A study on validity of using average fiber aspect ratio for mechanical properties of aligned short fiber composites with different fiber aspect ratios

2007 ◽  
Vol 78 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Jae-Kon Lee
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Fiber Composites ◽  
Short Fiber ◽  
Fiber Aspect Ratio ◽  
Aspect Ratios

Mechanical Properties of Electrospun Carbon Nano Fiber (ECNF)/Epoxy Nanocomposites

2007 ◽  
Author(s):  
Darunee Aussawasathien ◽  
Erol Sancaktar
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Epoxy Resin ◽  
Carbon Nanofiber ◽  
Mechanical Analysis ◽  
Short Fiber ◽  
Neat Epoxy ◽  
Epoxy Nanocomposites ◽  
Cure Reaction ◽  
Fiber Aspect Ratio

Electrospun polyacrylonitrile (PAN) fiber precursor based Carbon Nanofiber (CNF) mats were produced and impregnated with epoxy resin. The mechanical properties of as-prepared nanofibers in the mat and short fiber filled epoxy nanocomposite forms were determined to demonstrate the effect of fiber aspect ratio and interconnecting network on those properties. Our experimental results reveal that epoxy nanocomposites containing Electrospun Carbon Nano Fibers (ECNF) with high fiber aspect ratio and high interconnecting network in the non-woven mat form yield better mechanical properties than those filled with short ECNFs. The ECNF mat in epoxy nanocomposites provides better homogeneity, more interlocking network, and easier preparation than short ECNFs. Mechanical properties of ECNF mat-epoxy nanocomposites, which we obtained using tensile and flexural tests, such as stiffness and modulus increased, while toughness and flexural strength decreased, compared to the neat epoxy resin. Dynamic Mechanical Analysis (DMA) results showed, higher modulus for ECNF mat-epoxy nanocomposites, compared to those for neat epoxy resin and short ECNF-epoxy nanocomposites. The epoxy nanocomposites had high modulus, even though the glass transition temperature, Tg values dropped at some extents of ECNF mat contents when compared with the neat epoxy resin. The cure reaction was retarded since the amount of epoxy and hardener decreased at high ECNF contents together with the hindering effect of the ECNF mat to the diffusion of epoxy resin and curing agent, leading to low crosslinking efficiency.

Damping Properties of Vapor-Grown Carbon Fiber Composites

2000 ◽  
Author(s):  
Ioana C. Finegan ◽  
Gary G. Tibbetts ◽  
Ronald F. Gibson
Keyword(s):  
Carbon Fiber ◽  
Dynamic Properties ◽  
Fiber Composites ◽  
Dynamic Mechanical Properties ◽  
Short Fiber ◽  
Thermoplastic Composites ◽  
Carbon Fiber Composites ◽  
Fiber Aspect Ratio ◽  
Aspect Ratios ◽  
Injection Molded

Abstract The objective of this paper is to investigate analytically and experimentally the dynamic mechanical properties of vapor grown carbon fiber (VGCF)/thermoplastic composites. The experimental results show that, as predicted, very low fiber aspect ratios may produce significant improvements in damping. Since VGCF have submicron diameters and lengths, with a fiber aspect ratio, l/d = 19, good dynamic properties are obtained by using them as reinforcement in a thermoplastic. Fiber length distributions and orientation in the injection molded samples are determined by scanning electron microscopy (SEM). An analytical model based on the elastic-viscoelastic correspondence principle is developed to predict elastic properties in short fiber composites having a preferential fiber orientation in the direction of injection. The mechanical damping and storage modulus are analyzed experimentally by using a Dynamic Mechanic Analyzer (DMA).

scholarly journals Effects of Steel Fiber Percentage and Aspect Ratios on Fresh and Harden Properties of Ultra-High Performance Fiber

2021 ◽  
Vol 2 (3) ◽  
pp. 501-515
Author(s):  
Rajib Kumar Biswas ◽  
Farabi Bin Ahmed ◽  
Md. Ehsanul Haque ◽  
Afra Anam Provasha ◽  
Zahid Hasan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
High Performance ◽  
Steel Fiber ◽  
Setting Time ◽  
Fiber Reinforced Concrete ◽  
Future Research ◽  
Manufacturing Cost ◽  
Aspect Ratios ◽  
High Performance Fiber

Steel fibers and their aspect ratios are important parameters that have significant influence on the mechanical properties of ultrahigh-performance fiber-reinforced concrete (UHPFRC). Steel fiber dosage also significantly contributes to the initial manufacturing cost of UHPFRC. This study presents a comprehensive literature review of the effects of steel fiber percentages and aspect ratios on the setting time, workability, and mechanical properties of UHPFRC. It was evident that (1) an increase in steel fiber dosage and aspect ratio negatively impacted workability, owing to the interlocking between fibers; (2) compressive strength was positively influenced by the steel fiber dosage and aspect ratio; and (3) a faster loading rate significantly improved the mechanical properties. There were also some shortcomings in the measurement method for setting time. Lastly, this research highlights current issues for future research. The findings of the study are useful for practicing engineers to understand the distinctive characteristics of UHPFRC.

Modeling the Large Deformation and Microstructure Evolution of Nonwoven Polymer Fiber Networks

2018 ◽  
Vol 86 (1) ◽  
Author(s):  
Mang Zhang ◽  
Yuli Chen ◽  
Fu-pen Chiang ◽  
Pelagia Irene Gouma ◽  
Lifeng Wang
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Mechanical Behavior ◽  
Large Deformation ◽  
Biological Tissues ◽  
High Porosity ◽  
Polymer Fiber ◽  
Fiber Networks ◽  
Fiber Aspect Ratio ◽  
Network Microstructure

The electrospinning process enables the fabrication of randomly distributed nonwoven polymer fiber networks with high surface area and high porosity, making them ideal candidates for multifunctional materials. The mechanics of nonwoven networks has been well established for elastic deformations. However, the mechanical properties of the polymer fibrous networks with large deformation are largely unexplored, while understanding their elastic and plastic mechanical properties at different fiber volume fractions, fiber aspect ratio, and constituent material properties is essential in the design of various polymer fibrous networks. In this paper, a representative volume element (RVE) based finite element model with long fibers is developed to emulate the randomly distributed nonwoven fibrous network microstructure, enabling us to systematically investigate the mechanics and large deformation behavior of random nonwoven networks. The results show that the network volume fraction, the fiber aspect ratio, and the fiber curliness have significant influences on the effective stiffness, effective yield strength, and the postyield behavior of the resulting fiber mats under both tension and shear loads. This study reveals the relation between the macroscopic mechanical behavior and the local randomly distributed network microstructure deformation mechanism of the nonwoven fiber network. The model presented here can also be applied to capture the mechanical behavior of other complex nonwoven network systems, like carbon nanotube networks, biological tissues, and artificial engineering networks.

The Structure and the Mechanical Properties of a Newly Fabricated Cellulose-Nanofiber/Polyvinyl-Alcohol Composite

2014 ◽  
Vol 1621 ◽  
pp. 149-154
Author(s):  
Yukako Oishi ◽  
Atsushi Hotta
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Cellulose Nanofibers ◽  
Small Diameter ◽  
Short Fiber ◽  
Cellulose Nanofiber ◽  
Process Conditions ◽  
Aspect Ratios

ABSTRACTCellulose nanofibers (Cel-F) were extracted by a simple and harmless Star Burst (SB) method, which produced aqueous cellulose-nanofiber solution just by running original cellulose beads under a high pressure of water in the synthetic SB chamber. By optimizing the SB process conditions, the cellulose nanofibers with high aspect ratios and the small diameter of ∼23 nm were obtained, which was confirmed by transmission electron microscopy (TEM). From the structural analysis of the Cel-F/PVA composite by the scanning electron microscopy (SEM), it was found that the Cel-F were homogeneously dispersed in the PVA matrix. Considering the high molecular compatibility of the cellulose and PVA due to the hydrogen bonding, a good adhesive interface could be expected for the Cel-F and the PVA matrix. The influences of the morphological change in Cel-F on the mechanical properties of the composites were analysed. The Young’s modulus rapidly increased from 2.2 GPa to 2.9 GPa up to 40 SB treatments (represented by the unit Pass), whereas the Young’s modulus remained virtually constant above 40 Pass. Due to the uniform dispersibility of the Cel-F, the Young’s modulus of the 100 Pass composite at the concentration of 5 wt% increased up to 3.2 GPa. The experimental results corresponded well with the general theory of the composites with dispersed short-fiber fillers, which clearly indicated that the potential of the cellulose nanofibers as reinforcement materials for hydrophilic polymers was sufficiently confirmed.

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