This paper investigates the stress relief patterns of diamond carbon coatings on silicon mono-crystal by atomistic simulation method. It was found that the nature of the buckling patterns varied with the crystal orientation and the ratio of the residual stresses in the two directions. A telephone-cord like buckling mode took place on the Si (100) surface when the residual stresses were biaxially equal and this is similar to what was observed in micro-scale experiments.

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We have developed a 3-6μm thin-film pressure sensor using the piezo-resistive effect of Cu-Mn-Ni alloys in order to measure the oil-film pressure in the plane bearing of the internal combustion engine. This sensor can be deposited 3-6μm in thickness directly on the bearing surface using the PVD (RF magnetron sputtering) method without changing the shape of the sliding surface or reducing the rigidity of bearing housing, caused by making a hole for sensor installation in the bearing housing. On the other hand, one of the problems with this sensor is low durability. In order to improve the sensor durability, we have deposited and evaluated the diamond-like carbon (DLC) as the material for the insulation and protection films of the sensor. Although we succeeded in fabricating a DLC film of high insulation resistance by using DC magnetron sputtering, the DLC film showed low adhesion strength on the sensor alloys such as Cu alloys and Ni-Cr alloys. In the next step, we tried to deposit the aluminum oxide film by using the RF magnetron sputtering method enhanced with inductivity-coupled plasma. As the result of scratch test, the thin-film, deposited by above new sputtering method, showed a high critical load (Lc), compared with the films deposited by the conventional RF magnetron sputtering. This film provided a sufficiently high adhesive strength to the sensor alloys.

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The aim is to research the frictional properties of TiN coatings with the preferred orientation of grains controlled by changing the substrate bias voltage. TiN coatings are deposited on the substrate (SKD11) by PVD arc ion plating process. In these experiments, the substrate bias voltage is varied in the range of -20 to -200V. With increasing bias voltage, the preferred orientation of grains change from (200) orientation produced at -20 and -50V to (111) orientation produced at -100,-150 and -200V. After the deposition by PVD process, the coefficient of friction are measured by ball-on-disc tester. The results obtained by ball-on-disc test show that the specimens coated at -150 and -200V have better tribological properties than those at -20 and -50V. These differences are due to the difference of adhesion force between the coated disc and the ball. It is found that tribological properties of TiN coatings depend on the preferred orientation of grains controlled by changing the substrate bias voltage.

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The scanning probe microscopy (SPM) is still suffering from the reproducible fabrication of the corresponding sensors for the mechanical, electrical, optical, thermal and chemical material characterisation with highest lateral and/or time resolution. For this batch fabrication technique lithographic, dry etching and material problems have to be solved. Using this techniques several types of cantilevers and tips including piezoresistive detection systems have been performed world wide for the first time.

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Rapid prototyping (RP) has been used for design verification and proto sample or mold manufacturing. Many RP systems have been introduced into the market during the past 15 years. However, until now, the systems have used mainly for external physical models (mono function), and have the basic but critical limitation of one material on one stage (mono material). To overcome the limitations of mono-material and mono-function of conventional RP systems, the concept of Functional Prototype Development (FPD) is newly proposed in this paper. FRD provides the necessary prototype functions such as mechanical, optical, chemical and electrical properties in order to meet the broad requirements of the industry. The paper illustrates the representative achievements of electronic components such as inner visible multi color prototype and the multi-layer printed circuit board (MLB). Experimental results demonstrate that FPD has great potential applied to broad industrial uses and that it will be a powerful tool in the near future.

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We report a novel method for nanomechanical characterization and Young's modulus determination of a nanosize silicon (100) tip cutting tool. These tools (aspect ratio >1 : 10) are shaped using focused ion beam (FIB) machining. Currently, we are developing a novel nanometer-scale mechanical machining system-on-a-chip (SOAC) based on these tools. Thus, proper characterization of their mechanical properties is of significant importance for top-down nanomanufacturing. Real time imaging of the controlled bending of this nano tool was performed in situ in the transmission electron microscope (TEM) utilizing a unique piezo-controlled in-situ indenter. Nanomechanical analysis was performed by coupling video frames of the bending behavior with calibrated voltage data from piezo crystal. This permits direct determination of the Young's modulus of the nano tool. Nanomechanical analysis was also performed using finite element analysis (FEA).

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Development a machining method for single crystal diamonds has been investigated, as a result of the intense need of 3-D shapes of diamond. This processing method is achieved through utilization of diamond graphitization and tool wear of diamond during the cutting process of carbon steel. A three-dimensional shape of diamond has been successfully obtained by this machining method. In this study, a comparison has conducted among the present cutting method and other processing methods. At first, the present method is compared with a YAG laser machining; the diamond surface after machining by present method is much better than that by YAG laser machining method. Next, the present method is compared with other methods that utilize the affinity between diamond and ferrous material, using only heating or rubbing. The removal rate of diamond in cutting technique of this research is considerably higher and efficient than other methods. Some samples of the machined diamond by present method are shown in the end of this paper.

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This paper describes a new method of surface modification by EDM to create a hard surface on a workpiece. When a metallic material that makes a hard carbide is used as an electrode in EDM, a hard layer can be made under certain conditions. The process begins with electrode wear by heat of EDM. Then the worn electrode material becomes a hard carbide. The carbide piles up on the workpiece and becomes a layer. A layer formed by two or more electrical discharges has the problem that the performance of the layer, its roughness and hardness, is not enough. In this paper, the relation between the gap width and layer performance is discussed in order to improve the layer performance. First, the results of experiments on single electrical discharge are shown. Then the results of this surface modification (EDC) is shown.

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Electrochemical machining has been increasingly recognized for the potential for micromachining. A process to erode a hole of hundreds of micronmeters on the metal surface is analyzed in the current paper. The precision of the machined geometry is a concern of the application of the micro-ECM. The purpose of this study is to predict the profile development of the machined surface under the applied tool electrode during the process. A theoretical and computational model is presented to illustrate how the machined profile evolves as the time elapses. The analysis is based on the fundamental law of electrolysis and the integral for a finite-width tool. The validity of the model is examined by experiments.

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Micro mechanical machining technology has been studied for fabricating smaller size structures and enhancing form accuracy. The dimensions of structures are generally determined by the size of the micro mechanical tool. However, the size of the mechanical tool is limited by the mechanical properties of the tool, such as elasticity limit, yield strength, and fracture and buckle that is caused by the machining resistance force. To overcome these drawbacks and enhance the surface quality and form accuracy in mechanical micro machining, this paper proposes a new method of micro machining with the aid of chemical solutions. The chemically reacted layer on the substrate is thought to restrict the plastic deformation of work material. As a result, it is expected to have the lower machining force, tool wear reduction and high form accuracy compared to other methods. In this study, we carried out an experiment on both the brittle and ductile material.

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We investigated macroscopic and microscopic deformation of optical glasses K-PSK100 and K-PG375 for precision molding. The materials are characterized by a low glass transition temperature T_g; T_g is 663K for PSK100 and 616K for PG375. The materials exhibit Newtonian viscous flow above T_g. We studied the temperature dependence of the normal viscosity and evaluated the microformability by the geometrical transferability of a V-grooved die shape to the material. The dies were made of (100) Si and the width of the V-groove W_g was 0.1 to 2.0 micrometers. After die-forming, we measured the transferred shape of the material with AFM and analyzed the curvature ρ of the tip of the deformed specimen and the formed and filled area to the V-groove R_f. As a result, we found that the materials exhibit superior microformability due to the homogeneity on a nanometer scale and will be applied to micro-or nanoforming and thus contribute to mass production of micro/nano-devices.

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Material length scales expressed in terms of strain gradients have been successfully incorporated into constitutive models to explain the size-effect in indentation, bending and torsion. Deformation in machining involves large strain gradients and is known to demonstrate a comparatively larger size-effect. This paper attempts to explain the size-effect in the Primary Deformation Zone (PDZ) of an orthogonal cutting process by developing a strain gradient plasticity based model. Considering a parallel-sided configuration of the PDZ, models are formulated for the strain gradient, density of geometrically necessary dislocations, shear strength and the specific shear energy. The analysis shows that for deformation in the PDZ, the length of the shear plane represents the material length scale. The model also provides an estimate of the lower bound on the size-effect observed in the specific shear energy. Trends in the predicted specific shear energy match well with the experimental values obtained from the literature.

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A miniaturized machine tool-referred to as Micro/Meso-Scale Machine Tool (mMT)-is studied by the characterization of structural dynamics in this paper. The scaling effect of the dynamics of machine structures of a conventional machine tool and the prototype of a mMT is investigated through the finite element analysis (FEA) and the experimental modal analysis. The results of experimental modal analysis reveal that the fundamental natural frequency of the prototype of mMT (148.6 Hz) is much lower than that obtained by the dynamic scaling analysis via FEA (250 Hz approximately). The effect of joint conditions between machine components on the dynamic behaviors of the machine structure is shown to be a significant factor.

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A combined experimental and modeling (both numerical and analytical) approach has been devised to understand the material removal mechanism during abrasion of ductile copper discs. First, single grit scratch intersection experiments are conducted at the micro-scale (with 1-30μm depth of cut). This is followed by FEM analysis. Then a simple analytical model is developed, and the model prediction is verified against experimental observations and results from numerical simulations. The insights gained from this exercise may be used to develop a mechanistic model of material removal in chemical mechanical polishing (CMP) of ductile materials.

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Solidification of 285 μm mono-size copper droplets, produced by controlled laminar-jet breakup, in nitrogen and helium gas and subsequently in oil was investigated. Oxygen content was maintained at 23 or 203 ppm in the nitrogen atmosphere and at 4 ppm in the helium atmosphere. Droplets generated in nitrogen with 203 ppm oxygen solidified into nearly spherical mono-size balls. Droplets generated in nitrogen with 23 ppm oxygen solidified into mono-size balls with poor sphericity and severe surface shrinkage. Droplets generated in helium solidified into mono-size balls with high sphericity and smooth surface. Surface shrinkage was caused by thermal dendritic solidification. A droplet solidification simulation model predicts that spherical balls with good surface are obtained under solidification conditions that permit sufficient liquid redistribution in the solidifying droplets. Controlled laminar jet breakup offers an economical means for the production of mono-size copper balls that are potentially applicable to electronics packaging.

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Composite materials structures often have weaknesses at the location where the materials join, where different materials are placed in proximity or bonded. These weaknesses, flaws or defects control the ultimate strength of the materials. Coupling agents are used to bond disparate materials into one coherent composite. Usually fibers and sometimes beads are part of the composite design. The goal of this area of research has been to develop composites with unique toughness and strength by self repair which occurs at material interfaces and at damaged areas. This is not by the usual methods of hand repair but release of repair chemicals from within the composite itself. These take the form of hollow structural fibers or beads are embedded in the matrix, or a matrix which reacts with the environment itself. The chemicals carried in the hollow vessels are released wherever and whenever cracking or other matrix damage occurs. In the case where the matrix repairs itself this can be due to the interaction of the polymer with the matrix this can be due to interaction with a gas as CO2 or other reactants from the environment and this works most effectively if supplied all through the volume. Chemicals can be designed to reaction and repair more than once. Living polymers and step wise polymerization can carry on more than one reaction per chemical participant. Superior performance over the life of the composite is achieved by the self-repairing and regenerating nature of the interface between the materials. Research to assess and clarify the impact of the various factors involved in self-repair in a more scientific way has been done by Professor Dry who invented the field and holds the basic patents in the area. Repair efficacy of the various applications by other researchers covers a large data field. Due to a lack of clear understanding of the impact of the various factors as well as lack of proper design of all the factors from the start there is a large need for scientific understanding in this area. This research addressed some of these issues by quantifying, relating and explaining the impact of the various factors on each other. These factors are 1) parameter choices such as delivery vessel, shape/size, coating, chemicals released, release trigger and efficacy, impact on matrix properties 2) influence of end use such as the importance of speed and force of release in airplane skin repair and the importance of damping and stiffening chemicals and their set time on bridges subjected to earthquakes 3) combination with various processing methods, focus on resin molding and pultrusion as representative processes with heat and pressure. The objective of the paper is to explain the science issues involved in creating polymer composites designed to be self-repairing.

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In austenitic stainless steels, creep cavities nucleate at grain boundaries by long time use at high temperatures. These creep cavities grow along grain boundaries, form grain boundary cracks by linking up each other and cause the premature and low ductility fracture. Therefore long time creep rupture life and ductilities chiefly depend upon the behavior of nucleation and growth of creep cavities. If the growth of creep cavities could be suppressed, creep rupture life and ductilities should be improved remarkably. Present work is intended to propose a self-healing process for the cavitation and improve the creep rupture properties due to the suppression of creep cavity growth by a self-healing process. Ordinary austenitic stainless steels contain sulfur as impurity and segregates to creep cavity surface because of its high surface activity. It is possible to remove sulfur almost completely by doping cerium and adding titanium to the austenitic stainless steels. By adding boron and nitrogen, boronnitride precipitates on creep cavity surface. It was thought that the boronnitride on creep cavity surface supresses creep cavity growth and improves creep rupture life and ductilities by its healing effect on creep cavities.

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Suppression of stress intensity in crack tip vicinity under mixed mode by using active enhancement in shape memory alloy hybrid composite was presented in this research. Shape memory alloy (SMA) TiNi fiber reinforced epoxy composite were fabricated and its material and mechanical properties were investigated by photoelastic examinations. The stress intensity at crack tip zone were obtained using photoelastic method and the decrease of stress intensity factor K_I and K_II under mixed mode resulted from recovery force when the temperature is over by heating over A_f temperature were examined. The relationship of stress intensity decrease with the pre-strain in SMA fiber and the ambient temperature in isothermal furnace were clarified. On this basis, the active control for stress intensity in shape memory composite was discussed.

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Mechanically fastened joints are widely used for composite structures. Damage in bolted joints occurs by bearing load. It is difficult to detect the bearing failure using conventional nondestructive inspection methods, such as C-scan and X-ray inspection, because laps and washers hide the bearing failure area. Additionally these nondestructive inspection procedures are usually expensive, cumbersome, and time-consuming. In order to detect the bearing failure easily, the electric resistance change method is applied to bolted composite joints. Since a carbon fiber reinforced composite has strong anisotropy of electric resistance, electrodes are mountable away from holes. The electric resistance change alarms occurrence of the bearing failure at the hole. In this study, the electric resistance changes are measured experimentally during the tensile tests. The failure propagation is observed by a microscope and C-scan inspection. As a result, it is shown that the bearing failure of bolted composite joints is detectable by the proposed method.

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The mathematical modeling of smart composite structures is a rather convoluted task due to the anisotropic nature of the host composite material and the contribution of the integrated sensors and actuators. Therefore special analytical techniques should be developed and applied to the analysis of these structures. In this work, the method of asymptotic homogenization is used to derive micromechanical models pertinent to smart composite materials with a regular structure, and subsequently to determine effective elastic, actuation and thermal expansion coefficients. The actuation coefficients characterize the intrinsic transducer nature of smart materials that can be used to induce strains and stresses in a controlled manner. The general model is applied to a practically important case of a laminated smart material with piezoelectric actuators. Analytical formulae for the effective stiffnesses and piezoelectric coefficients are obtained explicitly. The effectiveness of the derived model is illustrated by means of two-and three-dimensional examples.

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An active composite beam (ACB) with surface-mounted piezoelectric ACX and two embedded CCC has been modeled. The ACX piezoelectric patch acts as a shaker and the two CCC piezoelectric patches act one as a sensor and the other as an actuator. This new model has been developed for the verification of the four direct vibration suppression schemes, namely Constant Voltage (CV), Optimum Voltage (OV), Corresponding Voltage (COV), and Truncated Corresponding Voltage (TCOV) scheme introduced earlier by the authors. The ACX piezoelectric with dimensions of 51x38x0.50 mm is surface-mounted near the clamped end of the beam. The two CCC piezoelectric patches with dimensions of 135x55x0.33 mm are embedded one near the clamped end and the other near the tip. The CCC piezoelectric patch embedded at the tip of the beam acts as a sensor and the one embedded near the clamped end acts as an actuator. This new model is considered to verify that the introduced direct schemes are general and can effectively be applied to various structures. This new ACB was modeled using ANSYS finite element analysis. Modal analysis was performed to calculate natural frequencies and the modal shapes. Harmonic and transient analyses were performed for a wide range of frequencies to demonstrate the active vibration suppression.

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This paper describes applications of fiber Bragg grating (FBG) sensors to cure monitoring of composites during autoclave molding. FBG sensors are embedded into unidirectional glass fiber reinforced plastics (GFRP) laminates for measuring internal strain. Off-axis strain measurements by FBG sensors with angles of 0,45 and 90 degrees against reinforcing direction were conducted during cure. In addition, FBG temperature sensors were developed for cure monitoring of FRP laminates. Finally, simultaneous monitoring of strain and temperature during cure was conducted by using embedded FBG strain and temperature sensors. From the results, it appeared that FBG sensors were useful for residual strain monitoring during cure. The experimental results of the simultaneous measurement showed that this system had a good performance of strain measurement under temperature-changeable conditions. Therefore, it can be concluded that embedded FBG sensors are useful for cure monitoring of FRP laminates during autoclave molding.

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Two rectangular plates, assimilable to beams, one with embedded fiber optic sensors and one with the sensor glued on its surface have been manufactured using a prepreg carbon fiber fabric. The sensors, specifically two Fiber Bragg Gratings (FBGs), have been embedded in the same in-plane position but at different depths so as to be in opposite position with respect to the neutral axis. A second plate with lower natural frequency has been tested to prove the feasibility of a modal analysis by the use of a fiber Bragg Grating. The results from the static tests have shown excellent agreement with the theory. From the dynamic tests performed with the Fiber Bragg Grating the second mode of vibration was retrieved. The comparison with the results obtained with the accelerometer was very good.

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This paper describes demonstration of simple fiber optic strain sensors proposed by Asanuma. The concept can be explained as formation of optical interference or loss type sensor in a matrix material by simply breaking a notched or multiply notched optical fiber embedded in it. The notches were made on an optical fiber with an optical fiber cutter and it was embedded in epoxy as a matrix material. When a notched optical fiber embedded epoxy matrix specimen was tensile tested under monitoring of optical transmission loss, fracture of the embedded optical fiber at the notch was clearly observed and then sinusoidal variation of optical power was observed with increasing tensile strain. This result means that an optical interference type strain sensor was successfully formed due to formation of fiber ends parallel to each other and normal to fiber axis by breakage of the optical fiber at the notch. In the case of using multiply notch type optical fiber, the distance of the notches to be able to cause multiple fractures was experimentally obtained as 4mm. Optical loss increase of the embedded optical fiber with increasing tensile strain became clearer with increasing number of optical fiber fractures from 5 to 15. The fractured fiber length could be made as small as 0.5mm by changing from tensile fracture to bending fracture.

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This paper focuses on the design, dynamic analysis, control and experimental verifications of intelligent composite structural systems with simultaneous precision positioning and vibration suppression capabilities. First, the architecture of the entire system is introduced. The configuration of the active composite panel is then determined, and its dynamics is analyzed and evaluated by the finite element method and experiments. An adaptive feedforward control scheme is proposed to perform precision positioning and vibration suppression simultaneously. The satisfactory experimental performance has been achieved, confirming that the intelligent composite structural system can reliably and efficiently produce precision position and full vibration suppression.

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PZT is piezoelectric ceramic that is the most used at ignition element, supersonic element and drive element for the micro-machine. It is very important to extend the collision fatigue life of PZT. Collision fatigue fracture of ceramic after occurred on surface defect of sample. Therefore, defect and stress relaxation of surface for extend fatigue life is effective. We confirmed binding energy of surface for before and after EB irradiation that we used ESCA. In order to extend collision fatigue life of PZT, the sheet electron beam irradiation has been performed. EB irradiation extended fatigue life and enhanced the Weibull coefficient, which indicated statistic distribution of fracture.

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Maintenance is one of the major driving cost in the management of an aircraft. To reduce such a cost a new concept is nowadays investigated by several researchers all over the world : the use of a structural health monitoring system. This paper gives a contribution in this particular field. Compact tension (CT) specimens have been cut from an aircraft vertical stabilizer, recently put out of service, made of Carbon Fiber Reinforced Plastic (CFRP). After some preliminary tests on some specimens performed to obtain the right parameters, an optical strain gauge (specifically a Fiber Bragg Grating) has been glued on the surface of one specimen and data have been collected during the fatigue test. Correlations between the behavior of the strain response, the crack propagation, the breakage of the fibers and the loads applied are presented.

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This paper describes fabrication and evaluation of an active laminate proposed by Asanuma. It was made by hot-pressing of aluminum plate as high CTE material, unidirectional CFRP prepreg as low CTE material and electric resistance heater, KFRP prepreg as low CTE material and insulator between them, and copper foils as electrodes. In this study, fabrication condition and performances such as curvature change and output force were examined. Under the optimized fabrication condition in the experimental range, it became clear that 1) curvature of the active laminate linearly changes as a function of temperature between room temperature and its hot pressing temperature by electric resistance heating of carbon fiber in the CFRP layer and cooling without hysteresis, and 2) its output force against a fixed punch during heating from 313K up to around glass transition temperature of the epoxy matrix almost linearly increases with increasing temperature.

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To examine this new concept, the present work applies the perdition method to determine the collision fatigue limit for (Pb)_<0.55> (Zr)_<0.24> (Ti)_<0.21> O_x (PZT) piezoelectric ceramics. The materials show large changes in electrical potential induced by pressure on the collision. Measurements on this type of material found a linear relationship between logarithmic electrical potential and logarithmic ideal collision energy below collision fatigue limit. On the other hand, the maximum value of electrical potential deviated substantially from the relationship at the larger collision energy (i.e., above the collision fatigue limit). Applying the large deviation from the relationship, a collision fatigue limit can be precisely determined for the PZT materials. The critical differential electrical potential (&lrtri;V_c=+/- 4V) at collision fatigue limit can be predicted. The method holds the promise of yielding the information precisely and conveniently.

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Embedding optical fibers into composite material is becoming a common procedure in various applications. Telecommunication optical fibers are commercially provided with acrylate or polyimide coating which are suitable when embedded into those materials. The situation is completely different when one think to embed optical fibers into metallic or ceramic materials or more in general when the application is at very high temperature. In this paper we use the electrowinning technique to deposit a sufficiently high thickness of a metallic protecting coating on optical fibers to be embedded into metallic and ceramic materials. A cylindrical cell has been used to electrodepose a uniform thickness of metal on optical fibers after making it conductive by a thin layer of graphite or aluminum. Metals having high melting temperature have been used to prepare the electrolyte. Different operative conditions such as current density, temperature, solution pH have been tested to optimize both process and protective coating properties.

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As shown by previous research results, the internal electrically conductive network, which is constructed by the contacts between conductive carbon fibers, is very important in correlating the measured electrical resistance change of CFRP composites under tensile loading to the mechanical damage state. In this study, the internal conductive network in CFRP is investigated experimentally and analytically. The anisotropy characteristics of the electrical conductivity in CFRP are measured for various carbon fiber volume fractions using DC 4 and 6 probe methods. The electrical ineffective length, which represents the internal conducting path due to the fiber contacts, is also estimated using the resistance change curve obtained by mechanical tensile tests. For the analytical investigation, Kirchhoff's rule for DC network circuit analysis is combined with the Monte Carlo simulation for the contact point distribution. By comparing the analytical and experimental results, the distribution configuration and the number of contact points, which constitute the internal electrically conductive network of CFRP composites, can be evaluated quantitatively.

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Active Composite Panels (ACPs) and Active Composite Struts (ACSs) are explained as basic building blocks of adaptive structures with precision positioning and vibration suppression capabilities. The use of these ACPs and ACSs in adaptive structures as building blocks with vibration suppression and precision positioning capabilities are explained. Many examples on the use of the ACP and ACS building blocks in intelligent material systems and structures are given in this paper.

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The strength prediction of the composite laminates is necessary for the engineering application. In predicting the strength of the arbitrary lay-up laminates, the interaction between the fiber failure and the ply cracks is critical. Therefore, the advanced micro-mechanical models considering the ply cracks and the fiber failures should be established. The present study investigates experimentally the microscopic damage evolution of glass fiber reinforced polymer (GFRP) cross-ply laminates and predicts the stress-strain relation up to failure using the statistical simulation. Especially, a new numerical model based on the finite element method and the Monte Carlo simulation is proposed and the fiber breakage is coupled with the matrix cracks in the 90-degree plies in this model. Concerning the matrix cracks, the present model utilizes the experimental results obtained from the replica observations. The simulated results have a good agreement with the experimental results and it is found that the present model can predict the micro mechanical damage process of GFRP.

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In order to evaluate the mechanical properties of T800H/3633 CFRP woven laminates for cryogenic tankage in RLV, tensile and in-plane shear tests were performed at room temperature, liquid nitrogen temperature (77K) and liquid helium temperature (4K). The tensile tests were conducted in accordance with ASTM D 3039 and JIS K 7073. Tensile strength and modulus were evaluated for both the warp and fill directions. A problem was encountered with obtaining acceptable failure of the specimens. We could not achieve failure in the test section. This problem was avoided by using dog-bone shaped specimens. A two-dimensional finite element analysis was also used to study the stress distributions within the specimens and to interpret the experimental measurements. The in-plane shear modulus and shear strength were measured by tensile tests on the ±45° specimens (ASTM D 3518 and JIS K 7079). The effects of temperature on the stress-strain responses in tension and in-plane shear are examined. Fracture topography of specimens is also investigated and interpreted.

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For the longitudinal tensile strength of filament wound pipes of glass fiber reinforced plastics (GFRP), Japan Industrial Standard K 7033 (JIS K 7033) was established in 1998,where three kinds of test methods (method A, B and C) were recommended for determining the tensile strengths. The objectives of this study were to compare the tensile strengths measured by each test method and to check whether each test results were acceptable or not for the modified test methods. The longitudinal tensile tests were conducted based on the JIS K 7033. For specimen geometry, a strip cut in the longitudinal direction of the pipe was used in method A, method B used a full section of the pipe and method C used a notched rectangular plate cut from a pipe wall section, so that two of the sides were parallel and the other two sides were at right angles to the longitudinal axis of the pipe. It was found that the three tensile strengths often did not agreed with each other within lower winding angles, and method C agreed with method B within higher winding angle. We discussed the accuracy of each test method, which was proposed as the simplified method to obtain the longitudinal tensile strength of the filament wound pipes.

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A new 3-D physically based constitutive model, capable of capturing the response of isotropic glassy polymers more faithfully than has been possible hitherto, was developed. It is based on an existing constitutive model proposed by Dooling, Buckley and Hinduja, but extends it to encompass the well-known deformation-induced structural evolution characteristic of glasses. The new model has been shown to correctly describe the material deformation behaviour in the nonlinear viscoelastic regime, under a variety of loading histories and different modes of deformation, including the enhanced recovery after removal of load, and stress drop after yield, with the same set of parameters. Furthermore, the model produces the right effect of varying stress invariants, a feature which has not been shown before by any other constitutive model for glassy polymers. The paper outlines the model, and illustrates how it may be applied and fitted to experimental data, by reference to the case of glassy poly (methyl methacrylate) (PMMA) in the region well below its glass transition.

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Effects of tensile loading angle on the stress-strain behavior in CFRP laminates are investigated experimentally. Both a cross-ply laminate and a woven laminate are used. The nonlinear behavior in the stress-stress curves is focused. A plasticity modeling is made to characterize the nonlinearity of the stress-strain relation.

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On the study of fracture process on AFRP debonding phenomena are very important. It is said that the fracture process on AFRP is depended on the structure of composite. The fracture sound for two sorts of AFRP, unidirectional and plain woven, was measured on tensile loading. The debonding between layers was occurred intentionally on interlaminar shear strength test and the fracture sound of debonding was measured. Both fracture sounds were compared by AE method. It was pointed that the frequency characteristic distribution of fracture sound corresponding to each debonding occurred by different mechanisms is different.

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Increased use of Carbon/Carbon composites (C/Cs) has necessitated fabrication of complex structures made of the C/Cs. To satisfy this requirement, secondary bonding technique effective at elevated temperatures should be developed. In the present study, carbon and SiC bonding between C/Cs were examined. The bonding strength and Inter-Laminar shear strength (ILSS) of C/Cs were evaluated at elevated temperatures up to 2273K in vacuum using double-notched specimens. The results revealed that both of bonding strength increased with increasing temperature. Strength of graphite has reported to be affected by absorbed water. Hence, bonding strength tests were also performed for the carbon-bonded specimens with and without evaporation treatment of absorbed water. These results indicate that the evaporation of absorbed water is a predominant factor for increasing carbon-bonding-strength with temperature. Other major factor was identified to be thermal stress during bonding process caused by mismatch of thermal expansion between substrate C/C and bonding region. This effect was quantitatively analyzed by finite element method (FEM).

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This paper describes the results of an experimental investigation of cumulative damage development in quasi-isotropic [0/+45/-45-90]_s alumina FRP laminates subjected to tension-tension fatigue loading. The onset and growth of matrix cracks and delamination were monitored with an optical microscope. The matrix crack density and the normalized length of delamination were measured as a function of the normalized number of stress cycles by edge observation. It was found that a decrease of the stiffness was observed in an early stage due to the initiation of the matrix crack, and that a different pattern of the damage evolution was observed in each lamina under tension-tension fatigue. Results of the study include a detailed description of the chronology of the damage development prior to failure. Additionally, the mechanism of the fracture of quasi-isotropic alumina FRP laminates under tension-tension fatigue was evaluated from the result such that the static strain of [0]_8 Alumina FRP laminates and fatigue failure strain of quasi-isotropic alumina FRP laminates are equivalent.

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Mullite-based porous ceramics were fabricated with two types of pore forming agents. These porous ceramics were then infiltrated with epoxy in vacuum. The porous ceramics were characterised in terms of microstructure, porosity and mechanical properties both before and after infiltration. Contact testing with a spherical indenter was used to characterise the damage response on surfaces of both porous and infiltrated samples. The machinability of the infiltrated materials was examined by grinding and scratch testing. The relationship between the microstructure, mechanical properties and machinability was examined.

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The flexural fracture behavior of four kinds of CFRP laminates with the combination of heat-resistant thermosetting resin and PAN-based carbon fiber were investigated by three-point bending tests over wide ranges of temperature and deflection rate. The flexural fracture behavior by the fractographs as well as the flexural strength strongly depend on deflection rate and temperature. The master curves for these strengths can be produced based on the time-temperature superposition principle. The time-temperature shift factor for the flexural strength of each laminates agrees well with that for the stress-strain relation of the corresponding matrix resin. Therefore, it is cleared that the time and temperature dependence of flexural fracture behavior of these CFRP laminates is mainly controlled by the viscoelastic behavior of matrix resin.

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In this study, the damage progression process for plain-woven carbon fabric composites (PW-CFCs) under cyclic loading was investigated. Under cyclic loading, the damage progression was estimated intermittently by using the thermo-elastic damage analysis (TDA) method. Crack densitiy for each layer of the specimen was also estimated at several stages of fatigue. It was found from these results that the damage progression process was divided into three stages. In the first stage, especially, the damage accumulation occurred independently in the PW-CFC specimen and progressed easily along the transverse fiber bundles. All experimental results showed that the damage progression in the first fatigue stage was explained by considering damage-units (a unit area of damage progression and accumulation). Based on the percolation theory, the damage progression for PW-CFC under cyclic loading can be characterized by regenerating the distribution pattern of damage-units.

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The dependency of creep strength for a thermoplastics Polyimide and its CFRP on time and temperature was researched. Especially, the effect of crystallization on creep phenomena was studied. And the strengthening method for creep fracture of Polyimide was discussed. For these purpose, the effects of mixing of fiber reinforcement and changing polymerization of resin on creep fracture strength were studied. Used material was a carbon fiber reinforced thermoplastics-polyimide and its fiber volume fraction was 15%. Two kinds of crystallinity were prepared, which were 0% and 31%. From the result of bending test, it was found that the strength and elastic modulus were straightly increased according to crystallization. On the other hand, fracture strain decreased due to this treatment. Using these materials, applied stress levels and test temperature dependence of the creep fracture strength were researched. The temperature conditions were from 220℃ to 280℃ which was a slightly over the glassy temperature of this resin.

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Honeycomb core sandwich panels with the GFRP laminates as skin layer and aramid honeycomb core were employed for this study. The three point bending tests for the sandwich panels as well as the GFRP laminates were carried out at wide ranges of both deflection rate and temperature. The flexural strength for laminates and panel strongly depend on time and temperature. The time-temperature superposition principle holds for the flexural strength of the sandwich panel as well as GFRP laminates. The time-temperature shift factors for both strengths agreed well with each other in the temperature range of which the compressive fracture of GFRP occurred.

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Bagasse is the waste fiber obtained after squeezing sugar cane. Our purpose is to find a more valuable usage of the bagasse as a composite material. The composite material is compounded unsaturated polyester, crushed bagasse fiber and glass fiber. FRP (Fiber Reinforced Plastic) material in our research was produced by injection molding and injection compression molding using BMC (Bulk Molding Compound) material. The product was investigated about the optimum condition in term of the mechanical strength and property. Consequently, it was found that the glass fiber was penetrated into a bagasse fiber in the injection to the cavity of the mold. The effect of fixing the glass fiber in a batgasse signified equivalently to prolong the glass fiber length. Furthermore, according to the kneading action and capillarity work in BMC, the liquefied unsaturated polyester resin was sufficiently permeated through the bagasse fiber of vegetable fiber. This phenomenon contributed to the improvement of mechanical strength because of the friction increase between resin and bagasse fiber.

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Vapor grown carbon fiber (VGCF) is a kind of carbon nanotube (CNT), which has outstanding properties such as high mechanical strength and electrical conductivity. We studied injection molding of VGCF reinforced polystyrene (PS) and evaluation of the mechanical and electrical properties comparing with the composites in which conventional carbon fillers were filled. As a result, the resistivity of the composites reinforced with VGCF drops significantly between 3 and 4 vol.% and after which it decreases linearly above 4 vol.%. The resistivity of the composites reinforced with VGCF is 1.2×(10)^2Ω・cm when the VGCF concentration is 11.6 vol.%. The resistivity is significantly lower than that of the composites which were reinforced with conventional carbon fillers. The elastic modulus slightly improves with increasing VGCF concentration, whereas the tensile strength is almost constant in the VGCF concentration range from 0 to 12 vol.%.

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The present work is dealing with the experimental investigation of the effect of moisture on the fatigue behaviour of fibre-reinforced composite materials. Flexural fatigue study of glass fibre-reinforced vinylester composite materials was undertaken in medium deflection levels. Typical fatigue tests (according to approved specifications) with dry and water-affected (30 up to 55 days in water) specimens of these materials were conducted on a three-point bending rig at a frequency of 2.4Hz. The fibre direction effect was also examined by using specimens cut in 0°, 45° and 90°. All tests were performed on a fully computerised small size fatigue testing machine especially design and built for the precise purpose.

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Effects of fiber surface oxidization and sizing treatment on both fiber strength distribution and fragmentation behavior in single carbon fiber epoxy composites are investigated experimentally. Based on the above experimental data, the fiber/matrix interfacial properties are discussed.

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Fragmentation tests have been conducted to investigate the degradation mechanism using a single fiber composite. The effects of environmental solution diffusion into the resin on the fiber strength and the interfacial shear strength have been investigated as a function of immersion time. As a result, the fiber strength did not chang in respect to an environmental solution containing water and acid. It was suggested that only water would diffuse into the resin and reach the inner fiber, and that acid would not reach the fiber. A Fickian diffusion analysis showed that the water concentration around the fiber already reached a saturation limit at the beginning of the acid diffusion. In this study, the importance of water diffusion on each material degradation was discussed. It is suggested that only water would diffuse into the resin and reach the inner fiber, and acid would not reach the fiber. Therefore, it is concluded that the water diffusion influences the degradation of materials, fiber, matrix and interface immediately before acid corrodes the fiber and interface.

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