This study aims obtaining a precise strength of a glass fiber/ epoxy resin interface by taking inelastic constitutive equation which might be very important factor to be considered. A cruciform specimen method is one of the reasonable tests to investigate interfacial strength. Varying the cruciform (arm's) angles, the interfacial failure criterion under combined stress-state can be obtained. However, when the interfacial strength is beyond the matrix yield stress, inelastic stress analysis must be done in order to obtain the interfacial strength precisely. In this study, the inelastic analysis is performed and the effect on experimentally-obtained results is discussed.

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The thermoplastic Polyimide (PI) is a kind of super engineering plastic, and it is used in the advanced field with Carbon Fiber Reinforced Polyimide (CFRPI). Therefore, they are required long term reliability. On the other hands, the physical aging phenomenon must occur to PI and CFRPI under the glass transition temperature. This phenomenon makes the state of materials close to the equilibrium state, and the polymer chains will be hard to move. And it is the physical aging acts as the hardener on creep behavior, and it acts as non-linear factor on the visco-elastic theory. It is therefore, we have to reveal the effect of physical aging for the long term reliability. In this study, PI and CFRPI controlled various physical aging state were prepared. The purposes were to evaluate the progression of physical aging, and to investigate the effect of physical aging on thermal and visco-elastic properties. As a result, the progression of physical aging caused the endothermic peak at glass transition increasing on DSC analysis, the activation energy by the time-temperature superposition principle increasing and the aging shift factors calculated by the master curve for the heat treatment time increasing. Their values have the same tendency on each other, and they have the linear relationship between these values. And the value of DSC analysis can calculate the effect of physical aging easily.

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This study evaluates carbon fiber/epoxy resin interface shear strength by a single fiber pull-out test considering an effect of resin meniscus existing at a near the root of embedded fiber. Conventionally, large number of works has been done to evaluate the interfacial shear strength by the similar single fiber specimen. They assume the near root of embedded fiber is perpendicular in shape and calculate the interface shear stress at interfacial debonding occurs. In other words, they ignore the resin meniscus dominated by wettability between fiber and matrix. In fact, the near root of embedded fiber is not perpendicular in shape so that the stress concentration would be significantly mitigated by the meniscus. The assumption may mislead consequently the interface shear strength. The effect of the meniscus on the interfacial shear stress distribution is taken into account. The actual interfacial shear stress which is independent of meniscus size and fiber embedded length is obtained by comparisons of analytical results with experimental results. The characteristic of the single-fiber pull-out test and validity of the obtained shear strength are discussed.

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The fiber/matrix interface of GFRP governs the stress transfer between the fiber reinforcement and the resin matrix, moreover, affects the mechanical properties of GFRP. In fact, the interfacial adhesion of GFRP degrades in corrosive environment and leads to the interfacial debonding and the decrease of the mechanical properties. This paper deals with the degradation of interfacial adhesive strength within E-glass/epoxy interface after hydrothermal aging (i.e. immersion into hot water). Tensile tests of unidirectional GFRP laminate and cruciform shaped single fiber composite (SFC) were conducted in the fiber transverse direction to evaluate the residual strength of unidirectional GFRP and the interfacial adhesive strength after hydrothermal aging. The strength of the unidirectional GFRP decreased sharply in the early stage of hydrothermal aging and had a tendency to saturate toward certain strength. It was suggested that the residual strength of unidirectional GFRP after hydrothermal aging was dominant to the weight gain due to the water uptake regardless of the water temperatures. The interfacial adhesive strength of SFC also decreased sharply in the early stage of hydrothermal aging and continued to decrease with hydrothermal aging.

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This study aims to develop a fabrication process that improves the strength of glass fiber. The glass fiber strength was investigated by a fragmentation test. The fabrication process suggested in this paper made good use of the fracture mechanism of glass fiber. Before poring a resin to the mold, moisture around glass fiber was removed by a vacuuming treatment to improve the fiber strength. It was ascertained that the resin around the glass fiber acts as the moisture barrier. So, the strength reduction by moisture attack can be removed until the moisture in a matrix reaches to glass fiber surface. Fiber strength fabricated using the proposed process increased about 33% compared to the fiber strength fabricated by conventional process. On the other hand, interfacial strength decreased by vacuuming treatment, since the surface treatment might be removed during this process.

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Air is accelerated from the state of rest, steady laminar state, or steady transitional state in a circular pipe at a constant-acceleration until it reaches a predetermined cross-sectional mean velocity. The effects of the history of transient flow thus generated on the transition to turbulence and the axial propagation velocity of turbulence are investigated. The transitional Reynolds number of the transient flow is hardly affected by the cross-sectional mean velocity of the initial laminar flow. The axial propagation velocity of turbulence is the same magnitude as the value in a steady transitional pipe flow. An analytical solution derived for the axial velocity component of the transient laminar flow is compared favorably with the measured values.

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The use of magnetic functional fluids changes in damping force of a damper without using many complicated mechanisms. In this study, magnetic functional fluids having both micrometer- and nanometer-sized magnetic particles are used in the damper. Four magnetic functional fluids having different material and shape of micrometer-sized magnetic particles are used in the experiments. Damping forces of each damper using the magnetic functional fluids are measured under constant frequency of vibration and constant or variable applying magnetic field. It is shown that the damping force under non magnetic field, increase rate of the maximum damping force by applying magnetic field and response of the damping force under variable magnetic field.

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Technology such as spectacle lens, contact lens and laser assisted in situ keratomileusis (Lasik) operation has been developed for the people who corrected the ametropia of eyes. On the other hand, a study to evaluate the eyesight function generally by measuring the wave aberrations of eyeball optical system has begun to improve the quality of vision. In this study, the influences on lens distortion of the spectacle frame by spectacles wearing were discussed. Four kinds of lenses which are different in the lens diopter are retained to the same frame and these lens distortions are compared by experiments and finite element analysis. Analytical results suggest that the choice of the lens retaining method suitable for lens diopter (shape) is important for the correction of eyes.

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Digital holography is now being accepted as a very promising technique in the 3-D particle image velocimetry. However, the poor pixel resolution of CCD or CMOS cameras as compared to that of holographic films gives poor depth resolution for images which in turn severely undermines the usefulness of digital holography in densely populated particle fields. Two different novel techniques for the detection of the depth of small tracer particles distributed in 3-D space is presented in this paper. These techniques are based on in-line holography and the depth of the particles in both cases is measured using the numerically reconstructed images obtained from the convolution based Fresnel reconstruction formula. In the first case, the particle depth is measured by the statistical measures of light intensity within a proper rectangular sampling window around the test particle whereas in the second case, the geometric measure of the particle intensity peak is used for the determination of the particle depth. Both methods are applied to the different hologram patterns with overlapping interference fringes and the measurement results are compared and discussed in some detail.

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