材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
41 巻 , 463 号
選択された号の論文の21件中1~21を表示しています
  • 大久保 誠介, 西松 裕一, 何 昌栄, 秋 〓淵
    1992 年 41 巻 463 号 p. 403-409
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    Moisture has various effects on the behaviour of rocks. It is well known that the compressive strength decreases significantly with an increase of moisture content. Though many studies have been carried out concerning the effect of moisture, the influence on the time dependent behaviour is still open to discussion. It is very important to clarify its time dependence for analysing the long-term stability or durability of underground structures.
    In this study, six rocks were tested in uniaxial compression under four loading rates C=10-6, 10-5, 10-4 and 10-3/sec. With an increase of loading rate, it was found for all samples that the strength increased and the stress-strain curve in the post-failure region shifted to the right-hand side. The slope of the stress-strain curve, however, did not change meaningfully with loading rate. It should be noted that the increase of strength with loading rate did not depend on moisture content.
    The constitutive equation which is applicable to various time dependent behaviours was used to simulate the loading rate dependence under uniaxial compression tests. It was found that the calculated results gave a good approximation to the experimental results for all sample rocks.
  • 稲田 善紀, 国土 新彦
    1992 年 41 巻 463 号 p. 410-416
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to get the strength and deformation characteristics of Class II rocks which show a positive gradient in the post failure region of their stress-strain curves obtained by uniaxial compression tests, several methods have been tried and devised. One of them is a method of controlling the strain velocity and stress at the same time proposed by Nishimatsu et al.. However, this method needs a troublesome process to choose different gradients before and after failure. The present authors are proposing a method controlling the strain velocity before failure and then the stress and strain after failure.
    In this study, the strength and deformation characteristics of rocks at high and low temperatures obtained by our method using a trial machine were described and discussed. The results are useful as the basic information to store high and low temperature materials in caverns in rock mass. The results obtained are as follows:
    (1) The strengths of both Dry and Wet rocks used in this study, such as granite, andesite, sandstone and tuff, became lower with rising temperature and the strain at peak became larger.
    (2) The returning gradient of Class II rocks in the post failure region of the stress-strain curve at high temperature became lower with rising temperature, while it was a gentle change in Class I rocks.
    (3) The strength of rocks at low temperature became higher with falling temperature, and the strain at peak became smaller. On the other hand, the strength of wet tuff became higher, and the strain at peak became larger.
    (4) The returning gradient of Class II rocks in the post failure region at the stress-strain curve at low temperature became larger with falling temperature, while it was a steep change in Class I rocks. On the other hand, the gradient of wet tuff became gentle with falling temperature.
  • 木山 英郎, 藤村 尚, 西村 強, 池添 保雄
    1992 年 41 巻 463 号 p. 417-423
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    Active mobilization of bearing capacity of surrounding rock mass characterizes the NATM concept of supporting. However, no quantitative expression of this bearing capacity has been recognized yet. In the present paper, “a support load of surrounding rock mass”, “a support load of lining” and “the total support load of a tunnel” for a two-dimensional elastic circular tunnel were quantitatively evaluated by using a common index, support-stiffness, which is defined as the relative stiffness of each support to the original stiffness of the rock removed from the opening.
    By advancing the above analysis, the procedure to construct theoretically the bearing characteristic curve of elastic rock mass in tunnelling was discussed rationally. By applying the principles of this procedure to general rock mass with non-linear stress-strain property, various bearing characteristic curves were obtained from elastic type to elasto-plastic type, Fenner-Pacher type, or catastrophic type, depending on the initial earth pressure level related to the strength of the rock mass.
  • 谷本 親伯, 吉岡 尚也
    1992 年 41 巻 463 号 p. 424-429
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    Convergence monitoring can be easily carried out during construction and provides serial information on final deformation of tunnel wall, support load, development of the inelastic zone, etc. The authors estimated the width of the inelastic zone from the results of convergence measurements which had been carried out in sedimentary rocks, and clarified the relationship between competence factor and deformation rate. It was concluded that the allowable limit of deformation in tunneling (ΔD/D) must not be beyond 2%.
  • 山田 雅行, 白旗 秀紀, 佐々 宏一
    1992 年 41 巻 463 号 p. 430-436
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    In the crosshole seismic tomography, sources and receivers are placed in two parallel boreholes. For this source-receiver geometry, it has been clarified in the previous paper that the layer perpendicular to the holes can be detected quite well, but one parallel to the holes is hardly reconstructed. In this study, both the detectability of inclined layers and the relation between inclined angle of the layer and observation pattern were investigated, and an effective method to detect inclined layers was proposed. The coordinates of tomographic analysis were rotated so as to coinside with the angle of inclined layers, and the accuracy of reconstructed image was discussed. It was clarified that the detectable angle of inclined layers was closely connected with the angle of seismic rays.
  • 菅野 強
    1992 年 41 巻 463 号 p. 437-443
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to improve the reliability of electrical prospecting methods, it is necessary to measure voltage more sensitively so as to reflect target inhomogeneity in complex field conditions, to design more effective solid resistivity array combinations and patterns, or to develop additional new tomographic information under more restricted practical conditions, based on applicable electrical methods.
    In this study, a differential sensitivity distribution technique was newly developed and the computerized resistivity image section of the earth or material interior structure was constructed to examine the effectiveness of the new method. It was found that the pure differential sensitivity and the extended differential sensitivity distribution theorems could give very useful information and knowledge to improve the reliability of the conventional electrical tomography image reconstruction.
  • 南 宏和, 豊田 宏, 呉 鶯
    1992 年 41 巻 463 号 p. 445-450
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    Coated plain-weave fabrics are used as a membrane material of membrane structures including architectural membrane structures such as clear span air-supported membrane structure, flexible containers and airships. Uni/biaxial extension properties of coated fabrics are vary important for the design of membrane structures. In the present paper, the authors first presented SEM photographs of the surface and cut section to understand the structure of this material. Then unidirectional tensile tests were done up to failure. The stress-strain curves showed nonlineality and anisotropy. Some discussion was done on these properties. Poisson's ratio showed extreme nonlinearity at the stress region up to 20% of the failure stress which is the design stress. Specimens used here were a PTFE-coated grass fiber fabric and a PVC-coated polyester fabric which are widely used in the field of architectural membrane structure.
  • 南 宏和, 瀬川 信哉
    1992 年 41 巻 463 号 p. 451-457
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    The membrane materials are generally in various states of biaxial deformation in membrane structures, and also have visco-elasticity in addition to the peculiar nonlinearity. The biaxial extension curves, therefore, should be measured under the experimental conditions of iterative extension and various tensile speeds. In this paper, the authors selected PTFE coated plain-weave glass fiber and PVC coated plain-weave polyester fiber fabrics as the specimens, and measured the uni/biaxial extension curves up to the design stress (assumed to be 20% of the uniaxial breaking stress) under the experimental conditions of iterative extension and two different tensile speeds. The nonlinearity, the slope, and the iteration time up to convergence of the extension curves were studied. The dependences of these factors on tensile speed were also discussed. The main result of discussions was that the slope of extension curves depended upon tensile speed.
  • 村上 澄男, 水野 衛
    1992 年 41 巻 463 号 p. 458-464
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    A constitutive equation of creep, swelling and damage under neutron irradiation applicable to multiaxial non-steady states of stress is developed. In the formulation of the constitutive equation, the creep under irradiation was divided into irradiation-affected thermal creep and irradiation-induced creep. Then the irradiation-affected thermal creep was formulated by extending the creep-hardening surface model to include the effects of neutron-irradiation and material damage. The Bailey-Norton creep law and Kachanov-Rabotnov creep-damage theory were employed. The effect of irradiation on thermal creep was described by expressing the material functions of the constitutive equation as functions of neutron flux φ and neutron fluence Φ. The constitutive equation of irradiation-induced creep was formulated by taking account of SIPA and CCG mechanisms and by representing the creep rate as a function of stress of order zero and one. Creep of 316 stainless steel under various conditions of irradiation and variable stress was analyzed in order to elucidate the validity and the utility of the proposed constitutive equation.
  • 笠森 正人, 大塚 猛, 新保 實, 宮野 靖
    1992 年 41 巻 463 号 p. 465-469
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper is concerned with the time and temperature dependences of the static flexural behavior in CFRP laminates consisting of high temperature epoxy matrix and satin woven carbon fibers. Dynamic viscoelastic tests for neat resin and three-point bending tests for CFRP laminates were carried out under various loading rates and temperatures. The results obtained are summarized as follows;
    (1) The mechanical behavior of epoxy resin used was remarkably dependent upon time and temperature even in the vicinity of room temperature that is sufficiently lower than the glass transition temperature Tg.
    (2) The static flexural strength of CFRP laminates was also remarkably dependent upon time and temperature over a wide range of temperature even below Tg.
    (3) The time and temperature dependences of the static flexural strength of CFRP laminates was dominated by the mechanical behavior of matrix resin.
  • 砂田 久吉
    1992 年 41 巻 463 号 p. 470-474
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    Commercially produced ferritic spheroidal graphite cast iron was used in this study. The materials tested were prepared in two ways, austempering and hot-rolling. The austempering was done either at 573K or at 673K by quenching into salt bath and holding for 5min or 2hr after austenitization at 1173K for 1hr. Finally the materials were hot rolled at temperatures ranging from 1173 to 1073K.
    Charpy impact tests were carried out using a V-notched small test specimen (5mm×5mm×55mm) in the temperature range of 77-430K. The results obtained are summarized as follows;
    (1) The austempering at 573K elevated the tensile strength and hardness in comparison with that at 673K, while it lowered the impact value.
    (2) Both the tensile strength and absorbed energy were lowered by the rolling, because the cracks coalesced easily as a result of the narrower spacing of graphites.
    (3) The transition temperature determined by a mean value of the upper and the lower energy absorbed can be written in this order: ferrite<upper bainite<lower bainite<rolled ferrite
    (4) The absorbed energy was correlated with the size of the plastic zone ahead of the notch.
  • 石山 新太郎, 衛藤 基邦
    1992 年 41 巻 463 号 p. 475-481
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fracture toughness tests were carried out on nuclear graphite, IG-110 and PGX, and the effects of width, ligament ratio of compact tension specimen and cross-head speed on fracture toughness were examined. Crack extension processes in graphite specimen were observed by acoustic emission technique and optical observation method. From the results, it is concluded that:
    (1) A knee-point on the electrical potential-load displacement curve indicates macro-cracking in compact tension specimens.
    (2) Cracking occurred in the middle part of the notched surface of compact tension specimen and extended from the middle to the surface of specimen.
    (3) The value of JIC was constant within the range of ligament ratio from 0.4 to 0.55.
    (4) The value of JIC was constant within the range of cross-head speed from 0.005mm/min to 0.05mm/min.
    (5) The value of JIC was constant when the specimen width was more than 10mm for PGX graphite and 20mm for IG-110 graphite, respectively. However, JIC decreased as the specimen width decreased below the above-mentioned values. It is considered that this phenomenon is due to the formation of process-zone at the crack front of CT specimen.
  • 安田 公一, 大沢 栄也, 松尾 陽太郎, 木村 脩七
    1992 年 41 巻 463 号 p. 482-487
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    Pressureless sintered TiO2 bodies were annealed to change their grain sizes from 10μm to 59μm. Microstructural observations of the specimens indicated that the spontaneous critical grain size of TiO2 was about 20μm, and the mean length of network of microcracks was about 1.5mm. The thermal expansion analysis indicated that the volume fraction of spontaneous microcracks was about 1.5×10-3. The grain size dependences of Young's modulus and fracture stress ensured the spontaneous microcracking. Fracture toughness KIC was measured by a chevron-notched beam method. KIC took a constant value below the critical grain size, but it was reduced to about 65% above the critical grain size. The reduction of KIC could be estimated quantitatively using the length and volume fraction of microcracks.
  • 林 國郎, 辻本 真司, 岡本 泰則, 西川 友三
    1992 年 41 巻 463 号 p. 488-494
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    The fracture toughness (KIC) on the major planes of single crystal silicon was measured by the controlled surface flaw (CSF) and indentation fracture (IF) methods at high temperatures. The KIC values obtained by the CSF method for the surface orientations {100}, {110}, {111} and {112} of silicon up to about 500°C decreased with increasing temperature. In the low temperature region, the linear decrease of KIC for {110}, {111}, and {112}, excepting for {100}, was explained on the basis of an elastic model. The KIC values for {100}, {110}, {111} and {112} planes of silicon increased rapidly over the temperatures of 500, 600, 700 and 800°C, respectively.
    It was found that the rapid KIC increase for those planes of silicon at the individual critical temperatures was attributable to extensive plastic yielding in the vicinity of the crack tips relating the Schmid factor and numbers of slip systems for each planes. The KIC values obtained by the IF method in the range from 400 to 600°C were larger than those obtained by the CSF method for all planes. The trend of increase in KIC values by the former method in the high temperature region agreed with that by the later method.
  • 上野 明, 岸本 秀弘, 河本 洋, 山中 洋一
    1992 年 41 巻 463 号 p. 495-501
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to investigate the effect of crack size on the crack propagation behavior of a sintered silicon nitride, crack propagation tests were conducted under cyclic loads and static load. Two different sizes of small surface semielliptical cracks were introduced by Knoop indentation. By polishing the surface layer, the residual stress caused by Knoop indentation was perfectly removed. The crack propagation rates of small cracks (350μm, 200μm) were slower than that of a long crack obtained with CT specimen. Analyzing the crack opening displacement (COD) of the 350μm crack, we could determine the quantity of the true stress intensity factor KItip·KItip was expressed as KItip=KImax-Ks, where Ks is a component of the stress intensity factor shielded by bridging effects. Furthermore, we found that the COD after cyclic loading was larger than that before cyclic loading. It is evident that the increase in COD after cyclic loading was originated from the reduction of bridging force with cyclic fretting at the bridging sites under cyclic loads. It was concluded that the reduction of bridging force made the KItip increase and increased KItip accelerated the crack propagation rate.
  • 小川 武史, 大矢 耕二, 戸梶 惠郎
    1992 年 41 巻 463 号 p. 502-508
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    The characteristics of fatigue crack growth were investigated in Ti-6Al-4V alloy with three kinds of microstructure prepared with different heat treatments. The effect of microstructure on the crack growth behavior was attributed to the development of crack tip shielding, primarily resulting from the role of the crack path morphology in inducing crack closure and crack deflection. Roughness induced crack closure played an important role on the near-threshold growth behavior at the load ratio of 0.05, but the growth rate data plotted in terms of effective stress intensity factor range ΔKeff (after allowing for closure) still exhibited the effect of microstructure. Fractographic observations were performed using a scanning electron microscope (SEM) with the aid of image processing, which enables the three dimensional observation using a stereo pair of SEM micrographs. The roughness was evaluated quantitatively by the ratio of the total area of the three dimensional fracture surface to its projected area. As the fracture surface roughness was taken into account in re-evaluating the crack growth characteristics, the effect of microstructure disappeared, indicating that the intrinsic crack growth resistance was the same for all microstructure. Thus, fracture surface roughness is a controlling parameter of the fatigue crack growth in Ti-6Al-4V alloy. Furthermore, the crack growth rate were compared with those of other structural materials such as steels, nodular cast iron and an aluminum alloy.
  • 長瀬 康男, 沢木 洋三, 吉田 始
    1992 年 41 巻 463 号 p. 509-515
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to evaluate the stress of a machine part subjected to variable stress amplitude, the density of fatigue slip bands produced on aluminum foil is proposed as a measure for this purpose. The fundamental characteristics of slip band formation were examined under both constant and variable amplitude stresses. It was found that the density of slip bands was dependent on both the stress amplitude and the number of stress cycles. The variation of stress amplitude hardly affected the increase of the slip bands in successive stress cycles, irrespectively of the variable mode of stress. The density of slip bands under variable loading, fs was well correlated with the equivalent stress, σeq=(ΣσαiNiNi)1/α, where σi, Ni and α are stress amplitude, the number of stress cycles at σi, and a material constant determined from an aluminum foil used, respectively. It is concluded that the equivalent stress can be evaluated by the density of slip bands produced on aluminum foil, using the relationship between fs and applied stress amplitude obtained under constant loading. The accuracy of measuring the equivalent stress was within 3%.
  • 久保内 昌敏, 津田 健, 本橋 征行, 北條 英光
    1992 年 41 巻 463 号 p. 516-522
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    Previously the present authors proposed the testing method of thermal shock resistance using a notched disk type specimen of brittle type epoxy resin and its evaluation method based on fracture mechanics. In order to examine their applicability, some practical epoxy resins for casting were tested in this study.
    For brittle alicyclic epoxy resin, irrespective of the cooling bath temperature, the nondimensional stress intensity factor calculated by the experimental results agreed well with that of theoretical estimation.
    In the case of mixed resin of bisphenol A epoxy having certain toughness and very brittle alicyclic epoxy, the critical temperature difference ΔTC was clearly recognized for all resin systems with various mixture ratios, and the resin with higher bisphenol A epoxy content showed higher thermal shock resistance. For the bisphenol A type epoxy resin with longer molecular chains (larger number of repeated units) indicated higher resistance. The analysis agreed well with the experiments for these both resin systems.
    For the epoxy resin modified with a low content of plasticizer, the same evaluation method of thermal shock resistance was found to be applicable. But over 20phr content, plastic flow occurred markedly, and so the critical temperature difference could not be obtained. For such cases, it is still possible to evaluate the thermal shock resistance by using a large size specimen.
  • 芳賀 裕, 四十宮 龍徳
    1992 年 41 巻 463 号 p. 523-527
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    The carrier mobilities and carrier transport mechanism of composite materials of TiO2 encapsulated in polymethylmethacrylate (C-PMMA-TiO2) were investigated by the Time-of-Flight (TOF) method. As the result, the drift mobility of C-PMMA-TiO2 increased as compared with that of TiO2, and its value showed a tendency to increase with an increase of encapsulating ratio. The increase of drift mobility of electrons became larger than that of holes. Since the dispersion parameter α showed the temperature dependence, it was considered that the mechanism of carrier transport in C-PMMA-TiO2 was the limited transport of carriers captured by the localized levels existing in an exponential distribution. Furthermore, it was found that the density of the localized level increased with increasing encapsulating ratio.
  • 有馬 孝禮, 早村 俊二, 丸山 則義
    1992 年 41 巻 463 号 p. 528-534
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
    More efficient use of construction adhesives as structural fasteners requires detailed knowledge on the behavior of adhesive joints between load-bearing building components under actual service conditions. As the strength of adhesive joint depends on the shear strength of wood as well as the strengths of adhesive and its bonded surfaces, both the strength of adhesive joint and the percentage of wood failure are provided as the test indicators. In this report, the relationship between the shear strength of adhesive joint and the percentage of wood failure was derived from the strength of wood and adhesive. The proposed schematic representation showing the distributions, of shear strength and of wood failure can be a powerful tool for evaluating how the strength changes with time or under accelerated aging, or which of the degrading factors is the major one. Based on observation of the shear test and the appearance of the fractured adhesive, interpretation of the results and recognition of the estimates under aging will become easier. A recent inspection of adhesive joints for glue-laminated timber after 6 years outdoor exposures shows that the rate of change in joint strength is attributable to the wood degradation and no adhesive failure occurs.
  • 坪井 学
    1992 年 41 巻 463 号 p. 535-539
    発行日: 1992/04/15
    公開日: 2009/06/03
    ジャーナル フリー
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