scholarly journals Hybrid Effect of Twisted Steel and Polyethylene Fibers on the Tensile Performance of Ultra-High-Performance Cementitious Composites

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 879 ◽  
Author(s):  
Min-Jae Kim ◽  
Soonho Kim ◽  
Doo-Yeol Yoo
Keyword(s):  
Tensile Strength ◽  
Aspect Ratio ◽  
High Performance ◽  
Performance Test ◽  
Volume Fraction ◽  
Synergetic Effect ◽  
Hybrid Effect ◽  
Strain Capacity ◽  
Aspect Ratios ◽  
Tensile Performance

The hybrid effect of twisted steel (T) fibers with an aspect ratio of 100 and polyethylene (PE) fibers with four different aspect ratios of 400, 600, 900, and 1200 on the mechanical performance of ultra-high-performance cementitious composite (UHPCC) was investigated. This involved a total of 17 different sample types at an identical fiber volume fraction of 2% being made and subjected to compressive and tensile loads. Samples were made by replacing 0.5%, 1.0%, 1.5%, and 2.0% of T fibers with four different types of PE fibers. In addition, the pullout behaviors of fibers at cracked sections and the cracking behaviors of specimens were evaluated in order to determine the effect of the pullout mechanism of each fiber on the overall tensile performance. Test results indicate that the compressive strength decreased in proportion to the amount of PE fibers, regardless of their aspect ratio. The fiber hybridization had a great synergetic effect, successfully improving the tensile strength and strain capacity of UHPCCs; this effect was dependent on the aspect ratio of the PE fibers. Finally, the cracking behaviors were determined to be more related to the fiber type and pullout mechanisms than the tensile strength or strain capacity of UHPCCs.

scholarly journals EFFECT OF FIBRE ASPECT RATIO AND FIBRE VOLUME FRACTION ON THE EFFECTIVE FRACTURE ENERGY OF ULTRA-HIGH-PERFORMANCE FIBRE-REINFORCED CONCRETE

2016 ◽  
Vol 56 (4) ◽  
pp. 319-327 ◽  
Author(s):  
Radoslav Sovják ◽  
Petr Máca ◽  
Tomáš Imlauf
Keyword(s):  
Aspect Ratio ◽  
Fracture Energy ◽  
High Performance ◽  
Volume Fraction ◽  
Linear Trend ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Aspect Ratios ◽  
Fibre Aspect Ratio ◽  
High Performance Fibre

<p>This paper investigates the effective fracture energy of UHPFRC with various fibre volume fractions and various fibre aspect ratios. We have concluded that the effective fracture energy is dependent on both the fibre volume fraction and the fibre aspect ratio. In addition, we have found that both dependencies follow a linear trend.</p>

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.

scholarly journals Strength Analysis of Alternative Airframe Layouts of Regional Aircraft on the Basis of Automated Parametrical Models

Aerospace ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 80
Author(s):  
Dmitry V. Vedernikov ◽  
Alexander N. Shanygin ◽  
Yury S. Mirgorodsky ◽  
Mikhail D. Levchenkov
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Performance ◽  
Strength Analysis ◽  
Labor Input ◽  
Aerodynamic Loading ◽  
Aspect Ratios ◽  
Wide Range ◽  
Parametrical Design

This publication presents the results of complex parametrical strength investigations of typical wings for regional aircrafts obtained by means of the new version of the four-level algorithm (FLA) with the modified module responsible for the analysis of aerodynamic loading. This version of FLA, as well as a base one, is focused on significant decreasing time and labor input of a complex strength analysis of airframes by using simultaneously different principles of decomposition. The base version includes four-level decomposition of airframe and decomposition of strength tasks. The new one realizes additional decomposition of alternative variants of load cases during the process of determination of critical load cases. Such an algorithm is very suitable for strength analysis and designing airframes of regional aircrafts having a wide range of aerodynamic concepts. Results of validation of the new version of FLA for a high-aspect-ratio wing obtained in this work confirmed high performance of the algorithm in decreasing time and labor input of strength analysis of airframes at the preliminary stages of designing. During parametrical design investigation, some interesting results for strut-braced wings having high aspect ratios were obtained.

Heatline and Massline Visualization of Hydromagnetic Double Diffusive Convective Flow of Nanofluid Within a Porous Trapezoidal Cavity

2021 ◽  
Vol 10 (2) ◽  
pp. 270-284
Author(s):  
Bikash C. Saha ◽  
T. R. Mahapatra ◽  
Dulal Pal
Keyword(s):  
Aspect Ratio ◽  
Convective Flow ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Temperature Fields ◽  
Computational Domain ◽  
Aspect Ratios ◽  
Numerical Predictions ◽  
Double Diffusive

Double diffusive convective flow of nanofluid within a porous trapezoidal cavity of various aspect ratios consisting of Al2O3 nanoparticle in the presence of applied magnetic field in the direction perpendicular to the parallel top and bottom walls is analysed. The side walls of the cavity are maintained at constant temperature and concentration while its horizontal walls are insulated and impermeable. The irregular physical domain of the problem is transformed to a regular unit square computational domain. The governing equations have been solved by second order of finite difference method (FDM). Based upon numerical predictions, the effects of pertinent parameters such as Rayleigh number, Darcy number, aspect ratio, solid volume fraction and inclination angle on the flow and temperature fields and the heat transfer performance of the enclosure are examined. It is found that the intensity of heat and mass transfer increases with the increase in the Darcy number and aspect ratio. It is also observed that as the solid volume fraction increases there is increase in the average Nusselt number but reverse effect is observed on the average Sherwood number.

Improving UV Resistance of Fibers: Idealized Computational Model Predicting the Distribution of UV Blocking Cylindrical Nanoparticles in Protective Polymeric Layer

2015 ◽  
Vol 10 (1) ◽  
pp. 155892501501000
Author(s):  
Abdelfattah Mohamed Seyam ◽  
Rahul Vallabh ◽  
Ahmed H. Hassanin
Keyword(s):  
Aspect Ratio ◽  
Computational Model ◽  
High Performance ◽  
Volume Fraction ◽  
Three Dimensional ◽  
High Strength ◽  
Uv Protection ◽  
Uv Resistance ◽  
Premature Failure ◽  
Areal Coverage

High strength fibers such as PBO and Kevlar are used to produce composites, bulletproof vests, tendons of giant scientific balloons, and other high performance products. These fibers, however, are known to degrade upon exposure to Ultraviolet (UV) radiation which causes premature failure of the end-products. Improving UV resistance of high strength fibers like PBO through methods such as adding UV inhibiting particles during filament spinning or dyeing/coating process is not only extremely difficult, but often fails to provide the adequate UV protection. As an alternative to conventional approaches, UV protection of high performance yarns/braids can be effectively achieved by covering them with a polymeric sheath containing dispersed UV inhibiting nanoparticles. In this work, a computational model was developed to optimize critical factors such as thickness (weight) of the protective sheath and the amount of UV blockers for a given particle size, which influence the UV protective efficiency of the sheath. In order to simulate three-dimensional dispersion of nanoparticles in a polymer matrix, the model considers a random distribution of cylindrical nanoparticles of different size, aspect ratio, and volume fraction in a three-dimensional volume of protective sheath of a given length, width, and thickness. 2D visualization and image analysis techniques were utilized to determine the area projected by the particles on the x-y plane (areal coverage provided by nanoparticles). The areal coverage values obtained from the model were found to be higher than the experimental results due to the agglomeration of nanoparticles in the sheath caused during the polymer compounding process. However, the purpose of the model is to serve as a benchmarking tool to aid in the design and development of UV protective sheaths and films, and not to estimate absolute UV protection values. Analysis of the relationship between areal coverage and various input parameters in the model show that areal coverage increases with an increase in particle volume fraction and film thickness, and a decrease in particle diameter and length. It was also found that areal coverage was more significantly influenced by particle aspect ratio than by particle length.

scholarly journals Effects of circular corners and aspect-ratio on entropy generation due to natural convection of nanofluid flows in rectangular cavities

2015 ◽  
Vol 19 (5) ◽  
pp. 1621-1632 ◽  
Author(s):  
Mahmoud Salari ◽  
Ali Mohammadtabar ◽  
Mohammad Mohammadtabar
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Bejan Number ◽  
Total Entropy ◽  
Aspect Ratios ◽  
Corner Radius

In this paper, entropy generation induced by natural convection of cu-water nanofluid in rectangular cavities with different circular corners and different aspect-ratios were numerically investigated. The governing equations were solved using a finite volume approach and the SIMPLE algorithm was used to couple the pressure and velocity fields. The results showed that the total entropy generation increased with the increase of Rayleigh number, irreversibility coefficient, aspect ratio or solid volume fraction while it decreased with the increase of the corner radius. It should be noted that the best way for minimizing entropy generation is decreasing Rayleigh number. This is the first priority for minimizing entropy generation. The other parameters such as radius, volume fraction, etc are placed on the second priority. However, Bejan number had an inverse trend compared with total entropy generation. As an exception, Bejan number and total entropy number had the same trend whenever solid volume fraction increased. Moreover, Nusselt number increased as Rayleigh number, solid volume fraction or aspect ratio increased whereas it decreases with the increase of corner radius.

Evaluation of Fundamental UHPC Properties According to the Shape of Steel Fiber

2010 ◽  
Vol 452-453 ◽  
pp. 717-720 ◽  
Author(s):  
Gum Sung Ryu ◽  
Su Tae Kang ◽  
Jung Jun Park ◽  
Kyung Taek Koh ◽  
Sung Wook Kim
Keyword(s):  
Aspect Ratio ◽  
Flexural Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Steel Fibers ◽  
Flexural Behavior ◽  
Ultra High Performance Concrete ◽  
Aspect Ratios ◽  
Strength Tests ◽  
Shaped Fibers

This paper intends to examine the effects if the length and shape of steel fibers on the mechanical characteristics of ultra-high performance concrete (UHPC). Accordingly, the length (l) of the steel fibers with diameter (d) of 0.2 mm is varied as 13 mm, 16.3 mm and 19.5 mm and their corresponding aspect ratios (l/d) are 65, 82 and 98. Straight and wave-shaped fibers are adopted to manufacture UHPC. Thereafter, the effects of the aspect ratio and characteristics of the wave-shape of the steel fibers on the strength characteristics of UHPC are examined through compressive and flexural strength tests. The results showed small differences in the workability and compressive behavior but revealed that changing the length of the fibers and increasing the aspect ratio are improving the flexural behavior of UHPC. Specifically, the flexural strength was enhanced by 25% and the flexural toughness by 30%. Compared to rectilinear fibers, the adoption of wave-shaped fibers is seen to degrade the flexural behavior regardless of the aspect ratio. Consequently, using straight steel fibers and adopting larger aspect ratio seems advisable to improve the toughness of UHPC.

Effect of Metakaolin and PVA Fibres on the Workability and Mechanical Properties of Concrete

2014 ◽  
Vol 935 ◽  
pp. 188-192 ◽  
Author(s):  
Sadaqat Ullah Khan ◽  
Muhd Fadhil Nuruddin ◽  
Nasir Shafiq ◽  
Tehmina Ayub
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Aspect Ratio ◽  
Volume Fraction ◽  
Splitting Tensile Strength

Locally produced metakaolin (MK) as the cement replacing material and PVA fibres has been used. The effect on workability and on the mechanical properties of concrete has been investigated. Total fifteen (15) mixes of concrete have been examined using MK 5 to 10% and PVA fibres of aspect ratio 45, 60, 90 and 120 with 1% volume fraction. Three (03) mixes without PVA fibre have been used as control mixes. For each mix, test for slump, cube compressive strength and splitting tensile strength has been performed. It has been found that MK and PVA fibres causes decrease in slump but use of MK and PVA fibres together improves the workability. The use of MK and PVA fibres has advantageous in increasing compressive strength and splitting tensile strength.

Tensile Strength and Impact Toughness of Gallium-Bearing Near-α Titanium Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 619-623 ◽  
Author(s):  
Tomonrori Kitashima ◽  
K.S. Suresh ◽  
Y. Yamabe-Mitarai ◽  
S. Iwasaki
Keyword(s):  
Tensile Strength ◽  
Impact Toughness ◽  
Titanium Alloys ◽  
Room Temperature ◽  
Volume Fraction ◽  
Charpy Impact ◽  
Minor Effect ◽  
Future Design ◽  
Aspect Ratios ◽  
A Minor

The present study aims to quantify the properties of Ga-bearing near-titanium alloys in order to aid the future design of new compositions with Ga addition. The effect of different amounts of Sn and Ga, with an almost constant value in the Al equivalent without the formation of 2 phase, on microstructure, tensile strength and Charpy impact toughness was investigated at room temperature and 650°C. The microstructures after forging, hot rolling and heat treatment showed a bimodal structure. Increasing Ga decreased the 0.2% proof stress at 650°C. However, these alloys showed similar impact value at room temperature which was about 40 J/cm2. Increasing the amount of Ga increased the volume fraction of the equiaxed phase. The amount of Ga had only a minor effect on grain size, misorientation angles and grain aspect ratios of the alloy. However, Ga addition had a strong influence on the evolution of texture. Formation of <10-10> and <10-11> || normal direction (ND) fibers were observed in the Ga added samples, in addition to <0001> || ND fiber with a weak <10-11> || ND fiber. The Ga-free sample contained a strong <0001> || ND fiber. Other fibers were not observed.

Performance Test of Swage Anchorage According to the Insert of CFRP Tendon

2017 ◽  
Vol 730 ◽  
pp. 452-456
Author(s):  
Moon Seoung Keum ◽  
Jae Yoon Kang ◽  
Jong Sup Park ◽  
Woo Tai Jung
Keyword(s):  
Experimental Study ◽  
Tensile Strength ◽  
Material Properties ◽  
Orthotropic Material ◽  
Performance Test ◽  
Outer Diameter ◽  
Conventional Steel ◽  
Tensile Performance ◽  
New Type ◽  
Improved Performance

Despite of the numerous advantages offered by the CFRP tendon, there are still problems to be solved. Among them, finding an effective anchoring method considering the material properties of CFRP constitutes a typically pending problem. Being an orthotropic material, the CFRP tendon presents risk of breakage under forces acting perpendicularly to the direction of the fibers. This implies that a new type of anchor should be developed for the CFRP tendon since the anchorages used for conventional steel strands cannot be readily applied. Moreover, following the growing interest given to the CFRP tendon, research is being relentlessly conducted to develop dedicated anchorages with improved performance. Accordingly, this paper presents an experimental study on the anchor performance of the swage anchorage known to be the most compact among the various types of anchor. The tests revealed that the swage anchor without insert developed about 92% of the tensile strength of the CFRP tendon whereas the swage anchor with metallic winding insert developed 100% of the tensile strength. From these results, it appears that the anchorage with outer diameter of 24 mm develops anchor performance higher than 95% of the tensile performance of the CFRP tendon and can potentially be exploited for post-tensioning.

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