Longitudinal and flexural vibration tests of a synthetic wood (Eslon Neo Lumber FFU-50, Sekisui Chemical Co., Ltd.) were conducted with various length/depth ratios, and the Young’s modulus and shear modulus were measured. The validity of the vibration tests was examined from analyzing the effect of the specimen configuration on these moduli. The measurement method influenced on the value of Young’s modulus in the direction perpendicular to the fiber because of the fabrication process of the synthetic wood. To measure the Young’s modulus and shear modulus accurately, it was preferable to determine the length/depth ratio to be approximately 10.
Nowadays, high-durability has been required in concrete structures that assume long term-service. Therefore, generation of tobermorite in the concrete has been important for the material design of high durability concrete. The purpose of this research is to evaluate the effect of the addition of high volume CaO-MgO-SiO2-based materials with autoclave curing for the generation of tobermorite, and to clarify the generation mechanism of tobermorite from the view point of the hydration reaction of materials at heating process in autoclave curing. As a result, generation of tobermorite was increased by using high volume CaO-MgO-SiO2-based materials. It is because that C-S-H with high CaO/SiO2 ratio was maintained, since the reaction of the α-quartz at heating process in autoclave curing was suppressed by substitution of CaO-MgO-SiO2-based materials.
The present study aims to improve surface quality of tunnel lining concrete. The study developed an image analysis to detect and evaluate bugholes on concrete surface. The developed system calculates RGB value of colored images of concrete having bugholes. The study examines the accuracy and effectiveness by comparing the system to a binary image analysis. The comparative result shows that the developed system has higher accuracy than the binary image analysis. To examine generation of concrete bugholes, the developed system was employed in a vibrating consolidation test. The primary observation is that relatively small bugholes remained on concrete surface while large bugholes disappeared by vibrating consolidation.
The purpose of this study is to propose the principle for detecting the damage of TBC deposited onto the gas turbine blade based upon the electromotive force generated between TBC surface and substrate at a high temperature. The electromotive force of TBC can be easily monitored at an elevated temperature. It was found that the exposure temperature generating the electromotive force was approximately 800K, which corresponds to ductile-brittle-transition temperature of the bond coating materials CoNiCrAlY in TBC system. Thus, there is a possibility to distinguish the damage patterns of the crack as piercing to the substrate and the crack as leading to delamination of top coat by detecting the electromotive force. As a future work, it is necessary to develop a high reliable technology to connect a conductor on the actual gas turbine blade surface to detect the electromotive force and relate between the generated electromotive force and TBC delamination life.
This paper presents experimental results for the fracture properties of injection-molded glass fiber/polyamide 66 composites. A weighed amount of glass fibers was mixed with polyamide 66 using a twin extruder. The contained glass fiber was prepared from 17 to 41 vol%. Fracture tests were performed on single edge notched bend specimens. The specimens (C-0 specimens) were prepared by cutting the injection-molded plates. Injection-molded specimens fabricated by using JIS K 7162 specification mold (M specimens) were also used. The effects of the fiber orientation, fiber volume fraction and loading rate (crosshead speed) on the fracture properties were discussed. To correlate the microstructure with the fracture properties, the fracture surfaces of dyed composite specimens were examined by a scanning electron microscopy (SEM) and an optical microscopy.
The objective of this study is to investigate the dynamic viscoelastic properties of poly (ethylene terephthalate) (PET) composites with ultrasonicated nanoclay. The nanoclays were ultrasonicated in solvent, and dried in an oven. The dispersion stability of nanoclay/solvent suspensions was observed to evaluate the degree of exfoliation of nanoclays. Morphology of ultrasonicated nanoclays was also examined using a scanning electron microscope (SEM). Specimens of PET composites with ultrasonicated nanoclays were then fabricated by melt blending. Dynamic viscoelastic tests were carried out, and the effects of ultrasonication time and nanoclay volume fraction on the temperature dependence of the storage and loss moduli of the composites were discussed. Morphology of nanoclays in the composites was also examined using a transmission electron microscope (TEM). In addition to conducting experiments, finite element analyses were performed using a three-dimensional unit cell model to predict the elastic properties of nanoclay/PET composites. The effect of nanoclay morphology on the elastic properties of the composites was examined.
This study sought to align multiwalled carbon nanotubes in uncured ultraviolet ray curing resin suspension by applying traveling electric field in the whole area. The suspension coated on a 18mm × 18mm size cover glass and the coated cover glass were put on the multiple-electrode which was constructed with 24 long and slender electrodes. Rectangular and six-phase voltages were applied to the multiple-electrode. The applied voltage in one electrode had the phase differences of ±60 degrees among the voltages applied to the both side electrodes. The multiwalled carbon nanotubes in the suspension were rotated to the direction perpendicular to the electrodes. After the rotation ceased, UV rays were irradiated to the suspension for resin curing. In this way, aligned carbon nanotubes/ ultraviolet curing resin composites were produced. The electrical resistivities of the composites were measured in parallel and vertical directions to the aligned carbon nanotubes. In the latter half of this paper, the carbon nanotubes alignment was simulated under the experimental condition based on the method proposed by the author. Furthermore, the influence of the relative permittivity of the suspension on the fluctuation of the carbon nanotube orientation was theoretically clarified.
Oxidative degradation of polypropylene (PP) is accelerated by not only sunlight but also temperature. Here we propose how the degradation behavior of PP under ultraviolet light irradiation conditions at elevated temperatures, which are more severe than the standards set by the Japanese Industrial Standards (JIS), can be examined. Fourier-transform infrared spectroscopy in conjunction with gel permeation chromatography revealed that the combination of light and heat definitely accelerated the chain scission, or oxidative degradation, of PP, resulting in deterioration of mechanical properties for PP.