X-RAY MEASUREMENT OF STRESSES IN DEPOSITED THIN FILM WITH FIBER TEXTURE
Takao HANABUSA
Review Paper (Vol.5 No.2)
X-RAY MEASUREMENT OF STRESSES IN DEPOSITED THIN FILM WITH FIBER TEXTURE |
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Takao HANABUSA |
63 |
General Papers (Vol.5 No.2)
EFFECTS OF FIBER LENGTH AND ORIENTATION DISTRIBUTIONS ON THE MECHANICAL PROPERTIES OF SHORT-FIBER-REINFORCED POLYMERS |
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Shao-Yun FU, Xiao HU and Chee-Yoon YUE |
74 |
PROCESSING AND MECHANICAL PROPERTIES OF Si3N4/Sic NANOCOMPOSITES USING Si NITRIDED Si3N4 POWDER |
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Jian-Feng YANG, Tohru SEKINO, Yong-Ho CHOA and Koichi NIIHARA |
84 |
ESTIMATION OF TENSILE STRENGTH DISTRIBUTION FOR CARBON FIBER WITH DIAMETER VARIATION ALONG FIBER |
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Tsuneshichi TANAKA, Hideaki NAKAYAMA, Akiyoshi SAKAIDA and Noriyo HORIKAWA |
90 |
RATE-DEPENDENT MODE II INTERLAMINAR FRACTURE BEHAVIOR OF CARBON-FIBER/EPOXY COMPOSITE LAMINATES |
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Takayuki KUSAKA, Masaki HOJO, Shojiro OCHIAI and Tomoaki KUROKAWA |
98 |
EFFECTS OF WINDING PROCESS VARIABLES ON TENSILE PROPERTIES OF FILAMENT WOUND STRUCTURES USING SPLIT DISK TEST |
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Sung-Ho YooN and Jun-Young KiM |
104 |
MAGNETIC PROPERTIES AND ELECTRON SPIN RESONANCE OF CARBON FINE PARTICLES PREPARED IN He PLASMA |
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Shin AKUTSU and Yoshio UTSUSHIKAWA |
110 |
EFFECTS OF YTTRIUM AND SODIUM ADDITION ON PREPARATION AND HUMIDITY SENSITIVITY OF POROUS APATITE CERAMICS |
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Masafumi KOBUNE, Hiromi IIDA, Yoshiaki SORAI, Atsushi MINESHIGE, Satoshi FUJII and Nava SETTER |
116 |
MULTI-MODAL VIBRATION CONTROL OF SMART COMPOSITE PLATES |
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Jae-Hung HAN, Junji TANI and In LEE |
122 |
Short comunication (Vol.5 No.2)
DIAMAGNETIC CHARACTERISTICS FEATURED BY CRITICAL CONCENTRATION OF Pr IN y1-xPrxBa2Cu3O7-s | |
Katsukuni YOSHIDA and Tomohiro GOYA |
128 |
Vol.5 No.2 ABSTRACT
X-RAY MEASUREMENT OF STRESSES IN DEPOSITED THIN FILM WITH FIBER TEXTURE
Takao HANABUSA
Abstract:Thin film coating by physical vapor deposition (PW) and chemical vapor deposition (CVD) techniques are advancing intensively in the technology of mechanical as well as electrical fields. Deposition by these techniques essentially develops residual stresses in the film for intrinsic and extrinsic reasons. The microstructure of the film normally exhibits a strong preferred orientation on a crystallographic scale. Residual stresses and the microstructure of the growing film influence the properties of the film as well as the film/substrate system. The present paper demonstrated the recent developments in X-ray stress evaluation of the film having a very sharp preferred orientation. A new method of X-ray stress measurement for such films having a strong texture is presented in place of the conventional sin2 y method. C-axis oriented aluminum nitride (AlN) films, [111] fiber textured aluminum and titanium nitride (TiN) films and [110] fiber textured TiN films are investigated to study the residual stress and the effect of heat treatment on the state of residual stress. The effects of patterning the film on residual stress are also investigated. Key Words:X-ray stress measurement, Thin film, Residual stress, Thermal stress, c-axis orientation, Fiber texture, AlN film, Al film, TiN film
Shao-Yun FU, Xiao HU and Chee-Yoon YUE
Abstract:Extrusion compounding and injection molding processes are frequently employed to fabricate short-fiber-reinforced polymers. During extrusion compounding and injection molding processing, considerable shear-induced fiber breakage takes place and results in a fiber length distribution (FLD) in final short-fiber-reinforced polymer (SFRP) composites. Also, during compounding and molding processing, progressive and continuous changes in fiber orientation occur and lead to a fiber orientation distribution (POD) in final composites. Both FLD and POD are governed by a number of design and fabrication factors including original fiber length, fiber content, mold geometry and processing conditions. The mechanical properties such as strength, stiffness and fracture toughness or specific work of fracture (WOF) of SFRP composites have been shown to depend critically on FLD and POD. The present paper reviews previous research work on the effects of design/fabrication factors on FLD and POD and the effects of FLD and POD on the strength, stiffness and toughness or WOF of SFRP composites. Conclusions which can be drawn from the literature are presented with discussions of areas in which further research is required. Key Words:Short-fiber-reinforced polymer (SFRP) composites, Strength. Stiffness, Toughness/specific work of fracture, Fiber length distribution, Fiber orientation distribution
PROCESSING AND MECHANICAL PROPERTIES OF Si3N4/Sic NANOCOMPOSITES USING Si NITRIDED Si3N4 POWDER
Jian-Feng YANG, Tohru SEKINO, Yong-Ho CHOA and Koichi NIIHARA
Abstract:The pressureless sintering was investigated to fabricate dense Si3N4/Sic nanocomposites from commercially available Si nitrided Si3N4 powder. MgAl2O4 + ZrO2 (totally 10 and 15 wt%) or Y2O3 + Al2O3 (totally 10.5 and 14 wt%) and 5-30 vol% SiC were used as sintering additives and second phase dispersions, respectively. With increasing SiC content, the density of the composite containing less amount of sintering additives decreased linearly, while the large amount of sintering additives decreased gradually the density or kept it constant. The composites with higher SiC content presented a relatively smaller Si3N4 grain size, because the Si3N4 grain growth was inhibited by SiC particles that pinned the grain boundary movement. While decrease in strength was observed for the composites with less amount of sintering additives, an improvement of the strength was found for the composites with high amount of sintering additives. The strength change of the composites was consistent with their densification behavior and microstructural observation. Composite with 20 vol%, SiC exhibited high strength up to 1 GPa. With increasing SiC content, hardness increased but toughness decreased. It is concluded that the results of this study provide an economic way to fabricate the Si3N4/SiC nanocomposite with high performance. Key Words:Silicon nitride, Silicon carbide, Nanocomposite, Densification, Mechanical properties
ESTIMATION OF TENSILE STRENGTH DISTRIBUTION FOR CARBON FIBER WITH DIAMETER VARIATION ALONG FIBER
Tsuneshichi TANAKA, Hideaki NAKAYAMA, Akiyoshi SAKAIDA and Noriyo HORIKAWA
Abstract:Tensile strength distribution of carbon fibers was investigated for different gauge lengths ranging from 2 to 100 mm. In tensile tests, the fiber diameter was determined as the three-point minimum diameter d3 at neighborhoods of both ends and the center of gauge section by using an optical microscope. Weibull analysis of the data and the effective volume model for tensile strength of carbon fiber showed that the shape parameter a was not constant for different gauge lengths and the effective volume model could not be applied effectively to the results. It was found that these were caused by the fact that the diameter was never constant along a carbon fiber. Consequently, in this study, it was aimed to derive the distribution of the tensile strength Jo for the true minimum diameter do along the gauge length. In order to do this, two-dimensional distributions of d3 and do were derived from the data of diameter measured at every 0.1 mm along a single fiber with the gauge length of 100 mm. Combining these distributions of d3 and do with the distribution of the tensile strength s3 for the diameter d3, the distribution of the strength Jo Was derived analytically, and calculated by using numerical values of included parameters. The distributions of ??sigma o obtained for respective gauge lengths mutually agreed very well and could be represented by a single normal distribution, and this showed the validity of the present analysis. Key Words:Carbon fiber, Tensile test, Tensile strength, Weibull analysis, Effective volume, Size effect
RATE-DEPENDENT MODE II INTERLAMINAR FRACTURE BEHAVIOR OF CARBON-FIBER/EPOXY COMPOSITE LAMINATES
Takayuki KUSAKA, Masaki HOJO, Shojiro OCHIAI and Tomoaki KUROKAWA
Abstract:Effects of loading rate on mode II interlaminar fracture behavior of unidirectional CF/conventional-epoxy (T300/2500, Toray) and CF/toughened-epoxy (IM600/133, Toho Rayon) composite laminates were investigated over a wide range of loading rate from quasi-static to impact at room temperature (displacement rate, = 10-7-101 m/s). A newly developed experimental method using the SHPB (Split Hopkinson Pressure Bar) technique and the ENF (End Notched Flexure) specimen was employed for measuring the accurate fracture toughness at very high loading rates. The mode II fracture toughness at the onset of crack growth showed positive rate dependence (fracture toughness increased with increasing loading rate) at lower loading rates, while it showed negative rate dependence (fracture toughness decreased with increasing loading rate) at higher loading rates; there existed a local maximum value of fracture toughness at intermediate loading rates. The impact fracture toughness was about 13 and 29 % lower than the local maximum value for the conventional epoxy composite and toughened epoxy composite, respectively; the toughened epoxy composite was more sensitive to the loading rate than the conventional epoxy composite. Microscopic observation showed that the debonding of fiber/matrix interface was dominant at lower loading rates and that the cohesive fracture of matrix resin was dominant at higher loading rates. The transition point of microscopic fracture morphology approximately coincided with the local maximum point of macroscopic fracture toughness. In addition, the load-displacement relation was non-linear just before the onset of crack growth at lower loading rates but almost linear up to the maximum point at higher loading rates. Key Words:CFRP, Delamination, Fracture toughness, Fracture morphology, Mode E, Rate dependence, Impact strength, Toughened composite
Sung-Ho YooN and Jun-Young KiM
Abstract:The effects of the winding process variables on the tensile properties of the filament wound structures were investigated. The ring specimens, consisted of the carbon fiber as reinforcement and the epoxy as resin, were fabricated through the filament winding technique for the measurement of the tensile properties・. The fiber tensions and the fiber ends were considered as the winding process variables・ The fiber tensions per fiber bundle varied from 4・9 N to 29・4 N・ The fiber ends varied from 1 end to 6 ends. The tensile properties of the ring specimens were evaluated through the split disk test. The fiber volume fractions and the void contents for the ring specimens were also measured by the resin digestion. According to the results, the tensile properties of the ring specimens were sensitive to the fiber tensions and the fiber ends, which were closely related to the fiber volume fractions and the void contents. Therefore, the suitable selection for the winding process variables should be conducted to maximize the structural performance and to increase the productivity of the filament wound structures. Key Words:Filament wound structures, Winding process variables, Tensile properties, Fiber tensions, Fiber ends, Split disk test, Fiber volume fractions, Void contents, Resin digestion
MAGNETIC PROPERTIES AND ELECTRON SPIN RESONANCE OF CARBON FINE PARTICLES PREPARED IN He PLASMA
Shin AKUTSU and Yoshio UTSUSHIKAWA
Abstract:In this study, we examined the correlation among the crystal structure, the unpaired electron, and the magnetism of carbon fine particles. From the result of X-ray diffraction, it is determined that the saturation magnetization of the carbon fine particles is influenced by degree of crystallinity, when die degree of crystallinity is 3.62 %. The saturation magnetization is 8.5 X 10-7 Wbm/kg. The saturation magnetization of carbon fine particles increases with decreasing grain six, and the grain sin of the carbon fine particles having the highest Ms of 8.5 X 10-7 Wbm/kg is l9 mm. From the ESR spectrum the g-factor of the carbon fine particles is found to be 2.0023. The magnetism of carbon fine particles may be due to the electron spin. Electron spin density of the carbon fine particles is 1.6 X 1022kg-1 and it is observed that the electron spin density increases by 1.5 times as compared with graphite. From the temperature dependence of ESR, it is found that the linewidth of the ESR increased with decreasing temperature, and the spin-spin relation time T2 decreased with decreasing temperature. Key Words:Carbon fine particles, Graphite, He plasma, Magnetism, Saturation magnetization, X-ray diffraction, Degree of crystallinity, Grain size, Electron spin resonance, g-factor.
Masafumi KOBUNE, Hiromi IIDA, Yoshiaki SORAI, Atsushi MINESHIGE, Satoshi FUJII and Nava SETTER
Abstract:Sodium yttrium calcium-oxyhydroxyapatites powders with compositions of {[Ca9.98-0.9xY0.9xNa0.02](PO4)6[OH]1.98-0.9zO0.9x□0.02},x=0-1.0(here □ denotes vacancies at OH lattice sites) were synthesized by the wet process. Porous (Ca, Y, Na)-Ap (here Ap denotes apatite) ceramics having apparent porosities of around 33 % were prepared at high temperature under steam flow. On the basis of the results of X-ray diffraction, all the obtained ceramics exhibited almost single-phase (Ca, Y, Na)-Ap with hexagonal structure. The impedance for all samples linearly changed from 106 to 104 ??(オーム) s at 50 deg. in the humidity range of 40 - 95 %RH. Apatites produced by substituting Y3+ and Na+ for Ca2+ in apatite structure showed an excellent conductivity. This is attributed to both ordinary protonic conduction caused by the self-dissociation of physically adsorbed water and another conduction caused by OH vacancies introduced by substituting Y3+ and Na+ fur Ca-sites. Key Words:Humidity sensor, Humidity sensitivity, Calcium oxyhydroxyapatite, Wet process, Impedance, Yttrium, Sodium, Porous ceramics
MULTI-MODAL VIBRATION CONTROL OF SMART COMPOSITE PLATES
Jae-Hung HAN, Junji TANI and In LEE
Abstract:In this paper, multi-modal vibration control of smart composite plates has been studied. Piezoelectric films and ceramics have been used as sensors and actuators in surface bonded forms. For modeling and analysis of smart composite plates, an efficient finite element method based on the layerwise plate theory has been used. The effect of thickness changes due to bonded piezoelectric materials and variable in-plane displacement fields on the dynamic, actuating and sensing characteristics have been considered in the finite element formulation. This study includes an optimization method based on genetic algorithms to select appropriate locations of piezoelectric sensors and actuators of a smart composite plate for maximization of control performance. The cost function used in the optimization is based on degrees of controllability, observability, and spillover prevention. Experimental multi-modal vibration control has been also performed. A smart composite plate is prepared according to the optimization results for the experimental works. Coupled positive position feedback algorithms have been implemented in digital signal processing (DSP) system. The control results show that vibration level of the controlled modes has been significantly reduced with negligible effect on the residual modes. Key Words:Smart materials and structures, Finite element method, Multi-modal vibration control, Sensor/Actuator placement, Positive position feedback