材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
41 巻 , 461 号
選択された号の論文の24件中1~24を表示しています
  • 村上 浩二
    1992 年 41 巻 461 号 p. 138-143
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 小玉 泰義
    1992 年 41 巻 461 号 p. 144-147
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Properties of the sound transit through wood have been investigated to estimate the moisture content (MC) of wood by the ultrasonic method. In this paper, velocities and damping of longitudinal and transverse waves were measured. The heartwood of Sugi (Cryptomeria japonica D. Don) and Hinoki [Chamaecyparis obtusa (S. and Z.) Endl.] were used in the MC range of the oven-dried to green conditions.
    The velocities of ultrasonic waves were reduced as the MC increased. The decrease in ultrasonic velocity per unit moisture content was larger for Hinoki than for Sugi. In the range of MC more than the fiber saturation point (FSP), the ultrasonic velocity was represented by a function of specific gravity. The wood species used were approximately equal in the decrease in velocity per unit specific gravity.
    A ratio of the velocity of transverse waves to that of the longitudinal waves tended to increase with increasing MC. In the case of Sugi, the ratio was approximately constant in the range of MC more than the FSP.
    Damping of ultrasonic waves increased with increasing MC at the FSP or above. Furthermore, the damping of longitudinal waves was larger than that of transverse waves.
  • 植田 直見, 井上 美知子, 増澤 文武
    1992 年 41 巻 461 号 p. 148-152
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    In the conventional polyethylene glycol (PEG) method for conservation of waterlogged wood, it becomes sometimes difficult for PEG to penetrate into wood, depending on wood species or the degree of deterioration, and the shrinkage (e.g., max. 20-30% in tangential direction) or warp of specimens occurs. In the present study, in order to maintain their dimension and mechanical strength, Akagashi (quercus acuta Thunb.) wood was treated with some cationic surfactants which are easily adsorbed on cellulose and thus lower surface tention of water. By the surfactant treatment it is expected that possible shrinkage accompanied by water evaporation can be reduced. The size of the specimens used were 3×3×1.5 (tangential×radial×longituainal in cm). They were soaked in a few percent of cationic surfactant solution, followed by immersion into PEG solution with gradual increase of its concentration. The variations of dimension and weight were monitored periodically. As the result it was found that the surfactant treatment allowed PEG to penetrate easily into waterlogged wood which is otherwise difficult to allow the conservation treatment. Furthermore, it was noticed that the shrinkage and change in shape could be minimized, and the dimensions were maintained without any significant change. In addition, by using the present treatment, one can expect that the penetration time in the PEG treatment will be shortened.
  • 吉原 浩, 太田 正光
    1992 年 41 巻 461 号 p. 153-159
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    An existing FEM program for elastic-plastic problems was converted to the one which can be accomodated to the change of stiffness matrix and the release of stress at fractured elements. With this program, the fracturing processes of two testing types of wood (spruce) were simulated; the standard JIS shearing test (JIS Z2114) and the standard JIS bending test (JIS Z2113). The results are summarized as follows.
    (1) The shearing strength obtained by the calculation was 90.6kgf/cm2. This value agreed with the actual testing data. The fracture initiated and propagated along the grains. This simulated result accorded well with the real fracturing process in the shearing test.
    (2) The bending strength obtained by the calculation was 1297kgf/cm2, which was larger than the actual value because the finite element mesh was rough and thus the scale factors for yielding were estimated as large values. The fracture initiated at the bottom of the specimen, grew to the neutral axis and turned its direction to the grain. This simulated result accorded well with the real fracturing process in the bending test.
  • 平井 信之, 鈴木 滋彦, 梶野 清
    1992 年 41 巻 461 号 p. 160-163
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    In this report, wood was decrystallized at 25°C, 40°C and 60°C by using a non-aqueous solvent, that is a dimethylsulfoxide-chloral mixure, and the relationship between the degree of crystallinity and the dynamic modulus of elasticity of the decrystallized wood was examined. The results obtained are summarized as follows.
    (1) Small changes in dimension, weight and density of wood were observed in the process of decrystallization.
    (2) The degree of crystallinity and the dynamic modulus of elasticity decreased with increasing treated day. Their decreasing rates were accelerated as the temperature at decrystllizing process was raised.
    (3) The apparent activation energy for the decrystallization was estimated roughly by the reaction kinetics. The values calculated from the decrease in the degree of crystallinity and in the modulus of elasticity were about 4-8kcal/mol. Since there is no difference between these two activation energies, it may be considered that the modulus of elasticity of the decrystallized wood is closely related to the degree of crystallinity of wood.
  • 祖父江 信夫, 岡安 繁
    1992 年 41 巻 461 号 p. 164-169
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effects of the continuous vibration of small amplitude on the dynamic viscoelasticity of wood were studied for seven kinds of species of softwood and hardwood. The free-free flexural vibration method of rectangular beams was used. The vibration test was made in a chamber in which the temperature and humidity was controlled at 20°C and 65% R.H.
    The vibration was continued for five hours by using a self running oscillation circuit which automatically regulated a resonance frequency of a vibration system. The resonance frequency ranged from 100 to 170Hz and the amplitude of the vibration was 0.14mm at the end of a specimen. The dynamic Young's modulus E' and the loss tangent tanδ were measured at each one hour interval at ten degrees of amplitude in the range from 0.015 to 0.40mm.
    The dynamic Young's modulus was not affected by the subjected continuous vibration. On the other hand, the loss tangent decreased until about one or two hours and approached gradually to a constant value as increase of the vibration time. After five hours, the loss tangent decreased by about 5 to 15%.
    The loss-tangent decreasing process was studied by using the rate process theory, and the qualitative trend of the experiments could be well explained.
  • 梶田 煕, 川井 秀一, 今村 祐嗣
    1992 年 41 巻 461 号 p. 170-175
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Low molecular-weight phenolic resin as impregnating resin (IPR, Mn=389) and high molecular-weight one (Mn=962) were mixed and sprayed on sugi (Cryptomeria japonica) particles, and 10mm thick single-layer particleboards (PBs) (SG=0.7) were produced. On the other hand, seraya (Shorea spp.) particles were treated with acetic anhydride to attain at a 16% weight gain by replacing hydroxyl units of wood components with acetyl ones. The acetylated, non-acetylated, and mixed (50:50 weight ratio) particles were pressed into low-density PBs with densities of 0.4 and 0.5g/cm3 using polymeric-type urethane resin adhesive. The specimens of these two kinds of PBs and untreated PBs were subjected to various accelerated aging treatments: a) 6-cycle ASTM D-1037 exposure, b) 6-cycle WCAMA exposure, c) cyclic boil-dry test, d) BS 5669 test, and e) cyclic soak-dry test. Thickness swelling (TS) and internal bond strength (IB) were measured after each step of each cycle. The TS after treatment a) was affected greatly by the addition of IPR or the acetylation treatment. After aging-exposure test a), the TS value of the PBs with only 5% IPR loading or the acetylated PBs was about a half of that of the control boards. The spring back was rarely observed for the treated PBs with 20% IPR loading after cyclic exposure tests of a), b), c), and d). The exposure test affecting most severely TS and IB retention of PBs was test a), followed by tests b), c), and d), in order.
  • 谷口 義昭, 西尾 茂
    1992 年 41 巻 461 号 p. 176-182
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The objective of this study is to clarify the practical features of the new wood drying method, which combines microwave heating and vaccum, by determining the drying time and the quality of dried wood. To measure the temperature of drying wood in a microwave electric field, a thermal sensor was developed and incorporated into the microwave heating-vaccum dryer. The woods were dried by controlling the wood temperature. Beech (Fagus crenata), spruce (Picea spp.) lumbers, and persimon (Diospyros Kaki) blocks curved roughly for golf club heads were dried by the proposed new method. The results obtained are summarized as follows;
    (1) The thermal sensor with the function of reflecting microwaves was improved so as to provide accurate measurements of wood temperature during heating in the microwave field.
    (2) By controlling the wood temperature in the new drying method, none of such defects as surface checking and honeycomb appeared in dried lumbers, and the drying time was remarkably shortened compared with the conventional kiln-drying.
    (3) The present microwave heating-vaccum drying method is suitable for variously shaped wood pieces besides lumbers with flat surfaces.
    (4) The relation expressed by V=exp(a+bT) existed between the drying rate V and the wood temperature T irrespective of wood species. The drying rate V was highest for sapwood of beech, intermediate for spruce and persimon, and lowest for the heartwood of beech. The value of b was highest for the sapwood of beech, intermediate for the heartwood of beech and persimon, and lowest for spruce.
    (5) The drying operation based on the wood temperature was effective to shorten the drying time and to prevent drying defects.
  • 田中 學
    1992 年 41 巻 461 号 p. 183-188
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Effects of grain size, microstructure and cold work on the internal friction were investigated using a commercial high-tensile strength steel HT 80.
    The internal friction increased with decreasing grain size in the heat-treated specimens for both ferrite-pearlite and sorbite structures, while it did not exhibit any detectable grain-size dependence in the cold worked and heat-treated (recrystallized) specimens. At small strain amplitudes, the internal friction was larger in the heat-treated specimens with ferrite-pearlite structure than those with sorbite structure, irrespective of grain size. But, the internal friction was larger in the latter specimens at larger strain amplitudes and at larger grain sizes. The internal friction of the high-tensile strength steel in this case was principally attributed to the magneto-mechanical hysteresis loss and the viscous flow at grain boundaries and ferrite-pearlite phase boundaries.
    The internal friction and the hardness increased with increasing amount of cold work. The increase of internal friction was larger at larger amounts of cold work and at larger strain amplitudes.
  • 多々 静夫, 青木 勝, 松田 健二, 上谷 保裕, 池野 進
    1992 年 41 巻 461 号 p. 189-194
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The accurate orientation of β' matrix was determined first by SEM-ECP, and then α phase which transformed from the β' matrix during lower temperature annealing was observed as an embossed form by a preferential deep etching method. The embossed α phase at (011) matrix plane could be divided into two groups in shape as triangles and bend bars. The center line of the triangular α phase was almost parallel to (200) band of SEM-ECP from β' matrix, and the sharp corner, at which the centerline was connected, had an angle about 70°. At (001) matrix plane, an embossed α phase also showed a triangular shape and a sharp corner of triangle, which connected with the center line, was embedded into β' matrix. From SEM-ECP, center line of triangular α phase at (001) matrix plane was parallel to (200) band of SEM-ECP too. At (111) matrix plane, it was clear that the α phase consisted of one pair of two α plates. Such a pair of α plates were frequently combined with other pairs and then the more complex form built up. Especially, at (001) matrix plane, a pyramid like shape which consisted of four pairs of α plates was observed.
  • 小川 俊夫, 戸田 稔
    1992 年 41 巻 461 号 p. 195-201
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    This study is concerned with the peel strength of laminated steel plates constituted of two steel plates and a plastic sheet. Sufficient bonding between steel plate and polypropylene is required for application of this material. In this paper, the effect of molecular weight of polypropylene on adhesion was mainly investigated on the laminated steel plate.
    Two steel plates were adhered with a polypropylene sheet by using a mixed adhesive which composed of a silane coupling agent and peroxide, and adhesion strength was determined by T-peel test. The fracture surface created by peeling was observed by scanning electron microscopy (SEM), and its elemental composition was determined by electron spectroscopy for chemical analysis (ESCA).
    The extent of deformation of peeled surface in the polypropylene side increased with peel strength. It was concluded by ESCA analysis that failure occured within the oxidized polypropylene layer, namely, by cohesive failure. T-peel strength became larger with increasing molecular weight of polypropylene. This result suggests that the peel strength depends on the force of drawing out of polymer chains.
  • 中村 雅彦, 辻井 清司
    1992 年 41 巻 461 号 p. 202-206
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The surface of ultrafine silica powder was modified with three kinds of normal alcohol having different chain length. A conformation of substituted alkyl group on the surface of powder was argued through the adsorbed density of alkyl groups and the molecular occupational area on the silica surface. The obstruction effect against adsorption of water molecules on the modified silica surface was explained on the basis of conformation difference of the substituted alkyl groups.
  • 広崎 尚登
    1992 年 41 巻 461 号 p. 207-211
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effect of the amount of added oxide on the gas-pressure sintering behavior of silicon nitride and high-temperature properties (strength and oxidation resistance) of the sintered materials were investigated. Si3N4 containing 0.5mol% (SN05) to 10% (SN10) of equimolar Y2O3-Nd2O3 was fired at 1900°C for 4h in 10MPa N2 gas. A small amount of the oxide (1mol%; SN1) was effective for densification as well as larger amounts of the oxide (6-10mol%). Composition analysis of the sintered specimens indicated that SN1 densified through a small amount of SiO2-rich liquid phase, whereas SN10 densified by a large amount of additive oxide-rich liquid phase. SN1 had higher strength than SN10 at higher temperatures because of its smaller amounts of glassy phase. SN1 also had an excellent oxidation resistance because the composition lied in the Si3N4-Si2N2O-Y2Si2O7 compatibility triangle, where Si2N2O and Y2Si2O7 were stable with regard to oxidation.
  • 井上 靖雄, 佐藤 幸雄, 柏谷 賢治
    1992 年 41 巻 461 号 p. 212-218
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The behavior of plastic deformation was analyzed in terms of the texture development under the running surface of Shinkansen line rails which differs depending on the accumulated service tonnage. The results were discussed in comparison with those of rolling contact fatigue tests.
    It was found that the texture development under the running surface of Shinkansen line rail was similar to that in the test-piece tested under the condition of slip ratio 0% and maximum Hertz pressure about 0.9GPa. A texture appeard with an increase in accumulated service tonnage. However, the X-ray half value breadth did not change. This proves that the examination of texture development is useful to detect the rolling contact fatigue damage.
  • 高亀 寿, 浅野 秀樹, 宮野 靖
    1992 年 41 巻 461 号 p. 219-224
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Plate type specimens were prepared by the injection molding of rubber modified plastics such as acrylonitrile-butadiene-styrene terpolymer (ABS resin) and acrylonitrile-acrylic elastmer-styrene terpolymer (AAS resin). With these specimens the effect of the orientation of rubber particles in these resins on their strength anisotropy was examined. It was found from the experimental results of strength anisotropy that spots with strong anisotropy of tensile strength inside the molding plate tended to show lower dart fall impact values. It was also found that the orientation showing high tensile strength at each measuring spot coincided nearly with the orientation giving the biggest cracks in the dart fall impact tests. An examination was also made on the relationship between the orientation of rubber particles and the anisotropy of the tensile strength, or the dart fall impact value. The results showed that the anisotropy of the tensile strength increased and the dart fall impact value decreased as the orientation of rubber particles increased. Further more, it became clear that the effect of the rubber particle orientation on the strength differed with the kind of resins and that the AAS resin was less affected by the orientation than the ABS resin.
  • 北川 正義, 邱 建輝, 西田 憲一
    1992 年 41 巻 461 号 p. 225-231
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to investigate a nonlinear constitutive equation of polymers at finite strain for polymer solids, tension, torsion and combined tension-torsion tests under constant strain rate, stress relaxation and creep have been conducted to provide experimental data required for constructing the equation. Although the stress response under strain paths with its reversal is very important to understand fatigue behavior, there has been few experiments for polymers. Hence, the effect of strain history on the constitutive equation still remains unclear. Furthermore. the constitutive equation still remains unclear. Furthermore, the pressure dependent behavior on the exact stress-strain curves has not been observed in spite of many experiments on the pressure dependence of elastic modulus and flow stress. In this paper, cyclic torsional tests under hydrostatic pressures of 1 to 2000kgf/cm2 were carried out to describe both pressure and cyclic dependent behavior for crystalline polymers of polyethylene (PE), polypropylene (PP) and polyoximethylene (POM). It has been shown that (1) the shape of the stress-strain curves is not significantly affected by applied pressures, (2) cyclic softening occurs for the materials tested, but the degree of softening is dependent on materials, (3) the stress responses under partly reversed cyclic loading are differnt from the ones expected from fully reversed cyclic loading and (4) the stress responses for POM and PP are very sensitive to strain history, while the current stress-strain curve for PE is little affected by the previous strain paths.
  • 古江 治美, 平野 一美
    1992 年 41 巻 461 号 p. 232-238
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to characterize the fatigue strength of various injection moulded thermoplastics, such as PA6, PA66, PES or PEEK, and short glass or short carbon fiber reinforced composites with those thermoplastics for matrix, fatigue tests were conducted under alternating plane bending stress at 20°C.
    The effects of the properties of matrices, the kind of reinforced fibers and the molecular or fiber orientation on the fatigue strength characteristics were investigated. The short fiber reinforcement of advanced thermoplastics was also discussed on the basis of the fractographic examinations.
  • 千田 豊満, 曽我部 雄次, 有光 隆, 一柳 雅則
    1992 年 41 巻 461 号 p. 239-245
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The fracture of a wire rope used in a travelling jig crane caused a serious accident. In order to examine the mechanism of breakage, the reduction of diameter at the fracture portion of the wire rope was measured and the number of fractured wires around the wire rope was counted. Furthermore the sectional appearance near fracture portion and the fracture surface of the wires were observed. The main conclusions obtained in this paper were as follows;
    (1) Friction among the wires of the wire rope core rope caused the wear of wires to reduce the sectional area of the wire rope. The wear extremely took place between outlayer of outer stand and the wire rope core (inner strand). The wear caused the reduction of sectional area and diameter of the wire rope.
    (2) The increase of the applied stress in the wire due to the reduction of sectional area causes the growth and propagation of fatigue cracks.
    (3) Usable limit for wire rope enacted by Japanese Labor Ministry for the structure of travelling crane is considered to be insufficient to use a wire rope core rope safely.
  • 塩沢 和章, 西野 精一, 水口 隆史, 吉川 竜一, 矢口 達也
    1992 年 41 巻 461 号 p. 246-252
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Nickel-foam reinforced aluminum alloy (NFRA) has recently attracted special interest as one of the metal matrix composites. Nickel-foam is easily integrated with aluminum alloy because of high porosity, and its specific surface area is large enough to improve the wetability and adhesion and to form a Ni-Al intermetallic compound which is helpful in improving wear resistance.
    The aim of this investigation is to clarify the fatigue behavior of this new material. Fatigue crack propagation behavior of NFRA was studied using compact tension specimens under a testing frequency of 10Hz in air and stress ratio of 0.05, 0.5 and 0.7. Three types of NFRA with Ni-form squeeze casted with AC8A aluminum alloy were prepared and were heat treated with T6 processing.
    Fatigue crack propagation rate of NFRA decreased significantly as compared with that of AC8A-T6 aluminum alloy for low values of ΔK. The crack propagation rate was affected by the shape and size of nickel-foam. Acceleration and retardation of propagation rate was observed around the Ni-skelton because of propagation along the Ni-foam/matrix interface and in Ni-foam. The mechanism of crack propagation for NFRA was indicated by the equation of da/dN=A(Kmax)αK)β, where A, α and β are constant.
  • 上野 明, 岸本 秀弘, 河本 洋
    1992 年 41 巻 461 号 p. 253-259
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to clarify the crack size effect on fatigue strength, static and cyclic fatigue tests on sintered Si3N4 with a small crack were carried out. The small semi-elliptical surface crack was introduced by Knoop indentation. The residual stress attributed to indentation was eliminated by removing the surface layer. The surface removal was about 7 times of the net depth of indentation. In order to compare strictly the fatigue life with that estimated from a long crack, fatigue speciments were cut out from CT specimen with which the crack propagation rate was measured. As the fatigue life under cyclic load (R=0.1, f=60Hz) was shorter than that under static load, it was clear that the effect of cyclic load existed. The fatigue life obtained in the present work was compared with the estimated life which was derived from crack propagation data of CT specimen. It was concluded that the fatigue life in the present work was longer than the estimated fatigue life. It was thought that the difference between these fatigue lives was attributed to the difference in crack propagation rate due to crack size. On the fracture surface, there was no debris nor wear mark which was a characteristic mark seen on the fatigue fracture surface of CT specimen. It was considered that the crack opening displacement of small semi-elliptical surface crack was too small (maximum C.O.D. was about 0.1μm) to put Si3N4-crystals between the crack surfaces.
  • 田中 芳雄, 朴 吉煥
    1992 年 41 巻 461 号 p. 260-266
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Two types of sliding contact between a hard indenter and a brittle material were presently adopted: one is a conventional type and the other a grinding type. A fraction of heat flowing into the material in the grinding type was theoretically shown to be described by a function of a Peclet number and to be almost the same as that in the conventional type under the normal grinding conditions.
    The critical indenter radius, Rc, which distinguishes the occurence of plastic deformation from the elastic cracking as the first damaging event in the material, was analyzed under the mechanical/thermal load conditions.
    Increase in Rc with an increase in sliding speed V was very high in Al2O3 because of low thermal diffusivity κ, high thermal conductivity K and high thermal constant ME/{π(1+ν)ρC} (where, α: coefficient of expansion, E: Young's modulus, ν: Poisson's ratio, ρ: density, C: specific heat). While a similar relation between Rc and V was also found in Si3N4, the increase in Rc with an increase in V was small in glass and SiC because of low K and high κ, respectively.
  • 木下 俊哉, 若林 徹, 久保 紘
    1992 年 41 巻 461 号 p. 267-273
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Increase in has been fracture toughness due to crack deflection has been evaluated by theoretical calculation assuming mixed mode fracture (mode I+mode II+mode III) for a deflecting crack under the stress condition of mode I. Decrease in energy release rate occuring by the crack deflection was estimated from the stress intensity factors (K values) of an elliptical crack subjected to the mixed loads of tensile and shear stress (mode I+mode II+mode III).
    The toughening effect was discussed on the volume fraction, aspect ratio, radius of rod-like grains in the bulk materials and Poisson's ratio of the bulk materials. The results obtained are as follows.
    (1) The fracture toughness increases, due to crack deflection, by an amount of 90% of the fracture toughness attained by the crack with no-deflection.
    (2) The contribution of aspect ratio to the fracture toughness is significant up to 5 in its aspect ratio, and becomes constant at about 10.
    (3) The contribution of volume fraction to the fracture toughness is significant up to 10 vol%.
    (4) The fracture toughness is almost constant irrespective of the radius of rod-like grains.
    (5) The increase of fracture toughness has a tendency of inversely proportional to Poison's ratio.
  • 藤村 尚, 西村 強, 木山 英郎
    1992 年 41 巻 461 号 p. 274-279
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to study the ground movement due to tunnelling at shallow depth, a series of laboratory model tests and numerical analyses were performed. On the basis of the results of the trap door experiments, the fundamental properties of rupture surface lines and the maximum ground surface subsidence were discussed.
    X-ray radiographs of the deformation of sand during the cave-in of a trap door, showed a discontinuous internal surface having low sand density. The slip-line fields calculated by using the Kötter's method showed the failure zone in the upper ground of a trap door model.
  • 中村 林二郎, 中村 宏
    1992 年 41 巻 461 号 p. 280-286
    発行日: 1992/02/15
    公開日: 2009/06/03
    ジャーナル フリー
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