Effect of Resin Layer Thickness on Mode II Delamination Growth Property of CFRTP Laminates under Static Loadings

2019 ◽  
Vol 827 ◽  
pp. 446-451
Author(s):  
Kazuto Tanaka ◽  
Kosuke Ishida ◽  
Keisuke Takemoto ◽  
Tsutao Katayama
Keyword(s):  
Fracture Toughness ◽  
Static Loading ◽  
Middle Layer ◽  
Mode Ii ◽  
Thermoplastic Resin ◽  
Growth Property ◽  
Cfrp Laminates ◽  
Delamination Growth ◽  
Resin Layer ◽  
Reinforced Thermoplastics

Carbon Fibre Reinforced Thermoplastics (CFRTP) are expected to be used in various fields for the point of their superior mechanical properties. CFRP laminates with continuous fibres tend to be damaged by microcracks in the layer and interlaminar delamination. Especially, it is necessary to evaluate the mode II delamination growth property, which is correlated with compression after impact (CAI) strength. It is reported that CF/Epoxy laminates with a thicker interlaminar resin layer show higher toughness. By applying an extra thick interlaminar resin layer to CFRTP in which thermoplastic resin with relatively higher fracture toughness is used for the matrix, CFRTP with higher interlaminar fracture toughness can be developed. In this study, the mode II delamination growth property of CFRTP laminates under static loading was evaluated for the specimens with various layer thicknesses of polyamide (PA) resin in the middle layer of the laminates. Their moldability and damage propagation properties were evaluated by three-point bending tests and end notched flexure (ENF) tests. CF/PA laminated composites with a thicker PA layer showed superior mode II delamination growth property under static loading since they had more ductile fracture due to a thicker PA layer.

2753 Mode I and Mode II Interlaminer Fracture Toughness of CFRP laminates Toughened by Carbon-nano-fiber

2007 ◽  
Vol 2007.1 (0) ◽  
pp. 667-668
Author(s):  
Masahiro ARAI ◽  
Kazutoshi MATSUSHITA ◽  
Koh-ichi SUGIMOTO ◽  
Morinobu ENDO
Keyword(s):  
Fracture Toughness ◽  
Mode I ◽  
Mode Ii ◽  
Cfrp Laminates ◽  
Nano Fiber

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.

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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