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Guo Qitao,Xiao Bohan,Ohsawa Isamu,Takahashi Jun 한국탄소학회 2020 Carbon Letters Vol.30 No.3
This paper aims to experimentally and numerically explore fracture mechanism characteristics of ultra-thin chopped carbon fber tape-reinforced thermoplastics (UT-CTT) hat-shaped hollow beam under transverse static and impact loadings. Three distinct failure modes were observed in the impact bending tests, whereas only one similar progressive collapse mode was observed in the transverse bending tests. The numerical model was to incorporate some hypothetical inter-layers in UT-CTT and assign them with the failure model as cohesive zone model, which can perform non-linear characteristics with failure criterion for representing delamination failure. The dynamic material parameters for the impact model were theoretically predicted with consideration of strain-rate dependency. It shows that the proposed modeling approach for interacting damage modes can serve as a benchmark for modeling damage coupling in composite materials.
Hao Piao,Lubai Chen,Yoshiaki Kiryu,Isamu Ohsawa,Jun Takahashi 한국섬유공학회 2019 Fibers and polymers Vol.20 No.3
Carbon fiber reinforced thermoplastics (CFRTP) show relatively high mechanical properties and are expected tobe feasible materials for mass production of light-weight structures. In particular, discontinuous CFRTP (DCFRTP) with affordable resins have been developed to realize excellent formability and mechanical properties. Currently, polyamide 6 (PA6) is a promising matrix for CFRTP in mass-produced automobiles. However, due to the hygroscopic and viscoelastic properties of polyamide resins, the influence of water absorption on the mechanical properties of CFRTP under varying temperature is necessary to be investigated. In this study, the influence of water absorption on the mechanical properties of discontinuous CF/PA6 composites was investigated. Chopped carbon fiber tape reinforced thermoplastics (CTT), which are randomly oriented strand (ROS) composites, were selected as DCFRTP. The mechanical properties of the composites were investigated by a three point bending test between -40 and 125 oC, as a function of water absorption. The flexural modulus were calculated using the Timoshenko beam equation to predict degradation by water absorption. The mechanical properties of CTT have a relatively high sensitivity to water absorption.