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Volume 42 (2016)
- Issue 6 Pages 203-
- Issue 5 Pages 163-
- Issue 4 Pages 125-
- Issue 3 Pages 89-
- Issue 2 Pages 49-
- Issue 1 Pages 2-
Volume 42, Issue 5
Displaying 1-5 of 5 articles from this issue
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Research paper
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Tomohiro YOKOZEKI, Yayoi KOBAYASHI, Hiroaki ARAI, Akio OTANI, Asami NA ...2016 Volume 42 Issue 5 Pages 163-168
Published: September 15, 2016
Released on J-STAGE: September 21, 2017
JOURNAL FREE ACCESSSpace-environmentally robust light-weight materials are required for the achievement of large precise space structures. This study aims to develop polymer-based composites without dimensional change due to moisture absorption using polymethylpentene (PMP) polymer. Standard PMP and Acid-modified PMP are investigated to develop the CFRP with good mechanical properties. Moisture absorption properties of PMPs are evaluated, and it is confirmed that PMP exhibits ultralow moisture absorption. Carbon fiber (CF)/PMP composite plates are fabricated using the hot press method, and mechanical properties are evaluated. It is found that CFRP using appropriately acid-modified PMP exhibits the highest mechanical properties. Finally, water absorption properties of the developed CFRP is evaluated. It is demonstrated that CFRP using PMP is a robust light-weight space materials for moisture absorption/desorption, while unexpected water uptake by different mechanism from the standard diffusion-permeation mechanism is observed.View full abstractDownload PDF (2105K) -
Takahiro HAYASHI, Takayuki KOBAYASHI, Jun TAKAHASHI2016 Volume 42 Issue 5 Pages 169-177
Published: September 15, 2016
Released on J-STAGE: September 21, 2017
JOURNAL FREE ACCESSA rapid measurement on void content is required urgently in carbon fiber reinforced thermoplastics (CFRTP) because thermoplastic resins have high viscosity to impregnate into carbon fibers and provide tiny voids in CFRTP. In this study, the true attenuation coefficients of materials by the use of soft X-ray are necessary for quantification of the void content, which are the assumed attenuation coefficients of materials removed voids perfectly in the materials. Firstly the attenuation coefficients of graphite and PP plates and stacked of them were measured. Secondly the thickness of graphite and PP plate were transformed for that of PET plate having same transmittance respectively and treated the stacked plate as one PET plate. The transmittance of the united PET plate was calculated by transmittance-thickness approximation curve to estimate the attenuation coefficient. The estimated attenuation coefficients were almost same as the experimental data. Moreover the PET-transformation coefficients of graphite and PP plate were verified theoretically by the mass attenuation coefficients of composed atoms and their composition. Finally the estimated attenuation coefficients of CF/PP plates were almost same as the experimental values by the above mentioned method. Thus this method can be acceptable for the estimation theory of attenuation coefficient of composite materials.View full abstractDownload PDF (1323K) -
Hiroyuki OGUMA, Tomoya KUMAGAI, Daisuke SAKAMOTO, Masahiro SEKINE, Nor ...2016 Volume 42 Issue 5 Pages 178-184
Published: September 15, 2016
Released on J-STAGE: September 21, 2017
JOURNAL FREE ACCESSThe purpose of this study is to improve the mechanical properties of carbon fiber reinforced thermoplastics (CFRTP) using polycarbonate (PC) for a matrix resin. To achieve this purpose, we investigated the molding conditions of CFRTP and the surface modification method for the carbon fiber fabric (CFF) and PC sheet. Results of the examination of molding conditions, when the press pressure in the molding increased from 2 MPa to 10 MPa, flexural strength of CFRTP increased 50% compared with the original value. This reason would be due to the both things, namely increase of volume fraction (45%→57%) and decrease of void content (5.8%→3.4%) of CFRTP. In order to improve the adhesion between CFF and PC sheet, ozone oxidation treatment was adopted. This treatment was carried out for both CFF and PC sheet. In comparison with the untreated one, it was found that flexural strength and tensile strength increased 31% and 14%, respectively.View full abstractDownload PDF (2758K) -
Yoichiro KOGA, Yoshiro SUZUKI, Akira TODOROKI, Yoshihiro MIZUTANI2016 Volume 42 Issue 5 Pages 185-192
Published: 2016
Released on J-STAGE: September 21, 2017
JOURNAL FREE ACCESSCarbon fiber reinforced plastics (CFRPs) are generally used for weight reduction of industrial structures. Highly strong reinforced plastics and highly rigid matrixes in CFRP consist CFRP′s high performance (e.g. specific strength and rigidity), while CFRP can be defected inside (e.g. deferent material interface or interlaminar) by off-plate directional impact load easily to reduce their strength significantly. Therefore, periodical non-destructive testing (NDT) is required for maintenance of their integrity. In addition, CFRP has remarkable mechanical and electrical anisotropy; especially electrical resistances are approximately 1000 times different between longitudinal and orthogonal direction. In this study, we propose new thermography method for CFRP delamination detection with electrical resistance heating of intentionally selected layer by using above-mentioned CFRP′s electrical resistance anisotropy (selective-layer heating). This method can detect the delamination crack induced in an objective more deeply than the other thermography method that excite heat from an objective surface and can determine the delamination depth more precisely by excluding influence of 3-dimensional heat conduction than the other thermography method.View full abstractDownload PDF (3637K) -
Kenichi YOSHIOKA, Felix NGUYEN, Swezin THAN TUN, Go YAMAMOTO, Tomonaga ...2016 Volume 42 Issue 5 Pages 193-200
Published: September 15, 2016
Released on J-STAGE: September 21, 2017
JOURNAL FREE ACCESSIn this study, two types of carbon nanotube (CNT) with different types of CNT alignment are used as an interlaminar toughener for carbon fiber reinforced plastics (CFRP) preparation, and effects of CNT addition on the interlaminar fracture toughness of CFRP are investigated. The effects of the interlaminar toughening by addition of a thermoplastic resins are also investigated in addition to the above-mentioned CNT loading. It is well known that the impact resistance, i.e., interlaminar fracture toughness, is one of the most important properties for the development of CFRP. Even though the improvement in the interlaminar fracture toughness have been reported by adding thermoplastic resin between CFRP layers, further research is needed for the development of CFRP with lightweight and improved interlaminar fracture toughness. On the basis of these backgrounds, in this study, the effects of the CNT addition (unidirectionally aligned and randomly oriented CNTs), number of CNT layers (25 and 100 plies), location of CNT layer and thermoplastic resin addition on the mode I and mode II interlaminar fracture toughness are explored.View full abstractDownload PDF (5313K)
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