The two vibration analysis methods which are Modal Analysis used in the low frequency and Statistical Energy Analysis (SEA) used in the high frequency are used as to the target frequency. The method to evaluate which vibration analysis procedure is used is discussed. Previous method needs mode density which is introduced by simulation, but this method can determine by only experiment without simulation. First showing the relationship between Motion Equation used in Modal Analysis and Energy of SEA. And in analysis model, the relationship is validated. Next, proposing the method using the ratio of real part of power and imaginary part of that and defining the middle frequency range. At last, the method is applied to the experiment.

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A bifilar suspension pendulum, a uniform density bar suspended at its two points by two strings of same length, may swing in a vertical plane or make torsional oscillation about a vertical axis. The swinging in a co-plane of the strings and the bar is called Mode 1, and the swinging in a vertical plane perpendicular to the bar is Mode 2 Mode 3 is the torsional oscillation about a vertical axis. These modes are linearly independent of each other, but it is possible to make nonlinear coupling oscillation between the modes and internal resonance. In order to treat such coupling systematically, the formulation of the problems is made on two spherical coordinates systems and equations of motion for the three modes are derived. Linear oscillations are examined for the three modes based on experiments to solve nonlinear coupling.

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Given the frequency of seismic waves close to the resonant frequency of the structure, the structure causes large vibration. The resonant frequency of the structure is determined by the value of stiffness (spring constant). As a method to shift the resonance frequency, dynamic absorber using the additional mass is well known, however, the performance is restrictive. A proposed Semi-active control by the variable stiffness of the additional mass performs varying the stiffness based on the frequency to shift the resonant frequency of the structure from the earthquake. Damping effect of the semi-active control was verified by simulations and experiments using some seismic waves.

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Particle dampers are passive vibration control devices that consist of two or more particles operating in the container of a primary system. Because their construction is simple, and their maintenance performance is high and there is little change of the damping effect by temperature, they have been the subject of several studies. Although most of the papers present the damping effect in a single-degree-of-freedom system, their performances in a multi-degrees-of-freedom system have not yet been completed In this paper, the dynamics of a particle damper in a two-degrees-of-freedom system was investigated both experimentally and analytically. The analytical method based on the discrete element method (DEM) was suggested, and the validity of the analysis was verified as comparing with the experimental result. Moreover, it is found that damping effect depends on the mass ratio and the container length.

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In this paper, a damping model of particle damping is investigated. The impact force of between granular materials and the damper container was calculated by means of the discrete element method. The impact force was divided into the real part and the imaginary one by the Fast Fourier Transform. Their real part and imaginary one were then approximated appropriate curves. The damping effect of the particle damper was computed from the approximated curve. The validity of the damping model was confirmed by a comparison of experimental and analytical results. The influence of partied number on the damping performance is investigated.

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A passive mass damper is not effective except specific frequency. Therefore, it is generally necessary to use several dynamic absorbers to suppress two or more vibration modes. In this paper, it aims at suppression in the primary and secondary modes with one semi-active dynamic absorber which consists of the air dampers and spring installed on the top of the two degrees of freedom structure. The air dampers can change the damping and stiffness by the slit of the valve. The semi-active control which switches the slit by an electromagnetic valve according to the frequency of the structure improves the suppression of two vibration modes.

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The performance of a mass measurement system with a damped dynamic vibration absorber was studied xperimentally. The measurement system utilizes the fixed point of a mass-spring system with a dynamic vibration absorber so that mass is estimated independently of damping in the absorber. It is characterized by using the phase-looked loop to achieve the tuning condition. The principle of measurement was described based on a mathematical model. A measuring apparatus was designed and fabricated. Several basic characteristics were studied experimentally. The average error of measurement was within 0.2%.

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This paper describes the simulation of vibration isolator with active mass damper that also works as vibration sensor. The active mass damper works as vibration sensor in low frequency range, and works as ordinary active mass damper m mid and high frequency ranges. Vibration control m low frequency range is done by low response actuator. Vibration sensing m mid and high frequency ranges is done by low cost vibration sensor. Thus, reduction of cost of vibration isolator is aimed. In this paper, simulation of a single-degree-of-freedom system is described. It is shown that the proposed concept has the possibility of realization.

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To achieve higher thermal efficiency of HEVs, the model based development becomes more important because its system is more complex rather than conventional ICE vehicles. To solve this problem, HEV model that includes models of a diesel ICE, a motor and a battery are constructed. The model keeps the energy balance on the power train by using energy transduction efficiency of the electronic components. By using the model, it is enable to obtain the performance of components as well as that of power train under NEDC test cycle. As a result, the parameter which limits the performance of the power train is estimated.

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The purpose of this study is to examine the effectiveness of active seat suspension when it is applied to small cars and the problems associated with its practical use. A small active seat suspension is installed for one-seater electric automobiles. In an actual driving test, a test road, in which the concavity and convexity of an actual road surface were simulated using hard rubber and gravel road, has been prepared and the vibration suppression performance and robustness of vertical vibrations of the seat surface during driving has been examined. In this paper, we examined the effectiveness of the active seat suspension in outdoor. As a result, the comfortability in riding improvement of the small vehicle was able to confirm that active seat suspension was effective on off road.

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Unlike conventional automobiles, small vehicles may frequently travel on poor roads, such as narrow and unpaved roads, thus degrading, the ride comfort. To solve this problem, researchers in our laboratory have proposed an active seat suspension that can be installed in small electric automobiles. Most studies have not focused on the psychological and physiological effects of active seat suspension on the ride comfort of small vehicles. In this study, focusing on the moods of drivers as psychological factors affecting ride comfort, we examined physiological information in terms of biological reactions, as well as psychological information. In an experiment, the heart rate fluctuations were measured as biological reactions to monitor autonomic nerve activity.

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The attitude of wheeled inverted pendulum robot can be stabilized in the neighborhood of equilibrium by applying a linear controller. Furthermore, from the previous study, the robot can track a given desired trajectory by applying the control method that modifies the rotational input according to the translational speed. The purpose of this study is to move some robots in a row along the desired trajectory. The follower robot is controlled in order to track the desired trajectory, keeping a distance to the leader robot. Some candidates of the translational inputs of the follower robot are proposed. The candidates are compared and evaluated in the simulations.

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The purpose of this study is to move a vehicle type robot from an initial position to a given desired position and attitude. First, the candidates for target trajectory are constructed with arcs and tangent line, taking account of minimum turning radius of the robot. Second, the robot is controlled for tracking the shortest trajectory in the candidates. The controller was designed based on the time-state control form. From experimental results, it was confirmed that a vehicle type robot reached the desired position with desired direction.

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This paper proposes new type of compressor that can deliver the air alternative directions. This compressor is made by replacing the location of inhalation/exhalation air port into proper position of ordinary vane type air compressor. This compressor can select the direction/speed of cylinder by changing the clockwise/counterclockwise rotational direction and the rotational speed of compressor and does not need an/the extensional solenoid valve/s. In this report, we choose components of this compressor. The air motor that composes this compressor is paid to attention, and a new sample is examined. Furthermore, we compare electrical power consumption that this system and standard system having the solenoid valve/s.

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Potential flow in centrifugal pump is analyzed by vortex methods. Complex potential is defined by a point source and multiple vortices representing pump impellers. Displacement flow is also included and inlet swirl is modeled by a single circulation at the origin. Flow tangency condition is applied at the mid points between vortices. Both radial and logarithmic spiral impellers are analyzed It is found that the present numerical results well agree with those of Acosta's conformal mapping method. We also present the stream function and the pressure distribution of impellers. Head coefficient is almost the same between vortex methods and conformal methods.

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In this study, the aerodynamic performance of the ultra-highly loaded turbine cascade (UHLTC) with the turning angle of 160 degree was measured by using the small annular turbine cascade test rig and assessed by comparing with that of the conventional turbine cascade (CTC) which has the turning angle of 113.3 degree. The measurements for the torque and the total pressures at the inlet and the outlet of turbine stage were performed for several initial rotational speeds in order to evaluate the power output and the turbine efficiency. The measured results showed that the aerodynamic performance of UHLTC was superior to that of the CTC at low flow coefficient region. However, the maximum efficiency exhibited the higher value for the CTC.

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The pressure loss characteristics of the flow between the upstream and the downstream of the rotating perforated cylinder in the pipe were investigated experimentally. The effects of the flow rate, the number of holes and the rotational speed on the loss characteristics were examined. The Reynolds number was calculated based on the flow rate. The results show that the pressure loss coefficients decrease with an increase of the Reynolds number and the number of holes except the 8-hole case. The results for the 8-hole case indicate that, the rotational energy input given to the flow through holes on the rotational cylinder increases as the rotational speed increases, and consequently the loss decreases.

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In the vaneless diffuser of centrifugal compressor or blower, the rotating stall occurs at the lower flow rate due the backflow from the diffuser. In this paper, the effect of swirl flow on the rotating stall was investigated by the three-dimensional numerical simulation. In order to investigate the effect of swirl flow on the rotating stall, the flow of rotating cylinder between the stationary disks without the rotating blades and inflow was calculated. The region of high circumferential velocity rotates with the frequency of 1.6Hz slightly higher than the frequency of 1.4Hz obtained from the experiments. The vortex found in the meridional plane between the stationary disks appears with the flow to the rotating cylinder from, and disappear with the flow to the outside.

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A fluid transport device utilizing a diffuser is investigated based on an experiment. The fluid in a diffuser was excited by the reciprocating motion of a piston integrated in the side wall. The flow fields was visualized by a laser sheet and a high-speed camera. The velocity fields are calculated by the particle image velocimetry based on the captured movies. Since the waveform of the sum of the inlet and the outlet flow rate agrees well with that of flow rate calculated based on the temporal displacement of the piston, the present PIV results can be said to be valid. Moreover, the amplitude of flow rate fluctuation at the outlet was larger about 3.5 times than that at the inlet. It implies the present device can transport fluid from an inlet to an outlet.

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Characteristics of velocity-fields and pressure-fields of a swirling flow in a disk shape planar solid oxide fuel cell (SOFC) were experimentally investigated with the aid of a particle image velocimetry (PIV). In the case of applying circle involute shape current collectors, a swirling flow was generated and its velocity in a core region was kept at nearly constant value toward the channel exit. Furthermore, pressure gradient normal to the current collector surface was observed at higher flow rate. In order to understand the above mentioned flow behavior, a swirling fluid motion was examined by using steady state Euler's equation of motion, and then we confirmed that a centripetal acceleration term contributes a production of the pressure gradient.

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The endothelial nitric oxide synthase (eNOS) in vascular endothelial cells plays an important role m the vasodilatation under hypoxia. The vasodilatation is nitric oxide requires the activity of eNOS (phosphorylation of serine residues) generated by. This study, which examined the effect of Serine 633 (m human sequence) phosphorylation of eNOS by fluid shear stress is hypoxic environment. The hypoxic cultured endothelial cells, phosphorylation was not increased in the 15min after loading. In contrast, when the load of fluid shear stress and hypoxia, there was an increase in load after 15 mm, when the load was the same fluid shear stress. The eNOS in vascular endothelial cells are suggested to be affected by fluid shear stress than hypoxia.

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The incidence of hypertension is increased in low-temperature environment Cold induced hypertension cause a decrease of Nitrci Oxide (NO) production in the blood vessel. In the blood vessel, NO is producted by Endothelial Nitric Oxide Synthase (eNOS) Subcellular localization pattern of eNOS is changed when NO production of eNOS stimulated by shear stress. However, it is not known eNOS translocation in low-temperature environment. In this study, we observed subcellular localization of eNOS under shear stress at 37℃ and 4℃ 37℃ shear stress promoted eNOS translocation In contrast, 4℃ shear stress did not change eNOS localization. These results will help to reveal the mechanism of cold induced hypertension.

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The flow between coaxial double circular disks in an open space was investigated based on an experiment. The one disk was rotated and the other was set stationary. The diameter of the disks and the spacing between the two disks were 200 and 30 mm, respectively. The rotation speeds of 6000, 8000 and 10000 rpm were examined. The radial and azimuthal components of the flow velocity were measured by an X-type hot-wire anemometer on the periphery of the space between double circular disks. The fluid in the vicinity of the rotating disk was transported in the outer direction. On the other hand, the one in the middle region of two disks flowed in the inner direction. In addition, the fluid near the stationary disk was almost stationary.

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In the present study, the viscous micropump using a rotating circular disk in an elbow duct is investigated based on the centimeter-scale model experiments. The low Reynolds number was realized by using glycerin as a working fluid. The flow is visualized by a lazer sheet and a high-speed camera. The velocity fields are calculated based on the captured movies using the particle image velocimetry. The head difference between the upstream and downstream tanks of 12 mm was obtained, which indicates the present viscous pump model using a rotating circular disk in an elbow duct can work as a micropump. The PIV results show that even fluid is still rotating even relatively far from rotating disk.

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It is known that the aerodynamic characteristics such as the sphere in critical region depend on the surface structure. The purpose of this study is to clarify the effect of the surface structural change to aerodynamic characteristics of sphere in laminar boundary layer. The experiment is carried out by numerical analysis and visualization around sphere. This visualization images taken by high speed camera at a 500fps with green laser sheet at 50mW and 200mW used a water mist or ORGASOL. As a result of these experiments and numerical analysis, the flow field of sphere is different in laminar boundary layer by the effect of the surface structural change.

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The objective of this study is to understand the effects of the depths, widths and intervals of grooves on square cylinders for the flow characteristics. Experimental investigations on the flow around square cylinders were carried out at Re=7.4x10^4. Flow visualization with the Spark tracing method was also implemented. As the result we can determine the effect of flow characteristic by groove's interval and width in many condition. It is found that the drag coefficients of the square cylinder with grooves reduce in comparison with the square cylinder without grooves. Moreover, increasing the groove interval is more effective for reducing the drag coefficient than increasing the groove width.

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As part of the investigation of the dynamic instability of Tainter-gate, the field vibration tests on full-scale operational Tainter-gates were conducted As a result, the possible existence of a coupled-mode self-excited vibration mechanism, which involves the dangerous dynamic coupling of the whole gate rigid-body rotational vibration with a "parallel" bending of the skinplate, was suggested. This paper presents that the 2-dimensional model test, which was undertaken to confirm the existence of the coupled-mode self-excited vibration with skinplate parallel bending mode.

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Experiments are conducted with the windmill of perpendicular axis type using variable flap wings. It means flap angles are changed in the experiments, although usually flap angle of windmill is fixed at a specific value. The wing attack angles are also changed in the experiments. The amount of power generation as well as the efficiency of power generation are measured by changing the flap angles of 0〜20°and wing attack angles of 0〜60°. The finding are as follows. To increase the power generation, (1)the wing attack angle should be large, (2)the flap angle is not necessary, and also (3)the use of three wing type windmill is better tham that of four wing type.

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The present study investigate the effect of flap angle of airfoil and wing attack angle to obtain the amount of power generation. We also examine the minimum starting wind velocity of the windmill. Flap wing generate electricity efficiently by using the high wing attack angle. And using high flap angle make it possible to obtain minimum starting velocity. To obtain high output power, it is better to keep flap angle of 0° and using high wing attack angle we have obtain maximum output power with wing attack angle of a =29.9° 〜-37.1° .

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It is well known that the flow patterns of high-speed air flow resemble with those of shallow water flow. Riemann problem handles a shock" tube flow and the analytical solutions are obtained Flow phenomenon with a normal shock wave is almost instantaneous and expensive equipments are necessary to detect the transient flow On the other hand, a dam-break flow appears in hydraulics. We recognize that the dam-break flow is regarded as a hydraulic shock tube where unsteady flow can be photographed very easily. This paper discusses about the relationship and characteristic of shock tube and dam-break flows and hydraulic shock-tube experiment is conducted. It is found that the progressive hydraulic jump is well predicted by Riemann solution together with reflected hydraulic jump.

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It is well known that some sources of noise, which radiates from an exhaust pipe of a reciprocating engine, exist in the flow field of the pipe end. The Compression wave generated at the exhaust port goes downstream, and changing to a shock wave as it propagates in the exhaust pipe A vortex is generated near an edge of pipe end as the shock wave is discharged from it. Under a certain condition, the shock wave is formed m the vortex ring. The shock m vortex is considered to be a cause of noise. In this research, in order to clarify the relation between vortex behavior and formation of the shock in vortex, the convective velocity of 2D vortex is measured using a laser system. And a flow field near the pipe end is visualized by the shadowgraph method.

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The underexpanded jet is broadly used in industries such as a cooling jet of heat-tempered glass and an assist gas of laser cutting In this study, a cooling effect was examined of the underexpanded jet impinging on a flat plate. The temperature distribution is visualized using a liquid crystal sheet, and additionally the static and total pressures are measured on the plate. As a result, two cooling rings appear on the plate and these locations are fixed regardless of nozzle-plate spacing.Furthermore, the raynolds number distribution was found to be independent of the nozzle-plate spacing Finally, the relation between the temperature and pressure distributions is discussed.

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Characteristics of a plasma actuator driven by direct-current discharge were studied experimentally in a Mach 3 supersonic flow. The discharge is generated between two small pin electrodes mounted on a Laval nozzle wall Current and voltage measurements indicated the generation of the discharge at low power consumption. It was confirmed that the wall static pressure increased beside an anode and decreased just behind the anode for a 100mA discharge. Furthermore, the increases in stagnation pressure and flow velocity were observed close to the electrode surface. It was suggested that enthalpy elevation due to the Joule heating of the flow led to the change in the stagnation pressure and increase in the flow velocity.

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The automotive industries expect to replace conventional steel with CFRP to decrease fuel consumption. Since it is essential to recycle the composite parts for mass production in the automotive industries, CFRP/adhesive interface requires not only sufficient strength but property of disassemble by loading as necessary direction. In the present study, we propose m-mold surface preparation, and control the adhesion of the interface. In the m-mold surface preparation, the mold with the micro structures is transferred to the CFRP surface by pressure forming process. As a result of DCB tests, it was confirmed that as aspect ratio increased, apparent fracture toughness becomes higher. It was also found that the proposed surface has anisotropic fracture toughness in the different crack propagating.

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Vacuum assisted resin transfer molding (VaRTM) is a manufacturing method of fiber reinforced polymer composites, and has the advantage of a low-cost because of unnecessary of autoclave. In anisotropic fabric, direction of resin flow may affect to void formation since the fiber structure differs from the direction against the fiber orientations. In this work, the mechanism of void formation in a plane woven anisotropic fabric is investigated. We constructed analytical model of void formation between fiber bundles m plane woven fabric, it was shown that anisotropy of fiber affects the relationship between impregnation velocity and void content.

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The mechanical strength of FRP material depends on the fibers or other reinforced materials. In case of using continuous fibers for reinforcement, however, if fibers are loose or bent, fiber's property may not be reflected FRP mechanical property enough. In this study, it reports the effect of fiber condition by experiment and analyzing FRP materials whose fibers are applied initial strain formed by a hot press machine. As a result, the initial fiber strain increases the elastic modulus.

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This paper presents a method for monitoring impact damages m FRP pressure vessels based on impact force identification. When an impact event occurs, the location and force history of the impact force are identified using experimental transfer matrices which relate the impact force and the measured strain responses. Then, the location of the damage is predicted from the impact location, and the extent of the damage is estimated using an experimental relation between the impact damage and the peak force. In the present study, the experimental relation was preliminarily determined by conducting drop-weight impact tests. The validity of the present method is verified experimentally by estimating the impact damage in a FRP pressure vessel which was induced by a drop-weight impact test. The results reveal that the location and extent of the impact damage can be estimated with sufficient accuracy using the present method.

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Carbon-fiber reinforced epoxy was decomposed using supercritical methanol to reclaim carbon fibers. The tensile and interfacial strength of the reclaimed carbon fibers was measured. The tensile strength decreased by 2-10% after decomposition treatment. The interfacial strength decreased by 23-25% after decomposition treatment XPS analysis revealed that functional groups on carbon fibers reduced due to treatment. In addition, the interlaminar shear strength of composite plates was measured. The interlaminar shear strength was not affected by the decrease of interfacial strength.

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Bioactive ceramics/poly-L-lactic acid (PLLA) composites have been expected as a material for the bone fracture fixations which have more biocompatibility than monolithic PLLA. In this study, monolithic PLLA and β-tricalcium phosphate (P-TCP)/PLLA composites containing three differentβ-TCP contents (5, 10, 15 wt%) were prepared by injection molding and tested to clarify the effect of hydrolysis and strain rates on the mechanical properties. These composites were immersed in phosphate buffered solution, and then molecular weight measurement and compressive tests at the strain rates ranging from 10"3 to 10"1 /s were performed. Molecular weight of 15 wt% composites were decreased from 154 000 to 91 000. In the results of compressive tests, P-TCP/PLLA composites showed that their Young's modulus have no dependence on the strain rate and their compressive strength increased with increasing strain rates After 24 weeks immersion, compressive strength of composites was decreased.

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Natural fiber reinforced composite materials attracts attentions because of a present global environment problem. Continuous natural fiber reinforced thermoplastic composites have superior mechanical property and have often been expected as structural materials. However, it is difficult to impregnate reinforcing fiber yarns with thermoplastics because of high viscosity of molten plastics. In this study, continuous fiber reinforced thermoplastic composites were obtained using intermediate materials fabricated through the Micro-Braiding technique. In this study, hemp and poly (lactic acid) (PLA) fibers were used as reinforcement and matrix, respectively. Composite plates were fabricated by hot press molding under various molding conditions, including molding temperature, pressure and time Evaluations of mechanical properties were conducted. The correlation between interfacial strength and shear strength of hemp fiber/PLA composite was obtained. It is good correlation between interfacial strength and shear strength.

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In order to improve interfacial properties of an adherend of the bonded composites joints, in-mold surface preparation using imprint lithography is proposed. In the proposed method, microstructures are fabricated on the surface of the mold for forming composite materials. By forming composites on the mold, the shape of microstructures is transferred to the CFRP surface. In this method, since molding of composites and surface preparation can be conducted at once, it reduces the time required and costs involved in conventional surface preparation such as sand blasting, chemical etching etc In this paper, micro concavo-convex structures are fabricated on the surface of CFRP by in-mold surface preparation to improve the apparent mode I fracture toughness of CFRP/adhesive interface According to DCB tests, it was confirmed that the fracture toughness became stronger and fracture mode changed from interfacial failure to cohesive failure of adhesive as the aspect ratio A of microstructures increased.

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Nanofibers are received much attention due to their superior properties and their application are carried out in various field. In this study, the nanofibers were produced by using a electrospmning method and the waste triacetyl cellulose (TAC) with a electrospmning method. The produced nanofibers were applied interface of fibers and matrix of FRP The FRP was composed of glass fibers and unsaturated polyester resins and the nanofibers were coated to the surface of glass fibers. For confirming the effects of the nanofibers, another FRP was fabricated without the nanofibers. The results of tensile test showed that the strength of specimens with the nanofibers was larger than that of the none nanofibers specimens. The results of m-situ SEM observation showed that the number of crack and the length of interface delammation of specimens with the nanofibers were less than those of none nanofibers specimens.

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In recent years, CFRP is expected to be main material for fabricating large scale wind turbine blades. However, there is some fear of damage in the thickness direction of CFRP laminates caused by impact loads because there are no fibers. When CFRP laminates have interior damages, their vibrational properties change and they can be estimated by a non-destructive method. In this paper, the natural frequencies and damping ratio of the CFRP wind turbine blades were measured by using an impulse hammer test. Next, their mode shapes were investigated from the experimental results by using a mode analysis software. Furthermore, these results were compared with numerical ones obtained by FEM.

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Tensile tests are performed using notched CFRP laminates with different layer thickness, interlaminar property and molding method to evaluate the notched strength and damage behavior. Compared with standard ply thickness laminates, thin ply laminates have a large reduction in normalized notched strength. Thus, thin ply laminates are significantly affected by the stress concentration. Laminates which have high interlaminar fracture toughness are nearly independent of the notch size Compared with laminates made by autoclave molding, the notched strength of laminates made by VaRTM method has a large variation between individuals. For the VaRTM composites, stress distribution near the notch edge is changed due to the positional relationship between notch edge and resin pocket which is caused by stiches used in non-crimp fabric. Consequently, notched strength of VaRTM composites are affected significantly by the resin pocket.

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We estimate effects of ply thickness in mechanical properties and damage evolution of CFRP angle-ply laminates under various tensile loading. It should be noted that the laminate thickness is almost the same, but the ply thickness are quite different. Monotonic tensile tests , cyclic loading-unloading tensile tests and stress relaxation tensile tests are performed on [(±)_12]_s(t-O.O5prepregx48plies), [(±)_4]_s(t-O.15prepregxl6plies) and [(+θ_4/(-θ)_4]_s (t-0.15prepregxl6plies) T700SC/2500 carbon/epoxy laminates with various fiber directions (θ=30, 40, 45, 50 and 67.5°) .Ply thickness is expressed as t-0 05, t-0 15 and t-0 6, respectively. Damage evolution can be determined by cyclic loading-unloading tests. We use mesoscale damage model to investigate damage evolution in CFRP laminates. We discuss effect of ply thickness on mechanical property of angle-ply laminates. Laminates have thin ply thickness showed high strength and fracture strain.

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There are attempts to enhance adhesion strength by fabricating micro structure on composite surface using imprint lithography. Because of the nature of the technology, surface fabrication is limited to 2.5-D surface. In the present paper, we propose a process of transcription of three dimensional shape including mechanical interlock elements using soluble mold by imprint lithography. We fabricated the soluble mold using negative photoresist by inclined exposure, and we conducted imprint process for CFRP using the mold. As a result, the three dimensional surfaces are successfully imprinted on the CFRP surface.

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For manufacturing of FRP by vacuum assisted resin transfer molding (VaRTM), unexpected resin flow occurs due to slight difference of vacuum bag wrinkle or misalignment of fabrics Since these unexpected resin flow induce dry spots, the methods to control resin flow are highly demanded. In the present study, we propose a method to determine the optimum port open/close sequence from the void fraction estimated by numerical calculation. By the proposed method, the resin flows at an optimum rate, and it enables to create high-quality FRP with low void content.

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Phenolic resin has originally advantages of heat proof, fire resistance and less smoke during burning. The CFRP with phenolic resin having these advantages is one of suitable materials in structures of vessels and railway carriages. However, a resole type of phenolic resin generates water formed from the condensation reaction. As a result, the strength of phenolic CFRP varies widely owing to the voids. The authors developed a method of injection molding for fabrication a new type of phenolic CFRP. This CFRP was composed of novolak type of phenolic resin as a matrix and carbon fabrics as a reinforcement. In order to evaluate mechanical properties of phenolic CFRP under high temperature, we carried out tensile test under high temperatures. As a result, the phenolic CFRP showed high mechanical properties under high temperature.

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In the present study, fiber/matrix interfacial property is characterized under combined (tensile and shear) stress using thick glass rod/epoxy model composites. It is attempted to detect the debonding initiation location and to observe the debonding growth behavior in a specimen with a thick glass fiber. The initiation and propagation of interfacial debonding are experimentally clarified by tensile test with straight and cruciform specimen. Moreover, fiber/matrix interfacial property is characterized by stress analysis using finite element method (FEM). The effect of neighboring fiber could be investigated to consider thermal shrinkage as chemical shrinkage. From this result, the accurate interfacial strength is estimated by the analysis which takes into account thermal shrinkage.

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Application of CFRP to cryogenic propellant tanks is expected to reduce the structural weight of space transportation system significantly. However, the delamination between CFRP and A1 alloy happened at cryogenic temperature. Therefore, it is important to investigate the fracture behavior of adhesively bonded joint of CFRP laminates and Aluminum liner for designing CFRP cryogenic tanks. In this study, FEM models for crack propagation in CFRP adhesive bonded joint under cryogenic temperature (-196℃) were proposed. To obtain the material properties for FEM models, the authors performed tensile tests and CT tests with Epoxy adhesive at cryogenic temperature. To verify FEM models, FEA results were compared with the results of DCB tests.

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