JSME International Journal Series A Solid Mechanics and Material Engineering
Online ISSN : 1347-5363
Print ISSN : 1344-7912
ISSN-L : 1344-7912
Volume 41 , Issue 3
Showing 1-20 articles out of 20 articles from the selected issue
  • Nao-Aki NODA, Qing WANG, Yoshitaka UEMURA, Yuuji KAWASHIMA
    1998 Volume 41 Issue 3 Pages 303-308
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    This paper deals with numerical solutions of singular integral equations in interaction problems of rectangular inclusions under various loading conditions. The body force method is used to formulate the problems as a system of singular integral equations with Cauchy-type or logarithmic-type singularities, where the unknowns are the densities of body forces distributed in infinite plates having the same elastic constants as those of the matrix and inclusions. In order to analyze the problems accurately, the unknown functions are expressed as piecewize smooth functions using two types of fundamental densities and power series, where the fundamental densities are chosen to represent the symmetric stress singularity of 1/γ<1-λ1> and the skew-symmetric stress singularity of 1/γ<1-λ2>. Then, newly defined stress intensity factors at the end of inclusions are systematically calculated for various shapes and spacings of two rectangular inclusions in a plate subjected to longitudinal tension, transverse tension, and in-plane shear. The present method is found to be effective for accurate and efficient analysis of rectangular inclusions.
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  • Xu WU, Nobutada OHNO
    1998 Volume 41 Issue 3 Pages 309-317
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    A homogenization theory for time-dependent deformation such as creep and viscoplasticity of composites with periodic internal structures is developed. The deviation of microscopic displacement rate from macroscopic one in the macroscopically uniform case, i.e., the first order perturbation of displacement rate in the macroscopically nonuniform case is decomposed into elastic and viscous parts. Thus, the constitutive relation between macroscopic stress and strain rates and the evolution equation of microscopic stress are derived using Y-periodic functions introduced into the elastic and viscous parts, and two unit cell problems to determine the Y-periodic functions are formulated. The theory is described first in the macroscopically uniform case in a rate form, and then it is extended to the macroscopically nonuniform case in an incremental form using the asymptotic expansion of field variables. As an application of the theory, transverse creep of metal matrix composites reinforced unidirectionally with continuous fibers is analyzed numerically to discuss the effect of fiber arrays on the anisotropy in such creep.
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  • Ryusuke KAWAMURA, Yoshinobu TANIGAWA
    1998 Volume 41 Issue 3 Pages 318-325
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    In this paper, one-dimensional transient heat conduction and thermal bending problems under an axisymmetric condition are developed theoretically for a functionally graded circular plate due to a uniform heat supply from its surfaces. We construct the approach for the multipurpose optimization of the nonhomogeneous material composition in a functionally graded circular plate considering the relaxation of the thermal stress distribution and the improvement of the heat resistance. We deal with this multipurpose optimization using the weighting method. Using these analytical solutions for the temperature field and the associated thermoelastic one, and the approach for the multipurpose optimization of the nonhomogeneous material composition, numerical calculations of the optimal material composition are carried out for a titanium alloy(Ti-6 Al-4 V)/zirconium oxide(ZrO2) functionally graded circular plate subjected to a uniform heat supply from one side of its surface. The trade-off relationship between the maximum absolute stress ratio and the maximum heat flux is elucidated. It is shown that this approach is useful for the multipurpose optimal design of nonhomogeneous material composition considering both the securement of strength against thermal stress and the improvement of heat resistance against thermal load.
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  • Noboru NAKAYAMA, Masahiko OHASHI, Hiroyuku TAKEISHI
    1998 Volume 41 Issue 3 Pages 326-331
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    A method of measuring the maximum dynamic stress concentration factor αDmax in a fillet has not yet established. The reflection and transmission of stress wave during the propagation through a fillet result in complex stress states. We propose a new method for analyzing the maximum dynamic stress concentration factor αDmax in a fillet utilizing the stress concentration factor αS and the reflection coefficient A obtained by a strain gauge on the incident strip plate. In this experiment, a square wave(a stress wave with a plateau of constant stress for long duration)is used. A strain gauge measures the reflection coefficient A. The factor αDmax in the fillet is analyzed using a dynamic photoelastic method. It is confirmed that αDmax is approximated by the following equation:αexDmax=(1+A)αS. As a result, the maximum dynamic stress concentration factor is obtained experimentally using the static stress concentration factor and the reflection coefficient.
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  • Toshihiko HOSHIDE, Akira NEBU, Kenji HAYASHI
    1998 Volume 41 Issue 3 Pages 332-337
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    Bending strength of ceramics coated glass was investigated from two aspects, concerning effects of the sputtering condition and the difference of target material on the strength. In this work, a borosilicate glass was coated with an alumina or a silicon carbide by a radio-frequency magnetron sputtering method under various conditions. Three-point bending tests of coated materials and the glass substrate were carried out. The strength of coated material was improved compared with that of the glass substrate. The scatter in the strength of coated materials appeared to be comparable with of less than the strength scatter of the glass substrate. Although monolithic alumina is usually weaker than monolithic silicon carbide, the strength of alumina coated materials was found to be higher than that of silicon carbide coated materials. This tendency was explained by a tensile thermal stress generated in silicon carbide coated materials, in which substrates were initially pre-heated.
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  • Hidetoshi KOBAYASHI, Masashi DAIMARUYA, Tamio KOBAYASHI
    1998 Volume 41 Issue 3 Pages 338-344
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    In order to investigate the effect of loading rate on the strength and the absorbed energy of paper honeycomb cores, a series of compression tests were carried out at quasi-static and dynamic rates. The specimens used are polypropylene(PP) and polyester(PET) thermoplastic honeycomb cores, which are usually called paper honeycomb cores. It was found that the peak stress and average crush stress increased with the increase of loading rate and was especially remarkable in the results of the PP core. The absorbed energy obtained from dynamic tests was also greater than that obtained at quasi-static rates. It was ascertained that the polyvinyl chloride(PVC) long tube was quite useful as a device for measuring stress waves in dynamic compression tests, if the characteristics of the wave propagation in the PVC tube are obtained by preliminary wave propagation experiments, specifically to determine the rate of decrease in amplitude and/or the propagation velocity.
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  • Kenji HATANAKA, Kenichi OSHITA, Hirohisa SHIOTA
    1998 Volume 41 Issue 3 Pages 345-351
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    A tensile creep specimen with projections was designed to measure creep displacement by means of the laser-beam displacement meter at temperatures elevated over 1000°C. Stress/strain concentrations, however, occur around the root of projections in this specimen. The high-temperature creep strain was determined from the measurement of tensile displacement between the two projections by correcting influence of the projections. The procedures used to determine the steady-state creep constitutive equation of Si3N4 ceramics was proposed by combining a high-temperature creep test using the specimen with projections and the finite-element method(FEM) calculations for the specimen. Furthermore, the method for designing the optimum creep specimen with projections was determined via the FEM calculations using the steady-state creep constitutive equation.
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  • Akira SHIMAMOTO, Makoto KOSAI, Albert S. KOBAYASHI
    1998 Volume 41 Issue 3 Pages 352-358
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The crack arrest capability of a tear strap in a pressurized precracked fuselage was studied through instrumental axial rupture tests of small-scale models of an idealized fuselage. Upon pressurization, rapid crack propagation was initiated at an axis through crack along the stringer and immediately kinked due to the mixed mode I and II states caused by the one-sided opening of the crack flap. The diagonally running crack turned at the tear straps. Dynamic finite element analysis of the rupturing cylinder showed that the crack kinked and also ran straight in the pressure of a mixed mode state according to a modified two-parameter crack kinking criterion.
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  • Tetsuo KINJO, Hiroaki SUZUKI, Mikio TAKEMOTO
    1998 Volume 41 Issue 3 Pages 359-365
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    With the aim of studying the effect of glass fiber/matrix interfacial quality on the dynamics of microfractures in GFRP, we propose a new source simulation of dissipative elastic waves. We measured the out-of-plane displacements by the longitudinal wave(P-wave)using a developed AE monitoring system and computed them by the convolution integral of assumed fracture dynamics with the analytical transfer function of the medium(Green' function of the second kind), by taking into account both the orientation dependence of velocity and attenuation of the P-wave. We also propose a new computer algorithm for estimating the source locations and fracture modes by using the arrival time and radiation pattern analysis of the P-wave. The first report introduces the proposed AE source characterization algorithm and acoustic properties of an unidirectional GFRP. Macroscopic elastic properties of UD-GFRPs with different interfacial qualities prepared by adding a small amount of paraffin wax are also reported in this paper.
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  • Tetsuo KINJO, Hiroaki SUZUKI, Mikio TAKEMOTO
    1998 Volume 41 Issue 3 Pages 366-371
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    Based on the AE source simulation method proposed in the first report, we studied the dynamics of microfractures in unidirectional GFRPs with different interfacial qualities. Three types of microfractures were revealed by the AE source simulation. AE event counts due to the Mode-I fiber fracture, Mode I and II interfacial fractures(debonding and disbonding)were observed at higher stresses in UD-GFRP with poor interfacial qualities(with wax in matrix)than in UD-GFRP with good interface quality, but increased rapidly with an increase of stresses. Dynamics of microfractures changed depending on the interfacial qualities.
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  • Naoya TADA, Yoshihito HAYASHI, Takayuki KITAMURA, Ryuichi OHTANI
    1998 Volume 41 Issue 3 Pages 372-379
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The electric field in a conductive material with multiple circular cracks was analyzed by means of crack-flow modification method(CFMM). It was found by the analysis that the increase in potential difference of the cracked material normalized by the potential difference without cracks, ΔV/V0, was in proportion to the product of the effective volumetric crack density and the mean of cubed crack radius, neff3]m. This universal relationship was also valid for multiple semi-circular cracks distributed on the surface of the material and gave the physical meaning of damage detected by the direct current electrical potential method.
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  • Kimiyoshi NAITO, Toru FUJII
    1998 Volume 41 Issue 3 Pages 380-388
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The effects of rubber modification and adhesive thickness on the fatigue-fractured surfaces of epoxy adhesives under mode I cyclic loading were examined using fractals. When the energy release rate range, ΔGI, is higher than 100 J/m2, the fractal dimension of fractured surfaces becomes high due to rubber modification. The fractal dimension decreases with increasing fatigue crack growth rate, da/dN. The following equation shows the relationship between parameter S(=da/dN·ΔGI)and fractal dimension D for unmodified and rubber-modified adhesives. log S=log(da/dN·ΔGI)=α4·D+β4 Here, α4 and β4 are experimental constants. Regardless of whether the adhesives contain rubber particles or not, the fractal dimension as well as the da/dN-ΔGI relation is little affected by adhesive thickness.
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  • Weiping LIN, Yoshio ARAI, Eiichiro TSUCHIDA
    1998 Volume 41 Issue 3 Pages 389-394
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    Fatigue strength and crack propagation characteristics of ceramic/metal joints were investigated under cyclic bending loading. Fracture surfaces were examined by SEM and X-ray methods. Fatigue fracture occurred at the metal/interlayer interface as well as the ceramic/interlayer interface. Fatigue strength was independent of the fracture path. Fatigue crack initiated and grew on the ceramic/interlayer interface at the specimen corner. Under constant amplitude cyclic loading, the fatigue crack decelerated and finally halted. Under increasing amplitude cyclic loading, the final fracture occurred at the metal/interlayer interface. Even under cyclic compressive loading, fatigue cracks were initiated on the ceramic/interlayer interface.
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  • Panagiotis FRANTZIS
    1998 Volume 41 Issue 3 Pages 395-404
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The environmental failure of double-torsion(DT) mild steel adhesive joints was investigated with particular emphasis on the behaviour of the metal oxide/adhesive interface. The joints had previously been subjected to static loading in moist conditions using specifically built apparatus. Modern surface-sensitive analytical techniques, such as scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS), were employed to examine the resulting failure surfaces and to assess the effect of the environment.
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  • Panagiotis FRANTZIS
    1998 Volume 41 Issue 3 Pages 405-415
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The environmental failure of double-torsion(DT) mild steel adhesive joints was investigated with particular emphasis on the process of water transmission at the interface of these joints. The joints had previously been subjected to static loading in moist conditions using specifically built apparatus. The present work is an attempt to identify this process and relate the observed changes in DT joint performance to the rate of water ingressing into the adhesive layer and the solubility of the epoxide systems.
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  • Kenji SUZUKI, Keisuke TANAKA, Yoshihisa SAKAIDA
    1998 Volume 41 Issue 3 Pages 416-421
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The sin2 ψ diagram taken from a specimen with steep stress gradients beneath the surface shows nonlinearity, because the X-ray penetration depth changes depending on the tilt angle. Stress gradients can be determined from this nonlinearity. Since ceramic materials have deep X-ray penetration depth, the thickness of a ceramic thin film should have a significant effect on the nonlinearity of the sin2 ψ method. In this paper, we propose a method of X-ray measurement of the stress gradient, which takes into account film thickness under the assumption of linear stress distributions. A 58-μm-thick silicon nitride film was prepared. The film specimen was polished carefully with diamond slurry to obtain sharp profiles of the X-ray diffraction. To obtain a steep stress gradient, the specimen was bent on a cylinder. The stress distribution estimated by the present method agreed well with the applied bending stress. In conclusion, the stress gradient should be analyzed by the weighted average stress on the basis of the intensity of the diffracted X-rays from the entire thin film, when the thickness is six times larger than the effective X-ray penetration depth.
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  • Yoshihisa SAKAIDA, Keisuke TANAKA, Yuichi IKUHARA, Kenji SUZUKI
    1998 Volume 41 Issue 3 Pages 422-429
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The residual stress distribution of ground ceramics was determined from the eigen strain distributed near the ground surface. The eigen strain of ground ceramics was tensile, and exponentially decreased with the distance from the surface. The residual stress distribution is given as a superposition of an exponential function of compression and a linear function. It is found that the actual residual stress distribution can be approximated by an exponential function of compression because the magnitude of tensile residual stress is negligibly small compared to the compressive residual stress. In the experiments, the diffraction angle was measured on ground silicon nitride for a wide range of sin2 ψ using the glancing incidence X-ray diffraction technique. A strong nonlinearity was found in the 2θ-sin2 ψ diagram at very high ψ-angles. From the analysis of nonlinearity, the residual stress distribution was determined. The residual stress distribution of silicon nitride coincided with the distribution calculated from the eigen strain distribution. Transmission electron microscopy was used to clarify the origin of generation of the residual stress. Both strain contrasts and microcracks were observed below the ground surface;straight dislocations were also observed within silicon nitride grains near the ground surface.
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  • Masahiro NISHIDA, Tomio ENDO, Tadaharu ADACHI, Hiroyuki MATSUMOTO
    1998 Volume 41 Issue 3 Pages 430-438
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    In this paper, a new method is suggested for the nondestructive measurement of elastic moduli on the local surface of an anisotropic material by an amplitude and phase acoustic microscope. It is confirmed that the anisotropic wave velocities in a local area are determined from the complex V(z)curve measured by a line-focus acoustic lens. The experimental analyses were carried out for single crystal of cubic system, (001)face of gallium arsenide, with water or mercury as the coupler. The velocity of the surface wave was clearly seen when the acoustic impedance of the coupler was smaller than that of the specimen. The velocity of the longitudinal wave was successfully measured, provided the acoustic impedance of the coupler was comparable to that of the specimen. Then, the elastic moduli in a single crystal of gallium arsenide was determined from the measured longitudinal and surface wave velocities according to elastodynamic theory. It was shown that the present method is very useful in determining the anisotropic elastic moduli of a cubic system in a local area.
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  • Hideo CHO, Singo OGAWA, Kazushi YAMANAKA, Mikio TAKEMOTO
    1998 Volume 41 Issue 3 Pages 439-445
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The elastic properties of TiN films deposited on stainless steel SUS317J2 by three physical vapor deposition methods were estimated from the velocity dispersion of laser surface acoustic waves(SAWs) in the frequency range of 30 to 60 MHz. The velocity dispersion of Rayleigh waves was obtained by the scanning interference fringes(SIF) system and was used to estimate the elastic stiffness of the films. Depending on the deposition method, Young's moduli of TiN films were found to increase in the order of activation reaction method(ARE) → hollow cathode discharge(HCD) → arc ion discharge(AID) method. The attenuation of SAWs was the highest for AID film due to the poor quality of the film.
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  • Singo OGAWA, Hideo CHO, Kazushi YAMANAKA, Mikio TAKEMOTO
    1998 Volume 41 Issue 3 Pages 446-451
    Published: July 15, 1998
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    Damage progression of vapor-deposited TiN films on SUS317J2 steel under compressive loading was estimated by continuous monitoring of acoustic emission(AE). AE source inversion revealed that the film fracture progresses as follows:(1)Mode-II delamination at the edge of the TiN film during elastic strain, (2)Mode-I delamination of TiN due to the emergence of a slip step in the plastic region, and (3)Mode-I film fracture which allows the penetration of corrodent. The threshold strain that causes film damage was correlated with the mismatch of the elastic modulus of the TiN film to that of the substrate metal.
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