scholarly journals Interlaminar Fracture Behavior of Carbon Fiber/Polyimide Composites Toughened by Interleaving Thermoplastic Polyimide Fiber Veils

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2695
Author(s):  
Bangwei Lan ◽  
Yi Liu ◽  
Song Mo ◽  
Minhui He ◽  
Lei Zhai ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Fracture Behavior ◽  
Elevated Temperatures ◽  
Areal Density ◽  
Thermally Stable ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture ◽  
Maximum Improvement ◽  
Polyimide Composites

Carbon fiber reinforced thermosetting polyimide (CF/TSPI) composites were interleaved with thermally stable thermoplastic polyimide (TPPI) fiber veils in order to improve the interlaminar fracture toughness without sacrificing the heat resistance. Both of the mode I and mode II interlaminar fracture toughness (GIC and GIIC) for the untoughened laminate and TPPI fiber veils interleaved laminates were characterized by the double cantilever beam (DCB) test and end notch flexure (ENF) test, respectively. It is found that the TPPI fiber veils interleaved laminates exhibit extremely increased fracture toughness than the untoughened one. Moreover, the areal density of TPPI greatly affected the fracture toughness of laminates. A maximum improvement up to 179% and 132% on GIC and GIIC is obtained for 15 gsm fiber veils interleaved laminate, which contributes to the existence of bicontinuous TPPI/TSPI structure in the interlayer according to the fractography analysis. The interlaminar fracture behavior at elevated temperatures for 15 gsm fiber veils interleaved laminate were also investigated. The results indicated that the introduction of thermally stable TPPI fiber veils could enhance the fracture toughness of CF/TSPI composites by exceeding 200% as compared to the untoughened one even as tested at 250 °C.

Interlaminar fracture toughness and electromagnetic interference shielding of hybrid-stitched carbon fiber composites

2018 ◽  
Vol 37 (18) ◽  
pp. 1131-1141 ◽  
Author(s):  
Nisrin R Abdelal ◽  
Steven L Donaldson
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Electromagnetic Interference ◽  
Experimental Results ◽  
Mode I ◽  
Carbon Fiber Composites ◽  
Interlaminar Fracture Toughness ◽  
Shielding Effectiveness ◽  
Electromagnetic Interference Shielding ◽  
Interlaminar Fracture

In the current study, the production of multifunctional hybrid-stitched composites with improved interlaminar fracture toughness and electromagnetic interference shielding effectiveness is reported. Unidirectional carbon fiber-epoxy composite laminates stitched with Kevlar, nylon, hybrid stitched with both Kevlar and nylon and unstitched were prepared using resin infusion process. Representative specimens from unstitched and stitched composites were tested using rectangular waveguide and Mode I double cantilever beam tests. The Mode I experimental results showed that composite stitched with Kevlar exhibited the highest crack initiation interlaminar fracture toughness (GIC-initiation), whereas composite stitched with nylon exhibited the highest maximum crack propagation interlaminar fracture toughness (GIC-maximum). The four-hybrid stitching patterns exhibited higher GIC-initiation than the unstitched and stitched with nylon composites and lower than stitched with Kevlar composite, whereas they had higher GIC-maximum than the unstitched and stitched with Kevlar composites, although lower than stitched with nylon composite. The electromagnetic shielding effectiveness experimental results showed that stitched composites exhibited improved shielding effectiveness compared to unstitched composites. For example, composite stitched with nylon had highest shielding effectiveness value of 52.17 dB compared by the composite stitched with Kevlar which had 40.6 dB. The four hybrid-stitched composites exhibited similar shielding effectiveness with an average value of 32.75 dB compared to the unstitched composite shielding effectiveness of 22.84 dB. The experimental results comply with the initial goal of this study to manufacture multifunctional hybrid stitching composites with combined properties between Kevlar and nylon-stitched composites.

Interlaminar Fracture in Carbon Fiber/Thermoplastic Composites

1989 ◽  
Vol 170 ◽  
Author(s):  
J. A. Hinkley ◽  
W. D. Bascom ◽  
R. E. Allred
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
High Strain ◽  
Thermoplastic Composites ◽  
Plasma Modification ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture ◽  
Polyphenylene Oxide ◽  
Commercial Carbon

AbstractThe surfaces of commercial carbon fibers are generally chemically cleaned or oxidized and then coated with an oligomeric sizing to optimize their adhesion to epoxy matrix resins. Evidence from fractography, from embedded fiber testing and from fracture energies suggests that these standard treatments are relatively ineffective for thermoplastic matrices. This evidence is reviewed and model thermoplastic composites (polyphenylene oxide/high strain carbon fibers) are used to demonstrate how differences in adhesion can lead to a two-fold change in interlaminar fracture toughness.The potential for improved adhesion via plasma modification of fiber surfaces is discussed. Finally, a surprising case of fiber-catalyzed resin degradation is described.

scholarly journals Improving Interlaminar Fracture Toughness and Impact Performance of Carbon Fiber/Epoxy Laminated Composite by Using Thermoplastic Fibers

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3367 ◽  
Author(s):  
Ling Chen ◽  
Li-Wei Wu ◽  
Qian Jiang ◽  
Da Tian ◽  
Zhili Zhong ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Laminated Composite ◽  
Areal Density ◽  
Low Velocity Impact ◽  
Interlaminar Fracture Toughness ◽  
Low Velocity ◽  
Velocity Impact ◽  
Interlaminar Fracture ◽  
Impact Performance ◽  
Carbon Fiber Epoxy

The effects of thermoplastic polyimide (PI) and polypropylene (PP) fibers and areal density of toughened layer on interlaminar fracture toughness and impact performance of carbon fiber/epoxy (CF/EP) laminated composites were studied. Mode I interlaminar fracture toughness (GIC) was analyzed via double cantilever beam (DCB) tests. When comparing for the toughener type, PI played a positive role in enhancing the mode-I fracture toughness, while PP was not effective due to the less fiber bridge formed during composite curing. The toughening effects of areal density of PI were further investigated by end notched flexure (ENF) testing and low velocity impact testing to better understand the toughening mechanisms. The results revealed that the toughening effect reached its best effectiveness when the areal density of toughened layer was 30 g/m2. Compared with the control group, GIC and GIIC of CF/EP laminated composite were increased by 98.49% and 84.07%, and Fmax and Ee were enhanced by 92.38% and 299.08% under low velocity impact. There is no obvious delamination phenomenon on the surface of laminates after low velocity impact, indicating the improved interlaminar and impact performance of laminated composite.

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