材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
41 巻 , 464 号
選択された号の論文の39件中1~39を表示しています
  • 石川 誠, 竹内 信行, 石田 信伍, 若松 盈, 渡部 公士
    1992 年 41 巻 464 号 p. 547-551
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Oxidation behavior of sintered Si3N4 incorporated with Y2O3 and Al2O3 as sintering aids was studied at 1400°C for 15h in wet argon flow containing 0.6, 3.5, 12.2 or 38.1 vol% H2O. The oxidation reaction was followed every minute by the measurement of the evolved H2 and N2 using a quadrupole mass spectrometer.
    In every oxidation experiment, the N2 and H2 evolution rates took maxima at the onset of reaction and then gradually decreased with time, although very sharp peaks indicative of the explosion of bubbles in the oxide layer were observed in the cases of high water vapor contents. Oxidation kinetics bore a linear-parabolic relationship except for the case of 3.5 vol% H2O. In case of 0.6 vol% H2O, the weight gain was very low while the amounts of the evolved H2 and N2 were very large, suggesting the concurrent active oxidation accompanied with the weight loss.
  • 久米 道也, 田辺 芳雄, 谷畑 公昭, 宮本 欽生
    1992 年 41 巻 464 号 p. 552-556
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    A new nitriding process titanium furface using the self propagating high temperature synthesis has been developed. A titanium plate was embeded in or coated with the self combustion agent of Nb or Ti metal powders, and the agent was ignited in a pressurized nitrogen gas atmosphere of 2.5Mpa. The nitriding reaction propagated through the agent and the surface of titanium was rapidly nitrided by the strongly exothermic heat over 2000K. The hardness, corrosion resistance and tensile strength of the surface nitrided titanium obtained by this method were comparable or superior to those of the surface nitrided titanium obtained by the conventional gas nitriding process.
  • 柳 炳煥, 高橋 実, 鈴木 傑
    1992 年 41 巻 464 号 p. 557-560
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The fluidity of alumina slurry and the packing state of green sheets prepared by a doctor blade method were investigated with the variations of added organics, such as the ratio of binder to plasticizer, the degree of polymerization of binder (PVB), and the amount of organics in the alumina slurry. The homogeneous slurries were first prepared from alumina powder, organics, and solvent by ball milling. Then, the viscosity and relative viscosity of slurries and the relative density of green sheets were measured. The results are summarized as follows:
    (1) The viscosity of slurry was affected largely by the ratio of binder to plasticizer, the degree of polymerization of PVB, and the amount of organics.
    (2) The apparent hydrodynamic shape factor (α) of alumina particles calculated from Dougherty-Krieger equation was 6-8 in the slurry.
    (3) The packing density of alumina particles in the green sheet changed little with the variation of added organics.
  • 西川 直宏, 高 鉄, 小坂井 守, 西部 徹, 高津 學
    1992 年 41 巻 464 号 p. 561-566
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Thermal fatigue behavior of four kinds of alumina ceramics, having different fracture toughness/bending strength ratio, was investigated. After the testpieces pre-cracked by Knoop indentation were heated in a constant temperature, they were quenched in water, and their propagated crack lengths were measured. Since the heat transmission condition varied from natural convection to nucleant boiling in the range of this experimental temperature, the heat transfer coefficient was corrected before illustrating the (KImax/KIC)-V curve. The thermal fatigue behavior of each alumina ceramics was discussed quantitatively based on the fatigue parameters n and A, which were derived from the crack propagation rate equation V=A(KI/KIC)n. For the alumina ceramics in which transgranular fracture was mainly observed, the n values were hardly different but logA values decreased with increasing particle size. This indicated that the crack propagation rate became low. For those in which more larger particles or pores were observed, the logA values and the crack propagation rate were quite different. Those different behaviors on thermal fatigue may be explained by different propagation mechanisms at crack tips. The control of microstructure is important for thermally used ceramics, because the microstructure determines the crack propagation pass.
  • 大田 陸夫, 名越 良幸, 福永 二郎
    1992 年 41 巻 464 号 p. 567-572
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The thermal stability of gels in the B2O3-Na2O-Al2O3 system was evaluated by two methods; (1) observation of the change of amorphous region after heating up to 200-800°C at a heating rate of 1°C/min and keeping for 2h, and (2) determination of the crystallization temperature Tc from the DTA curve of gels with heating rate of 5°C/min and calculation of the ratio of Tc to the liquidus temperature Tl, Tc/Tl. After heating gels up to 800°C, the original gel region, which extends over a wide area including Al2O3, was reduced to only a small amorphous region near the Al2O3 rich area. The Tc/Tl ratio showed the highest value of more than 0.8 in the composition range B2O3=55-90mol% and Al2O3=0-20mol%, while it was less than 0.6 value in the Al2O3 rich composition area. The compositional dependence of Tc/Tl ratio was compared with the variation of the glass-forming region obtained from melt at various cooling rates Q in the range of logQ=-2 to 5. It was recognized that the gel region having a high Tc/Tl value corresponds to a stable glass region obtainable under slow cooling. It seems that some close relationship exists between the Tc/Tl of a gel and the critical cooling rate Q* for glass formation of a melt having the same composition.
  • 野上 正行
    1992 年 41 巻 464 号 p. 573-577
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    SiO2 and 1.4Na2O20.8ZrO277.8SiO2 glasses doped with small-sized CdS crystals were prepared by the sol-gel process. Gels synthesized by the hydrolysis of Si(OC2H5)4, Zr(OC3H7)4, NaOCH3 and Cd(CH3CO2)22H2O were heated at 500°C, and then allowed to react with H2S gas to form the glasses doped with hexagonal CdS microcrystals. The degradation of the glasses was investigated with respect to the oxidation of CdS crystals. CdS crystals were incompletely embedded in the porous silica glass with high specific surface area. When heated, CdS crystals were oxidized in air at temperatures from 300 to 500°C and disappeared from glass at temperatures from 500 to 700°C in nitrogen atmosphere. On the other hand, 1.4Na2O20.8ZrO277.8SiO2 gel shrank at lower temperatures, in which CdS crystals were embedded. CdS crystals doped in the glass were stable against oxidation even though heated 500°C in air.
  • 傅 杰, 尾坂 明義, 三浦 嘉也, 高田 潤, 難波 徳郎
    1992 年 41 巻 464 号 p. 578-582
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    New photochromic glasses in the system Al-Cd-O-F were obtained. When this type of glass was irradiated by darkening UV light having the wavelength near the absorption edge, a new absorption was induced almost over the whole visible region. The photo-induced absorption decayed very slowly accompanying luminescence, and its half fading time was remarkably shortenedd by heating. Infrared and 27Al MAS-NMR spectra indicated that both AlX4 tetrahedra and AlX6 octahedra (X=O, F) were present and the fraction of octahedra increased with the increasing fluorine content. On the basis of both the ESR spectra and the glass structure model, the color centers were proposed to be oxygen hole centers.
  • 轟 真市, 平尾 一之, 曽我 直弘
    1992 年 41 巻 464 号 p. 583-587
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fluorescence properties of Eu3+ ions doped in several oxide glasses were investigated using UV excitation and laser induced FLN (fluorescence line-narrowing) techniques. Inhomogenities of the sites of Eu3+ were evaluated from the width of the fluorescence peak of 5D07F0 transition, ΔνIH. Borate and germanate glasses in which the network forming ions can take two kinds of the coordination number depending on the amount of these ions, showed the ΔνIH values larger than those of silicate and borophosphate glasses. On the other hand, phosphate glasses composed of chain-like units showed the small ΔνIH value. Furthermore, the splitting of 5D07F1 transition peak was investigated by using FLN technique in order to compare the sites of Eu3+ ions which were excited by the same laser energy. The widths of splitting in the borate, germanate and phosphate glasses varied with alkaline content, whereas those in silicate and borophosphate glasses hardly changed. Such behaviors seem to be due to the compositional dependence of the condition of non-bridging oxygens which coordinate Eu3+ ions. From these results, it was concluded that the environments around the Eu3+ -sites in the silicate and borophosphate glasses are not influenced so much by the concentration of Na2O.
  • 橋口 正一, 閔 恩基, 吉川 信一, 金丸 文一, 小林 猛
    1992 年 41 巻 464 号 p. 588-592
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    We investigated the reactivity of YBa2Cu3Oy (YBCO) with electrooptic crystals, such as LiNbO3 (LN), LiTaO3 (LT), Sr0.75Ba0.25Nb2O6 (SBN), KTa0.65Nb0.35O3 (KTN), Ba2NaNb5O15 (BNN). The YBCO powder mixed with 5wt% electrooptic crystal was heated at 700°C for 8hr, 16hr or at 900°C for 8hr in air. The reactivity of LT, LN, KTN with YBCO was considerably high, and that of BNN was relativly low.
    The YBCO thin films were deposited on LN and BNN substrates through an RF magnetron sputtering method. The YBCO thin films on BNN were c-axes oriented with Tc(zero)=72.5K and c=11.70Å. The thickness of the reaction layer for BNN was one order of magnitude thinner than that for LN. From these results, the BNN single crystal was concluded to be suitable for an electrooptic substrate for YBCO thin film fabrication.
  • 田中 啓介, 松井 元康, 四方 良一, 西川 友三
    1992 年 41 巻 464 号 p. 593-599
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The X-ray diffraction method was used to measure the residual stress in composite ceramics of zirconia mixed with various volume fractions of alumina. The triaxial state of the residual stress in each phase was determined from the X-ray diffractions of Al2O3 (146) by Cu-Kα radiation and of ZrO2 (133) by Cr-Kα radiation. In as-sintered materials, the residual stress in the alumina phase was compression, and decreased linearly with the alumina volume fraction Vf. On the other hand, the tensile residual stress was observed in the zirconia phase, and increased linearly with Vf. Those residual stresses were due to the mismatch of the coefficient of thermal expansion. The theoretical prediction based on Eshelby's inclusion mechanics agreed well with the experimental results.
  • 伊達 秀文
    1992 年 41 巻 464 号 p. 600-606
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    When a cylindrical projectile is collided normally with a target at high velocity, plastic deformation and/or failure occur on both bodies. If the relative impact velocity between both bodies is not high, a sharrow crater appears on the impact face of the target and a mushrooming profile on the projectile after impact. However, when the relative velocity is very high and the deformation resistance of the projectile is much lower than that of the target, the deformation of the impact face of the projectile becomes large and the outer part of the face is separated from the target by bending moment. Therefore, it is considered that the deformation process at the impact face of projectile is complicated.
    In this study, a lead projectile of 11mm dia., which has lower deformation resistance than that of the target, was collided normally with a stainless or polycarbonate target, and the deformation process at the impact face of projectile was recorded by an image converter camera from the side and the front. Additionally, the process was also examined based on the profile of craters on both targets and the distribution of the ring cracks on the polycarbonate target. The following results were obtained.
    The region from the center to about 7mm dia. of the projectile during impact was loaded compressively, and the projectile material flowed radially in the region from about 7mm to 14mm dia. In the outer region from 14mm, the material of the projectile was bent and separated from the target. These results show that the impact face of the projectile during impact can be characterized by three different regions described above.
  • 方 蘇春, 今井 圭介, 尾中 晋, 三浦 精
    1992 年 41 巻 464 号 p. 607-611
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The purpose of this investigation was to elucidate the effect of grain boundaries on yield drop caused by short-range order in α-CuAl alloys. Bicrystals with Σ3 {111} boundaries (coherent twin boundaries) of Cu-3 at.% Al and Cu-9 at.% Al alloys were grown by the Bridgman method. Bicrystal and single crystal specimens with different orientations were cut from the bicrystals. Difference in deformation behavior at room temperature among the specimens were compared by tensile tests. When the grain boundaries in the bicrystal specimens were obstacles to the motion of dislocations on the primary slip planes, the yield drop observed in α-CuAl alloy single crystals vanished or diminished. Changes in flow stresses due to the Σ3 {111} boundaries were shown. The contribution of the Σ3 {111} boundaries to the strength of the alloys and its aluminum concentration dependence were discussed.
  • 北條 英光, 津田 健, 新井 和吉
    1992 年 41 巻 464 号 p. 612-617
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Slurry erosion was measured for three kinds of polymeric materials placed in the flowing fluid. The motion of particles around the specimen, which has an important effect on the damage behavior, was analytically calculated.
    The erosion rate changed remarkably at a certain point of erosion curve. At this point the mechanism of damage showed the transition from ductile type damage to brittle one. The erosion rate varied with the kind of materials.
    A power law relation held between the erosion rate and the impact particle velocity obtained from calculations, and the value of exponent varied with the mechanism of damage.
    The effects of vertical and horizontal components of the impact particle velocity on the erosion rate in each mechanism were discussed. In the brittle type damage, the erosion rate depended only on the vertical component of the impact particle velocity. On the other hand, in the ductile one, the erosion rate was influenced by both components of the impact particle velocity. Therefore, the impact particle angle where the erosion rate became the maximum varied with the erosion mechanism.
    In the case of the brittle type damage, the relation between the vertical component of impact particle velocity and the number of impact particles during the incubation period was similar to the S-N diagram in fatigue. A threshold value of the vertical component of impact particle velocity to cause the brittle type damage was also recognized.
  • 井上 久弘, 弓削 毅, 川口 格
    1992 年 41 巻 464 号 p. 618-623
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to clarify the cutting mechanism of FRP, the quality of cut surface finish of unidirectional glass fiber reinforced plastics was investigated by changing the direction of glass yarn against the cutting direction. Cutting was operated under two-dimensional dry cutting conditions. The cut surface finish state of glass yarn end was discussed by taking the cut plastic surface state without any glassfiber as a standard surface. The following results were obtained by changing the both rake angle and depth of cut:
    (1) The cut end states of glass yarn near the cut surface were classified into two modes with changing the direction of glass yarn, such as the hollow pit and the swollen proturberance (uncut glassfibers).
    (2) The maximum hollow pit depth was almost twenty times of the maximum swollen proturberance height on changing the direction of glass yarn.
    (3) The change in rake angle of cutting tool did not affect the surface finish state.
    (4) The surface finish state became worse with increasing the depth of cut.
  • 村田 一夫, 水谷 勝己, 田中 芳雄
    1992 年 41 巻 464 号 p. 624-630
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Residual stress of ground ceramics is presently being evaluated in relation to the type and magnitude of material removal made by abrasive grains. In the present study, grinding of structural ceramics (Al2O3, SiC, Si3N4, and ZrO2) was carried out under conventional conditions, and the data connected closely with the material removal, such as grinding force, specific energy, surface roughness, and residual stress, were obtained. The main results were as follows:
    (1) Plastic deformation causing the compressive residual stress was mainly generated by the burnishing action of grains. The effect of burnishing diminished with an increase in the magnitude of fracture during the material removal; the compressive residual stress was larger in the ceramics with higher bending strength but smaller in those with higher hardness under conventional grinding conditions, because fracture during the material removal is less in the former and more in the latter.
    (2) The depth of the compressive residual stress can be estimated from the plastic deformation zone obtained by the sphere indentation which gives an analogous effect to the burnishing action of grains. The depth may be calculated by (0.6-0.8)r1/3RzY2/3(E/H)2/5; r=average radius of grains, RzY=ten point average height of the ground surface in the direction perpendicular to the grinding direction, E=Young's modulus, H=Vickers hardness.
  • 椿野 晴繁, 濱本 充治, 園田 一徳, 野里 僚一
    1992 年 41 巻 464 号 p. 631-636
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The bending fracture behavior of ZrO2-3mol% Y2O3 (PSZ) containing 0 to 12wt% Al2O3 was studied with reference to the tetrogonal-to-monoclinic phase transformation by three-point bending test, XRD, SEM-EDS and dilatometry. PSZ fractured at the stress just over the elastic limit. In PSZ containing Al2O3, on the other hand, the plastic elongation and serration phenomena were clearly observed. The resulting fracture stress increased with the addition of Al2O3. The grain size and density were almost independent of the addition of Al2O3. The segregation of both Y2O3 and Al2O3 at grain boundaries was observed in PSZ containing Al2O3. The different fracture modes in PSZ containing Al2O3 could be attributed to this grain-boundary segregation phenomena.
  • 松村 隆, 高松 徹, 市川 昌弘, 今野 武志, 西島 敏
    1992 年 41 巻 464 号 p. 637-642
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fatigue crack growth tests under tension-tension loading were performed on center-notched specimens of a high strength steel HT60, and the statistical property of fatigue crack growth rate da/dN was studied by testing 36 specimens under the same condition. The fatigue crack length was measured automatically using the DC electrical potential method and a microcomputer. The experimental data were analyzed from the viewpoint of the composite variability model of the fatigue crack growth rate which had been proposed by the present authors. The model parameters were estimated by a new method proposed in this paper as well as by the one proposed previously. The result of data analysis was compared with the previous result of 2024-T3 Al alloy. When expressing C in the Paris equation da/dN=CK)m as C=C*gl where g and l correspond to inter-specimen variability and intra-specimen variability of C respectively, the coefficients of variation of g and l for HT60 were approximately of the same magnitude as those for 2024-T3 Al alloy. On the other hand, the correlation distance for intra-specimen variability was smaller for HT60 than for 2024-T3 Al alloy. When a straight line log(da/dN)=logCs+mslog(ΔK) was fitted to the data of each specimen, ms and logCs of each specimen followed normal distributions approximately and strong negative correlation was found between ms and logCs. This property was quite similar to that for 2024-T3 Al alloy.
  • 宮崎 則幸, 佐々木 享, 中垣 通彦, F.W. BRUST
    1992 年 41 巻 464 号 p. 643-647
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    A finite element method was applied to a generation phase simulation of creep crack growth. Experimental data on creep crack growth in a 1Cr-1Mo-1/4V steel compact tension specimen were numerically simulated using a node-release technique and the variations of various fracture mechanics parameters such as CTOA, J, C* and T* during creep crack growth were calculated. The path -dependencies of the integral parameters J, C* and T* were also obtained to examine whether or not they could characterize the stress field near the tip of a crack propagating under creep condition. The following conclusions were obtained from the present analysis.
    (1) The J integral shows strong path-dependency during creep crack growth, so that it does not characterize creep crack growth.
    (2) The C* integral shows path-dependency to some extent during creep crack growth even in the case of Norton type steady state creep law. Strictly speaking, we cannot use it as a fracture mechanics parameter characterizing creep crack growth. It is, however, useful from the practical viewpoint because it correlates well the rate of creep crack growth.
    (3) The T* integral shows good path-independency during creep crack growth. Therefore, it is a candidate for a fracture mechanics parameter characterizing creep crack growth.
  • 角屋 好邦, 後藤 徹, 金子 秀明, 佐近 淑郎
    1992 年 41 巻 464 号 p. 648-653
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to improve creep-fatigue life prediction technology based on the crack growth of 2¼Cr-Mo steel casting, an investigation was carried out to predict the cycle-to-failure of smooth specimens with the fatigue-crack-growth-rate data obtained with CT specimens, as well as to comprehend the crack growth behavior with fatigue tests and creep-fatigue tests.
    The results obtained are as follows:
    (1) The micro-crack-growth-rate property of the casting material can be evaluated with the growth-rate data obtained by the macro-crack-growth tests with CT specimens.
    (2) There is good correlation between the behavior of the main crack growth and the life ratio for the surface crack growth behavior. In addition, the crack initiates at a relatively early stage of N/Nf=0.15 and the most part of the life is occupied by crack growth.
    (3) The calculated growth curves of the micro-surface-cracks correspond comparatively well with the observed crack growth behavior. Thus, even when the crack propagation life is considered to govern the total life, the cycles-to-failure of the specimen level can be predicted accurately within a factor of 2.
  • 三谷 進
    1992 年 41 巻 464 号 p. 654-660
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Effect of nitrogen content has been investigated on hydrogen embrittlement of cold-rolled SUS 304 with the content 0.05%, 0.13% and 0.18%. The bend-test was employed for evaluating the hydrogen embrittlement and the number of bendings before failure was measured for H-free and H-changed specimens (N: H-free, NH: H-charged). The main results are as follows:
    (1) For specimens whose Vickers hardness was below HV400, the number of bendings before failure of H-charged specimens (NH) increased with increasing nitrogen content. This effect of nitrogen content was not observed in specimens with HV>400.
    (2) The ratio of hydrogen embrittlement [RH=(N-NH)/N] increased with increasing Vickers hardness. For specimens whose Vickers hardness was below HV400, the effect of nitrogen content was observed on the hydrogen embrittlement. The RH of 0.05%-N and 0.13%-N specimens were the same and were greater than the RH of specimens containing 0.18%N. For specimens whose Vickers hardness was in the vicinity of HV400, the RH of all kind of specimens were almost the same.
    (3) Factors of the hydrogen embrittlement were strain-induced α' and ε martensite. The ratio of hydrogen embrittlement increased with increasing α' and ε martensite. For specimens whose α' martensite content was less than 35%, the influence of ε martensite content was observed on the hydrogen embrittlement.
  • 鈴木 惠, 木田 外明, 伊藤 和英, 正木 康嗣
    1992 年 41 巻 464 号 p. 661-667
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effects of notch root radius and notch length on the tensile impact characteristics of Polycarbonate were investigated in this paper. The results obtained are as follows:
    (1) The maximum load per the real cross sectional area of test specimen was proportional to the minus one half power of notch root radius. The relation between the specific absorbed energy and the notch root radius was similar to that between the specific absorbed energy and temperature, and the small notch root radius corresponded to low temperature and the large one to high temperature.
    (2) The maximum load per cross section area decreased a little and the specific absorbed energy decreased with increase in relative notch length.
    (3) The dynamic energy release rate could be determined from the slope of straight line showing the relation between the absorbed energy and BWΦ, where B was the thickness, W was the width, and Φ was the geometrical factor. The dynamic stress intensity factor could be also determined.
    (4) It was observed that most of the absorbed energy was used to initiate the neckings and tear lines on the fractured surface when the notch root radius was large. The absorbed energy changed little even though the relative notch length changed.
  • 網島 貞男, 藤井 透, 大窪 和也, 松岡 寿浩
    1992 年 41 巻 464 号 p. 668-672
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper describes the effect of textural pitch on the static strength of the hole notched composite reinforced by plain woven glass cloth. In the test, the static strength under tensile load was measured. The notch factor was used to evaluate the strength of hole notched specimen. The notch factor is defined as the ratio of the strength of unnotched specimen to that of hole notched one. This paper proposes a prediction method for the notch factor in consideration of the textural pitch of woven cloth as reinforcement. To investigate the influence of textural pitch on the stress distribution, the FEM calculation was carried out with a simplified model.
    The following conclusions were obtained. The notch factor changed with the ratio of the textural pitch of cloth to the width of specimen (P/W), in spite of constant value of the ratio of the hole diameter to the width of it (D/W). When the P/W was large, the notch factor was small and the stress concentration factor calculated by FEM was also small. The difference in notch factor can be explained by that of stress concentration factor. It is concluded that the internal dimension of material (for example, textural pitch) affects the stress concentration and the notch factor. The notch factor is well predicted when the characteristic length ‘d0’ of Nuismer-Whitney's point stress criteria (PSC) is described as a power function of the P/W.
  • 網島 貞男, 藤井 透, 大窪 和也, 片山 雄士
    1992 年 41 巻 464 号 p. 673-679
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The uniaxial tension, pure torsion and tension-torsion biaxially combined static tests were carried out with thin walled cylindrical specimens having a hole. The ‘static notch factor’ was introduced to evaluate the strength of hole notched specimen. The static notch factor is defined as a ratio of the notch strength to the unnotched one. The stress distribution around a hole under biaxially combined load was calculated. The stress concentration was evaluated by the effective stress concentration factor (called the ESCF) in which a multi-axial stress state was considered. The effect of the biaxially loading condition on the static notch factor of hole notched composite was explained by ESCF.
    The present study gave the following conclusions. The static notch factor has a linear relation with cos(tan-1α), if the biaxially combined stress ratio is denoted as α which is defined as a ratio of two applied nominal stresses σap2ap6. By using this relation, the static notch factor under biaxially combined load can be empirically predicted by uniaxial tension and pure shear tests. The static notch factor decreased with increasing shear stress component in the applied load, because a small component of shear stress reduces the stress concentration. The static notch factor was analytically predict by means of the minimum strength model (MSM proposed by Tan) with a high accuracy under biaxially combined. This paper also shows that the parameter of the prediction model can be determined by uniaxial tension test.
  • 増田 雄市郎, 金井 研司, 古江 治美
    1992 年 41 巻 464 号 p. 680-686
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The deformation and the stress distribution of woven cloth reinforced laminates under tensile load were studied by FEM calculation and approximate calculation by the curved beam theory. Two boundary conditions were assumed in the analyses. One is a single layer condition and the other is a multilayer condition in which the surfaces of a laminate under consideration are fully constrained to normal displacement. The calculated results by the curved beam theory for the apparent modulus and the stress concentration factor in the longitudinal fiber bundle coincided with the results by FEM calculation.
    The elastic moduli of the constituent materials of roving glass cloth laminates were determined by direct measurements and estimation by surface strain distribution of single layer laminates.
    The calculated results on the elastic behavior and the static strength had good agreement with the experimental ones for the single layer laminates. For multilayer laminates, the predictions did not agree with the experimental results, suggesting that some delamination processes bring their properties more likely to the single layer laminates.
  • 日和 千秋, 馬場 昭洋, 中川 隆夫
    1992 年 41 巻 464 号 p. 687-693
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Strength of composites depends on the strength of fibers and interface. The fibers are subjected to shear stress due to the adhesive force of interface. Therefore, to obtain a strong composite, one needs to have strong interface. The interface strength is especially important in the case of short-fiber composites. But, as the matrix is a polymeric material, the strength of composites decreases with decreasing adhesive force of interface at high-temperatures. There are two ways to obtain the interface of high strength; one is chemical adhesion and the other is anchor effect. The former depends on temperature. On the other hand, when the surface of fiber is irregularly roughened, the strength of interface increases due to the anchor effect. But the fiber strength decreases by stress concentration with increasing surface roughness.
    In the present study, to improve the strength of short-fiber composites, a new composite was developed with fibers having expanded-ends. Before the experiments, the suitable shape and size of fiber-ends were calculated by using a two-dimensional elasto-plastic FEM. The results of calculation showed that the end shape was spherical with the diameter five times bigger than that of a fiber. Practically, the ends of fibers were formed into disk shape and they were inserted between the laminas of GFRP. The tensile strength of the new composite increased by about 30% at the transition temperature of the resin.
  • 元木 信弥, 福田 武人, 田中 基博
    1992 年 41 巻 464 号 p. 694-699
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The criterion for the progress of matrix cracks is investigated for glass/epoxy cross-ply laminates. A series of experiments is conducted to obtain the relation of the laminate stress and the number of transverse cracks in [0/90n]s (n=2, 3, 4) configurations. Using Hashin's theory for stress in an element of a laminate, the maximum normal stress in 90° layer in the load direction is found to be the criterion for the matrix cracking. Independently of the stacking configurations, the matrix cracking progresses when the above stress exceeds a threshold value.
  • 名合 聡, 崔 洛三, 高橋 清
    1992 年 41 巻 464 号 p. 700-706
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Effect of notch tip radius on fracture behavior of compact tension type specimens of sheet-molding-compound (SMC) composites was studied. Notch tip radii (ρ) were from 0.09mm to 2.1mm. Acoustic emission (AE) measurements and microscopic observations were carried out to examine damage formation procedure around the notch tip. Optical observations by a dye-penetration method exhibited that fracture patterns in the specimens of ρ≤0.56mm were quite different from those in case of ρ=2.1mm. For ρ≤0.56mm, a main-crack initiated at the notch tip and grew in parallel with generation of many sub-cracks surrounding the main-crack tip. For ρ=2.1mm, on the contrary, during main-crack growth, sub-cracks propagated in radial directions. With increasing notch tip radius, there were observed little increase in the maximum load, AE cumulative event counts and standard deviation of AE source locations. Strain energy at the maximum load slightly increased with increasing notch tip radius in a range 0.09mm≤ρ≤0.56mm. States of fiber strands at the notch tip affected parameters on strength more significantly than notch tip radii within ρ=2.1mm.
  • 鈴木 惠, 孫 峰, 諸橋 茂, 木田 外明
    1992 年 41 巻 464 号 p. 707-713
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Acoustic emission (AE) characteristics of smoothed and notched specimens were investigated for a plain woven carbon fabric composite. The failure behavior of the smoothed specimen under tensile loading was estimated by the failure modes, AE parameters, and the load-elongation curve of the notched specimen. The results obtained are as follows:
    (1) The AE cumulative event count and the total AE energy of the smoothed specimen were larger than those of the notched specimen due to the difference in load level.
    (2) The AE amplitude distribution showed that the debonding of fiber/matrix and transverse/longitudinal fibers was the dominant failure mode before final fracture and generated much more AE than the fiber breakage. The AE activity of the smoothed specimen was larger than that of the notched specimen.
    (3) The load at the broken point of log-log plot for the total AE energy and stress intensity factor corresponded to the initiation of fiber/matrix debonding. It also agreed with the occurrence of AE.
    (4) The load-elongation curves of the smoothed and notched specimens could be divided into three parts. It was found that the initiation of the above debonding in the smoothed specimen can be estimated by the ratio of the load at the broken point to the maximum load of the notched specimen.
  • 倪 慶清, 自念 榮一, 岩本 正治
    1992 年 41 巻 464 号 p. 714-720
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In this paper, the acoustic emission method was used for clarifying the fracture mechanism of carbon fiber chopped strand reinforced plastics with a center crack through the thinkness in tensile deformation. It was observed that the load vs. displacement curve could be divied into five regions, and the fracture mechanism was made clear by combining the behaviour of acoustic signals in each region with SEM observation. The generation of initial stable cracks was clearly shown in the relationship between stress intensity factor and acoustic cumulative energy and that between stress intensity factor and acoustic cumulative events. The development of stable cracks was noticed by the change in acoustic event count rate. There existed two peaks in amplitude distribution. A three dimensional amplitude distribution was made, which gave the detailed relationship between the acoustic amplitude and the failure process. From this distribution, the acoustic event count rate can be classified into two types with low and high amplitude events which have different characteristics of microfracture mechanisms. Furthermore, a model was proposed to explain the pulled-out failure of chopped strand tapes.
  • 河津 幸雄, 野口 健一
    1992 年 41 巻 464 号 p. 721-727
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    Perforation impact behavior of Carbon Fiber Reinforced Plastics (CFRP) laminates was studied by comparing it with those of glass fiber reinforced plastics, aramid fiber reinforced plastics and 7075-T6 aluminum alloy. Using “TORAYCA” carbon fibers, M40, T300, T700S, T800H and T1000 and two types of epoxy resins having different cure temperatures, the effects of specimen thickness, tensile strength of unidirectional (UD) laminates, tensile strain of matrix and degree of surface treatment of carbon fibers on the perforation impact behavior were examined.
    The results showed that the impact resistance, the value of maximum load or the total absorbed energy, of CFRP was proportional to the strength of UD laminates, and was independent of the tensile strain of matrix and fracture toughness (GIC and GIIC) of UD laminates. It was also found that due to the lower interfacial bonding the impact resistance of CFRP increased when the degree of surface treatment decreased.
  • 芳我 攻, 小山 秀夫, 川田 勝巳, 小川 和洋
    1992 年 41 巻 464 号 p. 728-733
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The hybrid material in this paper has been built up from many thin aluminum alloy and unidirectional CFRP layers. As a result of the different thermal expansion coefficients of aluminum alloy and CFRP layer, the residual thermal stresses are present after cooling down from the curing temperature to room temperature. Two methods were used to control the residual thermal stress. One is to cure the composite under tensile force applied to the CFRP layers only and the other is to apply a stress which produces small plastic strain in the aluminum layers to the laminate after molding. The second method was very simple and the residual stresses could be controlled more precisely than in the first method. Some experiments were carried out on the hybrid plates controlled and not controlled. The following results were obtained: The tensile yield stress of the controlled composites plate increased more than that of the uncontrolled plate. However, the compressive yield stress decreased. The ultimate strain and the inter laminer shear strength, decreased due to the operation of the residual stress control. Some acoustic emission inspection showed that much interfacial failure was produced between aluminum alloy and CFRP layers during the operation of the second method. It was estimated that this was the factor causing the decrease in inter laminar shear strength.
  • 芳我 攻, 小山 秀夫, 川田 勝巳, 小川 和洋
    1992 年 41 巻 464 号 p. 734-739
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In the previous report, two controlling methods for the residual stress of Al/CFRP laminated material were explained, and also the investigation were carried out how to change its static mechanical properties by these controls. In this report the relation between stress controls and fatigue characteristics are investigated. The effect of residual stress controls was conspicuously revealed, especially on the fatigue characteristics. The crack propagation rate was reduced with the decrease of residual stress in the aluminum layers. Under a certain magnitude of mean stress and stress amplitude, it was found that crack propagation in a test piece where residual stress in the aluminum layers was converted from tension to compression was completely stopped. Even if residual stress controls were not carried out, it was shown that this material is overwhelmingly surperior to monolithic aluminum alloy plates in fatigue resistance. From this fact, it was shown that CFRP in the hybrid materials has a function to prevent crack propagation in the aluminum layers.
  • 西谷 弘信, 野口 博司, 金 允海, 山口 照敬
    1992 年 41 巻 464 号 p. 740-745
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In this paper, rotating-bending fatigue tests for short carbon-fiber reinforced poly-ether-ether-ketone (CFRPEEK) were carried out to investigate the fatigue characteristics of plain and notched specimens at room temperature. The fatigue mechanism in the composite was clarified through successive surface observations using the plastic replica method. The results were compared with those of poly-ether-ether-ketone (PEEK). In the case of the PEEK, the fatigue crack growth rate was very high and the fatigue strength was very sensitive to a notch. In the case of the CFRPEEK, the fatigue crack growth rate was much lower than that of PEEK, and the fatigue strength was much more insensitive to a notch than that of PEEK. The fatigue crack initiated from near the fiber end, and propagated in the circumferential direction after it grew to some extent along the fiber.
  • 芳賀 裕, 四十宮 龍徳
    1992 年 41 巻 464 号 p. 746-750
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    The influence of annealing on the photoconductivity of the composite materials of zinc oxide dispersed in polymethylmethacrylate (ZnO/PMMA) has been investigated. As a result, it was revealed that the photoconductivity of ZnO/PMMA composites was remarkably enhanced by annealing. From the experimental results of temperature dependences of the dark current, the dark current-voltage characteristics, the light wavelength characteristics and the photocurrent-light intensity characteristics, the photoconductive mechanism of the annealed ZnO/PMMA composites was discussed.
  • 巨 東英, 武村 伸介, 井上 達雄
    1992 年 41 巻 464 号 p. 751-757
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In this paper, equations describing the changes in temperature and stresses accompanied with solidification was developed based on thermomechanics. The finite element scheme for stress analysis as well as the temperature distribution were formulated, where a unified inelastic constitutive relationship capable of describing both elastic-viscoplastic solid and viscous liquid was employed. Examples of numerical calculation of temperature affected by solidification and stresses were presented for some practical cases of centrifugal casting process.
  • 高橋 利夫
    1992 年 41 巻 464 号 p. 758-764
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    PSPC (Position Sensitive Proportional Counter) makes it possible to obtain one-dimentional diffraction profiles without mechanical scanning. In a linear-type PSPC, the obtained profiles need correcting, because the position factor influences the intensity of the diffracted X-ray beam and the counting rate at each position on PSPC. The distances from the specimen are not the same at the center and at the edge of the detector, and the intensity decreases at the edge because of radiation and absorption. The counting rate varies with the incident angle of the diffracted beam at each position on PSPC.
    The position factor fi at channel i of the multichannel-analyser is given by
    fi=cos4αi·exp{-μR(1/cosαi-1)}
    where R is the distance between the specimen and the center of PSPC, μ is the linear absorption coefficient and αi is the incident angle of the diffracted beam at channel i. The background profiles of silicagel powder were measured with CrKα and CuKα. The parameters of the model function were fitted to the profiles by the non-linear least squares method. The agreement between these parameters and the calculated values shows that the position factor can correct the measured profiles properly.
  • 川嶋 紘一郎, 伊藤 智啓, 小島 正友, 森田 哲也
    1992 年 41 巻 464 号 p. 765-769
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    A measurement system of transit time of ultrasonic waves propagating through the thickness of plates under plane-stress state was developed, which is an improvement of the zero-crossing method with a personal computer and a high resolution digital memory or oscilloscope.
    In this system, thirty pairs of the first and second echo profiles stored in a digital oscilloscope are averaged in a personal computer, and then the rising portion of the averaged wave profile is enlarged on a screen of the computer and fitted to a straight line. The transit time of the echo is determined by the ordinate of the cross point of the straight line and the zero line. This system can measure the transit time to an accuracy of 1ns for shear waves propagating through an aluminum specimen.
    The acoustoelastic constants of a 2017-T3 aluminum plate of which rolling direction was parallel to the uniaxial tensile direction were found as follows; the constant for initial anisotropy=6.5×10-3, the stress-birefrigent coefficient=-34×10-6MPa-1.
    Using these constants, the principal stress difference of the residual stress in an annulus which was shrink-fitted to a shaft was measured. The tangential and radial residual stress components were separated with the elastic solution of plane axisymmetric stress field. They were in good agreement with the analytical results.
  • 佐近 淑郎, 角屋 好邦, 伊達 新吾, 後藤 徹, 松田 徹, 杉田 雄二, 服部 健司
    1992 年 41 巻 464 号 p. 770-776
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to improve the accuracy of remaining life evaluation for high-temperature bolts of 12Cr-Mo-W-V steel in long-time use, creep tests on its notched specimens were carried out and non-destructive evaluation of creep damage for the bolt threads were investigated. Bending creep rupture tests were also made for the bolt threads used for a long-time. The results obtained are as follows:
    (1) A bending creep rupture test equipment was developed to obtain directly the creep life expenditure of bolts. Specimens were taken from a bolt used over a long period and bending creep tests were carried out using this equipment. The results showed that the creep life expenditure of this bolt was small.
    (2) The creep void observation, hardness, eddy current and X-ray diffraction methods were applied to creep damage evaluation. In these methods except for the eddy current method, a good correlation was confirmed between the detected values and creep life expenditure. The creep void observation is considered as the most suitable method from the viewpoint of evaluation accuracy and applicability to the bolt threads.
  • 三宅 司朗
    1992 年 41 巻 464 号 p. 777-783
    発行日: 1992/05/15
    公開日: 2009/06/03
    ジャーナル フリー
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