scholarly journals Ballistic Performance of Guaruman Fiber Composites in Multilayered Armor System and as Single Target

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1203
Author(s):  
Raphael Henrique Morais Reis ◽  
Larissa Fernandes Nunes ◽  
Fernanda Santos da Luz ◽  
Verônica Scarpini Candido ◽  
Alisson Clay Rios da Silva ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Natural Fiber ◽  
Fiber Composite ◽  
Epoxy Composites ◽  
Ballistic Performance ◽  
Single Target ◽  
The Us ◽  
Lethal Limit ◽  
First Time ◽  
Armor System

Multilayered armor systems (MAS) with a front ceramic layer backed by a relatively unknown Amazonian guaruman fiber-reinforced (Ischnosiphon koem) epoxy composites, as second layer, were for the first time ballistic tested against the threat of 7.62 mm rifle ammunition. The amount of 30 vol% guaruman fibers was investigated in three distinct configurations: (i) continuous aligned, (ii) 0–90° cross-laid, and (iii) short-cut randomly dispersed. Additionally, single-target ballistic tests were also carried out in the best MAS-performed composite with cross-laid guaruman fibers against .22 caliber ammunition. The results disclosed that all composites as MAS second layer attended the US NIJ standard with corresponding penetration depth of (i) 32.9, (ii) 27.5, and (iii) 29.6 mm smaller than the lethal limit of 44 mm in a clay witness simulating a personal body. However, the continuous aligned guaruman fiber composite lost structural integrity by delamination after the 7.62 projectile impact. By contrast, the composite with cross-laid guaruman fibers kept its integrity for subsequent shootings as recommended by the standard. The single-target tests indicated a relatively higher limit velocity for .22 caliber projectile perforation, 255 m/s, and absorbed energy of 106 J for the cross-laid guaruman fibers, which are superior to corresponding results for other less known natural fiber epoxy composites.

scholarly journals Mechanical Characterization of Epoxy Filled with Seed Shells as Reinforcement

2019 ◽  
Vol 8 (4) ◽  
pp. 6972-6977
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Sodium Hydroxide ◽  
Natural Fiber ◽  
Fiber Composite ◽  
Flexural Modulus ◽  
Natural Fibers ◽  
Epoxy Composites ◽  
The Matrix ◽  
Sunflower Seed Shells

The use of natural fiber composite has been widely promoted in many industries such as construction, automotive and even aerospace. Natural fibers can be extracted from plants that are abundantly available in the form of waste such as sunflower seed shells (SSS) and groundnut shells (GNS). These fibers were chosen as the reinforcement in epoxy to form composites. The performance of composites was evaluated following the ASTM D3039 and ASTM D790 for tensile and flexural tests respectively. Eight types of composites were prepared using SSS and GNS fibers as reinforcement and epoxy as the matrix with the fiber content of 20wt %. The fibers were untreated and treated with Sodium Hydroxide (NaOH) at various concentrations (6%, 10%, 15%, and 20%) and soaking time (24, 48 and 72 hours). The treatment has successfully enhanced the mechanical properties of both composites, namely SSS/epoxy and GNS/epoxy composites. The SSS/epoxy composite has the best mechanical properties when the fibers were treated for 48 hours using 6% of NaOH that produced 22 MPa and 13 MPa of tensile and flexural strength respectively. Meanwhile, the treatment on groundnut shells with 10% sodium Hydroxide for 24 hours has increased the Flexural strength tremendously (53%), however no significant effect on the tensile strength. The same trend was also observed on the tensile and flexural modulus. The increase of 41% in flexural modulus after treatment with 10% NaOH for 24 hours was also the evidence of mechanical properties enhancement. The evidence of improved fiber and matrix bonding after fiber treatment was also observed using a scanning electron microscope (SEM). The SSS/epoxy composites performed better in tensile application, meanwhile the GNS/epoxy composites are good in flexural application.

scholarly journals Composites with Natural Fibers and Conventional Materials Applied in a Hard Armor: A Comparison

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1920 ◽  
Author(s):  
Fernanda Santos da Luz ◽  
Fabio da Costa Garcia Filho ◽  
Michelle Souza Oliveira ◽  
Lucio Fabio Cassiano Nascimento ◽  
Sergio Neves Monteiro
Keyword(s):  
Natural Fiber ◽  
Epoxy Composite ◽  
Natural Fibers ◽  
Ballistic Performance ◽  
Synthetic Fibers ◽  
Reinforced Polymer ◽  
Fiber Reinforced Polymer Composites ◽  
National Institute Of Justice ◽  
Additional Protection ◽  
Armor System

Natural-fiber-reinforced polymer composites have recently drawn attention as new materials for ballistic armor due to sustainability benefits and lower cost as compared to conventional synthetic fibers, such as aramid and ultra-high-molecular-weight polyethylene (UHMWPE). In the present work, a comparison was carried out between the ballistic performance of UHMWPE composite, commercially known as Dyneema, and epoxy composite reinforced with 30 vol % natural fibers extracted from pineapple leaves (PALF) in a hard armor system. This hard armor system aims to provide additional protection to conventional level IIIA ballistic armor vests, made with Kevlar, by introducing the PALF composite plate, effectively changing the ballistic armor into level III. This level of protection allows the ballistic armor to be safely subjected to higher impact projectiles, such as 7.62 mm caliber rifle ammunition. The results indicate that a hard armor with a ceramic front followed by the PALF/epoxy composite meets the National Institute of Justice (NIJ) international standard for level III protection and performs comparably to that of the Dyneema plate, commonly used in armor vests.

Compression molding of algae fiber and epoxy composites: Modeling of elastic modulus

2016 ◽  
Vol 37 (19) ◽  
pp. 1202-1216 ◽  
Author(s):  
Alejandra Constante ◽  
Selvum Pillay
Keyword(s):  
Fiber Volume Fraction ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Compaction Pressure ◽  
The United States ◽  
Fiber Composites ◽  
Epoxy Composites ◽  
Natural Fiber Composites ◽  
Fiber Volume

The demand for natural fiber composites in the automotive industry in both Europe and the United States has been forecasted to increase in the coming years. The natural fiber composites based on highly commercialized fibers such as flax, hemp, and sisal has grown to become an important sector of polymeric composites. However, little attention has been addressed to expanding natural fiber composites to include new sources of emerging natural reinforcements, such as reclaimed algae fibers, that have a multiple environmental benefits. Not only are extracted algae fibers biodegradable, the reclamation process has the added benefit of restoring health of waterways choked with algae. This study focuses on the processability of algae fiber–epoxy composites. Short fibers, chemically extracted from raw reclaimed algae, were prepared for natural fiber composite products in two ways. First, randomly oriented mats were produced using the wet-laid process to create layered, compression-molded laminates. Second, loose fibers were dispersed directly into the thermoset matrix to produce a bulk molding compound that was further compression molded into composite lamina. The effect of processing variables such as compaction pressure, temperature, and time were addressed. Moreover, the effect of fiber volume fraction ( υf) and fiber form were considered. Enhanced mechanical properties were found when 56% υf algae fiber was used for the compression-molded laminates composite. This variant exhibited an improvement on the flexural and tensile modulus of 70% and 86% when compared to the neat epoxy. However, the volume of porosity on the same variant was 11% due to lack of compression in some of the fibers. The effect of porosity on the theoretical stiffness was estimated by using the Cox–Krenchel model. Furthermore, an empirical exponential model was formulated to characterize the multi-scale effect of compaction pressure on the overall fiber volume fraction, υf.

scholarly journals Direct Comparison of the Structural Compression Characteristics of Natural and Synthetic Fiber-Epoxy Composites: Flax, Jute, Hemp, Glass and Carbon Fibers

Fibers ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 62
Author(s):  
Mike R. Bambach
Keyword(s):  
Glass Fiber ◽  
Natural Fiber ◽  
Fiber Composite ◽  
Natural Fibers ◽  
Fiber Composites ◽  
Epoxy Composites ◽  
Synthetic Fiber ◽  
Natural Fiber Composites ◽  
Composite Channels ◽  
Natural And Synthetic

Recent decades have seen substantial interest in the use of natural fibers in continuous fiber reinforced composites, such as flax, jute and hemp. Considering potential applications, it is of particular interest how natural fiber composites compare to synthetic fiber composites, such as glass and carbon, and if natural fibers can replace synthetic fibers in existing applications. Many studies have made direct comparisons between natural and synthetic fiber composites via material coupon testing; however, few studies have made such direct comparisons of full structural members. This study presents compression tests of geometrically identical structural channel sections fabricated from fiber-epoxy composites of flax, jute, hemp, glass and carbon. Glass fiber composites demonstrated superior tension material coupon properties to natural fiber composites. However, for the same fiber mass, structural compression properties of natural fiber composite channels were generally equivalent to, or in some cases superior to, glass fiber composite channels. This indicates there is substantial potential for natural fibers to replace glass fibers in structural compression members. Carbon fiber composites were far superior to all other composites, indicating little potential for replacement with natural fibers.

scholarly journals Study the Impact of Drilling Process Parameters on Natural Fiber Reinforced Herringbone Epoxy Composites

2020 ◽  
Vol 44 (5) ◽  
pp. 339-345
Author(s):  
Nagamadhu Mahadevappa ◽  
Vijay K. Shankar ◽  
Samuel Sehgal ◽  
Rajath Upadhya
Keyword(s):  
Regression Analysis ◽  
Process Parameters ◽  
Natural Fiber ◽  
Fiber Composite ◽  
Machining Process ◽  
Epoxy Composites ◽  
Drilling Process ◽  
Drilling Performance ◽  
Drill Diameter ◽  
The Impact

Common fiber composite overlays are attractive for a few applications, (for example, aviation and flying machine auxiliary parts) because of their predominant properties and bio-degradable. Typically, mechanical drilling process parameters are significant effect final machining process outcomes. It covers drilling performance like convectional drilling, grinding, vibration-influence twist drilling, and rapid boring, drilling apparatus geometry and materials, drilling actuated delamination and its smothering methodologies, thrust power, and wear rate. This paper aimed to address the effect and ranking of process parameters on trust force, torque, and delamination at both entry and exit of the hole sisal fabric herringbone reinforced epoxy composites. The herringbone woven sisal fabric reinforced epoxy composite is fabricated using conventional compression molding technique. The result shows that at higher speed and feed rate delamination at both entrance and exit, thrust force, and toque decreases. Optimum drill diameter found from 6 to 10 mm to obtain minimum responses. As four output parameters are deciding quality of drilled hole, further grey regression analysis is used to study the ranking of output responses. Form grey regression analysis it is found that for 2700 rpm spindle speed, 60 mm/min feed and 8 mm diameter exhibit minimum effort.

Mechanical Behaviour of Chemically Treated Reshira-Epoxy Composite at Cryogenic Temperatures

2012 ◽  
Vol 488-489 ◽  
pp. 718-723 ◽  
Author(s):  
M. Vasumathi ◽  
Murali Vela
Keyword(s):  
Room Temperature ◽  
Mechanical Performance ◽  
Natural Fiber ◽  
Epoxy Composite ◽  
Sodium Hydroxide Solution ◽  
Loss Modulus ◽  
Fiber Composite ◽  
Natural Fiber Composite ◽  
First Time ◽  
Cryogenic Conditions

Natural fiber composite has already proved its worth in various mechanical applications. Natural fibres with attractive properties such as low density, environment-friendliness and less processing work are widely available and provide an alternative to the conventional fibres. In this paper, the fibre reshira has been tried for the first time for cryogenic applications. Initially, the fibre is given chemical treatment with sodium hydroxide solution to enhance the adhesion between the fibre and the resin. The treated fibre is reinforced with epoxy resin and its properties such as storage modulus, loss modulus and Glass Transition Temperature are evaluated both at room temperature and under cryogenic conditions and these are compared to see which condition produces better mechanical performance.

Effect of Chemical Treatment on the Mechanical Properties of Luffa Fiber Reinforced Epoxy Composite

2020 ◽  
Vol 01 (02) ◽  
pp. 37-42 ◽  
Author(s):  
Dipto Chakrabarti ◽  
Md Shariful Islam ◽  
Kazi Jubair ◽  
Md Rashedul H Sarker
Keyword(s):  
Mechanical Properties ◽  
Chemical Treatment ◽  
Natural Fiber ◽  
Fiber Composite ◽  
Flexural Modulus ◽  
Tensile Modulus ◽  
Epoxy Composites ◽  
Fiber Reinforced ◽  
Before And After ◽  
Flexural Tests

Novel luffa fiber reinforced epoxy composites are prepared and their mechanical properties are investigated before and after chemical treatment. The unique natural knitting structure of luffa provides an excellent reinforcement to the epoxy matrix. Knowing that the fiber-matrix bond gets stronger and imparts more strength to the composite when chemical treatment is done on fibers, composites are manufactured by untreated and treated luffa fiber using epoxy as a matrix. Luffa fiber is treated using benzoyl chloride and NaOH. Tensile and flexural tests are conducted on composites to investigate the effect of chemical treatment. Test results have shown that the chemical treatment on fibers improved the tensile strength, tensile modulus, flexural strength and flexural modulus by 27.21%, 49.37%, 41.84% and 6.44% respectively. Tensile modulus of luffa fiber composite is found to be higher compared with commonly used natural fiber composites. The experimental investigation suggests that, chemically treated luffa fiber reinforced epoxy composites could be a potential lightweight material in various applications.

scholarly journals Interfacial Compatibility Evaluation on the Fiber Treatment in the Typha Fiber Reinforced Epoxy Composites and Their Effect on the Chemical and Mechanical Properties

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1316 ◽  
Author(s):  
Samsul Rizal ◽  
Ikramullah ◽  
Deepu Gopakumar ◽  
Sulaiman Thalib ◽  
Syifaul Huzni ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Natural Fiber ◽  
Epoxy Composite ◽  
Fiber Composite ◽  
Alkali Treatment ◽  
Epoxy Composites ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Interfacial Compatibility

Natural fiber composites have been widely used for various applications such as automotive components, aircraft components and sports equipment. Among the natural fibers Typha spp have gained considerable attention to replace synthetic fibers due to their unique nature. The untreated and alkali-treated fibers treated in different durations were dried under the sun for 4 h prior to the fabrication of Typha fiber reinforced epoxy composites. The chemical structure and crystallinity index of composites were examined via FT-IR and XRD respectively. The tensile, flexural and impact tests were conducted to investigate the effect of the alkali treated Typha fibers on the epoxy composite. From the microscopy analysis, it was observed that the fracture mechanism of the composite was due to the fiber and matrix debonding, fiber pull out from the matrix, and fiber damage. The tensile, flexural and impact strength of the Typha fiber reinforced epoxy composite were increased after 5% alkaline immersion compared to untreated Typha fiber composite. From these results, it can be concluded that the alkali treatment on Typha fiber could improve the interfacial compatibility between epoxy resin and Typha fiber, which resulted in the better mechanical properties and made the composite more hydrophobic. So far there is no comprehensive report about Typha fiber reinforcing epoxy composite, investigating the effect of the alkali treatment duration on the interfacial compatibility, and their effect on chemical and mechanical of Typha fiber reinforced composite, which plays a vital role to provide the overall mechanical performance to the composite.

A University Education

2017 ◽  
Author(s):  
David Willetts
Keyword(s):  
Higher Education ◽  
Modern Society ◽  
University Education ◽  
Modern World ◽  
Controversial Issues ◽  
The Us ◽  
The Individual ◽  
The University ◽  
First Time ◽  
The Relationship

Universities have a crucial role in the modern world. In England, entrance to universities is by nation-wide competition which means English universities have an exceptional influence on schools--a striking theme of the book. This important book first investigates the university as an institution and then tracks the individual on their journey to and through university. In A University Education, David Willetts presents a compelling case for the ongoing importance of the university, both as one of the great institutions of modern society and as a transformational experience for the individual. The book also makes illuminating comparisons with higher education in other countries, especially the US and Germany. Drawing on his experience as UK Minister for Universities and Science from 2010 to 2014, the author offers a powerful account of the value of higher education and the case for more expansion. He covers controversial issues in which he was involved from access for disadvantaged students to the introduction of L9,000 fees. The final section addresses some of the big questions for the future, such as the the relationship between universities and business, especially in promoting innovation.. He argues that the two great contemporary trends of globalisation and technological innovation will both change the university significantly. This is an authoritative account of English universities setting them for the first time in their new legal and regulatory framework.

scholarly journals Classic Prescription, Kai-Xin-San, Ameliorates Alzheimer’s Disease as an Effective Multitarget Treatment: From Neurotransmitter to Protein Signaling Pathway

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Sirui Guo ◽  
Jiahong Wang ◽  
Huarong Xu ◽  
Weiwei Rong ◽  
Cheng Gao ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Pc12 Cells ◽  
Protein Signaling ◽  
Pi3k Inhibitor Ly294002 ◽  
Single Target ◽  
Biological Methods ◽  
Cognition Impairment ◽  
First Time

Alzheimer’s disease (AD) is a widespread neurodegenerative disease caused by complicated disease-causing factors. Unsatisfactorily, curative effects of approved anti-AD drugs were not good enough due to their actions on single-target, which led to desperate requirements for more effective drug therapies involved in multiple pathomechanisms of AD. The anti-AD effect with multiple action targets of Kai-Xin-San (KXS), a classic prescription initially recorded in Bei Ji Qian Jin Yao Fang and applied in the treatment of dementia for thousands of years, was deciphered with modern biological methods in our study. Aβ25-35 and D-gal-induced AD rats and Aβ25-35-induced PC12 cells were applied to establish AD models. KXS could significantly improve cognition impairment by decreasing neurotransmitter loss and enhancing the expression of PI3K/Akt. For the first time, KXS was confirmed to improve the expression of PI3K/Akt by neurotransmitter 5-HT. Thereinto, PI3K/Akt could further inhibit Tau hyperphosphorylation as well as the apoptosis induced by oxidative stress and neuroinflammation. Moreover, all above-mentioned effects were verified and blocked by PI3K inhibitor, LY294002, in Aβ25-35-induced PC12 cells, suggesting the precise regulative role of KXS in the PI3K/Akt pathway. The utilization and mechanism elaboration of KXS have been proposed and dissected in the combination of animal, molecular, and protein strategies. Our results demonstrated that KXS could ameliorate AD by regulating neurotransmitter and PI3K/Akt signal pathway as an effective multitarget treatment so that the potential value of this classic prescription could be explored from a novel perspective.

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