材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
40 巻 , 449 号
選択された号の論文の17件中1~17を表示しています
  • 冨田 恵之
    1991 年 40 巻 449 号 p. 133-143
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 巨 東英, 大鹿 容祐, 井上 達雄
    1991 年 40 巻 449 号 p. 144-150
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The heat conduction equation was formulated for the solidification problem of centrifugal casting process, in which the air/metal free boundary was considered. A finite element scheme was set up from the Galerkin equations. As the amount of liquid metal increased, the heat capacity of the expanding elements was altered. Heat generation due to the liberation of latent heat was also considered following the rate of change of solid fraction in the element.
    The scheme was applied to two types of centrifugal casting problems. The temperature distribution and solidification front were analyzed and compared with the experimental results.
  • 方 蘇春, 今井 圭介, 尾中 晋, 三浦 精
    1991 年 40 巻 449 号 p. 151-157
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Copper Σ3{111} and Σ9{221} symmetrical ‹110› tilt bicrystals and their component single crystals were tensile tested at room temperature. By the stress-strain curves obtained and the observation of slip lines, the effect of grain boundary on plastic deformation was discussed. The effect of grain boundary on the deformation behavior depended on the crystallographic relationship between the grain boundary planes and the primary slip planes in the two component single crystals. When both of the primary slip planes in the component single crystals were parallel to the grain boundary, the difference of the stress-strain curves between the bicrystal and the component single crystal was not found. On the other hand, when the primary slip planes in the bicrystal were not parallel to the grain boundary, the grain boundary raised the flow stress of the bicrystal above that of the component single crystal. In case of the bicrystals in which the multiple slips take place in the component single crystals, no effect of the grain boundary on the deformation behavior of the bicrystal was observed.
  • 村上 澄男, 水野 衛
    1991 年 40 巻 449 号 p. 158-164
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Elaboration of the constitutive equations of creep and creep damage under irradiation for structural analyses in multiaxial states of stress is discussed. In order to formulate the continuous transition of swelling after the incubation period of neutron irradiation, the curvature parameter proposed by Bates et al. was introduced into the evolution equation of swelling. The constitutive equation of irradiation-enhanced creep, furthermore, was elaborated by taking account of the physical mechanisms of the flux-and fluence-dependence of dislocation behavior. As regards the transient creep, on the other hand, the creep law of McVetty type and Kachanov-Rabotnov creep-damage theory were modified to describe the irradiation-enhanced creep. The irradiation-induced creep was formulated by incorporating the SIPA (Stress-Induced Preferential Absorption) mechanism. Finally unirradiated creep, post-irradiation creep, and in-reactor creep of type 316 stainless steel at elevated temperatures were predicted by the elaborated constitutive equations. The validity of the equations was discussed by comparing the predictions with those of the corresponding experiments.
  • 松田 憲昭, 梅沢 貞夫, 児島 慶享
    1991 年 40 巻 449 号 p. 165-171
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper deals with the effects of two types of corrosion resistance coating, CoNiCrAlY and Al chemical vapour deposition (CVD) coating, on the fatigue-creep interaction life of a cast Ni base superalloy René80.
    Under a fatigue condition, CoNiCrAlY coating improved the resistance to surface crack initiation, while Al CVD coating reduced the number of cycles to surface crack initiation. However, the surface crack propagation rates of both the coated and non-coated specimens were about the same value. Under a fatigue-creep interaction condition, the number of cycles to surface crack initiation of the coated specimen increased in comparison with the non-coated specimen. The surface crack propagation rate of the coated specimen increased in comparison with the non-coated specimens.
    It was found that the fatigue life of the coated specimen was affected by the oxidation of the specimen surface and the properties of the coating meterial. The life under fatigue creep interaction was affected by the failure mechanism (intergranular cracking) of the base metal René80 rather than the oxidation and the properties of the coating material.
  • 森 誉延, 矢内 吉美, 福井 寛
    1991 年 40 巻 449 号 p. 172-177
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effect of nitrogen content on tensile properties of SUS304L with N content less than 0.21% and SUS316L less than 0.23% have been investigated at cryogenic temperatures and the following conclusions were obtained.
    (1) Complicated temperature dependence of 0.2% proof stress appeared in the range of lower N content in the temperature range from 220K to 77K. This phenomenon is probably caused by the stress induced ε matensitic transformation.
    (2) The increase of 0.2% proof stress with N content at 4K was larger than that with C content.
    (3) Work hardening was prominent in steels with lower N content and at lower temperatures. This is attributed to instability of austenite.
    (4) An elongation peak appeared slightly below the upper limit temperature of stress induced α' martensitic transformation.
  • 二川 正敏, 菊地 賢司, 武藤 康, 柴田 碧
    1991 年 40 巻 449 号 p. 178-184
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The graphite components in HTR (High Temperature gas-cooled Reactor) are subjected to impact force when an earthquake occurs. It is important from a viewpoint of seismic safety design to investigate the difference between impact and nonimpact strengths.
    Both bending strength and bending fatigue strength tests, therefore, were carried out under impact and nonimpact loads on two kinds of graphite materials, that is, isotropic and near-isotropic ones. The impact response analyses, in which a beam model was used by taking account of the contact behavior between the specimen and a tap, were performed to evaluate the relationships among impact energy, impact force and impact stress.
    The main conclusions obtained are summarized as follows;
    (1) A beam model taking account of the contact behavior through the Hertzian theory is applicable to describe the impact behavior.
    (2) The bending strength of graphite is independent of strain rate in the range 10-6 to 5l/s.
    (3) The strength of graphite is lower in impact fatigue than in nonimpact fatigue, irrespective of kind of graphite and specimen volume.
  • 高橋 清, 荻原 俊秀
    1991 年 40 巻 449 号 p. 185-191
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Effect of hydrostatic pressure was studied on the fracture velocity and morphology of cracked PMMA tensile plate specimens (108mm×30mm×5mm) of different molecular weights: Mv=2.3×106 and 2.0×105. Ultrasonic fractography was employed to precisely measure fracture velocity under a pressure of less than 150MPa; fracture instability occurred only under pressure of less than 10MPa. Fracture velocity, monitored in the middle part of a specimen, decreased with increasing pressure up to 50MPa, and above this remained almost constant. The way in which a specimen was chucked affected the velocity decrease. The molecular weight change had no discernible effect on fracture velocity under pressure. There was a morphological change in the fracture of specimens with the high and the low molecular weights loaded at pressures of over 100MPa and 50MPa, respectively; a cleavage type fracture tended to be replaced by a mixed cleavage-non cleavage type, particularly during the initial stage of fracture. The affected area featured many longitudinal fine streaks, each of which was composed of an array of small shear cusps.
  • 宮野 靖, 高村 幸夫, 鈴木 惠, 毛利 三知宏
    1991 年 40 巻 449 号 p. 192-198
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The flexural fracture behavior of unidirectional CFRP laminates (X) using pitch based carbon fibers XN40, which was recently developed as high grade fiber, was investigated by three point bending test over wide ranges of temperature and strain rate. At the same time, similar experiments were carried out for two types of CFRP, M and P, in which PAN based carbon fibers M40 and pitch based carbon fibers P55S are used, respectively. By comparing the results of three types of CFRP laminates, characteristics of CFRP(X) were clarified as mentioned below;
    (1) The flexural strength of CFRP(X) as well as the others remarkably changes with temperature and strain rate. The master curves of flexural strength can be constructed for those CFRPs by using the reciprocation law between time and temperature. The time-temperature shift factors of flexural strength in respective CFRP are in quantitatively good agreement with each other.
    (2) The region of reduced time is clearly divided into three parts by the mechanism of fracture for CFRP(X), that is, the micro-buckling of fibers as the initiation of fracture in the region of long reduced time, the compressive fracture of fibers in the region of medium reduced time and the tensile fracture of fibers in the region of short reduced time. In the region of long reduced time, the flexural strength of CFRP(X) is in good agreement with those of CFRP(M) and CFRP(P), which remarkably changes with reduced time. However, in the region of medium reduced time, the flexural strength of CFRP(X) shows characteristic behavior which is different from the others. The flexural strength of CFRP(X) remarkably changes with reduced time, although those of the others slightly change.
  • 中田 政之, 宮野 靖, 鈴木 惠, 服部 陽一
    1991 年 40 巻 449 号 p. 199-204
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    To investigate the time and temperature dependences of the fatigue behavior of carbon/aramid hybrid unidirectional FRP laminates (C/A hybrid FRP) in which CFRP layer was sandwiched between two AFRP layers, three point bending fatigue tests for CFRP, AFRP and C/A hybrid FRP were conducted at several levels of temperature and frequency. The flexural fatigue strengths of CFRP, AFRP and C/A hybrid FRP depended on temperature and frequency, and the reciprocation law between time and temperature held for these strengths. The flexural fatigue fracture of C/A hybrid FRP was classified into two modes by temperature, frequency and number of cycles to failure Nf. One is triggered by the tensile fracture of AFRP layer in the range of low temperature, high frequency and low Nf where the fatigue strength changes scarcely with temperature, frequency and Nf. The other is triggered by the compressive fracture of CFRP layer in the range of high temperature, low frequency and high Nf where the fatigue strength decreases remarkably with temperature, frequency and Nf.
  • 宮崎 則幸, 重國 智文, 宗像 健, 武田 展雄
    1991 年 40 巻 449 号 p. 205-210
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Tests were carried out to study the effects of matrix materials, reinforcement fibers, interface strength between matrix and fibers, impact angle, and particle velocity on the solid particle erosion behaviour of FRPs. Two types of FRPs were utilized for the erosion tests. One was the thermoplastic resin reinforced by short glass or carbon fibers. The other was the thermosetting resin reinforced by 8-shaft satin-woven glass cloths. The erodent particles used for the tests were SiC abrasives with the diameters of 100μm to 150μm. The FRPs with treated or untreated fiber surface were utilized as test materials to study the effect of interface strength between matrix and fibers.
    The following conclusions were obtained from the erosion tests.
    (1) Erosion rate is greater in FRPs than in neat resins.
    (2) The erosion rate of FRPs decreases with the decrease of fiber content.
    (3) The erosion rate of FRPs decreases with the increase of the interface strength between matrix and fibers.
    (4) The peak of the erosion rate of FRPs shifts to large impact angle owing to the inclusion of brittle fibers.
    (5) In FRPs, erosion rate R is related with particle velocity Vp as RVpn. The values of exponent n of FRPs are almost the same as those of neat resins.
  • 田中 利光, 山口 宗明, 堀 昭二, 田中 勝敏, 渡辺 信淳
    1991 年 40 巻 449 号 p. 211-216
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    The influences of glass transition temperature (Tg) of epoxy resins filled with graphite fluoride (C2F)n powders (C2F) in the range 0-30wt%, on friction and wear properties were investigated. The epoxy resins used for matrices were Tetrad® D and X (ER-D and X) cured with HHPA, the Tg of which measured by Rheovibron at 110Hz were 246°C and 236°C, respectively. It was observed by SEM photographs that the C2F particles were dispersed randomly in the composites.
    The limiting pV values of ER-D and X filled with 30wt% of C2F powders were higher than that of Epikote® 828 (ER-E) filled with 30wt% of C2F by 8.2 times. The friction coefficients (μ) of the composites were in the range of 0.1-0.2. The specific wear rates (W) of the composites were in the order of 10-5mm3/kg·mm and were lower than that of ER-E filled with C2F by 1/10 times. The limiting pV values of the composites which were filled with 30wt% of C2F treated with coupling agents were larger than those of the composites filled with untreated C2F by 1.4 times.
  • 星出 敏彦, 奥村 和雅, 井上 達雄
    1991 年 40 巻 449 号 p. 217-223
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Three-point bending tests were conducted using specimens of sintered silicon nitride ground in six types of condition, which were prescribed by the combination of the mesh-size of grinding wheel and the cutting depth. It was revealed by the Weibull statistical analysis that the stength was higher and its scatter was less in specimens ground by using a grinding wheel with larger abrasive grains. The relative estimation of residual stress induced by grinding was tried by using the indentation-flaw method to evaluate the fracture toughness simply. In this case, the crack formation resistance ratio, which was defined as the apparent fracture toughness measured on the ground surface divided by that on the surface without residual stress, was proposed to correlate the stength depending on the grinding condition. The crack formation resistance ratio became larger with an increase of strength. The tendency was ascribed to the variation of the intensity of compressive residual stress depending on the grinding condition. A simulation was carried out to discuss the dominant factor to affect the relation between the strength distribution and the grinding condition. In the analysis, the fracture mechanics model for cracks located in the region subjected to tensile stress was combined with the Monte Carlo simulation. The simulated result presented similar characteristics of the strength distribution as observed experimentally. The characteristics of the strength distribution was successfully explained by introducing the concept of superposing distinct strength distribution depending on the crack geometry.
  • 市川 昌弘
    1991 年 40 巻 449 号 p. 224-227
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Use of some mixed mode fracture criterion becomes necessary when reliability evaluation of ceramic components is made based on flaw distributions, since most components are subjected to multi-axial stresses in service conditions. The maximum energy release rate criterion is one of the wellknown criteria for mixed mode fracture. In the case of a mixed mode crack, the energy release rate, G, takes a maximum value, Gmax, when the crack extends in a certain direction. The maximum energy release rate criterion (Gmax criterion) assumes that unstable crack extension occurs when Gmax reaches a certain critical value. Unfortunately, a reliable analytical expression of Gmax in terms of the stress intensity factors has not yet been obtained. This is an obstacle to analytical treatments based on Gmax criterion. Thus, it was attempted in this paper to derive an analytical expression of Gmax for a two-dimensional crack. The approximate analytical expression Gmax=(KI2+3KII2+KIKI2+6KII2)/2E' was obtained, where KI(>0) and KII are the mode I and mode II stress intensity factors, and E'=E for plane stress and E'=E/(1-ν2) for plane strain with E and ν being usual elastic constants. From comparison of this expression with the exact value of Gmax evaluated numerically, it was shown that the proposed expression is quite accurate. It was also shown that the expression of Gmax given by Hellen and used by Lamon for reliability evaluation of ceramic components is not adequate.
  • 佐野 修, 民部 雅史, 平野 享, 工藤 洋三, 水田 義明
    1991 年 40 巻 449 号 p. 228-234
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    Oriented cracks and/or oriented joints in rocks produce anisotropic elasticity. When the rock has anisotropic elasticity, one must know more than two elastic constants to describe fully the elastic behavior of rocks under stress. In an anisotropic body, there are twenty-one elastic constants with respect to an arbitrary coordinate system. When a material has some sort of symmetry, a number of non-zero elements, with respect to the symmetry axes, can be reduced. In general, the full information of elastic symmetry has to be known, because the elastic constants of rock-forming minerals and rocks are determined by measuring elastic properties with respect to the elastic symmetry. In this study, it was tried to determine twenty-one elastic constants of anisotropic rocks, and to find symmetry axes of the rock, by using elastic wave velocities propagating in various directions. The calculated elastic constants and the axes of symmetry of Oshima granite agreed well with the published results which were determined in the assumption of orthorhombic elasticity with respect to the planes of oriented cracks.
  • 西川 出, 森川 自, 藤原 弘次, 三好 良夫, 小倉 敬二
    1991 年 40 巻 449 号 p. 235-241
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
    A new automated crack growth test system with the aid of an image processing technique was developed. This system consists of a mechanical stage with a CCD camera, an image processing unit and a personal computer. A CCD camera with an image guide scope was used to monitor the microscopic image of a crack tip. This image around the crack tip was processed and analyzed by using a template-scanning technique to make a real-time recognition of the crack tip. The crack length was determined from the detected crack tip location. The crack growth rate and stress intensity factor were also calculated and recorded on a magnetic medium. This system was widely applicable to various fracture mechanics tests with no limitations in sample shape, environment and so on. Several K-controlled fatigue crack growth tests both at room and elevated temperatures were conducted to demonstrate the reliability, performance and precision of this system.
  • 香川 満
    1991 年 40 巻 449 号 p. 242-248
    発行日: 1991/02/15
    公開日: 2009/06/03
    ジャーナル フリー
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