材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
49 巻 , 8 号
選択された号の論文の21件中1~21を表示しています
  • 佐藤 清, 山本 尚登, 山之内 猛
    2000 年 49 巻 8 号 p. 836-838
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    In this study, new methodology is proposed for the study on the fracture under Mode I impact load. Using this method, Mode I impact fracture experiment was carried out at room temperature to study the effect of impact velocity on the Mode I fracture strain of wood by using CT specimen. Impact velocity was about 8-18m/s. The materials used for the experiment were western hemlock, Japanese cypress, Alaska cedar, agathis and tamo lumbers.
    Mode I impact fracture strain is about half of Mode I static fracture strain.
  • 飯井 俊行, 服部 修次, 渡邊 勝彦
    2000 年 49 巻 8 号 p. 839-844
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper presents a practical equation to calculate the mode I stress intensity factor for an inner surface circumferential crack in a finite length cylinder subjected to axisymmetric and quartic distributed stress on the crack surface. The equation was derived by applying the authors' weight function for the crack. The equation is valid for wide ranges of mean radius to wall thickness ratio, Rm/W≥1, and of relative crack depth, a/W≤0.5. The equation can evaluate the effect cylinder length gives on the stress intensity factor and this effect should be properly considered for cylinders shorter than non-dimensional cylinder length βH≤5.
  • 三浦 直樹, 島川 貴司, 中山 康成, 高橋 由紀夫
    2000 年 49 巻 8 号 p. 845-850
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    J-integral is an effective inelastic fracture parameter for the flaw evaluation of cracked components at high temperature. The evaluation of J-integral for an arbitrary crack configuration and an arbitrary loading condition can be generally accomplished by detailed numerical analysis such as finite element analysis, however, it is time-consuming and requires a high degree of expertise for its implementation. Therefore, it is important to develop simplified J-integral estimation techniques from the viewpoint of industrial requirements. In this study, a simplified J-integral evaluation method is proposed to estimate two types of J-integral parameters. One is the fatigue J-integral range to describe fatigue crack propagation behavior, and the other is the creep J-integral to describe creep crack propagation behavior. This paper presents the systematization of the simplified J-integral evaluation method incorporated with the reference stress method and the concept of elastic follow-up, and proposes a comprehensive evaluation procedure. The verification of the proposed method is presented in Part II of this paper.
  • 島川 貴司, 三浦 直樹, 中山 康成, 高橋 由紀夫
    2000 年 49 巻 8 号 p. 851-856
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    J-integral is the feasible parameter to represent fracture behavior in non-linear regime. However there are many difficulties to calculate accurate J-integral in actual components. CRIEPI has been developing a simplified J-evaluation method based on the reference stress approach. This paper presents verifications of the proposed method through three representative problems. The first subject is the creep-fatigue crack propagation problem of test specimens such as CT and CCP. Calculated results are compared with those measured in experiments. Applicability to creep-fatigue problem is verified through this comparison. The second subject is the creep-fatigue crack growth problem of a plate with semi-elliptical surface crack. Estimated fatigue J-integral and creep J-integral are compared with finite element analysis results. Applicability to the surface crack problem is confirmed. The third subject is the creepfatigue crack growth problem of a cylinder under thermal stress. Applicability to thermal stress is also verified. These results show that J-integral values calculated by the proposed method coincides with experimental and finite element analysis results. It is confirmed that the proposed method is applicable for the flaw evaluation of cracked components at high temperature.
  • 許 金泉, 付 列東, 武藤 睦治
    2000 年 49 巻 8 号 p. 857-861
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Elastoplastic boundary element analysis is carried out to investigate the effect of linear hardening coefficient on the stress singularity and stress field near an interface edge in bonded dissimilar materials. The results show that the elastoplastic stress distribution near an interface edge can be divided into 3 regions, i.e., elastoplastic singular stress dominated zone, transition zone and elastic zone, sizes and properties of which depend on the size of yielding zone and the hardening coefficient. If the linear hardening coefficient is relatively large, the elastoplastic stress distribution agrees with the quasi-elastic theoretical result. It is also found that the transition zone increases and the elastoplastic singular stress dominated zone decreases with decreasing the hardening coefficient. If the linear hardening coefficient is small enough, the transition zone may become the main part of the yield zone, and the theoretical results may be correct only in a very small region near the edge, hence it would lose physical meanings for the evaluation of elastoplastic fracture. On the other hand, for small scale yield problems, the numerical results show that the behavior of stress distribution in the elastic zone is almost similar to the elastic theoretical results (i.e. the stress singularity order is almost the same), but the stress intensity coefficient becomes somewhat larger.
  • 許 金泉, 武藤 睦治, 劉 一華
    2000 年 49 巻 8 号 p. 862-866
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    An axisymmetric interface crack with frictional contact is theoretically analyzed. The eigen-equation determining the stress singular order, and the stress and displacement fields near the crack tip are deduced in details. Based on the results obtained by theoretical analysis, the condition under which the contact will occur is discussed. If the condition is not satisfied, the crack can be dealt as a crack with free surface. The results show that the stress singularity order is dependent on the material combination, the frictional coefficient, and also the direction of the relative displacement of the crack-face. When the crack has a contact region, the oscillatory singularity disappears, and the stress field near the crack tip is similar to that of a pure mode II crack, as it does in plane problems. However, to express the effect of material combinations on stress or displacement fields, three composite parameters are needed, while only two is needed in the plane problems.
  • 宮本 昭彦, 村上 敬宜
    2000 年 49 巻 8 号 p. 867-872
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Plate glasses of windows and doors of buildings are often destroyed by the bullets in the criminal cases using firearms. When a plate glass is impacted by a projectile, the Hertzian cone is produced behind the impact point of this glass. It is known that the apex angle of the Hertzian cone crack in Pyrex glass caused by small steel ball impact varies in a systematic manner with the impact velocity. However, there are few reports especially on the results caused by the lead bullet impact. In order to obtain the basic data to estimate the impact velocities and the incident angles of the projectiles, an experiment about the morphology of the Hertzian cone was carried out.
    In the experiment, projectiles (11mm dia. steel balls and 0.38 inch (9mm) dia. lead bullets) were shot onto the float plate glasses (soda-lime glasses). A strong correlation was found between the ratio of the Hertzian cone diameter to the plate glass thickness and the impact velocity. It was also found that the Hertzian cone caused by inclined impact became the size equivalent to the velocity component which is normal to the glass surface. Thus, the morphology of the Hertzian cone can be one of the indexes for estimating the impact velocities and the incident angles of the projectiles.
  • 西谷 弘信, 竹野 哲也, 福山 慶介, 立花 直樹, 才本 明秀
    2000 年 49 巻 8 号 p. 873-878
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fatigue crack propagation tests were carried out on the two types of plate specimens which were a strip with two edge cracks and a strip with an edge crack and a central circular hole. The experimental results were compared with the simulation analysis of crack propagation path based on the body force method. The main results were summarized as follows: (1) The crack propagation path is controlled by the Δσθmax criterion. (2) The crack propagation path in the fatigue tests is very close to that obtained by the simulation analysis. This means that the body force method is very effective in the simulation analysis of all propagation path.
  • 大路 清嗣, 辻上 哲也, 平岡 賢治
    2000 年 49 巻 8 号 p. 879-884
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    A method of simulating the behavior of fatigue cracks propagating in bonded dissimilar materials by using equivalent specimens made of single constituent material was proposed. The equivalent specimens reproduced the same elastic characteristics with those of the bonded dissimilar materials by replacing the effect of elastic constant by that of the specimen thickness, and removed the effect of weakened strength of the bonded interface. Using the proposed equivalent specimens, experiments were conducted simulating fatigue crack paths propagating near or across the slant (15° and 45°) interface of bonded steel-copper specimens. When the cracks propagated from the thick (equivalent to steel) side to the thin (copper) side, they grew almost straight across the interface, while the initial cracks were in the thin (copper) side, they propagated along the interface without penetrating into the thick (steel) side. These behaviors were quite similar to the actual ones directly observed with the real bonded steel-copper specimens. The proposed concept of the equivalent specimen was confirmed to be useful in simulating the behavior of fatigue cracks in bonded dissimilar materials.
  • 山中 光一, 槙山 和延
    2000 年 49 巻 8 号 p. 885-886
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    The cavitation erosion is generally known as one of damages due to a liquid. It has two occurrence processes which are flowing cavitation and vibrational cavitation. In this report, we introduce about results of observation of damaged surfaces that formed due to them.
  • 中平 敦, 西村 修一, 上田 智
    2000 年 49 巻 8 号 p. 887-891
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fe-substituted mordenite, Al-mordenite (Al end-member) and Fe-mordenite (Fe end-member) were synthesized in the Na2O-Al2O3-Fe2O3-SiO2-H2O system under TEA (tetraethylammonium) as a template by hydrothermal method. The hydrothermal process was performed in a stainless Morey bomb at 150°C. The continuous solid solution of Fe into Al-site in mordenite was obtained for mordenites with Al-Fe molar ratio (75/25, 50/50, 25/75). The mordenite crystal with Al-end member showed a tablet-like structure with 10μm diameter and 5μm thickness. The morphology of Fe-substituted mordenite was platelet shaped with 10μm in size. Fiber-like Fe-mordenite grew up to 30μm in length and 5μm in diameter. TEA was decomposed in air atmosphere at 440-450°C for Al-mordenite, Fe-mordenite, and Fe-substituted mordenites.
  • 望月 千尋, 木村 雄二
    2000 年 49 巻 8 号 p. 892-898
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Carbon fiber reinforced carbon (C/C) composites have light weight, high strength, high elastic modulus and high temperature strength in an inert atmosphere. However, carbon materials can actively react with oxygen in oxidation environment at above 500°C. Therefore, it is necessary to investigate about the oxidation mechanism of C/C composites on basis of grahitized microstructure. And also, oxidation behaviors of C/C composite made by different types of carbon fiber have not been made clear. In this study, oxidation behavior of C/C composites with different two types reinforcing fiber were investigated at high temperature in air by measuring weight loss with oxidation time and by examining it's graphitization and microstructure. Then, mechanical properties of oxidized C/C composites were investigated by 3-point bending test under span ratio of 4. As a result, the oxidation rate of C/C composites with Carbon Fiber heat-treated at higher temperature shows smaller value than that of Carbon Fiber heat-treated at the lower temperature. Furthermore, the difference in the oxidized morphologies is recognized dependending upon the oxidation temperature and the type of Carbon Fiber. And, in mechanical properties, the reduction of shear strength was preferentially recognized in case of the specimen oxidized at 600°C comparing to that oxidized 1000°C, even when the total weight loss is almost the same.
  • 小倉 敬二, 西川 出, 本橋 裕之, 岡野 公泰
    2000 年 49 巻 8 号 p. 899-904
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    High temperature flexural fatigue behavior was investigated on Si3N4 ceramics at 1173K and 1273K. The present study was focused on examining a beneficial effect of compressive loading on fatigue resistance. Fatigue resistance of smoothed samples was found to increase under fully reversed loading beyond those under pulsating loading and sustained loading. Crack growth tests were made to understand this behavior. Enhanced resistance under reversed loading was observed among sustained, pulsating and reversed loading. Compressive loading caused a recovering effect for the damage at crack tips, resulting in the beneficial effect on the high temperature fatigue resistance of smoothed samples under fully reversed loading.
  • 高橋 学, 岡部 永年, 朱 霞, 賀川 賢一郎, 小林 英男
    2000 年 49 巻 8 号 p. 905-911
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    A major problem in ceramic/metal joint is thermal expansion coefficient mismatch between ceramics and metal. This thermal expansion coefficient mismatch causes serious residual stresses at the interface of the ceramic/metal joint, which generated during joint-cooling process. Then, an interlayer, which is ductile metal such as copper, nickel and so on, is inserted between ceramics and metal because of relaxing the residual stress. It should be considered that thickness of interlayer have significant influence on the joint strength with considering the residual stress.
    In this study, it paid attention to the thickness of interlayer, and the optimum thickness of Interlayer was discussed from a viewpoint of the stresses based on simulation model analysis as well as 4 point bending tests, considering the residual stresses, which were analyzed using three-dimensional plasto-elastic finite element method. As a result of the analysis, residual stress increased with decreasing of the interlayer thickness. The superposing stress of the applied bending stress and the residual stress showed minimum value in the case of the interlayer thickness of 0.2mm. On the other hand, paying notice to the result of the bending test as well as the analysis, the joint specimen showed the highest bending strength in the case of the interlayer thickness of 0.2mm. Furthermore, the scatter of joint strength is apparently small in this thickness compared with in the other thickness.
  • 荒井 正行, 岩田 宇一, 佐久間 俊雄, 斎藤 正弘
    2000 年 49 巻 8 号 p. 912-918
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    In this study, a delamination initiation strength evaluation method of thermal barrier coating (TBC) using in a high-temperature component in a land based gas turbine was proposed, and the effect of the thermal aging on the TBC delamination initiation strength was investigated. As obtained results, (1) the delamination tests based on a four point bending were carried out by using a small specimen with a notch in TBC layer. It was found that the delamination occured at a top coating layer beside the interface between the top coating and the bond coating layer. (2) the delamination initiation strength (decohesion), which was obtained from an average of a stress concentration along the interface around the notch root, was about 120MPa. By subjecting the specimen to the thermal aging for more than about 1000 hour, the delamination strength was reduced by about 20MPa. (3) In a cross section of a long term thermal-aged specimen, the thermally growth oxide (TGO) pahse, α-Al2O3, was observed at the interface between the top coating and the bond coating by EDX analysis. It was found that the delamination initiation strength was inversely proportional to the TGO layer thickness.
  • 駒崎 慎一, 岸 繁男, 庄子 哲雄, 千葉 秀樹, 鈴木 康吏
    2000 年 49 巻 8 号 p. 919-926
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Thermal aging embrittlement of newly developed W alloyed 9%Cr ferritic steel KA-STBA29/KA-STPA29 (ASME T92/P92) has been investigated. In order to clarify the controlling factor of the embrittlement, Charpy impact tests and determination of precipitates have been carried out using materials aged under various conditions. The decrease in the upper and lower shelf energies and the increase in the fracture appearance transition temperature (FATT) due to thermal aging were caused by the precipitation and coarsening of Laves phase. The decrease in the impact toughness was found to be uniquely correlated with the increase in the area fraction of Laves phase. In order to develop a non-destructive technique for detection of the thermal aging embrittlement, changes in electrochemical properties of KA-STBA29/KA STPA29 due to thermal aging have been investigated. The electrochemical polarization technique has been applied to thermally aged materials. Experimental results on electrochemical polarization measurements revealed that the peak current density “Ip” which appeared at a specific potential during potentiodynamic polarization measurements in 1N KOH solution linearly increased with the degree of embrittlement evaluated by the impact energy at 0°C. The increase in Ip corresponded to the increase in selective dissolution of Laves phase. As a consequence, the degree of thermal aging embrittlement can be estimated by the electrochemical technique.
  • 佐野 清史, 松本 典人, 末岡 英二, 前田 敏, 中村 勇, 宮川 豊章
    2000 年 49 巻 8 号 p. 927-934
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Instead of bentonite mortar used a lot of filling materials, the authors considered the use of anti-washout underwater concrete satisfying the quality requirements for filling 50-cm thick confined spaces in water between crushed stone foundations and the bottoms of immersed tunnel elements. The concrete is required to have high fluidity to permit filling of thin and extensive spaces, adequate segregation resistance and excellent pumpability over a long distance. The authors investigated the performance of anti-washout underwater concretes by adjusting the mixture proportions with the aim of reducing the dosage of viscosity agent. The placeability and filling capability of the selected concrete was then confirmed by pumping tests and mock-up tests. The concrete was proven to have stable properties by the quality tests in actual production, retaining its placeability throughout the transportation and placing processes.
  • 山本 俊浩, 百武 秀
    2000 年 49 巻 8 号 p. 935-940
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Failure of notched FRP plates under static or fatigue loading is governed predominantly by the severity near the notch root. The severity is determined by both stress concentration and similarity of stress distribution near the notch root. In the present paper, a fatigue failure criterion based on the concept of severity near the notch root mentioned above is subjected to further experimental scrutiny. The investigation is accomplished by obtaining experimental data on intermediate notch-root radii specimens of a glass fiber-reinforced polycarbonate in pulsating tension. The process of initiation and growth of fatigue damage near the notch root was measured by means of the luminancemeasuring technique using a CCD camera. Closer observation of the microfracture in the fatigue-damage zone revealed the process of the luminance decline along with the increase of loading cycles. The experimental result shows that the number of cycles at the fatigue damage initiation, Nd was governed predominantly by both notch-root radius ρ and the maximum elastic stress σmax at the notch root, while it was independent of notch depth. Furthermore, the σmax has a one-to-one correspondence with the Nd when the size of fatigue-damage zone reached the half value of the notch-root radius ρ. On the basis of the concept of severity near the notch root mentioned above, the experimental results can be explained.
  • 上野谷 敏之, 藤井 透
    2000 年 49 巻 8 号 p. 941-947
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    The development and validation of thermoelastic damage analysis (TDA) is described to characterize damage in carbon fiber (CF) fabric composites. CF composites are suddenly ruptured without appearing obvious decrease in modulus with load increase, whereas often used as structural materials. We need to detect and estimate early damage, to monitor the damage progress, and to predict residual life of the materials. The TDA can greatly enhance conventional thermoelastic stress analysis (TSA) image of composites including early damage, which illustrates stress image having stress changes due to damage initiation/progression and also is very noisy due to the microscopic heterogeneity and weave construction of composite materials. The advantage of the TDA is demonstrated with evaluation of the damage in the plain-weave CF/plain epoxy composites and the toughened one with rubber-modified epoxy under fatigue loading as well as cyclic stepwise loading. The TDA images from the composites remarkably depended on the matrices in the composites. The TDA results compared well with those obtained using different NDT-techniques: scanning acoustic microscopy, acoustic emission technique, and edge replica technique. The TDA offered valid damage information in features and amount of stress release and ability to determine quantitative estimation of fatigue damage was also discussed.
  • 1. 地盤改良と環境問題総論
    嘉門 雅史
    2000 年 49 巻 8 号 p. 948-954
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 大門 静史郎
    2000 年 49 巻 8 号 p. 961-962
    発行日: 2000/08/15
    公開日: 2009/06/03
    ジャーナル フリー
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