Journal of the Japan Society for Composite Materials
Online ISSN : 1884-8559
Print ISSN : 0385-2563
ISSN-L : 0385-2563
Current issue
Showing 1-5 articles out of 5 articles from the selected issue
Research paper
  • Shin-ichi TAKEDA, Jonathon D. TANKS, Sunao SUGIMOTO, Yutaka IWAHORI
    2019 Volume 45 Issue 6 Pages 215-222
    Published: November 15, 2019
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    A highly efficient joining method using ultrasonic welding is required for the manufacturing and processing of thermoplastic carbon fiber-reinforced plastic (CFRP) structures. Herein, the application of resin mesh as a sheet-like energy director is proposed, and its feasibility is assessed. The relationship between the welding conditions and the tensile shear strength was investigated using single lap joint specimens prepared by ultrasonic welding. The fracture surface observations indicated that resin mesh melting occurred from the end of the specimen, whereas the unmelted zone remained at the center of the welding surface. It was necessary to supply a sufficient amount of resin to the welding surface and select a resin mesh suitable for the welding conditions to minimize variations in the bonding strength. Under the welding conditions used herein, the specimens with the coarsest resin mesh showed an average tensile shear strength of 34 MPa and a coefficient of variation of 0.1. From these results, it was concluded that the application of a sheet-like energy director for the ultrasonic welding of thermoplastic CFRP is a promising method to achieve a practical level of bonding strength.

    Download PDF (4311K)
  • Takenobu SAKAI, Nur Safiah Binti SHAMSUDIM, Ryohta FUKUSHIMA, Kensuke ...
    2019 Volume 45 Issue 6 Pages 223-229
    Published: November 15, 2019
    Released: November 25, 2020
    JOURNALS FREE ACCESS
    Recently, carbon fiber reinforced thermoplastics (CFRTPs) have been widely used for various applications instead of carbon fiber reinforced thermosetting plastics (CFRPs). Some of the matrix resins of CFRTPs are crystalline polymers such as polyamide (PA), polyether ether ketone, and polyimide. In this study, the effect of the crystal state of carbon fiber reinforced polyamide 6 (PA6) on the mechanical properties of CFRTP was investigated. To understand the crystal state of PA6, differential scanning calorimetry (DSC) analysis was carried out. Increasing heat-treatment time increased the crystallinity of PA6. The results of bending tests show a relationship between bending strength and crystallinity; however, longer heat-treatment time decreased the Young’s modulus. The results of acoustic emission analysis and fractography show that 30 h of heat-treatment increased the brittleness of the matrix resin of CFRTP. To investigate the reason for this behavior, DSC analysis of CFRTP was carried out. Heat treatment for 30 h changed the crystal state compared with the other materials; therefore, bending properties were affected by the crystal state. Consequently, the crystal state must be considered to produce CFRTPs with the desired properties.
    Download PDF (2413K)
  • Wataru SHIOYA, Kiyotaka OBUNAI, Kazuya OKUBO, Takeshi ISHIKAWA
    2019 Volume 45 Issue 6 Pages 230-235
    Published: November 15, 2019
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    This study aims to propose a new joint technique to improve the static and fatigue durability of the bolted joint of a carbon fiber reinforced thermoplastic (CFRTP) plate. A pair of steel plates called “bite plates” was prepared; the plate surfaces were machined using a V-shaped cutter. Three types of polypropylene (PP) film were pressed, which included normal PP film and PP film modified by the addition of 0.5 or 1.0 wt% sub-micron glass fiber. A CFRTP plate and pair of bite plates were used to assemble the joint specimen using heat pressing with the paired PP film. Specimens of each bite plate and PP film were used for tensile shear and tensile-tensile fatigue tests. Test results demonstrated that the joint efficiency and fatigue durability were improved by using a bite plate and modified PP film. A detailed investigation of the joint under a loading condition revealed that the load transfer along the width direction of the specimen was enhanced by using a bite plate. The fractured surface observation also revealed that the interfacial shear strength between the PP and carbon fiber was improved. As such, our joint efficiency improvement mechanism was validated by the enhancement in the load transfer to the surface of the CFRTP due to the increase in its interfacial shear strength.

    Download PDF (4693K)
  • Satoshi KOBAYASHI, Shota KAZANO, Toshiko OSADA
    2019 Volume 45 Issue 6 Pages 236-241
    Published: November 15, 2019
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    The effect of molding condition on the resin impregnation behavior and associated mechanical properties were investigated for plain woven carbon fabric reinforced thermoplastic polyimide composites. Resin impregnation was accelerated with increasing molding temperature and pressure. At molding temperatures above 410ºC, resin impregnation remained unchanged with change in temperature. Tensile test results indicated that modulus and strength increased with resin impregnation. Resin impregnation was predicted using analytical models and it was found that the analysis could successfully predict the impregnation behavior, despite the difference in molding pressure and temperature.

    Download PDF (1833K)
  • Yuta NAKAGAWA, Soshi ODA, Nobuhide UDA, Yasuhisa SHINMOTO, Hiroto NAGA ...
    2019 Volume 45 Issue 6 Pages 242-250
    Published: November 15, 2019
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    Mechanical properties of semi-crystalline polymers and composites with a semi-crystalline thermoplastic matrix are highly dependent on the crystallinity and crystalline morphology. The cooling rate from the melt has the greatest effect on this along with other processing conditions. The objective of this study is to evaluate the effects of the cooling rate on the mode I and II fracture toughnesses of the composites with the semi-crystalline thermoplastic matrix. Carbon fiber/polyphenylene sulfide (CF/PPS) composites were fabricated using varying cooling rates. These rates ranged from 1 to 300ºC/min. The degree of crystallinity in the CF/PPS composites was determined using differential scanning calorimetry (DSC). Double cantilever beam (DCB) and end-notched flexure (ENF) tests were performed on the specimens to evaluate the fracture toughnesses of the CF/PPS composites with different cooling rates. Furthermore, the effect of the cooling rate on the mode I and II fracture morphologies of the CF/PPS composites is discussed.

    Download PDF (5028K)
feedback
Top