Transactions of the Japan Society of Mechanical Engineers Series A
Online ISSN : 1884-8338
Print ISSN : 0387-5008
Volume 52, Issue 482
Displaying 1-20 of 20 articles from this issue
  • Keiro TOKAJI, Zenji ANDO
    1986 Volume 52 Issue 482 Pages 2319-2323
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    Fatigue crack retardation behaviour was investigated in saltwater using two materials of a low alloy steel, SCM435, whose strength or susceptibility to hydrogen was changed by heat treatment, and was compared with the data in laboratory air. The results show that there exists a significant difference between the overload affected zone sizes in saltwater and in air, depending on both the strength of the material and the baseline stress intensity level. The decreased overload affected zone size in lower strength material is related to a rapid resumption of the crack propagation rate after the minima, due to hydrogen embrittlement (HE) and corrosive dissolution. In higher strength material, in addition to a rapid resumption of the crack propagation rate due to the extreme HE, the overload affected zone size is also affected by the existence of SCC crack propagation caused by the overload application because of overload stress intensities above the KI SCC value of this material.
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  • Yozo SAWAKI, Shuji TADA, Tadashi KAWASAKI, Shizuo NOMURA
    1986 Volume 52 Issue 482 Pages 2324-2330
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
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    The effect of stress ratio, frequency and temperature on the corrosion fatigue crack growth rate of high strength steel has been examined in a 3.5% sodium chloride solution. Corrosion fatigue crack growth data (da/dN - ΔK) observed in the middle range of stress intensity are well expressed by the parallel curve of the data obtained under the conditions of the laboratory air. It is found that the parallel data obtained between these two environments are the results of the reduction of fatigue fracture toughness in corrosive environment. The decreased fracture toughness value is named as an environmental fatigue fracture toughness, Kfe. The hydrogen permeating into the plastic zone at the crack tip is thought to be the main reason for this toughness reduction. It is shown that the Kfe successfully explains the acceleration of fatigue crack growth rate in aqueous environment.
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  • Yasuhiro KANTO, Takashi MISHIBA, Takashi SUENAGA, Hiroomi HOMMA
    1986 Volume 52 Issue 482 Pages 2331-2334
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    In the primary piping systems of nuclear power plants, many valves with bellows in their seal systems are used in order to prevent the leakage of high-pressurized and high-radioactive coolant. The Ω-bellows for high-pressure valves hold rings in them in order to heighten their compressive stiffness and reduce their stresses. The contact and frictional effects between the bellows and the rings prevent their stress analyses. In this paper, we analyzed the stresses in Ω-bellows using the finite element program applicable to contact problems, and then estimated the fatigue strength for 4 types of loading histories. The effect of the thickness of the bellows was investigated in two compressive types of loading. The reponses of two tensile types of loading were compared with the above results.
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  • Michio KURASHIGE
    1986 Volume 52 Issue 482 Pages 2335-2341
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
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    The Bifurcation problem stated in the title is analyzed on the basis of the mechanics of incremental deformations. The cylinder is reinforced by ixextensible, completely flexible fibers in the direction of its axis. It is found that the smallest critical compression is equal to the shear modulus for infinitesimal deformations and does not depend on any dimensions of the cylinder. The associated bifurcation mode is that for n=1, n being the number of circumferential node. When it bifurcates, the singular stresses appear in the boundary fiber surfaces.
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  • Hideo KOGUCHI, Junichi SATO, Masayuki SIMA
    1986 Volume 52 Issue 482 Pages 2342-2350
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
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    Fretting damaged surfaces of PMMA (polymethyl methacrylate) and steel balls in contact are directly and microscopically observed by optical microscope for various level of normal load, amplitudes of steel balls and fretting frequencies. It is found that corrugation occurs on the surface of PMMA during fretting and it is closely related with the wear of steel balls. After the initiation of corrugation, two types of wear are observed in our experiments : (a) the steel ball continues to slide on PMMA and the wear debris of the steel ball is enveloped in the softened PMMA ; and (b) the steel ball adheres to the corrugation and the wear debris accumulates at the boundary of adhered area. To study the cause of corrugation, the distribution of temperature of the fretting surface is numerically analyzed by the nonlinear transient heat conduction equation with the heat generated by the dissipation of energy during fretting. As a result, the increase of temperature by the dissipation of energy is very little, and it may be attributed to the viscoelastic property of PMMA.
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  • Hiroomi HOMMA, Kohji MITSUBAYASHI, Kazuhiko TAKIHARA
    1986 Volume 52 Issue 482 Pages 2351-2355
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    In this paper, stable crack growth is examined in both experimental and analytical ways to establish a test method to evaluate the fracture toughness of FRP. The mechanism of stable crack growth is considered from observations of vicinity of the crack tip. There is always a damage zone in which debonding between the fibers and the matrix occurs ahead of the crack tip. Crack growth occurs by breaking the fibers at the crack tip. Stress analysis is carried out to find out how much stress is applied to the fibers in the damage zone. A line spring model is used to express the mechanical behavior of the fibers in the damage zone, and infinitesimal dislocation distribution theory is used in the numerical stress analysis. It is concluded that stable crack growth in a fracture toughness test of FRP is inherently different from that in metallic materials induced by plastic deformation near the crack tip ; that it results from the stress relaxation by debonding between the fibers and the matrix ; and that the stress intensity at the point of instability in the fracture toughness test is the material property.
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  • Toshimi KANNDO, Hideki SEKINE, Osamu TAMATE
    1986 Volume 52 Issue 482 Pages 2356-2363
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    The plane stress problem of a thin elastic stiffener of finite length bonded to the edge surface of an anisotropic semi-infinite plate containing an internal crack is analyzed. In the analysis the singular point method is adopted. By the replacement of the stiffener and the crack with continuous distributions of concentrated forces and edge dislocations, respectively, we obtain a system of singular integral equations. Numerical calculations are performed to clarify the effects of the rigidity of the stiffner, anisotropy and the geometrical parameters of crack arrangement on the stress intensity factors at the tips of the crack, and the results are shown in figures.
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  • Fumihiro ASHIDA, Naotaka NODA
    1986 Volume 52 Issue 482 Pages 2364-2370
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
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    The present paper is concerned with the transient thermal stress in a transversely isotropic infinite solid containing a penny-shaped crack with heat exchange on the crack surface. This problem is analyzed by means of the finite differences method with respect to only time variables and by the transversely isotropic potential functions method with respect to stress. The numerical calculations of the stress intensity factor were carried out for a graphite which belongs under transverse isotropy. The effects of the various anisotropies of the material properties on the stress intensity factor are shown in figures.
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  • Fumihiro ASHIDA, Naotaka NODA
    1986 Volume 52 Issue 482 Pages 2371-2377
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    The present paper deals with the transient thermal stress in a transversely isotropic infinite solid with an external crack subjected to heat exchange and heat absorption which depends on position and time. It is very difficult to obtain the analytical solution for the temperature field so that the finite difference method with respect to time variable only is introduced. Thermal stress is analyzed by means of transversely isotropic potential functions method. The numerical calculations of the stress intensity factor were carried out for a graphite which belongs under transverse isotropy. The effects of Biot numbers on the stress intensity factor are shown ion figures.
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  • Ichiro TAKAHASHI, Saburo USAMI, Takashi MACHIDA
    1986 Volume 52 Issue 482 Pages 2378-2386
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    Crack growth behavior from an artificial defect in sintered silicon nitride was measured under static fatigue at room and at elevated temperatures. The static fatigue strength decreased with an increase of the time and approached a constant value over 103 to 104 s, which was defined as the static fatigue limit. The static fatigue crack growth rate, which did not bear a close relation to the stress intensity factor, decreased at the first stage and increased at the second stage for the broken specimen. For the un-broken specimen, it decreased monotonically, then arrested at the second stage. This confirmed the existence of a static fatigue limit. The crack at the 1 000°C in the air was similar to the behavior in the vacuum. On the other hand, the static fatigue limit in the humid air decreased to the 70% of the short time strength. However, the static fatigue limit in the vacuum did not decrease at room temperature.
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  • Tatsuya ISHIBASHI, Shigeru SHIMODA
    1986 Volume 52 Issue 482 Pages 2387-2394
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    In order to correlate hardness Pm by the spherical indenter with the flow stress Y, it is necessary to determine the total mean strain of the indentation, which corresponds to the total strain in a uniaxial stress field. Firstly, the total mean strain of the indentation εic is defined, by means of multiplying the total corresponding strain coefficient of the indentation Cεc by the total profile coefficient of the indentation (d/Dc) at the end of the plastic flow of a specimen ; εic=Cεc (d/Dc). Then Hardness/Flow stress ratio C is obtained experimentally, C=9.8 Pm/Y, Y in MPa, and formulated as follows ; C=1.1+(2/3) ln (εic·Es/Y), Es is the Young's modulus of a specimen. Further, an example of the flow stress-strain characteristic curve of SUS 304 specimen is shown in a wide range of the strain by means of a calculation using this formula and the former reported formula ; Pm=Pup(d/Dp)xp, etc..
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  • Shigeo TAKEZONO, Katsumi TAO, Hiroo UCHIBORI
    1986 Volume 52 Issue 482 Pages 2395-2403
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    An analytical method for the elasto/visco-plastic dynamic problems of general moderately thick shells of revolution is developed in consideration of the effect of shear deformation and rotatory inertia. The equations of motion and the relations between the resulting stresses and displacements are derived by extending the Naghdi theory in elastic shells with given consideration to the effect of shear deformation and rotatory inertia. For the constitutive relations, the elasto/visco-plastic equations by Fyfe based on the model developed by Perzyna are employed. The numerical method selected for this problem is a method using finite difference in both space and time. As a numerical example a cylindrical shell under a semisinusoidal internal pressure with respect to time is analyzed, and the results are compared with those from the theory which neglects the effect of rotatory inertia.
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  • Tadashi HORIBE
    1986 Volume 52 Issue 482 Pages 2404-2409
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    This paper is concerned with the large-deflection analysis of extensible beams that have discontinuities in cross-sectional properties by the integral equation method. Since the governing equation of the large-deflection problems of extensible beams has a non-linear form, it is difficult to analyse the problems by the conventional integral equation method. In a previous paper we proposed the iterative scheme that has the numerical stability to solve such problems. In this paper we apply the proposed scheme to the large-daflection problems of discontinuous, extensible beams. A number of numerical examples of beams with various edge conditions are analysed for deflections, and the influence of discontinuities on the non-linear properties of extensible beams is discussed.
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  • Masaro IZUMISAWA, Yasuo NAGASE, Kazuyasu FUKUI
    1986 Volume 52 Issue 482 Pages 2410-2415
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    In the copper electroplating method of stress analysis, frequency effects of cyclic stresses on the proper stress τp for grain growth and slip-initiation in the copper plating foil, and τs for slip-initiation in the copper foil were investigated within the range of 1∼15 kHz. The following results were obtained : (1) The proper stress τp increases and grown grains appear finely with an increase in frequency. (2) τp depends on strain rate remarkably as compared with τs. (3) This is due to the fact that the grain growth in the plating foil is dominated by both the test period and strain rate for the slip in crystals, while the slip-initiation in the copper foil is dominated only by the strain rate. (4) The relation between τp for grain growth and the test period is represented by one curve, regardless of the frequency within 1∼150 Hz.
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  • Hitoshi WATA, Zenji ANDO, Tohru NISHIMURA
    1986 Volume 52 Issue 482 Pages 2416-2421
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    A simple procedure for obtaining a stress intensity factor using FEM proposed by the authors was applied to analyze the problem of a lug with cracks. First, to confirm its usefulness for the present method, a problem for a rectangular plate with an edge crack subjected to three point bending was calculated by the present method. The present results were compared with present photoelastic experimental results or usual results. Next, a dynamic calculation for the same problem and a problem for a lug with cracks were carried out by the present method, and the results were compared with the present experimental results using a strain gaga method. Consequently, as the usefulness of the present method was recognized, the static and the dynamic stress intensity factor of the lug with cracks was investigated by the present method varying a pin hole diameter or a crack length systematically. Furthermore, the relation between the static stress intensity factor and the dynamic one was presented.
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  • Kenichi KOBAYASHI, Teruyoshi UDOGUCHI
    1986 Volume 52 Issue 482 Pages 2422-2428
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    This paper describes uniaxial cyclic elastic follow-up tests carried out on austenitic stainless steel SUS 304 at 700°C, and analyses of the test results. In the present tests, more of the starting points of elastic follow-up strain were beyond the elastic limit of the material. The analysis for stress and strain behavior which progressed under uniaxial elastic follow-up tests was performed by similar methods proposed in the previous paper. The stress and strain in the cyclic elastic follow-up process were estimated by an inelastic analysis based on Norton's law applied to a modified triangle of elastic follow-up. The agreement of the analysis and the experiment was very good. The plastic strain range, produced in the hysteresis loop, depended upon the stress which was elastically calculated on the triangle of elastic follow-up. The cyclic elastic follow-up behavior could also be estimated conservatively from the inelastic analysis.
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  • Masanori KURITA, Matsuo MIYAGAWA, Kenzo CHIAKI, Isao SAKAMOTO
    1986 Volume 52 Issue 482 Pages 2429-2435
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    When annealed metals are cold worked, their diffraction lines broaden due to nonuniform lattice strain and small particle-size. The broadening of the diffraction line caused by plastic deformation was measured by using the Gaussian curve parameter (GCP), which is a constant in a Gaussian curve fitted to the diffraction peak and can be determined from only five to fifteen X-ray intensities around the diffraction peak. Annealed mild steels were plastically deformed by tension, compression, and torsion. The GCP increases with increasing logarithm of equivalent strain along a straight line for all the specimens. The use of the GCP allows a rapid and nondestructive measurement of plastic strain in annealed mild steels. The relationship between the GCP and the half-width is also given.
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  • Shohachi WAKASUGI
    1986 Volume 52 Issue 482 Pages 2436-2442
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    The constitutive relationships of elastic / viscoplastic materials are discussed theoretically over a wide range of stress, temperature and plastic strain rates. Linear constitutive relationships between stress, the reciprocal of absolute temperature and the logarithm of plastic strain rate is assumed in any field of the above mentioned variables. The boundaries separating the various fields appear as straight lines, and two types of constitutive relationships bending convexly or concavely at the boundaries appear. These results explain the experimental results well. The mathematical model which explains them is presented.
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  • Katsufusa NARUSE
    1986 Volume 52 Issue 482 Pages 2443-2450
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    The onset of wrinkling in elastic-plastic bending of circular plates subjected to moments uniformly distributed along the outer edge is investigated theoretically as a bifurcation problem. Based on the numerical prebifurcation solutions obtained by the use of large deflection theory (relating to) thin plates, nonaxisymmetric bifurcation of deformation is analyzed approximately employing the principle of virtual work for finite deformation. The effects of disc geometry and material properties on bifurcation are clarified, including wave number. These theoretical results are qualitatively compared with experimental ones obtained previously in deep-drawing or cup-forming by bending with a hemi-spherical punch and die.
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  • Sei UEDA
    1986 Volume 52 Issue 482 Pages 2451-2458
    Published: October 25, 1986
    Released on J-STAGE: February 21, 2008
    JOURNAL FREE ACCESS
    This paper deals with the dynamic interaction of two parallel penny-shaped cracks in a layered composite under the incidence of torsional impact wave. The delay of arrival time of the incident wave and the reflected waves between two interfaces are considered in this study. Laplace and Hankel transforms are used to formulate the problem as the solution of a set of simultaneous dual integral equations. The simultaneous dual integral equations are reduced to simultaneous Fredholm integral equations of the second kind, whose solution are obtained by utilizing the Gauss's formula. A numerical Laplace inversion routine is used to recover the time variation of the solution. The dynamic stress intensity factors are obtained for several values of time, material constants and geometric parameters.
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