Mode II Interlaminar Fracture Toughness of CNF-CFRP Hybrid Composite

2006 ◽  
Author(s):  
Masahiro Arai ◽  
Koh-Ichi Sugimoto ◽  
Morinobu Endo
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Hybrid Composites ◽  
Beam Theory ◽  
Mode Ii ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture ◽  
Cfrp Laminates ◽  
Nano Fiber ◽  
Hybrid Laminates

Interlaminar fracture toughness for mode II deformation were investigated for carbon fiber (CF)/epoxy laminates toughened by carbon-nano-fiber/epoxy interlayer. Vapor grown carbon fiber (VGCF) and vapor grown carbon ‘nano’ fiber (VGNF) were chosen as the stiffeners for the interlayer. In order to illustrate the effect of the interlayer on the model II fracture toughness of the laminates, several types of CFRP/CNF hybrid laminates were fabricated, which are composed of unidirectional prepregs and carbon nano fiber varying the thickness of the interlayer. Mode II interlaminar fracture toughnesses of the hybrid composites were evaluated by end notched flexure (ENF) test using short-type beam specimens. The fracture toughnesses were calculated by traditional beam theory using the energy release rate of the crack. From the experimental results, it is confirmed that the mode II interlaminar fracture toughnesses for hybrid laminates are from 2.0 to 3.0 times higher than that of original CFRP laminates, and the optimal thickness (area density) of the CNF interlayer exists. The difference in the effect of the interlayer fracture properties under mode II deformation was discussed on the bases of fractographic observations derived from scanning electric microscope.

Effect of Carbon Milled Fiber Addition on Interlaminar Fracture Toughness of Carbon Fiber Reinforced Plastics

2013 ◽  
Vol 577-578 ◽  
pp. 73-76 ◽  
Author(s):  
Hideaki Katogi ◽  
Kenichi Takemura
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Epoxy Resin ◽  
Mode I ◽  
Mode Ii ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics

In this study, effect of Carbon Milled Fiber (CMF) addition on interlaminar fracture toughness of carbon fiber reinforced plastics (CFRP) was investigated. Plain woven carbon fiber was used as reinforcement. Epoxy resin was used as matrix. The addition amounts of CMF are 0.5wt%, 0.8wt%, 1.0wt% and 1.2wt% for the epoxy resin. Mode I and mode II interlaminar fracture toughness tests were conducted based on JIS K 7086. As a result, mode I and mode II interlaminar fracture toughness increased with an increase of addictive amount of CMF. But excess addition was not effective. Pull out of CMF in matrix was found after mode I and mode II interlaminar fracture toughness tests. The mode I and mode II interlaminar fracture toughness of CMF added CFRP can be improved by fiber bridging of CMF.

EFFECTS OF TEMPERATURE ENVIRONMENT ON MODE II INTERLAMINAR FRACTURE TOUGHNESS IN ASYMMETRIC CFRP LAMINATES

2021 ◽  
Author(s):  
RYOSUKE IWAMA ◽  
HIROSHI SAITO ◽  
ISAO KIMPARA
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanism ◽  
Coupling Effect ◽  
Mode Ii ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture ◽  
Cfrp Laminates ◽  
Out Of Plane ◽  
Practical Temperature ◽  
Coupling Components

When delamination occurs in CFRP laminates due to impact, a portion of the laminate structure becomes asymmetric across the delamination in the thickness direction, resulting in a coupling effect of in-plane and out-of-plane deformations. Thus, it is important to evaluate the coupling effects on the interlaminar fracture toughness and fracture mechanism in CFRP laminates. In addition, it is necessary to withstand practical temperature environments. Based on Verchery's approach, the authors intentionally prepared asymmetric laminates with non-zero and zero-coupling components in the classical lamination theory to evaluate the effects of coupling components on the interlaminar fracture toughness in CFRP laminates. In this study, the Mode II interlaminar fracture toughness of CFRP laminates with and without coupling components in the stiffness matrix was measured by the end notched flexure (ENF) test in the temperature range from room temperature to 80°C. The relationship between the temperature and the interlaminar fracture toughness was quantitatively evaluated. Fracture surface observation was also conducted to clarify the fracture mechanism.

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