JSME International Journal Series A Solid Mechanics and Material Engineering
Online ISSN : 1347-5363
Print ISSN : 1344-7912
ISSN-L : 1344-7912
Volume 42 , Issue 4
Showing 1-23 articles out of 23 articles from the selected issue
  • Theodore R. TAUCHERT, Fumihiro ASHIDA, Naotake NODA
    1999 Volume 42 Issue 4 Pages 452-458
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    Reference is made to investigations by various authors dealing with piezothermoelastic response of beams, plates, shells and adaptive structural systems. The emphasis of this paper is, however, directed at solutions to inverse problems considered by the present authors during the past few years. A solution procedure based on displacement and electric potentials is reviewed, and the determination of unknown thermal loadings inferred from prescribed electric potential differences is illustrated for a number of cases.
    Download PDF (818K)
  • Robert G. PAYTON
    1999 Volume 42 Issue 4 Pages 459-462
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The partial differential equation describing the shape of the wave front caused by a two-dimensional point impulsive source in transversely isotropic elastic media is formulated and solved. The important role played by the slowness curve in establishing key features of the wave front is discussed. Recent research on the existence of slowness curve inflection points, experimental verification of anisotropic elastic wave front shapes in crystals, and the wave front from a circular distributed source are briefly discussed.
    Download PDF (602K)
  • Akihiro NAKATANI, Hiroshi KITAGAWA, Makoto SUGIZAKI
    1999 Volume 42 Issue 4 Pages 463-471
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    In the present study, the 2-dimensional discrete dislocation dynamics(DDD) simulation is applied to crack tip field under cyclic loading. The crack is located on bcc(body centered cubic) iron subjected to the mode I crack opening load. The crack front is taken in[11^-0]direction and the plane strain assumption confines the number of active slip system to two((1^-1^-2)[111], (112)[111^-])of the 48 proper bcc slip systems. The angles θ between the slip direction and the direction of the crack extension are set 54.7° and 35.3°. The plastic deformations, obtained by different computational methods(molecular dynamics, DDD, and FEM based on crystal plasticity)in different scales are compared mutually. The shapes of plastic region, obtained by the DDD and the FEM based on crystal plasticity qualitatively correspond with each other. Under cyclic loading, the number of nucleated dislocations is almost balanced to the number of annihilated/disappearing dislocation so that the number of current dislocations is almost constant through the simulation. The cleavage stress at crack tip is increasing during this steady state. This seems to give some useful informations of ductile-brittle transition in fatigue crack extension by the DDD approach.
    Download PDF (1350K)
  • Chai GUOZHONG, Masaki SHIRATORI
    1999 Volume 42 Issue 4 Pages 472-478
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    Extending the engineering approach for elastic-plastic fracture analysis(EPRI approach)to creep crack analysis, in this study we examine an engineering approach for estimating the displacement, crack-tip J and C integrals under nonsteady creep conditions. On the bases of the proposed engineering approach and the elastic-plastic line-spring method, a creep line-spring method is proposed and the fundamental equations are established. The creep line-spring method is used for estimating the creep fracture parameters for three-dimensional creep cracks. In order to check its accuracy, several surface-cracked plates under uniform tension are analyzed by the creep line-spring method and the three-dimensional finite-element method. The numerical results show that the creep line-spring method is in good agreement with the finite-element method and has the same accuracy as the common elastic-plastic line-spring method.
    Download PDF (813K)
  • Yukuo NANZAI, Akihiro MIWA, Shan Zi CUI
    1999 Volume 42 Issue 4 Pages 479-484
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    Aging in quenched and strained polymethyl methacrylate(PMMA) has been studied using a differential scanning calorimetry(DSC) and a thermally stimulated deformation recovery measurement as well as a mechanical compression test. The aging in quenched and strained PMMA was compared with the physical aging in quenched PMMA with no strains. The PMMA samples strained in compression before the aging showed an evolution of yield stress with aging time much faster than that in quenched samples with no strains. The DSC analysis, however, showed that the endothermic peak for the quenched and strain-aged PMMA was less developed than that for the quenched PMMA with no strains. This paradox was analyzed using the deformation recovery data for quenched and strain-aged PMMA. The analysis led us to the conclusion that the evolution of yield stress in quenched and strain-aged PMMA is probably due to the structural change locking the strain energy tightly in the polymeric structure.
    Download PDF (762K)
  • Noriyuki MIYAZAKI, Yasuko KURODA
    1999 Volume 42 Issue 4 Pages 485-491
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    A computer code was developed for simulation of dislocation density in a bulk single crystal during the Czochralski(CZ) growth process. In this computer code, the effects of crystal anisotropy such as the elastic constants and slip directions were approximately taken into account by averaging the Young's modulus, the Poisson's ratio and the resolved shear stress along the azimuthal direction. Axisymmetric finite element analysis can be applied to quantitative estimation of dislocation density during single crystal growth process by using such averaging technique together with the Hassen-Sumino model as a creep constitutive equation of a single crystal at elevated temperatures. Dislocation density analyses were performed for both the[001]and [111]growth directions of an InP single crystal. As a result, although the[111]growth direction has the larger average Young's modulus than the[001]growth direction, the former gives lower dislocation density than the latter.
    Download PDF (925K)
  • Masayuki ISHIHARA, Naotake NODA
    1999 Volume 42 Issue 4 Pages 492-498
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    In this study, we treat a two-dimensional electroelastic problem of an infinite piezoelectric body with two circular piezoelectric inhomogeneities. We consider that two inhomogeneities may have different dimensions and material properties and that the body is subjected to out-of-plane shear deformation and in-plane electric field at infinity. The electroelastic field in both matrix and inhomogeneities is obtained analytically by introducing two complex potential functions and conformal mapping. We find that the electroelastic field in inhomogeneities is not uniform. Some numerical examples are shown graphically and the influence of micromechanics parameters on the distributions of stresses and electric fields is discussed qualitatively and quantitatively.
    Download PDF (811K)
  • Ryusuke KAWAMURA, Yoshinobu TANIGAWA, Hideki WATANABE, Katsuyuki YAMAS ...
    1999 Volume 42 Issue 4 Pages 499-506
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    This paper is concerned with theoretical treatment of thermal buckling of thinwalled strip subjected to partially distributed moving heat source and uniform tensile stress in the longitudinal direction. First, heat conduction is treated as one-dimensional and quasi-stationary problem assuming that intensity and velocity of moving heat source are constant with time, and that temperature distribution is one-dimensional. Next, equation of equilibrium and equation of compatibility of strain in thinwalled plate are formulated by making use of the von Karman large deflection plate theory. And making use of the generalized double Fourier series, nonlinear simultaneous algebraic equations are derived with respect to in-plane thermal stress function and out-of-plane displacement. Then nonlinear simultaneous equations are solved by the Brent method as numerical solution. Effects of uniform tensile stress, aspect ratio and thickness of plate, velocity and area of moving heat source, upon buckling start temperature and post-bucking behavior are examined through numerical calculations.
    Download PDF (961K)
  • Masahiro ARAI, Tadaharu ADACHI, Hiroyuki MATSUMOTO
    1999 Volume 42 Issue 4 Pages 507-514
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    In the present paper, the boundary element method(BEM) for unsteady elastodynamic problems based on the Laplace transform is discussed. In the Laplace transformed BEM, the accuracy of teh numerical results is generally governed by the numerical treatment of the inverse Laplace transformation for the transformed solutions. Two types of numerical inverse Laplace transformation(NILT) formula, namely Krings & Waller's method and Hosono's method are applied to the 2-dimensional BEM analysis employing regularized boundary integral equations. It is shown that there is a stability condition between the element size and the time discretization. The characteristics of two types of NILT methods are found out through 2-dimensional BEM analyses for the unsteady elastodynamic problems.
    Download PDF (965K)
  • Koichi KIMURA, Masaaki OKAMOTO, Kazuhiro TSUNOSE
    1999 Volume 42 Issue 4 Pages 515-520
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    In this study, the nonlinear Berger equation for large deflection problems of isotropic plates and the finite-difference method are used to obtain solutions for deformation in rectangular elastic plates with a cross-stiffener. Numerical solutions are presented in order to illustrate the influence of the stiffener on the center deflection in uniformly loaded rectangular plates, which are supported by two beams orthogonally intersecting at the center of the plate. The numerical procedure is simpler than the procedures based on the von Karman theory, and takes into account the continuity conditions related to particular loads more rigorously than tha variational methods, such as the Rayleigh-Ritz energy method and finite element method.
    Download PDF (713K)
  • Keiichiro TOHGO, Young-Tae CHO
    1999 Volume 42 Issue 4 Pages 521-529
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    In particle or short-fiber reinforced composites, cracking or debonding of the reinforcements is a significant damage mode because the damaged reinforcements lose load carrying capacity. This paper deals with a theory of the reinforcement damage in discontinuously-reinforced composites and its application. The composite with progressive cracking damage contains intact and cracked reinforcements in a matrix. To describe the load carrying capacity of the cracked reinforcement, the average stress of a broken ellipsoidal inhomogeneity in an infinite body which was proposed in the previous paper is introduced. An incremental constitutive relation of the composites with progressive cracking damage of the reinforcements has been developed based on Eshelby's equivalent inclusion method and Mori and Tanaka's mean field concept. This damage theory can describe not only cracking damage but also debonding damage of the reinforcements by modifying teh load carrying capacity of damaged reinforcements. Influence of the reinforcement damage on the stress-strain response and elastic stiffness of the composites is discussed. It is noted that tha full-debonding damage gives the lower limit of the stress-strain relation of the composite with progressive reinforcement damage.
    Download PDF (1091K)
  • Akira TODOROKI, Masahumi SASAI
    1999 Volume 42 Issue 4 Pages 530-536
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    A genetic algorithm is applied to obtain the optimal stacking sequences for maximization of the buckling load of composite cylinders. In the problems, three constraint stacking rules are implemented. The first is that the angle plies of laminates have to be balanced. The second is that more than four contiguous plies of the same fiber orientation are not allowed. The third is that the difference in fiber orientation between adjacent plies must not be more than 45 degrees. The difficulty of handling the combinatorial constraints in genetic optimizations is overcome by adoption of a new repair system. When a chromosome violating the stacking constraints is decoded to a stacking sequence, the new repair system operates. The new repair system does not alter genes of the chromosome but changes only the decoding rules to introduce the constraints. This is similar to recessive genes in biology. By using this new repair system, a chromosome of{222111000}is decoded to[90/90/90/45/90/-45/-45/0/45]s. The design reliability of the genetic algorithm with the new repair system is examined in detail by comparing the reliability with a conventional penalty method. As a result, the genetic algorithm with the new repair system is shown to provide higher design reliability.
    Download PDF (1010K)
  • Hirohisa KIMACHI, Hiroshi TANAKA, Keisuke TANAKA
    1999 Volume 42 Issue 4 Pages 537-545
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The boundary element method was used to determine the elastic stress distribution near the tip of a delamination crack in fiber-reinforced plastics(FRP). FRP composites were modeled by a two-dimensional laminated structure composed of isotropic matrix and orthotropic fiber. A straight crack parallel to the fiber direction is placed in the matrix and is subjected to mode I or II loading. The stress intensity factor and the energy release rate were calculated as a function of the crack length for the above inhomogeneous model, and compared with those for a homogeneous model. For large cracks, the energy release rate for the inhomogeneous model is equal to that obtained for the homogeneous model for both mode I and II loadings. For small cracks, the energy release rate is larger for the inhomogeneous model than for the homogeneous model. The transition condition from small to large cracks was defined for the cases of mode I and II. The characteristics of the elastic matrix stress distribution ahead of the crack tip for the inhomogeneous model were discussed in comparison with the solution for the homogeneous model.
    Download PDF (1238K)
  • Liang-Chi ZHANG, Hiroaki TANAKA
    1999 Volume 42 Issue 4 Pages 546-559
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    This paper aims to investigate some fundamental problems of mechanics and physics in the nano-indentation of silicon monocrystals with the aid of molecular dynamics analysis. The study showed that inelastic deformation of silicon monocrystals is solely caused by amorphous phase transformation. Dislocations do not appear and purely elastic deformation exists only in an extremely narrow regime. The onset of inelastic deformation can be predicted by a criterion considering either the octahedral or maximum shear stress. Due to phase transformation, the conatct area between indenter and specimen varies in a very complex manner. The study offers a new theory for the nano-indentation of monocrystalline silicon.
    Download PDF (2343K)
  • Yoshihisa SAKAIDA, Keisuke TANAKA
    1999 Volume 42 Issue 4 Pages 560-567
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The surface of bending specimens of silicon nitride is finished by the surface-grinding method or the face-grinding method. A disk-shaped or cup-shaped diamond wheel with the grit size of #200/230 is used for grinding. The feed direction of the grinding wheel is either parallel or perpendicular to the longitudinal direction of bending specimens. The grinding flaw size is estimated from the bending strength and the residual stress distribution near the ground surface. In the case of surfece-grinding, the depth of grinding flaws formed parallel to the feed direction ranges from 40 to 70 μm. This grinding flaw extends outside the compressive residual stress zone, so the stress shielding effect is small. The large flaw size reduces the fracture strength. On the other hand, the depth of flaws of face-ground specimens ranges from 10 to 30 μm. The fracture strength after face-grinding is higher than that of lapped specimens because the flaw lies in the compression zone. The face-grinding method is recommended to minimize machining costs because finer finishing is unnecessary after facegrinding.
    Download PDF (1216K)
  • Takahito GOSHIMA, Sotomi ISHIHARA, Nobuyasu YAMAUCHI, Takashi KOIZUMI
    1999 Volume 42 Issue 4 Pages 568-577
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    This paper deals with the mutual interference of multiple two-dimensional interface cracks in a surface coating layered material under thermal stresses due to rolling/sliding contact with heat input. Contact loading is simulated as a contact pressure load with both the normal and shear components having parabolic distribution. Attention here is focused on the energy release rate at the crack tips which provide a measure for quantifying the magnitude of interface crack growth. In the present crack analysis, the interface cracks are replaced by the distributed edge dislocations, and the crack face friction is negrected. The problem is reduced to simultaneous singular integral equations for dislocation densities. The integral equations can be solved numerically by considering the nature of the singularities at the crack tips. The numerical results of the energy release rate showing the effects of the mutual interference of a pair of interface cracks are given for some tribological material coatings on a steel substrate. The effects of the frictional coefficient, the heat input strength and the coating thickness upon the magnitude of the energy release rate and it's mutual interference are considered numerically.
    Download PDF (1226K)
  • Akihide SAIMOTO, Yasufumi IMAI, Fumitaka MOTOMURA
    1999 Volume 42 Issue 4 Pages 578-584
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The crack growing behavior in a brittle rectangular plate under transient thermal stress is studied. The transient thermal stress imposed to the rectangle here is that of due to a line heater such as an electric resistance wire which supposed to be perfectly contact to the surface of material. When the heater is placed on the symmetrical axis of the rectangle, the crack propagates just along the heating line, therefore, this situation can be used for dividing a thin rectangular plate into equal two pieces. Contrast to the symmetrical case, on the other hand, the warping of crack propagation path is observed when the heater is placed other than the symmetrical position. The main objective of the present study is to clarify the mechanism of crack path warping in the case of unsymmetrical cleaving through the crack propagation simulation. The simulated and the observed crack path show good agreement with each other and factors which make the crack path warp are understood.
    Download PDF (1018K)
  • Mitsugu TODO, Kiyoshi TAKAHASHI, P.-Y. BEN JAR, Philippe BEGUELIN
    1999 Volume 42 Issue 4 Pages 585-591
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    Toughening mechanisms of three types of rubber toughened poly(methyl methacrylate)(RT-PMMA) were investigated under mode I loading condition by optical and electron microscopies in conjunction with the quantitative evaluation of mode I fracture toughness. Polarizing optical microscopy clearly exhibited damage zone development ahead of a crack-tip in the RT-PMMA's. The three RT-PMMA's revealed different shapes of the damage zone. Transmission electron microscopy exhibited microcrazes generated in the equator of rubber particles within the damage zones. Extensive deformation of rubber particles corresponding to localized shear yielding of the PMMA matrix was also found in a region close to a propagating crack-tip. In addition, cavitation of rubber particles was observed in the vicinity of the crack. It is therefore understood that the toughening of the RT-PMMA's is due to energy dissipation caused by the microdamage formations such as microcrazing, matrix shear deformation and rubber particle cavitation ahead of the crack-tip.
    Download PDF (2383K)
  • Hideki SEKINE, Ali M. AFSAR
    1999 Volume 42 Issue 4 Pages 592-600
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    In this study, we analyze the composition profile of semi-infinite functionally graded materials(FGMs) with a view to improving the brittle fracture characteristics of these materials. First, a method is developed to calculate the stress intensity factor of an edge crack in semi-infinite homogeneous media with distributed eigenstrain under a far-field uniform applied load. The crack is represented by the distribution of edge dislocations, and a singular integral equation with a Cauchy-type kernel is obtained using the complex potential functions of the edge dislocations. Second, a useful approximation method is established to simulate the nonhomogeneity of semi-infinite FGMs by an equivalent eigenstrain. The stress intensity factor is calculated for this equivalent eigenstrain. Finally, the stress intensity factor of the original semi-infinite FGMs is obtained by principle of superposition. By equating the stress intensity factor to the intrinsic fracture toughness of the FGMs, the apparent fracture toughness is calculated for prescribed composition profiles of the semi-infinite FGMs. Conversely, the composition profiles of prescribed apparent fracture toughness are also determined.
    Download PDF (1089K)
  • Takeshi UCHIDA, Sho KUSUMOTO
    1999 Volume 42 Issue 4 Pages 601-609
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The authors conduct experiments on fracture toughness of several types of freshwater ice under test conditions. The effects of loading rate, test temperature and specimen dimensions on the fracture-toughness value of polycrystalline ice, such as columnar-grained ice and coarse-grained ice are examined in this study. The test conditions cover the ranges of loading rate KI=0.8∼1.0×104kPa√(m)/s, test temperature T=-5∼-50°C and specimen width b=25∼200mm. Furthermore, the characteristics of fracture morphology under the above-mentioned test conditions are indicated. In the high loading-rate range, the effects of loading rate and test temperature on the fracture toughness are negligible. In the low loading-rate range, these effects are clearly observed and a transition region is confirmed. A considerable effect of the specimen width on the fracture toughness is observed. The characteristics of the macroscopic fracture surface are clearly affected by the loading rate, test temperature and specimen dimensions.
    Download PDF (1571K)
  • Naoto HAGIWARA, Yves MEZIERE, Noritake OGUCHI, Mures ZAREA, Remy CHAMP ...
    1999 Volume 42 Issue 4 Pages 610-617
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    More than 80 fatigue tests under fluctuating internal pressure are carried out on line pipes with a gouge in a dent in the longitudinal direction to develop a systematic database of fatigue behavior of pipelines. Unpressurized pipe specimens of different grades, diameters and wall thicknesses are first dented and then gouged prior to fatigue tests. This study clarifies that fatigue life(Nf), is dependent on dent depth(d), gouge depth(t)and hoop-stress amplitude(⊿σ)according to a power law Nf=c(d/D)α(t/T)β(⊿σ/E)γ, where c, α, β and γ are coefficients, D is diameter, T is wall thickness and E is Young's modulus. No obvious effects due to defect length and mean hoop stress are detected on fatigue life.
    Download PDF (1371K)
  • Keisuke HAYABUSA, Hirotsugu INOUE, Kikuo KISHIMOTO, Toshikazu SHIBUYA
    1999 Volume 42 Issue 4 Pages 618-623
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    Thermoelastic stress analysis(TSA) is a technique for measuring stresses through temperature changes induced by the thermoelastic effect of elastic bodies. Unfortunately, TSA can only provide the sum of the principal stresses. In this paper, the stress separation problem to determine individual stress components from the sum of the principal stresses is considered. The problem is divided into two parts:(1)an inverse problem to estimate unknown boundary values from the sum of the principal stresses inside the body, and(2)a direct problem to determine the stress components inside the body based on the estimated boundary values. This two-step approach is formulated and solved by BEM. It is found that the combination of Tikhonov regularization with supplementary data and Hansen's L-curve method is effective for attaining an accurate result of stress separation.
    Download PDF (791K)
  • Satoru YONEYAMA, Kazuo OGAWA, Akihiro MISAWA, Masahisa TAKASHI
    1999 Volume 42 Issue 4 Pages 624-630
    Published: October 15, 1999
    Released: February 18, 2008
    JOURNALS FREE ACCESS
    The present work studies time-dependent stress fields around a moving crack tip in a viscoelastic strip and crack extension resistance. Photoviscoelastic technique is employed for the evaluation of the time-dependent stress state around a crack tip. For the fringe pattern analysis, a new technique using an elliptically polarized white light, which can determine isochromatic and isoclinic parameters simultaneously from a colored image obtained by a single acquisition, is applied. The time-dependent stress intensity factor K*I which is extended for linearly viscoelastic materials is evaluated using a method based on least-squares. The results show that the proposed crack extension resistance K*<IC> may be considered as a characteristic property of the material under monotonically increasing load.
    Download PDF (1228K)
feedback
Top