材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
37 巻 , 423 号
選択された号の論文の18件中1~18を表示しています
  • 西沢 紘一
    1988 年 37 巻 423 号 p. 1363-1371
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 管野 善則, 鈴木 正
    1988 年 37 巻 423 号 p. 1372-1375
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    The dissociation temperature of zircon was estimated to be above 1700°C by interpreting the change in standard Gibbs free energy for the formation of zircon from the oxide components ZrO2 and SiO2. Zircon dissociates into m-ZrO2 and SiO2 glass. A commercial zircon power produced by the purification of natural zircon sand dissociated at 1650 to 1700°C. On the basis of these results, it is claimed that some correction is needed in the phase diagram of ZrO2-SiO2 system.
  • 古郷 佐八郎, 荻野 春之助, 富永 敏文, 浅見 克敏
    1988 年 37 巻 423 号 p. 1376-1380
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    Static tension tests at room temperature to 500°C and Vickers hardness tests at room temperature to 700°C were performed on the as-cast and heat-treated materials of spheroidal graphite cast iron. The regression equation that could estimate the tensile strength from Vickers hardness at elevated-temperatures was calculated and investigated. The main results obtained are summarized as follows.
    The tensile strength at an elevated-temperature decreased with increasing temperature for both the as-cast and heat-treated materials. Vickers hardness decreased with increasing temperature, which was the same as the tensile strength, and it decreased more rapidly when the temperature was above 600°C. However, the effects of normalizing and austempering heat-treatment on the tensile strength and hardness were remarkably noticed. A straight line relationship was established between tensile strength (σB) and hardness (HV) for various materials in the temperature range from room to 500°C, and the tensile strength was calculated by the following regression equation.
    The regression equation of σB and HV; σB(MPa)=2.80+2.586HV(kgf/mm2)
  • 百武 秀, 萩尾 照俊
    1988 年 37 巻 423 号 p. 1381-1385
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    The strength of unplasticized polyvinyl chloride (PVC) pipes being used widely was investigated by several kinds of tests. The static strength of PVC pipes was determined in tension tests by using the dumbbell shape specimens and the ring shape specimens. In order to study the fatigue strength of PVC pipes, flexural fatigue tests by plane bending for the dumbbell shape specimens taken from the pipe and pulsating internal pressure tests for PVC pipes were carried out at different temperatures in the range of 5°C to 50°C. An apparatus has been designed and constructed which allows the determination of the strength of circumferential direction of the pipe subjected to internal pressure. The experiments showed that the static strength in the circumferential direction of PVC pipes was about 90% of that in the longitudinal direction. On the other hand, the fatigue strength in the circumferential direction determined by the pulsating internal pressure test for PVC pipes was much less than that in the longitudinal direction by the plane bending test for the dumbbell shape specimen. The experimental results mentioned above were discussed in terms of the effects of temperature and strain rate on the yield stress of PVC. The results were also used to construct the critical curves of fatigue strength for PVC pipes subjected to pulsating internal pressure in a wide temperature.
  • 麻薙 悦男, 岡林 郁夫, 市川 宣明
    1988 年 37 巻 423 号 p. 1386-1390
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    The purpose of this study is to provide an effective method for stabilization of mud and sludge by using the hardening material consisting of calcium sulfate, blast-furnace slag and portland cement.
    The results are summarized as follows:
    (1) The so-called two steps system is a sufficient way to stabilize mud and sludge, when a proper condition is chosen. Namely, the hardening material works effectively when it is used in the form of two kinds of admixture. One of the admixture contains mainly calcium sulfate and the other portland cement.
    (2) The blast-furnace slag treated with acid is used effectively as an activated admixture.
    These results are explained from the action of the hardning material and the chemical characteristics of soil. Also, some application examples of stabilization of bad smelling mud and sludge are given.
  • 北川 正義, 松谷 智彦
    1988 年 37 巻 423 号 p. 1391-1396
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    The linear theory of viscoelasticity has been well formulated and successfully used in the past. In comparison, however, nonlinear viscoelastic plastic behavior at finite strains is less understood because of several complexities characteristic of polymer solids. In order to construct a visco-elastic-plastic constitutive equation in polymer solids, systematic experiments should be planned to demonstrate the effects of time, temperature and pressure on their material properties. In this paper, compressive and torsional tests were performed using polyethylene (PE) specimens under the conditions of constant strain rate, abrupt change in strain rate, stress relaxation and creep to provide some experimental facts on the time dependence of stress-strain curves. The experimental results were compared with the numerical results based on a over-stress theory. It is shown that the over-stress theory well explains the stress-strain curves of PE in the case where the current strain is not below the previous strain and the theory may become a valid model to infer the nonlinear behavior not only at a uniaxial stress state, but also at a biaxial one.
  • 高橋 清久, 田村 優子, 羽根 泰広, 山本 武志
    1988 年 37 巻 423 号 p. 1397-1402
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    1, 3, 5-trichloro-1, 3, 5-tridimethylamino-cyclotriphosphazene obtained from hexachloro-cyclotriphosphazene was used as a curing agent for epoxy resins. Epoxy resins (EPIKOTE828 and 154) were precured at 120°C for 7 hours. EPIKOTE828 was postcured at 140°C for 4 hours; EPIKOTE154 was postcured at 140°C for 5 hours followed by 200°C for 30 minutes. Dynamic viscoelastic measurements and tensile tests were conducted on the cured epoxy resins. The results were compared with those of epoxy resins cured by aminophosphazenes and m-phenylene diamine2). Although the glass transition temperature (Tg) was relatively low, these epoxies exhibited higher Young's modulus (30°C-Tg) and higher elongation (around Tg) than the epoxies investigated in the preceding paper2). Besides, in the thermo-gravimetric analysis, the epoxies cured by the present curing agent showed higher weight remaining in the range of 500-700°C. These results suggest that trichloro-tridimethylamino-cyclotriphosphazene has peculiar potential as a curing agent of the epoxy resins which can be used for load-bearing and fire-resistant applications.
  • 芳我 攻, 木村 稔
    1988 年 37 巻 423 号 p. 1403-1409
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    Recently, a sort of super hybrid composite materials made of metal sheets and FRP sheets have attracted a special interest. This report discusses about the flexural properties of the hybrid composite plates in which twenty layers of Al sheets (alminum IN-30, 0.1mm thick) and unidirectional CFRP sheets (fiber volume content 60%, 0.12mm thick) were laminated alternately and symmetrically. The results obtained are summarized as follows: (1) Flexural failure always occurred in the tension side. The reason is assumed to be that the compressive failure mechanism of CFRP layers due to microbackling or shear of carbon fibers changes to the tensile one by the effect of Al sheets which divide the CFRP into many thin layers. (2) On the assumption that the non-linear stress-strain behavior of this hybrid is due to the elastic perfect plastic behavior of aluminum, the theoretical behavior was derived by using the composite beam theory. The results calculated almost agreed with the experimental ones except failure strength. (3) the flexural strength was estimated using the maximum strain criterion for the failure of CFRP lamina. The values estimated were much smaller than those measured. This result suggests that the ultimate strain of CFRP layer in the hybrid composite increases more than that of CFRP monolithic by the effect of Al layers mentioned in (1). (4) The change of repeating stress-strain behavior under a gradually increasing load condition could be simulated accurately. The residual stress after an arbitrary loading could be calculated with a good approximation.
  • 石川 皓一, 谷村 眞治, 福永 時雄
    1988 年 37 巻 423 号 p. 1410-1415
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    The influences of strain rate and temperature on the flow stress of 304N stainless steel (SUS 304N) were studied experimentally. The thin walled tubular specimens with short gage length were tested at various strain rates between 10-3-103sec-1 in torsion. The experiments were performed in the temperature range from 83K to 296K. In the region of strain less than 20%, where the amount of martensite was relatively little, the flow stress under isothermal conditions was evaluated from the tested data obtained under the adiabatic test conditions. The strain and temperature effects on the shear strength of 304N stainless steel were investigated on basis of the flow stress under isothermal conditions.
    In the region of strain less than 5%, the amount of martensite formed in the specimen during torsional deformation was little and the effect of the amount on the shear strength could be disregarded, regardless of strain rate and temperature. At high strain rates, the strain rate effect on the flow stress in the region of strain less than 20% became remarkable with an increase in strain. In the region of strain less than 5%, where the material is in nearly complete austenitic phase, the followings became clear. At the constant strain rate, the flow stress in shear increased almost linearly with decreasing temperature. The slope of the shear stress-temperature curve at a high strain rate became gentler than that at a low strain rate. As the temperature became lower, both of the flow stress-temperature curves at the high strain rate and at the low strain rate showed a tendency to get close to each other. But the both curves did not coincide with each other at 0K. The strain rate dependency of the extrapolated threshold stress τ of 304N stainless steel was pronounced.
  • 岡部 永年, 矢野 利行, 平田 英之, 村松 正光, 米屋 勝利
    1988 年 37 巻 423 号 p. 1416-1422
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    A new device for impact testing suitable for evaluating ceramic strength was developed and was used in the experiments to develope a unified method for estimating both fast fracture and fatigue strengths. The fracture strength was measured by making 3 point and 4 point impact bending tests for three kinds of sintered Si3N4 specimens. Weibull analysis was performed for all the strength data with our original idea by considering the both effects of applied stress pattern and specimen size. With introduction of the effective hold time teff and the effective volume Veff, the impact strength obtained by each test was expressed commonly as the delayed fracture strength by using the following formula.
    σf(Nf teff)nf=Dfm√ln(1-Pf)-1/Veff
    where nf is the strength decrement index, Df the strength constant and m the Weibull Modulus.
    This formula is applicable to the probabilistic estimation of impact strength of ceramics.
    On the other hand, the strain rate-dependence of impact strength could be estimated by the following formula derived from the above formula.
    σf1/(1+n){(1+n)EDfn}1/(1+n)m√ln(1-Pf)-1/Veff
    where n is the crack growth rate index (1/nf) and E Youngs modulus.
  • 金澤 健二, 佐藤 守夫, 木村 恵, 西島 敏
    1988 年 37 巻 423 号 p. 1423-1428
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fish-eye fracture is observed on the smooth specimens of carbon and low alloy steels fatigued under rotating bending at temperatures from 200 to 500°C. The mechanism of the fish-eye fracture and the effect of oxidation on high-cycle fatigue behavior were discussed here.
    In the relationship between σaB and Nf, where σa is the stress amplitude, σB the tensile strength at each test temperature and Nf the number of cycles to failure, stepwise curves were obtained at 200 to 300°C and curves with an inflection point at above 400°C. At lower stress levels than the stress level of the stepwise or the inflection point, the fish-eye was observed at the fracture surface. At above 400°C, a region covered with thick oxide was observed independently of stress levels, shape of which looks like the cross section of a convex lens.
    A surface crack is not easy to initiate at elevated temperatures under low stress levels, as oxide at the specimen surface prevents dislocations from slipping off from the surface. During this period, the fish-eye fracture occurs from an inclusion in the interior of specimen. The stepwise curve comes from the difference in crack initiation site. At 400 and 500°C, the crack propagation process at the early stage is prolonged by oxide formed at the crack surface.
  • 久保 清, 八木 晃一, 金子 隆一, 梅澤 修
    1988 年 37 巻 423 号 p. 1429-1435
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    The combined creep-fatigue loading tests and the fatigue tests with tensile strain-hold wave form were conducted on 2 1/4Cr-1Mo steel, and the creep damage, φc, and the fatigue damage, φf, which were accumulated till rupture were calculated using the linear life fraction damage rule. The creep loading conditions of the both tests were within the transglanular fracture region on the creep fracture mode map obtained from the creep rupture tests. The specimens in the combined creep-fatigue loading tests were ruptured by an accumulation of either φc or φf, and the values of φc, and φf at fracture were 1.3 and 1.0, respectively. This φc vs. φf relation for 2 1/4Cr-1Mo steel showed the same trend as that for SUS304, SUS316 and 1Cr-Mo-V steels obtained from the combined creep-fatigue loading tests under the same creep damage mode condition, but the value of φc was dependent on testing materials. The φc-value seemed to be related with hardening or softening of materials due to fatigue loading.
    The φc vs. φf relation evaluated from the fatigue tests with tensile strain-hold wave form showed a different tendency to that evaluated from the combined creep-fatigue loading tests for 2 1/4Cr-1Mo steel. 1Cr-Mo-V steel showed the similar trend as 2 1/4Cr-1Mo steel, but the φc vs. φf relations obtained from both tests was the same for SUS316 steel. The effect of testing procedure on the φc vs. φf relation seemed to be connected with the sensitivity to oxidation of testing materials.
  • 内田 仁, 山田 学, 小寺澤 啓司
    1988 年 37 巻 423 号 p. 1436-1441
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    The susceptibility to stress corrosion cracking (SCC) of Zircaloy-2 in CH3OH solutions containing HCl at room temperature was examined fractographically.
    The weight loss due to intergranular corrosion during stress-free exposure reached the maximum value at a concentration of 0.4% HCl. There occurred a great deal of detrioration of mechanical properties after the exposure. The susceptibility to SCC under a constant load also increased in CH3OH/0.4% HCl solution. The fracture mode was changed from an intergranular into a cleavage-like fracture, and finally into a ductile fracture. A similar tendency was revealed by SCC tests under slow strain rates: At a lower crosshead speed of 1.67×10-1μm/s, all three modes of the intergranular, the cleavage-like, and the ductile fracture were observed.
    From the evidence mentioned above, a possible cracking mechanism was discussed.
  • 羽木 秀樹, 林 安徳
    1988 年 37 巻 423 号 p. 1442-1448
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    By using 0.1%, 0.3% and 0.6% carbon steels, the effect of microstructure on the formation of hydrogen-induced microcracks and the relation between the formation of microcracks and the acoustic emission (AE) caused by hydrogen charging have been studied.
    The results obtained are as follows:
    (1) Many microcracks were generated in ferrite grains in carbon steels with spheroidized structure, and at pearlite-ferrite interfaces and/or in pearlite in carbon steels with ferrite-pearlite structure. (2) The formation of microcracks was more remarkable in carbon steels with ferrite-pearlite structure than those with spheroidized structure. (3) The formation of microcracks could be detected as the signals of AE, and the total count of AE was proportional to the number of microcracks. (4) The addition of external stress to the specimen had no influence on the nucleation site of the microcracks nor on the number of microcracks generated by hydrogen charging. Therefore, the generation of microcracks is mainly governed by the internal stress due to dissolved and precipitated hydrogen atoms. (5) The addition of pre-strain to the specimen enhanced the formation of microcracks. (6) The microcracks are assumed to be formed by the following processes; (i) the appearance of large internal stress by hydrogen trapped at the interface, (ii) the generation of dislocations from the interface and the formation of dislocation walls, (iii) the nucleation of cracks along the dislocation walls by the large internal stress due to hydrogen trapped there.
  • 道廣 一利, 畑 浩二, 藤原 紀夫, 吉岡 尚也
    1988 年 37 巻 423 号 p. 1449-1455
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    Our previous experimental studies showed that the initial stress in rocks estimated from the Kaiser effect of acoustic emission is not necessarily the maximum stress that the specimen is subjected to, but is correlative to the residual strain in the specimen at the time of testing. The present investigation on the characteristics of the Kaiser effect in various rocks revealed that the initial stress estimated from the Kaiser effect tended to decrease with time after coring. Thus, the experiments to estimate the initial stress existing in a rock mass by means of the Kaiser effect, must be conducted as soon as possible after coring rock samples.
  • 吉成 元伸, 國藤 〓光
    1988 年 37 巻 423 号 p. 1456-1462
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    Recently, the number of applications of underground continuous soil-cement walls for ground retaining is increasing rapidly. However, the research in this field has not made almost anything clear yet and its theoretical explanation is lacking. The present research has been designed to learn the loading capacity characteristics of the soil cement section in a soil cement retaining wall. For this purpose, a full-scale model was constructed and a horizontal loading test was performed. The full-scale model was equivalent to a part of the soil cement retaining wall that could be obtained by cutting out the wall by 30cm of depth. The loading equipment was equipped with a loading plate that was fractionalized so that the load was distributed uniformly and the distortion in the loading direction was not restricted as far as possible.
    The experimental results revealed that the ultimate failure is the shear failure and that the model exhibits such properties as if an imaginary parabolic arch seems to be formed in the soil cement section. The shear strength, which is a dominant element of the loading capacity, ranged approximately from 1/2 to 1/3 of the compressive strength.
  • 栗田 政則, 小野 伸幸, 井原 郁夫, 矢田 敏夫
    1988 年 37 巻 423 号 p. 1463-1469
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
    Residual stress in ceramics induced by grinding plays an important role on the strength of ceramics. The X-ray method is effective in measuring residual stress in ceramics because it can nondestructively measure the residual stress in thin surface layer of 10 to 40μm of a specimen. In the measurement by X-ray diffraction, it is important to ascertain the reproducibility of the measured values from their standard deviation because the measurements by X-rays will involve variability caused by inherent counting statistics. To determine accurately the stress value in a sintered silicon carbide, an X-ray stress constant and elastic constants were determined by the Gaussian curve method which permits rapid and precise determination of stress. The standard deviations of these constants were calculated analytically to examine their reliability. (2.0.15) and (306) diffraction planes of silicon carbide were measured with CuKα radiation. For each diffraction plane, CuKα1, and Kα2 diffraction line profiles appear separately. Stress can be determined precisely by using the separate Kα1 single diffraction profile. The background correction in determining peak positions can be omitted because it does not affect the stress. The 95% confidence limits for the X-ray stress constants for the (2.0.15) and (306) planes were -971±48 and -1337±116MPa/deg, respectively. The limits for the X-ray Young's modulus of the (2.0.15) and (306) planes were 446±20 and 417±35GPa, and those for the Poisson's ratio were 0.165±0.013 and 0.157±0.016, respectively.
  • 川井 秀一, 佐々木 光
    1988 年 37 巻 423 号 p. 1470-1476
    発行日: 1988/12/15
    公開日: 2009/06/03
    ジャーナル フリー
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