time test, on the other hand, FEM analysis estimates a smaller strain range compared with the actual strain range occurring at the notch root. The reason for the disagreement between FEM analysis and the actual strain results from the change in material response due to creep loading. In the creep-fatigue condition, so-called plastic-creep interaction, the FEM analysis does not take account of, occurs. The local strain calculated from conventional methods, Neuber's rule, Stowell-Hardrath-Ohman, Koe's methods are also compared with the strain measurement for no-hold time tents. All the methods overestimate the strain concentration at the notch root.
  • 猪狩 敏秀, 瀬戸口 克哉, 若松 良彦, 野村 真一
    1987 年 53 巻 488 号 p. 764-771
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    An experimental study of macroscopic creep behavior of perforated plates was performed to verify the prediction method proposed by the authors. Creep tests of perforated plates and flat plates made of Hastelloy X were carried out at 800°C and 950°C, and a comparison between the predicted minimum creep rate of perforated plates and the experimental results was made. Predicted results coincided well with experimental results, and an applicability of the prediction method, which contributes to the definition of the effective stress of perforated plates considering the effective section area, was clarified. Moreover, the possibility of predicting the macroscopic creep rupture properties of perforated plates was examined based on the effective stress together with the creep rupture properties of flat plates, and a good agreement was found between prediction and experiment.
  • 石川 博将, 村山 淳
    1987 年 53 巻 488 号 p. 772-778
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    The behaviour of a pure copper subject to conventional creep and cyclic creep under imposed load is examined at room temperature, 200°C, 300°C, and 400°C to show the relation between these two kinds of phenomena. Plots of observed strain, not against the number of cycles, but against time are available for the direct comparison between cyclic creep and creep. The plastic strain, of which the instantaneous strain consisted together with the elastic strain, has considerable effect on the succeeding mechanisms of both creep and cyclic creep. At a high temperature of 400°C, strain accumulation due to creep is much more than that due to cyclic creep, while at room temperature cyclic creep has the superiority.
  • 白鳥 正樹, 三好 俊郎, 酒井 義明, 張 光栄
    1987 年 53 巻 488 号 p. 779-785
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    An influence function method has been developed to analyze stress intensity factors, K, for surface cracks which are subjected to arbitrarily distributed surface stresses. The method has been applied to the analysis of a series of influence coefficients, how easily the K values for a semielliptical surface crack in a round bar can be evaluated against arbitrarily distributed surface stresses. Some examples have been provided to show the effectiveness of the proposed method, including the variation of K due to rotary bending of the round bar, distributions of K in a residual stress field, and those for the cracks existing at the notch root.
  • 渡辺 勝彦, 佐藤 裕
    1987 年 53 巻 488 号 p. 786-794
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    The discontinuous crack model is model in which the discontinuities around a crack tip are taking into consideration as the first-order approximation and which can be thought of as the most generalized model of the Dugdale's. In this paper, fundamental investigations are made to let this model be a match for usual continuum crack model in its generality and applicability. The contents are as follows : (1) A general method to give the constitutive equation for the plane considering a discontinuity that conforms to a continuum without any contradiction is shown by introducing a strain-like quantity. (2) Finite element formulation for the discontinuous plane is shown by using plane elements. (3) Finite element analyses of an elastic-plastic crack and an elastic-creep crack are carried out, and the applicability of the model is discussed through the evaluations of crack parameters.
  • 村上 澄男, 河井 昌道, 栄 輝
    1987 年 53 巻 488 号 p. 795-801
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    An anisotropic creep damage theory is implemented into the finite element analysis of the creep damage process in structural elements. The evolution equation of creep damage and the creep constitutive equation of damages materials were established by means of a second rank symmetric damage tensor Ω. The creep constitutive equation of McVetty type combined with a strain hardening hypothesis is assumed. The process of a plane creep crack growth in a thin plate with a circular hole at 250°C due to anisotropic creep damage under proportional and non-proportional loadings is analysed by this method. The effect of damage anisotropy on the creep crack extention and the final rupture time is discussed in contrast with the corresponding numerical results based on an isotropic damage theory.
  • 岸田 路也, 佐々木 一彰, 石井 悟
    1987 年 53 巻 488 号 p. 802-808
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper describes a stress concentration problem of circular bar with annular groove under axisymmetric torsion in the linear couple-stress theory. For this analysis, the indirect fictitious-boundary integral method is used. As a result, the influence of parameters, such as the characteristic length and the ratio of bending-twisting moduli, on stress concentration factors is made clear.
  • 間島 保, 尾形 也寸夫, 中澤 一
    1987 年 53 巻 488 号 p. 809-815
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    Notch tensile tests are carried out to evaluate the effects of stress triaxiality at the net section and uniaxial tensile properties on the notch tensile strength. Notched specimens with U-shaped circumferential notches of three different notch radii and three different notch depths are employed. These specimens are made of four kinds of ductile materials chosen so that the difference in ductility may be wide. The notch strength ratio increases with the stress triaxiality factor proportional to the ratio of hydrostatic to equivalent stress, and with the ratio of local to total elongation in engineering stress-strain curves obtained from uniaxial tension tests. The notch strength ratio is determined by the multiplication effect of these two factors. The value of the notch strength ratio can be predicted by the experimental equation composed of the product of the ratio of local to total elongation and the stress triaxiality factor. Notch strengthening is caused by the above two primary factors.
  • 長谷川 久夫
    1987 年 53 巻 488 号 p. 816-819
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper is concerned with the methods of solution, in terms of strain functions and complex stress functions, for two dimensional problems of elasticity. The principal results are as follows : (1) The method of solution in terms of complex stress functions, which are related to Airy's stress functions, can be obtained as a special case from the methods of solution in terms of strain functions such as the so-called Galerkin type and Papkovich-Neuber type strain functions. (2) The relations between complex stress functions, Papkovich-Neuber type strain functions and Galerkin type strain functions are shown. (3) Any one of the three strain functions in Papkovich-Neuber strain functions may be dropped without loss of generality, under the conditions that the body forces are absent. (4) The so-called Papkovich-Neuber type strain functions for problems with body forces under plane stress conditions are shown.
  • 野口 博司, 西谷 弘信, 後藤 浩文, 森 和也
    1987 年 53 巻 488 号 p. 820-826
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    The semi-infinite bodies with a semi-ellipsoidal pit under uni-axial tension were analyzed by the body force method. The fundamental solutions necessary for analysis of the semi-infinite body under uni-axial tension were given newly in this paper. In numerical results, the effects of the free surface in the semi-infinite body were discussed by comparison with the infinite body with an ellipsoidal cavity.
  • 神谷 豊, 高橋 賞, 牧 充, 細江 哲
    1987 年 53 巻 488 号 p. 827-833
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    While many geometrical studies on the hourglass worm gear have been reported, there are few studies on its intensity. In this paper the root stress distribution in the direction of the tooth trace and the stress distribution in the direction of the tooth depth are measured by the three-dimensional photoelastic method, when a pair of classical hindley worm gear are loaded statically. The results indicate that maximum tensile stress is generated on the root of the tooth which is located at 60 degrees to 70 degrees from the contact markings along the worm tooth trace.
  • 中川 博文, 高橋 賞
    1987 年 53 巻 488 号 p. 834-842
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    It the first report, we described a new contact pressure measuring method. Using this, it is possible to measure at once both the direction and magnitude of the contact pressure between the feet and the floor surface from a circular isochromatic pattern. We derived the relative equations for determining direction and magnitude on the basis of experimental data to make automatic analyses by computers in the near future. In this study, using this method we attempted to analyze the walking of both normal children and those affected by Down's syndrome.
  • 松原 雅昭, 岡村 弘之
    1987 年 53 巻 488 号 p. 843-847
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    Present paper proposes a new algorithm of the integrity evaluation of the pressure vessel of nuclear reactors pressurized thermal shock, PTS. This method enables us to do an effective evaluation by superimposing proposed "PTS state-transient curves" and "toughness transient curves", and is superimposing proposed "PTS state-transient curves" and "toughness transient curves", and is superior to a conventional one in the following points ; (1) easy to get an overall view of the result of PTS event for the variations of several parameters, (2) possible to evaluate a safety margin for irradiation embrittlement, and (3) enable to construct an Expert-friendly evaluation system. In addition, the paper shows that we can execute a safety assurance test by using a flat plate model with the same thickness as that of real plant.
  • 小森 和武, 加藤 和典, 室田 忠雄
    1987 年 53 巻 488 号 p. 848-855
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    In the field of bar rolling, there is little theoretical research, because the flow of material in bar rolling is complicated. Recently, we proposed a new energy method using finite element division, and this method was applied to the analysis of the flow of material in two types of bar rolling : square-diamond pass and round-oval pass. Howeve there is still an important type of bar rolling : square-oval pass. In this type, the side region of the material is reduced earlier than the other part, whereas the central region of the material is reduced earlier in the former two types. So the flow of material in this type differs a lot from that of freedom of velocity fields must be increased for precise simulation of the flow of material. In this paper, we have improves the method to lessen computation time and memory requirements. Then, this method is applied to the analysis of material flow in square-oval pass, and reasonable results are obtained for rolling properties such as width spread, strain rate distribution, folding of stress-free side surface, etc.
  • 高橋 賞, 末次 正寛, 島本 聡
    1987 年 53 巻 488 号 p. 856-860
    発行日: 1987/04/25
    公開日: 2008/02/21
    ジャーナル フリー
    It is difficult to solve the problem of stress-strain distribution in plastic regions in comparison with elastic bodies. Thus, an attempt to expand and apply stress- strain analysis by photoelasticity, with regard to polycarbonate resin in plastic photoelasticity, has been promoted so far and many significant achievements have resulted therefrom. This study is an examination of the possibilities of the plastic strain freezing method in comparison with the elastic stress freezing method. First, we attempted to determine the best temperature for plastic strain freezing. Further, it became apparent from systematic experimental results that it is 'strain' and not 'strain' which is frozen in plastic regions. In other words, it was made clear that the Birefringence N in strain freezing was proportional to difference in the principal strains (ε12).
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