日本機械学会論文集 A編
Online ISSN : 1884-8338
Print ISSN : 0387-5008
58 巻, 547 号
選択された号の論文の26件中1~26を表示しています
  • 塩沢 和章, 水谷 淳之介, 西野 精一, 江幡 節男, 横井 信安, 春山 義夫
    1992 年 58 巻 547 号 p. 341-347
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    Corrosion fatigue crack propagation tests of squeeze-cast Al-Si aluminum alloy, AC 8 A-T 6, were performed under the conditions of the stress ratio of 0.1, triangular waveform and testing frequency, f, of 0.1, 1 and 5 Hz in 3.0% saline solution using compact tension specimens with side grooves. The experimental results obtained in this investigation were compared with those reported previously under the tests of f=10Hz. Corrosion fatigue crack propagation behavior under f=0.1 and 1 Hz was also affected by the initial stress intensity factor range, ΔKi, as the test was started, the same as that under f=10 Hz. It was observed that the retardation and complete arrest of crack propagation occur within a short period in low ΔK, due to the wedge effect induced by the corrosion products. This behavior was explained uniquely by the contributory stress intensity factor range, ΔKcont, considering the viscoelasticity of the corrosion products formed within a crack. The enhancement in da/dN occurred immediately after starting the test because the preferential dissolution around the eutectic spheroidal silicon was not dependent on ΔKi, or f. Corrosion fatigue cracks were apt to propagate along eutectic spheroidal silicon, as compared with that in air, and this behavior was independent of f.
  • 後藤 真宏, 前畑 俊之, 西谷 弘信, 宮川 浩臣
    1992 年 58 巻 547 号 p. 348-352
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    In order to clarify the small-crack growth behavior in oil environments, rotating bending fatigue tests of annealed 0.34 % C steel plain specimens with a small blind hole are carried out in environments of paraffinic base oils having 4 viscosities η. The cycle frequencies f used are 12.5, 25 and 50Hz. The main results obtained are as follows : the effect of oil viscosity η on the growth rate of a small crack dl/dN depends on the cycle frequency. The relation between the crack propagation life and the term ηf is approximated by a smooth curve. The maximum propagation life appears at around ηf=2×10-3 m2/s2. The existence of ηf which prodce the maximum propagation life seems to generate the dissimilar effect of η on dl/dN under the different values of f. dl/dN of a small crack is determined uniquely by the term σnal
  • 越智 保雄, 石井 明, 佐々木 茂美, 小西 康哉
    1992 年 58 巻 547 号 p. 353-358
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    Rotating bending fatigue tests were carried out on mainly pearlitic spheroidal graphite cast iron (pearlitic ductile iron, PDI) of smooth specimens at room temperature. Initiation and propagation behavior of surface microcracks was discussed by means of detailed successive observations of the surface and the fracture surface. The results were compared with the results of ferritic spheroidal graphite cast iron (FDI) which had been reported by the authors. The surface crack initiation was governed mainly by microshrinkages existing just under the surface in both PDI and FDI materials. A low level of negative correlation between the crack initiation life Ni and the maximum stress intensity factor of defect front KImax by evaluating from the area of microshrinkage as the crack initiation site was found in both PDI and FDI, but the values and the variation of KImax in PDI were larger than those in FDI. Surface cracks propagated with the branching and the coalescence during the fatigue process, but the crack propagating path in the pearlite base was comparatively more linear than that of the ferrite base in FDI. It was found to exhibit a decrease in the crack propagation rate da/dN during the range of small cracks in the low stress level ; on the other hand, in the high stress level the da/dN was found to be a remarkable repetition of increase and decrease in the small crack region. This behavior of the da/dN in the small crack region was similar in both PDI and FDI.
  • 中井 善一, 近藤 勝彦, 大路 清嗣
    1992 年 58 巻 547 号 p. 359-366
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    The short surface fatigue crack growth behavior of a high-strength aluminum alloy, 7075-T651, was examined in deaerated aqueous 3.5% NaCl. The growth rate of long cracks in corrosion fatigue was almost the same as the rate in air when the stress intensity range was smaller than 7 MPa√(m). In this region, the growth rate of short surface cracks was higher than that of long cracks in the same environment. Since the da/dN-ΔK relation of short surface cracks in air was located between the da/dN-ΔK relation and da/dN-ΔKeff relation of long cracks, the difference in crack closure may be responsible for the acceleration of short crack growth in air. Since the da/dN-ΔK relation of short surface cracks in corrosion fatigue was located left of the da/dN-ΔKeff relation of long cracks, and the value of ΔK is always greater than ΔKeff, the acceleration of short surface crack growth in corrosion fatigue cannot be explained solely by the difference in crack closure. The observations of fracture surface by scanning electron microscopy showed that the difference in the crack growth mode was also responsible for the acceleration.
  • 伊藤 高敏, 林 一夫
    1992 年 58 巻 547 号 p. 367-371
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    Closure process of a transverse crack crossing a wellbore is analyzed to discuss physical meanings of the pressure decay curve after shut-in during hydraulic fracturing tectonic stress measurements, where the crack is assumed to be perpendicular to the wellbore axis and one of the principal axes of the tectonic stress is assumed to be parallel to the wellbore axis. The analysis is based on the linear theory of elasticity and linear fracture mechanics. It is shown that the whole crack closes instantaneously when the downhole water pressure is equal to the compressive tectonic stress acting perpendicularly to the crack plane. The instantaneous crack closure appears as a point of maximum curvature on the pressure decay curve after shut-in. Therefore, the compressive tectonic stress normal to the crack plane is determined as the pressure at the point of maximum curvature. Although the point of maximum curvature appears less clearly on pressure decay curve when the fluid loss coefficient is large, the instantaneous crack closure can always be detected clearly by utilizing the relation of the inverse of the decrease rate of the downhill water pressure Vs the downhill pressure.
  • 陳 玳〓, 西谷 弘信
    1992 年 58 巻 547 号 p. 372-378
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this paper, the characteristics of the stress and displacement fields for two bonded half planes containing an arbitrarily oriented semi-infinite crack meeting the interface are studied as a plane problem. The eigenequation, by which the order of stress singularity is determined, is given in an explicit closed form. A uniform expression is presented for the stress distribution near the crack tip. The intensity of the singular stress field is generally defined in terms of two real constants.
  • 秋山 孝夫, 鈴木 一義, 原 利昭, 渋谷 寿一, 小泉 尭
    1992 年 58 巻 547 号 p. 379-385
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper deals with the axisymmetric torsion problem of an infinite hollow cylinder with a pair of external and internal circumferential cracks located on an even plane. The problem is reduced to the solution of an infinite system of simultaneous equations in which the stress on the plane is expressed as an appropriate Fourier series. Numerical results are obtained for the stresses around the crack tips and stress intensity factors.
  • 五嶋 孝仁
    1992 年 58 巻 547 号 p. 386-392
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper deals with two-dimensional rolling-sliding contact problem on an elastic half-space containing multiple growing surface cracks located close to each other. Rolling-sliding contact is simulated as Hertzian-distributed contact load with normal and shear components. The problem is solved using complex-variable techniques and is reduced to multiple singular integral equations which are solved numerically. Numerical results of stress intensity factors are obtained for the case of two parallel cracks. The interference effects on the stress intensity factors with the distance between two cracks, and the effects of the frictional coefficient, crack angle and crack length on the results are considered.
  • 五嶋 孝仁, 宮尾 嘉寿
    1992 年 58 巻 547 号 p. 393-399
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    This paper deals with the two-dimensional rolling-sliding contact problem with transient heat generation on an elastic half space containing a surface crack. Rolling-sliding contact is simulated as an arbitrary distributed contact load with normal and shear components, moving with constant velocity over the surface of the half space. The transient heat generation on the contact region is supposed to vary as the step-function of time. Numerical results are given for the cases of Hertzian and parabolic distributed loading and heating, respectively. It is considered hot the slide/roll ratio, Peclet number, the crack angle and the heat transfer coefficient on the crack face affect he stress intensity factors.
  • 村上 竜一, 西岡 俊久, 松尾 諭, 橘高 弘幸
    1992 年 58 巻 547 号 p. 400-407
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    The optical method of caustics is one of the most powerful techniques for evaluating stress intensity factors in static as well as dynamic fracture mechanics problems. In the method of transmitted caustics, optically anisotropic (birefringent) materials such as Araldite B and polycarbonate were often used. Double caustic curves appear for a tip of the crack in an anisotropic (birefringent) plate, due to the birefringence. In this paper, a caustic theory was developed for stationary cracks in birefrigent materials under in-plane mixed-mode conditions. Completely analytical expressions were derived for the double caustic curves as well as for the double initial curves. The combined effects of optical anisotropy and mixed-mode state on the caustic curves and the initial curves were investigated. New procedures were also developed for the evaluation of mixed-mode stress intensity factors using the characteristic dimensions of the double caustic patterns.
  • 森 和也, 陳 玳〓, 西谷 弘信
    1992 年 58 巻 547 号 p. 408-411
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    Ceramics are brittle materials. Therefore, it is important to evaluate the fracture toughness of them. Mendiratta et al. proposed the Indentation-Induced Flaw method to evaluate the fracture toughness of ceramic materials. This method is simple and useful. However, the values of stress intensity factor for a semi-elliptical surface crack in the specimens under three-or four-point bending are necessary to obtain the fracture toughness. We calculate the accurate stress intensity factors for JIS ceramic bending specimens with a semi-elliptical surface crack under three-or four-point bending. The approximate expressions for the stress intensity factors are also given.
  • 嘉納 豊, 阿部 博之
    1992 年 58 巻 547 号 p. 412-419
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    A new procedure is proposed to evaluate the 3D crack shape nondestructively with high accuracy by utilizing the direct current electrical potential method. The evaluation procedure is carried out by comparing the measured values of electrical potential distribution and those calculated from an analytical method where the crack is modeled as a continuous distribution of 3D double sources. The optimization method is used in order to find accurate solutions. An elliptical embedded crack and a semielliptical surface crack on the back wall in a plate for any aspect ratio of major to minor axes are evaluated especially with respect to location, length and inclination of the crack. The availability of the procedure is verified by some experiments using stainless steels.
  • 嘉納 豊, 阿部 博之
    1992 年 58 巻 547 号 p. 420-425
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    A high accuracy nondestructive procedure utilizing the direct current electrical potential method is proposed to evaluate the 3D shape of a crack in a welded plate. An elliptical embedded crack and a semi-elliptical surface crack on the back wall are evaluated on location, length and inclination of the crack. The change on electrical potential distribution due to the effect of both electrical and geometrical inhomogeneity of the weld is described, and the availability of the calibration method on the effect is verified for an embedded crack with a reinforcement. The evaluation procedure is carried out by comparing the measured values of the electrical potential distribution, which are corrected by utilizing the calibration method, with the calculated distribution in accordance with optimization method. The availability of the presented procedure is verified by experiments using stainless steels.
  • 田村 賢一, 佐藤 和郎
    1992 年 58 巻 547 号 p. 426-430
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    The stress σA at the yield point of mild steel beam of a hollow circular cross section with a radial hole is investigated by experiments, and effects of the radial hole, the outer diameter of the beam and the ratio of inner to outer diameter of the beam upon the yield point are clarfied. Let 2a be the diameter of the radial hole, 2γ1 and 2γ0 be the inner and outer diameters of the beam, and γ1 be γ10, and the experimential data are concluded as follows : (1) In the range of γ1≤0.65, there is a size effect in σA, i.e., σA decreases as 2γ0 increases when γ1 and a/γ0 are kept constant. (2) In the range of γ1≥0.65, γA is affected by 2a, but is free from 2γ0 when γ1 is kept constant.
  • 田村 賢一, 佐藤 和郎
    1992 年 58 巻 547 号 p. 431-435
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    In order to analyze the yield stress in the mild steel beam of a hollow circular cross section with a radial hole shown in the 1st report, it is found that the point of the maximum stress in a beam is varied by the ratio γ1 of inner to outer diameter of the beam. Analyses of the yield stresses of beams supposed a parallel strip to the neutral axis at that point in the range of γ1≤0.65, and supposed an infinite plate at that point in the range of γ1≥0.65 and are then carried out by considering the effect of the surface layer which is inherent for the material. The analytical results agree very closely with the experimental results shown in the lst report. The thickness of the surface layer of the mild steel taken in this case is 0.12 mm.
  • 小久保 邦雄, 長島 英明, 高柳 政明, 間所 学, 望月 明, 池内 壽昭
    1992 年 58 巻 547 号 p. 436-441
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    Cylindrical shells subjected to lateral loads buckle in shear or bending buckling modes. The effects of combined loadings are investigated by developing a special-purpose FEM program using the 8-node isoparametric shell element. Three types of loading, lateral and axial loads, and pure bending moments are considered. For short cylindrical shells, shear buckling modes are dominant, but elephant-foot bulges take place with an increase in bending moments. Effects of axial loads on shear buckling and the elephant-foot bulge are investigated. In the case of shear buckling the axial load affects the buckling mode as well as the buckling load. For bending bucklings, the axial loads have great effect on the buckling load.
  • 柳田 信義, 渡部 修, 桜井 茂雄, 宮田 寛
    1992 年 58 巻 547 号 p. 442-448
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    For an accurate residual life assessment in structural components subjected to cyclic loading, detailed elastoplastic structural analysis is important for areas with strain concentration. The present paper shows some experimental and computational results of elastoplastic behavior for notched plates with different strain concentration factors subjected to two types of zero-to-tension cyclic loadings. Numerical calculation is performed based on the endochronic model for cyclic plasticity, showing good agreements with experimental results.
  • 劉 凱欣, 横山 隆
    1992 年 58 巻 547 号 p. 449-456
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    Numerical solutions are presented for three-dimensional waves in an elastic/viscoplastic bar of square cross section, subjected to a uniform velocity impact. The governing hyperbolic partial differential equations are solved by the method of numerical integration along bicharacteristics. The numerical results for the bar of square cross section are compared with those for that of circular cross section in order to examine the effect of the difference in the shape of the cross section on the wave propagation in the bar. It is shown that the distributions of the longitudinal stress or strain across the transverse section in the vicinity of the impact end of the square elastic bar do not become virtually uniform.
  • 陳 玳〓, 西谷 弘信
    1992 年 58 巻 547 号 p. 457-464
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    In this paper, the singular stress in a wedge-shaped region composed of two materials is studied as a plane problem. An expression is presented for the singular stress field in the vicinity of the corner. When the eigenvalue λ, the root of the eigenequation, is a complex number, the intensity of the singular stress field is defined in terms of two real constants. When A is a real number, the intensity of the singular stress field is defined in terms of one real constant. Based on the numerical results for several special wedges, the mode of singular stress distribution is studied in detail.
  • 京極 秀樹, 益川 庄司, 森 きよみ, 杉林 俊雄, 鈴木 寛, 篠原 和充
    1992 年 58 巻 547 号 p. 465-469
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    Deformation behavior and strength properties of spheroidal graphite cast iron which had been austempered and had various microstructures were studied. The matrix of the cast iron consisted of four kinds : pure ferrite, a mixture of ferrite and pearlite, fully pearlite or a mixture of banitic ferrite and retained austenite. Specimens used were cylindrically hollow tubes which were strained under torsional stresses combined either with tensile or compressive stresses. It was found that the deformation of austempered spheroidal graphite cast iron did not depend much on stress rate in an elastic region, but it depended to an extensive degree on the amount of retained austenite in a plastic region. Fracture strengths of spheroidal graphite cast iron can be predicted by Hoffman's criterion for the specimens having any matrix structure. Fracture morphologies differ quite drastically depending upon their microstructure and upon stress loading conditions.
  • 佐久間 俊雄, 岩田 宇一, 高久 啓
    1992 年 58 巻 547 号 p. 470-475
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    It is essential to evaluate thermal stresses with time and their distribution at quenching in order to estimate the thermal shock resistance of ceramics. Therefore, local heat transfer coefficients during forced convection at quenching in liquid sodium were obtained by experiments and numerical analyses. Using these results, average heat transfer coefficients were obtained as a function of initial temperature of a specimen and quenching medium when a ceramic specimen was falling through liquid sodium. Thermal stresses for a cylindrical body with a conical nose were analyzed numerically using the finite-element method, and maximum tensile stress and stress distributions were indicated in relation to Bi's number.
  • 佐久間 俊雄, 岩田 宇一, 高久 啓, 岡部 永年
    1992 年 58 巻 547 号 p. 476-481
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    Statistical theories of fracture of brittle materials have been applied to ceramics under mechanical loading conditions. In this paper, the retained strength after thermal shock was analysed theoretically and the probability of crack occurrence of ceramics was predicted. In this analysis, the Weibull statistical theory of fracture was applied to thermal shock of ceramics on the assumption that thermal shock fractures of ceramics were due to crack growth from one of the initial flaws. For the purpose of verification of this proposed analysis, thermal shock tests on three kinds of ceramics using liquid sodium as the quenching medium were performed. As a result, analytical results were good agreement with results of thermal shock tests. Thus, the probability of crack occurrence can be evaluated with the normalized fracture strength using effective volume and effective stress hold time.
  • 倉茂 道夫
    1992 年 58 巻 547 号 p. 482-487
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    By using the thermo-poro-elastic theory proposed previously by the author, thermal stresses are analyzed which are induced in a fluid-saturated porous hollow cylinder whose inner surface is heated by burning gas, the wall of which is cooled by the fluid injection from its ourter surface. Two stories of loading conditions are considered : (A) the cylinder is subjected to a sudden rise in temperature of the gas and simultaneously pressurized at its outer surface to cool the wall, and (B) steady state cooling is abruptly disturbed by a sudden loss of pressurization, and after a while it is recovered. Main attention is placed on the effect of heat advection due to active fluid injection on the reduction of temperature and thermal stresses. Since the formulated problem is axisymmetric, the displacement field is decoupled from the temperature and pore-pressure fields, which are still coupled to each other. The coupled nonlinear diffusion equations are solved by the Crank-Nicolson implicit method.
  • 大野 信忠, 王 建定
    1992 年 58 巻 547 号 p. 488-495
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    A kinematic hardening rule formulated in a hardening/dynamic recovery format is examined for simulating ratchetting behavior. This rule, characterized by decomposition of the kinematic hardening variable into components, is based on the assumption that each component has a critical state for its dynamic recovery to be actived. Discussing basic features of the rule, we show that it can predict much less accumulation of uniaxial and multiaxial ratchetting strains than the Armstrong and Frederick rule. Comparisons with classical models such as the multilayer and multisurface models are also made, resulting in a finding that the present rule is similar to the multilayer model with total strain rate replaced by inelastic strain rate. A companion paper deals with applications to the experiments of Modified 9Cr-1Mo steel at 550°C.
  • 大野 信忠, 王 建定
    1992 年 58 巻 547 号 p. 496-502
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    The kinematic hardening rule formulated in the first report of this work is applied to ratchetting experiments of Modified 9Cr-1Mo steel by Tanaka et al. and nonproportional tests along cruciform and circular strain paths. It is shown that this rule is capable of predicting much less accumulation of ratchetting strain under uniaxial and multiaxial loadings than the Armstrong and Frederick rule ; however, if ratchetting strain is negligible, these two rules may give nearly the same predictions. Burlet and Cailletaud's modification of the Armstrong and Frederick rule is also discussed.
  • 〓 桂〓, 谷 順二
    1992 年 58 巻 547 号 p. 503-507
    発行日: 1992/03/25
    公開日: 2008/02/21
    ジャーナル フリー
    The numerical methods which have been proposed by the present authors for investigating the characteristics of waves in a functionally gradient piezoelectric material (FGPM) plate and its transient responses are used to investigate SH waves in FGPM plates. The material properties of the plate change gradually with the thickness of the plate. To evaluate the properties of the energy transfer between the electrical and mechanical energies during acoustic wave propagation in dispersive media, an electromechanical coupling constant is defined on the basis of group velocities of the acoustic waves. Numerical examples are given for a hypothetical FGPM plate and a homogeneous plate. It is found that there are SH surface waves propagating on the softer surface of the FGPM plate. Furthermore, for waves in dispersive media, the electromechanical coupling constant based on group velocities is found to be much better than that based on phase velocities.
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