Tuning Interlaminar Fracture Toughness of Fine Z-Pin Reinforced Polymer Composite

Carbon fiber-reinforced polymer composites have been widely used in the aerospace industry. However, they are extremely sensitive to crack initiation, propagation and interlaminar delamination which severely reduce their service life. This paper demonstrated that the Mode-I interlaminar fracture toughness could be significantly improved in carbon fiber/bismaleimide composites using a microwave curing process. An increase of about 53.5% in critical load and an increase of approximately 133.5% and 61.2% in fracture toughness and fracture resistance have been achieved, respectively. The microwave manufacturing cycle for composites was cut to 44% of the thermal processing cycle. Dynamic mechanical thermal analysis was performed to investigate the enhanced interfacial strength in microwave-cured composites. The improvement in fracture toughness was attributed to a better interfacial adhesion between resin and fiber, which was investigated by the observation of fracture surfaces with optical microscopes.

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Enhancement of the Interlaminar Fracture Toughness of a Carbon-Fiber-Reinforced Polymer Using Interleaved Carbon Nanotube Buckypaper

Applied Sciences ◽

10.3390/app11156821 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6821

Author(s):

Yong-Chul Shin ◽

Seung-Mo Kim

Keyword(s):

Fracture Toughness ◽

Shear Strength ◽

Carbon Nanotube ◽

Fiber Reinforced Polymer ◽

Carbon Fiber Reinforced Polymer ◽

Mode Ii ◽

Interlaminar Fracture Toughness ◽

Plane Shear ◽

Interlaminar Fracture ◽

Reinforced Polymer

In this study, a carbon nanotube (CNT) buckypaper was interleaved in a carbon-fiber-reinforced polymer (CFRP) composite to improve the interlaminar fracture toughness. Interleaving the film of a laminate-type composite poses the risk of deteriorating the in-plane mechanical properties. Therefore, the in-plane shear modulus and shear strength were measured prior to estimating the interlaminar fracture toughness. To evaluate the effect of the buckypaper on the interlaminar fracture toughness of the CFRP, double cantilever beam (DCB) and end notch flexure (ENF) tests were conducted for mode I and mode II delamination, respectively. No significant change was observed for the in-plane shear modulus due to the buckypaper interleaving and the shear strength decreased by 4%. However, the interlaminar fracture toughness of the CFRP increased significantly. Moreover, the mode II interlaminar fracture toughness of the CFRP increased by 45.9%. Optical micrographs of the cross-section of the CFRPs were obtained to compare the microstructures of the specimens with and without buckypaper interleaving. The fracture surfaces obtained after the DCB and ENF tests were examined using a scanning electron microscope to identify the toughening mechanism of the buckypaper-interleaved CFRP.

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Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites

10.1520/d5528 ◽

2008 ◽

Cited By ~ 9

Author(s):

Keyword(s):

Fracture Toughness ◽

Polymer Matrix ◽

Polymer Matrix Composites ◽

Test Method ◽

Fiber Reinforced Polymer ◽

Mode I ◽

Matrix Composites ◽

Interlaminar Fracture Toughness ◽

Interlaminar Fracture ◽

Reinforced Polymer

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Mode II interlaminar fracture toughness of unidirectional fiber-reinforced polymer matrix composites with synthetic boehmite nanosheets at room temperature and low temperature

Journal of Composite Materials ◽

10.1177/0021998317716529 ◽

2017 ◽

Vol 52 (7) ◽

pp. 945-952 ◽

Cited By ~ 5

Author(s):

Xin Liu ◽

Tao Sun ◽

Zhanjun Wu ◽

Huiyong He

Keyword(s):

Fracture Toughness ◽

Carbon Fiber ◽

Fiber Reinforced Polymers ◽

Interlaminar Fracture Toughness ◽

Fiber Reinforced ◽

Carbon Fiber Reinforced Polymers ◽

Reinforced Polymers ◽

Interlaminar Fracture ◽

Reinforced Polymer ◽

Carbon Fiber Reinforced

The nanosheet boehmite (AlOOH) was synthesized and used as reinforcing agent to toughen carbon fiber-reinforced polymers. The purity, morphology, size and composition of the AlOOH nanosheets were investigated by the methods of XRD, SEM, TEM and FTIR, respectively. Interlaminar fracture toughness for mode II deformation was investigated for carbon fiber-reinforced polymers toughened by AlOOH nanosheets varying the contents at room temperature (RT, 293k) and at low temperature (LT, 77k). The fracture surfaces were examined by SEM to correlate with the interlaminar fracture properties. The results indicated that the synthesized AlOOH nanosheets were pure crystalline and of high purity. By TEM, the thickness of the lamellar AlOOH sample is about 22 nm. The end-notched flexure test results show that interlaminar fracture toughness of unidirectional carbon fiber-reinforced polymer with the same content AlOOH nanosheets (0, 1, 1.5, 2, 2.5, 3 wt.%) at LT is higher than that at RT. The interlaminar fracture toughness reaches the highest when the AlOOH nanosheets content equals 2% at RT. But at LT, the highest interlaminar fracture toughness appeared in the carbon fiber-reinforced polymers without AlOOH nanosheets.

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