材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
34 巻 , 382 号
選択された号の論文の19件中1~19を表示しています
  • 作花 済夫
    1985 年 34 巻 382 号 p. 763-771
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 森田 真史, 糸満 盛憲, 笹田 直
    1985 年 34 巻 382 号 p. 772-778
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    Osteoporosis is such a desease that the bone volume decreases with aging. As the mechanism of osteoporosis, the following is accepted widely: the bone resorption exceeds relatively the bone formation owing to a decrease in bone metabolic activity. In the past, the present authors have analyzed theoretically the progressive rate of the osteoporosis generated in a cancellous bone, and have clarified that the dynamic change in bone volume density depends on the remodeling activity of bone as well as the structural characteristic of trabecular architecture.
    In order to confirm this theroy, an experimental study was carried out in this paper. Firstly, the real bone volume fraction was measured by using the upper end of the osteoporotic femur dissected from cadavers. Then the result was compared with the theroetical value. As a result, it was learned that the decreasing tendency of the density predicted by the theoretical equation was well in accordance with the actual one.
  • 上原 勝, 鈴木 邁
    1985 年 34 巻 382 号 p. 779-783
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to obtain the fundamental data for application and design of shape memory alloy (SMA), the changes in characteristics of shape memory effect (SME) and reversible shape memory effect (RSM) with deformation cycles were investigated for Ni-Ti alloy.
    Though the following each phenomenon had been reported previously, the quantitative results obtained in the present study are summarized as follows;
    (1) SME and RSM changed greatly at initial deformation cycles.
    (2) The degradation of SME and the appearance of RSM became progressively greater with increasing deformation.
    (3) The relation between the appearance of RSM and the degradation of SME against deformation cycles was linear. This relation indicates that 1% degradation of SME generates 1.56% of RSM.
    (4) By the utilization of SME and RSM, it seems possible to start the reciprocating movement by applying thermal cycles. But, in order to obtain the desirable movement, it is necessary to have more detailed knowledges about the changes of sample shape, the treatment of shape memory and deformation.
    (5) All the transformation temperatures (Ms and Mf are the start and finish temperatures of martensite transformation, and As and Af are those of reverse transformation) changed linearly with the degree of deformation. With increasing deformation, the values of Af and Ms increased, while As and Mf decreased. These results indicate that the thermal cycles with a large temperature difference are required to achieve the perfect reciprocating movement.
    This paper also suggests the notion for utilization of SMA, sharpe design and characteristic property of Ni-Ti alloy.
  • 内藤 正鄰, 台丸谷 政志, 劉 凱欣
    1985 年 34 巻 382 号 p. 784-789
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    The present paper deals with plastic wave propagation in a bar subjected to longitudinal impact. It has been shown in authors' previous papers that the existence of a strain plateau adjacent to the impact end of a bar can be predicted by Malvern's strain-rate dependent theory and its appearance requires a certain time which is governed by the strainrate dependence of material and the impact velocity at the impact end. In this paper, the theoretical prediction of the previous papers was verified experimentally. First, the strain distributions in a finite length bar and a semi-infinite bar were predicted and the difference between them was examined. Next, the plastic strain distribution was measured in a cylindrical specimen by subjecting it to a longitudinal compression impact with a stress bar which remains elastic during the test. The duration time of impact was also measured on the stress bar.
    The results obtained are summarized as follows:
    (1) The strain plateau in a finite length bar was less uniform and less broad than that in a semi-infinite bar.
    (2) The experimental results for the lead and copper specimens almost agreed with the theoretical predictions. Consequently, it may be verified that the formation of strain plateau is governed by the factors mentioned above.
  • 加地 秋好, 濱田 泰以, 前川 善一郎
    1985 年 34 巻 382 号 p. 790-795
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper deals with the fracture mode and failure growth of FRP bolted joints. The laminated composite used in this experiment was the chopped strand glass mat reinforced unsaturated polyester with a double lapped bolted joint. The failure propagation behavior of the specimen bearing a bolted joint was examined in terms of three typical modes: the net tension mode, the compression mode and the multiple mode. The relationship between those fracture modes and the characteristics of the load-extension diagram obtained in the tensile test was also discussed. The two-dimensional finite element analysis was used in order to calculate the initial stress distribution and displacement of the specimen under a plane stress state. The prediction of fracture mode by numerical approach using the finite element method agreed well with the experimental data. Therefore, it is concluded that the finite element method can be used in the design of FRP bolted joints.
  • 鷹合 徹也, 大藤 晃義
    1985 年 34 巻 382 号 p. 796-802
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effect of cold rolling, which set 20% to 40% area reduction along the crack propagation direction, on the Charpy impact properties of a medium strength aluminum alloy (5083) was established by utilizing instrumented Charpy impact tests at temperatures ranging from 77K to 473K for four kinds of specimens which were cut out from a rolled plate in the directions parallel and vertical to the rolling direction. A standard V-notch was formed on the rolled surface of two specimens and in the vertical direction on the remaining two specimens.
    In general, by cold rolling the absorbed energy decreased remarkably by about 30 to 60% as compared with that of the unrolled 5083-O specimen in the temperature range of 77K to 373K. It was found that the effect of cold rolling on the absorbed energy differed considerably depending upon the crack propagation direction. When the crack propagation direction was vertical to the rolled surface, an extraordinary increase of absorbed energy up to about 120% appeared at 77K as compared with that of the unrolled specimen. On the other hand, when the crack propagation direction was parallel to the rolled surface, the increase of absorbed energy was about 35 to 55% at 474K.
    It is assumed that this extraordinary increase of absorbed energy at 77K is due to the occurrence of laminated fracture which was promoted by cold rolling.
  • 三浦 健蔵, 熊田 誠
    1985 年 34 巻 382 号 p. 803-808
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fatigue crack propagation behavior and the corrosion inhibition effect of sodium nitrite inhibitior were investigated from the observation of fracture surface of Cr-Mo cast steel under superposed stress both in air and in fresh water containing NaNO2 at 80°C.
    Under zero-tention loading of single wave, the change of crack front profile, a/c (aspect ratio) and the relation between the crack growth rate, da/dN and stress intensity factor, ΔK were represented by the following equations.
    a/c=0.90-3.98×10-1(a/D), D: Diameter of specimen.
    da/dN=1.04×10-10K)4.06
    Beach mark spacings coincided well with the block of superposed waves, Zp, and they were affected by the stress ratio, m. The beach marks were observed clearly at m=0.3, but not m=0.4 nor 0.5. The change of crack front profile was classified into two types. One was that where the crack propagated with ac in a semi-circular or semi-elliptical form. The other was that where the crack propagated with a<c, and afterwards propagated in a semi-elliptical form. The initial cracks always propagated with a<c in fresh water containing NaNO2 at 80°C. The fracture patterns influenced by corrosion were observed at the initial crack propagation region.
  • 内田 仁, 小寺沢 啓司, 隅田 守員, 山田 巌
    1985 年 34 巻 382 号 p. 809-815
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    The stress corrosion cracking (SCC) of subzero treated 301 steel single crystal in boiling 42% MgCl2 solution at 416K was studied crystallographically with the aid of electron microscopy.
    The subzero martensite which has the same crystal structure as strain-induced martensite (ε, α') was formed preferentially along the primary slip plane in austenitic matrix. The SCC threshold stress obtained by the constant loading method increased markedly as a result of the increase of mechanical strength by martensitic transformation. However, the ratio of threshold stress to yield strength (0.2% off-set) in oil at 416K reduced to half in comparison with that before subzero treatment. The SCC specimen surface presented an appearance of general corrosion, which was caused by the active dissolution of subzero martensite. In this case, the crack initiated at the area where slip steps were apt to occur, and then propagated preferentially along the primary slip plane. Consequently, the fracture appearance was characterized by the plate-like pattern, which was closely related to the morphology of subzero martensite.
    The above results suggest that ε-martensite formed along {111}γ plane contributes to the susceptible path for hydrogen cracking.
  • 戸梶 惠郎, 安藤 善司, 水谷日 出雄
    1985 年 34 巻 382 号 p. 816-822
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fatigue tests under rotating bending and reversed torsion were conducted in air, distilled water and 3 percent saltwater, using smooth specimens of austenitic stainless steel, SUS304. The initiation, density and distribution, and growth behaviour of small fatigue cracks were examined based on the detailed observations, and the effect of aqueous environment on fatigue strength was evaluated.
    Under rotating bending, the fatigue life was larger in distilled water and 3 percent saltwater than in air in the high stress region, but the fatigue strength decreased with increasing aggressiveness of test environment in the low stress region. Under reversed torsion, on the other hand, the fatigue strength was higher in an aqueous environment than in air in the whole stress region. These results were strongly related to various behaviours of small fatigue cracks such as initiation, density and growth, and were explained in terms of both cooling and corrosion effects of aqueous corrosive environment.
  • 三浦 健蔵, 大井 利継, 田中 孝雄
    1985 年 34 巻 382 号 p. 823-829
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fatigue tests under superposed stress were carried out in air and in fresh water containing sodium nitrite inhibitor (NaNO2) at 80°C using a relatively large Cr-Mo cast steel specimen. The applicability of the equivalent frequency method (ELF method) and the range pair mean method (RPM method) was investigated. The modified Goodman's method (RPM method I) and Yamada's method (RPM method II) were used to evaluate the effect of mean stress on stress amplitude.
    The best estimation of fatigue life among those three methods was RPM method II. The ratio of the experimental life, N to the estimated life, Nes tended to become low at the high life side for all the three methods. However, when RPM method II was applied on the basis of the completely reversed (stress ratio R=-1) S-N curve, in which the values under the fatigue limit were corrected, N/Nes became within the range of 1/3≤N/Nes≤5. It was found that NaNO2 was effective in the prevention of corrosion fatigue. However, the experimental life in fresh water containing NaNO2 at 80°C became a little bit lower than that in air. The relation between Nes and the cumulative damage, D was represented as follow.
    Nes=C/D
    C=1.00 (in air)
    C=0.80 (in fresh water containing NaNO2 at 80°C)
  • 岡田 庸敬, 服部 修次, 武田 昌彦
    1985 年 34 巻 382 号 p. 830-835
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    Torsional corrosion fatigue tests were carried out on S35C carbon steel to clarify the influence of pH in the test solution which contains HCl+NaCl or NaOH+NaCl. The following conclusions were drawn:
    (1) The fatigue strength at 107 cycles showed a maximum at pH 4, and then increased monotonically with pH. It is considered that the pH value in the test solution, initially at pH 4, increased with test duration, and the site of crack initiation was changed from the cathode area to the bottom of the corrosion pits.
    (2) The fatigue strength in the solution of pH 4 and 7.7 was decreased with the addition of NaCl, but it did not affect at pH 1 and 13.7. It is because electrical conductivity is not changed at pH 1 and passive film is formed at pH 13.7.
    (3) The reduction of fatigue strength with NaCl concentration (>0.005 wt percent) was more remarkable at pH 7.7 than at pH 4. The critical concentration of NaCl, below which NaCl has no effect on fatigue strength, appeared to be 0.005 wt percent in both pH solutions.
  • 岡崎 正和, 服部 一郎, 池田 俊明, 小泉 堯
    1985 年 34 巻 382 号 p. 836-842
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    The low-cycle fatigue life of SUS304 stainless steel at elevated temperature was investigated for the cases that the slow-fast strain cycle was periodically (Type-I) or continuously (Type-II) introduced to the fast-fast strain cycling. It was found that the fatigue life in Type-I considerably deviated from that evaluated by the linear damage summation rule to the unconservative side. On the other hand, the linear damage summation rule could be approximately applied to the case of Type-II, whether the continuous slow-fast strain cycles were introduced before or after crack initiation. To discuss the above difference between Type-I and Type-II, the crack initiation and propagation behaviors were investigated. As the result, it became clear that the shorter crack initiation life and/or propagation one in Type-I, compared with those in Type-II, attributed to the shorter fatigue life in Type-I. Furthermore, the crack growth rate and fatigue life under the combined strain wave cycling were predicted by modifying the linear cumulative damage rule. It was shown that the predicted crack growth curve and fatigue life were comparatively well consistent with the experimental ones.
  • 大谷 隆一, 北村 隆行
    1985 年 34 巻 382 号 p. 843-849
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    The authors have reported that the fatigue crack propagation behavior at elevated temperatures can be classified into cycle dependent- and time dependent-types and that there exists an independent fracture mechanics law between the crack propagation rate and the J-integrals for each type. In this study, the fatigue life law for smooth specimens was derived by integrating the crack propagation law. They are formularized as follows;
    (1) cycle dependent fatigue, ΔWfmfNf=Df
    (2) time dependent fatigue, ΔWcmcNf=Dcto1-mc where ΔWf and ΔWc are strain energy parameters, Nf; number of cycles to failure, mf, mc and Df, Dc; constants, to; tension time (see Fig. 1). Here, it should be emphasized that ΔWf and ΔWc are functions of not only the plastic or the creep strain range but also the stress range, the maximum stress and the elastic strain range.
    The validity of the above fatigue life law was discussed using the elevated temperature fatigue test data of three alloys; 2¼Cr-1Mo steel in which the effect of strain waveform on the fatigue life is known to be small, 304 stainless steel which shows the life dependence on dynamic aging, and Inconel 718 which is one of the low ductility superalloys. As a result, the fatigue life was correlated well with ΔWf for the cycle dependent fatigue and with ΔWc for the time dependent fatigue for all the materials.
  • 金子 純久
    1985 年 34 巻 382 号 p. 850-852
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    Mechanical degradation of Polycarbonate (PC) has been studied by using a homomixer at room temperature. The degree of degradation was determined by measuring the number-average chain length at various stages of mechanical degradation. It was found that the rate constant of mechanical degradation (ks) decreased with the degree of polymerization of PC at the initial stage of degradation. From the effect of Dimethylformamide (DMF) solvent on the degradation of PC, the maximum rate was obtained at 60%.
  • 金子 純久
    1985 年 34 巻 382 号 p. 853-856
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    Mechanical degradation of Polyvinylchloride (PVC) has been studied kinetically by using a vibration ball mill under one atmospheric pressure at room temperature.
    The degree of degradation was determined by the number-average chain length at various stages of mechanical degradation. The extent of degradation was represented by the rate constant of degradation (ks) and the final average chain length (P).
    The mechanical degradation of polycarbonate (PC) was also carried out at the same condition. In order to know the interaction between PVC and PC during mechanical degradation by a vibration ball mill, the mixtures of PVC and PC with various mixing ratios were also degraded with a vibration ball mill.
    ks of PVC in the presence of PC increased with increasing amount of PVC, while ks of PC decreased with increasing amount of PVC.
    These results were used to discuss the mechanical degradation behavior of polymer in a vibration ball mill.
  • 江原 昭次, 柳谷 俊, 寺田 孚
    1985 年 34 巻 382 号 p. 857-863
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    Thermal expansions of 11 dry rocks were investigated. These rocks were subjected to slow cyclic temperature change (0.5K/min) between 110K and 300K. They were divided into 2 groups according to their thermal expension behavior; existence of a hysteresis in the thermal expansion and a residual strain after the thermal cycling. (1) Nongranitic rocks (sedimentary and volcanic rocks) showed neither residual strain nor hysteresis. (2) Granitic rocks and Akiyoshi marble showed the residual strain and the hysteresis. Thermal expansion coefficient of the marble was negative at almost all temperatures. The difference in the thermal expansion between these groups was explained by the thermal cracking and the cracks in the rocks. Thermal cracking which is the cause of the residual strain can be produced by the mismatch of thermal expansion among the mineral grains. Cracks are responsible for the hysteresis by frictional sliding at crack surfaces and partial crushing of asperities. Decreasing temperature cannot provide the local strain sufficient to produce the cracking in the nongranitic rocks which consist of small grains and glassy matrix. On the contrary, the granitic rocks contain large grains and a large amont of quartz that shows larger expansion than other minerals. Akiyoshi marble is the aggregation of polycrystalline calcite that expands anisotropically. Themal cracking is therefore produced in these rocks during the first cooling stage.
  • 江原 昭次, 柳谷 俊, 寺田 孚
    1985 年 34 巻 382 号 p. 864-870
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    Thermal expansions of several saturated rocks were measured under a cyclic temperature change between 110K and 300K at a slow rate. The following changes due to water saturation were observed in thermal expansion; suppression of thermal cracking, hysteresis in thermal expansion, and an increase within thermal expansion coefficient. These changes were explained by freezing of pore water within cracks and the difference in temperature between freezing and melting of pore water. When the ice forms in the crack pore of granitic rocks, it bonds the surfaces of each crack to impede crack extension. The residual strain and the temperature at which thermal cracking initiated, therefore, decreased in these rocks. The temperature difference between freezing and melting is probably caused by supercooled water and a capillary force acting on the pore water. The hysteresis therefore appeared in the thermal expansion of nongranitic rocks which showed no hysteresis in the dry condition. These rocks exhibited no residual strain in the wet condition as well as in the dry condition except for the tuff in which a large amount of residual strain was observed after the first cycle.
  • 熊谷 雅晴, 奥田 直樹
    1985 年 34 巻 382 号 p. 871-876
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
    Relationship between gas permeability and grain size of submerged arc welding (SAW) fluxes has been investigated to get information for the analysis of SAW process. SiO2-CaO-MgO glassy flux and SiO2-MnO porous flux were examined using a flux bed (50-mm-diameter and 50-mm-height) and nitrogen current to obtain the permeability by the D'Arcys' law.
    Firstly, an experimental equation which shows the relationship between the permeability and grain size was derived for the fluxes with a series of grain sizes ranging from 8×12 to 200×325 mesh. Secondly, it was shown that almost the same permeability as given by the above equation could be estimated for the glassy flux by changing the friction coefficient in the equation proposed previously by Shirai. Furthermore, the permeability of the above glassy flux with two-or four-grain size components was studied. By using the mean grain size obtained by considering the Kozeny-Carman condition, the estimation of permeability for these systems became possible with fair accuracy.
  • 北川 浩
    1985 年 34 巻 382 号 p. 877-883
    発行日: 1985/07/15
    公開日: 2009/06/03
    ジャーナル フリー
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