scholarly journals Ballistic Impact Resistance of UHPC Plates Made with Hybrid Fibers and Low Binder Content

2021 ◽  
Vol 13 (23) ◽  
pp. 13410
Author(s):  
Paulo Rodrigo Dapper ◽  
Hinoel Zamis Ehrendring ◽  
Fernanda Pacheco ◽  
Roberto Christ ◽  
Giovanna Costella Menegussi ◽  
...  
Keyword(s):  
Impact Strength ◽  
Impact Energy ◽  
High Performance Concrete ◽  
Energy Levels ◽  
Ballistic Impact ◽  
Fiber Content ◽  
Thin Plates ◽  
Class Iii ◽  
Hybrid Fibers ◽  
Fiber Volume

This study assesses the ballistic impact strength of thin plates made of ultra-high-performance concrete (UHPC) with low cement content (250 kg/m3) and volumes of 80% steel and 20% polypropylene (PP) hybrid fibers. The plates were prepared with thicknesses of 30, 50, and 70 mm and fiber volume ratios of 1.5% and 3.0%. Compressive strength, flexural tensile strength, residual strength, and ballistic impact strength were determined using experimental methods. Test results showed that regardless of fiber content, the UHPC specimens prepared with the hybrid fibers showed similar performance against ballistic impact, exerting relatively low impact energy below 1000 J. The UHPC3.0 mixture made with 3.0% hybrid fiber content exhibited the best performance in terms of energy absorption and spalling resistance at impact energy levels greater than 4000 J. Plate sections with thicknesses of 7 mm showed class III performance (highest level), as recommended for military-based applications.

Impact Strength of Carbon Reinforced Epoxy Composite at Different Temperatures

2011 ◽  
Vol 264-265 ◽  
pp. 451-456 ◽  
Author(s):  
T.A. Lenda ◽  
S. Mridha
Keyword(s):  
Impact Strength ◽  
Impact Energy ◽  
Epoxy Composite ◽  
Charpy Impact ◽  
Fiber Content ◽  
Matrix Cracking ◽  
Fiber Volume ◽  
Fiber Splitting ◽  
Different Temperatures ◽  
The Impact

Charpy impact tests were conducted on carbon reinforced epoxy composites fabricated by hand lay-up method using 0.47, 0.56 and 0.66 carbon fiber volume fractions; tests were conducted at temperatures between -60oC to 60oC. The impact strength was found, in general, to increase when the samples were fractured at temperatures above 0oC and the impact strength decreased with the increase of fiber content. The impact energy absorption was highest of 270 KJm-2 with 47 vol% fiber when fractured at +60oC and it reduced to 130 KJm-2 at -60oC. With decreasing the fracture temperature and increasing the fiber content the impact strength reduced significantly. The reduction of impact energy was from 235 KJm-2 to 107 KJm-2 for 56 vol% fiber and from 196 KJm-2 to 90 KJm-2 for 66 vol% fiber when fractured at +60oC and -60oC, respectively. Failure occurred mostly by fiber delamination; fiber splitting and matrix cracking were also present. Delamination was more in specimens tested at -60oC while fiber splitting and matrix cracking were more when fractured at +60oC.

Influence of Moisture Absorption on Impact Strength and Failure Behavior of Hybrid Jute-Carbon/ Epoxy Composite

2011 ◽  
Vol 264-265 ◽  
pp. 457-462 ◽  
Author(s):  
T.A. Lenda ◽  
S. Mridha
Keyword(s):  
Impact Strength ◽  
Moisture Content ◽  
Immersion Time ◽  
Moisture Absorption ◽  
Water Immersion ◽  
Fiber Content ◽  
Failure Behavior ◽  
Fiber Volume ◽  
Volume Fractions ◽  
Fiber Fractions

Hybrid jute-carbon/ epoxy composites, fabricated by hand lay-up method with fiber volume fractions of 0.47, 0.58 and 0.68 were used to investigate water absorption behavior as a function of immersion time and fiber content. The effect of moisture content on impact strength and failure modes was also studied. Results show that the moisture absorption increased with increasing the immersion time in water and it was more with higher fiber fraction specimens. Maximum moisture contents of 0.45%, 0.52% and 0.61% were recorded for the specimens containing fiber volume fractions of 0.47, 0.58 and 0.68, respectively. The impact strength reduced with increasing moisture absorption in all specimens containing different fiber fractions. Composites with higher fiber content gave reduced impact strength under all test conditions. Composites of different fiber fractions and of highest moisture content produced impact strengths about 20 to 28% less than those strengths obtained without water immersion. The 47 vol% fiber specimen was least affected by water immersion and impact strength reduction was only 17% after immersion till saturation. Failure occurred by mainly by delamination and it was evident in all fractured specimens. Results of the effect of impact energy on moisture content have been evaluated using ANOVA ANALYSIS and the results gave errors of 1%, 0.6 % and 0.8 % for 0.47, 0.58 and 0.68 fiber volume fraction specimens, respectively.

scholarly journals Closed head injury in rats: histopathological aspects in an experimental weight drop model

2012 ◽  
Vol 27 (4) ◽  
pp. 290-294 ◽  
Author(s):  
Danilo dos Santos Silva ◽  
José Nazareno Pearce de Oliveira Brito ◽  
Jerúsia Oliveira Ibiapina ◽  
Marcel Fernando Miranda Batista Lima ◽  
Andréa Ribeiro Gonçalves de Vasconcelos Medeiros ◽  
...  
Keyword(s):  
Weight Loss ◽  
Head Injury ◽  
Impact Energy ◽  
Energy Levels ◽  
Closed Head Injury ◽  
Close Relation ◽  
Histopathological Analysis ◽  
Group 4 ◽  
Closed Head ◽  
Male Wistar Rats

PURPOSE: To study histopathological findings due to a model of closed head injury by weight loss in rats. METHODS: A platform was used to induce closed cranial lesion controlled by weight loss with a known and predefined energy. 25 male Wistar rats (Rattus novergicus albinus) were divided in five equal groups which received different cranial impact energy levels: G1, G2, G3 and G4 with 0.234J, 0.5J, 0.762J and 1J respectively and G5 (Sham). Under the effect of analgesia, the brain of each group was collected and prepared for histopathological analysis by conventional optic microscopy. RESULTS: It was observed greater number of injured neurons in animals of group 4, however neuronal death also could be noticed in animals of group 5. Intraparenchymal hemorrhages were more frequent in animals of group 4 and the cytotoxic brain swelling and vascular congestion were more intense in this group CONCLUSION: The histopathological analysis of these findings allowed to observe typical cranial trauma alterations and these keep close relation with impact energy.

Impact Damage Detection in GFRP Laminates through Ultrasonic Imaging

2012 ◽  
Vol 585 ◽  
pp. 337-341 ◽  
Author(s):  
H. Rama Murthy Naik ◽  
J. Jerald ◽  
N. Rajesh Mathivanan
Keyword(s):  
Impact Energy ◽  
Ultrasonic Testing ◽  
Energy Levels ◽  
Low Velocity Impact ◽  
Image Processing Technique ◽  
Sound Waves ◽  
Low Velocity ◽  
Immersion Method ◽  
Pulse Echo ◽  
The Impact

Composite materials are increasingly used in aerospace, naval and automotive vehicles due to their high specific strength and stiffness. In the area of Non destructive testing, ultrasonic C-scans are used frequently to detect defects in composite components caused during fabrication and damage resulting from service conditions. Ultrasonic testing uses transmission of high frequency sound waves into a material to detect imperfections or to locate changes in material properties. The most commonly used ultrasonic testing technique is pulse echo and through transmission wherein sound is introduced into a test object and reflections (echoes) are returned to a receiver from internal imperfections. Under low-velocity impact loading delaminating is observed to be a major failure mode. This report presents the use of above two techniques to detect the damage in glass fiber reinforced plastic (GFRP) laminates. Pulse echo is used to locate the exact position of damage and through transmission is used to know the magnitude of damage in composite. This paper work will be carried out on two different thicknesses and at impact energy levels varying from 7 to 53J. The ensuring delamination damage will be determined by ultrasonic C-scans using the pulse-echo immersion method for through transmission. Delamination areas were quantified accurately by processing the raw image data using a digital image processing technique. Based on the data obtained, correlation will be established between the delamination area and the impact energy.

scholarly journals Influence of Fiber Volume Fraction and Fiber Orientation on the Uniaxial Tensile Behavior of Rebar-Reinforced Ultra-High Performance Concrete

Fibers ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 67 ◽  
Author(s):  
Manish Roy ◽  
Corey Hollmann ◽  
Kay Wille
Keyword(s):  
Fiber Orientation ◽  
High Performance ◽  
Fiber Volume Fraction ◽  
High Performance Concrete ◽  
Volume Fraction ◽  
Tensile Behavior ◽  
Uniaxial Tensile ◽  
Ultra High Performance Concrete ◽  
Load Direction ◽  
Fiber Volume

This paper studied the influence of fiber volume fraction ( V f ), fiber orientation, and type of reinforcement bar (rebar) on the uniaxial tensile behavior of rebar-reinforced strain-hardening ultra-high performance concrete (UHPC). It was observed that the tensile strength increased with the increase in V f . When V f was kept constant at 1%, rebar-reinforced UHPC with fibers aligned with the load direction registered the highest strength and that with fibers oriented perpendicular to the load direction recorded the lowest strength. The strength of the composite with random fibers laid in between. Moreover, the strength, as well as the ductility, increased when the normal strength grade 60 rebars embedded in UHPC were replaced with high strength grade 100 rebars with all other conditions remaining unchanged. In addition, this paper discusses the potential of sudden failure of rebar-reinforced strain hardening UHPC and it is suggested that the composite attains a minimum strain of 1% at the peak stress to enable the members to have sufficient ductility.

Mechanical Behavior of Intercalated Polycarbonate Layered-Silicate Nanocomposites

2002 ◽  
Vol 733 ◽  
Author(s):  
Alex J. Hsieh ◽  
Donovan Harris ◽  
Paul Moy ◽  
John W. Song
Keyword(s):  
Impact Strength ◽  
Adhesive Bonding ◽  
Mechanical Response ◽  
Layered Silicate ◽  
Mechanical Deformation ◽  
Ballistic Impact ◽  
Impact Testing ◽  
Compressive Yield Strength ◽  
Clay Loading ◽  
Static Tensile

AbstractThe effect of layered-silicates on the mechanical response of intercalated polycarbonate (PC) nanocomposites subjected to quasi-static tensile, compressive and ballistic impact testing conditions has been investigated. These nanocomposites were melt-processed, in which good dispersion of nanoclays and adequate adhesive bonding between the nanoclay and PC matrix are achieved. However, their ductility upon tensile loading is significantly affected; a transition from ductile to brittle deformation occurs at clay loading of about 3 wt.%. Stress whitening is evident in the tensile- and ballistic-tested 1.5, 2.5, and 3.5 wt.% clay nanocomposites, and is attributed to the light scattering by microvoids, which are presumably formed from either crazing of PC or debonding of the nanoclay tactoids upon mechanical deformation. The effect of clay loading on the ballistic impact strength of the monolithic PC nanocomposites and layered PC/PC-nano/PC composites is determined. Compressive yield strength measurements are obtained at strain rate of 0.001/s for the monolithic PC nanocomposites and are utilized to correlate with the ballistic impact strength of the layered PC/PC-nano/PC composites. Thermal degradation is noted in these PC nanocomposites, and its effect on the mechanical deformation is briefly discussed.

scholarly journals Characterization of Hybrid Oil Palm Empty Fruit Bunch/Woven Kenaf Fabric-Reinforced Epoxy Composites

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2052
Author(s):  
Farah Hanan ◽  
Mohammad Jawaid ◽  
Md Tahir Paridah ◽  
Jesuarockiam Naveen
Keyword(s):  
Impact Strength ◽  
Oil Palm ◽  
Failure Modes ◽  
Fiber Content ◽  
Epoxy Composites ◽  
Void Content ◽  
Empty Fruit Bunch ◽  
Kenaf Fiber ◽  
The Impact ◽  
Woven Kenaf

In this research, the physical, mechanical and morphological properties of oil palm empty fruit bunch (EFB) mat/woven kenaf fabric-reinforced epoxy composites have been investigated. The oil palm EFB/woven kenaf fabrics were varied, with weight ratios of 50/0 (T1), 35/15 (T2), 25/25 (T3), 15/35 (T4) and 0/50 (T5). The composites were fabricated using a simple hand lay-up technique followed by hot pressing. The result obtained shows that an increase in kenaf fiber content exhibited higher tensile and flexural properties. On the other hand, the opposite trend was observed in the impact strength of hybrid composites, where an increase in kenaf fiber content reduced the impact strength. This can be corroborated with the physical properties analysis, where a higher void content, water absorption and thickness swelling were observed for pure oil palm EFB (T1) composites compared to other samples. The scanning electron microscopy analysis results clearly show the different failure modes of the tensile fractured samples. Statistical analysis was performed using one-way ANOVA and shows significant differences between the obtained results.

Effect of Fiber Content on Void Morphology in Resin Transfer Molded E-Glass/Epoxy Composites

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Youssef K. Hamidi ◽  
Sudha Dharmavaram ◽  
Levent Aktas ◽  
M. Cengiz Altan
Keyword(s):  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Void Formation ◽  
Areal Density ◽  
Fiber Content ◽  
Epoxy Composites ◽  
Formation Mechanisms ◽  
Liquid Composite Molding ◽  
Fiber Volume ◽  
Composite Molding

Effect of fiber volume fraction on occurrence, morphology, and spatial distribution of microvoids in resin transfer molded E-glass/epoxy composites is investigated. Three disk-shaped center-gated composite parts containing 8, 12, and 16 layers of randomly-oriented, E-glass fiber perform are molded, yielding 13.5%, 20.5%, and 27.5% fiber volume fractions. Voids are evaluated by microscopic image analysis of the samples obtained along the radius of these disk-shaped composites. The number of voids is found to decrease moderately with increasing fiber content. Void areal density decreased from 10.5 voids/mm2 to 9.5 voids/mm2 as fiber content is increased from 13.5% to 27.5%. Similarly, void volume fraction decreased from 3.1% to 2.5%. Increasing fiber volume fraction from 13.5% to 27.5% is found to lower the contribution of irregularly-shaped voids from 40% of total voids down to 22.4%. Along the radial direction, combined effects of void formation by mechanical entrapment and void mobility are shown to yield a spatially complex void distribution. However, increasing fiber content is observed to affect the void formation mechanisms as more voids are able to move toward the exit vents during molding. These findings are believed to be applicable not only to resin transfer molding but generally to liquid composite molding processes.

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