Improved adhesion performances of aramid fibers with vinyl epoxy via supercritical carbon dioxide modification

NASA Astrophysics Data System (ADS)

Qin, M. L.; Kong, H. J.; Yu, M. H.; Teng, C. Q.

2017-06-01

In this paper, aramid fibers were treated under supercritical carbon dioxide (SCCO2) with isocyanate terminated liquid nitrile rubber to improve the adhesion performances of vinyl epoxy composites. The interfacial shear strength (IFSS) of vinyl epoxy composites was investigated by micro-bond test. The results indicate that the surface modification of aramid fibers in SCCO2 was an efficient method to increase the adhesion performances between fibers and vinyl epoxy. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were adopted to investigate the surface structure and composition of aramid fibers. The flexural strength and interlaminar shear strength (ILSS) of treated aramid fibers/vinyl epoxy composites was improved by 18.1% and 28.9% compared with untreated aramid fibers, respectively. Furthermore, the fractured surfaces of the composites were observed by SEM, which showed that the interfacial adhesion of composites has been remarkably changed.

Fused Deposition Technique for Continuous Fiber Reinforced Thermoplastic

NASA Astrophysics Data System (ADS)

Bettini, Paolo; Alitta, Gianluca; Sala, Giuseppe; Di Landro, Luca

2017-02-01

A simple technique for the production of continuous fiber reinforced thermoplastic by fused deposition modeling, which involves a common 3D printer with quite limited modifications, is presented. An adequate setting of processing parameters and deposition path allows to obtain components with well-enhanced mechanical characteristics compared to conventional 3D printed items. The most relevant problems related to the simultaneous feeding of fibers and polymer are discussed. The properties of obtained aramid fiber reinforced polylactic acid (PLA) in terms of impregnation quality and of mechanical response are measured.

Quantitative radiographic analysis of fiber reinforced polymer composites.

PubMed

Baidya, K P; Ramakrishna, S; Rahman, M; Ritchie, A

2001-01-01

X-ray radiographic examination of the bone fracture healing process is a widely used method in the treatment and management of patients. Medical devices made of metallic alloys reportedly produce considerable artifacts that make the interpretation of radiographs difficult. Fiber reinforced polymer composite materials have been proposed to replace metallic alloys in certain medical devices because of their radiolucency, light weight, and tailorable mechanical properties. The primary objective of this paper is to provide a comparable radiographic analysis of different fiber reinforced polymer composites that are considered suitable for biomedical applications. Composite materials investigated consist of glass, aramid (Kevlar-29), and carbon reinforcement fibers, and epoxy and polyether-ether-ketone (PEEK) matrices. The total mass attenuation coefficient of each material was measured using clinical X-rays (50 kev). The carbon fiber reinforced composites were found to be more radiolucent than the glass and kevlar fiber reinforced composites.

A Ballistic Material Model for Cross-Plied Unidirectional Ultra-High Molecular-Weight Polyethylene Fiber-Reinforced Armor-Grade Composites

DTIC Science & Technology

2008-01-01

strength polymeric fibers such as aramid (e.g. Kevlar ®, Twaron®, etc.) or oriented polyethy- lene fibers (e.g. Spectra®, Dyneema®, etc.) with an... phenolic -poly-vinyl-butyral resin and on 0◦/90◦ cross- plied oriented polyethylene fiber-reinforced vinyl-ester resin are widely used in hard personnel...are: (a) poly-aramids (e.g. Kevlar ®, Twaron®, Technora®); (b) highly oriented ultra-highmolecular-weight polyethylene, UHMWPE (e.g. Spectra®, Dyneema

Isolation of Aramid Nanofibers for High Strength and Toughness Polymer Nanocomposites.

PubMed

Lin, Jiajun; Bang, Sun Hwi; Malakooti, Mohammad H; Sodano, Henry A

2017-03-29

The development of nanoscale reinforcements that can be used to improve the mechanical properties of a polymer remains a challenge due to the long-standing difficulties with exfoliation and dispersion of existing materials. The dissimilar chemical nature of common nanofillers (e.g., carbon nanotubes, graphene) and polymeric matrix materials is the main reason for imperfect filler dispersion and, consequently, low mechanical performance of their composites relative to theoretical predictions. Here, aramid nanofibers that are intrinsically dispersible in many polymers are prepared from commercial aramid fibers (Kevlar) and isolated through a simple, scalable, and low-cost controlled dissolution method. Integration of the aramid nanofibers in an epoxy resin results in nanocomposites with simultaneously improved elastic modulus, strength, and fracture toughness. The improvement of these two mutually exclusive properties of nanocomposites is comparable to the enhancement of widely reported carbon nanotube reinforced nanocomposites but with a cost-effective and more feasible method to achieve uniform and stable dispersion. The results indicate the potential for aramid nanofibers as a new class of reinforcements for polymers.

Highly improved Uv resistance and composite interfacial properties of aramid fiber via iron (III) coordination

NASA Astrophysics Data System (ADS)

Cheng, Zheng; Hong, Dawei; Dai, Yu; Jiang, Chan; Meng, Chenbo; Luo, Longbo; Liu, Xiangyang

2018-03-01

The poor Uv stability and weak interfacial adhesion are considered as the bottleneck problems for further application of aramid fiber. Herein, a new strategy, Fe3+ coordination, was reported for aramid fiber to simultaneous improve its Uv resistance and composite interfacial shear strength. Fe3+ was introduced onto aramid fiber by coordinating with benzimidazole unit of fiber structure. It can reach a doping capacity of as high as 1516ug/g fiber, and the fiber surface is saturatedly covered with Fe3+. The chemical structure of Fe3+-benzimidazole brings about strong metal-enhanced fluorescence emission effect, which, in turn, greatly raises its Uv stability. Owing to the Fe3+ coordination, the tensile strength of Fe-coordinated fiber could preserve as high as 96% after Uv irradiation, compared with 73% of untreated fiber. Meanwhile, the introduction of Fe3+ improves the surface polarity of aramid fiber and consequently leads to the increase of the composite interfacial shear strength by 39%. It is believed that the Fe-coordinated fiber integrates the advantages of easy production, cost-effective and increased Uv stability, as well as high composite interfacial adhesion, and can be used as promising enhancement for the advanced composite material in harsh environment.

[The behavior of fiber-reinforced plastics during laser cutting].

PubMed

Emmrich, M; Levsen, K; Trasser, F J

1992-06-01

The pattern of the organic emissions, which are produced by processing of fibre reinforced plastics (epoxy resins reinforced by aramid and glass fibres and phenol resins reinforced by aramid fibre) with laser beam was studied and the concentrations of the main components determined. Despite the application of plastic materials with different chemical structures, the observed patterns are very similar. Mainly aromatic hydrocarbons are emitted, especially benzene and toluene, as well as some heteroatom-containing aromatic hydrocarbons (e.g. phenol). By use of oxygen as process gas the emissions during cutting of glass fibre reinforced plastics can be reduced, while they will be constantly high with aramid fibre reinforced plastics.

Mallow Fiber-Reinforced Epoxy Composites in Multilayered Armor for Personal Ballistic Protection

NASA Astrophysics Data System (ADS)

Nascimento, Lucio Fábio Cassiano; Louro, Luis Henrique Leme; Monteiro, Sergio Neves; Lima, Édio Pereira; da Luz, Fernanda Santos

2017-10-01

Lighter and less expensive polymer composites reinforced with natural fibers have been investigated as possible components of a multilayered armor system (MAS) for personal protection against high-velocity ammunition. Their ballistic performance was consistently found comparable with that of conventional Kevlar® synthetic aramid fiber. Among the numerous existing natural fibers with the potential for reinforcing polymer composites to replace Kevlar® in MAS, mallow fiber has not been fully investigated. Thus, the objective of this work is to evaluate the ballistic performance of epoxy composites reinforced with 30 vol.% of aligned mallow fibers as a second MAS layer backing a front ceramic plate. The results using high-velocity 7.62 ammunition show a similar indentation to a Kevlar® layer with the same thickness. An impedance matching calculation supports the similar ballistic performance of mallow fiber composite and Kevlar®. Reduced MAS costs associated with the mallow fiber composite are practical advantages over Kevlar®.

Investigation of mechanical properties of hemp/glass fiber reinforced nano clay hybrid composites

NASA Astrophysics Data System (ADS)

Unki, Hanamantappa Ningappa; Shivanand, H. K.; Vidyasagar, H. N.

2018-04-01

Over the last twenty to thirty years composite materials have been used in engineering field. Composite materials possess high strength, high strength to weight ratio due to these facts composite materials are becoming popular among researchers and scientists. The major proportion of engineering materials consists of composite materials. Composite materials are used in vast applications ranging from day-to-day household articles to highly sophisticated applications. In this paper an attempt is made to prepare three different composite materials using e-glass and Hemp. In this present investigation hybrid composite of Hemp, Glass fiber and Nano clay will be prepared by Hand-layup technique. The glass fiber used in this present investigation is E-glass fiber bi-directional: 90˚ orientation. The composite samples will be made in the form of a Laminates. The wt% of nanoclay added in the preparation of sample is 20 gm constant. The fabricated composite Laminate will be cut into corresponding profiles as per ASTM standards for Mechanical Testing. The effect of addition of Nano clay and variation of Hemp/glass fibers will be studied. In the present work, a new Hybrid composite is developed in which Hemp, E glass fibers is reinforced with epoxy resin and with Nano clay.

Wettability of nano-epoxies to UHMWPE fibers.

PubMed

Neema, S; Salehi-Khojin, A; Zhamu, A; Zhong, W H; Jana, S; Gan, Y X

2006-07-01

Ultra high molecular weight polyethylene (UHMWPE) fibers have a unique combination of outstanding mechanical, physical, and chemical properties. However, as reinforcements for manufacturing high performance composite materials, UHMWPE fibers have poor wettability with most polymers. As a result, the interfacial bonding strength between the fibers and polymer matrices is very low. Recently, developing so-called nano-matrices containing reactive graphitic nanofibers (r-GNFs) has been proposed to promote the wetting of such matrices to certain types of fiber reinforcements. In this work, the wettability of UHMWPE fibers with different epoxy matrices including a nano-epoxy, and a pure epoxy was investigated. Systematic experimental work was conducted to determine the viscosity of the epoxies, the contact angle between the epoxies and the fibers. Also obtained are the surface energy of the fibers and the epoxies. The experimental results show that the wettability of the UHMWPE fibers with the nano-epoxy is much better than that of the UHMWPE fibers with the pure epoxy.

The effect of fiber reinforcement type and water storage on strength properties of a provisional fixed partial denture resin.

PubMed

Uzun, Gülay; Keyf, Filiz

2003-04-01

Fracture resistance of provisional restorations is an important clinical concern. This property is directly related to transverse strength. Strengthening of provisional fixed partial dentures may result from reinforcement with various fiber types. This study evaluated the effect of fiber type and water storage on the transverse strength of a commercially available provisional resin under two different conditions. The denture resin was reinforced with either glass or aramid fiber or no reinforcement was used. Uniform samples were made from a commercially available autopolymerizing provisional fixed partial denture resin. Sixteen bar-shaped specimens (60 x 10 x 4 mm) were reinforced with pre-treated epoxy resin-coated glass fibers, with aramid fibers, or with no fibers. Eight specimens of each group, with and without fibers, were tested after 24 h of fabrication (immediate group), and after 30-day water storage. A three-point loading test was used to measure the transverse strength, the maximal deflection, and the modulus of elasticity. The Kruskal-Wallis Analysis of Variance was used to examine differences among the three groups, and then the Mann-Whitney U Test and Wilcoxon Signed Ranks Test were applied to determine pair-wise differences. The transverse strength and the maximal deflection values in the immediate group and in the 30-day water storage group were not statistically significant. In the group tested immediately, the elasticity modulus was found to be significant (P = 0.042). In the 30-day water storage group, all the values were statistically insignificant. The highest transverse strength was displayed by the glass-reinforced resin (66.25MPa) in the immediate group. The transverse strength value was 62.04MPa for the unreinforced samples in the immediate group. All the specimens exhibited lower transverse strength with an increase in water immersion time. The transverse strength value was 61.13 MPa for the glass-reinforced resin and was 61.24 MPa for the

Effects of postcuring on mechanical properties of pultruded fiber-reinforced epoxy composites and the neat resin

NASA Technical Reports Server (NTRS)

Long, Edward R., Jr.; Long, Sheila Ann T.; Funk, Joan G.; Collins, William D.; Gray, Stephanie L.

1989-01-01

The effects of postcuring on mechanical properties of pultruded fiber-reinforced epoxy-resin composites have been investigated. Composites with carbon, glass, and aramid reinforcement fibers were individually studied. The epoxy was a commercially-available resin that was especially developed for pultrusion fabrication. The pultrusions were conducted at 400 F with postcures at 400, 450, 500, and 550 F. Measurements of the flexural, shear, and interlaminar fracture-toughness properties showed that significant postcuring can occur during the pultrusion process. All three mechanical properties were degraded by the higher (500 and 550 F) temperatures; photomicrographs suggest that the degradation was caused at the fiber-resin interface for all three fiber types.

A mock heart engineered with helical aramid fibers for in vitro cardiovascular device testing.

PubMed

Jansen-Park, So-Hyun; Hsu, Po-Lin; Müller, Indra; Steinseifer, Ulrich; Abel, Dirk; Autschbach, Rüdiger; Rossaint, Rolf; Schmitz-Rode, Thomas

2017-04-01

Mock heart circulation loops (MHCLs) serve as in-vitro platforms to investigate the physiological interaction between circulatory systems and cardiovascular devices. A mock heart (MH) engineered with silicone walls and helical aramid fibers, to mimic the complex contraction of a natural heart, has been developed to advance the MHCL previously developed in our group. A mock aorta with an anatomical shape enables the evaluation of a cannulation method for ventricular assist devices (VADs) and investigation of the usage of clinical measurement systems like pressure-volume catheters. Ventricle and aorta molds were produced based on MRI data and cast with silicone. Aramid fibers were layered in the silicone ventricle to reproduce ventricle torsion. A rotating hollow shaft was connected to the apex enabling the rotation of the MH and the connection of a VAD. Silicone wall thickness, aramid fiber angle and fiber pitch were varied to generate different MH models. All MH models were placed in a tank filled with variable amounts of water and air simulating the compliance. In this work, physiological ventricular torsion angles (15°-26°) and physiological pressure-volume loops were achieved. This MHCL can serve as a comprehensive testing platform for cardiovascular devices, such as artificial heart valves and cannulation of VADs.

Structural Behavior of Concrete Beams Reinforced with Basalt Fiber Reinforced Polymer (BFRP) Bars

NASA Astrophysics Data System (ADS)

Ovitigala, Thilan

The main challenge for civil engineers is to provide sustainable, environmentally friendly and financially feasible structures to the society. Finding new materials such as fiber reinforced polymer (FRP) material that can fulfill the above requirements is a must. FRP material was expensive and it was limited to niche markets such as space shuttles and air industry in the 1960s. Over the time, it became cheaper and spread to other industries such as sporting goods in the 1980-1990, and then towards the infrastructure industry. Design and construction guidelines are available for carbon fiber reinforced polymer (CFRP), aramid fiber reinforced polymer (AFRP) and glass fiber reinforced polymer (GFRP) and they are currently used in structural applications. Since FRP is linear elastic brittle material, design guidelines for the steel reinforcement are not valid for FRP materials. Corrosion of steel reinforcement affects the durability of the concrete structures. FRP reinforcement is identified as an alternative to steel reinforcement in corrosive environments. Although basalt fiber reinforced polymer (BFRP) has many advantages over other FRP materials, but limited studies have been done. These studies didn't include larger BFRP bar diameters that are mostly used in practice. Therefore, larger beam sizes with larger BFRP reinforcement bar diameters are needed to investigate the flexural and shear behavior of BFRP reinforced concrete beams. Also, shear behavior of BFRP reinforced concrete beams was not yet studied. Experimental testing of mechanical properties and bond strength of BFRP bars and flexural and shear behavior of BFRP reinforced concrete beams are needed to include BFRP reinforcement bars in the design codes. This study mainly focuses on the use of BFRP bars as internal reinforcement. The test results of the mechanical properties of BFRP reinforcement bars, the bond strength of BFRP reinforcement bars, and the flexural and shear behavior of concrete beams

Lightweight Forms for Epoxy/Aramid Ducts

NASA Technical Reports Server (NTRS)

Mix, E. W.; Anderson, A. N.; Bedford, Donald L., Sr.

1986-01-01

Aluminum mandrels easy to remove. Lightweight aluminum mandrel for shaping epoxy/aramid ducts simplifies and speeds production. In new process, glass-reinforced epoxy/aramid cloth wrapped on aluminum mandrel. Stainless-steel flanges and other hardware fitted on duct and held by simple tooling. Entire assembly placed in oven to cure epoxy. After curing, assembly placed in alkaline bath dissolves aluminum mandrel in about 4 hours. Epoxy/aramid shell ready for use as duct. Aluminum mandrel used to make ducts of various inside diameters up to 6 in. Standard aluminum forms used. Conventional tube-bending equipment produces requisite curves in mandrels.

Statistical and Detailed Analysis on Fiber Reinforced Self-Compacting Concrete Containing Admixtures- A State of Art of Review

NASA Astrophysics Data System (ADS)

Athiyamaan, V.; Mohan Ganesh, G.

2017-11-01

Self-Compacting Concrete is one of the special concretes that have ability to flow and consolidate on its own weight, completely fill the formwork even in the presence of dense reinforcement; whilst maintaining its homogeneity throughout the formwork without any requirement for vibration. Researchers all over the world are developing high performance concrete by adding various Fibers, admixtures in different proportions. Various different kinds Fibers like glass, steel, carbon, Poly propylene and aramid Fibers provide improvement in concrete properties like tensile strength, fatigue characteristic, durability, shrinkage, impact, erosion resistance and serviceability of concrete[6]. It includes fundamental study on fiber reinforced self-compacting concrete with admixtures; its rheological properties, mechanical properties and overview study on design methodology statistical approaches regarding optimizing the concrete performances. The study has been classified into seven basic chapters: introduction, phenomenal study on material properties review on self-compacting concrete, overview on fiber reinforced self-compacting concrete containing admixtures, review on design and analysis of experiment; a statistical approach, summary of existing works on FRSCC and statistical modeling, literature review and, conclusion. It is so eminent to know the resent studies that had been done on polymer based binder materials (fly ash, metakaolin, GGBS, etc.), fiber reinforced concrete and SCC; to do an effective research on fiber reinforced self-compacting concrete containing admixtures. The key aim of the study is to sort-out the research gap and to gain a complete knowledge on polymer based Self compacting fiber reinforced concrete.

Studies on Effective Elastic Properties of CNT/Nano-Clay Reinforced Polymer Hybrid Composite

NASA Astrophysics Data System (ADS)

Thakur, Arvind Kumar; Kumar, Puneet; Srinivas, J.

2016-02-01

This paper presents a computational approach to predict elastic propertiesof hybrid nanocomposite material prepared by adding nano-clayplatelets to conventional CNT-reinforced epoxy system. In comparison to polymers alone/single-fiber reinforced polymers, if an additional fiber is added to the composite structure, it was found a drastic improvement in resultant properties. In this regard, effective elastic moduli of a hybrid nano composite are determined by using finite element (FE) model with square representative volume element (RVE). Continuum mechanics based homogenization of the nano-filler reinforced composite is considered for evaluating the volumetric average of the stresses and the strains under different periodic boundary conditions.A three phase Halpin-Tsai approach is selected to obtain the analytical result based on micromechanical modeling. The effect of the volume fractions of CNTs and nano-clay platelets on the mechanical behavior is studied. Two different RVEs of nano-clay platelets were used to investigate the influence of nano-filler geometry on composite properties. The combination of high aspect ratio of CNTs and larger surface area of clay platelets contribute to the stiffening effect of the hybrid samples. Results of analysis are validated with Halpin-Tsai empirical formulae.

Natural Mallow Fiber-Reinforced Epoxy Composite for Ballistic Armor Against Class III-A Ammunition

NASA Astrophysics Data System (ADS)

Nascimento, Lucio Fabio Cassiano; Holanda, Luane Isquerdo Ferreira; Louro, Luis Henrique Leme; Monteiro, Sergio Neves; Gomes, Alaelson Vieira; Lima, Édio Pereira

2017-10-01

Epoxy matrix composites reinforced with up to 30 vol pct of continuous and aligned natural mallow fibers were for the first time ballistic tested as personal armor against class III-A 9 mm FMJ ammunition. The ballistic efficiency of these composites was assessed by measuring the dissipated energy and residual velocity after the bullet perforation. The results were compared to those in similar tests of aramid fabric (Kevlar™) commonly used in vests for personal protections. Visual inspection and scanning electron microscopy analysis of impact-fractured samples revealed failure mechanisms associated with fiber pullout and rupture as well as epoxy cracking. As compared to Kevlar™, the mallow fiber composite displayed practically the same ballistic efficiency. However, there is a reduction in both weight and cost, which makes the mallow fiber composites a promising material for personal ballistic protection.

Pulmonary response to inhaled Kevlar aramid synthetic fibers in rats.

PubMed

Lee, K P; Kelly, D P; Kennedy, G L

1983-11-01

Groups of male rats were exposed to specially prepared ultrafine Kevlar pulp fibers (du Pont's registered trademark for certain aramid fibers) at atmospheric concentrations of either 0.1, 0.5, 3.0, or 18 mg/m3 for 2 weeks. Rats were killed at 0 and 2 weeks and 3 and 6 months postexposure (PE) except the rats exposed to 18 mg/m3, which were killed 0, 4, and 14 days and 1, 3, and 6 months PE. Another group of male rats was exposed to 18 mg/m3 (respirable dust approximately 2.5 mg/m3) of commercial Kevlar fibers for 2 weeks and were killed at 0 and 2 weeks and 3 and 6 months PE. Inhaled ultrafine Kevlar fibers were mostly phagocytized by alveolar macrophages (dust cells) in the alveolar ducts and adjoining alveoli after exposure to either 0.1 or 0.5 micrograms/m3. Most dust cells had disappeared and lungs showed a normal appearance throughout 6 months PE. The pulmonary response almost satisfied the biological criteria for a nuisance dust. Rats exposed to 3 mg/m3 ultrafine Kevlar fibers revealed occasional patchy thickening of alveolar ducts with dust cells and inflammatory cells but with no collagen fibers deposited throughout 6 months PE. After exposure to 18 mg/m3 ultrafine Kevlar, the respiratory bronchioles, alveolar ducts, and adjoining alveoli showed granulomatous lesions with dust cells by 2 weeks PE. The granulomatous lesions converted to patchy fibrotic thickening with dust cells after 1 month PE. The fibrotic lesions were markedly reduced in cellularity, size, and numbers from 3 to 6 months PE but revealed networks of reticulum fibers with slight collagen fiber deposition.

Surface modification of aramid fibers by bio-inspired poly(dopamine) and epoxy functionalized silane grafting.

PubMed

Sa, Rina; Yan, Yan; Wei, Zhenhai; Zhang, Liqun; Wang, Wencai; Tian, Ming

2014-12-10

A novel biomimetic surface modification method for meta-aramid (MPIA) fibers and the improvement on adhesion with rubber matrix was demonstrated. Inspired by the composition of adhesive proteins in mussels, we used dopamine (DOPA) self-polymerization to form thin, surface-adherent poly(dopamine) (PDA) films onto the surface of MPIA fibers simply by immersing MPIA fibers in a dopamine solution at room temperature. An epoxy functionalized silane (KH560) grafting was then carried out on the surface of the poly(dopamine)-coated MPIA, either by a "one-step" or "two-step" method, to introduce an epoxy group onto the MPIA fiber surface. The surface composition and microstructure of the modified MPIA was characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results indicated successful grafting of KH560 on the PDA-coated MPIA surface. A single-fiber pull-out test was applied to evaluate the adhesion of MPIA fibers with the rubber matrix. Compared with the untreated MPIA fibers, the adhesion strength between the modified MPIA fibers by "one step" method with rubber matrix has an increase of 62.5%.

Aligned Layers of Silver Nano-Fibers.

PubMed

Golovin, Andrii B; Stromer, Jeremy; Kreminska, Liubov

2012-02-01

We describe a new dichroic polarizers made by ordering silver nano-fibers to aligned layers. The aligned layers consist of nano-fibers and self-assembled molecular aggregates of lyotropic liquid crystals. Unidirectional alignment of the layers is achieved by means of mechanical shearing. Aligned layers of silver nano-fibers are partially transparent to a linearly polarized electromagnetic radiation. The unidirectional alignment and density of the silver nano-fibers determine degree of polarization of transmitted light. The aligned layers of silver nano-fibers might be used in optics, microwave applications, and organic electronics.

Influence of aramid fiber moisture regain during atmospheric plasma treatment on aging of treatment effects on surface wettability and bonding strength to epoxy

NASA Astrophysics Data System (ADS)

Ren, Yu; Wang, Chunxia; Qiu, Yiping

2007-09-01

One of the main differences between a low-pressure plasma treatment and an atmospheric pressure plasma treatment is that in atmosphere, the substrate material may absorb significant amount of water which may potentially influence the plasma treatment effects. This paper investigates how the moisture absorbed by aramid fibers during the atmospheric pressure plasma treatment influences the aging behavior of the modified surfaces. Kevlar 49 fibers with different moisture regains (MR) (0.5, 3.5 and 5.5%, respectively) are treated with atmospheric pressure plasma jet (APPJ) with helium as the carrier gas and oxygen as the treatment gas. Surface wettability and chemical compositions, and interfacial shear strengths (IFSS) to epoxy for the aramid fibers in all groups are determined using water contact angle measurements, X-ray photoelectron spectroscopy (XPS), and micro-bond pull out tests, respectively. Immediately after the plasma treatment, the treated fibers have substantially lower water contact angles, higher surface oxygen and nitrogen contents, and larger IFSS to epoxy than those of the control group. At the end of 30 day aging period, the fibers treated with 5.5% moisture regain had a lower water contact angle and more polar groups on the fiber surface, leading to 75% improvement of IFSS over the control fibers, while those for the 0.5 and 3.5% moisture regain groups were only 30%.

Fiber reinforced engineering plastics

Treesearch

Daniel F. Caulfield; Rodney E. Jacobson; Karl D. Sears; John H. Underwood

2001-01-01

Although natural fiber reinforced commodity thermoplastics have a wide range of nonstructural applications in the automotive and decking industries, there have been few reports of cellulosic fiber-reinforced engineering thermoplastics. The commonly held belief has been that the only thermoplastics amenable to natural-fibre reinforcement are limited to low-melting (...

Use of polypropylene fibers coated with nano-silica particles into a cementitious mortar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coppola, B., E-mail: bcoppola@unisa.it; Di Maio, L.; Scarfato, P.

Fiber reinforced cementitious composite (FRCC) materials have been widely used during last decades in order to overcome some of traditional cementitious materials issues: brittle behaviour, fire resistance, cover spalling, impact strength. For composite materials, fiber/matrix bond plays an important role because by increasing fiber/matrix interactions is possible to increase the behaviour of the entire material. In this study, in order to improve fiber to matrix adhesion, two chemical treatments of polypropylene fibers were investigated: alkaline hydrolysis and nano-silica sol-gel particles deposition. Treatmtents effect on fibers morphology and mechanical properties was investigated by scanning electron microscopy (SEM) and tensile tests. SEMmore » investigations report the presence of spherical nano-silica particles on fiber surface, in the case of sol-gel process, while alkaline hydrolysis leads to an increase of fibers roughness. Both treatments have negligible influence on fibers mechanical properties confirming the possibility of their use in a cementitious mortar. Pullout tests were carried out considering three embedded length of fibers in mortar samples (10, 20 and 30 mm, respectively) showing an increase of pullout energy for treated fibers. The influence on fiber reinforced mortar mechanical properties was investigated by three-point flexural tests on prismatic specimens considering two fibers length (15 and 30 mm) and two fibers volume fractions (0.50 and 1.00 %). A general increase of flexural strength over the reference mix was achieved and an overall better behaviour is recognizable for mortars containing treated fibers.« less

The effect of interlaminar graphene nano-sheets reinforced e-glass fiber/ epoxy on low velocity impact response of a composite plate

NASA Astrophysics Data System (ADS)

Al-Maharma, A. Y.; Sendur, P.

2018-05-01

In this study, we compare the inter-laminar effect of graphene nano-sheets (GNSs) and CNTs on the single and multiple dynamic impact response of E-glass fiber reinforced epoxy composite (GFEP). In the comparisons, raw GFEP composite is used as baseline for quantifying the improvement on the dynamic impact response. For that purpose, finite element based models are developed for GNSs on GFEP, graphene coating on glass fibers, inter-laminar composite of CNTs reinforced polyester at 7.5 vol%, and combinations of all these reinforcements. Comparisons are made on three metrics: (i) total deformation, (ii) the contact force, and (iii) internal energy of the composite plate. The improvement on axial modulus (E1) of GFEP reinforced with one layer of GNS (0.5 wt%) without polyester at lamination sequence of [0]8 is 29.4%, which is very close to the improvement of 31% on storage modulus for multi-layer graphene with 0.5 wt% reinforced E-glass/epoxy composite at room temperature. Using three GNSs (1.5 wt%) reinforced polyester composite as interlaminar layer results in an improvement of 57.1% on E1 of GFEP composite. The simulation results reveal that the interlaminar three GNSs/polyester composite at mid-plane of GFEP laminated composite can significantly improve the dynamic impact resistance of GFEP structure compared to the other aforementioned structural reinforcements. Reinforcing GFEP composite with three layers of GNSs/polyester composite at mid-plane results in an average of 35% improvement on the dynamic impact resistance for healthy and damaged composite plate under low velocity impacts of single and multiple steel projectiles. This model can find application in various areas including structural health monitoring, fire retardant composite, and manufacturing of high strength and lightweight mechanical parts such as gas tank, aircraft wings and wind turbine blades.

The usage of carbon fiber reinforcement polymer and glass fiber reinforcement polymer for retrofit technology building

NASA Astrophysics Data System (ADS)

Tarigan, Johannes; Meka, Randi; Nursyamsi

2018-03-01

Fiber Reinforcement Polymer has been used as a material technology since the 1970s in Europe. Fiber Reinforcement Polymer can reinforce the structure externally, and used in many types of buildings like beams, columns, and slabs. It has high tensile strength. Fiber Reinforcement Polymer also has high rigidity and strength. The profile of Fiber Reinforcement Polymer is thin and light, installation is simple to conduct. One of Fiber Reinforcement Polymer material is Carbon Fiber Reinforcement Polymer and Glass Fiber Reinforcement Polymer. These materials is tested when it is installed on concrete cylinders, to obtain the comparison of compressive strength CFRP and GFRP. The dimension of concrete is diameter of 15 cm and height of 30 cm. It is amounted to 15 and divided into three groups. The test is performed until it collapsed to obtain maximum load. The results of research using CFRP and GFRP have shown the significant enhancement in compressive strength. CFRP can increase the compressive strength of 26.89%, and GFRP of 14.89%. For the comparison of two materials, CFRP is more strengthening than GFRP regarding increasing compressive strength. The usage of CFRP and GFRP can increase the loading capacity.

Hybridized Thermoplastic Aramids: Enabling Material Technology For Future Force Headgear

DTIC Science & Technology

2006-11-01

keeping the complete helmet weight the same. Design Material Rolled steel Hadfield Steel Kevlar 29/PVB Phenolic Kevlar 129/PVB...Material Rolled steel Hadfield Steel Kevlar 29/PVB Phenolic Kevlar 129/PVB phenolic Thermoplastic aramid Twaron/PVB phenolic ...Deflection RESULTS Improved Fiber, Fiber Architecture, and Matrix Materials Enable Performance Enhancement PASGT: 19 Ply S735 Kevlar with PVB Phenolic

Leaf spring made of fiber-reinforced resin

NASA Technical Reports Server (NTRS)

Hori, J.

1986-01-01

A leaf spring made of a matrix reinforced by at least two types of reinforcing fibers with different Young's modulus is described in this Japanese patent. At least two layers of reinforcing fibers are formed by partially arranging the reinforcing fibers toward the direction of the thickness of the leaf spring. A mixture of different types of reinforced fibers is used at the area of boundary between the two layers of reinforced fibers. The ratio of blending of each type of reinforced fiber is frequently changed to eliminate the parts where discontinuous stress may be applied to the leaf spring. The objective of this invention is to prevent the rapid change in Young's modulus at the boundary area between each layer of reinforced fibers in the leaf spring.

Corrosion of steel members strengthenened with carbon fiber reinforced polymer sheets

NASA Astrophysics Data System (ADS)

Bumadian, Ibrahim

Due to many years of service at several cases of exposure at various environments there are many of steel bridges which are in need of rehabilitation. The infrastructure needs upgrading, repair or maintenance, and also strengthening, but by using an alternative as retrofits methods. The alternative retrofit method, which used fiber reinforced polymer (FRP) composite materials which their strength materials comes largely from the fiber such as carbon, glass, and aramid fiber. Of the most important materials used in the rehabilitation of infrastructure is a composite material newly developed in bonded externally carbon fiber and polymer (CFRP) sheets, which has achieved remarkable success in the rehabilitation and upgrading of structural members. This technique has many disadvantages one of them is galvanic corrosion. This study presents the effect of galvanic corrosion on the interfacial strength between carbon fiber reinforced polymer (CFRP) sheets and a steel substrate. A total of 35 double-lap joint specimens and 19 beams specimens are prepared and exposed to an aggressive service environment in conjunction with an electrical potential method accelerating corrosion damage. Six test categories are planned at a typical exposure interval of 12 hours, including five specimens per category for double-lap joint specimens. And six test categories are planned at a typical exposure interval of 12 hours, including three specimens per category for Beam section specimens. In addition one beam section specimen is control. The degree of corrosion is measured. Fourier transform infrared (FTIR) reflectance spectroscopy has been used to monitor and confirm the proposed corrosion mechanisms on the surface of CFRP. In this study we are using FTIR-spectroscopic measurement systems in the mid infrared (MIR) wavelength region (4000 - 400) cm-1 to monitor characteristic spectral features. Upon completion of corrosion processes, all specimens are monotonically loaded until failure

Physical and mechanical properties of PMMA bone cement reinforced with nano-sized titania fibers.

PubMed

Khaled, S M Z; Charpentier, Paul A; Rizkalla, Amin S

2011-02-01

X-ray contrast medium (BaSO(4) or ZrO(2)) used in commercially available PMMA bone cements imparts a detrimental effect on mechanical properties, particularly on flexural strength and fracture toughness. These lower properties facilitate the chance of implant loosening resulting from cement mantle failure. The present study was performed to examine the mechanical properties of a commercially available cement (CMW1) by introducing novel nanostructured titania fibers (n-TiO(2) fibers) into the cement matrix, with the fibers acting as a reinforcing phase. The hydrophilic nature of the n-TiO(2) fibers was modified by using a bifunctional monomer, methacrylic acid. The n-TiO(2) fiber content of the cement was varied from 0 to 2 wt%. Along with the mechanical properties (fracture toughness (K (IC)), flexural strength (FS), and flexural modulus (FM)) of the reinforced cements the following properties were investigated: complex viscosity-versus-time, maximum polymerization temperature (T (max)), dough time (t (dough)), setting time (t (set)), radiopacity, and in vitro biocompatibility. On the basis of the determined mechanical properties, the optimized composition was found at 1 wt% n-TiO(2) fibers, which provided a significant increase in K (IC) (63%), FS (20%), and FM (22%), while retaining the handling properties and in vitro biocompatibility compared to that exhibited by the control cement (CMW1). Moreover, compared to the control cement, there was no significant change in the radiopacity of any of the reinforced cements at p = 0.05. This study demonstrated a novel pathway to augment the mechanical properties of PMMA-based cement by providing an enhanced interfacial interaction and strong adhesion between the functionalized n-TiO( 2) fibers and PMMA matrix, which enhanced the effective load transfer within the cement.

Hybrid Fiber Layup and Fiber-Reinforced Polymeric Composites Produced Therefrom

NASA Technical Reports Server (NTRS)

Barnell, Thomas J. (Inventor); Garrigan, Sean P. (Inventor); Rauscher, Michael D. (Inventor); Dietsch, Benjamin A. (Inventor); Cupp, Gary N. (Inventor)

2018-01-01

Embodiments of a hybrid fiber layup used to form a fiber-reinforced polymeric composite, and a fiber-reinforced polymeric composite produced therefrom are disclosed. The hybrid fiber layup comprises one or more dry fiber strips and one or more prepreg fiber strips arranged side by side within each layer, wherein the prepreg fiber strips comprise fiber material impregnated with polymer resin and the dry fiber strips comprise fiber material without impregnated polymer resin.

Fabrication and characterization of differentiated aramid nanofibers and transparent films

NASA Astrophysics Data System (ADS)

Luo, Jingjing; Zhang, Meiyun; Yang, Bin; Liu, Guodong; Song, Shunxi

2018-03-01

Aramid nanofibers (ANFs) frequently are employed as versatile building blocks for constructing high-performance nanocomposites due to its structural and performance superiority. In this paper, the different ANFs and ANF films derived from the typical aramid yarns, chopped fiber, pulp fiber and fibrid fiber, respectively, were fabricated through deprotonation with potassium hydroxide in dimethyl sulphoxide, protonation with deionized water and vacuum-assisted filtration. The physical tests such as tensile test, ultraviolet transmittance and absorbance, thermogravimetric analysis were executed to evaluate and contrast the thermodynamic and optical performances of these differentiated ANFs and ANF films. The analytical results suggested that ANFs films prepared by the different forms of aramid macrofibers presented with differentiated properties such as mechanical behaviors, transparencies and flexibilities. And also it was found that the oversized nanofiber in length led to the formation of flocculation which was adverse for ANFs films in the formation of high strength. Whereas, small diameter just facilitated for the achievement of high stiffness and transparency. By contrast, the ANFs films made from chopped nanofiber, with aspect ratio of 200-500, exhibited good transparency, thermal stability and mechanical properties with transmittance value of 83%, TG10% around 521 °C, ultimate strength (σ) of 103.41 MPa, stiffness (E) of 4.70 GPa and strain at break of 5.56%. This work offers an alternative nanoscale building block as an effective nanofiller for preparing high-performance nanocomposites with different requirements in the potential fields such as transparent coating and flexible electrode or display materials, battery separator and microporous membrane.

Variabilities detected by acoustic emission from filament-wound Aramid fiber/epoxy composite pressure vessels

NASA Technical Reports Server (NTRS)

Hamstad, M. A.

1978-01-01

Two hundred and fifty Aramid fiber/epoxy pressure vessels were filament-wound over spherical aluminum mandrels under controlled conditions typical for advanced filament-winding. A random set of 30 vessels was proof-tested to 74% of the expected burst pressure; acoustic emission data were obtained during the proof test. A specially designed fixture was used to permit in situ calibration of the acoustic emission system for each vessel by the fracture of a 4-mm length of pencil lead (0.3 mm in diameter) which was in contact with the vessel. Acoustic emission signatures obtained during testing showed larger than expected variabilities in the mechanical damage done during the proof tests. To date, identification of the cause of these variabilities has not been determined.

Study on basalt fiber parameters affecting fiber-reinforced mortar

NASA Astrophysics Data System (ADS)

Orlov, A. A.; Chernykh, T. N.; Sashina, A. V.; Bogusevich, D. V.

2015-01-01

This article considers the effect of different dosages and diameters of basalt fibers on tensile strength increase during bending of fiberboard-reinforced mortar samples. The optimal dosages of fiber, providing maximum strength in bending are revealed. The durability of basalt fiber in an environment of cement, by means of microscopic analysis of samples of fibers and fiberboard-reinforced mortar long-term tests is examined. The article also compares the behavior of basalt fiber in the cement stone environment to a glass one and reveals that the basalt fiber is not subject to destruction.

Fiber reinforced cementitious matrix (FRCM) composites for reinforced concrete strengthening.

DOT National Transportation Integrated Search

2013-07-01

Fiber-reinforced composite systems are widely used for strengthening, repairing, and rehabilitation of reinforced concrete structural : members. A promising newly-developed type of composite, comprised of fibers and an inorganic cement-based matrix, ...

Fiber reinforced PMR polyimide composites

NASA Technical Reports Server (NTRS)

Cavano, P. J.; Winters, W. E.

1978-01-01

Commercially obtained PMR-15 polyimide prepregs with S-glass and graphite fiber reinforcements were evaluated along with in-house prepared glass and graphite cloth PMR 2 materials. A novel autoclave approach was conceived and used to demonstrate that both the PMR systems respond to 1.4 MPa (200 psi) autoclave pressures to produce void free composites equivalent to die molded laminates. Isothermal gravimetric analysis and subsequent mechanical property tests indicated that the PMR 2 system was significantly superior in thermo-oxidative stability, and that S-glass reinforcements may contribute to the accelerated degradation of composites at 316 C (600 F) when compared to graphite fiber reinforced composites. Fully reversed bending fatigue experiments were conducted with a type of fixture unused for organic matrix composites. These studies indicated that the graphite fiber composites were clearly superior in fatigue resistance to the glass fiber reinforced material and that PMR matrix composite systems yield performance of the same order as composite materials employing other families of matrices.

Flexural strength using Steel Plate, Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) on reinforced concrete beam in building technology

NASA Astrophysics Data System (ADS)

Tarigan, Johannes; Patra, Fadel Muhammad; Sitorus, Torang

2018-03-01

Reinforced concrete structures are very commonly used in buildings because they are cheaper than the steel structures. But in reality, many concrete structures are damaged, so there are several ways to overcome this problem, by providing reinforcement with Fiber Reinforced Polymer (FRP) and reinforcement with steel plates. Each type of reinforcements has its advantages and disadvantages. In this study, researchers discuss the comparison between flexural strength of reinforced concrete beam using steel plates and Fiber Reinforced Polymer (FRP). In this case, the researchers use Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) as external reinforcements. The dimension of the beams is 15 x 25 cm with the length of 320 cm. Based on the analytical results, the strength of the beam with CFRP is 1.991 times its initial, GFRP is 1.877 times while with the steel plate is 1.646 times. Based on test results, the strength of the beam with CFRP is 1.444 times its initial, GFRP is 1.333 times while the steel plate is 1.167 times. Based on these test results, the authors conclude that beam with CFRP is the best choice for external reinforcement in building technology than the others.

Effect of kenaf fiber in reinforced concrete slab

NASA Astrophysics Data System (ADS)

Syed Mohsin, S. M.; Baarimah, A. O.; Jokhio, G. A.

2018-04-01

The effect of kenaf fibers in reinforced concrete slab with different thickness is discusses and presented in this paper. Kenaf fiber is a type of natural fiber and is added in the reinforced concrete slab to improve the structure strength and ductility. For this study, three types of mixtures were prepared with fiber volume fraction of 0%, 1% and 2%, respectively. The design compressive strength considered was 20 MPa. Six cubes were prepared to be tested at 7th and 28th day. A total of six reinforced concrete slab with two variances of thickness were also prepared and tested under four-point bending test. The differences in the thickness is to study the potential of kenaf fiber to serve as part of shear reinforcement in reinforced concrete slab that was design to fail in shear. It was observed that, addition of kenaf fiber in reinforced concrete slab improves the flexural strength and ductility of the reinforced concrete slab. In the slab with reduction in thickness, the mode of failure change from brittle to ductile with the inclusion of kenaf fiber.

75 FR 34943 - Defense Federal Acquisition Regulation Supplement; Para-Aramid Fibers and Yarns Manufactured in a...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-21

... needed for national defense purposes. Another respondent notes that DuPont is in the process of building.... Domestic Para-Aramid Sewing Thread May Be of Lower Quality One respondent fully supported the interim rule... specification to use para-aramid thread that was heavier and weaker than the commercial thread that was used in...

Bond characteristics of steel fiber and deformed reinforcing steel bar embedded in steel fiber reinforced self-compacting concrete (SFRSCC)

NASA Astrophysics Data System (ADS)

Aslani, Farhad; Nejadi, Shami

2012-09-01

Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of the self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, ductility, toughness, energy absorption capacity, fracture toughness and cracking. Although the available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates the bond characteristics between steel fiber and SCC firstly. Based on the available experimental results, the current analytical steel fiber pullout model (Dubey 1999) is modified by considering the different SCC properties and different fiber types (smooth, hooked) and inclination. In order to take into account the effect of fiber inclination in the pullout model, apparent shear strengths ( τ ( app)) and slip coefficient ( β) are incorporated to express the variation of pullout peak load and the augmentation of peak slip as the inclined angle increases. These variables are expressed as functions of the inclined angle ( ϕ). Furthurmore, steel-concrete composite floors, reinforced concrete floors supported by columns or walls and floors on an elastic foundations belong to the category of structural elements in which the conventional steel reinforcement can be partially replaced by the use of steel fibers. When discussing deformation capacity of structural elements or civil engineering structures manufactured using SFRSCC, one must be able to describe thoroughly both the behavior of the concrete matrix reinforced with steel fibers and the interaction between this composite matrix and discrete steel reinforcement of the conventional type. However, even though the knowledge on bond behavior is essential for evaluating the overall behavior of structural components containing reinforcement and steel fibers

Fabrication of micro/nano optical fiber by mechano-electrospinning

NASA Astrophysics Data System (ADS)

Chen, Qinnan; Wu, Dezhi; Yu, Zhe; Mei, Xuecui; Fang, Ke; Sun, Daoheng

2017-10-01

We study a novel fabrication method of micro/nano optical fiber by mechano-electrospinning (MES) direct-written technology. MES process is able to precisely manipulate the position and diameter of the electro-spun micro/nano fiber by adjusting the mechanical drawing force, which through changing the speed of motion stage (substrate). By adjusting the substrate speed, the nozzle-to-substrate distance and the applied voltage, the poly(methyl methacrylate) (PMMA) micro/nano optical fibers (MNOF) with controlled diameter are obtained and the tapered MNOF are fabricated by continuously changing the substrate speed. The transmission characteristics of PMMA micro/nano fiber is experimentally demonstrated, and a PMMA micro/nano fiber based refractive index sensor is designed. Our works shows the new fabrication method of MNOF by MES has the potential in the field of light mode conversion, optical waveguide coupling, refractive index detection and new micro/nano optical fiber components.

Flexural toughness of steel fiber reinforced high performance concrete containing nano-SiO2 and fly ash.

PubMed

Zhang, Peng; Zhao, Ya-Nan; Li, Qing-Fu; Wang, Peng; Zhang, Tian-Hang

2014-01-01

This paper aims to clarify the effect of steel fiber on the flexural toughness of the high performance concrete containing fly ash and nano-SiO2. The flexural toughness was evaluated by two methods, which are based on ASTM C1018 and DBV-1998, respectively. By means of three-point bending method, the flexural toughness indices, variation coefficients of bearing capacity, deformation energy, and equivalent flexural strength of the specimen were measured, respectively, and the relational curves between the vertical load and the midspan deflection (P(V)-δ) were obtained. The results indicate that steel fiber has great effect on the flexural toughness parameters and relational curves (P(V)-δ) of the three-point bending beam specimen. When the content of steel fiber increases from 0.5% to 2%, the flexural toughness parameters increase gradually and the curves are becoming plumper and plumper with the increase of steel fiber content, respectively. However these flexural toughness parameters begin to decrease and the curves become thinner and thinner after the steel fiber content exceeds 2%. It seems that the contribution of steel fiber to the improvement of flexural toughness of the high performance concrete containing fly ash and nano-SiO2 is well performed only when the steel fiber content is less than 2%.

Mechanical Property Evaluation of Palm/Glass Sandwiched Fiber Reinforced Polymer Composite in Comparison with few natural composites

NASA Astrophysics Data System (ADS)

Raja Dhas, J. Edwin; Pradeep, P.

2017-10-01

Natural fibers available plenty can be used as reinforcements in development of eco friendly polymer composites. The less utilized palm leaf stalk fibers sandwiched with artificial glass fibers was researched in this work to have a better reinforcement in preparing a green composite. The commercially available polyester resin blend with coconut shell filler in nano form was used as matrix to sandwich these composites. Naturally available Fibers of palm leaf stalk, coconut leaf stalk, raffia and oil palm were extracted and treated with potassium permanganate solution which enhances the properties. For experimentation four different plates were fabricated using these fibers adopting hand lay-up method. These sandwiched composite plates are further machined to obtain ASTM standards Specimens which are mechanically tested as per standards. Experimental results reveal that the alkali treated palm leaf stalk fiber based polymer composite shows appreciable results than the others. Hence the developed composite can be recommended for fabrication of automobile parts.

Hybrid Effect Evaluation of Steel Fiber and Carbon Fiber on the Performance of the Fiber Reinforced Concrete

PubMed Central

Song, Weimin; Yin, Jian

2016-01-01

Fiber reinforcement is an important method to enhance the performance of concrete. In this study, the compressive test and impact test were conducted, and then the hybrid effect between steel fiber (SF) and carbon fiber (CF) was evaluated by employing the hybrid effect index. Compressive toughness and impact toughness of steel fiber reinforced concrete (SFRC), carbon fiber reinforced concrete (CFRC) and hybrid fiber reinforced concrete (HFRC) were explored at steel fiber volume fraction 0.5%, 1%, 1.5% and carbon fiber 0.1%, 0.2%, 0.3%. Results showed that the addition of steel fiber and carbon fiber can increase the compressive strength. SF, CF and the hybridization between them could increase the compressive toughness significantly. The impact test results showed that as the volume of fiber increased, the impact number of the first visible crack and the ultimate failure also increased. The improvement of toughness mainly lay in improving the crack resistance after the first crack. Based on the test results, the positive hybrid effect of steel fiber and carbon fiber existed in hybrid fiber reinforced concrete. The relationship between the compressive toughness and impact toughness was also explored. PMID:28773824

Hybrid Effect Evaluation of Steel Fiber and Carbon Fiber on the Performance of the Fiber Reinforced Concrete.

PubMed

Song, Weimin; Yin, Jian

2016-08-18

Fiber reinforcement is an important method to enhance the performance of concrete. In this study, the compressive test and impact test were conducted, and then the hybrid effect between steel fiber (SF) and carbon fiber (CF) was evaluated by employing the hybrid effect index. Compressive toughness and impact toughness of steel fiber reinforced concrete (SFRC), carbon fiber reinforced concrete (CFRC) and hybrid fiber reinforced concrete (HFRC) were explored at steel fiber volume fraction 0.5%, 1%, 1.5% and carbon fiber 0.1%, 0.2%, 0.3%. Results showed that the addition of steel fiber and carbon fiber can increase the compressive strength. SF, CF and the hybridization between them could increase the compressive toughness significantly. The impact test results showed that as the volume of fiber increased, the impact number of the first visible crack and the ultimate failure also increased. The improvement of toughness mainly lay in improving the crack resistance after the first crack. Based on the test results, the positive hybrid effect of steel fiber and carbon fiber existed in hybrid fiber reinforced concrete. The relationship between the compressive toughness and impact toughness was also explored.

Mechanical properties of woven glass fiber-reinforced composites.

PubMed

Kanie, Takahito; Arikawa, Hiroyuki; Fujii, Koichi; Ban, Seiji

2006-06-01

The aim of this investigation was to measure the flexural and compressive strengths and the corresponding moduli of cylindrical composite specimens reinforced with woven glass fiber. Test specimens were made by light-curing urethane dimethacrylate oligomer with woven glass fiber of 0.18-mm standard thickness. Tests were conducted using four reinforcement methods and two specimen diameters. Flexural strength and modulus of woven glass fiber-reinforced specimens were significantly greater than those without woven glass fiber (p < 0.01). Likewise, compressive strength of reinforced specimens was significantly greater than those without woven glass fiber (p < 0.01), except for specimens reinforced with woven glass fiber oriented at a tilt direction in the texture (p > 0.05). In terms of comparison between the two specimen diameters, no statistically significant differences in flexural strength and compressive strength (p > 0.05) were observed.

Ballistic Performance of Alimina/S-2 Glass-Reinforced Polymer-Matrix Composite Hybrid Lightweight Armor Against Armor Piercing (AP) and Non-AP Projectiles

DTIC Science & Technology

2007-01-01

and a phenolic -resin based polymeric matrix. Such armor panels offer superior protection against fragmented ballistic threats when compared to...database does not contain a material model for the HJ1 composite but provides a model for a Kevlar Fiber Reinforced Polymer (KFRP) containing 53 vol... phenolic resin and epoxy yield stresses and then with a ratio of the S-2 glass and aramid fibers volume fractions. To test the validity of the

Composite strengthening. [of nonferrous, fiber reinforced alloys

NASA Technical Reports Server (NTRS)

Stoloff, N. S.

1976-01-01

The mechanical behavior of unidirectionally reinforced metals is examined, with particular attention to fabrication techniques for artificial composites and eutectic alloys and to principles of fiber reinforcement. The properties of artificial composites are discussed in terms of strength of fiber composites, strength of ribbon-reinforced composites, crack initiation, crack propagation, and creep behavior. The properties of eutectic composites are examined relative to tensile strength, compressive strength, fracture, high-temperature strength, and fatigue. In the case of artificial composites, parallelism of fibers, good bonding between fibers and matrix, and freedom of fibers from damage are all necessary to ensure superior performance. For many eutectic systems there are stringent boundary conditions relative to melt purity and superheat, atmosphere control, temperature gradient, and growth rate in order to provide near-perfect alignment of the reinforcements with a minimum of growth defects.

Effects of Fiber Reinforcement on Clay Aerogel Composites

PubMed Central

Finlay, Katherine A.; Gawryla, Matthew D.; Schiraldi, David A.

2015-01-01

Novel, low density structures which combine biologically-based fibers with clay aerogels are produced in an environmentally benign manner using water as solvent, and no additional processing chemicals. Three different reinforcing fibers, silk, soy silk, and hemp, are evaluated in combination with poly(vinyl alcohol) matrix polymer combined with montmorillonite clay. The mechanical properties of the aerogels are demonstrated to increase with reinforcing fiber length, in each case limited by a critical fiber length, beyond which mechanical properties decline due to maldistribution of filler, and disruption of the aerogel structure. Rather than the classical model for reinforced composite properties, the chemical compatibility of reinforcing fibers with the polymer/clay matrix dominated mechanical performance, along with the tendencies of the fibers to kink under compression. PMID:28793515

Theory of fiber reinforced materials

NASA Technical Reports Server (NTRS)

Hashin, Z.

1972-01-01

A unified and rational treatment of the theory of fiber reinforced composite materials is presented. Fundamental geometric and elasticity considerations are throughly covered, and detailed derivations of the effective elastic moduli for these materials are presented. Biaxially reinforced materials which take the form of laminates are then discussed. Based on the fundamentals presented in the first portion of this volume, the theory of fiber-reinforced composite materials is extended to include viscoelastic and thermoelastic properties. Thermal and electrical conduction, electrostatics and magnetostatics behavior of these materials are discussed. Finally, a brief statement of the very difficult subject of physical strength is included.

Flexural Toughness of Steel Fiber Reinforced High Performance Concrete Containing Nano-SiO2 and Fly Ash

PubMed Central

Zhao, Ya-Nan; Li, Qing-Fu; Wang, Peng; Zhang, Tian-Hang

2014-01-01

This paper aims to clarify the effect of steel fiber on the flexural toughness of the high performance concrete containing fly ash and nano-SiO2. The flexural toughness was evaluated by two methods, which are based on ASTM C1018 and DBV-1998, respectively. By means of three-point bending method, the flexural toughness indices, variation coefficients of bearing capacity, deformation energy, and equivalent flexural strength of the specimen were measured, respectively, and the relational curves between the vertical load and the midspan deflection (P V-δ) were obtained. The results indicate that steel fiber has great effect on the flexural toughness parameters and relational curves (P V-δ) of the three-point bending beam specimen. When the content of steel fiber increases from 0.5% to 2%, the flexural toughness parameters increase gradually and the curves are becoming plumper and plumper with the increase of steel fiber content, respectively. However these flexural toughness parameters begin to decrease and the curves become thinner and thinner after the steel fiber content exceeds 2%. It seems that the contribution of steel fiber to the improvement of flexural toughness of the high performance concrete containing fly ash and nano-SiO2 is well performed only when the steel fiber content is less than 2%. PMID:24883395

Process of Making Boron-Fiber Reinforced Composite Tape

NASA Technical Reports Server (NTRS)

Belvin, Harry L. (Inventor); Cano, Roberto J. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

2002-01-01

The invention is an apparatus and method for producing a hybrid boron reinforced polymer matrix composition from powder pre-impregnated fiber tow bundles and a linear array of boron fibers. The boron fibers are applied onto the powder pre-impregnated fiber tow bundles and then are processed within a processing component having an impregnation bar assembly. After passing through variable-dimension forming nip-rollers, the powder pre-impregnated fiber tow bundles with the boron fibers become a hybrid boron reinforced polymer matrix composite tape. A driving mechanism pulls the powder pre-impregnated fiber tow bundles with boron fibers through the processing line of the apparatus and a take-up spool collects the formed hybrid boron-fiber reinforced polymer matrix composite tape.

Flexural strength of self compacting fiber reinforced concrete beams using polypropylene fiber: An experimental study

NASA Astrophysics Data System (ADS)

Lisantono, Ade; Praja, Baskoro Abdi; Hermawan, Billy Nouwen

2017-11-01

One of the methods to increase the tensile strength of concrete is adding a fiber material into the concrete. While to reduce a noise in a construction project, a self compacting concrete was a good choices in the project. This paper presents an experimental study of flexural behavior and strength of self compacting fiber reinforced concrete (RC) beams using polypropylene fiber. The micro monofilament polypropylene fibers with the proportion 0.9 kg/m3 of concrete weight were used in this study. Four beam specimens were cast and tested in this study. Two beams were cast of self compacting reinforced concrete without fiber, and two beams were cast of self compacting fiber reinforced concrete using polypropylene. The beams specimen had the section of (180×260) mm and the length was 2000 mm. The beams had simple supported with the span of 1800 mm. The longitudinal reinforcements were using diameter of 10 mm. Two reinforcements of Ø10 mm were put for compressive reinforcement and three reinforcements of Ø10 mm were put for tensile reinforcement. The shear reinforcement was using diameter of 8 mm. The shear reinforcements with spacing of 100 mm were put in the one fourth near to the support and the spacing of 150 mm were put in the middle span. Two points loading were used in the testing. The result shows that the load-carrying capacity of the self compacting reinforced concrete beam using polypropylene was a little bit higher than the self compacting reinforced concrete beam without polypropylene. The increment of load-carrying capacity of self compacting polypropylene fiber reinforced concrete was not so significant because the increment was only 2.80 % compare to self compacting non fiber reinforced concrete. And from the load-carrying capacity-deflection relationship curves show that both the self compacting polypropylene fiber reinforced concrete beam and the self compacting non fiber reinforced concrete beam were ductile beams.

A Study of Array Direction HDPE Fiber Reinforced Mortar

NASA Astrophysics Data System (ADS)

Kamsuwan, Trithos

2018-02-01

This paper presents the effect of array direction HDPE fiber using as the reinforced material in cement mortar. The experimental data were created reference to the efficiency of using HDPE fiber reinforced on the tensile properties of cement mortar with different high drawn ratio of HDPE fibers. The fiber with the different drawn ratio 25x (d25 with E xx), and 35x (d35 with E xx) fiber volume fraction (0%, 1.0%, 1.5%) and fiber length 20 mm. were used to compare between random direction and array direction of HDPE fibers and the stress - strain displacement relationship behavior of HDPE short fiber reinforced cement mortar were investigated. It was found that the array direction with HDPE fibers show more improved in tensile strength and toughness when reinforced in cement mortar.

Demonstration of an ultra-wideband optical fiber inline polarizer with metal nano-grid on the fiber tip.

PubMed

Lin, Yongbin; Guo, Junpeng; Lindquist, Robert G

2009-09-28

Dramatic increase in the bandwidth of optical fiber inline polarizer can be achieved by using metal nano-grid on the fiber tip. However, high extinction ratio of such fiber polarizer requires high spatial frequency metal nano girds with high aspect ratio on the small area of optical fiber tip. We report the development of a nano-fabrication process on the optical fiber tip, and the design and realization of the first ultra-wideband fiber inline polarization device with Au nano gird fabricated on a single mode optical fiber end face.

Anisotropic contraction of hydrogel reinforced by aligned fibers

NASA Astrophysics Data System (ADS)

Olvera de La Cruz, Monica; Liu, Shuangping

Hydrogel reinforced by aligned fibers can have strong anisotropic contraction or swelling behavior triggered by external stimuli, which has been largely employed in realizing soft actuators for artificial muscles as well as many biological systems. In this work, we investigate how this anisotropic behavior is controlled by the dimension of the embedded fibers and their reinforcement to the surrounding hydrogel. We describe the anisotropic contraction of hydrogels with rigid fibers using the Flory-Rehner thermodynamic model under periodic boundary conditions. It is found that a hydrogel reinforced by aligned fibers exhibits larger anisotropy when it is pre-stretched before contraction. Using finite element method, we further observe that the anisotropic contraction is dampened by reducing the fiber-fiber distance due to the finite size of the fibers.

Fiber-Reinforced Concrete For Hardened Shelter Construction

DTIC Science & Technology

1993-02-01

reduced cost and weight versus the symmetrically rebar reinforced beam design using normal-weight, standard-strength concrete currently used by the...while possibly reducing their cost and weight. Emphasis is placed on modular construction using prefabricated fiber- and rebar -reinforced concrete ...fiber- and rebar -reinforced concrete structural members into U.S. Air Force hardened structure designs. vii (The reverse of this page is blank) PREFACE

Reinforcing aluminum alloys with high strength fibers

NASA Technical Reports Server (NTRS)

Kolpashnikov, A. I.; Manuylov, V. F.; Chukhin, B. D.; Shiryayev, Y. V.; Shurygin, A. S.

1982-01-01

A study is made of the possibility of reinforcing aluminum and aluminum based alloys with fibers made of high strength steel wire. The method of introducing the fibers is described in detail. Additional strengthening by reinforcement of the high alloy system Al - An - Mg was investigated.

Self-healing in single and multiple fiber(s) reinforced polymer composites

NASA Astrophysics Data System (ADS)

Woldesenbet, E.

2010-06-01

You Polymer composites have been attractive medium to introduce the autonomic healing concept into modern day engineering materials. To date, there has been significant research in self-healing polymeric materials including several studies specifically in fiber reinforced polymers. Even though several methods have been suggested in autonomic healing materials, the concept of repair by bleeding of enclosed functional agents has garnered wide attention by the scientific community. A self-healing fiber reinforced polymer composite has been developed. Tensile tests are carried out on specimens that are fabricated by using the following components: hollow and solid glass fibers, healing agent, catalysts, multi-walled carbon nanotubes, and a polymer resin matrix. The test results have demonstrated that single fiber polymer composites and multiple fiber reinforced polymer matrix composites with healing agents and catalysts have provided 90.7% and 76.55% restoration of the original tensile strength, respectively. Incorporation of functionalized multi-walled carbon nanotubes in the healing medium of the single fiber polymer composite has provided additional efficiency. Healing is found to be localized, allowing multiple healing in the presence of several cracks.

Structural Foaming at the Nano-, Micro-, and Macro-Scales of Continuous Carbon Fiber Reinforced Polymer Matrix Composites

DTIC Science & Technology

2012-10-29

up to 40%. Approach: Our approach was to work with conventional composite systems manufactured through the traditional prepreg and autoclave...structural porosity at MNM scales could be introduced into the matrix, the carbon fiber reinforcement, and during prepreg lamination processing, without...areas, including fibers. Furthermore, investigate prepreg thickness and resin content effects on the thermomechanical performance of laminated

Carbon nano fibers reinforced composites origami inspired mechanical metamaterials with passive and active properties

NASA Astrophysics Data System (ADS)

Kshad, Mohamed Ali E.; D'Hondt, Clement; Naguib, Hani E.

2017-10-01

Core panels used for compression or impact damping are designed to dissipate energy and to reduce the transferred force and energy. They are designed to have high strain and deformation with low density. The geometrical configuration of such cores plays a significant role in redistributing the applied forces to dampen the compression and impact energy. Origami structures are renowned for affording large macroscopic deformation which can be employed for force redistribution and energy damping. The material selection for the fabrication of origami structures affects the core capacity to withstand compression and impact loads. Polymers are characterized by their high compression and impact resistance; the drawback of polymers is the low stiffness and elastic moduli compared with metallic materials. This work is focused on the study of the effect of Carbon Nano Fibers (CNF) on the global mechanical properties of the origami panel cores made of polymeric blends. The base matrix materials used were Polylactic Acid (PLA) and Thermoplastic Polyurethane (TPU) blends, and the percentages of the PLA/TPU were 100/0, 20/80, 65/35, 50/50, 20/80, and 0/100 as a percentage of weight. The weight percentages of CNF added to the polymeric blends were 1%, 3%, and 5%. This paper deals with the fabrication process of the polymeric reinforced blends and the origami cores, in order to predict the best fabrication conditions. The dynamic scanning calorimetry and the dynamic mechanical analyzer were used to test the reinforced blended base material for thermomechanical and viscoelastic properties. The origami core samples were fabricated using per-molded geometrical features and then tested for compression and impact properties. The results of the study were compared with previous published results which showed that there is considerable enhancement in the mechanical properties of the origami cores compared with the pure blended polymeric origami cores. The active properties of the origami

[Carbon fiber-reinforced plastics as implant materials].

PubMed

Bader, R; Steinhauser, E; Rechl, H; Siebels, W; Mittelmeier, W; Gradinger, R

2003-01-01

Carbon fiber-reinforced plastics have been used clinically as an implant material for different applications for over 20 years.A review of technical basics of the composite materials (carbon fibers and matrix systems), fields of application,advantages (e.g., postoperative visualization without distortion in computed and magnetic resonance tomography), and disadvantages with use as an implant material is given. The question of the biocompatibility of carbon fiber-reinforced plastics is discussed on the basis of experimental and clinical studies. Selected implant systems made of carbon composite materials for treatments in orthopedic surgery such as joint replacement, tumor surgery, and spinal operations are presented and assessed. Present applications for carbon fiber reinforced plastics are seen in the field of spinal surgery, both as cages for interbody fusion and vertebral body replacement.

Cytotoxicity of silica-glass fiber reinforced composites.

PubMed

Meriç, Gökçe; Dahl, Jon E; Ruyter, I Eystein

2008-09-01

Silica-glass fiber reinforced polymers can be used for many kinds of dental applications. The fiber reinforcement enhances the mechanical properties of the polymers, and they have good esthetic attributes. There is good initial bonding of glass fibers to polymers via an interface made from silane coupling agents. The aim of this in vitro study was to determine the cytotoxicity of two polymers reinforced with two differently sized silica-glass fibers before and after thermal cycling. Cytotoxicity of the polymers without fibers was also evaluated. Two different resin mixtures (A and B) were prepared from poly(vinyl chloridecovinylacetate) powder and poly(methyl methacrylate) (PMMA) dissolved in methyl methacrylate and mixed with different cross-linking agents. The resin A contained the cross-linking agents ethylene glycol dimethacrylate and 1,4-butanediol dimethacrylate, and for resin B diethylene glycol dimethacrylate was used. Woven silica-glass fibers were used for reinforcement. The fibers were sized with either linear poly(butyl methacrylate)-sizing or cross-linking PMMA-sizing. Cytotoxicity was evaluated by filter diffusion test (ISO 7405:1997) of newly made and thermocycled test specimens. Extracts were prepared according to ISO 10993-12 from newly made and from thermocycled specimens and tested by the MTT assay. The results from the experiments were statistically analyzed by one-way ANOVA and Tukey's test (rho<0.05). The filter diffusion test disclosed no change in staining intensity at the cell-test sample contact area indicating non-cytotoxicity in all experimental groups. Cell viability assessed by MTT assay was more than 90% in all experimental groups. All are non-cytotoxic. It can be concluded that correctly processed heat polymerized silica-glass fiber reinforced polymers induced no cytotoxicity and that thermocycling did not alter this property.

Effects of Constituents and Lay-up Configuration on Drop-Weight Tests of Fiber-Metal Laminates

NASA Astrophysics Data System (ADS)

Liu, Yanxiong; Liaw, Benjamin

2010-02-01

Impact responses and damage of various fiber-metal laminates were studied using a drop-weight instrument with the post-impact damage characteristics being evaluated through ultrasonic and mechanical sectioning techniques. The first severe failure induced by the low-velocity drop-weight impact occurred as delamination between the aluminum and fiber-epoxy layers at the non-impact side. It was followed by a visible shear crack in the outer aluminum layer on the non-impact face. Through-thickness shear cracks in the aluminum sheets and severe damage in the fiber laminated layers (including delamination between adjacent fiber-epoxy laminae with different fiber orientations) developed under higher energy impacts. The impact properties of fiber-metal laminates varied with different constituent materials and fiber orientations. Since it was punched through easily, the aramid-fiber reinforced fiber-metal laminates (ARALL) offered poorer impact resistance than the glass-fiber reinforced fiber-metal laminates (GLARE). Tougher and more ductile aluminum alloys improved the impact resistance. GLARE made of cross-ply prepregs provided better impact resistance than GLARE with unidirectional plies.

Fiber-reinforced scaffolds in soft tissue engineering

PubMed Central

Wang, Wei; Fan, Yubo; Wang, Xiumei; Watari, Fumio

2017-01-01

Abstract Soft tissue engineering has been developed as a new strategy for repairing damaged or diseased soft tissues and organs to overcome the limitations of current therapies. Since most of soft tissues in the human body are usually supported by collagen fibers to form a three-dimensional microstructure, fiber-reinforced scaffolds have the advantage to mimic the structure, mechanical and biological environment of natural soft tissues, which benefits for their regeneration and remodeling. This article reviews and discusses the latest research advances on design and manufacture of novel fiber-reinforced scaffolds for soft tissue repair and how fiber addition affects their structural characteristics, mechanical strength and biological activities in vitro and in vivo. In general, the concept of fiber-reinforced scaffolds with adjustable microstructures, mechanical properties and degradation rates can provide an effective platform and promising method for developing satisfactory biomechanically functional implantations for soft tissue engineering or regenerative medicine. PMID:28798872

Experimental research on continuous basalt fiber and basalt-fibers-reinforced polymers

NASA Astrophysics Data System (ADS)

Zhang, Xueyi; Zou, Guangping; Shen, Zhiqiang

2008-11-01

The interest for continuous basalt fibers and reinforced polymers has recently grown because of its low price and rich natural resource. Basalt fiber was one type of high performance inorganic fibers which were made from natural basalt by the method of melt extraction. This paper discusses basic mechanical properties of basalt fiber. The other work in this paper was to conduct tensile testing of continuous basalt fiber-reinforced polymer rod. Tensile strength and stress-strain curve were obtained in this testing. The strength of rod was fairly equal to rod of E-glass fibers and weaker than rod of carbon fibers. Surface of crack of rod was studied. An investigation of fracture mechanism between matrix and fiber was analyzed by SEM (Scanning electron microscopy) method. A poor adhesion between the matrix and fibers was also shown for composites analyzing SEM photos. The promising tensile properties of the presented basalt fibers composites have shown their great potential as alternative classical composites.

Specially Treated Aramid Fiber Stabilized Gel-Emulsions: Preparation of Porous Polymeric Monoliths and Highly Efficient Removing of Airborne HCHO.

PubMed

Liu, Jianfei; Chen, Xiangli; Wang, Pei; Fu, Xuwei; Liu, Kaiqiang; Fang, Yu

2017-08-01

Porous polymeric monoliths with densities as low as ≈0.060 g cm -3 are prepared in a gel-emulsion template way, of which the stabilizer employed is a newly discovered acidified aramid fiber that is so efficient that 0.05% (w/v, accounts for continuous phase) is enough to gel the system. The porous monoliths as obtained can be dried at ambient conditions, avoiding energy-consuming processes. Importantly, the monoliths show selective adsorption to HCHO, and the corresponding adsorption capacity (M6) is ≈2700 mg g -1 , the best result that is reported until now. More importantly, the monoliths can be reused after drying. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of fiber architecture on flexural characteristics and fracture of fiber-reinforced dental composites.

PubMed

Karbhari, Vistasp M; Strassler, Howard

2007-08-01

The aim of this study was to compare and elucidate the differences in damage mechanisms and response of fiber-reinforced dental resin composites based on three different brands under flexural loading. The types of reinforcement consisted of a unidirectional E-glass prepreg (Splint-It from Jeneric/Petron Inc.), an ultrahigh molecular weight polyethylene fiber based biaxial braid (Connect, Kerr) and an ultrahigh molecular weight polyethylene fiber based leno-weave (Ribbond). Three different commercially available fiber reinforcing systems were used to fabricate rectangular bars, with the fiber reinforcement close to the tensile face, which were tested in flexure with an emphasis on studying damage mechanisms and response. Eight specimens (n=8) of each type were tested. Overall energy capacity as well as flexural strength and modulus were determined and results compared in light of the different abilities of the architectures used. Under flexural loading unreinforced and unidirectional prepreg reinforced dental composites failed in a brittle fashion, whereas the braid and leno-weave reinforced materials underwent significant deformation without rupture. The braid reinforced specimens showed the highest peak load. The addition of the unidirectional to the matrix resulted in an average strain of 0.06mm/mm which is 50% greater than the capacity of the unreinforced matrix, whereas the addition of the braid and leno-weave resulted in increases of 119 and 126%, respectively, emphasizing the higher capacity of both the UHM polyethylene fibers and the architectures to hold together without rupture under flexural loading. The addition of the fiber reinforcement substantially increases the level of strain energy in the specimens with the maximum being attained in the braid reinforced specimens with a 433% increase in energy absorption capability above the unreinforced case. The minimum scatter and highest consistency in response is seen in the leno-weave reinforced specimens

Cyanate Ester Resin Modified with Nano-particles for Inclusion in Continuous Fiber Reinforced Composites

DTIC Science & Technology

2011-02-25

custom built rotating oven, to prevent settling during cure. The filler content in the test specimen are verified by thermogravimetric analysis (TGA...using a Shimadzu SA-CP3 centrifugal particle size analyzer. The moisture absorption of the nanoparticles was studied using a Q50 thermogravimetric ...low viscosity bisphenol E cyanate ester resin (BECy) resin reinforced with macro scale carbon fibers and negative CTE nanoparticles . Polymer

Self-patterning Gd nano-fibers in Mg-Gd alloys

DOE PAGES

Li, Yangxin; Wang, Jian; Chen, Kaiguo; ...

2016-12-07

Manipulating the shape and distribution of strengthening units, e.g. particles, fibers, and precipitates, in a bulk metal, has been a widely applied strategy of tailoring their mechanical properties. Here, we report self-assembled patterns of Gd nano-fibers in Mg-Gd alloys for the purpose of improving their strength and deformability. 1-nm Gd nano-fibers, with amore » $$\\langle$$c$$\\rangle$$ -rod shape, are formed and hexagonally patterned in association with Gd segregations along dislocations that nucleated during hot extrusion. Such Gd-fiber patterns are able to regulate the relative activities of slips and twinning, as a result, overcome the inherent limitations in strength and ductility of Mg alloys. Finally, this nano-fiber patterning approach could be an effective method to engineer hexagonal metals.« less

Self-patterning Gd nano-fibers in Mg-Gd alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yangxin; Wang, Jian; Chen, Kaiguo

Manipulating the shape and distribution of strengthening units, e.g. particles, fibers, and precipitates, in a bulk metal, has been a widely applied strategy of tailoring their mechanical properties. Here, we report self-assembled patterns of Gd nano-fibers in Mg-Gd alloys for the purpose of improving their strength and deformability. 1-nm Gd nano-fibers, with amore » $$\\langle$$c$$\\rangle$$ -rod shape, are formed and hexagonally patterned in association with Gd segregations along dislocations that nucleated during hot extrusion. Such Gd-fiber patterns are able to regulate the relative activities of slips and twinning, as a result, overcome the inherent limitations in strength and ductility of Mg alloys. Finally, this nano-fiber patterning approach could be an effective method to engineer hexagonal metals.« less

Mechanical, physical and tribological characterization of nano-cellulose fibers reinforced bio-epoxy composites: An attempt to fabricate and scale the 'Green' composite.

PubMed

Barari, Bamdad; Omrani, Emad; Dorri Moghadam, Afsaneh; Menezes, Pradeep L; Pillai, Krishna M; Rohatgi, Pradeep K

2016-08-20

The development of bio-based composites is essential in order to protect the environment while enhancing energy efficiencies. In the present investigation, the plant-derived cellulose nano-fibers (CNFs)/bio-based epoxy composites were manufactured using the Liquid Composite Molding (LCM) process. More specifically, the CNFs with and without chemical modification were utilized in the composites. The curing kinetics of the prepared composites was studied using both the isothermal and dynamic Differential Scanning Calorimetry (DSC) methods. The microstructure as well as the mechanical and tribological properties were investigated on the cured composites in order to understand the structure-property correlations of the composites. The results indicated that the manufactured composites showed improved mechanical and tribological properties when compared to the pure epoxy samples. Furthermore, the chemically modified CNFs reinforced composites outperformed the untreated composites. The surface modification of the fibers improved the curing of the resin by reducing the activation energy, and led to an improvement in the mechanical properties. The CNFs/bio-based epoxy composites form uniform tribo-layer during sliding which minimizes the direct contact between surfaces, thus reducing both the friction and wear of the composites. Copyright © 2016 Elsevier Ltd. All rights reserved.

In-Situ Preparation of Aramid-Multiwalled CNT Nano-Composites: Morphology, Thermal Mechanical and Electric Properties

PubMed Central

Shiju, Jessy; Al-Sagheer, Fakhreia; Bumajdad, Ali; Ahmad, Zahoor

2018-01-01

In this work in-situ polymerization technique has been used to chemically link the functionalized multiwalled carbon nanotubes (CNTs) with aramid matrix chains. Phenylene diamine monomers were reacted in the first stage with the carboxylic acid functionalized CNTs and then amidized in-situ using terephthaloyl chloride generating chemically bonded CNTs with the matrix. Various proportions of the CNTs were used to prepare the hybrid materials. The functionalization procedure was studied by Fourier transform infrared (FTIR) spectroscopy and composite morphology investigated by scanning electron microscopy (SEM). Thermal mechanical properties of these hybrids, together with those where pristine CNTs with similar loadings were used, are compared using tensile and dynamic mechanical analysis (DMA). The tensile strength and temperature involving α-relaxations on CNT loading increased with CNT loading in both systems, but much higher values, i.e., 267 MPa and 353 °C, respectively, were obtained in the chemically bonded system, which are related to the nature of the interface developed as observed in SE micrographs. The water absorption capacity of the films was significantly reduced from 6.2 to 1.45% in the presence pristine CNTs. The inclusion of pristine CNTs increased the electric conductivity of the aramid films with a minimum threshold value at the loading of 3.5 wt % of CNTs. Such mechanically strong and thermally stable aramid and easily processable composites can be suitable for various applications including high performance films, electromagnetic shielding and radar absorption. PMID:29735952

Deposition, clearance, and shortening of Kevlar para-aramid fibrils in acute, subchronic, and chronic inhalation studies in rats.

PubMed

Kelly, D P; Merriman, E A; Kennedy, G L; Lee, K P

1993-10-01

The deposition and clearance of lung-deposited Kevlar para-aramid fibrils (subfibers) have been investigated as part of a subchronic and chronic inhalation toxicity testing program. Fibrils recovered from lung tissue in para-aramid-exposed Sprague-Dawley rats were microscopically counted and measured after exposures to airborne fibrils which were about 12 microns median length (ML) and < 0.3 micron median diameter. In each of three studies lung-recovered fibrils were progressively shorter with increasing residence time in the lungs. Twenty-eight days after a single 6-hr exposure at 400 respirable fibrils per cubic centimeter (f/cm3) the ML of recovered fibrils decreased to about 5 microns. Twenty-four months after a 3-week exposure to 25 or 400 f/cm3, fibrils reached about 2 microns ML. After 2 years of continuous exposure at 2.5, 25, or 100 f/cm3 or 1 year exposure plus 1 year recovery at 400 f/cm3, fibril ML approached 4 microns. In the 2-year study, the lung-fiber accumulation rate/exposure concentration was similar for the three highest concentrations and was about 3 x greater than that seen at 2.5 f/cm3, indicating that concentrations of about 25 f/cm3 or more may overwhelm clearance mechanisms. Time required for fibrils to be reduced to < 5 microns in the lung was markedly less at lower exposure concentration and shorter exposure time. The primary shortening mechanism is proposed to be long fibril cutting by enzymatic attack at fibril defects. However, length-selective fibril deposition and clearance may contribute to shortening in the first few days after exposure. The enzymatic cutting hypothesis is supported by measured increases in numbers of short fibers following cessation of exposures, continued shortening of the fibril length distribution up to 2 years following exposure, and in vitro fibril shortening after 3 months in a proteolytic enzyme preparation. The conclusion is that para-aramid fibrils are less durable in the lungs of rats than expected from

Fracture detection in concrete by glass fiber cloth reinforced plastics

NASA Astrophysics Data System (ADS)

Shin, Soon-Gi; Lee, Sung-Riong

2006-04-01

Two types of carbon (carbon fiber and carbon powder) and a glass cloth were used as conductive phases and a reinforcing fiber, respectively, in polymer rods. The carbon powder was used for fabricating electrically conductive carbon powder-glass fiber reinforced plastic (CP-GFRP) rods. The carbon fiber tows and the CP-GFRP rods were adhered to mortar specimens using epoxy resin and glass fiber cloth. On bending, the electrical resistance of the carbon fiber tow attached to the mortar specimen increased greatly after crack generation, and that of the CP-GFRP rod increased after the early stages of deflection in the mortar. Therefore, the CP-GFRP rod is superior to the carbon fiber tow in detecting fractures. Also, by reinforcing with a glass fiber cloth reinforced plastic, the strength of the mortar specimens became more than twice as strong as that of the unreinforced mortar.

Fabrication of Fiber-Reinforced Celsian Matrix Composites

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Setlock, John A.

2000-01-01

A method has been developed for the fabrication of small diameter, multifilament tow fiber reinforced ceramic matrix composites. Its application has been successfully demonstrated for the Hi-Nicalon/celsian system. Strong and tough celsian matrix composites, reinforced with BN/SiC-coated Hi-Nicalon fibers, have been fabricated by infiltrating the fiber tows with the matrix slurry, winding the tows on a drum, cutting and stacking of the prepreg tapes in the desired orientation, and hot pressing. The monoclinic celsian phase in the matrix was produced in situ, during hot pressing, from the 0.75BaO-0.25SrO-Al2O3-2SiO2 mixed precursor synthesized by solid state reaction from metal oxides. Hot pressing resulted in almost fully dense fiber-reinforced composites. The unidirectional composites having approx. 42 vol% of fibers exhibited graceful failure with extensive fiber pullout in three-point bend tests at room temperature. Values of yield stress and strain were 435 +/- 35 MPa and 0.27 +/- 0.01 percent, respectively, and ultimate strengths of 900 +/- 60 MPa were observed. The Young's modulus of the composites was measured to be 165 +/- 5 GPa.

Nano-yarn carbon nanotube fiber based enzymatic glucose biosensor

NASA Astrophysics Data System (ADS)

Zhu, Zhigang; Song, Wenhui; Burugapalli, Krishna; Moussy, Francis; Li, Ya-Li; Zhong, Xiao-Hua

2010-04-01

A novel brush-like electrode based on carbon nanotube (CNT) nano-yarn fiber has been designed for electrochemical biosensor applications and its efficacy as an enzymatic glucose biosensor demonstrated. The CNT nano-yarn fiber was spun directly from a chemical-vapor-deposition (CVD) gas flow reaction using a mixture of ethanol and acetone as the carbon source and an iron nano-catalyst. The fiber, 28 µm in diameter, was made of bundles of double walled CNTs (DWNTs) concentrically compacted into multiple layers forming a nano-porous network structure. Cyclic voltammetry study revealed a superior electrocatalytic activity for CNT fiber compared to the traditional Pt-Ir coil electrode. The electrode end tip of the CNT fiber was freeze-fractured to obtain a unique brush-like nano-structure resembling a scale-down electrical 'flex', where glucose oxidase (GOx) enzyme was immobilized using glutaraldehyde crosslinking in the presence of bovine serum albumin (BSA). An outer epoxy-polyurethane (EPU) layer was used as semi-permeable membrane. The sensor function was tested against a standard reference electrode. The sensitivities, linear detection range and linearity for detecting glucose for the miniature CNT fiber electrode were better than that reported for a Pt-Ir coil electrode. Thermal annealing of the CNT fiber at 250 °C for 30 min prior to fabrication of the sensor resulted in a 7.5 fold increase in glucose sensitivity. The as-spun CNT fiber based glucose biosensor was shown to be stable for up to 70 days. In addition, gold coating of the electrode connecting end of the CNT fiber resulted in extending the glucose detection limit to 25 µM. To conclude, superior efficiency of CNT fiber for glucose biosensing was demonstrated compared to a traditional Pt-Ir sensor.

Fabricating fiber-reinforced composite posts.

PubMed

Manhart, Jürgen

2011-03-01

Endodontic posts do not increase the strength of the remaining tooth structure in endodontically treated teeth. On the contrary, depending on the post design employed (tapered versus parallel-sided), the root can be weakened relative to the amount of tooth removed during preparation. In many cases, if there has been a high degree of damage to the clinical crown, conservative preparation for an anatomic tapered (biomimetic) post with the incorporation of a ferrule on solid tooth structure is necessary to protect the reaming root structure as well as for the long-term retention of the composite resin core and the definitive restoration. Adhesively luted endodontic posts reinforced with glass or quartz fiber lead to better homogeneous tension distribution when loaded than rigid metal or zirconium oxide ceramic posts. Fiber-reinforced posts also possess advantageous optical properties over metal or metal oxide post systems. The clinician should realize that there are admittedly substantial differences in the mechanical loading capacity of the different fiber-reinforced endodontic posts and should be aware of such differences in order to research and select a suitable post system for use.

All-round joining method with carbon fiber reinforced interface

NASA Astrophysics Data System (ADS)

Miwa, Noriyoshi; Tanaka, Kazunori; Kamiya, Yoshiko; Nishi, Yoshitake

2008-08-01

Carbon fiber reinforced polymer (CFRP) has been recently applied to not only wing, but also fan blades of turbo fan engines. To prevent impact force, leading edge of titanium was often mounted on the CFRP fan blades with adhesive force. In order to enhance the joining strength, a joining method with carbon fiber reinforced interface has been developed. By using nickel-coated carbon fibers, a joining sample with carbon fiber-reinforced interface between CFRP and CFRM has been successfully developed. The joining sample with nickel-coated carbon fiber interface exhibits the high tensile strength, which was about 10 times higher than that with conventional adhesion. On the other hand, Al-welding methods to steel, Cu and Ti with carbon fiber reinforced interface have been successfully developed to lighten the parts of machines of racing car and airplane. Carbon fibers in felt are covered with metals to protect the interfacial reaction. The first step of the welding method is that the Al coated felt is contacted and wrapped with molten aluminum solidified under gravity pressure, whereas the second step is that the felt with double layer of Ni and Al is contacted and wrapped with molten steel (Cu or Ti) solidified under gravity pressure. Tensile strength of Al-Fe (Cu or Ti) welded sample with carbon fiber reinforced interface is higher than those of Al-Fe (Cu or Ti) welded sample.

Retrofit of existing reinforced concrete bridges with fiber reinforced polymer composites

DOT National Transportation Integrated Search

2001-12-01

A two-part research was focused on examining various issues related to the use of fiber reinforced polymer (FRP) composites for strengthening of existing reinforced concrete bridges. A summary of each phase is presented separately.

Studies on mechanical properties of graphene based hybrid composites reinforced with kenaf/glass fiber

NASA Astrophysics Data System (ADS)

Kumar, S. C. Ramesh; Shivanand, H. K.; Vidayasagar, H. N.; Nagabhushan, V.

2018-04-01

The polymer composites are developed with natural fibers and fillers as a alternate material for some of the engineering applications in the field of automobiles and domestic purposes are being investigated. The natural fiber composites such as banana, sisal, jute, coir, kenaf and hemp polymer composites appear more effective due to their lightweight, higher specific strength, biodegradable and cost is low. The main objective is to prepare the Kenaf/Glass fiber hybrid composite filled with graphene as nano filler and to investigate the mechanical properties of hybrid composites. The different types of hybrid composites laminates are fabricated without filler, 0.5, 1 & 1.5Wt % of graphene by using kenaf and glass fiber as reinforcing material with epoxy resin. The specimen were prepared as per the ASTM standards and results shows that the mixing of graphene in epoxy resin improves the mechanical properties of hybrid composites.

Cyanate Ester Resin Modified with Nano-particles for Inclusion in Continuous Fiber Reinforced Composites

DTIC Science & Technology

2011-02-25

thermogravimetric analyzer (TGA) from TA Instruments upon heating at 20 oC/min under air purge. The structural features of the nanoparticles were...low viscosity bisphenol E cyanate ester resin (BECy) resin reinforced with macro scale carbon fibers and negative CTE nanoparticles . Polymer...developed to improve the compatibility of the ZrW2O8 nanoparticles with the polymer matrix. The hybrid composites were prepared with 30 wt

Evaluation of fiber reinforced concrete : final report.

DOT National Transportation Integrated Search

1991-05-01

This study was conducted to evaluate the physical properties of plastic and hardened fiber reinforced concrete using three basic types of fibers: steel, fiberglass and polypropylene. Fibers have been shown to increase flexural and tensile strength, d...

Thermal characteristics of carbon fiber reinforced epoxy containing multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Lee, Jin-woo; Park, Soo-Jeong; Kim, Yun-hae; Riichi-Murakami

2018-06-01

The material with irregular atomic structures such as polymer material exhibits low thermal conductivity because of the complex structural properties. Even materials with same atomic configurations, thermal conductivity may be different based on their structural properties. It is expected that nanoparticles with conductivity will change non-conductive polymer base materials to electrical conductors, and improve the thermal conductivity even with extremely small filling amount. Nano-composite materials contain nanoparticles with a higher surface ratio which makes the higher interface percentage to the total surface of nanoparticles. Therefore, thermal resistance of the interface becomes a dominating factor determines the effective thermal conductivity in nano-composite materials. Carbon fiber has characteristic of resistance or magnetic induction and Also, Carbon nanotube (CNT) has electronic and thermal property. It can be applied for heating system. These characteristic are used as heating composite. In this research, the exothermic characteristics of Carbon fiber reinforced composite added CNT were evaluated depend on CNT length and particle size. It was found that the CNT dispersed in the resin reduces the resistance between the interfaces due to the decrease in the total resistance of the heating element due to the addition of CNTs. It is expected to improve the life and performance of the carbon fiber composite material as a result of the heating element resulting from this paper.

Ceramic fiber reinforced filter

DOEpatents

Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

1991-01-01

A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

Carbon fiber reinforced thermoplastic composites for future automotive applications

NASA Astrophysics Data System (ADS)

Friedrich, K.

2016-05-01

After a brief introduction to polymer composite properties and markets, the state of the art activities in the field of manufacturing of advanced composites for automotive applications are elucidated. These include (a) long fiber reinforced thermoplastics (LFT) for secondary automotive components, and (b) continuous carbon fiber reinforced thermosetting composites for car body applications. It is followed by future possibilities of carbon fiber reinforced thermoplastic composites for e.g. (i) crash elements, (ii) racing car seats, and (iii) production and recycling of automotive fenders.

The inhalation toxicology of p-aramid fibrils.

PubMed

Donaldson, Ken

2009-01-01

The pandemic of lung disease caused by asbestos has cast suspicion on any industrial fibrous material that can become airborne in respirable form in workplaces, such that the respirable fibres might be inhaled. Fibre toxicology arose as a sub-specialty of particle toxicology to address the specialised nature of fibre effects and has evolved substantially in the last 25 years. It has yielded valuable information on the dosimetry, structure-activity relationships, and mechanism involved in toxicological effects of a range of fibrous materials, including asbestos, other naturally occurring fibrous materials, and synthetic vitreous fibres. A robust structure/activity paradigm has emerged from this research that highlights fibre length, thinness, and biopersistence as major factors in determining the pathogenicity of a fibre. p-Aramid is a manufactured fibre composed of synthetic polyamide (poly paraphenylene terephthalamide) manufactured on a commercial scale since 1970 by polymerisation and spinning steps. It is used as an advanced composite and in fabrics, body armour, friction materials, etc. Respirable fibrils of p-aramid can be released from the fibres during working and can become airborne. A considerable body of research has been carried out into the hazard posed by inhaled p-aramid fibrils, and this review considers this body of literature and summarises the state-of-the-science in the toxicology of p-aramid fibrils in the light of the existing overarching fibre toxicology paradigm. The peer-reviewed studies demonstrate that p-aramid fibrils can be long and thin but that the fibrils are not biopersistent. Residence in the milieu of the lungs leads to fibre shortening, allowing efficient and complete phagocytosis and effective clearance. Subsequently the p-aramid hazard is low, and this is confirmed in animal studies. The mechanism of shortening of p-aramid fibrils is not well-understood, but may involve the action of macrophages on the fibrils following

Self-sensing E-glass-fiber-reinforced composites

NASA Astrophysics Data System (ADS)

Brooks, David; Hayes, Simon A.; Khan, N. A.; Zolfaghar, K.; Fernando, Gerard F.

1997-06-01

Conventional E-glass fibers were surface treated to enable them to act as light guides for short distances. The reinforcing fiber light guides were embedded in glass fiber reinforced epoxy prepregs and processed into composites. The resultant composite was termed the self-sensing composite as any damage to these fibers or its interface would result in the attenuation of the transmitted light. Epoxy, silicone, fluoropolymer and sol-gel derived cladding materials were evaluated as potential cladding materials. RFLGs with a silicone coating was found to give the best light transmission. The self-sensing fibers were capable of detecting a 0.5 J direct impact. The feasibility of using the RFLGs for impact damage location was also demonstrated successfully as bleeding-light could be seen in the vicinity of the impact.

Fiber Reinforced Composite Materials Used for Tankage

NASA Technical Reports Server (NTRS)

Cunningham, Christy

2005-01-01

The Nonmetallic Materials and Processes Group is presently working on several projects to optimize cost while providing effect materials for the space program. One factor that must be considered is that these materials must meet certain weight requirements. Composites contribute greatly to this effort. Through the use of composites the cost of launching payloads into orbit will be reduced to one-tenth of the current cost. This research project involved composites used for aluminum pressure vessels. These tanks are used to store cryogenic liquids during flight. The tanks need some type of reinforcement. Steel was considered, but added too much weight. As a result, fiber was chosen. Presently, only carbon fibers with epoxy resin are wrapped around the vessels as a primary source of reinforcement. Carbon fibers are lightweight, yet high strength. The carbon fibers are wet wound onto the pressure vessels. This was done using the ENTEC Filament Winding Machine. It was thought that an additional layer of fiber would aid in reinforcement as well as containment and impact reduction. Kevlar was selected because it is light weight, but five times stronger that steel. This is the same fiber that is used to make bullet-proof vests trampolines, and tennis rackets.

Effect of graphene oxide nano filler on dynamic behaviour of GFRP composites

NASA Astrophysics Data System (ADS)

Pujar, Nagabhushan V.; Nanjundaradhya, N. V.; Sharma, Ramesh S.

2018-04-01

Nano fillers like Alumina oxide, Titanium oxide, Carbon nano tube, Nano clay have been used to improve the mechanical and damping properties of fiber reinforced polymer composites. In the recent years Graphene oxide nano filler is receiving considerable attention for its outstanding properties. Literature available shows that Graphene oxide nano filler can be used to improve the mechanical properties. The use of Graphene oxide in vibration attenuation by enhancing the passive damping in fiber reinforced polymer composite has not been fully explored. The objective of this work is to investigate the dynamic behaviour of Glass fiber-reinforced composite embedded with Graphene oxide nano filler. Graphene oxide is dispersed in epoxy resin with various concentration (0.1%, 0.5% and 1%wt) using ultra-sonification process. Composite laminates were made using the traditional hand-lay-up followed by vacuum bag process. Experimental modal analysis using traditional `strike method' is used to evaluate modal parameters using FFT analyzer and Data Acquisition System. Experiments were carried out for two different fiber orientations viz 0 ➙ & 45 ➙ and two boundary conditions (Free-Free and Cantilever). The modal parameters such as natural frequency, mode shape, damping ratio were studied. This research work demonstrates the vibration damping behaviour with incorporation of Graphene oxide and provides a basic understanding of the damping characteristics in design and manufacture of high performance composites.

Synthesis of HAP nano rods and processing of nano-size ceramic reinforced poly(L)lactic acid composites

NASA Astrophysics Data System (ADS)

Flanigan, Kyle Yusef

2000-09-01

Bone is unique among the various connective tissues in that it is a composite of organic and inorganic components. Calcium phosphates occur principally in the form of hydroxyapatite crystals {Ca10(PO4) 6(OH)2}. Secreted apatite crystals are integral to the structural rigidity of the bone. When a bone breaks, there is often a need to implant an orthotic device to support the broken bone during remodeling. Current technologies use either metal pins and screws that need to be removed (by surgery) once the healing is complete or polymeric materials that either get resorbed or are porous enough to allow bone ingrowth. Poly(L)Lactic acid and copolymers of polyglycolic acid (PGA) are thermoplastics which show promise as the matrix material in biosorbable/load bearing implants. In service this material is hydrolyzed generating water and L-lactate. Orthoses composed of neat PLLA resins require greater than three years for complete resorbtion, however; 95% of strength is lost in 2 to 3 weeks in-vitro. This has limited the deployment of load bearing PLLA to screws, pins or short bracing spans. There exists a need for the development of an implantable and biosorbable orthotic device which will retain its structural integrity long enough for remodeling and healing process to generate new bone material, about 10 weeks. The scope of this dissertation is the development of HAP nano-whisker reinforcement and a HAP/PLLA thermoplastic composite. As proof of the feasibility of generating nano-reinforcement PLLA-composites, the surface of a galleried clay, montmorillonite, was modified and clay/PLLA composites processed and then characterized. Hydroxyapatite nano-whiskers were synthesized and functionalized using organosilanes and Menhaden fish-oil (common organic dispersant). The functionalized nano-fibers were used to process HAP/PLLA composites. Characterization techniques included thermal analysis, magnetic spectroscopy, XRD and ICP analysis and electron microscopy. The

Fire test method for graphite fiber reinforced plastics

NASA Technical Reports Server (NTRS)

Bowles, K. J.

1980-01-01

A potential problem in the use of graphite fiber reinforced resin matrix composites is the dispersal of graphite fibers during accidential fires. Airborne, electrically conductive fibers originating from the burning composites could enter and cause shorting in electrical equipment located in surrounding areas. A test method for assessing the burning characteristics of graphite fiber reinforced composites and the effectiveness of the composites in retaining the graphite fibers has been developed. The method utilizes a modified rate of heat release apparatus. The equipment and the testing procedure are described. The application of the test method to the assessment of composite materials is illustrated for two resin matrix/graphite composite systems.

The use of chitosan/PLA nano-fibers by emulsion eletrospinning for periodontal tissue engineering.

PubMed

Shen, Renze; Xu, Weihong; Xue, Yanxiang; Chen, Luyuan; Ye, Haicheng; Zhong, Enyi; Ye, Zhanchao; Gao, Jie; Yan, Yurong

2018-04-16

In this study, nanofibrous scaffolds base on pure polylactic acid (PLA) and chitosan/PLA blends were fabricated by emulsion eletrospinning. By modulating their mechanical and biological properties, cell-compatible and biodegradable scaffolds were developed for periodontal bone regeneration. Pure PLA and different weight ratios of chitosan nano-particle/PLA nano-fibers were fabricated by emulsion eletrospinning. Scanning electron microscope (SEM) was performed to observe the morphology of nano-fibers. Mechanical properties of nano-fibers were tested by single fiber strength tester. Hydrophilic/hydrophobic nature of the nano-fibers was observed by stereomicroscope. In vitro degradation was also tested. Cells were seeded on nano-fibers scaffolds. Changes in cell adhesion, proliferation and osteogenic differentiation were tested by MTT assay and Alizarin Red S staining. Reverse transcription-polymerase chain reaction (RT-PCR) assay was used to evaluate the expression of (Toll-like receptor 4) TLR4, IL-6, IL-8, IL-1β, OPG, RUNX2 mRNA. It is shown that the mean diameter of nano-fibers is about 200 nm. The mean diameter of chitosan nano-particles is about 50 nm. The combination of chitosan nano-particles enhanced the mechanical properties of pure PLA nano-fibers. By adding a certain amount of chitosan nano-particles, it promoted cell adhesion. It also promoted the osteogenic differentiation of bone marrow stem cells (BMSCs) by elevating the expression of osteogenic marker genes such as BSP, Ocn, collagen I, and OPN and enhanced ECM mineralization. Nonetheless, it caused higher expression of inflammatory mediators and TLR4 of human periodontal ligament cells (hPDLCs). The combination of chitosan nano-particles enhanced the mechanical properties of pure PLA nano-fibers and increased its hydrophilicity. Pure PLA nano-fibers scaffold facilitated BMSCs proliferation. Adding an appropriate amount of chitosan nano-particles may promote its properties of cell proliferation

Analytical, Numerical and Experimental Examination of Reinforced Composites Beams Covered with Carbon Fiber Reinforced Plastic

NASA Astrophysics Data System (ADS)

Kasimzade, A. A.; Tuhta, S.

2012-03-01

In the article, analytical, numerical (Finite Element Method) and experimental investigation results of beam that was strengthened with fiber reinforced plastic-FRP composite has been given as comparative, the effect of FRP wrapping number to the maximum load and moment capacity has been evaluated depending on this results. Carbon FRP qualitative dependences have been occurred between wrapping number and beam load and moment capacity for repair-strengthen the reinforced concrete beams with carbon fiber. Shown possibilities of application traditional known analysis programs, for the analysis of Carbon Fiber Reinforced Plastic (CFRP) strengthened structures.

Improved Sectional Image Analysis Technique for Evaluating Fiber Orientations in Fiber-Reinforced Cement-Based Materials.

PubMed

Lee, Bang Yeon; Kang, Su-Tae; Yun, Hae-Bum; Kim, Yun Yong

2016-01-12

The distribution of fiber orientation is an important factor in determining the mechanical properties of fiber-reinforced concrete. This study proposes a new image analysis technique for improving the evaluation accuracy of fiber orientation distribution in the sectional image of fiber-reinforced concrete. A series of tests on the accuracy of fiber detection and the estimation performance of fiber orientation was performed on artificial fiber images to assess the validity of the proposed technique. The validation test results showed that the proposed technique estimates the distribution of fiber orientation more accurately than the direct measurement of fiber orientation by image analysis.

Improved Sectional Image Analysis Technique for Evaluating Fiber Orientations in Fiber-Reinforced Cement-Based Materials

PubMed Central

Lee, Bang Yeon; Kang, Su-Tae; Yun, Hae-Bum; Kim, Yun Yong

2016-01-01

The distribution of fiber orientation is an important factor in determining the mechanical properties of fiber-reinforced concrete. This study proposes a new image analysis technique for improving the evaluation accuracy of fiber orientation distribution in the sectional image of fiber-reinforced concrete. A series of tests on the accuracy of fiber detection and the estimation performance of fiber orientation was performed on artificial fiber images to assess the validity of the proposed technique. The validation test results showed that the proposed technique estimates the distribution of fiber orientation more accurately than the direct measurement of fiber orientation by image analysis. PMID:28787839

Dynamic stability of nano-fibers self-assembled from short amphiphilic A6D peptides

NASA Astrophysics Data System (ADS)

Nikoofard, Narges; Maghsoodi, Fahimeh

2018-04-01

Self-assembly of A6D amphiphilic peptides in explicit water is studied by using coarse-grained molecular dynamics simulations. It is observed that the self-assembly of randomly distributed A6D peptides leads to the formation of a network of nano-fibers. Two other simulations with cylindrical nano-fibers as the initial configuration show the dynamic stability of the self-assembled nano-fibers. As a striking feature, notable fluctuations occur along the axes of the nano-fibers. Depending on the number of peptides per unit length of the nano-fiber, flat-shaped bulges or spiral shapes along the nano-fiber axis are observed at the fluctuations. Analysis of the particle distribution around the nano-fiber indicates that the hydrophobic core and the hydrophilic shell of the nano-structure are preserved in both simulations. The size of the deformations and their correlation times are different in the two simulations. This study gives new insights into the dynamics of the self-assembled nano-structures of short amphiphilic peptides.

Dynamic stability of nano-fibers self-assembled from short amphiphilic A6D peptides.

PubMed

Nikoofard, Narges; Maghsoodi, Fahimeh

2018-04-07

Self-assembly of A 6 D amphiphilic peptides in explicit water is studied by using coarse-grained molecular dynamics simulations. It is observed that the self-assembly of randomly distributed A 6 D peptides leads to the formation of a network of nano-fibers. Two other simulations with cylindrical nano-fibers as the initial configuration show the dynamic stability of the self-assembled nano-fibers. As a striking feature, notable fluctuations occur along the axes of the nano-fibers. Depending on the number of peptides per unit length of the nano-fiber, flat-shaped bulges or spiral shapes along the nano-fiber axis are observed at the fluctuations. Analysis of the particle distribution around the nano-fiber indicates that the hydrophobic core and the hydrophilic shell of the nano-structure are preserved in both simulations. The size of the deformations and their correlation times are different in the two simulations. This study gives new insights into the dynamics of the self-assembled nano-structures of short amphiphilic peptides.

Detection of defects in multi-layered aramid composites by ultrasonic IR thermography

NASA Astrophysics Data System (ADS)

Pracht, Monika; Swiderski, Waldemar

2017-10-01

In military applications, laminates reinforced with aramid, carbon, and glass fibers are used for the construction of protection products against light ballistics. Material layers can be very different by their physical properties. Therefore, such materials represent a difficult inspection task for many traditional techniques of non-destructive testing (NDT). Defects which can appear in this type of many-layered composite materials usually are inaccuracies in gluing composite layers and stratifications or delaminations occurring under hits of fragments and bullets. IR thermographic NDT is considered as a candidate technique to detect such defects. One of the active IR thermography methods used in nondestructive testing is vibrothermography. The term vibrothermography was created in the 1990s to determine the thermal test procedures designed to assess the hidden heterogeneity of structural materials based on surface temperature fields at cyclical mechanical loads. A similar procedure can be done with sound and ultrasonic stimulation of the material, because the cause of an increase in temperature is internal friction between the wall defect and the stimulation mechanical waves. If the cyclic loading does not exceed the flexibility of the material and the rate of change is not large, the heat loss due to thermal conductivity is small, and the test object returns to its original shape and temperature. The most commonly used method is ultrasonic stimulation, and the testing technique is ultrasonic infrared thermography. Ultrasonic IR thermography is based on two basic phenomena. First, the elastic properties of defects differ from the surroundings, and acoustic damping and heating are always larger in the damaged regions than in the undamaged or homogeneous areas. Second, the heat transfer in the sample is dependent on its thermal properties. In this paper, both modelling and experimental results which illustrate the advantages and limitations of ultrasonic IR

Compressive Behavior of Fiber-Reinforced Concrete with End-Hooked Steel Fibers.

PubMed

Lee, Seong-Cheol; Oh, Joung-Hwan; Cho, Jae-Yeol

2015-03-27

In this paper, the compressive behavior of fiber-reinforced concrete with end-hooked steel fibers has been investigated through a uniaxial compression test in which the variables were concrete compressive strength, fiber volumetric ratio, and fiber aspect ratio (length to diameter). In order to minimize the effect of specimen size on fiber distribution, 48 cylinder specimens 150 mm in diameter and 300 mm in height were prepared and then subjected to uniaxial compression. From the test results, it was shown that steel fiber-reinforced concrete (SFRC) specimens exhibited ductile behavior after reaching their compressive strength. It was also shown that the strain at the compressive strength generally increased along with an increase in the fiber volumetric ratio and fiber aspect ratio, while the elastic modulus decreased. With consideration for the effect of steel fibers, a model for the stress-strain relationship of SFRC under compression is proposed here. Simple formulae to predict the strain at the compressive strength and the elastic modulus of SFRC were developed as well. The proposed model and formulae will be useful for realistic predictions of the structural behavior of SFRC members or structures.

Compressive Behavior of Fiber-Reinforced Concrete with End-Hooked Steel Fibers

PubMed Central

Lee, Seong-Cheol; Oh, Joung-Hwan; Cho, Jae-Yeol

2015-01-01

In this paper, the compressive behavior of fiber-reinforced concrete with end-hooked steel fibers has been investigated through a uniaxial compression test in which the variables were concrete compressive strength, fiber volumetric ratio, and fiber aspect ratio (length to diameter). In order to minimize the effect of specimen size on fiber distribution, 48 cylinder specimens 150 mm in diameter and 300 mm in height were prepared and then subjected to uniaxial compression. From the test results, it was shown that steel fiber-reinforced concrete (SFRC) specimens exhibited ductile behavior after reaching their compressive strength. It was also shown that the strain at the compressive strength generally increased along with an increase in the fiber volumetric ratio and fiber aspect ratio, while the elastic modulus decreased. With consideration for the effect of steel fibers, a model for the stress–strain relationship of SFRC under compression is proposed here. Simple formulae to predict the strain at the compressive strength and the elastic modulus of SFRC were developed as well. The proposed model and formulae will be useful for realistic predictions of the structural behavior of SFRC members or structures. PMID:28788011

Mechanical recycling of continuous fiber-reinforced thermoplastic sheets

NASA Astrophysics Data System (ADS)

Moritzer, Elmar; Heiderich, Gilmar

2016-03-01

This contribution examines possible material recycling of offcuts generated during the production of continuous-fiber-reinforced composite sheets. These sheets consist of a polyamide 6 matrix and glass fiber fabric. In the initial step, the offcut is shredded to obtain particles; following that, the particles are processed in a twin-screw process to produce fiber-reinforced plastic pellets with varying fiber contents. These pellets are intended for use in injection molding processes as a substitution for new raw materials. This investigation centers on the mechanical properties which can be achieved with the recycled material after both the twin-screw process and injection molding.

Discontinuous Fiber-reinforced Composites above Critical Length

PubMed Central

Petersen, R.C.

2014-01-01

Micromechanical physics of critical fiber length, describing a minimum filament distance for resin impregnation and stress transfer, has not yet been applied in dental science. As a test of the hypothesis that 9-micron-diameter, 3-mm-long quartz fibers would increase mechanical strength over particulate-filled composites, photocure-resin-pre-impregnated discontinuous reinforcement was incorporated at 35 wt% into 3M Corporation Z100, Kerr Corporation HerculiteXRV, and an experimental photocure paste with increased radiopaque particulate. Fully articulated four-point bend testing per ASTM C 1161-94 for advanced ceramics and Izod impact testing according to a modified unnotched ASTM D 256-00 specification were then performed. All photocure-fiber-reinforced composites demonstrated significant improvements over particulate-filled compounds (p < 0.001) for flexural strength, modulus, work of fracture, strain at maximum load, and Izod toughness, with one exception for the moduli of Z100 and the experimental reinforced paste. The results indicate that inclusion of pre-impregnated fibers above the critical aspect ratio yields major advancements regarding the mechanical properties tested. PMID:15790745

Shear transfer in concrete reinforced with carbon fibers

NASA Astrophysics Data System (ADS)

El-Mokadem, Khaled Mounir

2001-10-01

Scope and method of study. The research started with preliminary tests and studies on the behavior and effect of carbon fibers in different water solutions and mortar/concrete mixes. The research work investigated the use of CF in the production of concrete pipes and prestressed concrete double-tee sections. The research then focused on studying the effect of using carbon fibers on the direct shear transfer of sand-lightweight reinforced concrete push-off specimens. Findings and conclusions. In general, adding carbon fibers to concrete improved its tensile characteristics but decreased its compressive strength. The decrease in compressive strength was due to the decrease in concrete density as fibers act as three-dimensional mesh that entrapped air. The decrease in compressive strength was also due to the increase in the total surface area of non-cementitious material in the concrete. Sand-lightweight reinforced concrete push-off specimens with carbon fibers had lower shear carrying capacity than those without carbon fibers for the same cement content in the concrete. Current building codes and specifications estimate the shear strength of concrete as a ratio of the compressive strength. If applying the same principals then the ratio of shear strength to compressive strength for concrete reinforced with carbon fibers is higher than that for concrete without carbon fibers.

Advance study of fiber-reinforced self-compacting concrete

NASA Astrophysics Data System (ADS)

Mironova, M.; Ivanova, M.; Naidenov, V.; Georgiev, I.; Stary, J.

2015-10-01

Incorporation in concrete composition of steel macro- and micro - fiber reinforcement with structural function increases the degree of ductility of typically brittle cement-containing composites, which in some cases can replace completely or partially conventional steel reinforcement in the form of rods and meshes. Thus, that can reduce manufacturing, detailing and placement of conventional reinforcement, which enhances productivity and economic efficiency of the building process. In this paper, six fiber-reinforced with different amounts of steel fiber cement-containing self-compacting compositions are investigated. The results of some of their main strength-deformation characteristics are presented. Advance approach for the study of structural and material properties of these type composites is proposed by using the methods of industrial computed tomography. The obtained original tomography results about the microstructure and characteristics of individual structural components make it possible to analyze the effective macro-characteristics of the studied composites. The resulting analytical data are relevant for the purposes of multi-dimensional modeling of these systems. Multifactor structure-mechanical analysis of the obtained with different methods original scientific results is proposed. It is presented a conclusion of the capabilities and effectiveness of complex analysis in the studies to characterize the properties of self-compacting fiber-reinforced concrete.

Advance study of fiber-reinforced self-compacting concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mironova, M., E-mail: mirona@imbm.bas.bg; Ivanova, M., E-mail: magdalena.ivanova@imbm.bas.bg; Naidenov, V., E-mail: valna53@mail.bg

2015-10-28

Incorporation in concrete composition of steel macro- and micro – fiber reinforcement with structural function increases the degree of ductility of typically brittle cement-containing composites, which in some cases can replace completely or partially conventional steel reinforcement in the form of rods and meshes. Thus, that can reduce manufacturing, detailing and placement of conventional reinforcement, which enhances productivity and economic efficiency of the building process. In this paper, six fiber-reinforced with different amounts of steel fiber cement-containing self-compacting compositions are investigated. The results of some of their main strength-deformation characteristics are presented. Advance approach for the study of structural andmore » material properties of these type composites is proposed by using the methods of industrial computed tomography. The obtained original tomography results about the microstructure and characteristics of individual structural components make it possible to analyze the effective macro-characteristics of the studied composites. The resulting analytical data are relevant for the purposes of multi-dimensional modeling of these systems. Multifactor structure-mechanical analysis of the obtained with different methods original scientific results is proposed. It is presented a conclusion of the capabilities and effectiveness of complex analysis in the studies to characterize the properties of self-compacting fiber-reinforced concrete.« less

Fire test method for graphite fiber reinforced plastics

NASA Technical Reports Server (NTRS)

Bowles, K. J.

1980-01-01

A potential problem in the use of graphite fiber reinforced resin matrix composites is the dispersal of graphite fibers during accidental fires. Airborne, electrically conductive fibers originating from the burning composites could enter and cause shorting in electrical equipment located in surrounding areas. A test method for assessing the burning characteristics of graphite fiber reinforced composites and the effectiveness of the composites in retaining the graphite fibers has been developed. The method utilizes a modified Ohio State University Rate of Heat Release apparatus. The equipment and the testing procedure are described. The application of the test method to the assessment of composite materials is illustrated for two resin matrix/graphite composite systems.

Hi-Nicalon Fiber-Reinforced Celsian Matrix Composites: Influence of Interface Modification

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Eldridge, Jeffrey I.

1998-01-01

Unidirectional celsian matrix composites having 42-45 vol % of uncoated or BN-SIC coated Hi-Nicalon fibers were tested in three-point bend at room temperature. The uncoated fiber-reinforced composites showed catastrophic failure with strength of 210 35 MPa and a flat fracture surface. In contrast, composites reinforced with coated fibers exhibited graceful failure with extensive fiber pullout. Values of first matrix cracking stress and strain were 435 +/- 35 MPa and 0.27 +/- 0.01%, respectively, with ultimate strength as high as 960 MPa. The elastic Young modulus of the uncoated and coated fiber-reinforced composites were 184 +/- 4 GPa and 165 +/- 5 GPa, respectively. Fiber push-through tests and microscopic examination indicated no chemical reaction at the uncoated or coated fiber-matrix interface. The low strength of composite with uncoated fibers is due to degradation of the fiber strength from mechanical damage during processing. Because both the coated- and uncoated-fiber-reinforced composites exhibited weak interfaces, the beneficial effect of the BN-SIC dual layer is primarily the protection of fibers from mechanical damage during processing.

Glass fiber reinforced polymer bars as top mat reinforcement for bridge decks.

DOT National Transportation Integrated Search

2002-01-01

The objectives of this research were to characterize the material and bond properties of three commercially available GFRP (glass fiber reinforced polymer) reinforcing bars, and evaluate the effects of the material properties and the current ACI desi...

Bio-Based Nanocomposites: An Alternative to Traditional Composites

ERIC Educational Resources Information Center

Tate, Jitendra S.; Akinola, Adekunle T.; Kabakov, Dmitri

2009-01-01

Polymer matrix composites (PMC), often referred to as fiber reinforced plastics (FRP), consist of fiber reinforcement (E-glass, S2-glass, aramid, carbon, or natural fibers) and polymer matrix/resin (polyester, vinyl ester, polyurethane, phenolic, and epoxies). Eglass/ polyester and E-glass/vinyl ester composites are extensively used in the marine,…

Static and cyclic loading of fiber-reinforced dental resin.

PubMed

Drummond, James L; Bapna, Mahendra S

2003-05-01

The aim of this study was to evaluate the flexure strength of unidirectional fiber-reinforced resins under static and cyclic loading with and without thermal cycling. The fiber-reinforced resin materials chosen for this project were commercially available endodontic posts and commercially procured bar samples. For all materials, controls for flexure strength were tested in air and in water using three-point loading. Specimens were thermal cycled between 7 and 63 degrees C for 6000 cycles. A staircase approach was used to determine the flexure fatigue limit and scanning microscopy was used to examine the microstructure. The carbon/graphite fiber-reinforced resin posts and the glass FiberKor posts were significantly stronger than the ceramic (zirconia) and the other glass-reinforced resin materials. Thermal cycling caused a significant lowering (11-24%) of the flexure strength for each resin based post system. The ceramic post system decreased only by 2%. Further, for standard size glass fiber-reinforced resin bars, no significant differences between testing in air and water was observed, but a significant difference between static and cyclic loading was noted. The decreases in the strength property due to thermal cycling and the cyclic loading of these materials indicates that their utilization in the oral environment enhances their degradation, and potentially shortens their clinical life.

Thermal oxidation induced degradation of carbon fiber reinforced composites and carbon nanotube sheet enhanced fiber/matrix interface for high temperature aerospace structural applications

NASA Astrophysics Data System (ADS)

Haque, Mohammad Hamidul

Recent increase in the use of carbon fiber reinforced polymer matrix composite, especially for high temperature applications in aerospace primary and secondary structures along with wind energy and automotive industries, have generated new challenges to predict its failure mechanisms and service life. This dissertation reports the experimental study of a unidirectional carbon fiber reinforced bismaleimide (BMI) composites (CFRC), an excellent candidate for high temperature aerospace components, undergoing thermal oxidation at 260 °C in air for over 3000 hours. The key focus of the work is to investigate the mechanical properties of the carbon fiber BMI composite subjected to thermal aging in three key aspects - first, studying its bulk flexural properties (in macro scale), second, characterizing the crack propagation along the fiber direction, representing the interfacial bonding strength between fiber and matrix (in micro scale), and third, introducing nano-structured materials to modify the interface (in nano scale) between the carbon fiber and BMI resin and mechanical characterization to study its influence on mitigating the aging effect. Under the first category, weight loss and flexural properties have been monitored as the oxidation propagates through the fiber/matrix interface. Dynamic mechanical analysis and micro-computed tomography analysis have been performed to analyze the aging effects. In the second category, the long-term effects of thermal oxidation on the delamination (between the composite plies) and debonding (between fiber and matrix) type fracture toughness have been characterized by preparing two distinct types of double cantilever beam specimens. Digital image correlation has been used to determine the deformation field and strain distribution around the crack propagation path. Finally the resin system and the fiber/matrix interface have been modified using nanomaterials to mitigate the degradations caused by oxidation. Nanoclay modified

Zinc Oxide Nanowire Interphase for Enhanced Lightweight Polymer Fiber Composites

NASA Technical Reports Server (NTRS)

Sodano, Henry A.; Brett, Robert

2011-01-01

The objective of this work was to increase the interfacial strength between aramid fiber and epoxy matrix. This was achieved by functionalizing the aramid fiber followed by growth of a layer of ZnO nanowires on the fiber surface such that when embedded into the polymer, the load transfer and bonding area could be substantially enhanced. The functionalization procedure developed here created functional carboxylic acid surface groups that chemically interact with the ZnO and thus greatly enhance the strength of the interface between the fiber and the ZnO.

Sensored fiber reinforced polymer grate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, Michael P.; Mack, Thomas Kimball

Various technologies described herein pertain to a sensored grate that can be utilized for various security fencing applications. The sensored grate includes a grate framework and an embedded optical fiber. The grate framework is formed of a molded polymer such as, for instance, molded fiber reinforced polymer. Further, the grate framework includes a set of elongated elements, where the elongated elements are spaced to define apertures through the grate framework. The optical fiber is embedded in the elongated elements of the grate framework. Moreover, bending or breaking of one or more of the elongated elements can be detected based onmore » a change in a characteristic of input light provided to the optical fiber compared to output light received from the optical fiber.« less

Properties of indirect composites reinforced with monomer-impregnated glass fiber.

PubMed

Tanoue, Naomi; Sawase, Takashi; Matsumura, Hideo; McCabe, John F

2012-07-01

Sufficient flexural strength is required for long-term clinical use of fixed partial dentures made with fiber-reinforced composite. The flexural strengths of indirect composite materials reinforced with a monomer-preimpregnated glass fiber material were determined to evaluate the compatibility of the composites to glass fiber material. Four types (microhybrid, nanohybrid, microfilled, and minifilled) of indirect composites and a unidirectional long glass fiber material were selected for investigation. The composites were placed on a fiber plate and polymerized in accordance with the respective manufacturer's instructions. Rectangular bar fiber-composite specimens were machined and the flexural strength was calculated. The flexural strength of each indirect composite was also measured. The microfilled composite with the lowest filler content (70 wt%) exhibited the highest increase ratio using the fiber, although its strength without fiber reinforcement was the lowest (62.1 MPa). The fiber-microhybrid specimen demonstrated the highest mean strength (355.9 MPa), although the filler content of the microhybrid composite was comparatively low (73 wt%). The type of composite material should be considered for the selection of an optimal fiber-composite combination.

Carbon Fiber Reinforced Polymer Grids for Shear and End Zone Reinforcement in Bridge Beams

DOT National Transportation Integrated Search

2018-01-01

Corrosion of reinforcing steel reduces life spans of bridges throughout the United States; therefore, using non-corroding carbon fiber reinforced polymer (CFRP) reinforcement is seen as a way to increase service life. The use of CFRP as the flexural ...

Carbon Fiber Reinforced Ceramic Composites for Propulsion Applications

NASA Technical Reports Server (NTRS)

Freedman, Marc (Technical Monitor); Shivakumar, Kunigal N.

2003-01-01

Fiber reinforced ceramic composites are materials of choice for gas turbine engines because of their high thermal efficiency, thrust/weight ratio, and operating temperatures. However, the successful introduction of ceramic composites to hot structures is limited because of excessive cost of manufacturing, reproducibility, nonuniformity, and reliability. Intense research is going on around the world to address some of these issues. The proposed effort is to develop a comprehensive status report of the technology on processing, testing, failure mechanics, and environmental durability of carbon fiber reinforced ceramic composites through extensive literature study, vendor and end-user survey, visits to facilities doing this type of work, and interviews. Then develop a cooperative research plan between NASA GRC and NCA&T (Center for Composite Materials Research) for processing, testing, environmental protection, and evaluation of fiber reinforced ceramic composites.

Damping properties of fiber reinforced composite suitable for stayed cable

NASA Astrophysics Data System (ADS)

Li, Jianzhi; Sun, Baochen; Du, Yanliang

2011-11-01

Carbon fiber reinforced plastics (CFRP) cables were initially most investigated to replace steel cables. To further explore the advantages of FRP cables, the potential ability of vibration control is studied in this paper emphasizing the designable characteristic of hybrid FRP cables. Fiber reinforced vinyl ester composites and fiber reinforced epoxy composites were prepared by the pultrusion method. Due to the extensive application of fiber reinforced composites, the temperature spectrum and frequency spectrum of loss factor for the composite were tested using dynamic mechanical analysis (DMA) equipment. The damping properties and damping mechanism of the composite were investigated and discussed at different temperatures and frequencies. The result indicates that the loss factor of the composites is increasing with the increase of the frequency from 0.1Hz to 2 Hz and decreasing with the decrease of the temperature from -20°C to 60°C. The loss factor of the carbon fiber composite is higher than that of the glass fiber for the same matrix. The loss factor of the vinyl ester composite is higher than that of the epoxy composite for the same fiber.

Damping properties of fiber reinforced composite suitable for stayed cable

NASA Astrophysics Data System (ADS)

Li, Jianzhi; Sun, Baochen; Du, Yanliang

2012-04-01

Carbon fiber reinforced plastics (CFRP) cables were initially most investigated to replace steel cables. To further explore the advantages of FRP cables, the potential ability of vibration control is studied in this paper emphasizing the designable characteristic of hybrid FRP cables. Fiber reinforced vinyl ester composites and fiber reinforced epoxy composites were prepared by the pultrusion method. Due to the extensive application of fiber reinforced composites, the temperature spectrum and frequency spectrum of loss factor for the composite were tested using dynamic mechanical analysis (DMA) equipment. The damping properties and damping mechanism of the composite were investigated and discussed at different temperatures and frequencies. The result indicates that the loss factor of the composites is increasing with the increase of the frequency from 0.1Hz to 2 Hz and decreasing with the decrease of the temperature from -20°C to 60°C. The loss factor of the carbon fiber composite is higher than that of the glass fiber for the same matrix. The loss factor of the vinyl ester composite is higher than that of the epoxy composite for the same fiber.

Tensile Properties of Dyneema SK76 Single Fibers at Multiple Loading Rates Using a Direct Gripping Method

DTIC Science & Technology

2014-06-01

lower density compared with aramid fibers such as Kevlar and Twaron. Numerical modeling is used to design more effective fiber-based composite armor...in measuring fibers and doing experiments. vi INTENTIONALLY LEFT BLANK. 1 1. Introduction Aramid fibers such as Kevlar (DuPont) and Twaron...methyl methacrylate blocks. The efficacy of this method to grip Kevlar fibers has been rigorously studied using a variety of statistical methods at

Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors.

PubMed

Montanini, Roberto; Recupero, Antonino; De Domenico, Fabrizio; Freni, Fabrizio

2016-09-22

Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data.

Influence of fibre reinforcement on selected mechanical properties of dental composites.

PubMed

Niewczas, Agata M; Zamościńska, Jolanta; Krzyżak, Aneta; Pieniak, Daniel; Walczak, Agata; Bartnik, Grzegorz

2017-01-01

For splinting or designing adhesive bridges, reconstructive composite structures with increased mechanical properties owing to embedded reinforcement fibres are used. The aim of this article was to determine the influence of glass and aramid fibres on the mechanical strength of composites reinforced with these fibres. Two polymer-ceramic microhybrid materials: Boston and Herculite were tested. Three types of reinforcement fibres were used: aramid (Podwiązka) with a single layer weave, a single layer weave glass fibre (FSO) and triple layer weave glass fibre (FSO evo). Tests were conducted in accordance with the requirements of ISO 4049:2009. The following material types were chosen for research: Boston, Boston + Podwiązka, Herculite, Herculite + Podwiązka, Herculite + FSO and Herculite + FSO evo. The scope of research included: flexural strength B, bending modulus of elasticity εB and work to failure of the reinforced composite Wfb. Additionally, microscopic observations of fracture occurring in samples were made. In comparison: the Herculite (97.7 MPa) type with the Herculite + FSO evo (177.5 MPa) type was characterized by the highest strength. Fibre reinforcement resulted in decreasing the elasticity modulus: Herculite + reinforcement (6.86 GPa; 6.33 GPa; 6.11 GPa) in comparison with the Herculite (9.84 GPa) and respectively Boston + reinforcement (10.08 GPa) as compared with the Boston (11.81 GPa). Using glass fibres increases flexural strength of the test composites. Using aramid fibres does not change their strength. The elasticity modulus of the reinforced reconstructive structures decreases after application of either type of fibres. However, their resistance to the crack initiation increases.

Modeling of short fiber reinforced injection moulded composite

NASA Astrophysics Data System (ADS)

Kulkarni, A.; Aswini, N.; Dandekar, C. R.; Makhe, S.

2012-09-01

A micromechanics based finite element model (FEM) is developed to facilitate the design of a new production quality fiber reinforced plastic injection molded part. The composite part under study is composed of a polyetheretherketone (PEEK) matrix reinforced with 30% by volume fraction of short carbon fibers. The constitutive material models are obtained by using micromechanics based homogenization theories. The analysis is carried out by successfully coupling two commercial codes, Moldflow and ANSYS. Moldflow software is used to predict the fiber orientation by considering the flow kinetics and molding parameters. Material models are inputted into the commercial software ANSYS as per the predicted fiber orientation and the structural analysis is carried out. Thus in the present approach a coupling between two commercial codes namely Moldflow and ANSYS has been established to enable the analysis of the short fiber reinforced injection moulded composite parts. The load-deflection curve is obtained based on three constitutive material model namely an isotropy, transversely isotropy and orthotropy. Average values of the predicted quantities are compared to experimental results, obtaining a good correlation. In this manner, the coupled Moldflow-ANSYS model successfully predicts the load deflection curve of a composite injection molded part.

Mechanical characterization of glass fiber (woven roving/chopped strand mat E-glass fiber) reinforced polyester composites

NASA Astrophysics Data System (ADS)

Bhaskar, V. Vijaya; Srinivas, Kolla

2017-07-01

Polymer reinforced composites have been replacing most of the engineering material and their applications become more and more day by day. Polymer composites have been analyzing from past thirty five years for their betterment for adapting more applications. This paper aims at the mechanical properties of polyester reinforced with glass fiber composites. The glass fiber is reinforced with polyester in two forms viz Woven Rovings (WRG) and Chopped Strand Mat (CSMG) E-glass fibers. The composites are fabricated by hand lay-up technique and the composites are cut as per ASTM Standard sizes for corresponding tests like flexural, compression and impact tests, so that flexural strength, compression strength, impact strength and inter laminar shear stress(ILSS) of polymer matrix composites are analyzed. From the tests and further calculations, the polyester composites reinforced with Chopped Strand Mat glass fiber have shown better performance against flexural load, compression load and impact load than that of Woven Roving glass fiber.

Strain measurement in a concrete beam by use of the Brillouin-scattering-based distributed fiber sensor with single-mode fibers embedded in glass fiber reinforced polymer rods and bonded to steel reinforcing bars.

PubMed

Zeng, Xiaodong; Bao, Xiaoyi; Chhoa, Chia Yee; Bremner, Theodore W; Brown, Anthony W; DeMerchant, Michael D; Ferrier, Graham; Kalamkarov, Alexander L; Georgiades, Anastasis V

2002-08-20

The strain measurement of a 1.65-m reinforced concrete beam by use of a distributed fiber strain sensor with a 50-cm spatial resolution and 5-cm readout resolution is reported. The strain-measurement accuracy is +/-15 microepsilon (microm/m) according to the system calibration in the laboratory environment with non-uniform-distributed strain and +/-5 microepsilon with uniform strain distribution. The strain distribution has been measured for one-point and two-point loading patterns for optical fibers embedded in pultruded glass fiber reinforced polymer (GFRP) rods and those bonded to steel reinforcing bars. In the one-point loading case, the strain deviations are +/-7 and +/-15 microepsilon for fibers embedded in the GFRP rods and fibers bonded to steel reinforcing bars, respectively, whereas the strain deviation is +/-20 microepsilon for the two-point loading case.

Fiber-reinforced superalloy composites provide an added performance edge

NASA Technical Reports Server (NTRS)

Petrasek, D. W.; Mcdaniels, D. L.; Westfall, L. J.; Stephens, J. R.

1986-01-01

Fiber reinforcements are being explored as a means to increasing the performance of superalloys past 980 C. Fiber-reinforced superalloys (FRS), particularly tungsten FRS (TFRS) are candidate materials for rocket-engine turbopump blades for advanced Shuttle engines and in airbreathing and other rocket engines. Refractory metal wires are the reinforcement of choice due to tolerance to fiber/matrix interactions. W alloy fibers have a maximum tensile strength of 2165 MPa at 1095 C and a 100 hr creep rupture strength at stresses up to 1400 MPa. A TFRS has the potential of a service temperature 110 C over the strongest superalloy. Manufacturing processes being evaluated to realize the FRS components are summarized, together with design features which will be introduced in turbine blades to take advantage of the FRS materials and to extend their surface life.

Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors

PubMed Central

Montanini, Roberto; Recupero, Antonino; De Domenico, Fabrizio; Freni, Fabrizio

2016-01-01

Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data. PMID:27669251

Creep of experimental short fiber-reinforced composite resin.

PubMed

Garoushi, Sufyan; Kaleem, Muhammad; Shinya, Akikazu; Vallittu, Pekka K; Satterthwaite, Julian D; Watts, David C; Lassila, Lippo V J

2012-01-01

The purpose of this study was to investigate the reinforcing effect of short E-glass fiber fillers oriented in different directions on composite resin under static and dynamic loading. Experimental short fiber-reinforced composite resin (FC) was prepared by mixing 22.5 wt% of short E-glass fibers, 22.5 wt% of resin, and 55 wt% of silane-treated silica fillers. Three groups of specimens (n=5) were tested: FC with isotropic fiber orientation, FC with anisotropic fiber orientation, and particulate-filled composite resin (PFC) as a control. Time-dependent creep and recovery were recorded. ANOVA revealed that after secondary curing in a vacuum oven and after storage in dry condition for 30 days, FC with isotropic fiber orientation (1.73%) exhibited significantly lower static creep value (p<0.05) than PFC (2.54%). For the different curing methods and storage conditions evaluated in this study, FC achieved acceptable static and dynamic creep values when compared to PFC.

[Preparation of carbon fiber reinforced fluid type resin denture (author's transl)].

PubMed

Kasuga, H; Sato, H; Nakabayashi, N

1980-01-01

Transverse strength of cured fluid resins is weaker than that of the heat cured. We have studied to improve the mechanical strength of self-cured acrylic resin by application of carbon fibers as reinforcement and simple methods which must be acceptable for technicians are proposed. A cloth type carbon fiber was the best reinforcement among studied carbon fibers such as chopped or mat. The chopped fibers were difficult to mix homogeneously with fluid resins and effectiveness of the reinforcement was low. Breaking often occurred at the interface between the reinforcement and resin in the cases of mat which gave defects to the test specimens. To prepare reinforced denture, the cloth was trimmed on the master cast after removal of wax and the prepreg was formed with the alginate impression on the cast by Palapress and the cloth. Other steps were same as the usual fluid resin.

Leaves Waste Composite with Glass Fiber Reinforcement

NASA Astrophysics Data System (ADS)

Khoiri, N.; Jannah, W. N.; Huda, C.; Maulana, RM; Marwoto, P.; Masturi

2018-03-01

A research has been made to fabricate leave waste composites and Polyvinyl Acetate (PvAc) polymers reinforced with glass fibers. The method used was a simple mixing of leaves powders, PvAc, and glass fibers varied from 0 g to 1 g. Mass of 16 g leaves powder and mass of PvAc 4 g. The mixing result is suppressed by 5 metric-tons for 15 minutes. The composite is dried at room temperature for 1 day then in the oven at 100°C for 1 hour. The compressive strength is measured bu a hydraulic press. The result show that the compressive strength increased to the highest point of 0.8 g and will decrease significantly when the addition of glass fiber mass of 1 g. The highest compressive strength reaches 52.6 MPa when the glass fiber mass is 0.8 g. The result of this research showed that leaves composites with Polyvinyl Acetate polymer reinforced with fiber glass can be used as alternative material of wood substitute.

Health monitoring of precast bridge deck panels reinforced with glass fiber reinforced polymer (GFRP) bars.

DOT National Transportation Integrated Search

2012-03-01

The present research project investigates monitoring concrete precast panels for bridge decks that are reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Due to the lack of long term research on concrete members reinforced with GFRP bars, lo...

Selected Bibliography on Fiber-Reinforced Cement and Concrete.

DTIC Science & Technology

1976-08-01

A listing of 660 references with author index is given for fiber reinforced cement and gypsum matrices, mortars, and concretes. Fiber types include steel, glass, plastic, asbestos, organic, carbon, and others. (Author)

In vitro study of transverse strength of fiber reinforced composites.

PubMed

Mosharraf, R; Hashemi, Z; Torkan, S

2011-01-01

Reinforcement with fiber is an effective method for considerable improvement in flexural properties of indirect composite resin restorations. The aim of this in-vitro study was to compare the transverse strength of composite resin bars reinforced with pre-impregnated and non-impregnated fibers. Thirty six bar type composite resin specimens (3×2×25 mm) were constructed in three groups. The first group was the control group (C) without any fiber reinforcement. The specimens in the second group (P) were reinforced with pre-impregnated fibers and the third group (N) with non-impregnated fibers. These specimens were tested by the three-point bending method to measure primary transverse strength. Data were statistically analyzed with one way ANOVA and Tukey's tests. There was a significant difference among the mean primary transverse strength in the three groups (P<0.001). The post-hoc (Tukey) test showed that there was a significant difference between the pre-impregnated and control groups in their primary transverse strength (P<0.001). Regarding deflection, there was also a significant difference among the three groups (P=0.001). There were significant differences among the mean deflection of the control group and two other groups (P(C&N)<.001 and P(C&P)=.004), but there was no significant difference between the non-and pre-impregnated groups (P(N&P)=.813). Within the limitations of this study, it was concluded that reinforcement with fiber considerably increased the transverse strength of composite resin specimens, but impregnation of the fiber used implemented no significant difference in the transverse strength of composite resin samples.

Arrangement for connecting a fiber-reinforced plastic pipe to a stainless steel flange

DOEpatents

Allais, Arnaud [D-30625 Hannover, DE; Hoffmann, Ernst [D-30855 Langenhagen, DE

2008-02-05

Arrangement for connecting a fiber-reinforced plastic pipe (18) to a stainless steel flange (12, 16), in which the end of the fiber-reinforced plastic pipe (18) is accommodated in a ring-shaped groove (12a, 16a) in the flange (12, 16), the groove conforming to the dimensions of the fiber-reinforced plastic pipe (18), where the gap remaining between the end of the fiber-reinforced plastic pipe (18) and the ring-shaped groove (12a, 16a) is filled with a sealant (19).

Evaluation of Glass Fiber Reinforced Concrete Panels for Use in Military Construction.

DTIC Science & Technology

1984-06-01

AD-A158 134 UNCLASSIFIED EVALUATION OF GLASS FIBER REINFORCED CONCRETE PANELS FOR USE IN MILITARY. . (U) CONSTRUCTION ENGINEERING RESEARCH LAB...Construction Engineering Research Laboratory i=h-C=iU. TECHNICAL REPORT M-85/15 June 1985 AD-A158 134 0~- 8 Evaluation of Glass Fiber ...Reinforced Concrete Panels for Use in Military Construction by Gilbert R. Williamson Glass fiber reinforced concrete (GFRC) materials are investigated

Thermo-Mechanical Fatigue of a Fiber Reinforced Titanium Aluminide Composite

DTIC Science & Technology

1991-03-01

Puiitr]on Air Foic. Base, Oiio 91 10 25 038 DTIC 4E L L E C :i<. THERMO- MECHAN I CAL FAT I GUE OF A FIBER REINFORCED TITANIUM ALUMINIDE COMPOSITE Thesis...reinforced titanium aluminide composite was investigated. Three test specimens were subjected to in-phase thermo- mechanical cycling and four to out-of...Unclassified UL ............................... AFIT/GAE/ENY/91S-1 THERMO- MECHANICAL FATIGUE OF A FIBER REINFORCED TITANIUM ALUMINIDE COMPOSITE THESIS

Experimental study on mix proportion of fiber reinforced cementitious composites

NASA Astrophysics Data System (ADS)

Jia, Yi; Zhao, Renda; Liao, Ping; Li, Fuhai; Yuan, Yuan; Zhou, Shuang

2017-10-01

To study the mechanical property of fiber reinforced cementations composites influenced by the fiber length, quartz sand diameter, matrix of water cement ratio, volume fraction of fiber and magnesium acrylate solution. Several 40×40×160 mm standard test specimens, "8" specimens and long "8" specimens and 21 groups of fiber concrete specimens were fabricated. The flexural, compressive and uniaxial tensile strength were tested by using the bending resistance, compression resistance and electronic universal testing machine. The results show that flexural and compressive strength of fiber reinforced cementations composites increases along with the increase of quartz sand diameter, with the growth of the PVA fiber length increases; When the water-binder ratio is 0.25 and powder-binder ratio is 0.3, the PVA fiber content is 1.5% of the mass of cementations materials, there is a phenomenon of strain hardening; The addition of magnesium acrylate solution reduces the tensile strength of PVA fiber reinforced cementations composites, the tensile strength of the specimens in the curing age of 7d is decreased by about 21% and the specimens in curing age of 28d is decreased by more than 50%.

Molecular Dynamics Modeling of PPTA Crystals in Aramid Fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mercer, Brian Scott

2016-05-19

In this work, molecular dynamics modeling is used to study the mechanical properties of PPTA crystallites, which are the fundamental microstructural building blocks of polymer aramid bers such as Kevlar. Particular focus is given to constant strain rate axial loading simulations of PPTA crystallites, which is motivated by the rate-dependent mechanical properties observed in some experiments with aramid bers. In order to accommodate the covalent bond rupture that occurs in loading a crystallite to failure, the reactive bond order force eld ReaxFF is employed to conduct the simulations. Two major topics are addressed: The rst is the general behavior ofmore » PPTA crystallites under strain rate loading. Constant strain rate loading simulations of crystalline PPTA reveal that the crystal failure strain increases with increasing strain rate, while the modulus is not a ected by the strain rate. Increasing temperature lowers both the modulus and the failure strain. The simulations also identify the C N bond connecting the aromatic rings as weakest primary bond along the backbone of the PPTA chain. The e ect of chain-end defects on PPTA micromechanics is explored, and it is found that the presence of a chain-end defect transfers load to the adjacent chains in the hydrogen-bonded sheet in which the defect resides, but does not in uence the behavior of any other chains in the crystal. Chain-end defects are found to lower the strength of the crystal when clustered together, inducing bond failure via stress concentrations arising from the load transfer to bonds in adjacent chains near the defect site. The second topic addressed is the nature of primary and secondary bond failure in crystalline PPTA. Failure of both types of bonds is found to be stochastic in nature and driven by thermal uctuations of the bonds within the crystal. A model is proposed which uses reliability theory to model bonds under constant strain rate loading as components with time-dependent failure rate

Effect of PVA fiber content on creep property of fiber reinforced high-strength concrete columns

NASA Astrophysics Data System (ADS)

Xu, Zongnan; Wang, Tao; Wang, Weilun

2018-04-01

The effect of PVA (polyvinyl alcohol) fiber content on the creep property of fiber reinforced high-strength concrete columns was investigated. The correction factor of PVA fiber content was proposed and the creep prediction model of ACI209 was modified. Controlling the concrete strength as C80, changing the content of PVA fiber (volume fraction 0%, 0.25%, 0.5%, 1% respectively), the creep experiment of PVA fiber reinforced concrete columns was carried out, the creep coefficient of each specimen was calculated to characterize the creep property. The influence of PVA fiber content on the creep property was analyzed based on the creep coefficient and the calculation results of several frequently used creep prediction models. The correction factor of PVA fiber content was proposed to modify the ACI209 creep prediction model.

Durability of Waste Glass Flax Fiber Reinforced Mortar

NASA Astrophysics Data System (ADS)

Aly, M.; Hashmi, M. S. J.; Olabi, A. G.; Messeiry, M.

2011-01-01

The main concern for natural fibre reinforced mortar composites is the durability of the fibres in the alkaline environment of cement. The composites may undergo a reduction in strength as a result of weakening of the fibres by a combination of alkali attack and fibre mineralisation. In order to enhance the durability of natural fiber reinforced cement composites several approaches have been studied including fiber impregnation, sealing of the matrix pore system and reduction of matrix alkalinity through the use of pozzolanic materials. In this study waste glass powder was used as a pozzolanic additive to improve the durability performance of flax fiber reinforced mortar (FFRM). The durability of the FFRM was studied by determining the effects of ageing in water and exposure to wetting and drying cycles; on the microstructures and flexural behaviour of the composites. The mortar tests demonstrated that the waste glass powder has significant effect on improving the durability of FFRM.

Durability of waste glass flax fiber reinforced mortar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aly, M.; Hashmi, M. S. J.; Olabi, A. G.

2011-01-17

The main concern for natural fibre reinforced mortar composites is the durability of the fibres in the alkaline environment of cement. The composites may undergo a reduction in strength as a result of weakening of the fibres by a combination of alkali attack and fibre mineralisation. In order to enhance the durability of natural fiber reinforced cement composites several approaches have been studied including fiber impregnation, sealing of the matrix pore system and reduction of matrix alkalinity through the use of pozzolanic materials. In this study waste glass powder was used as a pozzolanic additive to improve the durability performancemore » of flax fiber reinforced mortar (FFRM). The durability of the FFRM was studied by determining the effects of ageing in water and exposure to wetting and drying cycles; on the microstructures and flexural behaviour of the composites. The mortar tests demonstrated that the waste glass powder has significant effect on improving the durability of FFRM.« less

Non-destructive testing on aramid fibres for the long-term assessment of interventions on heritage structures

NASA Astrophysics Data System (ADS)

Ceravolo, R.; De Marchi, A.; Pinotti, E.; Surace, C.; Zanotti Fragonara, L.

2015-07-01

High strength fibre reinforced polymers (FRPs) are composite materials made of fibres such as carbon, aramid and/or glass, and a resin matrix. FRPs are commonly used for structural repair and strengthening interventions and exhibit high potential for applications to existing constructions, including heritage buildings. In regard to aramid fibres, uncertainties about the long-term behaviour of these materials have often made the designers reluctant to use them in structural engineering. The present study describes simple and non-destructive nonlinearity tests for assessing damage or degradation of structural properties in Kevlar fibres. This was obtained by using high precision measurements to detect small deviations in the dynamic response measured on fibres and ropes. The change in dynamic properties was then related to a damage produced by exposure of the sample to UV rays for a defined time period, which simulated long-term sun exposure. In order to investigate the sensitivity of such an approach to damage detection, non-linearity characterisation tests were conducted on aramid fibres in both damaged and undamaged states. With the purpose of carrying out dynamic tests on small fibre specimens, a dedicated instrumentation was designed and built in cooperation with the Metrology Laboratory of the Department of Electronics at the Politecnico di Torino.

Method of making carbon fiber-carbon matrix reinforced ceramic composites

NASA Technical Reports Server (NTRS)

Williams, Brian (Inventor); Benander, Robert (Inventor)

2007-01-01

A method of making a carbon fiber-carbon matrix reinforced ceramic composite wherein the result is a carbon fiber-carbon matrix reinforcement is embedded within a ceramic matrix. The ceramic matrix does not penetrate into the carbon fiber-carbon matrix reinforcement to any significant degree. The carbide matrix is a formed in situ solid carbide of at least one metal having a melting point above about 1850 degrees centigrade. At least when the composite is intended to operate between approximately 1500 and 2000 degrees centigrade for extended periods of time the solid carbide with the embedded reinforcement is formed first by reaction infiltration. Molten silicon is then diffused into the carbide. The molten silicon diffuses preferentially into the carbide matrix but not to any significant degree into the carbon-carbon reinforcement. Where the composite is intended to operate between approximately 2000 and 2700 degrees centigrade for extended periods of time such diffusion of molten silicon into the carbide is optional and generally preferred, but not essential.

Properties of discontinuous S2-glass fiber-particulate-reinforced resin composites with two different fiber length distributions.

PubMed

Huang, Qiting; Garoushi, Sufyan; Lin, Zhengmei; He, Jingwei; Qin, Wei; Liu, Fang; Vallittu, Pekka Kalevi; Lassila, Lippo Veli Juhana

2017-10-01

To investigate the reinforcing efficiency and light curing properties of discontinuous S2-glass fiber-particulate reinforced resin composite and to examine length distribution of discontinuous S2-glass fibers after a mixing process into resin composite. Experimental S2-glass fiber-particulate reinforced resin composites were prepared by mixing 10wt% of discontinuous S2-glass fibers, which had been manually cut into two different lengths (1.5 and 3.0mm), with various weight ratios of dimethacrylate based resin matrix and silaned BaAlSiO 2 filler particulates. The resin composite made with 25wt% of UDMA/SR833s resin system and 75wt% of silaned BaAlSiO 2 filler particulates was used as control composite which had similar composition as the commonly used resin composites. Flexural strength (FS), flexural modulus (FM) and work of fracture (WOF) were measured. Fractured specimens were observed by scanning electron microscopy. Double bond conversion (DC) and fiber length distribution were also studied. Reinforcement of resin composites with discontinuous S2-glass fibers can significantly increase the FS, FM and WOF of resin composites over the control. The fibers from the mixed resin composites showed great variation in final fiber length. The mean aspect ratio of experimental composites containing 62.5wt% of particulate fillers and 10wt% of 1.5 or 3.0mm cutting S2-glass fibers was 70 and 132, respectively. No difference was found in DC between resin composites containing S2-glass fibers with two different cutting lengths. Discontinuous S2-glass fibers can effectively reinforce the particulate-filled resin composite and thus may be potential to manufacture resin composites for high-stress bearing application. Copyright © 2017. Published by Elsevier Ltd.

Multifunctional fiber reinforced polymer composites using carbon and boron nitride nanotubes

NASA Astrophysics Data System (ADS)

Ashrafi, Behnam; Jakubinek, Michael B.; Martinez-Rubi, Yadienka; Rahmat, Meysam; Djokic, Drazen; Laqua, Kurtis; Park, Daesun; Kim, Keun-Su; Simard, Benoit; Yousefpour, Ali

2017-12-01

Recent progress in nanotechnology has made several nano-based materials available with the potential to address limitations of conventional fiber reinforced polymer composites, particularly in reference to multifunctional structures. Carbon nanotubes (CNTs) are the most prevalent case and offer amazing properties at the individual nanotube level. There are already a few high-profile examples of the use of CNTs in space structures to provide added electrical conductivity for static dissipation and electromagnetic shielding. Boron nitride nanotubes (BNNTs), which are structurally analogous to CNTs, also present a range of attractive properties. Like the more widely explored CNTs, individual BNNTs display remarkable mechanical properties and high thermal conductivity but with contrasting functional attributes including substantially higher thermal stability, high electrical insulation, polarizability, high neutron absorption and transparency to visible light. This presents the potential of employing either or both BNNTs and CNTs to achieve a range of lightweight, functional composites for space structures. Here we present the case for application of BNNTs, in addition to CNTs, in space structures and describe recent advances in BNNT production at the National Research Council Canada (NRC) that have, for the first time, provided sufficiently large quantities to enable commercialization of high-quality BNNTs and accelerate development of chemistry, composites and applications based on BNNTs. Early demonstrations showing the fabrication and limited structural testing of polymer matrix composites, including glass fiber-reinforced composite panels containing BNNTs will be discussed.

Performance of steel wool fiber reinforced geopolymer concrete

NASA Astrophysics Data System (ADS)

Faris, Meor Ahmad; Abdullah, Mohd Mustafa Al Bakri; Ismail, Khairul Nizar; Muniandy, Ratnasamy; Ariffin, Nurliayana

2017-09-01

In this paper, performance of geopolymer concrete was studied by mixing of Class F fly ash from Manjung power station, Lumut, Perak, Malaysia with alkaline activator which are combination of sodium hydroxide and sodium silicate. Steel wool fiber were added into the geopolymer concrete as reinforcement with different weight percentage vary from 0 % - 5 %. Chemical compositions of Malaysian fly ash was first analyzed by using X-ray fluorescence. All geopolymer concrete reinforced with steel wool fiber with different weight percentage were tested in terms of density, workability, and compression. Result shows Malaysian fly ash identified by using XRF was class F. Density of geopolymer concrete close to density of OPC which is approximately 2400 kg/m3 and the density was increase gradually with the additions of steel fiber. However, the inclusions of steel fibers also shows some reduction to the workability of geopolymer concrete. Besides, the compressive strength was increased with the increasing of fibers addition until maximum of 18.6 % improvement at 3 % of steel fibers.

Development of ductile hybrid fiber reinforced polymer (D-H-FRP) reinforcement for concrete structures

NASA Astrophysics Data System (ADS)

Somboonsong, Win

The corrosion of steel rebars has been the major cause of the reinforced concrete deterioration in transportation structures and port facilities. Currently, the Federal Highway Administration (FHWA) spends annually $31 billion for maintaining and repairing highways and highway bridges. The study reported herein represents the work done in developing a new type of reinforcement called Ductile Hybrid Fiber Reinforced Polymer or D-H-FRP using non-corrosive fiber materials. Unlike the previous FRP reinforcements that fail in a brittle manner, the D-H-FRP bars exhibit the stress-strain curves that are suitable for concrete reinforcement. The D-H-FRP stress-strain curves are linearly elastic with a definite yield point followed by plastic deformation and strain hardening resembling that of mild steel. In addition, the D-H-FRP reinforcement has integrated ribs required for concrete bond. The desirable mechanical properties of D-H-FRP reinforcement are obtained from the integrated design based on the material hybrid and geometric hybrid concepts. Using these concepts, the properties can be tailored to meet the specific design requirements. An analytical model was developed to predict the D-H-FRP stress-strain curves with different combination of fiber materials and geometric configuration. This model was used to optimize the design of D-H-FRP bars. An in-line braiding-pultrusion manufacturing process was developed at Drexel University to produce high quality D-H-FRP reinforcement in diameters that can be used in concrete structures. A series of experiments were carried out to test D-H-FRP reinforcement as well as their individual components in monotonic and cyclic tensile tests. Using the results from the tensile tests and fracture analysis, the stress-strain behavior of the D-H-FRP reinforcement was fully characterized and explained. Two series of concrete beams reinforced with D-H-FRP bars were studied. The D-H-FRP beam test results were then compared with companion

Effect of fiber content on flexural properties of glass fiber-reinforced polyamide-6 prepared by injection molding.

PubMed

Nagakura, Manamu; Tanimoto, Yasuhiro; Nishiyama, Norihiro

2017-07-26

The use of non-metal clasp denture (NMCD) materials may seriously affect the remaining tissues because of the low rigidity of NMCD materials such as polyamides. The purpose of this study was to develop a high-rigidity glass fiber-reinforced thermoplastic (GFRTP) composed of E-glass fiber and polyamide-6 for NMCDs using an injection molding. The reinforcing effects of fiber on the flexural properties of GFRTPs were investigated using glass fiber content ranging from 0 to 50 mass%. Three-point bending tests indicated that the flexural strength and elastic modulus of a GFRTP with a fiber content of 50 mass% were 5.4 and 4.7 times higher than those of unreinforced polyamide-6, respectively. The result showed that the physical characteristics of GFRTPs were greatly improved by increasing the fiber content, and the beneficial effects of fiber reinforcement were evident. The findings suggest that the injection-molded GFRTPs are adaptable to NMCDs because of their excellent mechanical properties.

Room-temperature aqueous plasma electrolyzing Al2O3 nano-coating on carbon fiber

NASA Astrophysics Data System (ADS)

Zhang, Yuping; Meng, Yang; Shen, Yonghua; Chen, Weiwei; Cheng, Huanwu; Wang, Lu

2017-10-01

A novel room-temperature aqueous plasma electrolysis technique has been developed in order to prepared Al2O3 nano-coating on each fiber within a carbon fiber bundle. The microstructure and formation mechanism of the Al2O3 nano-coating were systematically investigated. The oxidation resistance and tensile strength of the Al2O3-coated carbon fiber was measured at elevated temperatures. It showed that the dense Al2O3 nano-coating was relatively uniformly deposited with 80-120 nm in thickness. The Al2O3 nano-coating effectively protected the carbon fiber, evidenced by the slower oxidation rate and significant increase of the burn-out temperature from 800 °C to 950 °C. Although the bare carbon fiber remained ∼25 wt.% after oxidation at 700 °C for 20 min, a full destruction was observed, evidenced by the ∼0 GPa of the tensile strength, compared to ∼1.3 GPa of the Al2O3-coated carbon fiber due to the effective protection from the Al2O3 nano-coating. The formation mechanism of the Al2O3 nano-coating on carbon fiber was schematically established mainly based on the physic-chemical effect in the cathodic plasma arc zone.

Preliminary evaluation of fiber composite reinforcement of truck frame rails

NASA Technical Reports Server (NTRS)

Faddoul, J. R.

1977-01-01

The use of graphite fiber/resin matrix composite to effectively reinforce a standard steel truck frame rail is studied. A preliminary design was made and it was determined that the reinforcement weight could be reduced by a factor of 10 when compared to a steel reinforcement. A section of a 1/3 scale reinforced rail was fabricated to demonstrate low cost manufacturing techniques. The scale rail section was then tested and increased stiffness was confirmed. No evidence of composite fatigue was found after 500,000 cycles to a fiber stress of 34,000 psi. The test specimen failed in bending in a static test at a load 50 percent greater than that predicted for a non-reinforced rail.

Primary Manufacturing Processes for Fiber Reinforced Composites: History, Development & Future Research Trends

NASA Astrophysics Data System (ADS)

Tapan Bhatt, Alpa; Gohil, Piyush P.; Chaudhary, Vijaykumar

2018-03-01

Composite Materials are becoming more popular gradually replacing traditional material with extra strength, lighter weight and superior property. The world is exploring use of fiber reinforced composites in all application which includes air, land and water transport, construction industry, toys, instrumentation, medicine and the list is endless. Based on application and reinforcement used, there are many ways to manufactures parts with fiber reinforced composites. In this paper various manufacturing processes have been discussed at length, to make fiber reinforced composites components. The authors have endeavored to include all the processes available recently in composite industry. Paper first highlights history of fiber reinforced composites manufacturing, and then the comparison of different manufacturing process to build composites have been discussed, to give clear understanding on, which process should be selected, based on reinforcement, matrix and application. All though, there are several advantages to use such fiber reinforcement composites, still industries have not grown at par and there is a lot of scope to improve these industries. At last, where India stands today, what are the challenges in market has been highlighted and future market and research trend of exploring such composite industries have been discussed. This work is carried out as a part of research project sanctioned by GUJCOST, Gandhinagar.

The recycling of comminuted glass-fiber-reinforced resin from electronic waste.

PubMed

Duan, Huabo; Jia, Weifeng; Li, Jinhui

2010-05-01

The reuse of comminuted glass-fiber-reinforced resin with various granularities gathered from printed circuit manufacturing residues was investigated. As fillers, these residues were converted into polymeric composite board by an extrusion and injection process using polypropylene as a bonding agent. The mechanical properties of the reproduced composite board were examined by considering the effects of mass fraction and glass-fiber distribution. Interfacial-layer micrograph analysis of the composite material fracture surface was used to study the fiber reinforcement mechanism. Results showed that using comminuted glass-fiber-reinforced resin as a filler material greatly enhanced the performance properties of the composite board. Although the length and diameter of filler varied, these variations had no appreciable effect on the mechanical properties of the processed board. Maximum values of 48.30 MPa for flexural strength, 31.34 MPa for tensile strength, and 31.34 J/m for impact strength were achieved from a composite board containing mass fractions of 30, 10, and 20% glass-fiber-reinforced resin waste, respectively. It was found that the maximum amount of recyclate that could be added to a composite board was 30% of weight. Beyond these percentages, the materials blend became unmanageable and the mixture less amenable to impregnation with fiber. Presented studies indicated that comminuted glass-fiber-reinforced resin waste-filled polypropylene composites are promising candidates for structural applications where high stiffness and fracture resistance are required.

Mechanical Behavior of Stainless Steel Fiber-Reinforced Composites Exposed to Accelerated Corrosion

PubMed Central

O’Brien, Caitlin; McBride, Amanda; E. Zaghi, Arash; Burke, Kelly A.; Hill, Alex

2017-01-01

Recent advancements in metal fibers have introduced a promising new type of stainless steel fiber with high stiffness, high failure strain, and a thickness < 100 μm (<0.00394 in.) that can be utilized in a steel fiber-reinforced polymer. However, stainless steel is known to be susceptible to pitting corrosion. The main goal of this study is to compare the impact of corrosion on the mechanical properties of steel fiber-reinforced composites with those of conventional types of stainless steel. By providing experimental evidences, this study may promote the application of steel fiber-reinforced composite as a viable alternative to conventional metals. Samples of steel fiber-reinforced polymer and four different types of stainless steel were subjected to 144 and 288 h of corrosion in ferric chloride solution to simulate accelerated corrosion conditions. The weight losses due to corrosion were recorded. The corroded and control samples were tested under monotonic tensile loading to measure the ultimate stresses and strains. The effect of corrosion on the mechanical properties of the different materials was evaluated. The digital image correlation (DIC) technique was used to investigate the failure mechanism of the corrosion-damaged specimens. Overall, steel fiber-reinforced composites had the greatest corrosion resistance. PMID:28773132

Fiber reinforced superalloys

NASA Technical Reports Server (NTRS)

Petrasek, Donald W.; Signorelli, Robert A.; Caulfield, Thomas; Tien, John K.

1987-01-01

Improved performance of heat engines is largely dependent upon maximum cycle temperatures. Tungsten fiber reinforced superalloys (TFRS) are the first of a family of high temperature composites that offer the potential for significantly raising hot component operating temperatures and thus leading to improved heat engine performance. This status review of TFRS research emphasizes the promising property data developed to date, the status of TFRS composite airfoil fabrication technology, and the areas requiring more attention to assure their applicability to hot section components of aircraft gas turbine engines.

Graphite coated PVA fibers as the reinforcement for cementitious composites

NASA Astrophysics Data System (ADS)

Zhang, Yunhua; Zhang, Zhipeng; Liu, Zhichao

2018-02-01

A new preconditioning method was developed to PVA fibers as the reinforcement in cement-based materials. Virgin PVA fibers exhibits limited adhesion to graphite powders due to the presence of oil spots on the surface. Mixing PVA fibers with a moderately concentrated KMnO4-H2SO4 solution can efficiently remove the oil spots by oxidation without creating extra precipitate (MnO2) associated with the reduction reaction. This enhances the coating of graphite powders onto fiber surface and improves the mechanical properties of PVA fiber reinforced concrete (PVA-FRC). Graphite powders yields better fiber distribution in the matrix and reduces the fiber-matrix bonding, which is beneficial in uniformly distributing the stress among embedded fibers and creating steady generation and propagation of tight microcracks. This is evidenced by the significantly enhanced strain hardening behavior and improved flexural strength and toughness.

Effect of fiber diameter on flexural properties of fiber-reinforced composites.

PubMed

Rezvani, Mohammad Bagher; Atai, Mohammad; Hamze, Faeze

2013-01-01

Flexural strength (FS) is one of the most important properties of restorative dental materials which could be improved in fiber-reinforced composites (FRCs) by several methods including the incorporation of stronger reinforcing fibers. This study evaluates the influence of the glass fiber diameter on the FS and elastic modulus of FRCs at the same weight percentage. A mixture of 2,2-bis-[4-(methacryloxypropoxy)-phenyl]-propaneand triethyleneglycol dimethacrylate (60/40 by weight) was prepared as the matrix phase in which 0.5 wt. % camphorquinone and 0.5 wt. % N-N'-dimethylaminoethyl methacrylate were dissolved as photoinitiator system. Glass fibers with three different diameters (14, 19, and 26 μm) were impregnated with the matrix resin using a soft brush. The FRCs were inserted into a 2 × 2 × 25 mm3 mold and cured using a light curing unit with an intensity of ca. 600 mW/cm2 . The FS of the FRCs was measured in a three-point bending method. The elastic modulus was determined from the slope of the initial linear part of stress-strain curve. The fracture surface of the composites was observed using scanning electron microscopy to study the fiber-matrix interface. The results were analyzed and compared using one-way ANOVA and Tukey's post-hoc test. Although the FS increased as the diameter of fibers increased up to 19 μm (P < 0.05), no significant difference was observed between the composites containing fibers with diameters of 19 and 26 μm. The diameter of the fibers influences the mechanical properties of the FRCs.

Assessment of the mechanical properties of sisal fiber-reinforced silty clay using triaxial shear tests.

PubMed

Wu, Yankai; Li, Yanbin; Niu, Bin

2014-01-01

Fiber reinforcement is widely used in construction engineering to improve the mechanical properties of soil because it increases the soil's strength and improves the soil's mechanical properties. However, the mechanical properties of fiber-reinforced soils remain controversial. The present study investigated the mechanical properties of silty clay reinforced with discrete, randomly distributed sisal fibers using triaxial shear tests. The sisal fibers were cut to different lengths, randomly mixed with silty clay in varying percentages, and compacted to the maximum dry density at the optimum moisture content. The results indicate that with a fiber length of 10 mm and content of 1.0%, sisal fiber-reinforced silty clay is 20% stronger than nonreinforced silty clay. The fiber-reinforced silty clay exhibited crack fracture and surface shear fracture failure modes, implying that sisal fiber is a good earth reinforcement material with potential applications in civil engineering, dam foundation, roadbed engineering, and ground treatment.

Assessment of the Mechanical Properties of Sisal Fiber-Reinforced Silty Clay Using Triaxial Shear Tests

PubMed Central

Wu, Yankai; Li, Yanbin; Niu, Bin

2014-01-01

Fiber reinforcement is widely used in construction engineering to improve the mechanical properties of soil because it increases the soil's strength and improves the soil's mechanical properties. However, the mechanical properties of fiber-reinforced soils remain controversial. The present study investigated the mechanical properties of silty clay reinforced with discrete, randomly distributed sisal fibers using triaxial shear tests. The sisal fibers were cut to different lengths, randomly mixed with silty clay in varying percentages, and compacted to the maximum dry density at the optimum moisture content. The results indicate that with a fiber length of 10 mm and content of 1.0%, sisal fiber-reinforced silty clay is 20% stronger than nonreinforced silty clay. The fiber-reinforced silty clay exhibited crack fracture and surface shear fracture failure modes, implying that sisal fiber is a good earth reinforcement material with potential applications in civil engineering, dam foundation, roadbed engineering, and ground treatment. PMID:24982951

Preparation of tungsten fiber reinforced-tungsten/copper composite for plasma facing component

NASA Astrophysics Data System (ADS)

He, Gang; Xu, Kunyuan; Guo, Shibin; Qian, Xueqiang; Yang, Zengchao; Liu, Guanghua; Li, Jiangtao

2014-12-01

W fiber reinforced-W/Cu composite is designed as a transition layer between CuCrZr heat sink material and W plasma facing material. A novel method was developed for the preparation of W fiber reinforced-W/Cu composite by combining combustion synthesis with centrifugal infiltration. Cu melt with a transient temperature over 2000 °C produced by the thermite reaction was infiltrated into the W powder and fiber bed with the assistance of a high gravity field. It was found that the W particles were sintered and bonded to the W fibers due to the high temperature produced by the thermite reaction. The bending strength of W/Cu composite improved 12.7% through W fibers reinforcement.

Effect of hot-dry environment on fiber-reinforced self-compacting concrete

NASA Astrophysics Data System (ADS)

Tioua, Tahar; Kriker, Abdelouahed; Salhi, Aimad; Barluenga, Gonzalo

2016-07-01

Drying shrinkage can be a major reason for the deterioration of concrete structures. Variation in ambient temperature and relative humidity cause changes in the properties of hardened concrete which can affect their mechanical and drying shrinkage characteristics. The present study investigated mechanical strength and particularly drying shrinkage properties of self-compacting concretes (SCC) reinforced with date palm fiber exposed to hot and dry environment. In this study a total of nine different fibers reinforced self compacting concrete (FRSCC) mixtures and one mixture without fiber were prepared. The volume fraction and the length of fibers reinforcement were 0.1-0.2-0.3% and 10-20-30 mm. It was observed that drying shrinkage lessened with adding low volumetric fraction and short length of fibers in curing condition (T = 20 °C and RH = 50 ± 5 %), but increased in hot and dry environment.

Method of producing a ceramic fiber-reinforced glass-ceramic matrix composite

NASA Technical Reports Server (NTRS)

Bansal, Narottam P. (Inventor)

1994-01-01

A fiber-reinforced composite composed of a BaO-Al2O3-2SiO2 (BAS) glass ceramic matrix is reinforced with CVD silicon carbide continuous fibers. A slurry of BAS glass powders is prepared and celsian seeds are added during ball melting. The slurry is cast into tapes which are cut to the proper size. Continuous CVD-SiC fibers are formed into mats of the desired size. The matrix tapes and the fiber mats are alternately stacked in the proper orientation. This tape-mat stack is warm pressed to produce a 'green' composite. The 'green' composite is then heated to an elevated temperature to burn out organic constituents. The remaining interim material is then hot pressed to form a silicon carbide fiber-reinforced celsian (BAS) glass-ceramic matrix composite which may be machined to size.

Effect of fiber fibrillation on impact and flexural strength of coir fiber reinforced epoxy hybrid composites

NASA Astrophysics Data System (ADS)

Mawardi, I.; Jufriadi; Hanif

2018-03-01

This study aims to develop fiber-reinforced epoxy resin composites. This study presents the effect of fiber fibrillation on the impact and flextural strength of the epoxy hybrid composite reinforced by coir fiber. Coir is soaked in 5% NaOH solution for 5 hours. Then fiber is rocessed using a blender of 2000 rpm density fibrillation. The length of time the fibrillation varied for 10, 20 and 30 minutes. Volume fraction of 30% fiber and matrix 70% composited. The composite uses a matrix of epoxy by hand lay up method. The implemented tests are impact and flexural tests. The test results show fiber fibrillation treatment can improve the composite mechanical properties. The highest impact and flexural strength, 24.45 kJ/m2 and 87.91 MPa were produced with fiber fibrillation for 10 minutes.

Moment redistribution in continuous reinforced concrete beams strengthened with carbon-fiber-reinforced polymer laminates

NASA Astrophysics Data System (ADS)

Aiello, M. A.; Valente, L.; Rizzo, A.

2007-09-01

The results of tests on continuous steel-fiber-reinforced concrete (RC) beams, with and without an external strengthening, are presented. The internal flexural steel reinforcement was designed so that to allow steel yielding before the collapse of the beams. To prevent the shear failure, steel stirrups were used. The tests also included two nonstrengthened control beams; the other specimens were strengthened with different configurations of externally bonded carbon-fiber-reinforced polymer (CFRP) laminates. In order to prevent the premature failure from delamination of the CFRP strengthening, a wrapping was also applied. The experimental results obtained show that it is possible to achieve a sufficient degree of moment redistribution if the strengthening configuration is chosen properly, confirming the results provided by two simple numerical models.

Basalt fiber reinforced polymer composites: Processing and properties

NASA Astrophysics Data System (ADS)

Liu, Qiang

A high efficiency rig was designed and built for in-plane permeability measurement of fabric materials. A new data derivation procedure to acquire the flow fluid pattern in the experiment was developed. The measurement results of the in-plane permeability for basalt twill 31 fabric material showed that a high correlation exists between the two principal permeability values for this fabric at 35% fiber volume fraction. This may be the most important scientific contribution made in this thesis. The results from radial measurements corresponded quite well with those from Unidirectional (UD) measurements, which is a well-established technique. No significant differences in mechanical properties were found between basalt fabric reinforced polymer composites and glass composites reinforced by a fabric of similar weave pattern. Aging results indicate that the interfacial region in basalt composites may be more vulnerable to environmental damage than that in glass composites. However, the basalt/epoxy interface may have been more durable than the glass/epoxy interface in tension-tension fatigue because the basalt composites have significantly longer fatigue life. In this thesis, chapter I reviews the literature on fiber reinforced polymer composites, with concentration on permeability measurement, mechanical properties and durability. Chapter II discusses the design of the new rig for in-plane permeability measurement, the new derivation procedure for monitoring of the fluid flow pattern, and the permeability measurement results. Chapter III compares the mechanical properties and durability between basalt fiber and glass fiber reinforced polymer composites. Lastly, chapter IV gives some suggestions and recommendations for future work.

Experimental and numerical characterization of scalable cellulose nano-fiber composite

NASA Astrophysics Data System (ADS)

Barari, Bamdad

Fiber-reinforced polymer composites have been used in recent years as an alternative to the conventional materials because of their low weight, high mechanical properties and low processing temperatures. Most polymer composites are traditionally made using reinforcing fibers such as carbon or glass fibers. However, there has been recent interest in making these reinforcing fibers from natural resources. The plant-derived cellulose nano-fibers (CNF) are a material with remarkable mechanical properties at the nano-scale that are much superior to the mechanical properties of the traditional natural fibers (such as jute, hemp, kenaf, etc) used in the natural-fiber based polymer composites. Because CNF is bio-based and biodegradable, it is an attractive 'green' alternative for use in automotive, aerospace, and other engineering applications. However, efforts to produce CNF based nano-composites, with successful scaling-up of the remarkable nanoscale properties of CNF, have not met with much success and form an active area of research. The main goals of this research are to characterize the scalable CNF based nano composites using experimental methods and to develop effective models for flow of polymeric resin in the CNF-based porous media used during the proposed manufacture of CNF nano-composites. In the CNF composite characterization section, scalable isotropic and anisotropic CNF composites were made from a porous CNF preforms created using a freeze drying process. Formation of the fibers during freeze-drying process can change the micro skeleton of the final preform structure as non-aligned or isotropic and aligned or anisotropic CNF. Liquid Composite Molding (LCM) processes form a set of liquid molding technologies that are used quite commonly for making the conventional polymer composites. An improvised vacuum-driven LCM process was used to make the CNF-based nanocomposites from CNF preforms using a 'green' epoxy resin with high bio-content. Under the topic of

Performance of a bridge deck with glass fiber reinforced polymer bars as the top mat of reinforcement.

DOT National Transportation Integrated Search

2005-01-01

The purpose of this research was to investigate the performance of glass fiber reinforced polymer (GFRP) bars as reinforcement for concrete decks. Today's rapid bridge deck deterioration is calling for a replacement for steel reinforcement. The advan...

Natural Kenaf Fiber Reinforced Composites as Engineered Structural Materials

NASA Astrophysics Data System (ADS)

Dittenber, David B.

The objective of this work was to provide a comprehensive evaluation of natural fiber reinforced polymer (NFRP)'s ability to act as a structural material. As a chemical treatment, aligned kenaf fibers were treated with sodium hydroxide (alkalization) in different concentrations and durations and then manufactured into kenaf fiber / vinyl ester composite plates. Single fiber tensile properties and composite flexural properties, both in dry and saturated environments, were assessed. Based on ASTM standard testing, a comparison of flexural, tensile, compressive, and shear mechanical properties was also made between an untreated kenaf fiber reinforced composite, a chemically treated kenaf fiber reinforced composite, a glass fiber reinforced composite, and oriented strand board (OSB). The mechanical properties were evaluated for dry samples, samples immersed in water for 50 hours, and samples immersed in water until saturation (~2700 hours). Since NFRPs are more vulnerable to environmental effects than synthetic fiber composites, a series of weathering and environmental tests were conducted on the kenaf fiber composites. The environmental conditions studied include real-time outdoor weathering, elevated temperatures, immersion in different pH solutions, and UV exposure. In all of these tests, degradation was found to be more pronounced in the NFRPs than in the glass FRPs; however, in nearly every case the degradation was less than 50% of the flexural strength or stiffness. Using a method of overlapping and meshing discontinuous fiber ends, large mats of fiber bundles were manufactured into composite facesheets for structural insulated panels (SIPs). The polyisocyanurate foam cores proved to be poorly matched to the strength and stiffness of the NFRP facesheets, leading to premature core shear or delamination failures in both flexure and compressive testing. The NFRPs were found to match well with the theoretical stiffness prediction methods of classical lamination

Load-bearing capacity of human incisor restored with various fiber-reinforced composite posts.

PubMed

Le Bell-Rönnlöf, Anna-Maria; Lassila, Lippo V J; Kangasniemi, Ilkka; Vallittu, Pekka K

2011-06-01

The aim of this study was to evaluate the load-bearing capacity and microstrain of incisors restored with posts of various kinds. Both prefabricated titanium posts and different fiber-reinforced composite posts were tested. The crowns of human incisors were cut and post preparation was carried out. The roots were divided into groups: (1) prefabricated serrated titanium posts, (2) prefabricated carbon fiber-reinforced composite posts, (3) individually formed glass fiber-reinforced composite posts with the canal full of fibers, and (4) individually formed "split" glass fiber-reinforced composite posts. The posts were cemented and composite crowns were made. Intact human incisors were used as reference. All roots were embedded in acrylic resin cylinders and stored at room temperature in water. Static load was applied under a loading angle of 45° using a universal testing machine. On half of the specimens microstrain was measured with strain gages and an acoustic emission analysis was carried out. Failure mode assessment was also made. The group with titanium posts showed highest number of unfavorable failures compared to the groups with fiber-reinforced composite posts. With fiber-reinforced composite posts the failures may more often be favorable compared to titanium posts, which clinically means repairable failures. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Removing Pathogens Using Nano-Ceramic-Fiber Filters

NASA Technical Reports Server (NTRS)

Tepper, Frederick; Kaledin, Leonid

2005-01-01

A nano-aluminum-oxide fiber of only 2 nanometers in diameter was used to develop a ceramic-fiber filter. The fibers are electropositive and, when formulated into a filter material (NanoCeram(TradeMark)), would attract electro-negative particles such as bacteria and viruses. The ability to detect and then remove viruses as well as bacteria is of concern in space cabins since they may be carried onboard by space crews. Moreover, an improved filter was desired that would polish the effluent from condensed moisture and wastewater, producing potable drinking water. A laboratory- size filter was developed that was capable of removing greater than 99.9999 percent of bacteria and virus. Such a removal was achieved at flow rates hundreds of times greater than those through ultraporous membranes that remove particles by sieving. Because the pore size of the new filter was rather large as compared to ultraporous membranes, it was found to be more resistant to clogging. Additionally, a full-size cartridge is being developed that is capable of serving a full space crew. During this ongoing effort, research demonstrated that the filter media was a very efficient adsorbent for DNA (deoxyribonucleic acid), RNA (ribonucleic acid), and endotoxins. Since the adsorption is based on the charge of the macromolecules, there is also a potential for separating proteins and other particulates on the basis of their charge differences. The separation of specific proteins is a major new thrust of biotechnology. The principal application of NanoCeram filters is based on their ability to remove viruses from water. The removal of more than 99.9999 percent of viruses was achieved by a NanoCeram polishing filter added to the effluent of an existing filtration device. NanoCeram is commercially available in laboratory-size filter discs and in the form of a syringe filter. The unique characteristic of the filter can be demonstrated by its ability to remove particulate dyes such as Metanyl yellow. Its

Elastic properties of uniaxial-fiber reinforced composites - General features

NASA Astrophysics Data System (ADS)

Datta, Subhendu; Ledbetter, Hassel; Lei, Ming

The salient features of the elastic properties of uniaxial-fiber-reinforced composites are examined by considering the complete set of elastic constants of composites comprising isotropic uniaxial fibers in an isotropic matrix. Such materials exhibit transverse-isotropic symmetry and five independent elastic constants in Voigt notation: C(11), C(33), C(44), C(66), and C(13). These C(ij) constants are calculated over the entire fiber-volume-fraction range 0.0-1.0, using a scattered-plane-wave ensemple-average model. Some practical elastic constants such as the principal Young moduli and the principal Poisson ratios are considered, and the behavior of these constants is discussed. Also presented are the results for the four principal sound velocities used to study uniaxial-fiber-reinforced composites: v(11), v(33), v(12), and v(13).

Field Performance of Fiber-Reinforced Concrete Airfield Pavements.

DTIC Science & Technology

1986-07-01

were less severe at some fiver-reinforced concrete pavements at JFK airport in New York than at some of the other airports. The pavements at JFK ... airport did use a poly- ethylene sheet as a bond breaker between the fiber-reinforced overlay and base pavement. This may have helped reduce frictional

Preparation, assessment, and comparison of α-chitin nano-fiber films with different surface charges

NASA Astrophysics Data System (ADS)

Zhang, Yan; Jiang, Jie; Liu, Liang; Zheng, Ke; Yu, Shiyuan; Fan, Yimin

2015-05-01

Chitin nano-fibers with positive and negative charges have been, respectively, produced from partially deacetylated and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidized α-chitin. The average diameters and lengths of the TEMPO-oxidized chitin nano-fibers (TOChN) were 14 ± 4.3 and 190 ± 140 nm, respectively, and the average diameters and lengths of the partially deacetylated chitin nano-fibers (DEChN) were 6 ± 1.7 and 320 ± 105 nm, respectively. A partially deacetylated chitin nano-fiber film (DEChN-F), a TEMPO-mediated and oxidized chitin nano-fiber film (TOChN-F), and a composite film (DE-TO-ChN-F) consisting of a combination of the two were prepared by drying the dispersions at 40 °C. The DEChN-F, TOChN-F, and DE-TO-ChN-F all have similar tensile strengths of approximately 90 MPa; however, the chitosan film (Chitosan-F) had a tensile strength of approximately 30 MPa. In addition, TOChN-F and DE-TO-ChN-F have a thermal weight loss at 210 °C, and DEChN-F has a thermal weight loss at 280 °C. DEChN-F was found to have antimicrobial activity with regards to Escherichia coli. Finally, the chitin nano-fiber films could be slightly degraded by cellulase, which provided a novel biological performance of the chitin nano-material.

Energy Absorption Capacity in Natural Fiber Reinforcement Composites Structures

PubMed Central

López-Alba, Elías; Díaz, Francisco

2018-01-01

The study of natural fiber reinforcement composite structures has focused the attention of the automobile industry due to the new regulation in relation to the recyclability and the reusability of the materials preserving and/or improving the mechanical characteristics. The influence of different parameters on the material behavior of natural fiber reinforced plastic structures has been investigated, showing the potential for transport application in energy absorbing structures. Two different woven fabrics (twill and hopsack) made of flax fibers as well as a non-woven mat made of a mixture of hemp and kenaf fibers were employed as reinforcing materials. These reinforcing textiles were impregnated with both HD-PE (high-density polyethylen) and PLA (polylactic acid) matrix, using a continuous compression molding press. The impregnated semi-finished laminates (so-called organic sheets) were thermoformed in a second step to half-tubes that were assembled through vibration-welding process to cylindric crash absorbers. The specimens were loaded by compression to determine the specific energy absorption capacity. Quasi-static test results were compared to dynamic test data obtained on a catapult arrangement. The differences on the specific energies absorption (SEA) as a function of different parameters, such as the wall thickness, the weave material type, the reinforced textiles, and the matrix used, depending on the velocity rate application were quantified. In the case of quasi-static analysis it is observed a 20% increment in the SEA value when wove Hopsack fabric reinforcement is employed. No velocity rate influence from the material was observed on the SEA evaluation at higher speeds used to perform the experiments. The influence of the weave configuration (Hopsack) seems to be more stable against buckling effects at low loading rates with 10% higher SEA values. An increase of SEA level of up to 72% for PLA matrix was observed when compared with HD-PE matrix. PMID

Energy Absorption Capacity in Natural Fiber Reinforcement Composites Structures.

PubMed

López-Alba, Elías; Schmeer, Sebastian; Díaz, Francisco

2018-03-13

The study of natural fiber reinforcement composite structures has focused the attention of the automobile industry due to the new regulation in relation to the recyclability and the reusability of the materials preserving and/or improving the mechanical characteristics. The influence of different parameters on the material behavior of natural fiber reinforced plastic structures has been investigated, showing the potential for transport application in energy absorbing structures. Two different woven fabrics (twill and hopsack) made of flax fibers as well as a non-woven mat made of a mixture of hemp and kenaf fibers were employed as reinforcing materials. These reinforcing textiles were impregnated with both HD-PE (high-density polyethylen) and PLA (polylactic acid) matrix, using a continuous compression molding press. The impregnated semi-finished laminates (so-called organic sheets) were thermoformed in a second step to half-tubes that were assembled through vibration-welding process to cylindric crash absorbers. The specimens were loaded by compression to determine the specific energy absorption capacity. Quasi-static test results were compared to dynamic test data obtained on a catapult arrangement. The differences on the specific energies absorption (SEA) as a function of different parameters, such as the wall thickness, the weave material type, the reinforced textiles, and the matrix used, depending on the velocity rate application were quantified. In the case of quasi-static analysis it is observed a 20% increment in the SEA value when wove Hopsack fabric reinforcement is employed. No velocity rate influence from the material was observed on the SEA evaluation at higher speeds used to perform the experiments. The influence of the weave configuration (Hopsack) seems to be more stable against buckling effects at low loading rates with 10% higher SEA values. An increase of SEA level of up to 72% for PLA matrix was observed when compared with HD-PE matrix.

Performance of PTFE-lined composite journal bearings

NASA Technical Reports Server (NTRS)

Sliney, H. E.; Williams, F. J.

1982-01-01

Plain cylindrical journal bearings consisting of aramid fiber reinforced epoxy outer shells and glass fiber reinforced PTFE lubricating liners were evaluated. All materials in these bearings are electrically nonconductive; thus eliminating the problem of galvanic corrosion sometimes encountered with metal bearings installed in dissimilar metal mountings. Friction and wear characteristics were determined for loads, temperatures, and oscillating conditions that are typical of current airframe bearing applications. Friction and wear characteristics were found to be compatible with most airframe bearing requirements from -23 C to 121 C. Contamination with MIL H-5606 hydraulic fluid increased wear of the PTFE liners at 121 C, but did not affect the structural integrity of the aramid/epoxy composite.

Stress transfer of a Kevlar 49 fiber pullout test studied by micro-Raman spectroscopy.

PubMed

Lei, Zhenkun; Wang, Quan; Qiu, Wei

2013-06-01

The interfacial stress transfer behavior of a Kevlar 49 aramid fiber-epoxy matrix was studied with fiber pullout tests, the fibers of which were stretched by a homemade microloading device. Raman spectra on the embedded fiber were recorded by micro-Raman spectroscopy, under different strain levels. Then, the fiber axial stress was obtained by the relationship between the stress and Raman shift of the aramid fiber. Experimental results revealed that the fiber axial stress increased significantly with the load. The shear stress concentration occurred at the fiber entry to the epoxy resin. Thus, interfacial friction stages exist in the debonded fiber segment, and the interfacial friction shear stress is constant within one stage. The experimental results are consistent with the theoretical model predictions.

[Clinical evaluation of "All-on-Four" provisional prostheses reinforced with carbon fibers].

PubMed

Li, Bei-bei; Lin, Ye; Cui, Hong-yan; Hao, Qiang; Xu, Jia-bin; Di, Ping

2016-02-18

To assess the clinical effects of carbon fiber reinforcement on the "All-on-Four" provisional prostheses. Provisional prostheses were divided into control group and carbon fiber reinforcing group according to whether carbon fiber reinforcement was used in the provisional prostheses base resin. In our study, a total of 60 patients (32 males and 28 females) with 71 provisional prostheses(28 maxilla and 43 mandible)were enrolled between April 2008 and December 2012 for control group; a total of 23 patients (13 males and 10 females) with 28 provisional prostheses (9 maxillas and 19 mandibles) were enrolled between January 2013 and March 2014 for carbon fiber reinforcing group. The information of provisional prostheses in the patients was recorded according to preoperative examination. We used the date of definitive prosthesis restoration as the cut-off point, observing whether fracture occurred on the provisional prostheses in the two groups. Additionally we observed whether fiber exposure occurred on the tissue surface of the provisional prostheses and caused mucosal irritation. The interface between the denture base resin and the fibers was examined using scanning electron microscopy (SEM). The age [(57.3 ± 10.1) years vs.(55.1 ± 11.4) years], gender (32 males and 28 females vs. 13 males and 10 females), maxilla and mandible distributions (28 maxillas and 43 mandibles vs. 9 maxillas and 19 mandibles), the number of extraction jaws (46 vs. 23), the average using time [(7.8 ± 1.3) months vs. (7.5 ± 1.1) months], and the opposing dentition distributions of provisional prostheses of the patients showed no significant differences between the control and reinforcing groups. There were 21(29.6%) fractures that occurred on the 71 provisional prostheses in the control group; there was no fracture that occurred on the 28 provisional prosthesesin the carbon fiber reinforcing group. The fracture rate of the carbon fiber reinforcing group was significantly lower than that of

Characteristics and applications of high-performance fiber reinforced asphalt concrete

NASA Astrophysics Data System (ADS)

Park, Philip

Steel fiber reinforced asphalt concrete (SFRAC) is suggested in this research as a multifunctional high performance material that can potentially lead to a breakthrough in developing a sustainable transportation system. The innovative use of steel fibers in asphalt concrete is expected to improve mechanical performance and electrical conductivity of asphalt concrete that is used for paving 94% of U. S. roadways. In an effort to understand the fiber reinforcing mechanisms in SFRAC, the interaction between a single straight steel fiber and the surrounding asphalt matrix is investigated through single fiber pull-out tests and detailed numerical simulations. It is shown that pull-out failure modes can be classified into three types: matrix, interface, and mixed failure modes and that there is a critical shear stress, independent of temperature and loading rate, beyond which interfacial debonding will occur. The reinforcing effects of SFRAC with various fiber sizes and shapes are investigated through indirect tension tests at low temperature. Compared to unreinforced specimens, fiber reinforced specimens exhibit up to 62.5% increase in indirect tensile strength and 895% improvements in toughness. The documented improvements are the highest attributed to fiber reinforcement in asphalt concrete to date. The use of steel fibers and other conductive additives provides an opportunity to make asphalt pavement electrically conductive, which opens up the possibility for multifunctional applications. Various asphalt mixtures and mastics are tested and the results indicate that the electrical resistivity of asphaltic materials can be manipulated over a wide range by replacing a part of traditional fillers with a specific type of graphite powder. Another important achievement of this study is development and validation of a three dimensional nonlinear viscoelastic constitutive model that is capable of simulating both linear and nonlinear viscoelasticity of asphaltic materials. The

Continuous fiber-reinforced titanium aluminide composites

NASA Technical Reports Server (NTRS)

Mackay, R. A.; Brindley, P. K.; Froes, F. H.

1991-01-01

An account is given of the fabrication techniques, microstructural characteristics, and mechanical behavior of a lightweight, high service temperature SiC-reinforced alpha-2 Ti-14Al-21Nb intermetallic-matrix composite. Fabrication techniques under investigation to improve the low-temperature ductility and environmental resistance of this material system, while reducing manufacturing costs to competitive levels, encompass powder-cloth processing, foil-fiber-foil processing, and thermal-spray processing. Attention is given to composite microstructure problems associated with fiber distribution and fiber-matrix interfaces, as well as with mismatches of thermal-expansion coefficient; major improvements are noted to be required in tensile properties, thermal cycling effects, mechanical damage, creep, and environmental effects.

Interface stresses in fiber-reinforced materials with regular fiber arrangements

NASA Astrophysics Data System (ADS)

Mueller, W. H.; Schmauder, S.

The theory of linear elasticity is used here to analyze the stresses inside and at the surface of fiber-reinforced composites. Plane strain, plane stress, and generalized plane strain are analyzed using the shell model and the BHE model and are numerically studied using finite element analysis. Interface stresses are shown to depend weakly on Poisson's ratio. For equal values of the ratio, generalized plane strain and plane strain results are identical. For small volume fractions up to 40 vol pct of fibers, the shell and the BHE models predict the interface stresses very well over a wide range of elastic mismatches and for different fiber arrangements. At higher volume fractions the stresses are influenced by interactions with neighboring fibers. Introducing an external pressure into the shell model allows the prediction of interface stresses in real composite with isolated or regularly arranged fibers.

Flexural and Tensile Properties of Thin, Very High-Strength, Fiber-Reinforced Concrete Panels

DTIC Science & Technology

2008-09-01

Fiber - Reinforced Concrete Panels Michael J. Roth September 2008 G eo te ch ni ca l a nd S tr uc tu re s La bo ra to ry Approved for...Tensile Properties of Thin, Very High-Strength, Fiber - Reinforced Concrete Panels Michael J. Roth Geotechnical and Structures Laboratory U.S. Army...of Michigan, Ann Arbor, and noted authority in the field of 160 fiber - reinforced concrete . Implementation of Li’s work

Preparation and characterization of reinforced papers using nano bacterial cellulose.

PubMed

Tabarsa, Taghi; Sheykhnazari, Somayeh; Ashori, Alireza; Mashkour, Mahdi; Khazaeian, Abolghasem

2017-08-01

The main goal of this work was to reinforce softwood pulp (SP) with bacterial cellulose (BC) to generate a sustainable biocomposite. BC is a nanocellulose, which was anticipated to increase interfacial adhesion between the cellulosic fibers and BC. The organism used was Gluconacetobacter xylinus, which was incubated in a static Hestrin-Schramm culture at 28°C for 14days. The specimens of BC, SP and the reinforced SP with BC were characterized using X-ray diffraction (XRD), FT-IR, FESEM, and physico-mechanical testing. The crystallinity index was found to be 83 and 54% for BC and SP, respectively. FT-IR spectra showed that the composition of BC was fully different from that of SP fibers. Based on FESEM images, one can conclude that BC and softwood fibers do form a good combination with a nonporous structure. BC fibers fill in among the softwood fibers in the sheet. The physical and mechanical properties showed that as the dosage of BC increased, the properties of tensile index, tear index, and burst index greatly improved, while the porosity and the elongation decreased. The reason for the improved mechanical properties can be attributed to the increase of interfibrillar bonding which reduced porosity. This would be due to the high aspect ratio of BC that is capable of connecting between the cellulosic fibers and BC nanofibers, enhancing a large contact surface and therefore producing excellent coherence. This study suggests that BC could be a promising material for reinforcing composites at low loading. Copyright © 2017 Elsevier B.V. All rights reserved.

Reinforcing effects of different fibers on denture base resin based on the fiber type, concentration, and combination.

PubMed

Yu, Sang-Hui; Lee, Yoon; Oh, Seunghan; Cho, Hye-Won; Oda, Yutaka; Bae, Ji-Myung

2012-01-01

The aim of this study was to evaluate the reinforcing effects of three types of fibers at various concentrations and in different combinations on flexural properties of denture base resin. Glass (GL), polyaromatic polyamide (PA) and ultra-high molecular weight polyethylene (PE) fibers were added to heat-polymerized denture base resin with volume concentrations of 2.6%, 5.3%, and 7.9%, respectively. In addition, hybrid fiber-reinforced composite (FRC) combined with either two or three types of fibers were fabricated. The flexural strength, modulus and toughness of each group were measured with a universal testing machine at a crosshead speed of 5 mm/min. In the single fiber-reinforced composite groups, the 5.3% GL and 7.9% GL had the highest flexural strength and modulus; 5.3% PE was had the highest toughness. Hybrid FRC such as GL/PE, which showed the highest toughness and the flexural strength, was considered to be useful in preventing denture fractures clinically.

On the role of CFRP reinforcement for wood beams stiffness

NASA Astrophysics Data System (ADS)

Ianasi, A. C.

2015-11-01

In recent years, carbon fiber composites have been increasingly used in different ways in reinforcing structural elements. Specifically, the use of composite materials as a reinforcement for wood beams under bending loads requires paying attention to several aspects of the problem such as the number of the composite layers applied on the wood beams. Study consolidation of composites revealed that they are made by bonding fibrous material impregnated with resin on the surface of various elements, to restore or increase the load carrying capacity (bending, cutting, compression or torque) without significant damage of their rigidity. Fibers used in building applications can be fiberglass, aramid or carbon. Items that can be strengthened are concrete, brick, wood, steel and stone, and in terms of structural beams, walls, columns and floors. This paper describes an experimental study which was designed to evaluate the effect of composite material on the stiffness of the wood beams. It proposes a summary of the fundamental principles of analysis of composite materials and the design and use. The type of reinforcement used on the beams is the carbon fiber reinforced polymer (CFRP) sheet and plates and also an epoxy resin for bonding all the elements. Structural epoxy resins remain the primary choice of adhesive to form the bond to fiber-reinforced plastics and are the generally accepted adhesives in bonded CFRP-wood connections. The advantages of using epoxy resin in comparison to common wood-laminating adhesives are their gap-filling qualities and the low clamping pressures that are required to form the bond between carbon fiber plates or sheets and the wood beams. Mechanical tests performed on the reinforced wood beams showed that CFRP materials may produce flexural displacement and lifting increases of the beams. Observations of the experimental load-displacement relationships showed that bending strength increased for wood beams reinforced with CFRP composite plates

Effects of Interface Modification on Mechanical Behavior of Hi-Nicalon Fiber-Reinforced Celsian Matrix Composites

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Eldridge, Jeffrey I.

1997-01-01

Unidirectional celsian matrix composites having approx. 42 volume percent of uncoated or BN/SiC-coated Hi-Nicalon fibers were tested in three-point bend at room temperature. The uncoated fiber-reinforced composites showed catastrophic failure with strength of 210 +/- 35 MPa and a flat fracture surface. In contrast, composites reinforced with BN/SiC-coated fibers exhibited graceful failure with extensive fiber pullout. Values of first matrix cracking stress and strain were 435 +/- 35 MPa and 0.27 +/- 0.01 %, respectively, with ultimate strength as high as 960 MPa. The elastic Young's modulus of the uncoated and BN/SiC-coated fiber-reinforced composites were measured as 184 q 4 GPa and 165 +/- 5 GPa, respectively. Fiber push-through tests and microscopic examination indicated no chemical reaction at the uncoated or coated fiber-matrix interface. The low strength of the uncoated fiber-reinforced composite is probably due to degradation of the fibers from mechanical surface damage during processing. Because both the coated and uncoated fiber reinforced composites exhibited weak interfaces, the beneficial effect of the BN-SiC dual layer is primarily the protection of fibers from mechanical damage during processing.

Could Nano-Structured Materials Enable the Improved Pressure Vessels for Deep Atmospheric Probes?

NASA Technical Reports Server (NTRS)

Srivastava, D.; Fuentes, A.; Bienstock, B.; Arnold, J. O.

2005-01-01

A viewgraph presentation on the use of Nano-Structured Materials to enable pressure vessel structures for deep atmospheric probes is shown. The topics include: 1) High Temperature/Pressure in Key X-Environments; 2) The Case for Use of Nano-Structured Materials Pressure Vessel Design; 3) Carbon based Nanomaterials; 4) Nanotube production & purification; 5) Nanomechanics of Carbon Nanotubes; 6) CNT-composites: Example (Polymer); 7) Effect of Loading sequence on Composite with 8% by volume; 8) Models for Particulate Reinforced Composites; 9) Fullerene/Ti Composite for High Strength-Insulating Layer; 10) Fullerene/Epoxy Composite for High Strength-Insulating Layer; 11) Models for Continuous Fiber Reinforced Composites; 12) Tensile Strength for Discontinuous Fiber Composite; 13) Ti + SWNT Composites: Thermal/Mechanical; 14) Ti + SWNT Composites: Tensile Strength; and 15) Nano-structured Shell for Pressure Vessels.

Applications of fiber reinforced concrete containers in France and in Slovakia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verdier, A.; Delgrande, J.; Remias, V.

Radioactive waste immobilization is an integral part of operations in nuclear facilities. The goal of immobilization is to contain radioactive materials in a waste form which can maintain its integrity over very long periods of time, thus effectively isolating the materials from the environment and hence from the public. This is true regardless of the activity of the waste, including low-, and medium-level waste (LLW, MLW). A multiple-year research effort by COGEMA culminated in the development of a new process to immobilize nuclear waste in concrete containers reinforced with metal fibers. The fiber reinforced concrete containers satisfy all French safetymore » requirements relating to waste immobilization and disposal, and have been certified by ANDRA, the national radioactive waste management agency. The fiber reinforced concrete containers have been fabricated on a production scale since July 1990 by Sogefibre, a jointly-owned subsidiary of SGN and Campaign Generale des Eaux. This technology is being transferred to Slovenske Elektrarne (Slovak Power Plant) to intern the waste produced by Bohunice and Mochovce power plants in cubical fiber reinforced concrete containers.« less

Fuselage structure using advanced technology fiber reinforced composites

NASA Technical Reports Server (NTRS)

Robinson, R. K.; Tomlinson, H. M. (Inventor)

1982-01-01

A fuselage structure is described in which the skin is comprised of layers of a matrix fiber reinforced composite, with the stringers reinforced with the same composite material. The high strength to weight ratio of the composite, particularly at elevated temperatures, and its high modulus of elasticity, makes it desirable for use in airplane structures.

Effect of thermal cycling on composites reinforced with two differently sized silica-glass fibers.

PubMed

Meriç, Gökçe; Ruyter, I Eystein

2007-09-01

To evaluate the effects of thermal cycling on the flexural properties of composites reinforced with two differently sized fibers. Acid-washed, woven, fused silica-glass fibers, were heat-treated at 500 degrees C, silanized and sized with one of two sizing resins (linear poly(butyl methacrylate)) (PBMA), cross-linked poly(methyl methacrylate) (PMMA). Subsequently the fibers were incorporated into a polymer matrix. Two test groups with fibers and one control group without fibers were prepared. The flexural properties of the composite reinforced with linear PBMA-sized fibers were evaluated by 3-point bend testing before thermal cycling. The specimens from all three groups were thermally cycled in water (12,000 cycles, 5/55 degrees C, dwell time 30 s), and afterwards tested by 3-point bending. SEM micrographs were taken of the fibers and of the fractured fiber reinforced composites (FRC). The reduction of ultimate flexural strength after thermal cycling was less than 20% of that prior to thermal cycling for composites reinforced with linear PBMA-sized silica-glass fibers. The flexural strength of the composite reinforced with cross-linked PMMA-sized fibers was reduced to less than half of the initial value. This study demonstrated that thermal cycling differently influences the flexural properties of composites reinforced with different sized silica-glass fibers. The interfacial linear PBMA-sizing polymer acts as a stress-bearing component for the high interfacial stresses during thermal cycling due to the flexible structure of the linear PBMA above Tg. The cross-linked PMMA-sizing, however, acts as a rigid component and therefore causes adhesive fracture between the fibers and matrix after the fatigue process of thermal cycling and flexural fracture.

Preparation, assessment, and comparison of α-chitin nano-fiber films with different surface charges.

PubMed

Zhang, Yan; Jiang, Jie; Liu, Liang; Zheng, Ke; Yu, Shiyuan; Fan, Yimin

2015-01-01

Chitin nano-fibers with positive and negative charges have been, respectively, produced from partially deacetylated and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidized α-chitin. The average diameters and lengths of the TEMPO-oxidized chitin nano-fibers (TOChN) were 14 ± 4.3 and 190 ± 140 nm, respectively, and the average diameters and lengths of the partially deacetylated chitin nano-fibers (DEChN) were 6 ± 1.7 and 320 ± 105 nm, respectively. A partially deacetylated chitin nano-fiber film (DEChN-F), a TEMPO-mediated and oxidized chitin nano-fiber film (TOChN-F), and a composite film (DE-TO-ChN-F) consisting of a combination of the two were prepared by drying the dispersions at 40 °C. The DEChN-F, TOChN-F, and DE-TO-ChN-F all have similar tensile strengths of approximately 90 MPa; however, the chitosan film (Chitosan-F) had a tensile strength of approximately 30 MPa. In addition, TOChN-F and DE-TO-ChN-F have a thermal weight loss at 210 °C, and DEChN-F has a thermal weight loss at 280 °C. DEChN-F was found to have antimicrobial activity with regards to Escherichia coli. Finally, the chitin nano-fiber films could be slightly degraded by cellulase, which provided a novel biological performance of the chitin nano-material.

Matrix cracking with irregular fracture fronts as observed in fiber reinforced ceramic composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, K.X.; Yeh, C.P.; Wyatt, K.W.

1998-01-01

As a result of matrix cracking in fiber reinforced composites, fracture planforms assume a wide variation of profiles due to the fact that fiber bridging strongly affects the behavior of local crack fronts. This observation raises the question on the legitimacy of commonly used penny-shaped crack solutions when applied to fiber reinforced composites. Accordingly, investigation of the effects of fracture front profiles on mechanical responses is the thrust of this paper. The authors start with the solution of a penny-shaped crack in a unidirectional, fiber reinforced composite, which demonstrates necessity of considering wavy fracture fronts in fiber reinforced composites. Amore » theoretical framework for fiber reinforced composites with irregular fracture fronts due to matrix cracking is then established via a micromechanics model. The difference between small crack-size matrix cracking and large crack-size matrix cracking is investigated in detail. It is shown that the bridging effect is insignificant when matrix crack size is small and solution of effective property are obtained using Mori-Tanaka`s method by treating cracks and reinforcing fibers as distinct, but interacting phases. When the crack size becomes large, the bridging effects has to be taken into consideration. With bridging tractions obtained in consistency with the micromechanics solution, and corresponding crack energy backed out, the effective properties are obtained through a modification of standard Mori-Tanaka`s treatment of multiphase composites. Analytical solutions show that the generalization of a crack density of a penny-shaped planform is insufficient in describing the effective responses of fiber-reinforced composites with matrix cracking. Approximate solutions that account for the effects of the irregularity of crack planforms are given in closed forms for several irregular crack planforms, including cracks of cross rectangle, polygon and rhombus.« less

Reinforcing effect of discontinuous microglass fibers on resin-modified glass ionomer cement.

PubMed

Garoushi, Sufyan; Vallittu, Pekka K; Lassila, Lippo

2018-06-08

This study investigated the reinforcing effect of discontinuous-glass fiber fillers with different loading-fractions on selected mechanical properties and wear of resin-modified glass ionomer cement (RMGIC). Experimental fiber-reinforced RMGIC (Exp-RMGIC) was prepared by adding discontinuous-glass fiber of 200-500 µm in length to the powder of RMGIC (GC Fuji II LC) with different weight ratios (15, 20, 25 and 30 wt%). Mechanical properties and wear were determined for each experimental and control material. Scanning electron microscopy was used to evaluate the microstructure of the Exp-RMGICs. Wear pattern was analyzed by a three-dimensional (3D) noncontact optical profilometer. Fiber-reinforced RMGIC (30 wt%) had significantly higher mechanical performance of fracture toughness (1.9 MPa•m 1/2 ), flexural strength (90.3 MPa), and diametral tensile strength (31 MPa) (p<0.05) compared to unreinforced material (0.8 MPa•m 1/2 , 51.9 and 20.7 MPa). The use of discontinuous-glass fiber fillers with RMGIC matrix is novel reinforcement and yielded superior toughening and flexural performance compared to conventional RMGIC.

Carbon Fiber Reinforced Carbon Composite Valve for an Internal Combustion Engine

NASA Technical Reports Server (NTRS)

Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

1999-01-01

A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers throughout the valve's stem and head is disclosed. The valve includes braided carbon fiber material over axially aligned unidirectional carbon fibers forming a valve stem; the braided and unidirectional carbon fibers being broomed out at one end of the valve stem forming the shape of the valve head; the valve-shaped structure being densified and rigidized with a matrix of carbon containing discontinuous carbon fibers: and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.

Reinforcement of timber beams with carbon fibers reinforced plastics

NASA Astrophysics Data System (ADS)

Gugutsidze, G.; Draškovič, F.

2010-06-01

Wood is a polymeric material with many valuable features and which also lacks some negative features. In order to keep up with high construction rates and the minimization of negative effects, wood has become one of the most valuable materials in modern engineering. But the use of timber material economically is also an actual problem in order to protect the environment and improve natural surroundings. A panel of scientists is interested in solving these problems and in creating rational structures, where timber can be used efficiently. These constructions are as follows: glue-laminated (gluelam), composed and reinforced wooden constructions. Composed and reinforced wooden constructions are examined less, but according to researches already carried out, it is clear that significant work can be accomplished in creating rational, highly effective and economic timber constructions. The paper deals with research on the formation of composed fiber-reinforced beams (CFRP) made of timber and provide evidence of their effectiveness. The aim of the paper is to investigate cross-bending of CFRP-reinforced gluelaminated timber beams. According to the results we were able to determine the additional effectiveness of reinforcement with CFRP (which depends on the CFRP material's quality, quantity and module of elasticity) on the mechanical features of timber and a whole beam.

A study on the crushing behavior of basalt fiber reinforced composite structures

NASA Astrophysics Data System (ADS)

Pandian, A.; Veerasimman, A. P.; Vairavan, M.; Francisco, C.; Sultan, M. T. H.

2016-10-01

The crushing behavior and energy absorption capacity of basalt fiber reinforced hollow square structure composites are studied under axial compression. Using the hand layup technique, basalt fiber reinforced composites were fabricated using general purpose (GP) polyester resin with the help of wooden square shaped mould of varying height (100 mm, 150 mm and 200 mm). For comparison, similar specimens of glass fiber reinforced polymer composites were also fabricated and tested. Axial compression load is applied over the top end of the specimen with cross head speed as 2 mm/min using Universal Testing Machine (UTM). From the experimental results, the load-deformation characteristics of both glass fiber and basalt fiber composites were investigated. Crashworthiness and mode of collapse for the composites were determined from load-deformation curve, and they were then compared to each other in terms of their crushing behaviors.

Ceramic fiber reinforced glass-ceramic matrix composite

NASA Technical Reports Server (NTRS)

Bansal, Narottam P. (Inventor)

1993-01-01

A slurry of BSAS glass powders is cast into tapes which are cut to predetermined sizes. Mats of continuous chemical vapor deposition (CVD)-SiC fibers are alternately stacked with these matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite which is heated to burn out organic constituents. The remaining interim material is then hot-pressed to form a BSAS glass-ceramic fiber-reinforced composite.

Mullite fiber reinforced reaction bonded Si3N4 composites

NASA Technical Reports Server (NTRS)

Saleh, T.; Sayir, A.; Lightfoot, A.; Haggerty, J.

1996-01-01

Fracture toughnesses of brittle ceramic materials have been improved by introducing reinforcements and carefully tailored interface layers. Silicon carbide and Si3N4 have been emphasized as matrices of structural composites intended for high temperature service because they combine excellent mechanical, chemical, thermal and physical properties. Both matrices have been successfully toughened with SiC fibers, whiskers and particles for ceramic matrix composite (CMC) parts made by sintering, hot pressing or reaction forming processes. These SiC reinforced CMCs have exhibited significantly improved toughnesses at low and intermediate temperature levels, as well as retention of properties at high temperatures for selected exposures; however, they are vulnerable to attack from elevated temperature dry and wet oxidizing atmospheres after the matrix has cracked. Property degradation results from oxidation of interface layers and/or reinforcements. The problem is particularly acute for small diameter (-20 tim) polymer derived SiC fibers used for weavable toes. This research explored opportunities for reinforcing Si3N4 matrices with fibers having improved environmental stability; the findings should also be applicable to SiC matrix CMCs.

Influence of Hybridizing Flax and Hemp-Agave Fibers with Glass Fiber as Reinforcement in a Polyurethane Composite

PubMed Central

Pandey, Pankaj; Bajwa, Dilpreet; Ulven, Chad; Bajwa, Sreekala

2016-01-01

In this study, six combinations of flax, hemp, and glass fiber were investigated for a hybrid reinforcement system in a polyurethane (PU) composite. The natural fibers were combined with glass fibers in a PU composite in order to achieve a better mechanical reinforcement in the composite material. The effect of fiber hybridization in PU composites was evaluated through physical and mechanical properties such as water absorption (WA), specific gravity (SG), coefficient of linear thermal expansion (CLTE), flexural and compression properties, and hardness. The mechanical properties of hybridized samples showed mixed trends compared to the unhybridized samples, but hybridization with glass fiber reduced water absorption by 37% and 43% for flax and hemp-agave PU composites respectively. PMID:28773512

Starch/polycaprolactone-containing composites reinforced with pre-treated sisal fibers

USDA-ARS?s Scientific Manuscript database

Composites based on thermoplastic cornstarch (TPS) and polycaprolactone (PCL) were reinforced with 5, 10 and 20% (wt%) of pretreated sisal fiber. The impact of the addition of sisal fiber on the mechanical, thermal and morphological properties of composites was investigated. Addition of 5-10% fibers...

Improving the mechanical performance of wood fiber reinforced bio-based polyurethane foam

NASA Astrophysics Data System (ADS)

Chang, Li-Chi

Because of the environmental impact of fossil fuel consumption, soybean-based polyurethane (PU) foam has been developed as an alternative to be used as the core in structural insulated panels (SIPs). Wood fibers can be added to enhance the resistance of foam against bending and buckling in compression. The goal of this work is to study the effect of three modifications: fiber surface treatment, catalyst choice, and mixing method on the compression performance of wood fiber-reinforced PU foam. Foams were made with a free-rising process. The compression performance of the foams was measured and the foams were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray computed tomography (CT). The foam reinforced with alkali-treated fibers had improved compression performance. The foams made with various catalysts shared similar performance. The foam made using a mechanical stirrer contained well-dispersed fibers but the reinforcing capability of the fibers was reduced.

Fiber reinforced thermoplastic resin matrix composites

NASA Technical Reports Server (NTRS)

Jones, Robert J. (Inventor); Chang, Glenn E. C. (Inventor)

1989-01-01

Polyimide polymer composites having a combination of enhanced thermal and mechanical properties even when subjected to service temperatures as high as 700.degree. F. are described. They comprise (a) from 10 to 50 parts by weight of a thermoplastic polyimide resin prepared from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and (b) from 90 to 50 parts by weight of continuous reinforcing fibers, the total of (a) and (b) being 100 parts by weight. Composites based on polyimide resin formed from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and pyromellitic dianhydride and continuous carbon fibers retained at least about 50% of their room temperature shear strength after exposure to 700.degree. F. for a period of 16 hours in flowing air. Preferably, the thermoplastic polyimide resin is formed in situ in the composite material by thermal imidization of a corresponding amide-acid polymer prepared from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. It is also preferred to initially size the continuous reinforcing fibers with up to about one percent by weight of an amide-acid polymer prepared from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. In this way imidization at a suitable elevated temperature results in the in-situ formation of a substantially homogeneous thermoplastic matrix of the polyimide resin tightly and intimately bonded to the continuous fibers. The resultant composites tend to have optimum thermo-mechanical properties.

New Polylactic Acid Composites Reinforced with Artichoke Fibers

PubMed Central

Botta, Luigi; Fiore, Vincenzo; Scalici, Tommaso; Valenza, Antonino; Scaffaro, Roberto

2015-01-01

In this work, artichoke fibers were used for the first time to prepare poly(lactic acid) (PLA)-based biocomposites. In particular, two PLA/artichoke composites with the same fiber loading (10% w/w) were prepared by the film-stacking method: the first one (UNID) reinforced with unidirectional long artichoke fibers, the second one (RANDOM) reinforced by randomly-oriented long artichoke fibers. Both composites were mechanically characterized in tensile mode by quasi-static and dynamic mechanical tests. The morphology of the fracture surfaces was analyzed through scanning electron microscopy (SEM). Moreover, a theoretical model, i.e., Hill’s method, was used to fit the experimental Young’s modulus of the biocomposites. The quasi-static tensile tests revealed that the modulus of UNID composites is significantly higher than that of the neat PLA (i.e., ~40%). Moreover, the tensile strength is slightly higher than that of the neat matrix. The other way around, the stiffness of RANDOM composites is not significantly improved, and the tensile strength decreases in comparison to the neat PLA.

Fiber orientation interpolation for the multiscale analysis of short fiber reinforced composite parts

NASA Astrophysics Data System (ADS)

Köbler, Jonathan; Schneider, Matti; Ospald, Felix; Andrä, Heiko; Müller, Ralf

2018-06-01

For short fiber reinforced plastic parts the local fiber orientation has a strong influence on the mechanical properties. To enable multiscale computations using surrogate models we advocate a two-step identification strategy. Firstly, for a number of sample orientations an effective model is derived by numerical methods available in the literature. Secondly, to cover a general orientation state, these effective models are interpolated. In this article we develop a novel and effective strategy to carry out this interpolation. Firstly, taking into account symmetry arguments, we reduce the fiber orientation phase space to a triangle in R^2 . For an associated triangulation of this triangle we furnish each node with an surrogate model. Then, we use linear interpolation on the fiber orientation triangle to equip each fiber orientation state with an effective stress. The proposed approach is quite general, and works for any physically nonlinear constitutive law on the micro-scale, as long as surrogate models for single fiber orientation states can be extracted. To demonstrate the capabilities of our scheme we study the viscoelastic creep behavior of short glass fiber reinforced PA66, and use Schapery's collocation method together with FFT-based computational homogenization to derive single orientation state effective models. We discuss the efficient implementation of our method, and present results of a component scale computation on a benchmark component by using ABAQUS ®.

Fiber orientation interpolation for the multiscale analysis of short fiber reinforced composite parts

NASA Astrophysics Data System (ADS)

Köbler, Jonathan; Schneider, Matti; Ospald, Felix; Andrä, Heiko; Müller, Ralf

2018-04-01

For short fiber reinforced plastic parts the local fiber orientation has a strong influence on the mechanical properties. To enable multiscale computations using surrogate models we advocate a two-step identification strategy. Firstly, for a number of sample orientations an effective model is derived by numerical methods available in the literature. Secondly, to cover a general orientation state, these effective models are interpolated. In this article we develop a novel and effective strategy to carry out this interpolation. Firstly, taking into account symmetry arguments, we reduce the fiber orientation phase space to a triangle in R^2 . For an associated triangulation of this triangle we furnish each node with an surrogate model. Then, we use linear interpolation on the fiber orientation triangle to equip each fiber orientation state with an effective stress. The proposed approach is quite general, and works for any physically nonlinear constitutive law on the micro-scale, as long as surrogate models for single fiber orientation states can be extracted. To demonstrate the capabilities of our scheme we study the viscoelastic creep behavior of short glass fiber reinforced PA66, and use Schapery's collocation method together with FFT-based computational homogenization to derive single orientation state effective models. We discuss the efficient implementation of our method, and present results of a component scale computation on a benchmark component by using ABAQUS ®.

Seawater infiltration effect on thermal degradation of fiber reinforced epoxy composites

NASA Astrophysics Data System (ADS)

Ibrahim, Mohd Haziq Izzuddin bin; Hassan, Mohamad Zaki bin; Ibrahim, Ikhwan; Rashidi, Ahmad Hadi Mohamed; Nor, Siti Fadzilah M.; Daud, Mohd Yusof Md

2018-05-01

Seawater salinity has been associated with the reduction of polymer structure durability. The aim of this study is to investigate the change in thermal degradation of fiber reinforced epoxy composite due to the presence of seawater. Carbon fiber, carbon/kevlar, fiberglass, and jute that reinforced with epoxy resin was laminated through hand-layup technique. Initially, these specimen was sectioned to 5×5 mm dimension, then immersed in seawater and distilled water at room temperature until it has thoroughly saturated. Following, the thermal degradation analysis using Differential Scanning Calorimetry (DSC), the thermic changes due to seawater infiltration was defined. The finding shows that moisture absorption reduces the glass transition temperature (Tg) of fiber reinforced epoxy composite. However, the glass transition temperature (Tg) of seawater infiltrated laminate composite is compareable with distilled water infiltrated laminate composite. The carbon fiber reinfored epoxy has the highest glass transition temperature out of all specimen.

CO2-laser-assisted processing of glass fiber-reinforced thermoplastic composites

NASA Astrophysics Data System (ADS)

Brecher, Christian; Emonts, Michael; Schares, Richard Ludwig; Stimpfl, Joffrey

2013-02-01

To fully exploit the potential of fiber-reinforced thermoplastic composites (FRTC) and to achieve a broad industrial application, automated manufacturing systems are crucial. Investigations at Fraunhofer IPT have proven that the use of laser system technology in processing FRTC allows to achieve high throughput, quality, flexibility, reproducibility and out-of-autoclave processing simultaneously. As 90% of the FRP in Europe1 are glass fiber-reinforced a high impact can be achieved by introducing laser-assisted processing with all its benefits to glass fiber-reinforced thermoplastics (GFRTC). Fraunhofer IPT has developed the diode laser-assisted tape placement (laying and winding) to process carbon fiber-reinforced thermoplastic composites (CFRTC) for years. However, this technology cannot be transferred unchanged to process milky transparent GFRTC prepregs (preimpregnated fibers). Due to the short wavelength (approx. 980 nm) and therefore high transmission less than 20% of the diode laser energy is absorbed as heat into non-colored GFRTC prepregs. Hence, the use of a different wave length, e.g. CO2-laser (10.6 μm) with more than 90% laser absorption, is required to allow the full potential of laser-assisted processing of GFRTC. Also the absorption of CO2-laser radiation at the surface compared to volume absorption of diode laser radiation is beneficial for the interlaminar joining of GFRTC. Fraunhofer IPT is currently developing and investigating the CO2-laser-assisted tape placement including new system, beam guiding, process and monitoring technology to enable a resource and energy efficient mass production of GFRP composites, e.g. pipes, tanks, masts. The successful processing of non-colored glass fiber-reinforced Polypropylene (PP) and Polyphenylene Sulfide (PPS) has already been proven.

Studies on fabrication of glass fiber reinforced composites using polymer blends

NASA Astrophysics Data System (ADS)

Patel, R. H.; Kachhia, P. H.; Patel, S. N.; Rathod, S. T.; Valand, J. K.

2018-05-01

Glass fiber reinforced PVC/NBR composites have been fabricated via hot compression moulding process. PVC is brittle in nature and thus lower thermal stability. Therefore, to improve the toughness of PVC, NBR was incorporated in certain proportions. As both are polar and thus they are compatible. To improve the strength property further, these blends were used to fabricate glass fiber reinforced composites. SEM micrograph shows good wettability of the blend with glass fibers resulting in proper bonding which increase the strength of the composites.

Structural Evolution of Silicon Oxynitride Fiber Reinforced Boron Nitride Matrix Composite at High Temperatures

NASA Astrophysics Data System (ADS)

Zou, Chunrong; Li, Bin; Zhang, Changrui; Wang, Siqing; Xie, Zhengfang; Shao, Changwei

2016-02-01

The structural evolution of a silicon oxynitride fiber reinforced boron nitride matrix (Si-N-Of/BN) wave-transparent composite at high temperatures was investigated. When heat treated at 1600 °C, the composite retained a favorable bending strength of 55.3 MPa while partially crystallizing to Si2N2O and h-BN from the as-received amorphous structure. The Si-N-O fibers still performed as effective reinforcements despite the presence of small pores due to fiber decomposition. Upon heat treatment at 1800 °C, the Si-N-O fibers already lost their reinforcing function and rough hollow microstructure formed within the fibers because of the accelerated decomposition. Further heating to 2000 °C led to the complete decomposition of the reinforcing fibers and only h-BN particles survived. The crystallization and decomposition behaviors of the composite at high temperatures are discussed.

Self-diagnosis of structures strengthened with hybrid carbon-fiber-reinforced polymer sheets

NASA Astrophysics Data System (ADS)

Wu, Z. S.; Yang, C. Q.; Harada, T.; Ye, L. P.

2005-06-01

The correlation of mechanical and electrical properties of concrete beams strengthened with hybrid carbon-fiber-reinforced polymer (HCFRP) sheets is studied in this paper. Two types of concrete beams, with and without reinforcing bars, are strengthened with externally bonded HCFRP sheets, which have a self-structural health monitoring function due to the electrical conduction and piezoresistivity of carbon fibers. Parameters investigated include the volume fractions and types of carbon fibers. According to the investigation, it is found that the hybridization of uniaxial HCFRP sheets with several different types of carbon fibers is a viable method for enhancing the mechanical properties and obtaining a built-in damage detection function for concrete structures. The changes in electrical resistance during low strain ranges before the rupture of carbon fibers are generally smaller than 1%. Nevertheless, after the gradual ruptures of carbon fibers, the electrical resistance increases remarkably with the strain in a step-wise manner. For the specimens without reinforcing bars, the electrical behaviors are not stable, especially during the low strain ranges. However, the electrical behaviors of the specimens with reinforcing bars are relatively stable, and the whole range of self-sensing function of the HCFRP-strengthened RC structures has realized the conceptual design of the HCFRP sensing models and is confirmed by the experimental investigations. The relationships between the strain/load and the change in electrical resistance show the potential self-monitoring capacity of HCFRP reinforcements used for strengthening concrete structures.

A New Fiber Preform with Nanocarbon Binder for Manufacturing Carbon Fiber Reinforced Composite by Liquid Molding Process.

PubMed

Seong, Dong Gi; Ha, Jong Rok; Lee, Jea Uk; Lee, Wonoh; Kim, Byung Sun

2015-11-01

Carbon fiber reinforced composite has been a good candidate of lightweight structural component in the automotive industry. As fast production speed is essential to apply the composite materials for the mass production area such as automotive components, the high speed liquid composite molding processes have been developed. Fast resin injection through the fiber preform by high pressure is required to improve the production speed, but it often results in undesirable deformations of the fiber preform which causes defectives in size and properties of the final composite products. In order to prevent the undesirable deformation and improve the stability of preform shape, polymer type binder materials are used. More stable fiber preform can be obtained by increasing the amount of binder material, but it disturbs the resin impregnation through the fiber preform. In this study, carbon nanomaterials such as graphene oxide were embedded on the surface of carbon fiber by electrophoretic deposition method in order to improve the shape stability of fiber preform and interfacial bonding between polymer and the reinforcing fiber. Effects of the modified reinforcing fiber were investigated in two respects. One is to increase the binding energy between fiber tows, and the other is to increase the interfacial bonding between polymer matrix and fiber surface. The effects were analyzed by measuring the binding force of fiber preform and interlaminar shear strength of the composite. This study also investigated the high speed liquid molding process of the composite materials composed of polymer matrix and the carbon fiber preforms embedded by carbon nanomaterials. Process parameter such as permeability of fiber preform was measured to investigate the effect of nanoscale surface modification on the macroscale processing condition for composite manufacturing.

Fracture of fiber-reinforced composites analyzed via acoustic emission.

PubMed

Ereifej, Nadia S; Oweis, Yara G; Altarawneh, Sandra K

2015-01-01

This study investigated the fracture resistance of composite resins using a three-point bending test and acoustic emission (AE) analysis. Three groups of specimens (n=15) were prepared: non-reinforced BelleGlass HP composite (NRC), unidirectional (UFRC) and multidirectional (MFRC) fiber-reinforced groups which respectively incorporated unidirectional Stick and multidirectional StickNet fibers. Specimens were loaded to failure in a universal testing machine while an AE system was used to detect audible signals. Initial fracture strengths and AE amplitudes were significantly lower than those at final fracture in all groups (p<0.05). Initial fracture strength of UFRC (170.0 MPa) was significantly higher than MFRC (124.6 MPa) and NRC (87.9 MPa). Final fracture strength of UFRC (198.1 MPa) was also significantly higher than MFRC (151.0 MPa) and NRC (109.2 MPa). Initial and final fracture strengths were significantly correlated (r=0.971). It was concluded that fiber reinforcement improved the fracture resistance of composite resin materials and the monitoring of acoustic signals revealed significant information regarding the fracture process.

Comparative evaluation between glass and polyethylene fiber reinforced composites: A review of the current literature

PubMed Central

Mangoush, Enas; Säilynoja, Eija; Prinssi, Roosa; Lassila, Lippo; Vallittu, Pekka K.

2017-01-01

Background Fiber reinforced composite (FRC) is a promising class of material that gives clinicians alternative treatment options. There are many FRC products available in the market based on either glass or polyethylene fiber type. The aim of this study was to present a comparison between glass and polyethylene fiber reinforced composites based on available literature review. Material and Methods A thorough literature search, with no limitation, was done up to June 2017. The range of relevant publications was surveyed using PubMed and Google Scholar. From the search results, articles related to our search terms were only considered. An assessment of these articles was done by two individuals in order to include only articles directly compare between glass and polyethylene FRCs. The search terms used were “fiber reinforced dental composites” and “glass and polyethylene fibers in dentistry”. Results The search provided 276 titles. Full-text analysis was performed for 29 articles that met the inclusion criteria. Most were laboratory-based research with various test specimen designs prepared according to ISO standard or with extracted teeth and only three articles were clinical studies. Most of studies (n=23) found superior characteristics of glass FRCs over polyethylene FRCs. Conclusions Significant reinforcement differences between commercial glass and polyethylene fiber reinforced composites were found. Key words:Fiber reinforced composite, glass fiber, polyethylene fiber. PMID:29410756

An Investigation of Fiber Reinforced Chemically Bonded Phosphate Ceramic Composites at Room Temperature.

PubMed

Ding, Zhu; Li, Yu-Yu; Lu, Can; Liu, Jian

2018-05-21

In this study, chemically bonded phosphate ceramic (CBPC) fiber reinforced composites were made at indoor temperatures. The mechanical properties and microstructure of the CBPC composites were studied. The CBPC matrix of aluminum phosphate binder, metakaolin, and magnesia with different Si/P ratios was prepared. The results show that when the Si/P ratio was 1.2, and magnesia content in the CBPC was 15%, CBPC reached its maximum flexural strength. The fiber reinforced CBPC composites were prepared by mixing short polyvinyl alcohol (PVA) fibers or unidirectional continuous carbon fiber sheets. Flexural strength and dynamic mechanical properties of the composites were determined, and the microstructures of specimens were analyzed by scanning electron micrography, X-ray diffraction, and micro X-ray computed tomography. The flexural performance of continuous carbon fiber reinforced CBPC composites was better than that of PVA fiber composites. The elastic modulus, loss modulus, and loss factor of the fiber composites were measured through dynamic mechanical analysis. The results showed that fiber reinforced CBPC composites are an inorganic polymer viscoelastic material with excellent damping properties. The reaction of magnesia and phosphate in the matrix of CBPC formed a different mineral, newberyite, which was beneficial to the development of the CBPC.

Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide.

PubMed

Kim, Gun-Hee; Lee, Jeong-Won; Seo, Tae-Il

2013-05-10

Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this study, the mechanical characteristic analysis of the glass-reinforced plastic worm wheel, according to the contents of glass fiber, is performed by analytic and experimental methods. In the case of the glass fiber-reinforced resin, the orientation and contents of glass fibers can influence the mechanical properties. For the characteristic prediction of plastic worm wheel, computer-aided engineering (CAE) analysis processes such as structural and injection molding analysis were executed with the polyamide resin reinforcement glass fiber (25 wt %, 50 wt %). The injection mold for fabricating the prototype plastic worm wheel was designed and made to reflect the CAE analysis results. Finally, the durability of prototype plastic worm wheel fabricated by the injection molding process was evaluated by the experimental method and the characteristics according to the glass fiber contents.

Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide

PubMed Central

Kim, Gun-Hee; Lee, Jeong-Won; Seo, Tae-Il

2013-01-01

Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this study, the mechanical characteristic analysis of the glass-reinforced plastic worm wheel, according to the contents of glass fiber, is performed by analytic and experimental methods. In the case of the glass fiber-reinforced resin, the orientation and contents of glass fibers can influence the mechanical properties. For the characteristic prediction of plastic worm wheel, computer-aided engineering (CAE) analysis processes such as structural and injection molding analysis were executed with the polyamide resin reinforcement glass fiber (25 wt %, 50 wt %). The injection mold for fabricating the prototype plastic worm wheel was designed and made to reflect the CAE analysis results. Finally, the durability of prototype plastic worm wheel fabricated by the injection molding process was evaluated by the experimental method and the characteristics according to the glass fiber contents. PMID:28809248

Multi-Length Scale-Enriched Continuum-Level Material Model for Kevlar-Fiber-Reinforced Polymer-Matrix Composites

DTIC Science & Technology

2012-08-03

is unlimited. Multi-Length Scale-Enriched Continuum-Level Material Model for Kevlar ®-Fiber-Reinforced Polymer-Matrix Composites The views, opinions...12211 Research Triangle Park, NC 27709-2211 ballistics, composites, Kevlar , material models, microstructural defects REPORT DOCUMENTATION PAGE 11... Kevlar ®-Fiber-Reinforced Polymer-Matrix Composites Report Title Fiber-reinforced polymer matrix composite materials display quite complex deformation

Factors Controlling Stress Rupture of Fiber-Reinforced Ceramic Composites

NASA Technical Reports Server (NTRS)

DiCarlo, J. A.; Yun, H. M.

1999-01-01

The successful application of fiber-reinforced ceramic matrix composites (CMC) depends strongly on maximizing material rupture life over a wide range of temperatures and applied stresses. The objective of this paper is to examine the various intrinsic and extrinsic factors that control the high-temperature stress rupture of CMC for stresses below and above those required for cracking of the 0 C plies (Regions I and II, respectively). Using creep-rupture results for a variety of ceramic fibers and rupture data for CMC reinforced by these fibers, it is shown that in those cases where the matrix carries little structural load, CMC rupture conditions can be predicted very well from the fiber behavior measured under the appropriate test environment. As such, one can then examine the intrinsic characteristics of the fibers in order to develop design guidelines for selecting fibers and fiber microstructures in order to maximize CMC rupture life. For those cases where the fiber interfacial coatings are unstable in the test environment, CMC lives are generally worse than those predicted by fiber behavior alone. For those cases where the matrix can support structural load, CMC life can even be greater provided matrix creep behavior is properly controlled. Thus the achievement of long CMC rupture life requires understanding and optimizing the behavior of all constituents in the proper manner.

Influence of nanosize clay platelets on the mechanical properties of glass fiber reinforced polyester composites.

PubMed

Jawahar, P; Balasubramanian, M

2006-12-01

Glass fiber reinforced polyester composite and hybrid nanoclay-fiber reinforced composites were prepared by hand lay-up process. The mechanical behavior of these materials and the changes as a result of the incorporation of both nanosize clay and glass fibers were investigated. Composites were prepared with a glass fibre content of 25 vol%. The proportion of the nanosize clay platelets was varied from 0.5 to 2.5 vol%. Hybrid clay-fiber reinforced polyester composite posses better tensile, flexural, impact, and barrier properties. Hybrid clay-fiber reinforced polyester composites also posses better shear strength, storage modulus, and glass transition temperature. The optimum properties were found to be with the hybrid laminates containing 1.5 vol% nanosize clay.

Investigation of fiber-reinforced concrete for use in transportation structures.

DOT National Transportation Integrated Search

1997-01-01

This report presents the results of a laboratory investigation to determine the properties of fiber-reinforced concretes (FRCs) with steel (hooked-end), polypropylene (monofilament and fibrillated), and the recently introduced polyolefin fibers (mono...

Microstructure and Mechanical Properties of Graphene-Reinforced Titanium Matrix/Nano-Hydroxyapatite Nanocomposites

PubMed Central

Li, Feng; Shao, Zhenyi; Zhu, Degui; Zhu, Minhao

2018-01-01

Biomaterial composites made of titanium and hydroxyapatite (HA) powder are among the most important biomedicalmaterials due to their good mechanical properties and biocompatibility. In this work, graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites were prepared by vacuum hot-pressing sintering. The microstructure and mechanical properties of graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were systematically investigated. Microstructures of the nanocomposites were examined by X-ray diffraction (XRD), back scattered electron imaging (BSE), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), electron probe microanalyzer (EPMA), and transmission electron microscope (TEM). The mechanical properties were determined from microhardness, shear strength, and compressive strength. Results showed that during the high-temperature sintering process, complex chemical reactions occurred, resulting in new phases of nucleation such as Ca3(PO4)2, TixPy, and Ti3O.The new phases, which easily dropped off under the action of external force, could hinder the densification of sintering and increase the brittleness of the nanocomposites. Results demonstrated that graphene had an impact on the microstructure and mechanical properties of the nanocomposites. Based on the mechanical properties and microstructure of the nanocomposites, the strengthening and fracture mechanisms of the graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were analyzed. PMID:29659504

Microstructure and Mechanical Properties of Graphene-Reinforced Titanium Matrix/Nano-Hydroxyapatite Nanocomposites.

PubMed

Li, Feng; Jiang, Xiaosong; Shao, Zhenyi; Zhu, Degui; Zhu, Minhao

2018-04-16

Biomaterial composites made of titanium and hydroxyapatite (HA) powder are among the most important biomedicalmaterials due to their good mechanical properties and biocompatibility. In this work, graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites were prepared by vacuum hot-pressing sintering. The microstructure and mechanical properties of graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were systematically investigated. Microstructures of the nanocomposites were examined by X-ray diffraction (XRD), back scattered electron imaging (BSE), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), electron probe microanalyzer (EPMA), and transmission electron microscope (TEM). The mechanical properties were determined from microhardness, shear strength, and compressive strength. Results showed that during the high-temperature sintering process, complex chemical reactions occurred, resulting in new phases of nucleation such as Ca₃(PO₄)₂, Ti x P y , and Ti₃O.The new phases, which easily dropped off under the action of external force, could hinder the densification of sintering and increase the brittleness of the nanocomposites. Results demonstrated that graphene had an impact on the microstructure and mechanical properties of the nanocomposites. Based on the mechanical properties and microstructure of the nanocomposites, the strengthening and fracture mechanisms of the graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were analyzed.

[A study on alpha-tricalcium phosphate bone cement carbon fiber-reinforced].

PubMed

Wu, Wenjin; Yang, Weizhong; Zhou, Dali; Ma, Jiang; Xiao, Bin

2006-06-01

In order to improve the mechanical properties of alpha-tricalcium phosphate (alpha-TCP), we prepared surface-modified carbon fibers (CF) reinforced alpha-TCP composite bone cement. Bone cement was soaked in Ringer's body solution to test its capacity of fast formation of hydroxyapatite crystals and self-solidification. Scan electronic microscope (SEM) observation and compressive strength measurement were taken to analyze the mechanical properties and the micro- morphological structure of CF reinforced alpha-TCP bone cement. The results showed that the bone cement was transferred into hydroxyapatite plates after being soaked in Ringer's simulated body fluid for 5 days. Suitable amount of carbon fibers could well spread in and bond with the matrix of the bone cement. The mechanical properties of the bone cement have been improved by CF reinforcing; the compressive strength reaches 46.7 MPa when the amount of carbon fibers is 0.5% in weight percent, which is 22% higher than that of the non-reinforced alpha-TCP bone cement.

Flexural properties of polyethylene, glass and carbon fiber-reinforced resin composites for prosthetic frameworks.

PubMed

Maruo, Yukinori; Nishigawa, Goro; Irie, Masao; Yoshihara, Kumiko; Minagi, Shogo

2015-01-01

High flexural properties are needed for fixed partial denture or implant prosthesis to resist susceptibility to failures caused by occlusal overload. The aim of this investigation was to clarify the effects of four different kinds of fibers on the flexural properties of fiber-reinforced composites. Polyethylene fiber, glass fiber and two types of carbon fibers were used for reinforcement. Seven groups of specimens, 2 × 2 × 25 mm, were prepared (n = 10 per group). Four groups of resin composite specimens were reinforced with polyethylene, glass or one type of carbon fiber. The remaining three groups served as controls, with each group comprising one brand of resin composite without any fiber. After 24-h water storage in 37°C distilled water, the flexural properties of each specimen were examined with static three-point flexural test at a crosshead speed of 0.5 mm/min. Compared to the control without any fiber, glass and carbon fibers significantly increased the flexural strength (p < 0.05). On the contrary, the polyethylene fiber decreased the flexural strength (p < 0.05). Among the fibers, carbon fiber exhibited higher flexural strength than glass fiber (p < 0.05). Similar trends were observed for flexural modulus and fracture energy. However, there was no significant difference in fracture energy between carbon and glass fibers (p > 0.05). Fibers could, therefore, improve the flexural properties of resin composite and carbon fibers in longitudinal form yielded the better effects for reinforcement.

Influence of BN fiber coatings on the interfacial structure of sapphire fiber reinforced NiAl composites

NASA Astrophysics Data System (ADS)

Reichert, K.; Wen, K.; Cremer, R.; Hu, W.; Neuschütz, D.; Gottstein, G.

2001-07-01

A new concept for a tailored fiber-matrix interface for sapphire fiber reinforced NiAl matrix composites is proposed, consisting of an initial hexagonal boron nitride (hBN) fiber coating. For this, single crystal Al 2O 3 fibers were coated with hBN by chemical vapor deposition (CVD). Following a comprehensive characterization of the CVD coating as to composition and structure by means of X-ray photoelectron spectroscopy (XPS) and grazing incidence X-ray diffraction (GIXRD), the fiber reinforced NiAl matrix composites were fabricated by diffusion bonding at 1400°C. The interfaces NiAl/BN and BN/Al 2O 3 were analyzed by scanning electron microscopy (SEM), analytical transmission electron microscopy (TEM), and selected area diffraction (SAD). An interfacial reaction between NiAl and hBN to form AlN was revealed using these analytical techniques.

Tungsten fiber reinforced copper matrix composites: A review

NASA Technical Reports Server (NTRS)

Mcdanels, David L.

1989-01-01

Tungsten fiber reinforced copper matrix (W/Cu) composites have served as an ideal model system with which to analyze the properties of metal matrix composites. A series of research programs were conducted to investigate the stress-strain behavior of W/Cu composites; the effect of fiber content on the strength, modulus, and conductivity of W/Cu composites; and the effect of alloying elements on the behavior of tungsten wire and of W/Cu composites. Later programs investigated the stress-rupture, creep, and impact behavior of these composites at elevated temperatures. Analysis of the results of these programs as allows prediction of the effects of fiber properties, matrix properties, and fiber content on the properties of W/Cu composites. These analyses form the basis for the rule-of-mixtures prediction of composite properties which was universally adopted as the criteria for measuring composite efficiency. In addition, the analyses allows extrapolation of potential properties of other metal matrix composites and are used to select candidate fibers and matrices for development of tungsten fiber reinforced superalloy composite materials for high temperature aircraft and rocket engine turbine applications. The W/Cu composite efforts are summarized, some of the results obtained are described, and an update is provided on more recent work using W/Cu composites as high strength, high thermal conductivity composite materials for high heat flux, elevated temperature applications.

Processing of micro-nano bacterial cellulose with hydrolysis method as a reinforcing bioplastic

NASA Astrophysics Data System (ADS)

Maryam, Maryam; Dedy, Rahmad; Yunizurwan, Yunizurwan

2017-01-01

Nanotechnology is the ability to create and manipulate atoms and molecules on the smallest of scales. Their size allows them to exhibit novel and significantly improved physical, chemical, biological properties, phenomena, and processes because of their size. The purpose of this research is obtaining micro-nano bacterial cellulose as reinforcing bioplastics. Bacterial cellulose (BC) was made from coconut water for two weeks. BC was dried and grinded. Bacterial cellulose was given purification process with NaOH 5% for 6 hours. Making the micro-nano bacterial cellulose with hydrolysis method. Hydrolysis process with hydrochloric acid (HCl) at the conditions 3,5M, 55°C, 6 hours. Drying process used spray dryer. The hydrolysis process was obtained bacterial cellulose with ±7 μm. The addition 2% micro-nano bacterial cellulose as reinforcing in bioplastics composite can improve the physical characteristics.

A comparison of tensile properties of polyester composites reinforced with pineapple leaf fiber and pineapple peduncle fiber

NASA Astrophysics Data System (ADS)

Juraidi, J. M.; Shuhairul, N.; Syed Azuan, S. A.; Intan Saffinaz Anuar, Noor

2013-12-01

Pineapple fiber which is rich in cellulose, relatively inexpensive, and abundantly available has the potential for polymer reinforcement. This research presents a study of the tensile properties of pineapple leaf fiber and pineapple peduncle fiber reinforced polyester composites. Composites were fabricated using leaf fiber and peduncle fiber with varying fiber length and fiber loading. Both fibers were mixed with polyester composites the various fiber volume fractions of 4, 8 and 12% and with three different fiber lengths of 10, 20 and 30 mm. The composites panels were fabricated using hand lay-out technique. The tensile test was carried out in accordance to ASTM D638. The result showed that pineapple peduncle fiber with 4% fiber volume fraction and fiber length of 30 mm give highest tensile properties. From the overall results, pineapple peduncle fiber shown the higher tensile properties compared to pineapple leaf fiber. It is found that by increasing the fiber volume fraction the tensile properties has significantly decreased but by increasing the fiber length, the tensile properties will be increased proportionally. Minitab software is used to perform the two-way ANOVA analysis to measure the significant. From the analysis done, there is a significant effect of fiber volume fraction and fiber length on the tensile properties.

SiC Fiber-Reinforced Celsian Composites

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

2003-01-01

Celsian is a promising matrix material for fiber-reinforced composites for high temperature structural applications. Processing and fabrication of small diameter multifilament silicon carbide tow reinforced celsian matrix composites are described. Mechanical and microstructural properties of these composites at ambient and elevated temperatures are presented. Effects of high-temperature exposures in air on the mechanical behavior of these composites are also given. The composites show mechanical integrity up to 1100 C but degrade at higher temperatures in oxidizing atmospheres. A model has been proposed for the degradation of these composites in oxidizing atmospheres at high temperatures.

Fiber-Reinforced Epoxy Composites and Methods of Making Same Without the Use of Oven or Autoclave

NASA Technical Reports Server (NTRS)

Barnell, Thomas J. (Inventor); Rauscher, Michael D. (Inventor); Stienecker, Rick D. (Inventor); Nickerson, David M. (Inventor); Tong, Tat H. (Inventor)

2016-01-01

Method embodiments for producing a fiber-reinforced epoxy composite comprise providing a mold defining a shape for a composite, applying a fiber reinforcement over the mold, covering the mold and fiber reinforcement thereon in a vacuum enclosure, performing a vacuum on the vacuum enclosure to produce a pressure gradient, insulating at least a portion of the vacuum enclosure with thermal insulation, infusing the fiber reinforcement with a reactive mixture of uncured epoxy resin and curing agent under vacuum conditions, wherein the reactive mixture of uncured epoxy resin and curing agent generates exothermic heat, and producing the fiber-reinforced epoxy composite having a glass transition temperature of at least about 100.degree. C. by curing the fiber reinforcement infused with the reactive mixture of uncured epoxy resin and curing agent by utilizing the exothermically generated heat, wherein the curing is conducted inside the thermally insulated vacuum enclosure without utilization of an external heat source or an external radiation source.

Evaluation of Fiber Reinforced Cement Using Digital Image Correlation

PubMed Central

Melenka, Garrett W.; Carey, Jason P.

2015-01-01

The effect of short fiber reinforcements on the mechanical properties of cement has been examined using a splitting tensile – digital image correlation (DIC) measurement method. Three short fiber reinforcement materials have been used in this study: fiberglass, nylon, and polypropylene. The method outlined provides a simple experimental setup that can be used to evaluate the ultimate tensile strength of brittle materials as well as measure the full field strain across the surface of the splitting tensile test cylindrical specimen. Since the DIC measurement technique is a contact free measurement this method can be used to assess sample failure. PMID:26039590

Fiber-reinforced composite fixed dental prostheses: two clinical reports.

PubMed

Zarow, Maciej; Paisley, Carl Stuart; Krupinski, Jerzy; Brunton, Paul Anthony

2010-06-01

Various options are available in clinical practice for the replacement of a single missing tooth, ranging from conventional fixed and removable dental prostheses to a single implant-supported crown. There are situations in which a semipermanent fixed dental prosthesis may be desirable, particularly for patients who have completed orthodontic treatment but are too young to embark on implant therapy. Following advances in fiber-reinforcement technology, fiber-reinforced composite resin (FRC) now represents a lower-cost alternative to traditional metal-ceramic for the construction of resin-bonded prostheses. Two case reports illustrate the use of FRC prostheses as fixed semipermanent_restorations.

Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

DOEpatents

Meek, T.T.; Blake, R.D.

1985-04-03

A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

DOEpatents

Meek, T.T.; Blake, R.D.

1987-09-22

A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate. 2 figs.

Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

DOEpatents

Meek, Thomas T.; Blake, Rodger D.

1987-01-01

A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

[Fiber reinforced composite posts: literature review].

PubMed

Frydman, G; Levatovsky, S; Pilo, R

2013-07-01

FRC (Fiber-reinforced composite) posts have been used since the beginning of the 90s with the introduction of carbon fiber posts. Fiber posts are widely used to restore endodontically treated teeth that have insufficient coronal tooth structure. Many in vitro and in vivo studies have shown the advantage of using FRC over prefabricated and cast metal post especially indicated in narrow root canals which are prone to vertically root fracture. The most frequent failure of FRC is debonding of a post at the resin cement/dentin interface. Bonding to dentin may be achieved by using etch-and-rinse and self-etch adhesives. The bond strength formed by self-adhesive cements is noticeably lower in comparison to the bond strength formed with resin cements applied in combination with etch-and-rinse adhesives. In an attempt to maximize resin bonding to fiber posts, several surface treatments have been suggested. Sandblasting with alumina particles results in an increased surface roughness and surface area without affecting the integrity of the post as long as it is applied by 50 microm alumina particles at 2.5 bars for maximally 5 seconds at a distance of 30 mm. The efficiency of post salinization is controversial and its contribution to the retention is of minor importance. Hydrofluoric acid has recently been proposed for etching glass fiber posts but this technique produced substantial damage to the glass fibers and affected the integrity of the post. Delayed cementation of fiber post (at least 24h post endodontic treatment) resulted in higher retentive strengths in comparison to immediate cementation and the best results were obtained when the luting agent was brought into the post space with lentulo spirals or specific syringes. The resin cement film thickness also influences the pullout strengths of fiber-reinforced posts .The highest bond strength values were obtained when the cement layer oversized the post spaces but not larger than 0.3 mm. The use of core build

Mechanical characterization of scalable cellulose nano-fiber based composites made using liquid composite molding process

Treesearch

Bamdad Barari; Thomas K. Ellingham; Issam I. Ghamhia; Krishna M. Pillai; Rani El-Hajjar; Lih-Sheng Turng; Ronald Sabo

2016-01-01

Plant derived cellulose nano-fibers (CNF) are a material with remarkable mechanical properties compared to other natural fibers. However, efforts to produce nano-composites on a large scale using CNF have yet to be investigated. In this study, scalable CNF nano-composites were made from isotropically porous CNF preforms using a freeze drying process. An improvised...

Impact toughness of cellulose-fiber reinforced polypropylene : influence of microstructure in laminates and injection molded composites

Treesearch

Craig Clemons; Daniel Caulfield; A. Jeffrey Giacomin

2003-01-01

Unlike their glass reinforced counterparts, microstructure and dynamic fracture behavior of natural fiber-reinforced thermoplastics have hardly been investigated. Here, we characterize the microstructure of cellulose fiber-reinforced polypropylene and determined its effect on impact toughness. Fiber lengths were reduced by one-half when compounded in a high-intensity...

Thermally sprayed prepregs for thixoforging of UD fiber reinforced light metal MMCs

NASA Astrophysics Data System (ADS)

Silber, Martin; Wenzelburger, Martin; Gadow, Rainer

2007-04-01

Low density and good mechanical properties are the basic requirements for lightweight structures in automotive and aerospace applications. With their high specific strength and strain to failure values, aluminum alloys could be used for such applications. Only the insufficient stiffness and thermal and fatigue strength prevented their usage in high-end applications. One possibility to solve this problem is to reinforce the light metal with unidirectional fibers. The UD fiber allows tailoring of the reinforcement to meet the direction of the component's load. In this study, the production of thermally sprayed prepregs for the manufacturing of continuous fiber reinforced MMC by thixoforging is analysed. The main aim is to optimize the winding procedure, which determines the fiber strand position and tension during the coating process. A method to wind and to coat the continuous fibers with an easy-to-use handling technique for the whole manufacturing process is presented. The prepregs were manufactured by producing arc wire sprayed AlSi6 coatings on fibers bundles. First results of bending experiments showed appropriate mechanical properties.

Composite Reinforcement by Magnetic Control of Fiber Density and Orientation.

PubMed

Goldberg, Omri; Greenfeld, Israel; Wagner, H Daniel

2018-05-08

The flexural rigidity of cylindrical specimens, composed of epoxy reinforced by short, magnetized glass fibers, was enhanced using weak magnetic fields (<100 mT). By spatially controlling the magnitude and direction of the field, and thereby the torques and forces acting locally on the fibers, the orientation and concentration of the fillers in the matrix could be tuned prior to curing. Unidirectional alignment of the fibers, achieved using an air-core solenoid, improved the contribution of the fibers to the flexure modulus by a factor of 3. When a ring-shaped permanent magnet was utilized, the glass fibers were migrated preferentially near the rod boundary, and as a result, the contribution of the fibers to the flexure modulus doubled. The fiber length, density, and orientation distributions were extracted by μCT image analysis, allowing comparison of the experimental flexure modulus to a modified rule of mixtures prediction. The ability to magnetically control the fiber distribution in reinforced composites demonstrated in this study may be applied in the fabrication of complex micro- and macroscale structures with spatially variable anisotropy, allowing features such as crack diversion, strengthening of highly loaded regions, as well as economic management of materials and weight.

Fiber reinforced polymer bridge decks : [technical summary].

DOT National Transportation Integrated Search

2011-01-01

A number of researchers have addressed the use of Fiber Reinforced Polymer (FRP) deck as a replacement solution for deteriorated bridge decks made of traditional materials. The use of new, advanced materials such as FRP is advantageous when the bridg...

Glass Fiber Reinforced Polymer Dowel Bar Evaluation

DOT National Transportation Integrated Search

2012-09-01

Glass Fiber Reinforced Polymer (GFRP) dowel bars were installed on one new construction project and two dowel bar : retrofit projects to evaluate the performance of this type of dowel bar in comparison to steel dowel bars installed on the same : cont...

Modification of glass fibers to improve reinforcement: a plasma polymerization technique.

PubMed

Cökeliler, Dilek; Erkut, Selim; Zemek, Josef; Biederman, Hynek; Mutlu, Mehmet

2007-03-01

This study evaluates the effect of plasma treated E-glass fiber to improve the mechanical properties of acrylic resin denture base material, polymethylmethacrlyate (PMMA). Plasma surface treatment of fibers is used as reinforcement in composite materials to modify the chemical and physical properties of their surfaces with tailored fiber-matrix bonding strength. Three different types of monomer 2-hydroxyethyl methacrylate (HEMA), triethyleneglycoldimethylether (TEGDME) and ethylenediamine (EDA) were used in the plasma polymerization modification of glass fibers. A radiofrequency generator was used to sustain plasma in a glass vacuum chamber. Glass fibers were modified at the same glow-discharge power of 25 W and exposure time of 30 min for each monomer. Fibers were incorporated into the acrylic with 1% (w/w) loading except control group. Specimens were prepared using a standard mold of 3 cmx0.5 cmx0.8 cm in dimension with eight specimens in each group. Samples were subjected to a flexural strength test set up at a crosshead speed of 5mm/min. Scanning electron microscopy (SEM) was used to examine the microstructure and X-ray photoelectron spectroscopy (XPS) was used for chemical analysis of the surface. Data were analyzed by means of ANOVA and Duncan's tests. Test results revealed that fiber reinforcement had a significant effect on the flexural strength of the specimens (p<0.05). Among the fiber reinforced groups, plasma treatment with EDA monomer resulted in the most significant increase in flexural strength values (p<0.05). XPS results have shown an increasing number of nitrogenous compounds in EDA treated fibers. The chemical structure of the surface, especially with the increase in nitrogenous compounds could give an idea for the amine film deposition and SEM figures showed an increase in surface roughness. The results showed that plasma treatment with EDA monomer was an effective alternative method of increasing the flexural strength of PMMA based denture base

Environmental Durability of Reinforced Concrete Deck Girders Strengthened for Shear with Surface-Bonded Carbon Fiber-Reinforced Polymer

DOT National Transportation Integrated Search

2009-05-01

"This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort...

Evaluation of long carbon fiber reinforced concrete to mitigate earthquake damage of infrastructure components.

DOT National Transportation Integrated Search

2013-06-01

The proposed study involves investigating long carbon fiber reinforced concrete as a method of mitigating earthquake damage to : bridges and other infrastructure components. Long carbon fiber reinforced concrete has demonstrated significant resistanc...

Mechanical Behavior of Steel Fiber-Reinforced Concrete Beams Bonded with External Carbon Fiber Sheets

PubMed Central

Gribniak, Viktor; Tamulenas, Vytautas; Ng, Pui-Lam; Arnautov, Aleksandr K.; Gudonis, Eugenijus; Misiunaite, Ieva

2017-01-01

This study investigates the mechanical behavior of steel fiber-reinforced concrete (SFRC) beams internally reinforced with steel bars and externally bonded with carbon fiber-reinforced polymer (CFRP) sheets fixed by adhesive and hybrid jointing techniques. In particular, attention is paid to the load resistance and failure modes of composite beams. The steel fibers were used to avoiding the rip-off failure of the concrete cover. The CFRP sheets were fixed to the concrete surface by epoxy adhesive as well as combined with various configurations of small-diameter steel pins for mechanical fastening to form a hybrid connection. Such hybrid jointing techniques were found to be particularly advantageous in avoiding brittle debonding failure, by promoting progressive failure within the hybrid joints. The use of CFRP sheets was also effective in suppressing the localization of the discrete cracks. The development of the crack pattern was monitored using the digital image correlation method. As revealed from the image analyses, with an appropriate layout of the steel pins, brittle failure of the concrete-carbon fiber interface could be effectively prevented. Inverse analysis of the moment-curvature diagrams was conducted, and it was found that a simplified tension-stiffening model with a constant residual stress level at 90% of the strength of the SFRC is adequate for numerically simulating the deformation behavior of beams up to the debonding of the CFRP sheets. PMID:28773024

Mechanical Behavior of Steel Fiber-Reinforced Concrete Beams Bonded with External Carbon Fiber Sheets.

PubMed

Gribniak, Viktor; Tamulenas, Vytautas; Ng, Pui-Lam; Arnautov, Aleksandr K; Gudonis, Eugenijus; Misiunaite, Ieva

2017-06-17

This study investigates the mechanical behavior of steel fiber-reinforced concrete (SFRC) beams internally reinforced with steel bars and externally bonded with carbon fiber-reinforced polymer (CFRP) sheets fixed by adhesive and hybrid jointing techniques. In particular, attention is paid to the load resistance and failure modes of composite beams. The steel fibers were used to avoiding the rip-off failure of the concrete cover. The CFRP sheets were fixed to the concrete surface by epoxy adhesive as well as combined with various configurations of small-diameter steel pins for mechanical fastening to form a hybrid connection. Such hybrid jointing techniques were found to be particularly advantageous in avoiding brittle debonding failure, by promoting progressive failure within the hybrid joints. The use of CFRP sheets was also effective in suppressing the localization of the discrete cracks. The development of the crack pattern was monitored using the digital image correlation method. As revealed from the image analyses, with an appropriate layout of the steel pins, brittle failure of the concrete-carbon fiber interface could be effectively prevented. Inverse analysis of the moment-curvature diagrams was conducted, and it was found that a simplified tension-stiffening model with a constant residual stress level at 90% of the strength of the SFRC is adequate for numerically simulating the deformation behavior of beams up to the debonding of the CFRP sheets.

Problems encountered with conventional fiber-reinforced composites

NASA Technical Reports Server (NTRS)

Landel, R. F.

1981-01-01

Preparational, computational, and operational problems associated with fiber-reinforced composites (FRC) are reviewed. Initial preparation of FRCs is shown to involve consideration of the type of prepreg, the setting time, cure conditions and cycles, and cure temperatures. The effects of the choice of bonding agents, the fiber transfer length, and individual fiber responses to bonding agents are noted to have an impact on fiber strength, moisture uptake, and fatigue resistance. The deformation prior to failure and the failure region are modeled through models of mini-, micro- and macro mechanics formulations employing a stiffness matrix, failure criterion, or fracture mechanics. The detection, evaluation, and repair of defects comprises the operational domain, and it is stressed that no good repair techniques exist for FRCs.

Nanofiber reinforcement of a geopolymer matrix for improved composite materials mechanical performance

NASA Astrophysics Data System (ADS)

Rahman, AKM Samsur

Geopolymers have the potential to cross the process performance gap between polymer matrix and ceramic matrix composites (CMC), enabling high temperature capable composites that are manufactured at relatively low temperatures. Unfortunately, the inherently low toughness of these geopolymers limits the performance of the resulting fiber reinforced geopolymer matrix composites. Toughness improvements in composites can be addressed through the adjustments in the fiber/matrix interfacial strength and through the improvements in the inherent toughness of the constituent materials. This study investigates the potential to improve the inherent toughness of the geopolymer matrix material through the addition of nanofillers, by considering physical dimensions, mechanical properties, reinforcing capability and interfacial bond strength effects. A process optimization study was first undertaken to develop the ability to produce consistent, neat geopolymer samples, a critical precursor to producing nano-filled geopolymer for toughness evaluation. After that, single edge notched bend beam fracture toughness and un-notched beam flexural strength were evaluated for silicon carbide, alumina and carbon nanofillers reinforced geopolymer samples treated at various temperatures in reactive and inert environments. Toughness results of silicon carbide and carbon nanofillers reinforced geopolymers suggested that with the improved baseline properties, high aspect ratio nanofillers with high interfacial bond strength are the most capable in further improving the toughness of geopolymers. Among the high aspect ratio nanofillers i.e. nanofibers, 2vol% silicon carbide whicker (SCW) showed the highest improvement in fracture toughness and flexural strength of ~164% & ~185%, respectively. After heat treatment at 650 °C, SCW reinforcement was found to be effective, with little reduction in the performance, while the performance of alumina nanofiber (ANF) reinforced geopolymer significantly

Dynamic properties of hydrogels and fiber-reinforced hydrogels.

PubMed

Martin, Nicholas; Youssef, George

2018-06-07

Hydrophilic polymers, or hydrogels, are used for a wide variety of biomedical applications, due to their inherent ability to withhold a high-water content. In recent years, a large effort has been focused on tailoring the mechanical properties of these hydrogels to become more appropriate materials for use as anatomical and physiological structural supports. A few of these such methods include using diverse types of polymers, both natural and synthetic, varying the type of molecular cross-linking, as well as combining these efforts to form interpenetrating polymer network hydrogels. While multiple research groups have characterized these various hydrogels under quasi-static conditions, their dynamic properties, representative of native physiological loading scenarios, have been scarcely reported. In this study, an E-glass fiber reinforced family of alginate/PAAm hydrogels cross-linked by both divalent and trivalent cations are fabricated and investigated. The effect of the reinforcement phase on the dynamic and hydration behaviors is then explicated. Additionally, a micromechanics framework for short cylindrical chopped fibers is utilized to discern the contribution of the matrix and fiber constituents on the hydrogel composite. The addition of E-glass fibers resulted in the storage modulus exhibiting a ~50%, 5%, and ~120%, increase with a mere addition of 2 wt% of the reinforcing fibers to Na-, Sr-, and Al-alginate/PAAm, respectively. In studying the cross-linking effect of various divalent (Ba, Ca, Sr) and trivalent (Al, Fe) cations, it was noteworthy that the hydrogels were found to be effective in dissipating energy while resisting mechanical deformation when they are cross-linked with higher molecular weight elements, regardless of valency. This report on the dynamic properties of these hydrogels will help to improve their optimization for future use in biomedical load-bearing applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mechanics of Bimodular Composite Structures.

DTIC Science & Technology

1982-07-01

and P. de Meester (1978). The mechanical behaviour of porous austenitic stainless steel fibre structure. J. Matls. Sci., 13, 2650-2658. Gilbert, G.N.J...Investigator Material EClEt Kotlarskii & Karbasova (1968) Fabric/rubber 0.38 Ducheyne et al. (1978) Sintered, porous 0.1 stainless steel Zolotukhina & Lepetov...with aramid cord than when reinforced with polyester cord, This is probably related to the very low compressive strength of the aramid fibers

Nonwoven glass fiber mat reinforces polyurethane adhesive

NASA Technical Reports Server (NTRS)

Roseland, L. M.

1967-01-01

Nonwoven glass fiber mat reinforces the adhesive properties of a polyurethane adhesive that fastens hardware to exterior surfaces of aluminum tanks. The mat is embedded in the uncured adhesive. It ensures good control of the bond line and increases the peel strength.

Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

NASA Astrophysics Data System (ADS)

Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

2015-01-01

Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

Structural characterization and mechanical properties of polypropylene reinforced natural fibers

NASA Astrophysics Data System (ADS)

Karim, M. A. A.; Zaman, I.; Rozlan, S. A. M.; Berhanuddin, N. I. C.; Manshoor, B.; Mustapha, M. S.; Khalid, A.; Chan, S. W.

2017-10-01

Recently the development of natural fiber composite instead of synthetics fiber has lead to eco-friendly product manufacturing to meet various applications in the field of automotive, construction and manufacturing. The use of natural fibers offer an alternative to the reinforcing fibers because of their good mechanical properties, low density, renewability, and biodegradability. In this present research, the effects of maleic anhydride polypropylene (MAPP) on the mechanical properties and material characterization behaviour of kenaf fiber and coir fiber reinforced polypropylene were investigated. Different fractions of composites with 10wt%, 20wt% and 30wt% fiber content were prepared by using brabender mixer at 190°C. The 3wt% MAPP was added during the mixing. The composites were subsequently molded with injection molding to prepare the test specimens. The mechanical properties of the samples were investigated according to ISO 527 to determine the tensile strength and modulus. These results were also confirmed by the SEM machine observations of fracture surface of composites and FTIR analysis of the chemical structure. As the results, the presence of MAPP helps increasing the mechanical properties of both fibers and 30wt% kenaf fiber with 3wt% MAPP gives the best result compare to others.

Characterization of Polyester Matrix Reinforced with Banana Fibers Thermal Properties by Photoacoustic Technique

NASA Astrophysics Data System (ADS)

de Assis, Foluke S.; Netto, Pedro A.; Margem, Frederico M.; Monteiro, Artur R. P. Junior Sergio N.

Synthetic fibers are being replaced gradually by natural materials such as lignocellulosic fibers. Compared to synthetic fibers, natural fibers have shown advantages in technical aspects such as environmental and economic. So there is a growing international interest in the use of those fibers. The banana fiber presents significant properties to be studied, but until now few thermal properties on banana fiber as reinforcement of polyester matrix were performed. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity for polyester composites reinforced with banana fibers. In the polyester matrix will be added up to 30% in volume of continuous and aligned banana fibers. These values show that the incorporation of banana fibers in the polyester matrix changes its thermal properties.

Nondestructive testing of externally reinforced structures for seismic retrofitting using flax fiber reinforced polymer (FFRP) composites

NASA Astrophysics Data System (ADS)

Ibarra-Castanedo, C.; Sfarra, S.; Paoletti, D.; Bendada, A.; Maldague, X.

2013-05-01

Natural fibers constitute an interesting alternative to synthetic fibers, e.g. glass and carbon, for the production of composites due to their environmental and economic advantages. The strength of natural fiber composites is on average lower compared to their synthetic counterparts. Nevertheless, natural fibers such as flax, among other bast fibers (jute, kenaf, ramie and hemp), are serious candidates for seismic retrofitting applications given that their mechanical properties are more suitable for dynamic loads. Strengthening of structures is performed by impregnating flax fiber reinforced polymers (FFRP) fabrics with epoxy resin and applying them to the component of interest, increasing in this way the load and deformation capacities of the building, while preserving its stiffness and dynamic properties. The reinforced areas are however prompt to debonding if the fabrics are not mounted properly. Nondestructive testing is therefore required to verify that the fabric is uniformly installed and that there are no air gaps or foreign materials that could instigate debonding. In this work, the use of active infrared thermography was investigated for the assessment of (1) a laboratory specimen reinforced with FFRP and containing several artificial defects; and (2) an actual FFRP retrofitted masonry wall in the Faculty of Engineering of the University of L'Aquila (Italy) that was seriously affected by the 2009 earthquake. Thermographic data was processed by advanced signal processing techniques, and post-processed by computing the watershed lines to locate suspected areas. Results coming from the academic specimen were compared to digital speckle photography and holographic interferometry images.

Fiber Reinforced Composite Cores and Panels

NASA Technical Reports Server (NTRS)

Day, Stephen W. (Inventor); Campbell, G. Scott (Inventor); Tilton, Danny E. (Inventor); Stoll, Frederick (Inventor); Sheppard, Michael (Inventor); Banerjee, Robin (Inventor)

2013-01-01

A fiber reinforced core panel is formed from strips of plastics foam helically wound with layers of rovings to form webs which may extend in a wave pattern or may intersect transverse webs. Hollow tubes may replace foam strips. Axial rovings cooperate with overlying helically wound rovings to form a beam or a column. Wound roving patterns may vary along strips for structural efficiency. Wound strips may alternate with spaced strips, and spacers between the strips enhance web buckling strength. Continuously wound rovings between spaced strips permit folding to form panels with reinforced edges. Continuously wound strips are helically wrapped to form annular structures, and composite panels may combine both thermoset and thermoplastic resins. Continuously wound strips or strip sections may be continuously fed either longitudinally or laterally into molding apparatus which may receive skin materials to form reinforced composite panels.

Uncertainty quantification of fiber orientation distribution measurements for long-fiber-reinforced thermoplastic composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Bhisham N.; Naragani, Diwakar; Nguyen, Ba Nghiep

Here, we present a detailed methodology for experimental measurement of fiber orientation distribution in injection-molded discontinuous fiber composites using the method of ellipses on two-dimensional cross sections. Best practices to avoid biases occurring during surface preparation and optical imaging of carbon-fiber-reinforced thermoplastics are discussed. We developed a marker-based watershed transform routine for efficient image segmentation and the separation of touching fiber ellipses. The sensitivity of the averaged orientation tensor to the image sample size is studied for the case of long-fiber thermoplastics. A Mori–Tanaka implementation of the Eshelby model is then employed to quantify the sensitivity of elastic stiffness predictionsmore » to biases in the fiber orientation distribution measurements.« less

Uncertainty quantification of fiber orientation distribution measurements for long-fiber-reinforced thermoplastic composites

DOE PAGES

Sharma, Bhisham N.; Naragani, Diwakar; Nguyen, Ba Nghiep; ...

2017-09-28

Here, we present a detailed methodology for experimental measurement of fiber orientation distribution in injection-molded discontinuous fiber composites using the method of ellipses on two-dimensional cross sections. Best practices to avoid biases occurring during surface preparation and optical imaging of carbon-fiber-reinforced thermoplastics are discussed. We developed a marker-based watershed transform routine for efficient image segmentation and the separation of touching fiber ellipses. The sensitivity of the averaged orientation tensor to the image sample size is studied for the case of long-fiber thermoplastics. A Mori–Tanaka implementation of the Eshelby model is then employed to quantify the sensitivity of elastic stiffness predictionsmore » to biases in the fiber orientation distribution measurements.« less

Design and analysis of a novel latch system implementing fiber-reinforced composite materials

NASA Astrophysics Data System (ADS)

Guevara Arreola, Francisco Javier

The use of fiber-reinforced composite materials have increased in the last four decades in high technology applications due to their exceptional mechanical properties and low weight. In the automotive industry carbon fiber have become popular exclusively in luxury cars because of its high cost. However, Carbon-glass hybrid composites offer an effective alternative to designers to implement fiber-reinforced composites into several conventional applications without a considerable price increase maintaining most of their mechanical properties. A door latch system is a complex mechanism that is under high loading conditions during car accidents such as side impacts and rollovers. Therefore, the Department of Transportation in The United States developed a series of tests that every door latch system comply in order to be installed in a vehicle. The implementation of fiber-reinforced composite materials in a door latch system was studied by analyzing the material behavior during the FMVSS No. 206 transverse test using computational efforts and experimental testing. Firstly, a computational model of the current forkbolt and detent structure was developed. Several efforts were conducted in order to create an effective and time efficient model. Two simplified models were implemented with two different contact interaction approaches. 9 composite materials were studied in forkbolt and 5 in detent including woven carbon fiber, unidirectional carbon fiber, woven carbon-glass fiber hybrid composites and unidirectional carbon-glass fiber hybrid composites. The computational model results showed that woven fiber-reinforced composite materials were stiffer than the unidirectional fiber-reinforced composite materials. For instance, a forkbolt made of woven carbon fibers was 20% stiffer than a forkbolt made of unidirectional fibers symmetrically stacked in 0° and 90° alternating directions. Furthermore, Hybrid composite materials behaved as expected in forkbolt noticing a decline

Characterization of the reaction products and precipitates at the interface of carbon fiber reinforced magnesium–gadolinium composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yaping; Jiang, Longtao, E-mail: longtaojiang@163.com; Chen, Guoqin

2016-03-15

In the present work, carbon fiber reinforced magnesium-gadolinium composite was fabricated by pressure infiltration method. The phase composition, micro-morphology, and crystal structure of reaction products and precipitates at the interface of the composite were investigated. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed the segregation of gadolinium element at the interface between carbon fiber and matrix alloy. It was shown that block-shaped Gd4C5, GdC2 and nano-sized Gd2O3 were formed at the interface during the fabrication process due to the interfacial reaction. Furthermore, magnesium-gadolinium precipitates including needle-like Mg5Gd (or Mg24Gd5) and thin plate-shaped long period stacking-ordered phase, were also observedmore » at the interface and in the matrix near the interface. The interfacial microstructure and bonding mode were influenced by these interfacial products, which were beneficial for the improvement of the interfacial bonding strength. - Highlights: • Gadolinium element segregated on the surface of carbon fibers. • Block-shaped Gd{sub 4}C{sub 5} and GdC{sub 2} were formed at the interface via chemical reaction. • Gadolinium and oxygen reacted at the interface and formed nano-scaled Gd{sub 2}O{sub 3}. • The precipitates formed in the interface were identified to be Mg{sub 5}Gd (or Mg{sub 24}Gd{sub 5}) and plate-shaped long period stacking-ordered phase.« less

Low Velocity Impact Behavior of Basalt Fiber-Reinforced Polymer Composites

NASA Astrophysics Data System (ADS)

Shishevan, Farzin Azimpour; Akbulut, Hamid; Mohtadi-Bonab, M. A.

2017-06-01

In this research, we studied low velocity impact response of homogenous basalt fiber-reinforced polymer (BFRP) composites and then compared the impact key parameters with carbon fiber-reinforced polymer (CFRP) homogenous composites. BFRPs and CFRPs were fabricated by vacuum-assisted resin transfer molding (VARTM) method. Fabricated composites included 60% fiber and 40% epoxy matrix. Basalt and carbon fibers used as reinforcement materials were weaved in 2/2 twill textile tip in the structures of BFRP and CFRP composites. We also utilized the energy profile method to determine penetration and perforation threshold energies. The low velocity impact tests were carried out in 30, 60, 80, 100, 120 and 160 J energy magnitudes, and impact response of BFRPs was investigated by related force-deflection, force-time, deflection-time and absorbed energy-time graphics. The related impact key parameters such as maximum contact force, absorbed energy, deflection and duration time were compared with CFRPs for various impact energy levels. As a result, due to the higher toughness of basalt fibers, a better low velocity impact performance of BFRP than that of CFRP was observed. The effects of fabrication parameters, such as curing process, were studied on the low velocity impact behavior of BFRP. The results of tested new fabricated materials show that the change of fabrication process and curing conditions improves the impact behavior of BFRPs up to 13%.

Uncertainty quantification of fiber orientation distribution measurements for long-fiber-reinforced thermoplastic composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Bhisham N.; Naragani, Diwakar; Nguyen, Ba Nghiep

We present a detailed methodology for experimental measurement of fiber orientation distribution (FOD) in injection-molded discontinuous fiber composites using the method of ellipses on 2D cross sections. Best practices to avoid biases occurring during surface preparation and optical imaging of carbon-fiber-reinforced thermoplastics are discussed. A marker-based watershed transform routine for efficient image segmentation and the separation of touching fiber ellipses is developed. The sensitivity of the averaged orientation tensor to the image sample size is studied for the case of long-fiber thermoplastics. A Mori-Tanaka implementation of the Eshelby model is then employed to quantify the sensitivity of elastic stiffness predictionsmore » to biases in the FOD measurements.« less

[Fiber-reinforced composite in fixed prosthodontics].

PubMed

Pilo, R; Abu Rass, Z; Shmidt, A

2010-07-01

Fiber reinforced composite (FRC) is composed of resin matrix and fibers filler. Common types of fibers: polyethylene, carbon and glass. Fibers can be continuous and aligned, discontinuous and aligned, discontinuous and randomly oriented. The architecture of the fibers is unidirectional, woven or braided. The two main types are: dry fibers or impregnated. Inclusion of fibers to resin composite increased its average flexural strength in 100-200 MPa. FRC can be utilized by the dentist in direct approach (splinting, temporary winged bridge) or indirect approach (laboratory made fixed partial denture). Laboratory fixed partial denture (FPD) is made from FRC substructure and Hybrid/Microfill particulate composite veneer. Main indications: interim temporary FPD or FPD in cases of questionable abutment teeth, in aesthetic cases where All Ceram FPD is not feasible. Retention is attained by adhesive cementation to minimally prepared teeth or to conventionally prepared teeth; other options are inlay-onlay bridges or hybrid bridges. Contraindications are: poor hygiene, inability to control humidity, parafunction habits, and more than two pontics. Survival rate of FRC FPD over 5 years is 75%, lower compared to porcelain fused to metal FPD which is 95%. Main reasons for failure are: fracture of framework and delamination of the veneer. Part of the failures is repairable.

Effectiveness of Fiber Reinforcement on the Mechanical Properties and Shrinkage Cracking of Recycled Fine Aggregate Concrete.

PubMed

Nam, Jeongsoo; Kim, Gyuyong; Yoo, Jaechul; Choe, Gyeongcheol; Kim, Hongseop; Choi, Hyeonggil; Kim, Youngduck

2016-02-26

This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber-polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimum quantity. Additionally, to make a comparative evaluation of the mechanical properties and shrinkage cracking, we examined natural fine aggregate concrete as well. The test results revealed that the addition of fibers and fine aggregates plays an important role in improving the mechanical performance of the investigated concrete specimens as well as controlling their cracking behavior. The mechanical properties such as compressive strength, splitting tensile strength, and flexural strength of fiber-reinforced RFAC were slightly better than those of non-fiber-reinforced RFAC. The shrinkage cracking behavior was examined using plat-ring-type and slab-type tests. The fiber-reinforced RFAC showed a greater reduction in the surface cracks than non-fiber-reinforced concrete. The addition of fibers at a small volume fraction in RFAC is more effective for drying shrinkage cracks than for improving mechanical performance.

Polymer concrete reinforced with recycled-tire fibers: Mechanical properties

NASA Astrophysics Data System (ADS)

Martínez-Cruz, E.; Martínez-Barrera, G.; Martínez-López, M.

2013-06-01

Polymer Concrete was reinforced with recycled-tire fibers in order to improve the compressive and flexural strength. Polymer concrete specimens were prepared with 70% of silicious sand, 30% of polyester resin and various fiber concentrations (0.3, 0.6, 0.9 and 1.2 vol%). The results show increment of 50% in average of the compressive and flexural strength as well as on the deformation when adding 1.2 vol% of recycled-fibers.

Facile Fabrication of Multifunctional Aramid Nanofiber Films by Spin Coating

NASA Astrophysics Data System (ADS)

Lyu, Jing; Liu, Lehao; Zhao, Xing; Shang, Yudong; Zhao, Tingkai; Li, Tiehu

2016-11-01

Polymer matrices with excellent mechanical properties, thermal stability and other features are highly demanded for the effective utilization within nanocomposites. Here, we fabricate free-standing aramid nanofiber films via spin coating of an aramid nanofiber/dimethyl sulfoxide solution. Compared with traditional film fabrication methods, this process is time-saving and also able to easily tune the thickness of the films. The resultant films show greatly improved stretchability than that of Kevlar threads and relatively high mechanical strength. Typically, these films with a thickness of 5.5 µm show an ultimate strength of 182 MPa with an ultimate tensile strain of 10.5%. We also apply a finite element modeling to simulate the strain and strength distributions of the films under uniaxial tension, and the results of the simulation are in accordance with the experimental data. Furthermore, the aramid nanofiber films exhibit outstanding thermostability (decomposition at 550 °C under N2 atmosphere and 500 °C in air) and chemical inertness, which would endure acid and alkali. The simple method demonstrated here provides an important way to prepare high-performance aramid nanofiber films for designing new composite systems.

Method for Cleaning Laser-Drilled Holes on Printed Wiring Boards by Plasma Treatment

NASA Astrophysics Data System (ADS)

Hirogaki, Toshiki; Aoyama, Eiichi; Minagi, Ryu; Ogawa, Keiji; Katayama, Tsutao; Matsuoka, Takashi; Inoue, Hisahiro

We propose a new method for cleaning blind via holes after laser drilling of PWBs using oxygen plasma treatment. This report dealt with three kinds of PWB materials: epoxy resin and two kinds of aramid fiber reinforced plastics (AFRP: Technora or Kevlar fiber reinforcement). We observed the drilled holes after plasma treatment using both an optical and a scanning electric microscope (SEM). It was confirmed that adequate etching took place in the drilled holes by plasma treatment. We also compared the hole wall and hole bottom after plasma treatment with ones after chemical etching. It was clear that there was no damage to the aramid fiber tip on the hole wall, and that a smooth roughness of the hole wall was obtained by means of plasma treatment. As a result, we demonstrated that the plasma treatment is effective in cleaning the laser drilled holes of PWBs.

Latex modified fiber reinforced concrete bridge deck overlay : final report.

DOT National Transportation Integrated Search

1995-11-01

In an attempt to increase the tensile strength of LMC and reduce cracking, steel fibers were added to a LMC mix. The results are what is termed as "latex-modified, fiber-reinforced concrete" (LMFRC). LMFRC was placed on Hayden Bridge as an experiment...

Short cellulose nanofribrils as reinforcement in polyvinyl alcohol fiber

Treesearch

Jun Peng; Thomas Ellingham; Ron Sabo; Lih-Sheng Turng; Craig M. Clemons

2014-01-01

Short cellulose nanofibrils (SCNF) were investigated as reinforcement for polyvinyl alcohol (PVA) fibers. SCNF were mechanically isolated from hard wood pulp after enzymatic pretreatment. Various levels of SCNF were added to an aqueous PVA solution, which was gel-spun into continuous fibers. The molecular orientation of PVA was affected by a combination of wet drawing...

Study on Mechanical Properties of Hybrid Fiber Reinforced Concrete

NASA Astrophysics Data System (ADS)

He, Dongqing; Wu, Min; Jie, Pengyu

2017-12-01

Several common high elastic modulus fibers (steel fibers, basalt fibers, polyvinyl alcohol fibers) and low elastic modulus fibers (polypropylene fiber) are incorporated into the concrete, and its cube compressive strength, splitting tensile strength and flexural strength are studied. The test result and analysis demonstrate that single fiber and hybrid fiber will improve the integrity of the concrete at failure. The mechanical properties of hybrid steel fiber-polypropylene fiber reinforced concrete are excellent, and the cube compressive strength, splitting tensile strength and flexural strength respectively increase than plain concrete by 6.4%, 3.7%, 11.4%. Doped single basalt fiber or polypropylene fiber and basalt fibers hybrid has little effect on the mechanical properties of concrete. Polyvinyl alcohol fiber and polypropylene fiber hybrid exhibit ‘negative confounding effect’ on concrete, its splitting tensile and flexural strength respectively are reduced by 17.8% and 12.9% than the single-doped polyvinyl alcohol fiber concrete.

Dielectric strength of irradiated fiber reinforced plastics

NASA Astrophysics Data System (ADS)

Humer, Karl; Weber, Harald W.; Hastik, Ronald; Hauser, Hans; Gerstenberg, Heiko

2001-05-01

The insulation system for the toroidal field model coil of international thermonuclear experimental reactor is a fiber reinforced plastic (FRP) laminate, which consists of a combined Kapton/R-glass-fiber reinforcement tape, vacuum-impregnated with an epoxy DGEBA system. Pure disk-shaped laminates, disk-shaped FRP/stainless-steel sandwiches, and conductor insulation prototypes were irradiated at 5 K in a fission reactor up to a fast neutron fluence of 10 22 m -2 ( E>0.1 MeV) to investigate the radiation induced degradation of the dielectric strength of the insulation system. After warm-up to room temperature, swelling, weight loss, and the breakdown strength were measured at 77 K. The sandwich swells by 4% at a fluence of 5×10 21 m -2 and by 9% at 1×10 22 m -2. The weight loss of the FRP is 2% at 1×10 22 m -2. The dielectric strength remained unchanged over the whole dose range.

Selected Bibliography on Fiber-Reinforced Cement and Concrete. Supplement number 1.

DTIC Science & Technology

1977-09-01

A listing of 156 additional references with author index is given for fiber-reinforced cement and gypsum matrices, mortars, and concretes. Fiber types include steel, glass, plastic, asbestos, organic, carbon, and others. (Author)

Selected Bibliography on Fiber-Reinforced Cement and Concrete. Supplement Number 2.

DTIC Science & Technology

1979-07-01

A listing of 471 additional references with author index is given for fiber-reinforced cement and gypsum matrices, mortars, and concretes. Fiber types include steel, glass, plastic, asbestos, organic, carbon, and others. (Author)

Effectiveness of Fiber Reinforcement on the Mechanical Properties and Shrinkage Cracking of Recycled Fine Aggregate Concrete

PubMed Central

Nam, Jeongsoo; Kim, Gyuyong; Yoo, Jaechul; Choe, Gyeongcheol; Kim, Hongseop; Choi, Hyeonggil; Kim, Youngduck

2016-01-01

This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber—polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimum quantity. Additionally, to make a comparative evaluation of the mechanical properties and shrinkage cracking, we examined natural fine aggregate concrete as well. The test results revealed that the addition of fibers and fine aggregates plays an important role in improving the mechanical performance of the investigated concrete specimens as well as controlling their cracking behavior. The mechanical properties such as compressive strength, splitting tensile strength, and flexural strength of fiber-reinforced RFAC were slightly better than those of non-fiber-reinforced RFAC. The shrinkage cracking behavior was examined using plat-ring-type and slab-type tests. The fiber-reinforced RFAC showed a greater reduction in the surface cracks than non-fiber-reinforced concrete. The addition of fibers at a small volume fraction in RFAC is more effective for drying shrinkage cracks than for improving mechanical performance. PMID:28773256

Development and characterization of nano-fiber patch for the treatment of glaucoma.

PubMed

Gagandeep; Garg, Tarun; Malik, Basant; Rath, Goutam; Goyal, Amit K

2014-03-12

In the present work polymeric nano-fiber patches was developed for the effective treatment of glaucoma using timolol maleate and dorzolamide hydrochloride as model drugs. The nano-fibers were prepared by electrospinning technique and were characterized on the basis of fiber diameter, morphology, entrapment efficiency, mucoadhesive strength, and drug release behavior, etc. Final formulations were inserted in the cul-de-sac of glaucoma induced rabbits and the efficacy of the formulation was evaluated. The results clearly indicated the potential of the developed formulation for occur drug delivery. There was a significant fall in the intraocular pressure compared to commercial eye drops. Copyright © 2013 Elsevier B.V. All rights reserved.

Reactive processing of textile-natural fiber reinforced anionic polyamide-6 composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kan, Ze; Chen, Peng; Liu, Zhengying

Nowadays natural fiber, used in reinforced composites, is widely concerned. However, no natural fiber reinforced reactive thermoplastic polymer grades had been prepared so far. Through our studies, it was demonstrated that there was a severe retardation and discoloration occurred in the reactive processing between anionic polyamide-6 (APA-6) and natural fiber, which result in incomplete polymerization when put together. In order to solve the problem, two methods were adopted in this paper, which are fiber pretreatment and usage of a new-style initiator called caprolactam magnesium bromide. The former is to remove sizing agent and impurities on the surface of fiber, andmore » the latter is to weaken the side reactions between APA-6 and natural fiber by the nature of its lower reactivity and weaker alkaline. In cooperation with both methods, the severe retardation and discoloration had been improved significantly, so that the polymerization of APA-6 in natural fiber was occurred smoothly. Following textile-natural fiber reinforced APA-6 composites with an average thickness of 2.5 mm and a fiber volume content of 50% was prepared by vacuum assisted resin transfer molding (VARTM). The soxhlet extraction, dilute solution viscometry and differential scanning calorimeter (DSC) measurements respectively suggested the degree of conversion, viscosity-average molar mass and crystallization of composites was up to 94%, 11.3×104 and 50%. Remarkable improvement of mechanical properties were achieved through dynamic mechanical analysis (DMA), tensile and three-point bending test. Favorable interfacial adhesion and wettability were revealed by scanning electron microscopy (SEM) observation. Therefore, all of the above good performance make this new-style and environmentally friendly composites have broad application prospects.« less

Reactive processing of textile-natural fiber reinforced anionic polyamide-6 composites

NASA Astrophysics Data System (ADS)

Kan, Ze; Chen, Peng; Liu, Zhengying; Feng, Jianmin; Yang, Mingbo

2015-05-01

Nowadays natural fiber, used in reinforced composites, is widely concerned. However, no natural fiber reinforced reactive thermoplastic polymer grades had been prepared so far. Through our studies, it was demonstrated that there was a severe retardation and discoloration occurred in the reactive processing between anionic polyamide-6 (APA-6) and natural fiber, which result in incomplete polymerization when put together. In order to solve the problem, two methods were adopted in this paper, which are fiber pretreatment and usage of a new-style initiator called caprolactam magnesium bromide. The former is to remove sizing agent and impurities on the surface of fiber, and the latter is to weaken the side reactions between APA-6 and natural fiber by the nature of its lower reactivity and weaker alkaline. In cooperation with both methods, the severe retardation and discoloration had been improved significantly, so that the polymerization of APA-6 in natural fiber was occurred smoothly. Following textile-natural fiber reinforced APA-6 composites with an average thickness of 2.5 mm and a fiber volume content of 50% was prepared by vacuum assisted resin transfer molding (VARTM). The soxhlet extraction, dilute solution viscometry and differential scanning calorimeter (DSC) measurements respectively suggested the degree of conversion, viscosity-average molar mass and crystallization of composites was up to 94%, 11.3×104 and 50%. Remarkable improvement of mechanical properties were achieved through dynamic mechanical analysis (DMA), tensile and three-point bending test. Favorable interfacial adhesion and wettability were revealed by scanning electron microscopy (SEM) observation. Therefore, all of the above good performance make this new-style and environmentally friendly composites have broad application prospects.

Evaluation of mechanical properties of hybrid fiber (hemp, jute, kevlar) reinforced composites

NASA Astrophysics Data System (ADS)

Suresha, K. V.; Shivanand, H. K.; Amith, A.; Vidyasagar, H. N.

2018-04-01

In today's world composites play wide role in all the engineering fields. The reinforcement of composites decides the properties of the material. Natural fiber composites compared to synthetic fiber possesses poor mechanical properties. The solution for this problem is to use combination of natural fiber and synthetic fiber. Hybridization helps to improve the overall mechanical properties of the material. In this study, hybrid reinforced composites of Hemp fabric/Kevlar fabric/Epoxy and Jute fabric/ Kevlar fabric/Epoxy composites are fabricated using Simple hand layup technique followed by Vacuum bagging process. Appropriate test methods as per standards and guidelines are followed to analyze mechanical behavior of the composites. The mechanical characteristics like tensile, compression and flexural properties of the hybrid reinforced composites are tested as per the ASTM standards by series of tensile test; compression test and three point bending tests were conducted on the hybrid composites. A quantitative relationship between the Hemp fabric/Kevlar fabric/Epoxy and Jute/ Kevlar fabric/Epoxy has been established with constant thickness.

How Properties of Kenaf Fibers from Burkina Faso Contribute to the Reinforcement of Earth Blocks

PubMed Central

Millogo, Younoussa; Aubert, Jean-Emmanuel; Hamard, Erwan; Morel, Jean-Claude

2015-01-01

Physicochemical characteristics of Hibiscus cannabinus (kenaf) fibers from Burkina Faso were studied using X-ray diffraction (XRD), infrared spectroscopy, thermal gravimetric analysis (TGA), chemical analysis and video microscopy. Kenaf fibers (3 cm long) were used to reinforce earth blocks, and the mechanical properties of reinforced blocks, with fiber contents ranging from 0.2 to 0.8 wt%, were investigated. The fibers were mainly composed of cellulose type I (70.4 wt%), hemicelluloses (18.9 wt%) and lignin (3 wt%) and were characterized by high tensile strength (1 ± 0.25 GPa) and Young’s modulus (136 ± 25 GPa), linked to their high cellulose content. The incorporation of short fibers of kenaf reduced the propagation of cracks in the blocks, through the good adherence of fibers to the clay matrix, and therefore improved their mechanical properties. Fiber incorporation was particularly beneficial for the bending strength of earth blocks because it reinforces these blocks after the failure of soil matrix observed for unreinforced blocks. Blocks reinforced with such fibers had a ductile tensile behavior that made them better building materials for masonry structures than unreinforced blocks.

A micromorphic model for steel fiber reinforced concrete.

PubMed

Oliver, J; Mora, D F; Huespe, A E; Weyler, R

2012-10-15

A new formulation to model the mechanical behavior of high performance fiber reinforced cement composites with arbitrarily oriented short fibers is presented. The formulation can be considered as a two scale approach, in which the macroscopic model, at the structural level, takes into account the mesostructural phenomenon associated with the fiber-matrix interface bond/slip process. This phenomenon is contemplated by including, in the macroscopic description, a micromorphic field representing the relative fiber-cement displacement. Then, the theoretical framework, from which the governing equations of the problem are derived, can be assimilated to a specific case of the material multifield theory. The balance equation derived for this model, connecting the micro stresses with the micromorphic forces, has a physical meaning related with the fiber-matrix bond slip mechanism. Differently to previous procedures in the literature, addressed to model fiber reinforced composites, where this equation has been added as an additional independent ingredient of the methodology, in the present approach it arises as a natural result derived from the multifield theory. Every component of the composite is defined with a specific free energy and constitutive relation. The mixture theory is adopted to define the overall free energy of the composite, which is assumed to be homogeneously constituted, in the sense that every infinitesimal volume is occupied by all the components in a proportion given by the corresponding volume fraction. The numerical model is assessed by means of a selected set of experiments that prove the viability of the present approach.

Compostability assessment of nano-reinforced poly(lactic acid) films.

PubMed

Balaguer, M P; Aliaga, C; Fito, C; Hortal, M

2016-02-01

Nanomaterials can provide plastics with great advantages on mechanical and active properties (i.e. release and capture of specific substances). Therefore, packaging is expected to become one of the leading applications for these substances by 2020. There are some applications already in the market. Nevertheless, there is still some areas under development. A key issue to be analyzed is the end-of-life of these materials once they become waste, and specifically when nanomaterials are used in biodegradable products. The present study evaluated the disintegration, biodegradability, and ecotoxicity of poly(lactic acid) films reinforced with the three following nanomaterials: (1) montmorillonite modified with an ammonium quaternary salt, (2) calcium carbonate and (3) silicon dioxide. Results on disintegration showed that films completely disintegrated into visually indistinguishable residues after 6-7weeks of incubation in composting environment. Moreover, no differences were observed in the evolution of the bioresidue with respect to color, aspect, and odor in comparison with the control. It was also observed that nanomaterials did not significantly reduce the level of biodegradability of PLA (p>0.05). In fact, biodegradation was higher, without finding significant differences (p>0.05), in all the nano-reinforced samples with respect to PLA after 130days in composting (9.4% in PLA+Nano-SiO2; 34.0% in PLA+Clay1; 48.0% in PLA+Nano-CaCO3). Finally, no significant differences (p>0.05) in ecotoxicity in plants were observed as a result of the incorporation of nanoparticles in the PLA matrix. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mechanical and physical properties of carbon-graphite fiber-reinforced polymers intended for implant suprastructures.

PubMed

Segerström, Susanna; Ruyter, I Eystein

2007-09-01

Mechanical properties and quality of fiber/matrix adhesion of poly(methyl methacrylate) (PMMA)-based materials, reinforced with carbon-graphite (CG) fibers that are able to remain in a plastic state until polymerization, were examined. Tubes of cleaned braided CG fibers were treated with a sizing resin. Two resin mixtures, resin A and resin B, stable in the fluid state and containing different cross-linking agents, were reinforced with CG fiber loadings of 24, 36, and 47 wt% (20, 29, and 38 vol.%). In addition, resin B was reinforced with 58 wt% (47 vol.%). After heat-polymerization, flexural strength and modulus were evaluated, both dry and after water storage. Coefficient of thermal expansion, longitudinally and in the transverse direction of the specimens, was determined. Adhesion between fibers and matrix was evaluated with scanning electron microscopy (SEM). Flexural properties and linear coefficient of thermal expansion were similar for both fiber composites. With increased fiber loading, flexural properties increased. For 47 wt% fibers in polymer A the flexural strength was 547.7 (28.12) MPa and for polymer B 563.3 (89.24) MPa when water saturated. Linear coefficient of thermal expansion was for 47 wt% CG fiber-reinforced polymers; -2.5 x 10(-6) degrees C-1 longitudinally and 62.4 x 10(-6) degrees C-1 in the transverse direction of the specimens. SEM revealed good adhesion between fibers and matrix. More porosity was observed with fiber loading of 58 wt%. The fiber treatment and the developed resin matrices resulted in good adhesion between CG fibers and matrix. The properties observed indicate a potential for implant-retained prostheses.

Progressive Fracture and Damage Tolerance of Composite Pressure Vessels

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Gotsis, Pascal K.; Minnetyan, Levon

1997-01-01

Structural performance (integrity, durability and damage tolerance) of fiber reinforced composite pressure vessels, designed for pressured shelters for planetary exploration, is investigated via computational simulation. An integrated computer code is utilized for the simulation of damage initiation, growth, and propagation under pressure. Aramid fibers are considered in a rubbery polymer matrix for the composite system. Effects of fiber orientation and fabrication defect/accidental damages are investigated with regard to the safety and durability of the shelter. Results show the viability of fiber reinforced pressure vessels as damage tolerant shelters for planetary colonization.

A dendrite-suppressing composite ion conductor from aramid nanofibres.

PubMed

Tung, Siu-On; Ho, Szushen; Yang, Ming; Zhang, Ruilin; Kotov, Nicholas A

2015-01-27

Dendrite growth threatens the safety of batteries by piercing the ion-transporting separators between the cathode and anode. Finding a dendrite-suppressing material that combines high modulus and high ionic conductance has long been considered a major technological and materials science challenge. Here we demonstrate that these properties can be attained in a composite made from Kevlar-derived aramid nanofibres assembled in a layer-by-layer manner with poly(ethylene oxide). Importantly, the porosity of the membranes is smaller than the growth area of the dendrites so that aramid nanofibres eliminate 'weak links' where the dendrites pierce the membranes. The aramid nanofibre network suppresses poly(ethylene oxide) crystallization detrimental for ion transport, giving a composite that exhibits high modulus, ionic conductivity, flexibility, ion flux rates and thermal stability. Successful suppression of hard copper dendrites by the composite ion conductor at extreme discharge conditions is demonstrated, thereby providing a new approach for the materials engineering of solid ion conductors.

A dendrite-suppressing composite ion conductor from aramid nanofibres

NASA Astrophysics Data System (ADS)

Tung, Siu-On; Ho, Szushen; Yang, Ming; Zhang, Ruilin; Kotov, Nicholas A.

2015-01-01

Dendrite growth threatens the safety of batteries by piercing the ion-transporting separators between the cathode and anode. Finding a dendrite-suppressing material that combines high modulus and high ionic conductance has long been considered a major technological and materials science challenge. Here we demonstrate that these properties can be attained in a composite made from Kevlar-derived aramid nanofibres assembled in a layer-by-layer manner with poly(ethylene oxide). Importantly, the porosity of the membranes is smaller than the growth area of the dendrites so that aramid nanofibres eliminate ‘weak links’ where the dendrites pierce the membranes. The aramid nanofibre network suppresses poly(ethylene oxide) crystallization detrimental for ion transport, giving a composite that exhibits high modulus, ionic conductivity, flexibility, ion flux rates and thermal stability. Successful suppression of hard copper dendrites by the composite ion conductor at extreme discharge conditions is demonstrated, thereby providing a new approach for the materials engineering of solid ion conductors.

Experimental evaluation and simulation of volumetric shrinkage and warpage on polymeric composite reinforced with short natural fibers

NASA Astrophysics Data System (ADS)

Santos, Jonnathan D.; Fajardo, Jorge I.; Cuji, Alvaro R.; García, Jaime A.; Garzón, Luis E.; López, Luis M.

2015-09-01

A polymeric natural fiber-reinforced composite is developed by extrusion and injection molding process. The shrinkage and warpage of high-density polyethylene reinforced with short natural fibers of Guadua angustifolia Kunth are analyzed by experimental measurements and computer simulations. Autodesk Moldflow® and Solid Works® are employed to simulate both volumetric shrinkage and warpage of injected parts at different configurations: 0 wt.%, 20 wt.%, 30 wt.% and 40 wt.% reinforcing on shrinkage and warpage behavior of polymer composite. Become evident the restrictive effect of reinforcing on the volumetric shrinkage and warpage of injected parts. The results indicate that volumetric shrinkage of natural composite is reduced up to 58% with fiber increasing, whereas the warpage shows a reduction form 79% to 86% with major fiber content. These results suggest that it is a highly beneficial use of natural fibers to improve the assembly properties of polymeric natural fiber-reinforced composites.

Proof testing a bridge deck design with glass fiber reinforced polymer bars as top mat of reinforcement.

DOT National Transportation Integrated Search

2003-01-01

The primary objective of this project was to test a full-scale prototype of a bridge deck design containing glass fiber reinforced polymer (GFRP) bars as the top mat of reinforcement. The test deck mimics the design of the deck of one span of the new...

A strategy for prediction of the elastic properties of epoxy-cellulose nanocrystal-reinforced fiber networks

Treesearch

Johnathan E. Goodsell; Robert J. Moon; Alionso Huizar; R. Byron Pipes

2014-01-01

The reinforcement potential of cellulose nanocrystal (CNC) additions on an idealized 2-dirmensional (2-D) fiber network structure consisting of micron sized fiber elements was investigated. The reinforcement mechanism considered in this study was through the stiffening of the micron sized fiber elements via a CNC-epoxy coating. A hierarchical analytical modeling...

Tensile Mechanical Property of Oil Palm Empty Fruit Bunch Fiber Reinforced Epoxy Composites

NASA Astrophysics Data System (ADS)

Ghazilan, A. L. Ahmad; Mokhtar, H.; Shaik Dawood, M. S. I.; Aminanda, Y.; Ali, J. S. Mohamed

2017-03-01

Natural, short, untreated and randomly oriented oil palm empty fruit bunch fiber reinforced epoxy composites were manufactured using vacuum bagging technique with 20% fiber volume composition. The performance of the composite was evaluated as an alternative to synthetic or conventional reinforced composites. Tensile properties such as tensile strength, modulus of elasticity and Poisson’s ratio were compared to the tensile properties of pure epoxy obtained via tensile tests as per ASTM D 638 specifications using Universal Testing Machine INSTRON 5582. The tensile properties of oil palm empty fruit bunch fiber reinforced epoxy composites were lower compared to plain epoxy structure with the decrement in performances of 38% for modulus of elasticity and 61% for tensile strength.

New Fiber Reinforced Waterless Concrete for Extraterrestrial Structural Applications

NASA Technical Reports Server (NTRS)

Toutanji, H.; Tucker, D.; Ethridge, E.

2005-01-01

Commercial use of sulfur concrete on Earth is well established, particularly in corrosive, e.g., acid and salt, environments. Having found troilite (FeS) on the Moon raises the question of using extracted sulfur as a lunar construction mate: iii an attractive alternative to conventional concrete as it does not require water For the purpose of this paper it is assumed that lunar ore is mined, refined, and the raw sulfur processed with appropriate lunar regolith to form, for example, brick and beam elements. Glass fibers produced from regolith were used as a reinforcement to improve the mechanical properties of the sulfur concrete. Glass fibers and glass rebar were produced by melting the lunar regolith simulant. Lunar regolith stimulant was melted in a 25 cc Pt-Rh crucible in a Sybron Thermoline 46100 high temperature MoSi2 furnace at melting temperatures of 1450 to 1600G. The glass melt wets the ceramic rod and long continuous glass fibers were easily hand drawn. The glass fibers were immediately coated with a protective polymer to maintain the mechanical strength. The viability of sulfur concrete as a construction material for extraterrestrial application is presented. The mechanical properties of the glass fiber reinforced sulfur concrete were investigated.

Influence of injection molding process parameters on fiber concentration distribution in long glass fiber reinforced polypropylene

NASA Astrophysics Data System (ADS)

Scantamburlo, Andrea; Gazzola, Luca; Sorgato, Marco; Lucchetta, Giovanni

2018-05-01

In parts manufactured by injection molding of long glass fiber reinforced polypropylene, the local fiber orientation, fiber concentration and fiber length distribution varies along both the thickness direction and the flow path. This heterogeneous microstructure significantly influences the mechanical properties variability in the molded parts. The aim of this work is to investigate the influence of the matrix viscosity, the injection speed and the mold geometry on the fiber concentration distribution. In particular, the factors involved in fiber-matrix separation and fiber pull-out during the injection phases were analyzed in order to understand the phenomenon.

Study on the repeatability of manufacturing nano-silica (SiO2) reinforced composite laminates

NASA Astrophysics Data System (ADS)

Prince Jeya Lal, L.; Ramesh, S.; Natarajan, Elango

2018-04-01

Repeatability to manufacture nano-silica reinforced composite laminates with consistent mechanical properties is studied. In this study, composite laminates are manufactured by hand layup and there after mechanical properties of the laminates are evaluated under tensile and flexural loading conditions. Composite laminates are fabricated and tested under equivalent conditions. Plain weave E-Glass fabric and epoxy LY556 are used as reinforcement and matrix. Nano-silica of size 17nm is used as filler. To enhance the reliability of composite characterization, utmost care is taken to avoid defects like voids, surface defects and under-saturations. Homogeneous distribution of nano silica in matrix is analyzed using TEM study. Inconsistencies in mechanical properties are quantified by coefficient of variation. In this study, the coefficient of variation is estimated in terms of break load for tensile test is 4.45 and for flexural test is 2.27 and is well within the limits.

Micro-structure and Mechanical Properties of Nano-TiC Reinforced Inconel 625 Deposited using LAAM

NASA Astrophysics Data System (ADS)

Bi, G.; Sun, C. N.; Nai, M. L.; Wei, J.

In this paper, deposition of Ni-base Inconel 625 mixed with nano-TiC powders using laser aided additive manufacturing (LAAM) was studied. Micro-structure and mechanical properties were intensively investigated. The results showed that nano-size TiC distributed uniformly throughout the Ni- matrix. Inconel 625 can be reinforced by the strengthened grain boundaries with nano-size TiC. Improved micro-hardness and tensile properties were observed.

Laser absorption of carbon fiber reinforced polymer with randomly distributed carbon fibers

NASA Astrophysics Data System (ADS)

Hu, Jun; Xu, Hebing; Li, Chao

2018-03-01

Laser processing of carbon fiber reinforced polymer (CFRP) is a non-traditional machining method which has many prospective applications. The laser absorption characteristics of CFRP are analyzed in this paper. A ray tracing model describing the interaction of the laser spot with CFRP is established. The material model contains randomly distributed carbon fibers which are generated using an improved carbon fiber placement method. It was found that CFRP has good laser absorption due to multiple reflections of the light rays in the material’s microstructure. The randomly distributed carbon fibers make the absorptivity of the light rays change randomly in the laser spot. Meanwhile, the average absorptivity fluctuation is obvious during movement of the laser. The experimental measurements agree well with the values predicted by the ray tracing model.

Polypropylene fiber reinforced concrete detention ponds : final report.

DOT National Transportation Integrated Search

1995-09-01

In 1991, two Durafiber polypropylene fiber reinforced concrete lined detention ponds were constructed. The detention ponds are located on the north side of the 181st Avenue Interchange, on the Columbia River Highway (I-84), approximately ten miles ea...

Thermo-oxidative stability studies of PMR-15 polymer matrix composites reinforced with various fibers

NASA Technical Reports Server (NTRS)

Bowles, Kenneth J.

1990-01-01

An experimental study was conducted to measure the thermo-oxidative stability of PMR-15 polymer matrix composites reinforced with various fibers and to observe differences in the way they degrade in air. The fibers that were studied included graphite and the thermally stable Nicalon and Nextel ceramic fibers. Weight loss rates for the different composites were assessed as a function of mechanical properties, specimen geometry, fiber sizing, and interfacial bond strength. Differences were observed in rates of weight loss, matrix cracking, geometry dependency, and fiber-sizing effects. It was shown that Celion 6000 fiber-reinforced composites do not exhibit a straight-line Arrhenius relationship at temperatures above 316 C.

The formation of web-like connection among electrospun chitosan/PVA fiber network by the reinforcement of ellipsoidal calcium carbonate.

PubMed

Sambudi, Nonni Soraya; Kim, Minjeong G; Park, Seung Bin

2016-03-01

The electrospun fibers consist of backbone fibers and nano-branch network are synthesized by loading of ellipsoidal calcium carbonate in the mixture of chitosan/poly(vinyl alcohol) (PVA) followed by electrospinning. The synthesized ellipsoidal calcium carbonate is in submicron size (730.7±152.4 nm for long axis and 212.6±51.3 nm for short axis). The electrospun backbone fibers experience an increasing in diameter by loading of calcium carbonate from 71.5±23.4 nm to 281.9±51.2 nm. The diameters of branch fibers in the web-network range from 15 nm to 65 nm with most distributions of fibers are in 30-35 nm. Calcium carbonate acts as reinforcing agent to improve the mechanical properties of fibers. The optimum value of Young's modulus is found at the incorporation of 3 wt.% of calcium carbonate in chitosan/PVA fibers, which is enhanced from 15.7±3 MPa to 432.4±94.3 MPa. On the other hand, the ultimate stress of fibers experiences a decrease. This result shows that the fiber network undergoes changes from flexible to more stiff by the inclusion of calcium carbonate. The thermal analysis results show that the crystallinity of polymer is changed by the existence of calcium carbonate in the fiber network. The immersion of fibers in simulated body fluid (SBF) results in the formation of apatite on the surface of fibers. Copyright © 2015 Elsevier B.V. All rights reserved.

Experimental investigation of steel fiber-reinforced concrete beams under cyclic loading

NASA Astrophysics Data System (ADS)

Ranjbaran, Fariman; Rezayfar, Omid; Mirzababai, Rahmatollah

2018-03-01

An experimental study has been conducted to study the cyclic behavior of reinforced concrete beams in which steel fibers were added to the concrete mix. Seven similar geometrically specimens in full scale were studied under four- point bending test in the form of slow cyclic loading. One sample as a control specimen was made without steel fibers or 0% volume fraction (vf) and six other samples with 1, 2 and 4% vf of steel fibers in twin models. The maximum and ultimate resistance, ductility, degradation of loading and unloading stiffness, absorption and dissipation of energy and equivalent viscous damping were studied in this investigation and the effect of steel fibers on the cyclic behavior was compared with each other. Generally, the addition of steel fibers up to a certain limit value (vf = 2%) improves the cyclic behavior of reinforced concrete beams and results in the increase of maximum strength and ultimate displacement.

Strength and deformability of compressed concrete elements with various types of non-metallic fiber and rods reinforcement under static loading

NASA Astrophysics Data System (ADS)

Nevskii, A. V.; Baldin, I. V.; Kudyakov, K. L.

2015-01-01

Adoption of modern building materials based on non-metallic fibers and their application in concrete structures represent one of the important issues in construction industry. This paper presents results of investigation of several types of raw materials selected: basalt fiber, carbon fiber and composite fiber rods based on glass and carbon. Preliminary testing has shown the possibility of raw materials to be effectively used in compressed concrete elements. Experimental program to define strength and deformability of compressed concrete elements with non-metallic fiber reinforcement and rod composite reinforcement included design, manufacture and testing of several types of concrete samples with different types of fiber and longitudinal rod reinforcement. The samples were tested under compressive static load. The results demonstrated that fiber reinforcement of concrete allows increasing carrying capacity of compressed concrete elements and reducing their deformability. Using composite longitudinal reinforcement instead of steel longitudinal reinforcement in compressed concrete elements insignificantly influences bearing capacity. Combined use of composite rod reinforcement and fiber reinforcement in compressed concrete elements enables to achieve maximum strength and minimum deformability.

Tribological dry sliding behavior of chopped carbon fiber reinforced polyetheretherketone

NASA Astrophysics Data System (ADS)

Chumaevskii, A. V.; Ivanov, A. N.; Filippov, A. V.; Rubtsov, V. E.; Kolubaev, E. A.

2017-12-01

Tribological tests on 3D printed pure polyetheretherketone and carbon fiber reinforced polyetheretherketone samples were carried out. The negative effect of carbon fiber sticking out of the matrix on wear and sliding process stability was revealed. These fibers may be too long and oriented to the worn surface in a manner that prevents their removal by wear so that the worn surface becomes irregular and the sliding process instable.

Effect of fiber orientation on the failure behavior of a glass-fiber reinforced thermoplastic composite

NASA Astrophysics Data System (ADS)

Liang, Jiaai; Kalyanasundaram, Shankar

2017-05-01

In this study, hour-glass specimens made of a glass-fiber reinforced polypropylene composite with different fiber orientations were stamp formed in an open die. Strains on the surfaces of these specimens were recorded by a 3D photogrammetric measurement system. Specimens were cut into the designed shapes with two different fiber orientations [0°/90° and 45°/45°]. Based on the forming limit diagrams drawn for these material systems, it is found that change in fiber orientation induces change in deformation mode and different forming limit in strains.

Large-scale and highly efficient synthesis of micro- and nano-fibers with controlled fiber morphology by centrifugal jet spinning for tissue regeneration

NASA Astrophysics Data System (ADS)

Ren, Liyun; Pandit, Vaibhav; Elkin, Joshua; Denman, Tyler; Cooper, James A.; Kotha, Shiva P.

2013-02-01

PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a highly efficient synthesis method for micron- to nano-sized fibers with a production rate up to 0.5 g min-1. During the centrifugal jet spinning process, a polymer solution jet is stretched by the centrifugal force of a rotating chamber. By engineering the rheological properties of the polymer solution, solvent evaporation rate and centrifugal force that are applied on the solution jet, polyvinylpyrrolidone (PVP) and poly(l-lactic acid) (PLLA) composite fibers with various diameters are fabricated. Viscosity measurements of polymer solutions allowed us to determine critical polymer chain entanglement limits that allow the generation of continuous fiber as opposed to beads or beaded fibers. Above a critical concentration at which polymer chains are partially or fully entangled, lower polymer concentrations and higher centrifugal forces resulted in thinner fibers. Etching of PVP from the PLLA-PVP composite fibers doped with increasing PVP concentrations yielded PLLA fibers with increasing nano-scale surface roughness and porosity, which increased the fiber hydrophilicity dramatically. Scanning electron micrographs of the etched composite fibers suggest that PVP and PLLA were co-contiguously phase separated within the composite fibers during spinning and nano-scale roughness features were created after the partial etching of PVP. To study the tissue regeneration efficacy of the engineered PLLA fiber matrix, human dermal fibroblasts are used to simulate partial skin graft. Fibers with increased PLLA surface roughness and porosity demonstrated a trend towards higher cell attachment and proliferation.PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a

Effect of fiber reinforcements on thermo-oxidative stability and mechanical properties of polymer matrix composites

NASA Technical Reports Server (NTRS)

Bowles, Kenneth J.

1991-01-01

A number of studies have investigated the thermo-oxidative behavior of polymer matrix composites. Two significant observations have been made from these research efforts: (1) fiber reinforcement has a significant effect on composite thermal stability; and (2) geometric effects must be considered when evaluating thermal aging data. A compilation of some results from these studies is presented, and this information shows the influence of the reinforcement fibers on the oxidative degradation of various polymer matrix composites. The polyimide PMR-15 was the matrix material that was used in these studies. The control composite material was reinforced with Celion 6000 graphite fiber. T-40R graphite fibers, along with some very stable ceramic fibers were selected as reinforcing fibers because of their high thermal stability. The ceramic fibers were Nicalon (silicon carbide) and Nextel 312 (alumina-silica-boron oxide). The mechanical properties of the two graphite fiber composites were significantly different, probably owing to variations in interfacial bonding between the fibers and the polyimide matrix. The Celion 6000/PMR-15 bond is very tight but the T-40/PMR-15 bond is less tight. Three oxidation mechanisms were observed: (1) the preferential oxidation of the Celion 6000 fiber ends at cut surfaces, leaving a surface of matrix material with holes where the fiber ends were originally situated; (2) preferential oxidation of the composite matrix; and (3) interfacial degradation by oxidation. The latter two mechanisms were also observed on fiber end cut surfaces. The fiber and interface attacks appeared to initiate interfiber cracking along these surfaces.

Basalt fiber reinforced porous aggregates-geopolymer based cellular material

NASA Astrophysics Data System (ADS)

Luo, Xin; Xu, Jin-Yu; Li, Weimin

2015-09-01

Basalt fiber reinforced porous aggregates-geopolymer based cellular material (BFRPGCM) was prepared. The stress-strain curve has been worked out. The ideal energy-absorbing efficiency has been analyzed and the application prospect has been explored. The results show the following: fiber reinforced cellular material has successively sized pore structures; the stress-strain curve has two stages: elastic stage and yielding plateau stage; the greatest value of the ideal energy-absorbing efficiency of BFRPGCM is 89.11%, which suggests BFRPGCM has excellent energy-absorbing property. Thus, it can be seen that BFRPGCM is easy and simple to make, has high plasticity, low density and excellent energy-absorbing features. So, BFRPGCM is a promising energy-absorbing material used especially in civil defense engineering.

Deformation behavior of FRP-metal composites locally reinforced with carbon fibers

NASA Astrophysics Data System (ADS)

Scholze, M.; Kolonko, A.; Lindner, T.; Lampke, T.; Helbig, F.

2016-03-01

This study investigates variations of hybrid laminates, consisting of one aluminum sheet and a unidirectional glass fiber (GF) reinforced polyamide 6 (PA6) basic structure with partial carbon fiber (CF) reinforcement. To create these heterogeneous FRP laminates, it is necessary to design and produce semi-finished textile-based products. Moreover, a warp knitting machine in conjunction with a warp thread offset unit was used to generate bionic inspired compounds. By the variation of stacking prior to the consolidation process of the hybrid laminate, an oriented CF reinforcement at the top and middle layer of the FRP is realized. In both cases the GFRP layer prevents contact between the aluminum and carbon fibers. In so doing, the high strength of carbon fibers can be transferred to the hybrid laminate in load directions with an active prevention of contact corrosion. The interface strength between thermoplastic and metal component was improved by a thermal spray coating on the aluminum sheet. Because of the high surface roughness and porosity, mechanical interlock was used to provide high interface strength without bonding agents between both components. The resulting mechanical properties of the hybrid laminates are evaluated by three point bending tests in different load directions. The effect of local fiber orientation and layer positioning on failure and deformation mechanism is additionally investigated by digital image correlation (DIC).

Environmental durability of reinforced concrete deck girders strengthened for shear with surface-bonded carbon fiber-reinforced polymer : final report.

DOT National Transportation Integrated Search

2009-05-01

This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort ...

Environmental durability of reinforced concrete deck girders strengthened for shear with surface bonded carbon fiber-reinforced polymer : final report.

DOT National Transportation Integrated Search

2009-05-01

This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced : concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effor...

Corrosion and tribological properties of basalt fiber reinforced composite materials

NASA Astrophysics Data System (ADS)

Ha, Jin Cheol; Kim, Yun-Hae; Lee, Myeong-Hoon; Moon, Kyung-Man; Park, Se-Ho

2015-03-01

This experiment has examined the corrosion and tribological properties of basalt fiber reinforced composite materials. There were slight changes of weight after the occurring of corrosion based on time and H2SO4 concentration, but in general, the weight increased. It is assumed that this happens due to the basalt fiber precipitate. Prior to the corrosion, friction-wear behavior showed irregular patterns compared to metallic materials, and when it was compared with the behavior after the corrosion, the coefficient of friction was 2 to 3 times greater. The coefficient of friction of all test specimen ranged from 0.1 to 0.2. Such a result has proven that the basalt fiber, similar to the resin rubber, shows regular patterns regardless of time and H2SO4 concentration because of the space made between resins and reinforced materials.

Reinforcing and Toughening Effects of Bamboo Pulp Fiber on Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Fiber Composites.

USDA-ARS?s Scientific Manuscript database

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/bamboo pulp fiber composites were melt-compounded and injection-molded. Tensile, impact and dynamic mechanical properties of the composites were studied. In contrast to many other short natural fiber reinforced biocomposites which demonstrate decre...

Fracture behavior of glass fiber reinforced polymer composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avci, A.; Arikan, H.; Akdemir, A

2004-03-01

Chopped strand glass fiber reinforced particle-filled polymer composite beams with varying notch-to-depth ratios and different volume fractions of glass fibers were investigated in Mode I fracture using three-point bending tests. Effects of polyester resin content and glass fiber content on fracture behavior was also studied. Polyester resin contents were used 13.00%%, 14.75%, 16.50%, 18.00% and 19.50%, and glass fiber contents were 1% and 1.5% of the total weight of the polymer composite system. Flexural strength of the polymer composite increases with increase in polyester and fiber content. The critical stress intensity factor was determined by using several methods such asmore » initial notch depth method, compliance method and J-integral method. The values of K{sub IC} obtained from these methods were compared.« less

Evaluation of elastic modulus and hardness of crop stalks cell walls by nano-indentation

Treesearch

Yan Wu; Siqun Wang; Dingguo Zhou; Cheng Xing; Yang Zhang; Zhiyong Cai

2010-01-01

Agricultural biomaterials such as crop stalks are natural sources of cellulosic fiber and have great potential as reinforced materials in bio-composites. In order to evaluate their potential as materials for reinforcement, the nano-mechanical properties of crop-stalk cell walls, i.e. those of cotton (Gossypium herbaceu) stalk, soybean (Glycine max) stalk, cassava (...

Bridge toughening in fiber-reinforced composites: A three-dimensional discrete fiber model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, K.X.; Huang, Y.; Chandra, A.

1995-07-01

The fracture behavior of unidirectionally fiber-reinforced composites is the principal focus of this paper. The model proposed here is three-dimensional and accounts for the effects of local fiber-crack interactions on spatial variations of crack tip behavior. The model also consistently accounts for the effect of composite anisotropy by embedding a penny-shaped crack in an orthotropic composite medium. Three factors are identified that influence the reductions of stress intensity factors (SIFS) due to fiber bridging: a dimensionless configuration constant, a fiber distribution pattern, and a fiber volume fraction. The model reveals that the fiber distribution pattern does not alter the spatialmore » mean of the SIFS, although it does affect the oscillational amplitude. The dimensionless configuration constant determines the extent of the bridging effect and provides guidance regarding possible avenues for enhancing bridge toughening. The design curve of SIFs (retarded by fiber bridging) vs the fiber volume fraction shows that the isotropic and orthotropic solutions differ just slightly from each other. However, the energy release rate obtained by an isotropic analysis (widely claimed to be the equivalent of SIFs in bridging models) could, significantly underestimate the bridging effect.« less

Physico-chemical studies of hardened cement paste structure with micro-reinforcing fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steshenko, Aleksei, E-mail: steshenko.alexey@gmail.com; Kudyakov, Aleksander; Konusheva, Viktoriya

The results of physico-chemical studies of modified hardened cement paste with micro-reinforcing fibers are given in this article. The goal was to study the reasons of the increase of strength properties of modified hardened cement paste by the method of X-ray diffraction and electron microscopy. It is shown that the use of mineral fibers in the production of cement based material has positive effect on its properties. The study found out that the increase in the strength of the hardened cement paste with micro-reinforcing fibers is due to the increase of the rate of hydration of cement without a significantmore » change in the phase composition in comparison with hardened cement paste without additive. The results of microstructure investigation (of control samples and samples of the reinforced hardened cement paste) have shown that introduction of mineral fibers in the amount of 0.1-2 % by weight of cement provides the structure of the homogeneous microporous material with uniform distribution of the crystalline phase provided by densely packed hydrates.« less

Elastic properties of rigid fiber-reinforced composites

NASA Astrophysics Data System (ADS)

Chen, J.; Thorpe, M. F.; Davis, L. C.

1995-05-01

We study the elastic properties of rigid fiber-reinforced composites with perfect bonding between fibers and matrix, and also with sliding boundary conditions. In the dilute region, there exists an exact analytical solution. Around the rigidity threshold we find the elastic moduli and Poisson's ratio by decomposing the deformation into a compression mode and a rotation mode. For perfect bonding, both modes are important, whereas only the compression mode is operative for sliding boundary conditions. We employ the digital-image-based method and a finite element analysis to perform computer simulations which confirm our analytical predictions.

Mechanics of Elevated Temperature Fatigue Damage in Fiber-Reinforced Ceramics

DTIC Science & Technology

1993-01-01

Wang and Parvizi- Majidi 117] have measured the frictional shear stress in Nicalon"h(CAS-lI composites; shear stress ranged from 12.4±2.6 for fiber...Parvizi- Majidi . "Mechanical Behavior of NicaloniM Fiber-Reinforced Calcium-Aluminosilicate Matrix Composites," Ceram. Eng. Sci. Proc., 11 [9-101 1607

The effect of fiber treatment on abrasive wear properties of palm fiber reinforced epoxy composite

NASA Astrophysics Data System (ADS)

Razak, Muhammad Firdaus Abdul; Bakar, Mimi Azlina Abu; Kasolang, Salmiah; Ahmad, Mohamad Ali

2017-12-01

Oil palm industries generate at least 30 million tons of lignocellulosic biomass annually in the form of oil palm trunks (OPT), empty fruit bunches (EFB), oil palm fronds (OPF) and palm pressed fibres (PPF). The palm fiber is one of the natural fibers used as reinforcement in composite materials in order to decrease environmental issues and promotes utilization of renewable resources. This paper presents a study on the effect of alkaline treatment on wear properties of palm fiber reinforced epoxy resin composite. Abrasive wear testing was deployed to investigate the wear profile of the composite surfaces. Testing was carried out which focused on the effect of alkaline treatment to the palm fiber under different amounts of fiber loading i.e. 1 wt%, 3 wt%, 5 wt% and 7 wt%. The palm fibers were soaked into 6 % of alkaline solution or natrium hydroxide (NaOH) for 12 hours. The fiber was treated in order to remove amorphous materials such as hemicelluloses, lignins and pectins of the fiber. The wear test samples were fabricated using hand lay-up technique and cured at room temperature for 24 hours. Surface roughness of the composite material was also measured using the surface measuring instrument. Dry sliding wear test was performed at room temperature at a constant velocity of 1.4 m/s with a constant load of 10 N by using the Abrasion Test Machine. Result shows that 5 wt% and 7 wt% treated palm fiber loadings have better specific wear rate compared to lower fiber loadings. The finding of this study contributes towards material development and utilization in promoting `waste into wealth' which is in line with national aspiration.

Understanding the interfacial chain dynamics of fiber-reinforced polymer composite

NASA Astrophysics Data System (ADS)

Goswami, Monojoy; Carrillo, Jan-Michael; Naskar, Amit; Sumpter, Bobby

The polymer-fiber interface plays a major role in determining the structural and dynamical properties of fiber reinforced composite materials. We utilized LAMMPS MD package to understand the interfacial properties at the nanoscale. Coarse-grained flexible polymer chains are introduced to compare the various structures and dynamics of the polymer chains. Our preliminary simulation study shows that the rigidity of the polymer chain affects the interfacial morphology and dynamics of the chain on a flat surface. In this work, we identified the `immobile inter-phase' morphology and relate it to rheological properties. We calculated the viscoelastic properties, e.g., shear modulus and storage modulus, which are compared with experiments. MD simulations are used to show the variation of viscoelastic properties with polymer volume fraction. The nanoscale segmental and chain relaxation are calculated from the MD simulations and compared to the experimental data. These observations will be able to identify the fundamental physics behind the effect of the polymer-fiber interactions and orientation of the fiber to the overall rheological properties of the fiber reinforced polymer matrix. Funding for the project was provided by ORNLs Laboratory Directed Research and Development (LDRD) program.

Investigation of mechanical properties of kenaf, hemp and E-glass fiber reinforced composites

NASA Astrophysics Data System (ADS)

Dinesh, Veena; Shivanand, H. K.; Vidyasagar, H. N.; Chari, V. Srinivasa

2018-04-01

Recently the use of fiber reinforced polymer composite in the automobile, aerospace overwhelming designing sectors has increased tremendously due to the ecological issues and health hazard possessed by the synthetic fiber during disposal and manufacturing. The paper presents tensile strength, flexural strength and hardness of kenaf-E glass-kenaf, hemp-E glass-hemp and kenaf-E glass-hemp fiber reinforced polyester composites. The composite plates are shaped according to the standard geometry and uni-axially loaded in order to investigate the tensile responses of each combination. In addition to the physical and mechanical properties, processing methods and application of kenaf and hemp fiber composites is also discussed.

Glass Fiber Reinforced Polypropylene Mechanical Properties Enhancement by Adhesion Improvement

PubMed Central

Etcheverry, Mariana; Barbosa, Silvia E.

2012-01-01

Glass fibers (GF) are the reinforcement agent most used in polypropylene (PP) based composites, as they have good balance between properties and costs. However, their final properties are mainly determined by the strength and stability of the polymer-fiber interphase. Fibers do not act as an effective reinforcing material when the adhesion is weak. Also, the adhesion between phases can be easily degraded in aggressive environmental conditions such as high temperatures and/or elevated moisture, and by the stress fields to which the material may be exposed. Many efforts have been done to improve polymer-glass fiber adhesion by compatibility enhancement. The most used techniques include modifications in glass surface, polymer matrix and/or both. However, the results obtained do not show a good costs/properties improvement relationship. The aim of this work is to perform an accurate analysis regarding methods for GF/PP adhesion improvement and to propose a new route based on PP in-situ polymerization onto fibers. This route involves the modification of fibers with an aluminum alkyl and hydroxy-α-olefin and from there to enable the growth of the PP chains using direct metallocenic copolymerization. The adhesion improvements were further proved by fragmentation test, as well as by mechanical properties measurements. The strength and toughness increases three times and the interfacial strength duplicates in PP/GF composites prepared with in-situ polymerized fibers. PMID:28817025

Dynamic Loading and Characterization of Fiber-Reinforced Composites

NASA Astrophysics Data System (ADS)

Sierakowski, Robert L.; Chaturvedi, Shive K.

1997-02-01

Emphasizing polymer based fiber-reinforced composites, this book is designed to provide readers with a significant understanding of the complexities involved in characterizing dynamic events and the corresponding response of advanced fiber composite materials and structures. These elements include dynamic loading devices, material properties characterization, analytical and experimental techniques to assess the damage and failure modes associated with various dynamic loading events. Concluding remarks are presented throughout the text which summarize key points and raise issues related to important research needed.

Evaluation of tensile strength of hybrid fiber (jute/gongura) reinforced hybrid polymer matrix composites

NASA Astrophysics Data System (ADS)

Venkatachalam, G.; Gautham Shankar, A.; Vijay, Kumar V.; Chandan, Byral R.; Prabaharan, G. P.; Raghav, Dasarath

2015-07-01

The polymer matrix composites attract many industrial applications due to its light weight, less cost and easy for manufacturing. In this paper, an attempt is made to prepare and study of the tensile strength of hybrid (two natural) fibers reinforced hybrid (Natural + Synthetic) polymer matrix composites. The samples were prepared with hybrid reinforcement consists of two different fibers such as jute and Gongura and hybrid polymer consists of polyester and cashew nut shell resins. The hybrid composites tensile strength is evaluated to study the influence of various fiber parameters on mechanical strength. The parameters considered here are the duration of fiber treatment, the concentration of alkali in fiber treatment and nature of fiber content in the composites.

Evaluation of RC Bridge Piers Retrofitted using Fiber-Reinforced Polymer (FRP)

NASA Astrophysics Data System (ADS)

Shayanfar, M. A.; Zarrabian, M. S.

2008-07-01

For many long years, steel reinforcements have been considered as the only tool for concrete confinements and studied widely, but nowadays application of Fiber Reinforced Polymer (FRP) as an effective alternative is well appreciated. Many bridges have been constructed in the past that are necessary to be retrofitted for resisting against the earthquake motions. The objective of this research is evaluation of nonlinear behavior of RC bridge piers. Eight RC bridge piers have been modeled by ABAQUS software under micromechanical model for homogeneous anisotropic fibers. Also the Bilinear Confinement Model by Nonlinear Transition Zone of Mirmiran has been considered. Then types and angles of fibers and their effects on the final responses were evaluated [1]. Finally, effects of retrofitting are evaluated and some suggestions presented.

Exploratory investigation of high-performance fiber-reinforced cementitious composites for crack control.

DOT National Transportation Integrated Search

2008-01-01

This study evaluated high-performance fiber-reinforced cementitious composites (HPFRCC), which are mortar mixtures with synthetic and steel fibers. The feasibility of using HPFRCC technology for transportation applications by the Virginia Department ...

Fiber-Reinforced Origamic Robotic Actuator.

PubMed

Yi, Juan; Chen, Xiaojiao; Song, Chaoyang; Wang, Zheng

2018-02-01

A novel pneumatic soft linear actuator Fiber-reinforced Origamic Robotic Actuator (FORA) is proposed with significant improvements on the popular McKibben-type actuators, offering nearly doubled motion range, substantially improved force profile, and significantly lower actuation pressure. The desirable feature set is made possible by a novel soft origamic chamber that expands radially while contracts axially when pressurized. Combining this new origamic chamber with a reinforcing fiber mesh, FORA generates very high traction force (over 150N) and very large contractile motion (over 50%) at very low input pressure (100 kPa). We developed quasi-static analytical models both to characterize the motion and forces and as guidelines for actuator design. Fabrication of FORA mostly involves consumer-grade three-dimensional (3D) printing. We provide a detailed list of materials and dimensions. Fabricated FORAs were tested on a dedicated platform against commercially available pneumatic artificial muscles from Shadow and Festo to showcase its superior performances and validate the analytical models with very good agreements. Finally, a robotic joint was developed driven by two antagonistic FORAs, to showcase the benefits of the performance improvements. With its simple structure, fully characterized mechanism, easy fabrication procedure, and highly desirable performance, FORA could be easily customized to application requirements and fabricated by anyone with access to a 3D printer. This will pave the way to the wider adaptation and application of soft robotic systems.

Effects of Fiber Coating Composition on Mechanical Behavior of Silicon Carbide Fiber-Reinforced Celsian Composites

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Elderidge, Jeffrey I.

1998-01-01

Celsian matrix composites reinforced with Hi-Nicalon fibers, precoated with a dual layer of BN/SiC by chemical vapor deposition in two separate batches, were fabricated. Mechanical properties of the composites were measured in three-point flexure. Despite supposedly identical processing, the composite panels fabricated with fibers coated in two batches exhibited substantially different mechanical behavior. The first matrix cracking stresses (sigma(sub mc)) of the composites reinforced with fibers coated in batch 1 and batch 2 were 436 and 122 MPa, respectively. This large difference in sigma(sub mc) was attributed to differences in fiber sliding stresses(tau(sub friction)), 121.2+/-48.7 and 10.4+/-3.1 MPa, respectively, for the two composites as determined by the fiber push-in method. Such a large difference in values of tau(sub friction) for the two composites was found to be due to the difference in the compositions of the interface coatings. Scanning Auger microprobe analysis revealed the presence of carbon layers between the fiber and BN, and also between the BN and SiC coatings in the composite showing lower tau(sub friction). This resulted in lower sigma(sub mc) in agreement with the ACK theory. The ultimate strengths of the two composites, 904 and 759 MPa, depended mainly on the fiber volume fraction and were not significantly effected by tau(sub friction) values, as expected. The poor reproducibility of the fiber coating composition between the two batches was judged to be the primary source of the large differences in performance of the two composites.

Comparative properties of cellulose nano-crystals from native and mercerized cotton fibers

USDA-ARS?s Scientific Manuscript database

Stable aqueous suspensions of cellulose nano-crystals (CNCs) were fabricated from both native and mercerized cotton fibers by sulfuric acid hydrolysis, followed by high-pressure homogenization. Fourier Transform Infrared Spectrometry and Wide-angle X-Ray Diffraction data showed that the fibers had b...

Effect of fiber reinforcement on thermo-oxidative stability and mechanical properties of polymer matrix composites

NASA Technical Reports Server (NTRS)

Bowles, K. J.

1992-01-01

A number of studies have investigated the thermooxidative behavior of polymer matrix composites. Two significant observations have been made from these research efforts: (1) fiber reinforcement has a significant effect on composite thermal stability; and (2) geometric effects must be considered when evaluating thermal aging data. The polyimide PMR-15 was the matrix material used in these studies. The control composite material was reinforced with Celion 6000 graphite fiber. T-4OR graphite fibers, along with some very stable ceramic fibers were selected as reinforcing fibers because of their high thermal stability. The ceramic fibers were Nicalon (silicon carbide) and Nextel 312 (alumina-silica-boron oxide). The mechanical properties of the two graphite fiber composites were significantly different, probably owing to variations in interfacial bonding between the fibers and the polyimide matrix. Three oxidation mechanisms were observed: (1) the preferential oxidation of the Celion 6000 fiber ends at cut surfaces, leaving a surface of matrix material with holes where the fiber ends were originally situated; (2) preferential oxidation of the composite matrix; and (3) interfacial degradation by oxidation. The latter two mechanisms were also observed on fiber end cut surfaces. The fiber and interface attacks appeared to initiate interfiber cracking along these surfaces.

Cracking and debonding of a thin fiber reinforced concrete overlay : research brief.

DOT National Transportation Integrated Search

2017-03-01

Experimental tests found that the tensile interfacial energy : increased with fiber-reinforcement. Also bond tests indicated : that interfacial fracture occurred through the overlay mixture and : was proportional to the number of fibers which interse...

Fiber-reinforced materials: finite elements for the treatment of the inextensibility constraint

NASA Astrophysics Data System (ADS)

Auricchio, Ferdinando; Scalet, Giulia; Wriggers, Peter

2017-12-01

The present paper proposes a numerical framework for the analysis of problems involving fiber-reinforced anisotropic materials. Specifically, isotropic linear elastic solids, reinforced by a single family of inextensible fibers, are considered. The kinematic constraint equation of inextensibility in the fiber direction leads to the presence of an undetermined fiber stress in the constitutive equations. To avoid locking-phenomena in the numerical solution due to the presence of the constraint, mixed finite elements based on the Lagrange multiplier, perturbed Lagrangian, and penalty method are proposed. Several boundary-value problems under plane strain conditions are solved and numerical results are compared to analytical solutions, whenever the derivation is possible. The performed simulations allow to assess the performance of the proposed finite elements and to discuss several features of the developed formulations concerning the effective approximation for the displacement and fiber stress fields, mesh convergence, and sensitivity to penalty parameters.

The Effect of Moisture on the Properties of an Aramid/Epoxy Composite

DTIC Science & Technology

1983-05-01

COMPOSITES DEVELOP~ENT DIVISiON...TYPE OF REPORT II PERIOD COV ERED THE EFFECT OF MOISTURE ON THE PROPERTIES OF AN Final Report ARAMID/EPOXY COMPOSITE ’· PERFORMING ORG. REPORT...ConrJnue on reror•ralt •rde ff n~(•.’lsar:,.- .,d ldenrl(y b~ L/odc numbe-r) Composite Materials Fatigue (mechanic s ) Aramid/epoxy composites

Coir fiber reinforced polypropylene composite panel for automotive interior applications

Treesearch

Nadir Ayrilmis; Songklod Jarusombuti; Vallayuth Fueangvivat; Piyawade Bauchongkol; Robert H. White

2011-01-01

In this study, physical, mechanical, and flammability properties of coconut fiber reinforced polypropylene (PP) composite panels were evaluated. Four levels of the coir fiber content (40, 50, 60, and 70 % based on the composition by weight) were mixed with the PP powder and a coupling agent, 3 wt % maleic anhydride grafted PP (MAPP) powder. The water resistance and the...

Nondestructive Evaluation of Advanced Fiber Reinforced Polymer Matrix Composites: A Technology Assessment

NASA Technical Reports Server (NTRS)

Yolken, H. Thomas; Matzkanin, George A.

2009-01-01

Because of their increasing utilization in structural applications, the nondestructive evaluation (NDE) of advanced fiber reinforced polymer composites continues to receive considerable research and development attention. Due to the heterogeneous nature of composites, the form of defects is often very different from a metal and fracture mechanisms are more complex. The purpose of this report is to provide an overview and technology assessment of the current state-of-the-art with respect to NDE of advanced fiber reinforced polymer composites.

Characterization of Thermal Behavior of Epoxy Composites Reinforced with Curaua Fibers by Differential Scanning Calorimetry

NASA Astrophysics Data System (ADS)

Barcelos, Mariana A.; Ribeiro, Carolina Gomes D.; Ferreira, Jordana; Vieira, Janaina da S.; Margem, Frederico M.; Monteiro, Sergio N.

Epoxy composites reinforced with natural lignocellulosic fibers have, in recent times, been gaining attention in engineering areas as lighter and cheaper alternatives for traditional composites such as the "fiberglass". The curaua fiber is the one strongest today being considered as reinforcement of composites for automobile interior parts. In fact, several studies are currently being dedicated to curaua fiber composites since physical and mechanical properties are required for practical uses. In this work, the thermal behavior of epoxy composites reinforced with up to 30 % in volume of curaua fibers was investigated by differential scanning calorimetry, DSC. The results showed endothermic and exothermic events associated with water release and possible molecular chain amorphous transformation. Comparison with similar composites permitted to propose mechanism that explains this DSC thermal behavior.

Development and testing of fiber-reinforced composite space maintainers.

PubMed

Kulkarni, Gajanan; Lau, Domenic; Hafezi, Sara

2009-01-01

The purpose of this study was to develop a clinically acceptable, cheaper, and more expedient alternative to standard stainless steel band and loop space maintainers. Loops of fiber-reinforced composites were constructed using polyethylene fiber (Ribbond) and glass fiber (Sticktech). The loops were bonded on extracted third molars and tested for flexural strength before and after thermocycling and following repair of the appliances after initial stress failure. Bacterial colonization on the appliances was also compared. Conventional stainless steel band and loop space maintainers cemented with Ketac were controls. Ribbond samples demonstrated higher flexural strength than Sticktech and the control (P<.05). No differences were noted among the other samples and the control. The repaired Ribbond samples were statistically comparable in flexural strength to the initial samples. Thermocycling resulted in decreased flexural strength of both Ribbond and Sticktech (P<.05). Thermocycled Ribbond samples were comparable to the control, but a lower flexural strength was noted for Sticktech samples (P<.05). While all space maintainers allowed some bacterial adhesion, Sticktech showed higher Streptococcus mutans counts than Ribbond (P=.06). Ribbond space-maintainers are comparable to the stainless steel in terms of physical strength and biofilm formation. The fiber-reinforced composite space maintainers may be a clinically acceptable and expedient alternative to the conventional band-loop appliance.

[A maxillary premolar reconstruction with a glass fiber reinforced post].

PubMed

Viţalariu, Anca Mihaela; Antohe, Magda; Bahrim, Delia; Tatarciuc, Monica

2006-01-01

This paper presents the case of a 37 years old female patient who needed a reconstruction of an endodontic treated' second maxillary premolar. The patient presented large areas of occlusal abrasion caused by bruxism, therefore the solution consisted of a reconstruction with a non-metallic post reinforced with glass fibers. In such cases, the excessive occlusal forces developed by bruxism can produce a radicular fracture if the tooth would be reconstructed with a rigid metallic post. The glass-fiber reinforced post has some important qualities, which render it more suitable in most clinical cases: it is easy to use; has the ability to bond with restorative resins; decreases the risk of tooth fracture and provides better esthetics.

Dynamic fracture toughness of cellulose-fiber-reinforced polypropylene : preliminary investigation of microstructural effects

Treesearch

Craig M. Clemons; Daniel F. Caulfield; A. Jeffrey Giacomin

1999-10-01

In this study, the microstructure of injection-molded polypropylene reinforced with cellulose fiber was investigated. Scanning electron microscopy of the fracture surfaces and X-ray diffraction were used to investigate fiber orientation. The polypropylene matrix was removed by solvent extraction, and the lengths of the residual fibers were optically determined. Fiber...

Feasibility of Reducing the Fiber Content in Ultra-High-Performance Fiber-Reinforced Concrete under Flexure

PubMed Central

Park, Jung-Jun; Yoo, Doo-Yeol; Park, Gi-Joon; Kim, Sung-Wook

2017-01-01

In this study, the flexural behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) is examined as a function of fiber length and volume fraction. Straight steel fiber with three different lengths (lf) of 13, 19.5, and 30 mm and four different volume fractions (vf) of 0.5%, 1.0%, 1.5%, and 2.0% are considered. Test results show that post-cracking flexural properties of UHPFRC, such as flexural strength, deflection capacity, toughness, and cracking behavior, improve with increasing fiber length and volume fraction, while first-cracking properties are not significantly influenced by fiber length and volume fraction. A 0.5 vol % reduction of steel fiber content relative to commercial UHPFRC can be achieved without deterioration of flexural performance by replacing short fibers (lf of 13 mm) with longer fibers (lf of 19.5 mm and 30 mm). PMID:28772477

Polypropylene fiber reinforced microsilica concrete bridge deck overlay at Link River Bridge

DOT National Transportation Integrated Search

2000-02-01

In 1997 ODOT overlaid the Link River Bridge with microsilica concrete, reinforced with polypropylene fibers (FMC). The manufacturer claimed the fibers would reduce plastic shrinkage cracks and settlement cracking during the early life of the concrete...

Puncture-Healing Thermoplastic Resin Carbon-Fiber-Reinforced Composites

NASA Technical Reports Server (NTRS)

Grimsley, Brian W. (Inventor); Gordon, Keith L. (Inventor); Cano, Roberto J. (Inventor); Czabaj, Michael W. (Inventor); Siochi, Emilie J. (Inventor)

2015-01-01

A composite comprising a combination of a self-healing polymer matrix and a carbon fiber reinforcement is described. In one embodiment, the matrix is a polybutadiene graft copolymer matrix, such as polybutadiene graft copolymer comprising poly(butadiene)-graft-poly(methyl acrylate-co-acrylonitrile). A method of fabricating the composite is also described, comprising the steps of manufacturing a pre-impregnated unidirectional carbon fiber preform by wetting a plurality of carbon fibers with a solution, the solution comprising a self-healing polymer and a solvent, and curing the preform. A method of repairing a structure made from the composite of the invention is described. A novel prepreg material used to manufacture the composite of the invention is described.

Puncture-Healing Thermoplastic Resin Carbon-Fiber Reinforced Composites

NASA Technical Reports Server (NTRS)

Gordon, Keith L. (Inventor); Siochi, Emilie J. (Inventor); Grimsley, Brian W. (Inventor); Cano, Roberto J. (Inventor); Czabaj, Michael W. (Inventor)

2017-01-01

A composite comprising a combination of a self-healing polymer matrix and a carbon fiber reinforcement is described. In one embodiment, the matrix is a polybutadiene graft copolymer matrix, such as polybutadiene graft copolymer comprising poly(butadiene)-graft-poly(methyl acrylate-co-acrylonitrile). A method of fabricating the composite is also described, comprising the steps of manufacturing a pre-impregnated unidirectional carbon fiber preform by wetting a plurality of carbon fibers with a solution, the solution comprising a self-healing polymer and a solvent, and curing the preform. A method of repairing a structure made from the composite of the invention is described. A novel prepreg material used to manufacture the composite of the invention is described.

Processing and damage recovery of intrinsic self-healing glass fiber reinforced composites

NASA Astrophysics Data System (ADS)

Sordo, Federica; Michaud, Véronique

2016-08-01

Glass fiber reinforced composites with a self-healing, supramolecular hybrid network matrix were produced using a modified vacuum assisted resin infusion moulding process adapted to high temperature processing. The quality and fiber volume fraction (50%) of the obtained materials were assessed through microscopy and matrix burn-off methods. The thermo-mechanical properties were quantified by means of dynamic mechanical analysis, revealing very high damping properties compared to traditional epoxy-based glass fiber reinforced composites. Self-healing properties were assessed by three-point bending tests. A high recovery of the flexural properties, around 72% for the elastic modulus and 65% of the maximum flexural stress, was achieved after a resting period of 24 h at room temperature. Recovery after low velocity impact events was also visually observed. Applications for this intrinsic and autonomic self-healing highly reinforced composite material point towards semi-structural applications where high damping and/or integrity recovery after impact are required.

Experimental Investigation of Thermal Properties in Glass Fiber Reinforced with Aluminium

NASA Astrophysics Data System (ADS)

Irudaya raja, S. Joseph; Vinod Kumar, T.; Sridhar, R.; Vivek, P.

2017-03-01

A test method of a Guarded heat flow meter are used to measure the thermal conductivity of glass fiber and filled with a aluminum powder epoxy composites using an instrument in accordance with ASTM. This experimental study reveals that the incorporation of aluminum and glass fiber reinforced results in enhancement of thermal conductivity of epoxy resin and thereby improves its heat transfer capability. Fiber metal laminates are good candidates for advanced automobile structural applications due to their high categorical mechanical and thermal properties. The most consequential factor in manufacturing of these laminates is the adhesive bonding between aluminum and FRP layers. Here several glass-fiber reinforced aluminum were laminates with different proportion of bonding adhesion were been manufactured. It was observed that the damage size is more preponderant in laminates with poor interfacial adhesion compared to that of laminates with vigorous adhesion between aluminum and glass layers numerically calculated ones and it is found that the values obtained for various composite models using experimental testing method.

Finite deformation of incompressible fiber-reinforced elastomers: A computational micromechanics approach

NASA Astrophysics Data System (ADS)

Moraleda, Joaquín; Segurado, Javier; LLorca, Javier

2009-09-01

The in-plane finite deformation of incompressible fiber-reinforced elastomers was studied using computational micromechanics. Composite microstructure was made up of a random and homogeneous dispersion of aligned rigid fibers within a hyperelastic matrix. Different matrices (Neo-Hookean and Gent), fibers (monodisperse or polydisperse, circular or elliptical section) and reinforcement volume fractions (10-40%) were analyzed through the finite element simulation of a representative volume element of the microstructure. A successive remeshing strategy was employed when necessary to reach the large deformation regime in which the evolution of the microstructure influences the effective properties. The simulations provided for the first time "quasi-exact" results of the in-plane finite deformation for this class of composites, which were used to assess the accuracy of the available homogenization estimates for incompressible hyperelastic composites.

Method of preparing fiber reinforced ceramic material

NASA Technical Reports Server (NTRS)

Bhatt, Ramakrishna T. (Inventor)

1987-01-01

Alternate layers of mats of specially coated SiC fibers and silicon monotapes are hot pressed in two stages to form a fiber reinforced ceramic material. In the first stage a die is heated to about 600 C in a vacuum furnace and maintained at this temperature for about one-half hour to remove fugitive binder. In the second stage the die temperature is raised to about 1000 C and the layers are pressed at between 35 and 138 MPa. The resulting preform is placed in a reactor tube where a nitriding gas is flowed past the preform at 1100 to 1400 C to nitride the same.

Influence of triaxial braid denier on ribbon-based fiber reinforced dental composites.

PubMed

Karbhari, Vistasp M; Wang, Qiang

2007-08-01

The aim of the study was to compare the mechanical characteristics of two ultrahigh molecular weight polyethylene (UHMWPE) fiber-based triaxial braided reinforcements having different denier braider yarns used in fiber reinforced dental composites to elucidate differences in response and damage under flexural loading. Two commercially available triaxial braided reinforcing systems, differing in denier of the axial and braider yarns, using ultra high molecular weight polyethylene (UHMWPE) were used to reinforce rectangular bars towards the tensile surface which were tested in flexure. Mechanical characteristics including energy absorption were determined and results were compared based on Tukey post-test analysis and Weibull probability. Limited fatigue testing was also conducted for 100, 1000, and 10,000 cycles at a level of 75% of peak load. The effect of the braid denier on damage mechanisms was studied microscopically. The use of the triaxially braided ribbon as fiber reinforcement in the dental composite results in significant enhancement in flexural performance over that of the unreinforced dental composite (179% and 183% increase for the "thin" and "dense" braid reinforced specimens, respectively), with a fairly ductile, non-catastrophic post-peak response. With the exception of strain at peak load, there was very little difference between the performance from the two braid architectures. The intrinsic nature of the triaxial braid also results in very little decrease in flexural strength as a result of fatigue cycling at 75% of peak load. Use of the braids results in peak load levels which are substantially higher than those corresponding to points at which the dentin and unreinforced dental composites would fail. The total energy at peak load level is 56.8 and 60.7 times that at the level that dentin would fail if the reinforcement were not placed for the "thin" and "dense" reinforced braid reinforced composites, respectively. The research shows that in

Comparison of the fracture resistances of glass fiber mesh- and metal mesh-reinforced maxillary complete denture under dynamic fatigue loading.

PubMed

Im, So-Min; Huh, Yoon-Hyuk; Cho, Lee-Ra; Park, Chan-Jin

2017-02-01

The aim of this study was to investigate the effect of reinforcing materials on the fracture resistances of glass fiber mesh- and Cr-Co metal mesh-reinforced maxillary complete dentures under fatigue loading. Glass fiber mesh- and Cr-Co mesh-reinforced maxillary complete dentures were fabricated using silicone molds and acrylic resin. A control group was prepared with no reinforcement (n = 15 per group). After fatigue loading was applied using a chewing simulator, fracture resistance was measured by a universal testing machine. The fracture patterns were analyzed and the fractured surfaces were observed by scanning electron microscopy. After cyclic loading, none of the dentures showed cracks or fractures. During fracture resistance testing, all unreinforced dentures experienced complete fracture. The mesh-reinforced dentures primarily showed posterior framework fracture. Deformation of the all-metal framework caused the metal mesh-reinforced denture to exhibit the highest fracture resistance, followed by the glass fiber mesh-reinforced denture ( P <.05) and the control group ( P <.05). The glass fiber mesh-reinforced denture primarily maintained its original shape with unbroken fibers. River line pattern of the control group, dimples and interdendritic fractures of the metal mesh group, and radial fracture lines of the glass fiber group were observed on the fractured surfaces. The glass fiber mesh-reinforced denture exhibits a fracture resistance higher than that of the unreinforced denture, but lower than that of the metal mesh-reinforced denture because of the deformation of the metal mesh. The glass fiber mesh-reinforced denture maintains its shape even after fracture, indicating the possibility of easier repair.

Chemical Treatment of Waste Abaca for Natural Fiber-Reinforced Geopolymer Composite

PubMed Central

Malenab, Roy Alvin J.; Ngo, Janne Pauline S.; Promentilla, Michael Angelo B.

2017-01-01

The use of natural fibers in reinforced composites to produce eco-friendly materials is gaining more attention due to their attractive features such as low cost, low density and good mechanical properties, among others. This work thus investigates the potential of waste abaca (Manila hemp) fiber as reinforcing agent in an inorganic aluminosilicate material known as geopolymer. In this study, the waste fibers were subjected to different chemical treatments to modify the surface characteristics and to improve the adhesion with the fly ash-based geopolymer matrix. Definitive screening design of experiment was used to investigate the effect of successive chemical treatment of the fiber on its tensile strength considering the following factors: (1) NaOH pretreatment; (2) soaking time in aluminum salt solution; and (3) final pH of the slurry. The results show that the abaca fiber without alkali pretreatment, soaked for 12 h in Al2(SO4)3 solution and adjusted to pH 6 exhibited the highest tensile strength among the treated fibers. Test results confirmed that the chemical treatment removes the lignin, pectin and hemicellulose, as well as makes the surface rougher with the deposition of aluminum compounds. This improves the interfacial bonding between geopolymer matrix and the abaca fiber, while the geopolymer protects the treated fiber from thermal degradation. PMID:28772936

[Fusion implants of carbon fiber reinforced plastic].

PubMed

Früh, H J; Liebetrau, A; Bertagnoli, R

2002-05-01

Carbon fiber reinforced plastics (CFRP) are used in the medical field when high mechanical strength, innovative design, and radiolucency (see spinal fusion implants) are needed. During the manufacturing process of the material CFRP carbon fibers are embedded into a resin matrix. This resin material could be thermoset (e.g., epoxy resin EPN/DDS) or thermoplastic (e.g., PEAK). CFRP is biocompatible, radiolucent, and has higher mechanical capabilities compared to other implant materials. This publication demonstrates the manufacturing process of fusion implants made of a thermoset matrix system using a fiber winding process. The material has been used clinically since 1994 for fusion implants of the cervical and lumbar spine. The results of the fusion systems CORNERSTONE-SR C (cervical) and UNION (lumbar) showed no implant-related complications. New implant systems made of this CFRP material are under investigation and are presented.

Anomaly detection of microstructural defects in continuous fiber reinforced composites

NASA Astrophysics Data System (ADS)

Bricker, Stephen; Simmons, J. P.; Przybyla, Craig; Hardie, Russell

2015-03-01

Ceramic matrix composites (CMC) with continuous fiber reinforcements have the potential to enable the next generation of high speed hypersonic vehicles and/or significant improvements in gas turbine engine performance due to their exhibited toughness when subjected to high mechanical loads at extreme temperatures (2200F+). Reinforced fiber composites (RFC) provide increased fracture toughness, crack growth resistance, and strength, though little is known about how stochastic variation and imperfections in the material effect material properties. In this work, tools are developed for quantifying anomalies within the microstructure at several scales. The detection and characterization of anomalous microstructure is a critical step in linking production techniques to properties, as well as in accurate material simulation and property prediction for the integrated computation materials engineering (ICME) of RFC based components. It is desired to find statistical outliers for any number of material characteristics such as fibers, fiber coatings, and pores. Here, fiber orientation, or `velocity', and `velocity' gradient are developed and examined for anomalous behavior. Categorizing anomalous behavior in the CMC is approached by multivariate Gaussian mixture modeling. A Gaussian mixture is employed to estimate the probability density function (PDF) of the features in question, and anomalies are classified by their likelihood of belonging to the statistical normal behavior for that feature.

Well-ordered polymer nano-fibers with self-cleaning property by disturbing crystallization process

NASA Astrophysics Data System (ADS)

Yang, Qin; Luo, Zhuangzhu; Tan, Sheng; Luo, Yimin; Wang, Yunjiao; Zhang, Zhaozhu; Liu, Weimin

2014-07-01

Bionic self-cleaning surfaces with well-ordered polymer nano-fibers are firstly fabricated by disturbing crystallization during one-step coating-curing process. Orderly thin (100 nm) and long (5-10 μm) polymer nano-fibers with a certain direction are fabricated by external macroscopic force ( F blow) interference introduced by H2 gas flow, leading to superior superhydrophobicity with a water contact angle (WCA) of 170° and a water sliding angle (WSA) of 0-1°. In contrast, nano-wires and nano-bridges (1-8 μm in length/10-80 nm in width) are generated by "spinning/stretching" under internal microscopic force ( F T) interference due to significant temperature difference in the non-uniform cooling medium. The findings provide a novel theoretical basis for controllable polymer "bionic lotus" surface and will further promote practical application in many engineering fields such as drag-reduction and anti-icing.

Carbon Fiber Reinforced Ceramic Composites for Propulsion Applications

NASA Technical Reports Server (NTRS)

Shivakumar, Kunigal; Argade, Shyam

2003-01-01

This report presents a critical review of the processing techniques for fabricating continuous fiber-reinforced CMCs for possible applications at elevated temperatures. Some of the issues affecting durability of the composite materials such as fiber coatings and cracking of the matrix because of shrinkage in PIP-process are also examined. An assessment of the potential inexpensive processes is also provided. Finally three potential routes of manufacturing C/SiC composites using a technology that NC A&T developed for carbon/carbon composites are outlined. Challenges that will be encountered are also listed.

Graphite fiber reinforced structure for supporting machine tools

DOEpatents

Knight, Jr., Charles E.; Kovach, Louis; Hurst, John S.

1978-01-01

Machine tools utilized in precision machine operations require tool support structures which exhibit minimal deflection, thermal expansion and vibration characteristics. The tool support structure of the present invention is a graphite fiber reinforced composite in which layers of the graphite fibers or yarn are disposed in a 0/90.degree. pattern and bonded together with an epoxy resin. The finished composite possesses a low coefficient of thermal expansion and a substantially greater elastic modulus, stiffness-to-weight ratio, and damping factor than a conventional steel tool support utilized in similar machining operations.

Effect of short glass fiber/filler particle proportion on flexural and diametral tensile strength of a novel fiber-reinforced composite.

PubMed

Fonseca, Rodrigo Borges; de Almeida, Letícia Nunes; Mendes, Gustavo Adolfo Martins; Kasuya, Amanda Vessoni Barbosa; Favarão, Isabella Negro; de Paula, Marcella Silva

2016-01-01

To evaluate the effect of glass fiber/filler particles proportion on flexural strength and diametral tensile strength of an experimental fiber-reinforced composite. Four experimental groups (N=10) were created using an experimental short fiber-reinforced composite, having as a factor under study the glass fiber (F) and filler particle (P) proportion: F22.5/P55 with 22.5 wt% of fiber and 55 wt% of filler particles; F25/P52.5 with 25 wt% of fiber and 52.5 wt% of filler particles; F27.5/P50 with 27.5 wt% of fiber and 50 wt% of filler particles; F30/P47.5 with 30 wt% of fiber and 47.5 wt% of filler particles. The experimental composite was made up by a methacrylate-based resin (50% Bis-GMA and 50% TEGDMA). Specimens were prepared for Flexural Strength (FS) (25 mm × 2 mm × 2 mm) and for Diametral Tensile Strength (DTS) (3×6 Ø mm) and tested at 0.5 mm/min in a universal testing machine. The results (in MPa) showed significance (different superscript letters mean statistical significant difference) for FS (p<0.009) and DTS (p<0.001)--FS results: F22.5/P55: 217.24±20.64(B); F25/P52.5: 245.77±26.80(AB); F27.5/P50: 246.88±32.28(AB); F30/P47.5: 259.91±26.01(A). DTS results: F22.5/P55: 21.82±4.42(B); F25/P52.5: 22.00±7.40(B); F27.5/P50: 18.63±4.41(B); F30/P47.5: 31.05±2.97(A). In SEM analysis, areas without fiber reinforcement demonstrated to be more prone to the presence of bubbles and crack development. The group F30/P47.5 showed areas with a great quantity of fibers without empty spaces for crack propagation. Increasing fiber content results in higher flexural and diametral tensile strength of an experimental composite reinforced with glass fibers. Copyright © 2015 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Fiber-reinforced concretes with a high fiber volume fraction — a look in future. Can a design determine the fiber amount in concrete in real time in every part of a structure in production?

NASA Astrophysics Data System (ADS)

Tepfers, R.

2010-09-01

In near future, when the control of the load-bearing capacity of fiber-only-reinforced concrete members will be safely guaranteed, the deletion of the ordinary continuous steel reinforcing bars might be possible. For the time being, it is difficult to change the fiber amount during the casting with today's techniques. Therefore, the fiber concentration has to be determined by the maximum tensile stress in concrete structural members, resulting in an unnecessary fiber addition in compressed zones. However, if the right amount of fibers could be regulated and added to concrete in real time at the pump outlet, a future vision could be to design and produce a structure by using FEM-controlled equipment. The signals from calculation results could be transmitted to a concrete casting system for addition of a necessary amount of fibers to take care of the actual tensile stresses in the right position in the structure. The casting location could be determined by using a GPS for positioning the pump outlet for targeting the casting location horizontally and a laser vertically. The addition of fibers to concrete at the outlet of a concrete pump and proportioning them there according to the actual needs of the stress situation in a structure, given by a FEM analysis in real time, is a future challenge. The FEM analysis has to be based on material properties of fiber-only-reinforced concrete. This means that the resistance and stiffness of different-strength concrete members with a varying fiber content has to be determined in tests and conveyed to the FEM analysis. The FEM analysis has to be completed before the casting and controlled. Then it can be used as the base for adding a correct amount of fibers to concrete in every part of the structure. Thus, a system for introducing a correct amount of fibers into concrete has to be developed. The fibers have to be added at the outlet of concrete pump. Maybe a system to shotcrete concrete with electronically controlled fiber

Tribological study of non-asbestos fiber reinforced phenolic composites for braking applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gopal, P.; Dharani, L.R.; Blum, F.D.

A cashew modified phenolic resin was used as the binder to prepare several different nonasbestos fiber reinforced composite friction materials. Friction-wear tests were conducted at various loads, speeds and temperatures on a Chase friction testing machine. The fade and wear characteristics of glass and carbon fiber reinforced friction materials were studied. The wear rates of hybrid composites containing Kevlar{reg_sign} (registered trademark of E.I. duPont de Nemours) pulp were compared to those of control composites without Kevlar{reg_sign} pulp.

Fiber reinforced glasses and glass-ceramics for high performance applications

NASA Technical Reports Server (NTRS)

Prewo, K. M.; Brennan, J. J.; Layden, G. K.

1986-01-01

The development of fiber reinforced glass and glass-ceramic matrix composites is described. The general concepts involved in composite fabrication and resultant composite properties are given for a broad range of fiber and matrix combinations. It is shown that composite materials can be tailored to achieve high levels of toughness, strength, and elastic stiffness, as well as wear resistance and dimensional stability.

High-performance fiber-reinforced concrete in a bridge deck.

DOT National Transportation Integrated Search

2005-01-01

The purpose of this research was to compare the performance of high-performance fiber-reinforced concrete (FRC) with that of conventional concrete in a bridge deck. FRC is expected to increase toughness, provide enhanced residual strength, and minimi...

Development and performance evaluation of fiber reinforced polymer bridge.

DOT National Transportation Integrated Search

2014-03-01

Fiber reinforced polymers (FRP) have become more popular construction materials in the last decade due to the reduction of : material costs. The installation and performance evaluation of the first FRP-wrapped balsa wood bridge in Louisiana is descri...

RTM simulations and experiments for fiber-reinforced turbine blades forming

NASA Astrophysics Data System (ADS)

Nguyen, Tuan Linh; Marchand, Christophe

2018-05-01

The one-shot (full part) forming of tidal turbine blades by RTM (Resin Transfer Molding) process is a complex process due to the complexity of reinforcements and geometry of blades. In this work, beside the experimental tests which have been realized using IRT JV high capacity machines, the RTM simulations using Moldex3D RTM software have been carried out. First of all, simulations have been done on a 1/7th scale part in order to determine the best injection strategy. Different tested strategies vary by the disposition of injection points (Inlet)/vacuum points (Outlet). Then, the chosen strategy has been applied on the full scale part (˜ 7m length) of high thickness with more complex reinforcement draping. In both cases, the stage of meshing is important to take into account the draping plan with different fiber orientation and fiber types. Attention should be paid on the neck of the blade as the structure of reinforcement changes. A sensitivity study of different parameters (permeability, pressure, temperature) has been then done to understand their influence on the injection time. The permeability which lies to the choice of reinforcement type and fiber volume fraction plays an important role. As the thickness of the part is high, an experimental campaign for measuring the 3D permeability is required. Among the process controllable parameters, the pressure seems the fastest way to reduce the injection time. However, increasing the injection pressure (or the vacuum) could deform the reinforcement. Moreover, the maximal pressure depends on the machine capacity. The influence of temperature shows the thermo-dependence of resin viscosity, the injection time thus decreases as the temperature increases. Nevertheless, the gel time is more limited for injection stage if the resin is heated too much.

Bioactive Glass Fiber Reinforced Starch-Polycaprolactone Composite for Bone Applications

NASA Astrophysics Data System (ADS)

Jukola, H.; Nikkola, L.; Gomes, M. E.; Chiellini, F.; Tukiainen, M.; Kellomäki, M.; Chiellini, E.; Reis, R. L.; Ashammakhi, N.

2008-02-01

For bone regeneration and repair, combinations of different materials are often needed. Biodegradable polymers are often combined with osteoconductive materials, such as bioactive glass (BaG), which can also improve the mechanical properties of the composite. The aim of this study was to develop and characterize BaG fiber-reinforced starch-poly-ɛ-caprolactone (SPCL) composite. Sheets of SPCL (30/70 wt%) were produced using single-screw extrusion. They were then cut and compression molded in layers with BaG fibers to form composite structures of different combinations. Thermal, mechanical, and degradation properties of the composites were studied. The actual amount of BaG in the composites was determined using combustion tests. A strong endothermic peak indicating melting at about 56 °C was observed by differential scanning calorimetry (DSC) analysis. Thermal gravimetry analysis (TGA) showed that thermal decomposition of SPCL started at 325 °C with the decomposition of starch and continued at 400 °C with the degradation of polycaprolactone (PCL). Initial mechanical properties of the reinforced composites were at least 50% better than the properties of the non-reinforced composites. However, the mechanical properties of the composites after two weeks of hydrolysis were comparable to those of the non-reinforced samples. During the six weeks' hydrolysis the mass of the composites had decreased only by about 5%. The amount of glass in the composites remained the same for the six-week period of hydrolysis. In conclusion, it is possible to enhance the initial mechanical properties of SPCL by reinforcing it with BaG fibers. However, the mechanical properties of the composites are only sufficient for use as filler material and they need to be further improved to allow long-lasting bone applications.

Bioactive Glass Fiber Reinforced Starch-Polycaprolactone Composite for Bone Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jukola, H.; Nikkola, L.; Tukiainen, M.

2008-02-15

For bone regeneration and repair, combinations of different materials are often needed. Biodegradable polymers are often combined with osteoconductive materials, such as bioactive glass (BaG), which can also improve the mechanical properties of the composite. The aim of this study was to develop and characterize BaG fiber-reinforced starch-poly-{epsilon}-caprolactone (SPCL) composite. Sheets of SPCL (30/70 wt%) were produced using single-screw extrusion. They were then cut and compression molded in layers with BaG fibers to form composite structures of different combinations. Thermal, mechanical, and degradation properties of the composites were studied. The actual amount of BaG in the composites was determined usingmore » combustion tests. A strong endothermic peak indicating melting at about 56 deg. C was observed by differential scanning calorimetry (DSC) analysis. Thermal gravimetry analysis (TGA) showed that thermal decomposition of SPCL started at 325 deg. C with the decomposition of starch and continued at 400 deg. C with the degradation of polycaprolactone (PCL). Initial mechanical properties of the reinforced composites were at least 50% better than the properties of the non-reinforced composites. However, the mechanical properties of the composites after two weeks of hydrolysis were comparable to those of the non-reinforced samples. During the six weeks' hydrolysis the mass of the composites had decreased only by about 5%. The amount of glass in the composites remained the same for the six-week period of hydrolysis. In conclusion, it is possible to enhance the initial mechanical properties of SPCL by reinforcing it with BaG fibers. However, the mechanical properties of the composites are only sufficient for use as filler material and they need to be further improved to allow long-lasting bone applications.« less

Study on Energy Absorption Capacity of Steel-Polyester Hybrid Fiber Reinforced Concrete Under Uni-axial Compression

NASA Astrophysics Data System (ADS)

Chella Gifta, C.; Prabavathy, S.

2018-05-01

This work presents the energy absorption capacity of hybrid fiber reinforced concrete made with hooked end steel fibers (0.5 and 0.75%) and straight polyester fibers (0.5, 0.8, 1.0 and 2.0%). Compressive toughness (energy absorption capacity) under uni-axial compression was evaluated on 100 × 200 mm size cylindrical specimens with varying steel and polyester fiber content. Efficiency of the hybrid fiber reinforcement is studied with respect to fiber type, size and volume fractions in this investigation. The vertical displacement under uni-axial compression was measured under the applied loads and the load-deformation curves were plotted. From these curves the toughness values were calculated and the results were compared with steel and polyester as individual fibers. The hybridization of 0.5% steel + 0.5% polyester performed well in post peak region due to the addition of polyester fibers with steel fibers and the energy absorption value was 23% greater than 0.5% steel FRC. Peak stress values were also higher in hybrid series than single fiber and based on the results it is concluded that hybrid fiber reinforcement improves the toughness characteristics of concrete without affecting workability.

Accelerated Creep Testing of High Strength Aramid Webbing

NASA Technical Reports Server (NTRS)

Jones, Thomas C.; Doggett, William R.; Stnfield, Clarence E.; Valverde, Omar

2012-01-01

A series of preliminary accelerated creep tests were performed on four variants of 12K and 24K lbf rated Vectran webbing to help develop an accelerated creep test methodology and analysis capability for high strength aramid webbings. The variants included pristine, aged, folded and stitched samples. This class of webbings is used in the restraint layer of habitable, inflatable space structures, for which the lifetime properties are currently not well characterized. The Stepped Isothermal Method was used to accelerate the creep life of the webbings and a novel stereo photogrammetry system was used to measure the full-field strains. A custom MATLAB code is described, and used to reduce the strain data to produce master creep curves for the test samples. Initial results show good correlation between replicates; however, it is clear that a larger number of samples are needed to build confidence in the consistency of the results. It is noted that local fiber breaks affect the creep response in a similar manner to increasing the load, thus raising the creep rate and reducing the time to creep failure. The stitched webbings produced the highest variance between replicates, due to the combination of higher local stresses and thread-on-fiber damage. Large variability in the strength of the webbings is also shown to have an impact on the range of predicted creep life.

Comparison and Analysis on Mechanical Property and Machinability about Polyetheretherketone and Carbon-Fibers Reinforced Polyetheretherketone.

PubMed

Ji, Shijun; Sun, Changrui; Zhao, Ji; Liang, Fusheng

2015-07-07

The aim of this paper is to compare the mechanical property and machinability of Polyetheretherketone (PEEK) and 30 wt% carbon-fibers reinforced Polyetheretherketone (PEEK CF 30). The method of nano-indentation is used to investigate the microscopic mechanical property. The evolution of load with displacement, Young's modulus curves and hardness curves are analyzed. The results illustrate that the load-displacement curves of PEEK present better uniformity, and the variation of Young's modulus and hardness of PEEK both change smaller at the experimental depth. The machinability between PEEK and PEEK CF 30 are also compared by the method of single-point diamond turning (SPDT), and the peak-to-valley value (PV) and surface roughness (Ra) are obtained to evaluate machinability of the materials after machining. The machining results show that PEEK has smaller PV and Ra, which means PEEK has superior machinability.

Mechanically Strong Graphene/Aramid Nanofiber Composite Electrodes for Structural Energy and Power.

PubMed

Kwon, Se Ra; Harris, John; Zhou, Tianyang; Loufakis, Dimitrios; Boyd, James G; Lutkenhaus, Jodie L

2017-07-25

Structural energy and power systems offer both mechanical and electrochemical performance in a single multifunctional platform. These are of growing interest because they potentially offer reduction in mass and/or volume for aircraft, satellites, and ground transportation. To this end, flexible graphene-based supercapacitors have attracted much attention due to their extraordinary mechanical and electrical properties, yet they suffer from poor strength. This problem may be exacerbated with the inclusion of functional guest materials, often yielding strengths of <15 MPa. Here, we show that graphene paper supercapacitor electrodes containing aramid nanofibers as guest materials exhibit extraordinarily high tensile strength (100.6 MPa) and excellent electrochemical stability. This is achieved by extensive hydrogen bonding and π-π interactions between the graphene sheets and aramid nanofibers. The trade-off between capacitance and mechanical properties is evaluated as a function of aramid nanofiber loading, where it is shown that these electrodes exhibit multifunctionality superior to that of other graphene-based supercapacitors, nearly rivaling those of graphene-based pseudocapacitors. We anticipate these composite electrodes to be a starting point for structural energy and power systems that harness the mechanical properties of aramid nanofibers.

Interfacial adhesion improvement in carbon fiber/carbon nanotube reinforced hybrid composites by the application of a reactive hybrid resin initiated by gamma irradiation

NASA Astrophysics Data System (ADS)

Szebényi, G.; Faragó, D.; Lámfalusi, Cs.; Göbl, R.

2018-04-01

Interfacial adhesion is a key factor in composite materials. The effective co-working of the reinforcing materials and matrix is essential for the proper load transfer between them, and to achieve the desired reinforcing effect. In case of nanocomposites, especially carbon nanotube (CNT) reinforced nanocomposites the adhesion between the CNTs and the polymer matrix is poor. To improve the interfacial adhesion and exploit the reinforcing effect of these nanoparticles a two step curable epoxy (EP)/vinylester (VE) hybrid resin system was developed where the EP is cured using hardener in the first step, during the composite production, and in the second step the curing of the VE is initiated by gamma irradiation, which also activates the reinforcing materials and the cured matrix component. A total of six carbon fiber reinforced composite systems were compared with neat epoxy and EP/VE hybrid matrices with and without chemical initiator and MWCNT nano-reinforcement. The effect of gamma irradiation was investigated at four absorbed dose levels. According to our three point bending and interlaminar shear test results the adhesion has improved between all constituents of the composite system. It was demonstrated that gamma irradiation has beneficial effect on the static mechanical, especially interlaminar properties of both micro- and nanocomposites in terms of modulus, strength and interlaminar shear strength.

Feasibility of Reducing the Fiber Content in Ultra-High-Performance Fiber-Reinforced Concrete under Flexure.

PubMed

Park, Jung-Jun; Yoo, Doo-Yeol; Park, Gi-Joon; Kim, Sung-Wook

2017-01-28

In this study, the flexural behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) is examined as a function of fiber length and volume fraction. Straight steel fiber with three different lengths ( l f ) of 13, 19.5, and 30 mm and four different volume fractions ( v f ) of 0.5%, 1.0%, 1.5%, and 2.0% are considered. Test results show that post-cracking flexural properties of UHPFRC, such as flexural strength, deflection capacity, toughness, and cracking behavior, improve with increasing fiber length and volume fraction, while first-cracking properties are not significantly influenced by fiber length and volume fraction. A 0.5 vol % reduction of steel fiber content relative to commercial UHPFRC can be achieved without deterioration of flexural performance by replacing short fibers ( l f of 13 mm) with longer fibers ( l f of 19.5 mm and 30 mm).

Ceramic fiber-reinforced monoclinic celsian phase glass-ceramic matrix composite material

NASA Technical Reports Server (NTRS)

Bansal, Narottam P. (Inventor); Dicarlo, James A. (Inventor)

1994-01-01

A hyridopolysilazane-derived ceramic fiber reinforced monoclinic celsian phase barium aluminum silicate glass-ceramic matrix composite material is prepared by ball-milling an aqueous slurry of BAS glass powder and fine monoclinic celsian seeds. The fibers improve the mechanical strength and fracture toughness and with the matrix provide superior dielectric properties.

Graphite fiber reinforced thermoplastic resins

NASA Technical Reports Server (NTRS)

Novak, R. C.

1975-01-01

Mechanical properties of neat resin samples and graphite fiber reinforced samples of thermoplastic resins were characterized with particular emphasis directed to the effects of environmental exposure (humidity, temperature and ultraviolet radiation). Tensile, flexural, interlaminar shear, creep and impact strengths were measured for polysulfone, polyarylsulfone and a state-of-the-art epoxy resin samples. In general, the thermoplastic resins exhibited environmental degradation resistance equal to or superior to the reference epoxy resin. Demonstration of the utility and quality of a graphite/thermoplastic resin system was accomplished by successfully thermoforming a simulated compressor blade and a fan exit guide vane.

Comparison of the fracture resistances of glass fiber mesh- and metal mesh-reinforced maxillary complete denture under dynamic fatigue loading

PubMed Central

2017-01-01

PURPOSE The aim of this study was to investigate the effect of reinforcing materials on the fracture resistances of glass fiber mesh- and Cr–Co metal mesh-reinforced maxillary complete dentures under fatigue loading. MATERIALS AND METHODS Glass fiber mesh- and Cr–Co mesh-reinforced maxillary complete dentures were fabricated using silicone molds and acrylic resin. A control group was prepared with no reinforcement (n = 15 per group). After fatigue loading was applied using a chewing simulator, fracture resistance was measured by a universal testing machine. The fracture patterns were analyzed and the fractured surfaces were observed by scanning electron microscopy. RESULTS After cyclic loading, none of the dentures showed cracks or fractures. During fracture resistance testing, all unreinforced dentures experienced complete fracture. The mesh-reinforced dentures primarily showed posterior framework fracture. Deformation of the all-metal framework caused the metal mesh-reinforced denture to exhibit the highest fracture resistance, followed by the glass fiber mesh-reinforced denture (P<.05) and the control group (P<.05). The glass fiber mesh-reinforced denture primarily maintained its original shape with unbroken fibers. River line pattern of the control group, dimples and interdendritic fractures of the metal mesh group, and radial fracture lines of the glass fiber group were observed on the fractured surfaces. CONCLUSION The glass fiber mesh-reinforced denture exhibits a fracture resistance higher than that of the unreinforced denture, but lower than that of the metal mesh-reinforced denture because of the deformation of the metal mesh. The glass fiber mesh-reinforced denture maintains its shape even after fracture, indicating the possibility of easier repair. PMID:28243388