MECHANICAL PERFORMANCE OF CARBON - ARAMID FIBER-REINFORCED LAMINATED COMPOSITES UNDER IMPACT AND SHEAR LOADING

Fiber-reinforced epoxy sandwich composites, which were designed as the bonded repair patches to better recover the mechanical performance of a central cracked aluminum alloy plate, were layered by carbon and aramid fiber layers jointly and cured by microwave method in this study. The static tensile and bending properties of both carbon-aramid fiber/epoxy sandwich composite patches and the cracked aluminum alloy plates after bonded repair were systematically investigated. By comparing the mechanical performance with traditional single carbon-fiber-reinforced composite patches, it can be found that the bending performance of carbon-aramid fiber sandwich composite patches was effectively improved after incorporation of flexible aramid fiber layers into the carbon fiber layers, but the tensile strength of sandwich composite patches was weakened to some extent. Especially, the sandwich patches with 3 fiber layers exhibited better tensile and bending performance in comparison to patches of 5 and 7 fiber layers. The optimized 3-layer carbon-aramid fiber sandwich patch repaired plate recovered 86% and 190% of the tensile and bending performance in comparison to the uncracked ones, respectively, showing a considerable repair majorization effect for the cracked aluminum alloy plate.

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Preparation of Long Sisal Fiber-Reinforced Polylactic Acid Biocomposites with Highly Improved Mechanical Performance

Polymers ◽

10.3390/polym13071124 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1124

Author(s):

Zhifang Liang ◽

Hongwu Wu ◽

Ruipu Liu ◽

Caiquan Wu

Keyword(s):

Mechanical Properties ◽

Polylactic Acid ◽

Mechanical Performance ◽

Tensile Elongation ◽

Sisal Fiber ◽

Fiber Reinforced ◽

Impact Performance ◽

The Matrix ◽

Blending Process ◽

Extension Direction

Green biodegradable plastics have come into focus as an alternative to restricted plastic products. In this paper, continuous long sisal fiber (SF)/polylactic acid (PLA) premixes were prepared by an extrusion-rolling blending process, and then unidirectional continuous long sisal fiber-reinforced PLA composites (LSFCs) were prepared by compression molding to explore the effect of long fiber on the mechanical properties of sisal fiber-reinforced composites. As a comparison, random short sisal fiber-reinforced PLA composites (SSFCs) were prepared by open milling and molding. The experimental results show that continuous long sisal fiber/PLA premixes could be successfully obtained from this pre-blending process. It was found that the presence of long sisal fibers could greatly improve the tensile strength of LSFC material along the fiber extension direction and slightly increase its tensile elongation. Continuous long fibers in LSFCs could greatly participate in supporting the load applied to the composite material. However, when comparing the mechanical properties of the two composite materials, the poor compatibility between the fiber and the matrix made fiber’s reinforcement effect not well reflected in SSFCs. Similarly, the flexural performance and impact performance of LSFCs had been improved considerably versus SSFCs.

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Improved mechanical performances of short aramid fiber‐reinforced polypropylene composites by Ti 3 C 2 Mxene nanosheets

Polymer Composites ◽

10.1002/pc.25953 ◽

2021 ◽

Author(s):

Bolin Tang ◽

Yaru Yang ◽

Yicheng Shi ◽

Huijie Nie ◽

Hongqin Xia ◽

...

Keyword(s):

Aramid Fiber ◽

Fiber Reinforced ◽

Polypropylene Composites ◽

Mechanical Performances

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Mechanical properties of aramid fiber reinforced rubber sealing gasket at different temperatures

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/714/3/032079 ◽

2021 ◽

Vol 714 (3) ◽

pp. 032079

Author(s):

Bin Zhang ◽

Xiucheng Feng ◽

Cheng Yang ◽

Xiaoming Yu ◽

Jiawei Nie

Keyword(s):

Mechanical Properties ◽

Aramid Fiber ◽

Fiber Reinforced ◽

Different Temperatures

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Sulfone-functionalized poly(p-phenylene terephthalamide) copolymer fibers with improved interfacial adhesion to epoxy matrices

High Performance Polymers ◽

10.1177/09540083211008955 ◽

2021 ◽

pp. 095400832110089

Author(s):

Ting Li ◽

Zengxiao Wang ◽

Hao Zhang ◽

Yutong Cao ◽

Zuming Hu ◽

...

Keyword(s):

Interfacial Adhesion ◽

Interfacial Shear Strength ◽

Aramid Fiber ◽

Fiber Reinforced Composites ◽

Epoxy Composites ◽

Reinforced Composites ◽

Fiber Reinforced ◽

Regular Arrangement ◽

Epoxy Matrices ◽

Polymerization Conditions

The poor interfacial adhesion of aramid fiber and matrix limits the application of the final composites. In this study, a series of the sulfone-functionalized poly( p-phenylene terephthalamide) (SPPTA) copolymers were satisfactorily synthesized and the effects of polymerization conditions (contents of the additional monomer and the cosolvent LiCl, molar concentration and ratio of the monomer, reaction temperature and time) on the molecular weight of the copolymer were discussed. The introduction of the sulfone group in aromatic polyamides not only increased the polarity of poly( p-phenylene terephthalamide) (PPTA) but destroyed the regular arrangement of the molecular chains, which greatly improved the surface free energy and the solubility of the polymers in organic solvents. The polymer maintained excellent thermal and interfacial properties. Compared with the PPTA fiber/epoxy composites, the interfacial shear strength (IFSS) of SPPTA fiber-reinforced epoxy composites reached 43.5 MPa, with a significantly enhancement of 20.8%, implying that the study provided an effective method to achieve highly interfacial adhesion of aramid fiber-reinforced composites.

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Modeling of Bridging Law for Bundled Aramid Fiber-Reinforced Cementitious Composite and its Adaptability in Crack Width Evaluation

Materials ◽

10.3390/ma14010179 ◽

2021 ◽

Vol 14 (1) ◽

pp. 179

Author(s):

Daiki Sunaga ◽

Takumi Koba ◽

Toshiyuki Kanakubo

Keyword(s):

Fiber Orientation ◽

Crack Width ◽

Volume Fraction ◽

Characteristic Point ◽

Crack Opening ◽

Aramid Fiber ◽

Cementitious Composite ◽

Fiber Reinforced ◽

Cross Sectional ◽

Bridging Law

Tensile performance of fiber-reinforced cementitious composite (FRCC) after first cracking is characterized by fiber-bridging stress–crack width relationships called bridging law. The bridging law can be calculated by an integral calculus of forces carried by individual fibers, considering the fiber orientation. The objective of this study was to propose a simplified model of bridging law for bundled aramid fiber, considering fiber orientation for the practical use. By using the pullout characteristic of bundled aramid fiber obtained in the previous study, the bridging laws were calculated for various cases of fiber orientation. The calculated results were expressed by a bilinear model, and each characteristic point is expressed by the function of fiber-orientation intensity. After that, uniaxial tension tests of steel reinforced aramid-FRCC prism specimens were conducted to obtain the crack-opening behavior and confirm the adaptability of the modeled bridging laws in crack-width evaluation. The experimental parameters are cross-sectional dimensions of specimens and volume fraction of fiber. The test results are compared with the theoretical curves calculated by using the modeled bridging law and show good agreements in each parameter.

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