# Fileset [fgm-2000-405-804.xlsx](https://mdr.nims.go.jp/filesets/fcf708f5-3d67-407b-9a47-537d5dfe5887/download) ## Creator National Institute for Materials Science ## Rights ## Other metadata [Functionally Graded Materials (FGM2000) (pp.405-804)](https://mdr.nims.go.jp/datasets/bbe3f75d-9684-491c-932e-ecee7c770bbd) ## Fulltext Sheet1 BookTitle_j BookTitle_e Volume/Issue Issueddate Page Title_j Title_e AuthorList_j AuthorList_e Abstract Language Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 405-413 2相TiC+TiB2傾斜セラミックプレフォーム TWO-PHASE TiC+TiB2 GRADED CERAMIC PREFORMS Yehuda Seidman, Natalie Frumin, Naum Frage, Moshe P. Dariel Yehuda Seidman, Natalie Frumin, Naum Frage, Moshe P. Dariel A varying rate of sintering within a green compact can be taken advantage of in order to generate a graded porosity in ceramic preforms. The rate of sintering in ceramic mixtures often depends on the relative ratio of the components. TiC and TiB2 do not interact up to 2500 deg.C and are well wetted by liquid Al. Oxygen-free TiC may be fully densified at 1600 deg.C, whereas TiB2 undergoes sintering only at T>1800 deg.C. The sintering behavior of TiC+TiB2 mixtures was established and a synergistic densification effect observed. Graded preforms were built by stacking layers that had a different ratio of the two components. The sintering rate of each layer was a function of the relative content of its components. The sintered preforms were infiltrated with molten Al and hardness profiles were determined in the resulting graded ceramic-metal composites. English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 415-422 炭化ホウ素-アルミナサーメット傾斜材料 GRADED BORON CARBIDE-ALUMINUM CERMETS N. Frage, L. Levin, M. P. Dariel N. Frage, L. Levin, M. P. Dariel "One possible approach for the fabrication of graded boron carbide-aluminum cermets is based on the infiltration of molten aluminum into a ceramic preform that displays graded porosity. Unidirectional graded porosity of the ceramic preform was achieved by sintering stacked layers of B4C+TiO2 powder mixtures. Reactive sintering takes place between the two components at a rate that strongly depends on the relative amount of TiO2. Upon infiltration of the porous preform with the molten metal, a graded ceramic-to-metal ratio, according to required specifications, allows generating desired property profiles and paves the way for a variety of specifications. Hardness profiles of the final composite that can be built depend on the nature of the ceramic preform, on the processing parameters and on the characteristics (thickness, number) of the initially stacked ceramic powder layers." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 423-430 炭化ホウ素-アルミナ多層傾斜複合材料 GRADED MULTILAYER BORON CARBIDE-ALUMINUM COMPOSITES F. Zhang, K. P. Trumble, K. J. Bowman F. Zhang, K. P. Trumble, K. J. Bowman "Fully dense boron carbide-aluminum composites with graded multilayers were prepared by liquid aluminum infiltration of boron carbide preforms produced by centrifugal casting. The amounts of secondary phases were effectively suppressed by repaid spontaneous infiltration. Young's modulus, microhardness, SEVNB fracture toughness and flexural strength were measured and correlated to microstructure and fractography. The results are compared with models for composite properties." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 431-438 ムライト/イットリア安定化正方晶ジ ルコニア多結晶体/アルミナ浸溶傾斜複合材料のトランスフォーメション安定性および機械的特性 TRANSFORMATION STABILITY AND MECHANICAL PROPERTIES OF INFILTRATED FUNCTIONALLY GRADED MULLITE/YTTRIA-STABILIZED TETRAGONAL ZIRCONIA POLYCRYSTAL/ALUMINA COMPOSITES Zhenbo Zhao, Cheng Liu, Derek O. Northwood Zhenbo Zhao, Cheng Liu, Derek O. Northwood "A novel infiltration method for processing mullite/yttria-stabilized tetragonal zirconia polycrystal/alumina (mullite/3Y-TZP/Al2O3) composite with graded transformation stability is described. This process involves infiltrating porous 3Y-TZP/Al2O3 composite preforms with a solution of ethyl silicate, followed by sintering at 1600 deg.C and 1700 deg.C for 2.5 hours. The resultant material has a homogeneous 3Y-TZP/Al2O3 core encased with a graded and heterogeneous layer of mullite/3Y-TZP/Al2O3. Analysis by X-ray diffraction and energy-dispersive spectrometry has revealed the existence of a concentration gradient of mullite, with the concentration decreasing with increasing depth into the sample. The graded composite displays a gradual change in thermal expansion values due to the presence of mullite. The partial loss of the Y-TZP/ Al2O3 composite's mechanical strength and fracture toughness due to the introduction of Al2O3, can be prevented." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 441-449 酸化ナノ層を持つ窒化ボロン微粒子のコンフォーマル・エンカプセレーション CONFORMAL ENCAPSULATION OF FINE BORON NITRIDE PARTICLES WITH OXIDE NANOLAYERS Jeffrey R. Wank , Alan W. Weimer, John D. Ferguson, Steven M. George Jeffrey R. Wank , Alan W. Weimer, John D. Ferguson, Steven M. George "Alumina (Al2O3) was deposited on boron nitride (BN) particles with atomic layer control using alternating exposures of Al(CH3)3 and H2O. The sequential surface chemistry was monitored in vacuum using transmission Fourier transform infrared (FTIR) spectroscopy studies on sub-micron sized BN particles. Transmission electron microscopy (TEM) studies revealed extremely uniform and conformal nanometer thick Al2O3 coatings on the BN particles. X-ray photoelectron spectroscopy (XPS) analysis was consistent with conformal Al2O3 coatings. These results illustrate the potential of sequential surface reactions to deposit ultra-thin Al2O3 coatings on BN particles.Process scale-up is currently being studied using a vibration-assisted, low pressure (<50 torr) fluidized bed apparatus. One consideration is the uniform coating of primary particles rather than aggregates. The fine individual BN particles form lightly bonded larger aggregates that remain in the bed during fluidization. A pulsed laser system has been used to investigate the mechanism of aggregate formation. Agglomerate size is dependent on vibrational force applied and superficial velocity, but not on pressure." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 451-458 電気泳動堆積法を用いた金属セラミック連続傾斜ジオメトリ化 CONTINUOUSLY GRADED METAL-CERAMIC GEOMETRIES USING ELECTROPHORETIC DEPOSITION (EPD) W. E. Windes, A. W. Erickson, Jeramy Zimmerman W. E. Windes, A. W. Erickson, Jeramy Zimmerman "A graded Ni-Al2O3 structure was deposited on a nickel substrate using Electrophoretic Deposition (EPD) methods. Simultaneous deposition of metallic and ceramic particles was achieved by adjusting the solid particle density, electrolytic bath, and electrical potential allowing similar electrophoretic behavior between metallic and ceramic powders in the slurry. Deposition parameters for alumina-nickel cermet compositions were determined allowing a certain degree of control over the layer geometry and compositional gradient. Layered and continuously graded FGM structures transitioning from pure nickel to pure alumina were fabricated. After deposition ""green"" deposits were dried, consolidated in a hot press at 1350 deg.C, and characterized for compositional consistency and morphology in the microstructure of the layers." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 459-466 機能傾斜超硬金属の電気泳動堆積法 ELECTROPHORETIC DEPOSITION OF FUNCTIONALLY GRADED HARDMETALS S. Put, J. Vleugels and O. Van der Biest S. Put, J. Vleugels and O. Van der Biest "The possibility to manufacture functionally graded hardmetals by electrophoretic deposition (EPD) is investigated. WC-Co graded materials with a gradient in cobalt content were processed by EPD, cold isostatic pressing and sintering. Most attention is focused on obtaining a fully dense material without losing the cobalt gradient during sintering. The resulting graded material showed a continuous variation in composition, microstructure and mechanical properties. The cobalt content increases from 6wt% on the hard side to 17wt% on the soft side. The Vickers hardness is found to increase continuously from 9 to 21 GPa." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 467-474 遠心鋳造法パラメータのAl-Si/SiCp FGMの構造および特性への影響 INFLUENCE OF CENTRIFUGAL CASTING PARAMETERS ON THE STRUCTURE AND PROPERTIES OF Al-Si/SiCp FGMs L. A. Rocha, A. E. Dias, D. Soares, C. M. Sa, A. C. Ferro L. A. Rocha, A. E. Dias, D. Soares, C. M. Sa, A. C. Ferro "Al-Si metal matrix composites selectively reinforced at the surface (SiC) may be considered as advanced materials, aimed to be used in the automotive industry in components requiring high wear resistance, high bulk toughness or even a thermal barrier at the surface.In this work centrifugal casting was used to produce Al-Si/SiCp FGMs. The main aim of the work was to study the influence of the centrifugal casting parameters on the structure and properties of the FGM. Centrifugal acceleration, pouring temperature and mold temperature were the studied variables. Both the individual contribution of each parameter, and of their combination on the evolution of the structure and hardness were investigated. Results suggests that for a given alloy/particle mixture, the characteristics of the material depends essentially on the pouring temperature and centrifugal acceleration. By the correct control of the above variables it is possible to produce FGMs with reproducible properties." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 475-482 反応鋳造法で製造されたNiAl/スチール結合の微細構造 MICROSTRUCTURE IN NiAl/STEEL JOINT PRODUCED BY REACTIVE CASTING METHOD 松浦清隆、工藤昌行、Hiroshi Kinoshita、Heishichoro Takahashi Kiyotaka Matusuura, Masayuki Kudoh, Hiroshi Kinoshita and Heishichoro Takahashi "A NiAl block has been produced by pouring aluminum and nickel liquids onto a steel block placed in the bottom of a crucible. Due to an exothermic reaction between the elemental liquids, the temperature of the liquid mixture rises very quickly and exceeds 2800K, which is extremely high compared to the pouring temperatures of 1023K for aluminum and 1773K for nickel. The liquid mixture melts the surface of the steel block and soon solidification of NiAl containing small amount of iron starts at the steel surface, and finally the NiAl and steel are strongly joined after solidification. The microstructure at the joint interface has a very fine dual-phase structure of rod-like beta-NiAl and gamma-ferrite. The morphology of the beta-NiAl gradually changes from rod to round grain, as the distance from the interface increases. This gradual change in microstructure brings about a high joint strength exceeding 220MPa." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 483-489 ディップコーティングによるジルコニア-ニッケル機能傾斜材料の作製 FABRICATION OF ZIRCONIA-NICKEL FUNCTIONALLY GRADED MATERIAL BY DIP-COATING Jingchuan Zhu, Mingwei Li and Zhongda Yin, Jae-Ho Jeon Jingchuan Zhu, Mingwei Li and Zhongda Yin, Jae-Ho Jeon "A slurry dip-coating technique was developed for fabrication of zirconia-nickel functionally graded material (FGM). The rheological behavior of ZrO2-Ni-ethanol slurry was characterized by viscosity test. The amount of polyvinyl butyral (PVB) additives, which served as the dispersant and binder in ZrO2-Ni ethanol slurry, was optimized. The stainless steel substrate was coated several times by dipping in the slurries, and followed by drying in air every dipping. After debinding in Ar, the coated FGM plate was finally hot pressed at 1300deg.C for 1 hour under 5MPa. Microstructural observations of the sintered FGM specimens reveal that the graded layers were formed on the substrate, in which no defects such as small cracks and residual pores were observed." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 491-498 遠心in-situ法で作製されたin-situ Al-Al3Ni FGMにおける粒径分布 PARTICLE SIZE DISTRIBUTIONS IN in-situ Al-Al3Ni FGMs FABRICATED BY CENTRIFUGAL in-situ METHOD 松田公一、渡辺義見、福井泰好 Koichi MATSUDA , Yoshimi WATANABE, Yasuyoshi FUKUI "In-situ Al-Al3Ni FGMs were fabricated by the centrifugal in-situ method. The microstructures were observed and the composition gradients were studied. A detailed evaluation of particle size distributions within FGMs was also conducted because the particle size distribution in composite materials plays an important role in controlling the mechanical properties. It is revealed that both volume fraction and particle size had graded distributions within the in-situ FGMs. Smaller particle size was obtained in case of the larger applied G number and the smaller initial Ni content in an Al-Ni master alloy. It is concluded that the particle size distribution within the FGMs arises from a difference in cooling rate." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 501-512 傾斜機能材料のための多重極積分分析 BOUNDARY INTEGRAL ANALYSIS FOR FUNCTIONALLY GRADED MATERIALS L. J. Gray, T. Kaplan, J. D. Richardson, Glaucio H. Paulino L. J. Gray, T. Kaplan, J. D. Richardson, Glaucio H. Paulino "Free space Green's functions are derived for functionally graded materials (FGMs) in which the thermal conductivity varies exponentially in one coordinate. Closed form expressions are obtained for the time independent (steady state) equation in three dimensions. The corresponding boundary integral equation formulation for this problem is derived and has been implemented numerically using a Galerkin approximation. The results of test calculations are in excellent agreement with exact solutions and finite element simulations." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 513-520 傾斜機能材料の計算マイクロメカニクス COMPUTATIONAL MICROMECHANICS OF FUNCTIONALLY GRADED MATERIALS Peng-Cheng Zhai, Qing-Jie Zhang, Run-Zhang Yuan, 森谷信一 Peng-Cheng Zhai, Qing-Jie Zhang, Run-Zhang Yuan, Shin-Ichi Moriya "In this paper, the computational micromechanical method, which is combined with the Digital Image Processing Technique, the Mesh Auto Generation Technique and the Finite Element Analysis Method, is developed for prediction of the effective properties of the interlayers of functionally graded materials and for the local response analysis of functionally graded materials under special loads. Emphasis is put on the local response analysis. As a numerical example, the microscopic responses of a ZrO2/Ni FGM coating under thermal shock load are analyzed by the computational micromechanical method." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 521-528 逆解析によるFGM特性の測定 DETERMINATION OF FGM PROPERTIES BY INVERSE ANALYSIS Toshio Nakamura, Sanjay Sampath Toshio Nakamura, Sanjay Sampath "As the use of FGMs increases, an effective method to characterize their properties must be sought. In general, when FGMs are manufactured, their composition profile and effective material properties need to be verified. However, due o spatial variation of their properties, it is often difficult to make direct measurements of parameters which define FGM properties. In order to alleviate the difficulties, a new procedure based on the inverse analysis, which solely relies on micro-indentation records, is introduced. Specifically, the Kalman filter technique is utilized to estimate the FGM composition profile through-thickness and the stress-strain transfer parameter that defines the effective mechanical properties of FGM. Our simulation study shows promising results when records from two differently sized indenters are employed." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 529-536 随伴方程式を用いた組成傾斜中間層の最適化 USING ADJOINT EQUATIONS TO OPTIMIZE COMPOSITIONALLY GRADED INTERLAYERS Dj. Boussaa, H.D. Bui Dj. Boussaa, H.D. Bui "We consider an assemblage consisting of 2 homogeneous parts made of dissimilar materials and a functionally graded interlayer inserted between the two parts for thermal stress relief. A method is proposed to find the interlayer composition profile that minimizes stresses in the assemblage when its temperature is varied from an initial, uniform temperature to another uniform temperature. The optimization problem is (1) set as an optimal control problem whose control is the volume fraction of one of the two materials, (2) discretized using the finite element method, and (3) solved using the adjoint equations. A numerical example is investigated for which it is found that the optimal composition has jumps at the interface between the interlayer and the homogeneous parts." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 537-544 変形加工中に起こるマクロ組成傾斜材料の挙動のFEMシミュレーション FEM SIMULATION OF THE BEHAVIOUR OF GRADED MATERIALS WITH MACROSCOPIC COMPOSITION GRADIENT DURING DEFORMATION PROCESSES Sven Rassbach, Wolfgang Lehnert Sven Rassbach, Wolfgang Lehnert "The development of the graded materials is motivated by the local adaptation of the material composition to the specific application. Many of the processes used for the manufacture of graded materials have procedure-specific limitations concerning component complexity or gradient design. Therefore, graded materials should further be processed by deformation behavior of graded materials were carried out. These investigations show promising results. It is expected that technological compressive deformation processes can be applied in order to produce components with a graded material composition." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 545-552 ガラス成形ダイおよびツールのための傾斜コーティングシステムの設計における有限要素解析 FINITE ELEMENT ANALYSIS IN DESIGN OF A GRADED COATING SYSTEM FOR GLASS FORMING DIES AND TOOLS D. Zhong, G. G. W. Mustoe, J. J. Moore, S. Thiel, J. Disam D. Zhong, G. G. W. Mustoe, J. J. Moore, S. Thiel, J. Disam "Finite element analysis (FEA) is being used as an integral part of an overall research program that is being conducted to develop a non-sticking, oxidation resistant, and wear resistant coating system for glass molding dies and forming tools. The FEA was performed with the general purpose FE code in the MARC K7.32 system. In this work, a non-linear thermomechanical FE model has been used to analyze the residual stress generated in the coating system during a simulated glass molding process, and to predict an optimal coating architecture with minimized residual stress and optimized stress distribution. The results suggested that the proposed graded coating architecture could benefit the performance of the coating system for glass forming dies and tools. The methodology described in this paper can be used o explore the effects of die geometry, die materials, coatings, and process parameters, etc. on die life." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 553-559 アルミナ/銅傾斜機能材料のモデリング MODELLING OF ALUMINA/COPPER FUNCTIONALLY GRADED MATERIALS M. Gasik, M. Friman, 神戸満 M. Gasik, M. Friman, M. Kambe "An alumina-copper functionally graded material (FGM) joint was examined to determine the optimum grading of composition. The aim was to find the best grading profile in regard to minimal residual thermal stress and maxmal thermal conductivity. The modeling of the Al2O3-Cu system was done at two application temperatures, 20deg.C and 700deg.C.Thermal stress is generated in the joint due to the different thermal expansion coefficients of Al2O3 and Cu. The linear plate model supplemented with a micromechanical model was used for thermoelastic behavior of the joint. The properties of the materials were evaluated with the micromechanical model for different grading functions in the FGM layer.A thin Al2O3-rich FGM layer is found to be better from the point of view of ""stress-electrical resistance-thermal conductivity"" combination. Increasing the amount of copper in the graded layer makes residual stress dominant though thermal conductivity increases." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 563-570 マイクロ波焼結を施した傾斜機能材料における残留応力状態の調査 INVESTIGATIONS OF THE RESIDUAL STRESS STATE IN MICROWAVE SINTERED FUNCTIONALLY GRADED MATERIALS D. Dantz, Ch. Genzel, W. Reimers, T. Buslaps D. Dantz, Ch. Genzel, W. Reimers, T. Buslaps The residual stress distribution in microwave sintered functionally graded materials (FGM) consisting of Ni and 8Y-ZrO2 was analyzed by non-destructive diffraction experiments. In order to evaluate the residual stress state in the near surface region as well as in the bulk of the material, complementary methods were applied. Using conventional X-ray sources the residual stress at the surface were investigated by the sin2 (psi) -method. For the interior of the material high energy synchrotron radiation was used allowing high spatial resolution. The residual stress state was found to be related to the compositional distribution of the present phases, their volume fraction and their coefficients of thermal expansion as well as to the additive ZrSiO4 in the ceramic rich region of the gradation. Additionally, the line broadening was analyzed by a single-line method with respect to plastic deformation of the metallic phase, in order to characterize the microstructure of the samples. English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 571-578 傾斜機能材料のための空間分解した温度伝導率測定 SPATIALLY RESOLVED THERMAL DIFFUSIVITY MEASUREMENTS FOR FUNCTIONALLY GRADED MATERIALS Hans Becker, Theo Tschudi, Achim Neubrand Hans Becker, Theo Tschudi, Achim Neubrand "Knowledge of the position dependent thermal diffusivity of FGMs is important in situations where these materials are exposed to thermal shock-however measurements with conventional techniques require uniform samples and have no spatial resolution. A laser-based photothermal beam-deflection scheme is presented that is capable of thermal diffusivity measurements with a spatial resolution down to 50 micrometer. For homogeneous materials, the thermal diffusivity values retained by this method agree very well with the well-established laser flash technique. The new method was used to determine local thermal diffusivity values on graded Al2O3/Al composites and a graded AlCu alloy with a high spatial resolution." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 589-586 Al-Si/SiCp複合材のトライボ特性：MMC's vs. FGM's TRIBOLOGICAL CHARACTERIZATION OF Al-Si/SiCp COMPOSITES: MMC's vs. FGM's J. R. Gomes, A.S. Miranda, D. Soares, A.E. Dias, L. A. Rocha, S. J. Crnkovic, R. F. Silva J. R. Gomes, A.S. Miranda, D. Soares, A.E. Dias, L. A. Rocha, S. J. Crnkovic, R. F. Silva "In this work, aluminum based materials were tested against gray cast iron in a pin-on-disk tribometer. Cast SiC particulate reinforced F3S-20S aluminum matrix composite as prepared by Duralcan, the same material after centrifugal casting to obtain functionally graded properties and the non reinforced Al-Si (Al12SiMg) alloy, were tested without lubrication, at room temperature, under a nominal load of 5N and constant sliding speed of 0.5ms**-1. Because of the poor mechanical response of non-reinforced Al-Si alloy, catastrophic wear is rapidly attained. For aluminum matrix composites, the wear resistance strongly increases due to the combined effect of reinforcing particles as load bearing elements and the formation of adherent tribolayers. FGM composites exhibited superior wear resistance when compared to homogeneous MMCs. It was also evidenced that the best tribological system tested corresponds to a FGM with ca.33% of SiC particles at the contact surface. The wear mechanisms were investigated using SEM/EDS and a comparative analysis is established between the functionally graded and non-graded materials." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 587-594 セラミック金属傾斜複合材の弾性特性の超音波特性 ULTRASONIC CHARACTERIZATION OF THE ELASTIC PROPERTIES OF CERAMIC-METAL GRADED COMPOSITES. R. Marks, E. Zaretsky, N. Frage, O. Tevet, Y. Greenberg, M. P. Dariel R. Marks, E. Zaretsky, N. Frage, O. Tevet, Y. Greenberg, M. P. Dariel "In graded ceramic-metal composites, the elastic properties vary in a pre-determined manner along certain directions. Gradients of elastic moduli can be established by generating spatial variations of the ceramic-to-metal ratio. The objective of the present study was to correlate composition and elastic moduli gradients in ceramic-metal composites, using sound velocity measurements.The elastic moduli of solids can be derived from the density and the values of the longitudinal and transverse ultrasonic wave velocity. A database of sound velocities and densities was established for homogeneous porous ceramics and cermets. Graded ceramic-to-metal composite were constructed by infiltrating with molten metal ceramic preforms that had a in-built graded porosity.Porosity gradients were generated in the single-phase, TiC, and in the two-phase, TiC-TiB2, systems. In the TiC-TiB2 system, the rate of sintering depends critically on the TiC/TiB2 ratio. In the TiC system, varying the ratio of fine to coarse-sized ceramic particles can change the rate of sintering. Stacked powder layers of different mixtures of the ceramic powders were sintered at 1550deg.C for one hour and subsequently infiltrated with molten Al.The sound wave velocity was measured parallel and perpendicular to the composition gradient. The sound velocity was measured in each layer perpendicular to the composition gradient. The results and the values obtained in homogeneous samples were used to derive calculated sound velocity values parallel to the composition gradient. These values were compared to the measured sound velocities parallel to the gradient. The agreement between the two sets of values was within 3%." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 595-602 位相シフトモアレ干渉法の応用 APPLICATIONS OF PHASE SHIFTED MOIRE INTERFEROMETRY Eric D. Steffler Eric D. Steffler "Full field, high resolution displacement measurements are essential to understand complex mechanical deformation and to validate numerical results. Moire interferometry is used to measure sub-micron displacements in regions of import such as near crack tip singularity fields, near interface deformation, shear-compression loaded fracture and mechanical response of graded materials. An overview of phase-shifted moire interferometry (PSMI) capabilities and limitations will be presented with specific examples of recent and ongoing projects." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 603-610 W-Cu FGMに置けるマクロおよびマイクロ応力の分散 DISTRIBUTION OF MACRO- AND MICRO-STRESSES IN W-Cu FGM Juergen Schreiber, Achim Neubrand, Thomas Wieder, Meinhard Stalder, Nail Shamsutdinov Juergen Schreiber, Achim Neubrand, Thomas Wieder, Meinhard Stalder, Nail Shamsutdinov "W-Cu FGM with different gradation profiles were fabricated by electrochemical gradation and infiltration. The composites produced by this method were free of porosity and had an interpenetrating network microstructure. Residual stresses along the gradient were analyzed by neutron diffraction. The observed micro-stresses are often higher and of opposite sign than expected from the thermal expansion mismatch. These results demonstrate that non-equilibrium effects such as inhomogeneous and fast cooling, plastic Cu deformation, and micro-cracks in the W matrix can have a large effect on micro- as well as macro-stresses. After annealing of the FGM the detected distribution of macro-stresses is in qualitative agreement with FEM calculations. A model is presented to explain the unexpected experimental behavior of stress and strain during thermo-mechanical load." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 611-618 温度センサーへの応用のための傾斜機能MoSi2-Al2O3管 FUNCTIONALLY GRADED MoSi2-Al2O3TUBES FOR TEMPERATURE SENSOR APPLICATIONS M. I. Peters, R. U. Vaidya, R. G. Castro, J. J. Petrovic, K. J. Hollis and D. E. Gallegos M. I. Peters, R. U. Vaidya, R. G. Castro, J. J. Petrovic, K. J. Hollis and D. E. Gallegos "MoSi2 and Al2O3 are thermodynamically stable elevated temperature materials whose thermal expansion coefficients match closely. Composites of these materials have potential for applications such as protective sheaths for high temperature sensors. MoSi2-Al2-O3 functionally graded tubes were fabricated using advanced plasma spray-forming techniques. Both continuously-graded and layered-graded tube microstructures were synthesized. The characteristics of the graded microstructures and the features of the graded mechanical properties of these tubes will be discussed." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 619-626 熱誘起応力を減らすための新しいセラミック金属システム結合法 A NOVEL METHOD OF JOINING CERAMIC-METAL SYSTEMS TO REDUCE THERMALLY INDUCED STRESSES K. Khene, C. S. Trueman, N. D. Tinsley, M.R. Lacey and J. Huddleston K. Khene, C. S. Trueman, N. D. Tinsley, M.R. Lacey and J. Huddleston "A novel method for ceramic-metal joining, applicable for a wide range of emerging Ceramic Matrix Composites (CMC) and cermets is described. It combines singularity removal from the free surface with the introduction of a functional gradient zone, achieved by preshaping the mating parts to obtain typically a regularly repeating interpenetration of the two surfaces. This shaping is performed by CNC electrical discharge machining the CMC (generally containing conductive dispersoid nitrides, carbides or borides), by the preshaped metal part. This paper presents Finite Element Analysis predictions for a range of interface geometries, along with experimental results, illustrating the merits of the process as demonstrated through mechanical testing of finished joints." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 627-634 多層法を用いた高熱伝導損失誘電体 HIGH THERMAL CONDUCTIVITY LOSSY DIELECTRICS USING A MULTI-LAYER APPROACH B. Mikijelj, J. O. Kiggans, T. N. Tiegs, P. A. Menchhofer, H. Wang, and H. T. Lin B. Mikijelj, J. O. Kiggans, T. N. Tiegs, P. A. MenchhoferH. Wang, and H. T. Lin "Lossy ceramics are used as load materials in devices that include both high power microwave sources and low power communication equipment. Desired properties of the materials are low porosity, high thermal conductivity, tailorable dielectric permittivity and loss, and good high temperature stability and mechanical properties. BeO-based composites have traditionally been used in these applications, but due to chronic beryllium disease health issues, the BeO materials are being replaced by AlN-based materials. The initial AlN substitutes did not have the desired thermal conductivities. By using a multi-layer approach, AlN-based composites having both high thermal conductivity and high dielectric loss have been produced." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 635-641 S-型B4C-SiC/C傾斜機能材料の設計および作製 DESIGN AND FABRICATION OF S-TYPE B4C-SiC/C FUNCTIONALLY GRADED MATERIALS Wei-ping Shen,Bo-zhong Wu,Jiang-tao Li,Chang-chun Ge B. Mikijelj, J. O. Kiggans, T. N. Tiegs, P. A. MenchhoferH. Wang,, H. T. Lin "Homogeneous specimens of (1-x)(80%B4C-20%SiC)-x C(x=0, 0.2, 0.4, 0.6, 0.8) (volume fraction (phi)c) and Functionally Graded Materials were hot-pressed respectively at 2000deg.C and 20MPa under Ar atmosphere. The density, water absorption, linear thermal expansion, elastic modulus and flexural strength of the ceramics and commercial graphite were tested. Cracks were observed in FGMs of 6 and 11 layers that are designed by linear function. The S-type function of compositional distribution as a design method resulted in a flexural strength of 216MPa and thermal shock resistance (delta)fc>500deg.C for the 11 layered (x=0.2~1) FGM of S-type." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 643-650 アルミナニッケルFGMプレートにおける熱衝撃試験 THERMAL SHOCK TEST ON ALUMINA/NICKEL FGM PLATE 淡路英夫、竹中宏光、阿部裕一、本多沢雄、西川直宏 Hideo Awaji, Hiromitsu Takenaka, Yuichi Abe, Sawao Honda and Tadahiro Nishikawa "This paper presented an analysis of temperature/ stress distribution in a stress-relief-type plate of functionally graded ceramic-metal-based materials and related results of thermal shock testing. The FGM disks with several gradual variations were fabricated using a powder stacking method and a pulse electric current sintering technique. Thermal shock tests on the FGM disks were performed as follows: The FGM circular disks were initially maintained at high temperature on the ceramic surface, and then cooled suddenly by cold water with constant velocity. The thermal shock resistance of the FGM was estimated using a critical temperature difference where cracks appeared on the ceramic surface. The results of the comparison of the analytical stresses and the critical temperature differences revealed that the stresses on the ceramic surface released significantly by the gradual variation of nickel across the thickness of the FGMs." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 651-658 モノリシック傾斜機能アルミナにおける衝撃損傷 IMPACT DAMAGE IN MONOLITHIC AND FUNCTIONALLY GRADED ALUMINA Premal Shah, Karl Jakus, John E. Ritter Premal Shah, Karl Jakus, John E. Ritter "Previous research has shown that Herzian cone cracking is suppressed in ceramic composites whose elastic modulus increases with depth below the surface. The objective of this research was to determine if these modulus-graded composites would also exhibit superior resistance to impact damage. Therefore, impact damage with spherical projectiles was studied in monolithic (plain) and modulus-graded alumina. The composite was fabricated by impregnating a dense, fine-grained alumina with an aluminosilicate glass having a lower elastic modulus than the alumina. This produced a modulus-graded alumina composite with decreasing glass content below the surface, thus causing the elastic modulus to monotonically increase with depth.Small spherical chrome steel and tungsten carbide projectiles were impacted on target specimens using a particle accelerator gas-gun. The tests entailed impacting the target with increasingly greater kinetic energy until ring cracks were observed by microscopic examination. These results were compared to Hertzian impact theory and previously published quasi-static Hertzian indentation data. It was found that the modulus gradation improved the impact damage resistance when the high elastic modulus tungsten carbide projectiles were used. No improvement was observed using the lower elastic modulus chrome steel projectiles. Monolithic alumina impacted with tungsten carbide projectiles followed the predictions of impact theory and agreed reasonably well with the previously published quasi-static data. However, modulus-graded alumina impacted with tungsten carbide projectiles and both monolithic an modulus-graded alumina impacted with steel projectiles did not follow either the theory or the previous data. It is believed that the low modulus steel deforms more upon impact than the alumina specimen, thus overshadowing the effects of the modulus gradient. On the other hand, the high modulus tungsten carbide does not deform appreciably during impact, allowing the modulus gradient to play a role in reducing the impact stresses and increasing the cracking threshold." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 659-666 傾斜機能材料における計算マイクロメカニクス、熱損傷モデル、衝撃応答の最近の発達 RECENT DEVELOPMENT IN THE COMPUTATIONAL MICROMECHANICS, THERMAL DAMAGE MODEL AND IMPACT RESPONSE OF FUNCTIONALLY GRADED MATERIALS Qing-Jie Zhang, Peng-Cheng Zhai, Li-Sheng Liu, Run-Zhang Yuan,森谷信一,　新野正之 Qing-Jie Zhang, Peng-Cheng Zhai, Li-Sheng Liu, Run-Zhang Yuan, Shin-Ichi Moriya and Masayuki Niino "The recent progress in the mechanics of functionally graded materials in the State Key Laboratory in cooperation with the Japanese National Aerospace Laboratory is reported. Emphasis is put on the computational micromechanics, thermal damage model and impact response. The computational micromechanics combines a construction technique for a two-dimensional random geometry composed of multiphases with a finite element method. The main feature of the micromechanics is its ability to exactly construct the real random and graded microstructure of FGMs and its ability to exactly determine the relationship between the microstructure and properties. The thermal damage model deals with the damage problem of FGM under cyclic thermal shock tests. A theoretical model is developed to examine an important thermal damage phenomenon: the coupling between the damage and heat conduction under cyclic thermal shock tests. The impact mechanics considers the dynamic response of a ceramic/metal FGM under high velocity impact. The propagation characteristics of impact waves across the interface between the ceramic and ceramic/metal interface are investigated. The effect of the composite properties and the ceramic thickness on the wave reflection across the interface is emphasized." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 667-673 層フライヤープレート材料による準等エントロピ圧縮波の生成 GENERATING QUASI-ISENTROPIC COMPRESSION WAVES VIA LAYERED FLIER-PLATE MATERIALS L. M. Zhang, C. B. Wang, Q. Shen, J.G. Li, J. S. Hua L. M. Zhang, C. B. Wang, Q. Shen, J.G. Li, J. S. Hua "Recent studies indicate that a kind of Layered Flier-Plate (LFP) materials can be used to generate quasi-isentropic compression waves in target materials as opposed to conventional shock loading. In this study several different plates were joined together to form such LFP materials with a parabolic distribution of density along the thickness direction. The impact experiments of the LFP materials on the targets were carried out on a light gas gun, and the histories of the free surface velocity of the targets were measured by VISAR. The results showed that wave profiles with a stepwise front were created, i.e. quasi-isentropic compression waves had been successfully generated via LFP materials." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 675-682 遠心法で作製されたAl-Al3Ti FGMの摩耗抵抗の異方性 ANISOTROPY OF WEAR RESISTANCE IN Al-Al3TiFGMs FABRICATED BY A CENTRIFUGAL METHOD 渡辺義見、江竜寛之、福井秦好 Yoshimi WATANABE and Hiroyuki ERYU, Yasuyoshi FUKUI "Al-Al3Ti FGMs were fabricated by a centrifugal method with three G numbers, i.e., G=10, 30 and 50. Three types of wear specimens were prepared taking into account the Al3Ti platelet morphology in the thick-walled FGM ring; the Al3Ti platelets were arranged with their platelet planes nearly normal to the radial direction as a result of the applied centrifugal force. A significant anisotropic wear resistance was noted at the ring's outer region whereas anisotropic wear resistance was not observed at the ring's inner region. Based on experimental results, the origin of anisotropic wear resistance in Al-Al3 Ti FGMs is discussed." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 683-689 MoSi2-Mo機能傾斜材料の作製および熱機械的特性 FABRICATION AND THERMOMECHANICAL PROPERTIES OF MoSi2-Mo FUNCTIONALLY GRADED MATERIALS Jae-Ho Jeon, Yoo-Dong Hahn, Zhong-Da Yin Jae-Ho Jeon, Yoo-Dong Hahn, Zhong-Da Yin "For the application of Mo as a structural material in an oxidizing atmosphere, an oxidation-resistant surface layer should be introduced because Mo has poor resistance to oxidation over 700K. When MoSi2 was used as the surface layer, cracks would form due to the difference of thermal expansion coefficient between MoSi2 and Mo. In order to overcome this problem, a functionally graded MoSi2-Mo with varying amounts of these two materials was fabricated by hot pressing at 1650deg.C for 4h at a pressure of 30MPa. The MoSi2-Mo FGM shows excellent heat-resistant and thermal-shock properties when it was evaluated by gas burner heating and acoustic emission test." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 691-698 PSZ/Ni FGMの微細構造の材料特性および熱応力状態に対する影響 MICROSTRUCTURE EFFECTS OF PSZ/Ni FGM UPON MATERIAL PROPERTIES AND THERMAL STRESS CONDITIONS 森谷信一、P. C. Zhai, Q. J Zhang,、新野正之 S. Moriya, P. C. Zhai, Q. J Zhang, M. Niino "Microstructure of PSZ/NiCr FGM fabricated by LPPS (Low Pressure Plasma Splay) method shows a pile of PSZ layers and NiCr layers. On the other hand, a PSZ/NiCr FGM fabricated by a sintering method or an EF (Electro Forming) method has particles dispersion structure. In this paper, finite element analysis was conducted by using microstructure models to study the microstructure effects of PSZ/NiCr FGM upon effective material properties and thermal stress conditions." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 699-704 W-Mo-Ti密度傾斜フライヤープレート材料の準等エントロピ圧縮特性 QUASI-ISENTROPIC COMPRESSION CHARACTERISTICS OF W-Mo-Ti GRADED DENSITY FLIER-PLATE MATERIALS Q. Shen, J. G. Li, C. B. Wang, L. M. Zhang, H. Tan Q. Shen, J. G. Li, C. B. Wang, L. M. Zhang, H. Tan "Quasi-isentropic compression techniques via graded density flier-plate materials, allow investigations of material properties in a high-pressure, low-temperature regime which is inaccessible by conventional shock wave experiments. In this study, quasi-isentropic experiments were performed with a light gas gun and W-Mo-Ti graded density flier-plate materials. The histories of the free surface velocity in targets were measured by VISAR. Effects of density distributions in the flier-plate materials on the wave profiles are discussed. It is found that wave profiles with a smoothly-rising front were created inside the targets, and the maximum pressure peak reached 167GPa. The flier-plates with parabolic distribution of density can produce a better quasi-isentropic compressive wave profile." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 705-712 Cu/Al2O3傾斜機能材料の熱サイクル挙動 THERMAL CYCLING BEHAVIOUR OF A Cu/Al2O3-FUNCTIONALLY GRADED MATERIAL A. Neubrand、 川崎亮、Y. Y. Yang A. Neubrand, A. Kawasaki, Y. Y. Yang "Cu/Al2O3 FGMs were produced by infiltration of Cu into porous graded Al2O3, and their thermal cycling behavior was investigated for two different gradation functions by heating with a H2/O2 flame from the Al2O3 side. At low heat fluxes, cracks perpendicular to the surface were initiated. Critical heat fluxes for surface crack initiation were 1.5-2MW/m**2 with only slight differences between different gradation profiles. At higher heat fluxes additional horizontal cracks were formed at the interface between the ceramic coating and the Cu/Al2O3 composite. The formation of this type of cracks was delayed for a joint with a linearly graded Cu/Al2O3 interlayer compared to a three-layer joint." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 715-722 粘弾性傾斜機能材料の破壊力学 FRACTURE MECHANICS OF VISCOELASTIC FUNCTIONALLY GRADED MATERIALS Glaucio H. Paulino, Z.-H. Jin Glaucio H. Paulino, Z.-H. Jin "In this paper, the basic equations of viscoelasticity in functionally graded materials (FGMs) are formulated. The ""correspondence principle"" is revisited and established for a class of FGMs where the relaxation moduli for shear and dilatation (mu)(x, t) and K(x, t) take separable forms in space and time, i.e. (mu)(x, t)=(mu)0 (mu)'(x) f(t) and K(x, t)=K0K'(x)g(t), respectively, in which x is the position vector, t is the time, (mu)0 and K0 are materials constants, and (mu)'(x), K'(x), f(t) and g(t) are nondimensional functions. The ""correspondence principle"" states that the Laplace transforms of the nonhomogeneous viscoelastic variables can be obtained from the nonhomogeneous elastic variables by replacing (mu)0 and K0 with (mu)0pf'(p) and K0pg'(p), respectively, where f'(p) and g'(p) are the Laplace transforms of f(t) and g(t), respectively, and p is the transformed solution. The ""correspondence principle"" is then applied to a crack in a viscoelastic FGM layer sandwiched between two dissimilar homogeneous viscoelastic layers under antiplane shear conditions. Results for stress intensity factors, including their time evolution, are presented considering the power law material model." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 723-730 傾斜機能層特有の亀裂の応力拡大係数 STRESS INTENSITY FACTORS FOR A CRACK ARBITRARILY ORIENTED IN A FUNCTIONALLY GRADED LAYER Sami El-Borgi, Fazil Erdogan, Lotfi Hidri Sami El-Borgi, Fazil Erdogan, Lotfi Hidri "In this paper, we consider an infinitely long elastic layer made of a Functionally Graded Material (FGM) with an embedded center crack subjected to arbitrary crack surface tractions. The material property grading is assumed to be exponential. Both the direction of material property variation and crack orientation are assumed to be arbitrary. The medium is modeled as a nonhomogeneous elastic solid with an isotropic stress-strain law under plane strain or generalized plane stress conditions. Fourier transforms are used to convert the coupled Naviers equations into a system of singular integral equations with the crack surface displacements as density functions. The integral equations are solved numerically to yield the displacement field in the medium. The primary objective of the paper is to study the effect of the nonhomogeneity parameters and the direction of material property variation on the crack tip stress intensity factors." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 731-738 傾斜機能材料のモードI亀裂の弾性傾斜理論 GRADIENT ELEASTICITY THEORY FOR MODE I CRACK IN FUNCTIONALLY GRADED MATERIALS Youn-Sha Chan, Glaucio H. Paulino, Albert C. Fannjiang Youn-Sha Chan, Glaucio H. Paulino, Albert C. Fannjiang "High-order gradients play an important role in modeling fracture phenomena. Thus, an anisotropic strain-gradient elasticity theory with two characteristic lengths, l and l', associated to volumetric and surface elastic strain energy, respectively, is applied to fracture mechanics. The mode I fracture problem on a half-space is modeled and solved by means of a system of coupled hypersingular integrodifferential equations, which are discretized by means of the collection method. Numerical results include displacement profiles and the stress intensity factors (SIFs) corresponding to various material parameters." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 739-746 傾斜機能材料の亀裂および接触問題 CRACK AND CONTACT PROBLEMS IN FUNCTIONALLY GRADED MATERIALS F. Erdogan and S. Dag F. Erdogan and S. Dag In this article the failure of FGM substrates due to sliding contact is considered. The first stage of the failure process involves crack initiation on the surface of FGM substrates or FGM coatings bonded to homogeneous substrates caused by the tensile stress due to friction forces. The second stage is the crack propagation under repeated loading. After a brief review of the related contact problem leading to the calculation of complete stress state on the surface, the coupled crack-contact problem for an FGM substrate loaded by a rigid stamp is considered and the stress intensity factors are calculated. English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 747-754 亀裂の生じた傾斜機能材料の非定常熱応力 TRANSIENT THERMAL STRESS ANALYSIS OF CRACKED FUNCTIONALLY GRADED MATERIALS Z.-H. Jin, Glaucio H. Paulino Z.-H. Jin, Glaucio H. Paulino "An edge crack in a strip of a functionally graded material (FGM) is studied under transient thermal loading conditions. The FGM is assumed having constant Young's modulus and Poisson's ratio, but the thermal properties of the material vary along the thickness direction of the strip. Thus the material is elastically homogeneous but thermally non-homogeneous. This kind of FGMs include some ceramic/ceramic FGMs such as TiC/SiC and MoSi2/Al2O3, and also some ceramic/metal FGMs such as zirconia/nickel and zirconia/steel. A multi-layered material model is used to solve the temperature field. By using the Laplace transform and an asymptotic analysis, and analytical first order temperature solution for short times is obtained. Thermal stress intensity factors (TSIFs) are calculated for a TiC/SiC FGM with various volume fraction profiles of the constituent materials. It is found that the TSIF could be reduced if the thermally shocked cracked edge of the FGM strip is pure TiC." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 755-762 傾斜機能媒体の部分的に離れた亀裂の熱機械応力拡大係数 THERMO-MECHANICAL STRESS INTENSITY FACTORS FOR A PARTIALLY INSULATED CRACK IN A FUNCTIONALLY GRADED MEDIUM Sami El-Borgi, Fazil Erdogan, Houda Hila, Hichem Smaoui Sami El-Borgi, Fazil Erdogan, Houda Hila, Hichem Smaoui "In high-temperature applications, the materials research community has been recently exploring the possibility of using new nonhomogeneous coatings made of Functionally Graded Materials (FGMs) as an alternative to the conventional homogeneous ceramic coatings. In designing components involving FGMs, an important aspect of the problem is the fracture failure. In this paper, we consider an infinite medium made of a Functionally Graded Material (FGM) with a partially insulated crack subjected to a steady- state heat flux at infinity as well as mechanical stresses. The problem is modeled as a nonhomogeneous elastic medium with an isotropic stress-strain law under the assumption of plane strain or generalized plane stress conditions. The heat conduction and the plane elasticity partial differential equations are converted analytically into singular integral equations which are solved numerically. The equivalent thermal stresses to be applied as crack surface tractions are also obtained. The main objective of the paper is to study the effect of the material nonhomogeneity parameters and the partial crack surface insulation on the crack tip stress intensity factors for the purpose of gaining better understanding on the behavior and design of graded materials." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 763-770 傾斜機能構造をもつ三角棒のねじれに関する問題 TORSIONAL PROBLEM OF TRIANGULAR BAR WITH FUNCTIONALLY GRADED STRUCTURE 天田重庚、寺内奏 Shigeyasu Amada, Yasushi Terauchi Hemp palm branches have a triangular cross section which is very exceptional and a functionally graded structure for the reinforced fiber distribution. The fiber distributes densely in the outer surface layer and sparsely in the core region. This is modeled by a three layered composite bar with a triangular cross section. A torsional problem of this bar is solved using conformal mapping and complex torsional function approach and an analytical solution is derived in terms of complex power series. The computed maximum shear stress is reduced compared to the stress in the homogeneous bar. This reduction rate increases with the difference of both the shear modulus of the core and outer layer. Under the twisting moment the induced shear stress distribution is similar to the fiber distribution with the functionally graded structure. It was concluded that this structure like the Hemp palm branch is more adapted to the environmental loading than a homogeneous structure. English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 773-780 微細構造傾斜を持つノッチ付きパーツの破損 FRACTURE IN NOTCHED PARTS WITH A MICROSTRUCTURAL GRADIENT F. Bohner, J. K. Gregory F. Bohner, J. K. Gregory "Notched parts are subjected to loading or stress gradients, hence, it makes sense to tailor the local strength to this profile by generating an appropriate microstructural gradient. This was achieved in the age-hardenable alloys Ti-2.5Cu and 2017 Al by thermomechanical surface treatment. While the macroscopic yield stress in graded notched specimens can be reliably evaluated and reasonably well predicted using a simple local strength approach, and appropriate choice of specimen geometry is apparently critical to adequately assess fracture toughness. In contrast to the tensile behavior, no effect of the gradation on fracture properties is observed." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 781-788 アルミナジルコニア傾斜複合材におけるRカーブ挙動の重み関数解析 A WEIGHT FUNCTION ANALYSIS OF R-CURVE BEHAVIOR IN GRADIENT ALUMINA-ZIRCONIA COMPOSITES Robert Moon and Mark Hoffman, Juegen Roedel, Jon Hilden, William Blanton, Keith Bowman, Kevin Trumble Robert Moon and Mark Hoffman, Juegen Roedel, Jon Hilden, William Blanton, Keith Bowman, Kevin Trumble "The single-edge-V-notched-beam (SEVNB) testing geometry was used to measure the crack growth resistance (R-curve) behavior of gradient multilayer alumina-zirconia composites. Fracture mechanics weight function analysis was applied to estimate the change in the apparent fracture toughness as a function of notch position, resulting from residual thermal stress distributions. These results were then used to differentiate the influence of residual stress from other closure stresses attributed to crack bridging on the measured R-curve behavior." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 789-796 Al2O3/Al FGMの破壊靭性およびRカーブ挙動 FRACTURE TOUGHNESS AND R-CURVE BEHAVIOR OF Al2O3/Al FGMs T.-J. Chung, A. Neubrand, J. Roedel, T. Fett T.-J. Chung, A. Neubrand, J. Roedel, T. Fett "Quantitative determination of fracture toughness and R-Curve behavior in FGMs is still an issue as a precise determination of the stress intensity factor in FGMs is not straightforward due to the spatial variation in elastic properties. In the present work it is demonstrated that the weight function method can be adapted to FGMs. Fully dens Al2O3/Al FGM compact tension specimens with different well controlled gradients in the direction of crack propagation were prepared by an infiltration technique, and experimental data for the R-curve behavior of the different Al2O3/Al FGMs were determined." English Functionally Graded Materials 2000 Functionally Graded Materials 2000 21 2000-09-10 797-804 延性/脆性傾斜複合材の破損 FRACTURE IN DUCTILE/ BRITTLE GRADED COMPOSITES Jesus Chapa, Keith Rozenburg, Ivar Reimanis, Eric D. Steffler Jesus Chapa, Keith Rozenburg, Ivar Reimanis, Eric D. Steffler "Experiments in conjunction with finite element analysis (FEA) were used to better understand the crack propagation in ductile/brittle graded composites. Graded Cu/W composites were fabricated by stacking discrete layers and hot pressing. Notches were cut perpendicular to the gradient on different composition layers. Experiments show that the gradient in material properties shifts the phase angle of loading, which cause the crack to deflect. Moire interferometry and FEA are used to assess the relative influence of elastic-plastic gradient and thermal residual stresses on the phase angle. FEA and experimental results suggest that the elastic-plastic gradient has the largest effect on shifting the phase angle." English