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Volume 34 (2008)
- Issue 6 Pages 211-
- Issue 5 Pages 173-
- Issue 4 Pages 133-
- Issue 3 Pages 95-
- Issue 2 Pages 51-
- Issue 1 Pages 3-
Volume 34, Issue 3
Displaying 1-3 of 3 articles from this issue
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Research paper
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Yoshihiko ARAO, Jun KOYANAGI, Hiroshi HATTA, Hiroyuki KAWADA2008 Volume 34 Issue 3 Pages 95-101
Published: 2008
Released on J-STAGE: June 10, 2010
JOURNAL FREE ACCESSMoisture absorption behavior of CFRP and its effect on dimensional stability was examined. Moisture diffusivity in CFRP was determined by measuring specimen weight during the moisture absorption test. Three types of CFRP specimens, unidirectionally reinforced, quasi-isotropically laminated and cloth-laminated composites were prepared. Each CFRP was processed into two geometries; a thin plate for determination of diffusion constants and a rod with square cross-section for the discussion of two-dimensional diffusion behavior. Coefficient of moisture expansion (CME) was also obtained from specimen deformation involving moisture absorption. During moisture absorption, the specimen surfaces strongly deformed especially near the edges because of three-dimensional moisture concentration distribution. This deformation was reasonably predicted by the finite element analysis using diffusion constants and CME, which have been experimentally determined. For unidirectional CFRP, an effect of fiber location distribution on CME is discussed by a micromechanical FEA.View full abstractDownload PDF (883K) -
Takayuki KUSAKA, Keiko WATANABE, Masaki HOJO, Toshiyasu FUKUOKA, Masay ...2008 Volume 34 Issue 3 Pages 102-108
Published: 2008
Released on J-STAGE: June 10, 2010
JOURNAL FREE ACCESSThe mode I interlaminar fracture behavior of the composite laminates reinforced with Zanchor process which is a novel through-the-thickness reinforcement technique developed by Mitsubishi Heavy Industries and Shikibo, was studied on the basis of the experimental results using DCB (Double Cantilever Beam) specimens. The effects of the Zanchor reinforcement on the macroscopic fracture toughness and microscopic fracture morphology were mainly focused on. Experimental results demonstrated that the mode I interlaminar fracture toughness was remarkably improved by the Zanchor reinforcement, where the fracture toughness, GIC, increased almost linearly with the Zanchor density, Z. In addition, the fracture toughness, GIC, increased drastically during the early stage of crack growth in the Zanchor reinforced composites, where the interlaminar crack propagated stably accompanied by a large amount of fiber bridgings. The above results suggested that the increase in mode I fracture toughness was the consequence of the fiber bridgings induced by the Zanchor process. The fracture toughness, GIC, could be precisely calculated by using the chord compliance, Cchord, though obvious nonlinearity was observed in the load-displacement responses of DCB specimens.View full abstractDownload PDF (1915K) -
Yutaka ONO, Takahira AOKI, Toshio OGASAWARA2008 Volume 34 Issue 3 Pages 109-117
Published: 2008
Released on J-STAGE: June 10, 2010
JOURNAL FREE ACCESSThough excellent performances in various properties of carbon nanotubes (CNT) are widely recognized, existing reports on the mechanical properties of their composites are not as favorable as being expected. Focusing on the tensile stiffness of CNT composites, factors that may possibly be linked with the performance degradations are evaluated. These factors include CNT distribution orientation, its aspect ratio and waviness, and CNT/resin interface properties. The micromechanics inclusion model based on Eshelby tensor, combined with Mori-Tanaka theorem is adopted in this study. The spatial orientation distribution does affect the composite stiffness, tendency of which is predictable. The aspect ratio of the CNT has relatively small effect on the stiffness, whereas the impact of waviness change is drastic, which may result in as high as 40% reduction with the waviness ratio of 0.1. The effect of interface property may depend on the way it is modeled, but the numerical results suggest that the interface bonding characteristics is one of the major issues to be focused on.View full abstractDownload PDF (625K)
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