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Sample records for fiber reinforced polyester

  1. Tensile Strength of Natural Fiber Reinforced Polyester Composite

    NASA Astrophysics Data System (ADS)

    Ismail, Al Emran; Awang, Muhd. Khairudin; Sa'at, Mohd Hisham

    2007-05-01

    Nowadays, increasing awareness of replacing synthetic fiber such as glass fiber has emerged due to environmental problems and pollutions. Automotive manufacturers also seek new material especially biodegradable material to be non-load bearing application parts. This present work discussed on the effect of silane treatment on coir fiber reinforced composites. From the results of tensile tests, fibers treated with silane have attained maximum material stiffness. However, to achieve maximum ultimate tensile strength and strain at failure performances, untreated fibers work very well through fiber bridging and internal friction between fiber and polymeric matrix. Scanning electron microscope (SEM) observations have coincided with these results.

  2. Modification of polyester resins during molding of glass-fiber-reinforced plastics

    NASA Astrophysics Data System (ADS)

    Yakushin, V.; Jansons, J.; Bulmanis, V.; Cabulis, U.; Bulmanis, A.

    2013-11-01

    The effect of addition of two new urethane prepolymers on the mechanical properties of unsaturated polyester resins and glass-fiber-reinforced plastics based on them is investigated. The effect of concentration of these additives on the elastic modulus, elongation at break, and flexural strength of hardened orthophthalic resins is evaluated. A significant increase in the strength of the binders and glass-fiber-reinforced plastics (GFRPs) based on them is observed upon adding urethane prepolymers to the resins. The properties of laminated and randomly reinforced glass-fiber plastics with the modified orthophthalic resins are compared with those of similar GFRPs based on popular brands of industrial resins.

  3. 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.

  4. Effect of polyester fiber reinforcement on the mechanical properties of interim fixed partial dentures

    PubMed Central

    Gopichander, N.; Halini Kumarai, K.V.; Vasanthakumar, M.

    2015-01-01

    Background Different reinforcements currently available for interim fixed partial denture (FPD) materials do not provide the ideal strength for long-term use. Therefore, the aim of this investigation was to develop a more ideal provisional material for long-term use with better mechanical properties. This study evaluated the effectiveness of polyester fiber reinforcement on different interim FPD materials. Methods Thirty resin-bonded FPDs were constructed from three provisional interim FPD materials. Specimens were tested with a universal testing machine (UTM). The modulus of elasticity and flexural strength were recorded in MPa. The compressive strength and degree of deflection were calculated from the obtained values, and a two-way analysis of variance (ANOVA) was used to determine the significance. Results The polyester fiber reinforcement increased the mechanical properties. The modulus of elasticity for heat-polymerized polymethyl methacrylate (PMMA) was 624 MPa, compared to 700.2 MPa for the reinforced heat-cured sample. The flexural strengths of the bis-acrylic and cold-polymerized reinforced samples increased significantly to 2807 MPa and 979.86 MPa, respectively, compared to the nonreinforced samples. The mean compressive strength of the reinforced cold-polymerized PMMA samples was 439.17 MPa; and for the reinforced heat-polymerized PMMA samples, it was 1117.41 MPa. The degree of deflection was significantly greater (P < 0.05) in the reinforced bis-acrylic sample (5.03 MPa), compared with the nonreinforced bis-acrylic sample (2.95 MPa). Conclusion Within the limitations of this study, polyester fiber reinforcements improved the mechanical properties of heat-polymerized PMMA, cold-polymerized PMMA, and bis-acrylic provisional FPD materials. PMID:26644754

  5. Hemp-Fiber-Reinforced Unsaturated Polyester Composites: Optimization of Processing and Improvement of Interfacial Adhesion

    SciTech Connect

    Qui, Renhui; Ren, Xiaofeng; Fifield, Leonard S.; Simmons, Kevin L.; Li, Kaichang

    2011-02-25

    The processing variables for making hemp-fiber-reinforced unsaturated polyester (UPE) composites were optimized through orthogonal experiments. It was found that the usage of initiator, methyl ethyl ketone peroxide, had the most significant effect on the tensile strength of the composites. The treatment of hemp fibers with a combination of 1, 6-diisocyanatohexane (DIH) and 2-hydroxylethyl acrylate (HEA) significantly increased tensile strength, flexural modulus of rupture and flexural modulus of elasticity, and water resistance of the resulting hemp-UPE composites. FTIR spectra revealed that DIH and HEA were covalently bonded to hemp fibers. Scanning electronic microscopy graphs of the fractured hemp-UPE composites demonstrated that treatment of hemp fibers with a combination of DIH and HEA greatly improved the interfacial adhesion between hemp fibers and UPE. The mechanism of improving the interfacial adhesion is proposed.

  6. Kenaf-glass fiber reinforced unsaturated polyester hybrid composites: Tensile properties

    NASA Astrophysics Data System (ADS)

    Zhafer, S. F.; Rozyanty, A. R.; Shahnaz, S. B. S.; Musa, L.; Zuliahani, A.

    2016-07-01

    The use of natural fibers in composite is rising in recent years due their lightweight, non-abrasive, combustible, non-toxic, low cost and biodegradable properties. However, in comparison with synthetic fibers, the mechanical properties of natural fibers are lower. Therefore, the inclusion of synthetic fibers could improve the mechanical performance of natural fiber based composites. In this study, kenaf bast fiber and glass fiber at different weight percentage loading were used as reinforcement to produce hybrid composites. Unsaturated polyester (UP) resin was used as matrix and hand lay-up process was performed to apply the UP resin on the hybrid kenaf bast/glass fiber composite. Effect of different fiber loading on tensile strength, tensile modulus and elongation at break of the hybrid composite was studied. It has been found that the highest value of tensile strength and modulus was achieved at 10 wt.% kenaf/10 wt.% glass fiber loading. It was concluded that addition of glass fiber has improved the tensile properties of kenaf bast fiber based UP composites.

  7. The effect of woven and non-woven fiber structure on mechanical properties polyester composite reinforced kenaf

    NASA Astrophysics Data System (ADS)

    Ratim, S.; Bonnia, N. N.; Surip, S. N.

    2012-07-01

    The effects of woven and non-woven kenaf fiber on mechanical properties of polyester composites were studied at different types of perform structures. Composite polyester reinforced kenaf fiber has been prepared via hand lay-up process by varying fiber forms into plain weave, twill and mats structure. The reinforcing efficiency of different fiber structure was compared with control of unreinforced polyester sample. It was found that the strength and stiffness of the composites are largely affected by fiber structure. A maximum value for tensile strength of composite was obtained for twill weave pattern of fiber structure while no significant different for plain weave and mat structure. The elastic modulus of composite has shown some improvement on plain and twill weave pattern. Meanwhile, lower value of modulus elasticity achieved by mats structure composite as well as control sample. The modulus of rupture and impact resistance were also analyzed. The improvement of modulus of rupture value can be seen on plain and twill weave pattern. However impact resistance doesn't show significant improvement in all types of structure except for mat fiber. The mechanical properties of kenaf fiber reinforced polyester composite found to be increased with woven and non-woven fiber structures in composite.

  8. Development and Evaluation of Novel Coupling Agents for Kenaf-Fiber-Reinforced Unsaturated Polyester Composites

    NASA Astrophysics Data System (ADS)

    Ren, Xiaofeng

    Natural fibers are gaining popularity as reinforcement materials for thermoset resins over the last two decades. Natural fibers are inexpensive, abundant, renewable and environmentally friendly. Kenaf fibers are one of the natural fibers that can potentially be used for reinforcing unsaturated polyester (UPE). As a polymer matrix, UPE enjoys a 40% market share of all the thermoset composites. This widespread application is due to many favorable characteristics including low cost, ease of cure at room temperature, ease of molding, a good balance of mechanical, electrical and chemical properties. One of the barriers for the full utilization of the kenaf fiber reinforced UPE composites, however, is the poor interfacial adhesion between the natural fibers and the UPE resins. The good interfacial adhesion between kenaf fibers and UPE matrix is essential for generating the desired properties of kenaf-UPE composites for most of the end applications. Use of a coupling agent is one of the most effective ways of improving the interfacial adhesion. In this study, six novel effective coupling agents were developed and investigated for kenaf-UPE composites: DIH-HEA, MFA, NMA, AESO-DIH, AESO-MDI, and AESO-PMDI. All the coupling agents were able to improve the interfacial adhesion between kanaf and UPE resins. The coupling agents were found to significantly enhance the flexural properties and water resistance of the kenaf-UPE composites. Fourier transform infrared spectroscopy (FTIR) confirmed all the coupling agents were covalently bonded onto kenaf fibers. Scanning electron microscopy (SEM) images of the composites revealed the improved interfacial adhesion between kanaf fibers and UPE resins.

  9. Polyester composites reinforced with corona-treated fibers from pine, eucalyptus and sugarcane bagasse

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study aims to evaluate plant fibers that were surface activated with NaOH and corona discharge before incorporating in ortho unsaturated polyester-based fiber composites. It demonstrates the potential use of lignocellulosic particles, especially eucalyptus that presented the higher values for a...

  10. Erosive wear characteristics of multi-fiber reinforced polyester under different operating conditions

    NASA Astrophysics Data System (ADS)

    Debnath, U. K.; Chowdhury, M. A.; Nuruzzaman, D. M.

    2016-02-01

    Composite materials are used in a wide range of applications. The erosion properties of combination of glass, jute and carbon fiber-reinforced polyester were analyzed in this study. Randomly-shaped silica (SiO2) particles of various sizes (300-355μm, 355-500μm, and 500- 600μm) were selected as the erosive element. Impingement angles between 15-90°, impingement velocities between 30-50 m/sec, and stand-off distances of 15-25 mm at ambient temperature were selected. During experiment, the maximum erosion of the tested composite occurred at 60° impingement angle, indicating a semi-ductile nature of the test material. Erosion increased with impact velocity and decreased with stand-off distance. In a dimensional analysis, erosion efficiency (η) and the relationship between friction and erosion were established. Test results were evaluated using Taguchi's concept to minimize the observations needed, and ANOVA was used to identify interactions between tested parameters and to identify the most significant parameters. The S/N ratio indicates that there is only percentage of deviation between the predicted and experimental results. In further, sophisticated analyses and GMDH methods were employed, and surface damage was examined using scanning electron microscopy (SEM) to examine the nature of the wear behaviour.

  11. Effects of Surface Treatments on Mechanical Properties and Water Resistance of Kenaf Fiber-Reinforced Unsaturated Polyester Composites

    SciTech Connect

    Ren, Xiaofeng; Qui, Renhui; Fifield, Leonard S.; Simmons, Kevin L.; li, Kaichang

    2012-05-17

    Effects of surface treatments on the strength and water resistance of kenaf fiber-reinforced unsaturated polyester (UPE) composites were investigated. A new coupling agent that consists of 1,6-diisocyanato-hexane (DIH) and 2-hydroxylethyl acrylate (HEA) was investigated for surface treatments of kenaf fibers. The surface treatments were found to significantly enhance the tensile strength, modulus of rupture, modulus of elasticity, and water resistance of the resulting kenaf UPE composites. Fourier transform infrared spectroscopy (FTIR) confirmed that DIH-HEA was covalently bonded onto kenaf fibers. Scanning electron microscopy (SEM) images of the composites revealed that chemical treatment of kenaf fibers with a combination of DIH and HEA improved the interfacial adhesion between kenaf fibers and UPE resin in the DIHHEA-treated kenafUPE composites. The mechanisms by which the chemical treatment of kenaf fiber surfaces improved strength and water resistance of the resulting kenaf UPE composites were discussed.

  12. Tensile properties and translaminar fracture toughness of glass fiber reinforced unsaturated polyester resin composites aged in distilled and salt water

    NASA Astrophysics Data System (ADS)

    Sugiman, Gozali, M. Hulaifi; Setyawan, Paryanto Dwi

    2016-03-01

    Glass fiber reinforced polymer has been widely used in chemical industry and transportation due to lightweight and cost effective manufacturing. However due to the ability to absorb water from the environment, the durability issue is of interest for up to days. This paper investigated the water uptake and the effect of absorbed water on the tensile properties and the translaminar fracture toughness of glass fiber reinforced unsaturated polyester composites (GFRP) aged in distilled and salt water up to 30 days at a temperature of 50°C. It has been shown that GFRP absorbed more water in distilled water than in salt water. In distilled water, the tensile strength of GFRP tends to decrease steeply at 7 days and then slightly recovered for further immersion time. In salt water, the tensile strength tends to decrease continually up to 30 days immersion. The translaminar fracture toughness of GFRP aged in both distilled and salt-water shows the similar behavior. The translaminar fracture toughness increases after 7 days immersion and then tends to decrease beyond that immersion time. In the existence of ionics content in salt water, it causes more detrimental effect on the mechanical properties of fiberglass/unsaturated polyester composites compared to that of distilled water.

  13. Depolymerization of unsaturated polyesters and waste fiber-reinforced plastics by using ionic liquids: the use of microwaves to accelerate the reaction rate.

    PubMed

    Kamimura, Akio; Yamamoto, Shigehiro; Yamada, Kazuo

    2011-05-23

    Waste fiber-reinforced plastics (FRP) and unsaturated polyesters were readily depolymerized by subjecting them to a treatment with ionic liquids under heating conditions. The use of microwaves for heating effectively progressed depolymerization, whereas the conventional heating method was ineffective for this purpose. We isolated the monomeric material, phthalic anhydride, by direct distillation from the reaction pot under reduced pressure with yields of more than 90%. We recovered the glass fibers in a pure form and achieved the effective removal of polystyrene, the linker unit of FRP. Ionic liquids were useful for several iterations of the reaction, and purification of the used ionic liquids was also possible. Thus, we developed a new use of ionic liquids for chemical recycling of waste plastics.

  14. Influence of wool and thermo-binder fibers relative fractions on the adhesion of non-woven Alfa fibers reinforced unsaturated polyester hybrid composites

    NASA Astrophysics Data System (ADS)

    Amin Omri, Med; Triki, A.; Ben Hassen, Med; Arous, M.; Bulou, A.

    2016-10-01

    Alfa/wool/thermo-binder fibers hybrid composites were investigated in order to analyze adhesion state. Bearing in mind the chemical structure of wool and thermo-binder fibers, this study revealed a good compatibility between the reinforcement and the matrix. Dielectric measurements revealed the presence of two dielectric relaxations in the composite. The first relaxation was attributed to the α mode relaxation and the second one was associated with the conductivity noted for high temperature. This study allowed the analysis of the interfacial polarization effect using the Havrilliak-Negami model in the electric modulus formalism. The lowness of this relaxation intensity revealed a good adhesion of the fibers in the matrix. Differential Scanning Calorimetry (DSC) showed a slow decrease of the Tg glass transition temperature compared to the matrix, which could be explained by the existence of interactions between the fibers and the matrix. Vibrational analysis, based on FTIR measurements, showed a less hydrophilic character of Alfa fibers owing to a basic dissociation that occurs between the wool fibers and the water molecules associated with Alfa fibers. Furthermore, adhesion mechanism in the composite material was established by covalent and hydrogen bonds. Tensile testing performed on this composite confirmed that such adhesion was improved by increasing the thermo-binder fibers relative fraction.

  15. 77 FR 60720 - Certain Polyester Staple Fiber From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-04

    ... COMMISSION Certain Polyester Staple Fiber From China Determination On the basis of the record \\1\\ developed... antidumping duty order on certain polyester staple fiber from China would be likely to lead to continuation or... USITC Publication 4351 (September 2012), entitled Certain Polyester Staple Fiber from...

  16. Rheological behaviour of nanocellulose reinforced unsaturated polyester nanocomposites.

    PubMed

    Chirayil, Cintil Jose; Mathew, Lovely; Hassan, P A; Mozetic, Miran; Thomas, Sabu

    2014-08-01

    Nanocellulose (NC) reinforced unsaturated polyester (UPR) composites were prepared by mechanical mixing process. Effect of isora nanocellulose on the properties of polyester composites has been studied in detail. Rheological properties of unsaturated polyester resin suspensions containing various amounts (0.5, 1 and 3wt%) of nanocellulose were investigated by oscillatory rheometer with parallel plate geometry. Analysis of curing revealed that the time required for gelation in NC filled UPR is lower than neat resin, which describe the catalytic action of NC on cure reaction. NC reinforced polyester suspensions showed shear thinning behaviour initially and at higher shear rates they showed Newtonian behaviour. Tensile and impact properties showed superior behaviour revealing improved interfacial bonding between nanofiller and the polymer matrix. With respect to the neat polyester the percentage increase in tensile strength of 0.5wt% NC reinforced composite is 57%. Optical and atomic force microscopic studies confirmed that the dispersion state of NC within the polyester matrix was adequate. Maximum glass transition temperature is obtained for 0.5wt% NC reinforced composite, which showed an increase of 10°C than neat resin.

  17. 76 FR 57955 - Certain Polyester Staple Fiber From Taiwan: Final Results of Antidumping Duty Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-19

    ... International Trade Administration Certain Polyester Staple Fiber From Taiwan: Final Results of Antidumping Duty... administrative review of the antidumping duty order on certain polyester staple fiber from Taiwan. The period of... certain polyester staple fiber from Taiwan. See Certain Polyester Staple Fiber From Taiwan:...

  18. 78 FR 51707 - Certain Polyester Staple Fiber From the Republic of Korea: Rescission of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-21

    ... International Trade Administration Certain Polyester Staple Fiber From the Republic of Korea: Rescission of... administrative review of the antidumping duty order on certain polyester staple fiber (polyester staple fiber... antidumping duty order on polyester staple fiber from Korea for the period May 1, 2012, through April 30,...

  19. 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.

  20. 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.

  1. 78 FR 14512 - Certain Polyester Staple Fiber From the People's Republic of China: Preliminary Results and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ... International Trade Administration Certain Polyester Staple Fiber From the People's Republic of China... order on certain polyester staple fiber from the People's Republic of China (``PRC''). The period of... Sichuan Chemical Fiber Corp. and Huvis Sichuan Polyester Fiber Ltd. (``Huvis Sichuan'') are part of...

  2. Optimization on Impact Strength of Woven Kenaf Reinforced Polyester Composites using Taguchi Method

    NASA Astrophysics Data System (ADS)

    Khalid, S. N. A.; Ismail, A. E.; Zainulabidin, M. H.

    2017-01-01

    This paper focuses on the effect of weaving patterns and orientations on the energy absorption of woven kenaf reinforced polyester composites. Kenaf fiber in the form of yarn is weaved to produce different weaving patterns such as plain, twill and basket. Three woven mats are stacked together and mixed with polyester resin before it is compressed to squeeze out any excessive resin. There is nine different orientations are used during stacking processes by following Taguchi orthogonal arrays method. The hardened composites are cured for 24 hours before it is shaped according to specific dimensions for impact tests. The composites are perforated with 1m/s blunted projectile. According to the experimental findings, weaving pattern and orientation have distinct potential effects on value of energy absorption. The optimization using Taguchi method reveals preferable orientation of each weaving pattern composites. Based on the fracture observation, the fragmentations after optimization indicating lower distance surface fracture perforated obtained.

  3. 77 FR 54562 - Certain Polyester Staple Fiber From the Republic of Korea: Rescission of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-05

    ...] Certain Polyester Staple Fiber From the Republic of Korea: Rescission of Antidumping Duty Administrative...'') initiated an administrative review of the antidumping duty order on certain polyester staple fiber from...

  4. Mechanical behavior of glass fiber polyester hybrid composite filled with natural fillers

    NASA Astrophysics Data System (ADS)

    Gupta, G.; Gupta, A.; Dhanola, A.; Raturi, A.

    2016-09-01

    Now-a-days, the natural fibers and fillers from renewable natural resources offer the potential to act as a reinforcing material for polymer composite material alternative to the use of synthetic fiber like as; glass, carbon and other man-made fibers. Among various natural fibers and fillers like banana, wheat straw, rice husk, wood powder, sisal, jute, hemp etc. are the most widely used natural fibers and fillers due to its advantages like easy availability, low density, low production cost and reasonable physical and mechanical properties This research work presents the effect of natural fillers loading with 5%, 10% and 15% on mechanical behavior of polyester based hybrid composites. The result of test depicted that hybrid composite has far better properties than single fibre glass reinforced composite under impact and flexural loads. However it is found that the hybrid composite have better strength as compared to single glass fibre composites.

  5. 75 FR 30373 - Certain Polyester Staple Fiber From the People's Republic of China: Extension of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-01

    ... International Trade Administration Certain Polyester Staple Fiber From the People's Republic of China: Extension... polyester staple fiber from the People's Republic of China (``PRC''). This review covers the period June 1... polyester staple fiber from the PRC. See Initiation of Antidumping and Countervailing Duty...

  6. 77 FR 19619 - Certain Polyester Staple Fiber from the People's Republic of China: Extension of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-02

    ... International Trade Administration Certain Polyester Staple Fiber from the People's Republic of China: Extension... polyester staple fiber from the People's Republic of China (``PRC''). This review covers the period June 1... administrative review of the antidumping duty order on certain polyester staple fiber from the PRC.\\1\\...

  7. 75 FR 51442 - Polyester Staple Fiber from Taiwan: Rescission of Antidumping Duty Administrative Review in Part

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-20

    ... International Trade Administration Polyester Staple Fiber from Taiwan: Rescission of Antidumping Duty... Commerce initiated an administrative review of the antidumping duty order on polyester staple fiber from...) initiated an ] administrative review of the antidumping duty order on polyester staple fiber from...

  8. 78 FR 17637 - Polyester Staple Fiber From Taiwan: Preliminary Results of Antidumping Duty Administrative Review...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-22

    ... International Trade Administration Polyester Staple Fiber From Taiwan: Preliminary Results of Antidumping Duty... the antidumping duty order on polyester staple fiber (PSF) from Taiwan. The period of review (POR) is... Antidumping Duty Administrative Review: Polyester Staple Fiber from Taiwan'' dated concurrently with...

  9. 75 FR 43921 - Certain Polyester Staple Fiber From Taiwan: Final Results of Antidumping Duty Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-27

    ... International Trade Administration Certain Polyester Staple Fiber From Taiwan: Final Results of Antidumping Duty... administrative review of the antidumping duty order on certain polyester staple fiber from Taiwan. The period of... review of the antidumping duty order on certain polyester staple fiber (PSF) from Taiwan. See...

  10. 75 FR 6352 - Certain Polyester Staple Fiber from the People's Republic of China: Extension of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-09

    ... International Trade Administration Certain Polyester Staple Fiber from the People's Republic of China: Extension... polyester staple fiber from the People's Republic of China (``PRC''). This review covers the period June 1... duty order on certain polyester staple fiber from the PRC. See Initiation of Antidumping...

  11. 76 FR 7532 - Certain Polyester Staple Fiber From the People's Republic of China: Extension of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-10

    ... International Trade Administration Certain Polyester Staple Fiber From the People's Republic of China: Extension... polyester staple fiber from the People's Republic of China (``PRC''). This review covers the period June 1... duty order on certain polyester staple fiber from the PRC. See Initiation of Antidumping...

  12. 77 FR 54561 - Certain Polyester Staple Fiber From Taiwan: Final Results of Antidumping Duty Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-05

    ...] Certain Polyester Staple Fiber From Taiwan: Final Results of Antidumping Duty Administrative Review AGENCY... antidumping duty order on certain polyester staple fiber from Taiwan. The period of review is May 1, 2010... administrative review of the antidumping duty order on certain polyester staple fiber from Taiwan. See...

  13. 77 FR 6783 - Certain Polyester Staple Fiber From the People's Republic of China: Extension of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-09

    ... International Trade Administration Certain Polyester Staple Fiber From the People's Republic of China: Extension... polyester staple fiber from the People's Republic of China (``PRC''). This review covers the period June 1... administrative review of the antidumping duty order on certain polyester staple fiber from the PRC....

  14. 76 FR 58040 - Certain Polyester Staple Fiber From Korea and Taiwan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-19

    ... COMMISSION Certain Polyester Staple Fiber From Korea and Taiwan Determination On the basis of the record \\1... antidumping duty orders on certain polyester staple fiber from Korea and Taiwan would be likely to lead to...), entitled Certain Polyester Staple Fiber From Korea and Taiwan: Investigation Nos. 731-TA-825 and...

  15. 75 FR 39208 - Polyester Staple Fiber from Taiwan: Final Results of Changed-Circumstances Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-08

    ... International Trade Administration Polyester Staple Fiber from Taiwan: Final Results of Changed- Circumstances... antidumping duty order on polyester staple fiber from Taiwan. DATES: Effective Date: July 8, 2010. FOR FURTHER... changed-circumstances review of the antidumping duty order on polyester staple fiber from Taiwan...

  16. 77 FR 62217 - Certain Polyester Staple Fiber From the People's Republic of China: Continuation of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-12

    ... Polyester Staple Fiber From the People's Republic of China: Continuation of Antidumping Duty Order AGENCY... certain polyester staple fiber from the People's Republic of China (``PRC'') would likely lead to a... the sunset review of the antidumping duty order on certain polyester staple fiber from the...

  17. 78 FR 38938 - Polyester Staple Fiber From Taiwan: Final Results of Antidumping Duty Administrative Review; 2011...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-28

    ... International Trade Administration Polyester Staple Fiber From Taiwan: Final Results of Antidumping Duty... results of the administrative review of the antidumping duty order on polyester staple fiber (PSF) from... Preliminary Results. None were received. \\1\\ See Polyester Staple Fiber From Taiwan: Preliminary Results...

  18. 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.

  19. Impact Strength of Different Weaving Patterns of Woven Kenaf Reinforced Polyester Composites

    NASA Astrophysics Data System (ADS)

    Khalid, S. N. A.; Ismail, A. E.; Zainulabidin, M. H.

    2017-01-01

    This paper focuses on the effect of weaving patterns and orientations on the energy absorption of woven kenaf reinforced polyester composites. Kenaf fiber in the form of yarn is weaved to produce different weaving patterns such as plain, twill and basket. Three woven mats are stacked together and mixed with polyester resin before it is compressed to squeeze out any excessive resin. There is 9 different orientations are used during stacking processes. The hardened composites are cured for 24 hours before it is shaped according to specific dimensions for imp act tests. The composites are perforated with 1m/s blunted projectile. According to the experimental findings, both weaving patterns and orientations have distinct potential effects on the force-displacement diagrams. However, fiber orientations have insignificant effect for plain woven especially in the first stage of deformations. Energy absorption performances for each composite condition are calculated and then plotted against fiber orientations for different weaving patterns. It is found there is no strong relationship between energy absorption and fiber orientations. However for each case of composites, higher energy absorption is found for the composites orientated using [+40°/-15°/+40°/+75°]. Based on the fracture observation, both plain and basket-type woven composites reveal large fragmentations occurred indicating lower energy absorption performances. While for twill condition, no obvious fragmentation is observed where the impact damage around the perforated hole is uniformly distributed leading to higher capability of energy absorptions.

  20. Liquid crystal polyester-carbon fiber composites

    NASA Technical Reports Server (NTRS)

    Chung, T. S.

    1984-01-01

    Liquid crystal polymers (LCP) have been developed as a thermoplastic matrix for high performance composites. A successful melt impregnation method has been developed which results in the production of continuous carbon fiber (CF) reinforced LCP prepreg tape. Subsequent layup and molding of prepreg into laminates has yielded composites of good quality. Tensile and flexural properties of LCP/CF composites are comparable to those of epoxy/CF composites. The LCP/CF composites have better impact resistance than the latter, although epoxy/CF composites possess superior compression and shear strength. The LCP/CF composites have good property retention until 200 F (67 % of room temperature value). Above 200 F, mechanical properties decrease significantly. Experimental results indicate that the poor compression and shear strength may be due to the poor interfacial adhesion between the matrix and carbon fiber as adequate toughness of the LCP matrix. Low mechanical property retention at high temperatures may be attributable to the low beta-transition temperature (around 80 C) of the LCP matrix material.

  1. Fiber-reinforced syntactic foams

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Jen

    Long fibers are generally preferred for reinforcing foams for performance reasons. However, uniform dispersion is difficult to achieve because they must be mixed with liquid resin prior to foam expansion. New approaches aiming to overcome such problem have been developed at USC's Composites Center. Fiber-reinforced syntactic foams with long fibers (over 6 mm in length) manufactured at USC's Composites Center have achieved promising mechanical properties and demonstrated lower density relative to conventional composite foams. Fiber-reinforced syntactic foams were synthesized from thermosetting polymeric microspheres (amino and phenolic microspheres), as well as thermoplastic PVC heat expandable microspheres (HEMs). Carbon and/or aramid fibers were used to reinforce the syntactic foams. Basic mechanical properties, including shear, tensile, and compression, were measured in syntactic foams and fiber-reinforced syntactic foams. Microstructure and crack propagation behavior were investigated by scanning electron microscope and light microscopy. Failure mechanisms and reinforcing mechanisms of fiber-reinforced syntactic foams were also analyzed. As expected, additions of fiber reinforcements to foams enhanced both tensile and shear properties. However, only limited enhancement in compression properties was observed, and fiber reinforcement was of limited benefit in this regard. Therefore, a hybrid foam design was explored and evaluated in an attempt to enhance compression properties. HEMs were blended with glass microspheres to produce hybrid foams, and hybrid foams were subsequently reinforced with continuous aramid fibers to produce fiber-reinforced hybrid foams. Mechanical properties of these foams were evaluated. Findings indicated that the production of hybrid foams was an effective way to enhance the compressive properties of syntactic foams, while the addition of fiber reinforcements enhanced the shear and tensile performance of syntactic foams. Another approach

  2. 76 FR 22366 - Certain Polyester Staple Fiber From Taiwan: Preliminary Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-21

    ... International Trade Administration Certain Polyester Staple Fiber From Taiwan: Preliminary Results of... review of the antidumping duty order on certain polyester staple fiber (PSF) from Taiwan. The period of... 30, 2010). We have rescinded the review in part with respect to Nan Ya. See Polyester Staple...

  3. Glass fibres reinforced polyester composites degradation monitoring by surface analysis

    NASA Astrophysics Data System (ADS)

    Croitoru, Catalin; Patachia, Silvia; Papancea, Adina; Baltes, Liana; Tierean, Mircea

    2015-12-01

    The paper presents a novel method for quantification of the modifications that occur on the surface of different types of gel-coated glass fibre-reinforced polyester composites under artificial UV-ageing at 254 nm. The method implies the adsorption of an ionic dye, namely methylene blue, on the UV-aged composite, and computing the CIELab colour space parameters from the photographic image of the coloured composite's surface. The method significantly enhances the colour differences between the irradiated composites and the reference, in contrast with the non-coloured ones. The colour modifications that occur represent a good indicative of the surface degradation, alteration of surface hydrophily and roughness of the composite and are in good correlation with the ATR-FTIR spectroscopy and optical microscopy results. The proposed method is easier, faster and cheaper than the traditional ones.

  4. Fiber reinforced concrete solar collector

    SciTech Connect

    Slemmons, A. J.; Newgard, P. J.

    1985-05-07

    A solar collector is disclosed comprising a glass member having a solar selective coating thereon, and a molded, glass-reinforced concrete member bonded to the glass member and shaped to provide a series of passageways between the glass member and the fiber-reinforced concrete member capable of carrying heat exchanging fluid therethrough. The fiber-reinforced concrete member may be formed by spraying a thin layer of concrete and chopped fibers such as chopped glass fibers onto a mold to provide an inexpensive and lightweight, thin-walled member. The fiber-reinforced concrete member may have a lightweight cellular concrete backing thereon for insulation purposes. The collector is further characterized by the use of materials which have substantially matching thermal coefficients of expansion over the temperature range normally encountered in the use of solar collectors.

  5. 76 FR 52935 - Certain Polyester Staple Fiber From Korea: Rescission of Antidumping Duty Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-24

    ... International Trade Administration Certain Polyester Staple Fiber From Korea: Rescission of Antidumping Duty... to request an administrative review of the antidumping order on polyester staple fiber from Korea... staple fiber covered by the scope of the order is defined as synthetic staple fibers, not carded,...

  6. Viscoelastic properties of kenaf reinforced unsaturated polyester composites

    NASA Astrophysics Data System (ADS)

    Osman, Ekhlas A.; Mutasher, Saad A.

    2014-03-01

    In order to quantify the effect of temperature on the mechanical and dynamic properties of kenaf fiber unsaturated polyester composites, formulations containing 10 wt.% to 40 wt.% kenaf fiber were produced and tested at two representative temperatures of 30°C and 50°C. Dynamic mechanical analysis was performed, to obtain the strain and creep compliance for kenaf composites at various styrene concentrations. It is possible to obtain creep curves at different temperature levels which can be shifted along the time axis to generate a single curve known as a master curve. This technique is known as the time-temperature superposition principle. Shift factors conformed to a William-Landel-Ferry (WLF) equation. However, more long term creep data was needed in order to further validate the applicability of time-temperature superposition principle (TTSP) to this material. The primary creep strain model was fitted to 60 min creep data. The resulting equation was then extrapolated to 5.5 days; the creep strain model of power-law was successfully used to predict the long-term creep behavior of natural fiber/thermoset composites.

  7. Study on moisture absorption and sweat discharge of honeycomb polyester fiber

    NASA Astrophysics Data System (ADS)

    Feng, Aifen; Zhang, Yongjiu

    2015-07-01

    The moisture absorption and liberation properties of honeycomb polyester fiber were studied in order to understand its moisture absorption and sweat discharge. Through testing moisture absorption and liberation regains of honeycomb polyester fiber and normal polyester fiber in standard atmospheric conditions, their moisture absorption and liberation curves were depicted, and the regression equations of moisture regains to time during their reaching the balance of moisture absorption and moisture liberation were obtained according to the curves. Their moisture absorption and liberation rate curves were analyzed and the regression equations of the rates to time were obtained. The results shows that the moisture regain of honeycomb polyester fiber is much bigger than the normal polyester fiber's, and the initial moisture absorption and moisture liberation rates of the former are much higher than the latter's, so that the moisture absorbance and sweat discharge of honeycomb polyester fiber are excellent.

  8. Short-fiber-reinforced thermoplastics

    SciTech Connect

    Tekkanat, B.

    1987-01-01

    One of the objectives of this study was to explore the simplest predictive theories for composite stiffness and strength in injection-molded SFRTP materials which would be easy to use and would be accurate over a wide range of materials. The intention was also to try to understand the predicted dependence of stiffness and strength on fiber length for SFRTP's. The effects of matrix ductility on the mechanical properties and failure mechanisms of SFRTP's were investigated by controlling the matrix ductility via composition in PS-PPO system. In addition to matrix ductility, consideration was given to the following parameters: fiber-length distribution (FLD), fiber-orientation distribution (FOD), fiber-volume fraction, aspect ratio, and fiber-end configuration to understand the role they play on the mechanical properties, efficiency of reinforcement, and failure mechanisms of SFRTP's. Sub-surface analysis by transmission optical microscopy under polarized light was utilized along with fracture surface analysis and found to be a useful technique in determining the detailed microdeformation mechanisms of both matrix and short-fiber-reinforced systems. Fiber-reinforcement efficiency in terms of both stiffness and strength was found to be strongly dependent on the fiber length and fiber-volume fraction.

  9. 77 FR 25744 - Certain Polyester Staple Fiber From China; Institution of a Five-Year Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-01

    ... COMMISSION Certain Polyester Staple Fiber From China; Institution of a Five- Year Review AGENCY: United... fiber from China would be likely to lead to continuation or recurrence of material injury. Pursuant to... order on imports of certain polyester staple fiber from China (72 FR 30545). The Commission...

  10. 75 FR 5964 - Certain Polyester Staple Fiber From Taiwan: Preliminary Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-05

    ... International Trade Administration Certain Polyester Staple Fiber From Taiwan: Preliminary Results of... review of the antidumping duty order on certain polyester staple fiber (PSF) from Taiwan. The period of... fiber from one producer/exporter. We have preliminarily found that sales of the subject merchandise...

  11. 75 FR 64694 - Second Antidumping Duty Administrative Review of Certain Polyester Staple Fiber From the People's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-20

    ... Fiber From the People's Republic of China: Extension of Time Limit for the Final Results Agency: Import... the Preliminary Results of the second administrative review of certain polyester staple fiber (``PSF... Polyester Staple Fiber From the People's Republic of China: Notice of Preliminary Results and...

  12. 75 FR 47795 - Certain Polyester Staple Fiber from Korea: Rescission of Antidumping Duty Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-09

    ... International Trade Administration Certain Polyester Staple Fiber from Korea: Rescission of Antidumping Duty... (June 30, 2010). Scope of the Order Polyester staple fiber (``PSF'') covered by the scope of the order is defined as synthetic staple fibers, not carded, combed or otherwise processed for spinning,...

  13. 76 FR 11268 - Certain Polyester Staple Fiber From Korea and Taiwan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-01

    ... COMMISSION Certain Polyester Staple Fiber From Korea and Taiwan AGENCY: United States International Trade... staple fiber from Korea and Taiwan. SUMMARY: The Commission hereby gives notice that it has instituted... whether revocation of the antidumping duty orders on certain polyester staple fiber from Korea and...

  14. The research of far infrared flame retardant polyester staple fiber

    NASA Astrophysics Data System (ADS)

    Li, Qingshan; Zhang, Kaijun; Luo, Jinqong; Li, Ji’an; Jiang, Jian; Liang, Qianqian; Jin, Yongxia; Liu, Bing

    2017-01-01

    Far infrared flame retardant slices was prepared, fiber with far infrared flame retardant composite function was also prepared by the method of melt spinning. Scanning electron microscopy (SEM) was used to observe the fibrous microscopic structure. In the SEM images, functional ultrafine powder particle size and distribution in the fiber were visible. The results show that the functional ultrafine powder is evenly distributed on the fibrous surface, which is closely combined with fiber, and the far infrared emissivity is F, which is more than (8 to 14 microns) 0.88. Far infrared flame retardant polyester fiber has not only good flame retardant, but also environmental health effect: releasing negative ions and launch far-infrared, which shows wide application prospect. The fiber was processed into far-infrared flame retardant electric blanket, whose functional indicators and flame retardant properties are not reduced.

  15. GLASS FIBER REINFORCED PLASTICS,

    DTIC Science & Technology

    Contents: Fibrous glass fillers Binders used in the glass plastic industry Method of manufacturing glass plastics and glass plastic articles Properties of fiberglass Primary areas for use of glass fibre reinforced plastics

  16. 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.

  17. 77 FR 50530 - Polyester Staple Fiber From China; Scheduling of an Expedited Five-Year Review Concerning the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-21

    ... COMMISSION Polyester Staple Fiber From China; Scheduling of an Expedited Five-Year Review Concerning the Antidumping Duty Order on Polyester Staple Fiber From China AGENCY: United States International Trade... determine ] whether revocation of the antidumping duty order on polyester staple fiber from China would...

  18. 76 FR 28420 - Certain Polyester Staple Fiber From the People's Republic of China: Full Extension of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-17

    ... International Trade Administration Certain Polyester Staple Fiber From the People's Republic of China: Full... polyester staple fiber from the People's Republic of China (``PRC''). This review covers the period June 1... duty order on certain polyester staple fiber from the PRC. See Initiation of Antidumping...

  19. 78 FR 38939 - Certain Polyester Staple Fiber From the People's Republic of China: Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-28

    ... International Trade Administration Certain Polyester Staple Fiber From the People's Republic of China: Final... antidumping duty order on certain polyester staple fiber (``PSF'') from the People's Republic of China (``PRC... below. \\1\\ See Certain Polyester Staple Fiber From the People's Republic of China: Preliminary...

  20. 75 FR 1336 - First Administrative Review of Certain Polyester Staple Fiber From the People's Republic of China...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-11

    ... International Trade Administration First Administrative Review of Certain Polyester Staple Fiber From the People... first administrative review of the antidumping duty order on certain polyester staple fiber (``PSF'') from the People's Republic of China (``PRC''). See Certain Polyester Staple Fiber from the...

  1. 76 FR 2886 - Certain Polyester Staple Fiber From the People's Republic of China: Final Results and Partial...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-18

    ... International Trade Administration Certain Polyester Staple Fiber From the People's Republic of China: Final... second administrative review of the antidumping duty order on certain polyester staple fiber (``PSF'') from the People's Republic of China (``PRC''). See Certain Polyester Staple Fiber From the...

  2. 75 FR 76954 - Certain Polyester Staple Fiber From the People's Republic of China: Extension of Time Limit for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-10

    ... International Trade Administration Certain Polyester Staple Fiber From the People's Republic of China: Extension... Register the Preliminary Results of the second administrative review of certain polyester staple fiber.... See Certain Polyester Staple Fiber From the People's Republic of China: Notice of Preliminary...

  3. 76 FR 60802 - Certain Polyester Staple Fiber From the Republic of Korea and Taiwan: Continuation of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-30

    ... International Trade Administration Certain Polyester Staple Fiber From the Republic of Korea and Taiwan... certain polyester staple fiber from the Republic of Korea (Korea) and Taiwan would likely lead to a... orders on polyester staple fiber from Korea and Taiwan \\1\\ pursuant to section 751(c) of the Tariff...

  4. 77 FR 71579 - Polyester Staple Fiber From Taiwan: Notice of Court Decision Not in Harmony With Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-03

    ... International Trade Administration Polyester Staple Fiber From Taiwan: Notice of Court Decision Not in Harmony... order on polyester staple fiber from Taiwan covering the period of review (``POR'') May 1, 2009, through... Certain Polyester Staple Fiber From Taiwan: Final Results of Antidumping Duty Administrative Review, 76...

  5. 76 FR 37830 - Polyester Staple Fiber From Korea and Taiwan; Scheduling of Expedited Five-Year Reviews...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-28

    ... COMMISSION Polyester Staple Fiber From Korea and Taiwan; Scheduling of Expedited Five-Year Reviews Concerning the Antidumping Duty Orders on Polyester Staple Fiber From Korea and Taiwan AGENCY: United States...) to determine whether revocation of the antidumping duty orders on polyester staple fiber from...

  6. 75 FR 34097 - Certain Polyester Staple Fiber From Taiwan: Extension of the Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-16

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Certain Polyester Staple Fiber From Taiwan: Extension of the Final Results of... certain polyester staple fiber from Taiwan. See Certain Polyester Staple Fiber from Taiwan:...

  7. The assessment of metal fiber reinforced polymeric composites

    NASA Technical Reports Server (NTRS)

    Chung, Wenchiang R.

    1990-01-01

    Because of their low cost, excellent electrical conductivity, high specific strength (strength/density), and high specific modulus (modulus/density) short metal fiber reinforced composites have enjoyed a widespread use in many critical applications such as automotive industry, aircraft manufacturing, national defense, and space technology. However, little data has been found in the study of short metal fibrous composites. Optimum fiber concentration in a resin matrix and fiber aspect ratio (length-to-diameter ratio) are often not available to a user. Stress concentration at short fiber ends is the other concern when the composite is applied to a load-bearing application. Fracture in such composites where the damage will be initiated or accumulated is usually difficult to be determined. An experimental investigation is therefore carefully designed and undertaken to systematically evaluate the mechanical properties as well as electrical properties. Inconel 601 (nickel based) metal fiber with a diameter of eight microns is used to reinforce commercially available thermoset polyester resin. Mechanical testing such as tensile, impact, and flexure tests along with electrical conductivity measurements is conducted to study the feasibility of using such composites. The advantages and limitations of applying chopped metal fiber reinforced polymeric composites are also discussed.

  8. Natural Curaua Fiber-Reinforced Composites in Multilayered Ballistic Armor

    NASA Astrophysics Data System (ADS)

    Monteiro, Sergio Neves; Louro, Luis Henrique Leme; Trindade, Willian; Elias, Carlos Nelson; Ferreira, Carlos Luiz; de Sousa Lima, Eduardo; Weber, Ricardo Pondé; Miguez Suarez, João Carlos; da Silva Figueiredo, André Ben-Hur; Pinheiro, Wagner Anacleto; da Silva, Luis Carlos; Lima, Édio Pereira

    2015-10-01

    The performance of a novel multilayered armor in which the commonly used plies of aramid fabric layer were replaced by an equal thickness layer of distinct curaua fiber-reinforced composites with epoxy or polyester matrices was assessed. The investigated armor, in addition to its polymeric layer (aramid fabric or curaua composite), was also composed of a front Al2O3 ceramic tile and backed by an aluminum alloy sheet. Ballistic impact tests were performed with actual 7.62 caliber ammunitions. Indentation in a clay witness, simulating human body behind the back layer, attested the efficacy of the curaua-reinforced composite as an armor component. The conventional aramid fabric display a similar indentation as the curaua/polyester composite but was less efficient (deeper indentation) than the curaua/epoxy composite. This advantage is shown to be significant, especially in favor of the lighter and cheaper epoxy composite reinforced with 30 vol pct of curaua fiber, as possible substitute for aramid fabric in multilayered ballistic armor for individual protection. Scanning electron microscopy revealed the mechanism associated with the curaua composite ballistic performance.

  9. 75 FR 64252 - Certain Polyester Staple Fiber From the Republic of Korea: Final Results of the 2008-2009...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-19

    ... International Trade Administration Certain Polyester Staple Fiber From the Republic of Korea: Final Results of... certain polyester staple fiber from the Republic of Korea and invited interested parties to comment. The... 15, 2010, the Department of Commerce (``the Department'') published Certain Polyester Staple...

  10. Toughness of fiber reinforced shotcrete

    SciTech Connect

    Morgan, D.R.; Chen, L.; Beaupre, D.

    1995-12-31

    Fibers are added to shotcrete to improve energy absorption and impact resistance, to provide crack resistance and crack control, and to provide apparent ductility, i.e., an ability to continue to carry load after the shotcrete matrix has cracked. In order to be able to quantify the benefits of fiber addition, a variety of different toughness measuring systems have been developed in different countries. Most commonly used are flexural toughness systems which determine load vs. deflection responses and relate the area under the curve to some absolute or dimensionless index energy parameter. In North America the ASTM C1018 test method is most commonly used. In Japan the JSCE-SF4 test procedure is used. A variety of procedures have been used in Europe, but the template approach of the Norwegian Guidelines NBP No. 7, seems to be finding favor. This paper briefly assesses the relative advantages and disadvantages of the various methods of characterizing toughness. It then provides recommendations for a new procedure which uses the ASTM C1018 test method for generating the flexural load vs. deflection curve, but analyzes the data using a modified version of the Norwegian template approach. The load vs. deflection curve is directly compared against four residual strength curves and the fiber reinforced shotcrete assigned one of four toughness performance levels. It is believed that this new procedure should provide suitable within and between laboratory reproducibility and be more suitable for purposes of differentiating between different fiber types and addition rates and specifying toughness for fiber reinforced shotcrete products than any of the existing methods.

  11. Fiber reinforced composite resin systems.

    PubMed

    Giordano, R

    2000-01-01

    The Targis/Vectris and Sculpture/FibreKor systems were devised to create a translucent maximally reinforced resin framework for fabrication of crowns, bridges, inlays, and onlays. These materials are esthetic, have translucency similar to castable glass-ceramics such as OPC and Empress, and have fits that are reported to be acceptable in clinical and laboratory trials. These restorations rely on proper bonding to the remaining tooth structure; therefore, careful attention to detail must be paid to this part of the procedure. Cementation procedures should involve silane treatment of the cleaned abraded internal restoration surface, application of bonding agent to the restoration as well as the etched/primed tooth, and finally use of a composite resin. Each manufacturer has a recommended system which has been tested for success with its resin system. These fiber reinforced resins are somewhat different than classical composites, so not all cementation systems will necessarily work with them. Polishing of the restoration can be accomplished using diamond or alumina impregnated rubber wheels followed by diamond paste. The glass fibers can pose a health risk. They are small enough to be inhaled and deposited in the lungs, resulting in a silicosis-type problem. Therefore, if fibers are exposed and ground on, it is extremely important to wear a mask. Also, the fibers can be a skin irritant, so gloves also should be worn. If the fibers become exposed intraorally, they can cause gingival inflammation and may attract plaque. The fibers should be covered with additional composite resin. If this cannot be accomplished, the restoration should be replaced. The bulk of these restorations are formed using a particulate filled resin, similar in structure to conventional composite resins. Therefore, concerns as to wear resistance, color stability, excessive expansion/contraction, and sensitivity remain until these materials are proven in long-term clinical trials. They do hold the

  12. FIBER-REINFORCED METALLIC COMPOSITE MATERIALS.

    DTIC Science & Technology

    COMPOSITE MATERIALS), (*FIBER METALLURGY, TITANIUM ALLOYS , NICKEL ALLOYS , REINFORCING MATERIALS, TUNGSTEN, WIRE, MOLYBDENUM ALLOYS , COBALT ALLOYS , CHROMIUM ALLOYS , ALUMINUM ALLOYS , MECHANICAL PROPERTIES, POWDER METALLURGY.

  13. 75 FR 70906 - Certain Polyester Staple Fiber From the People's Republic of China: Partial Rescission of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-19

    ... International Trade Administration Certain Polyester Staple Fiber From the People's Republic of China: Partial... certain polyester staple fiber (``PSF'') from the People's Republic of China (``PRC'') for the period of... from Ningbo Dafa Chemical Fiber Co., Ltd. (``Ningbo Dafa'') and Cixi Santai Chemical Fiber Co.,...

  14. 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.

  15. Machining fiber-reinforced composites

    NASA Astrophysics Data System (ADS)

    Komanduri, Ranga

    1993-04-01

    Compared to high tool wear and high costs of tooling of fiber-reinforced composites (FRCs), noncontact material-removal processes offer attractive alternative. Noncontact machining methods can also minimize dust, noise, and extensive plastic deformation and consequent heat generation associated with conventional machining of FRCs, espacially those with an epoxy matrix. The paper describes the principles involved in and the details of machining of FRCs by laser machining, water jet-cutting and abrasive water jet-cutting, and electrical discharge machining of composites, as well as the limitations of each method.

  16. Mechanical performance of hybrid polyester composites reinforced Cloisite 30B and kenaf fibre

    NASA Astrophysics Data System (ADS)

    Bonnia, N. N.; Surip, S. N.; Ratim, S.; Mahat, M. M.

    2012-06-01

    Hybridization of rubber toughened polyester-kenaf nanocomposite was prepared by adding various percentage of kenaf fiber with 4% Cloisite 30B in unsaturated polyester resin. Composite were prepared by adding filler to modified polyester resin subsequently cross-linked using methyl ethyl ketone peroxide and the accelerator cobalt octanoate 1%. Three per hundred rubbers (phr) of liquid natural rubber (LNR) were added in producing this composite. This composite expected to be applied in the interior of passenger cars and truck cabins. This is a quality local product from a combination of good properties polyester and high performance natural fiber, kenaf that is suitable for many applications such as in automotive sector and construction sector. The mechanical and thermal properties of composite were characterized using Durometer Shore-D hardness test, Izod impact test, Scanning electron microscopy, thermogravimetry (TGA) and differential scanning calorimetry (DSC). Result shows that addition of LNR give good properties on impact, flexural and hardness compare to without LNR composite. DSC curve shows that all composition of composites is fully cured and good in thermal properties. Addition of higher percentage of kenaf will lead the composite to elastic behavior and decrease the toughened properties of the composite. Hybrid system composite showed the flexural properties within the flexural properties of kenaf - polyester and Cloisite 30B.

  17. Microstructural characterization of fiber-reinforced composites

    SciTech Connect

    Summerscales, J.

    1998-12-31

    In the past 50 years, great progress has been made in developing artificial fiber-reinforced composite materials, generally using filaments with microscopic diameters. An array of reinforcement forms can be used in commercial applications--with the microstructure being a critical factor in realizing the required properties in a material. This book comprehensively examines the application of advanced microstructural characterization techniques to fiber-reinforced composites. Its contents include: (1) flexible textile composite microstructure; (2) 3-D confocal microscopy of glass fiber-reinforced composites; (3) geometric modeling of yarn and fiber assemblies; (4) characterization of yarn shape in woven fabric composites; (5) quantitative microstructural analysis for continuous fiber composites; (6) electron microscopy of polymer composites; (7) micromechanics of reinforcement using laser raman spectroscopy; and (8) acoustic microscopy of ceramic fiber composites.

  18. Morphological and biodegradability studies of Euphorbia latex modified polyester - Banana fiber composites

    NASA Astrophysics Data System (ADS)

    Rai, Bhuvneshwar; Kumar, Gulshan; Diwan, R. K.

    2016-05-01

    The composites of Banana fiber were prepared using polyester resin blended Euphorbia coagulum, morphology and the degree of rate of aerobic biodegradation of the prepared composites were studied. Polyester resin blended Euphorbia coagulum containing Banana fiber, Euphorbia coagulum and polyester resin taken in the ratio 40: 24: 36 was used for the study, which was the optimum composition of the composite reported in a previous study by the authors. In the biodegradability study cellulose has been used as positive reference material. Result shows that Euphorbia coagulum modified polyester - Banana fiber composites exhibited biodegradation to the extent of around 40%. The use of developed green composites may help in reducing the generation of non-biodegradable polymeric wastes.

  19. 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.

  20. 75 FR 5763 - Notice of Correction to the First Administrative Review of Certain Polyester Staple Fiber From...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-04

    ... Staple Fiber From the People's Republic of China: Final Results of Antidumping Duty Administrative Review... antidumping duty order on certain polyester staple fiber from the People's Republic of China (``PRC''). See First Administrative Review of Certain Polyester Staple Fiber From the People's Republic of China:...

  1. 76 FR 69702 - Certain Polyester Staple Fiber From the People's Republic of China: Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-09

    ... International Trade Administration Certain Polyester Staple Fiber From the People's Republic of China: Final...- 2010 administrative review of the antidumping duty order on certain polyester staple fiber from the... Results. We find that the mandatory respondents in this review, Ningbo Dafa Chemical Fiber Co.,...

  2. 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.

  3. Long-short fiber reinforced thermoplastics

    SciTech Connect

    Gore, C.R.; Cuff, G.; Cianelli, D.A.; Travis, J.E.

    1986-01-01

    This paper presents information on a new family of fiber-reinforced thermoplastic compounds developed by ICI PLC and now produced by LNP under the trade mark ''Verton.'' Production is by a pultrusion process, rather than by the usual compounding extruder, which enables a high level of impregnation to be achieved without damaging the fibers. The result in molded parts is a 0.24-0.40 inch (6-10 mm) typical fiber length versus 0.008-0.016 inches (0.2-0.4 mm) for conventional short fiber products. Consequently, this enables fabricators to achieve typically a 10 to 20-fold increase in average fiber length in the finished component. These long-short fiber reinforced compounds exhibit substantial property improvements over short fiber system. Processing conditions are similar to corresponding short fiber compounds.

  4. 77 FR 4543 - Certain Polyester Staple Fiber From Taiwan: Extension of Time Limit for Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-30

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Certain Polyester Staple Fiber From Taiwan: Extension of Time Limit for... antidumping duty order on certain polyester staple fiber from Taiwan for the period May 1, 2010, through...

  5. An overview of long fiber reinforced thermoplastics

    SciTech Connect

    Bockstedt, R.J.; Skarlupka, R.J.

    1995-12-01

    Long fiber reinforced thermoplastics (LFRTP) are a class of injection molding materials that extend the physical property envelope of thermoplastics polymers. These materials are manufactured by pulling continuous fiber tows through a thermoplastic polymer melt in a specialized processing die. The strands are subsequently cooled and chopped into pellets of equal length. LFRTP materials are available in virtually every common thermoplastic resin with glass, aramid, stainless steel, or carbon fiber reinforcement at levels up to 60% by weight. Unlike short fiber reinforced thermoplastics manufactured by conventional screw compounding processes, LFRTP exhibit simultaneous improvements in both flexural modulus and impact resistance. Improvements in load transfer, creep resistance at elevated temperatures, and dimensional stability can also be attributed to the long fiber network formed in the molded part. This unique combination of properties makes LFRTP the material of choice for replacement of metal structural assemblies in many automotive, industrial, consumer and recreational applications.

  6. Fracture Toughness of Fiber Reinforced Concrete.

    DTIC Science & Technology

    1983-06-01

    14, 1979, pp. 443-449. 5 Mindess , S., Lawrence, F. V., and Kesler, C. E., "The J-Integral as a Fracture Criterion for Fiber Reinforced Concrete...34 Cement and Con- crete Research, Vol. 7, 1977 , pp. 731-742. 6 Velazco, G., Visalvanich, K., and Shah, S. P., "Fracture Behavior and Analysis of Fiber

  7. On the suitability of fiberglass reinforced polyester as building material for mesocosms.

    PubMed

    Berghahn, R; Brandsch, J; Piringer, O; Pluta, H J; Winkler, T

    1999-07-01

    Gel- and topcoat surface layers on fiberglass [glass-reinforced plastic (GRP)] made of unsaturated resin based on isophthalic acid polyester and neopentyl glycol (ISO-NPG) were tested for leaching, ecotoxicity of water eluates, and abrasion by river sediments at a current speed of 0.5 m * s-1. Leaching from topcoat tempered at low temperature was significant, whereas it was negligible from highly tempered gelcoat. Water eluates from both gel-and topcoat were nontoxic in routinely employed biotests (bacteria, algae, daphnids). No abrasion by river sediments was detectable. Based on these results, GRP with gelcoat made of ISO-NPG is considered a suitable building material for mesocosms.

  8. POLYESTER GLASS PLASTICS FOR SHIPBUILDING,

    DTIC Science & Technology

    POLYESTER PLASTICS , SHIP HULLS), (*SHIP HULLS, POLYESTER PLASTICS ), GLASS TEXTILES, REINFORCING MATERIALS, SHIP STRUCTURAL COMPONENTS, COMPOSITE MATERIALS, PROCESSING, CHEMISTRY, HANDBOOKS, BINDERS, USSR

  9. Mechanical characterization and structural analysis of recycled fiber-reinforced-polymer resin-transfer-molded beams

    NASA Astrophysics Data System (ADS)

    Tan, Eugene Wie Loon

    1999-09-01

    The present investigation was focussed on the mechanical characterization and structural analysis of resin-transfer-molded beams containing recycled fiber-reinforced polymers. The beams were structurally reinforced with continuous unidirectional glass fibers. The reinforcing filler materials consisted entirely of recycled fiber-reinforced polymer wastes (trim and overspray). The principal resin was a 100-percent dicyclo-pentadiene unsaturated polyester specially formulated with very low viscosity for resin transfer molding. Variations of the resin transfer molding technique were employed to produce specimens for material characterization. The basic materials that constituted the structural beams, continuous-glass-fiber-reinforced, recycled-trim-filled and recycled-overspray-filled unsaturated polyesters, were fully characterized in axial and transverse compression and tension, and inplane and interlaminar shear, to ascertain their strengths, ultimate strains, elastic moduli and Poisson's ratios. Experimentally determined mechanical properties of the recycled-trim-filled and recycled-overspray-filled materials from the present investigation were superior to those of unsaturated polyester polymer concretes and Portland cement concretes. Mechanical testing and finite element analyses of flexure (1 x 1 x 20 in) and beam (2 x 4 x 40 in) specimens were conducted. These structurally-reinforced specimens were tested and analyzed in four-point, third-point flexure to determine their ultimate loads, maximum fiber stresses and mid-span deflections. The experimentally determined load capacities of these specimens were compared to those of equivalent steel-reinforced Portland cement concrete beams computed using reinforced concrete theory. Mechanics of materials beam theory was utilized to predict the ultimate loads and mid-span deflections of the flexure and beam specimens. However, these predictions proved to be severely inadequate. Finite element (fracture propagation

  10. 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.

  11. 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.

  12. Nano polypeptide particles reinforced polymer composite fibers.

    PubMed

    Li, Jiashen; Li, Yi; Zhang, Jing; Li, Gang; Liu, Xuan; Li, Zhi; Liu, Xuqing; Han, Yanxia; Zhao, Zheng

    2015-02-25

    Because of the intensified competition of land resources for growing food and natural textile fibers, there is an urgent need to reuse and recycle the consumed/wasted natural fibers as regenerated green materials. Although polypeptide was extracted from wool by alkaline hydrolysis, the size of the polypeptide fragments could be reduced to nanoscale. The wool polypeptide particles were fragile and could be crushed down to nano size again and dispersed evenly among polymer matrix under melt extrusion condition. The nano polypeptide particles could reinforce antiultraviolet capability, moisture regain, and mechanical properties of the polymer-polypeptide composite fibers.

  13. Characteristics of Coaxial Dielectric Barrier Discharge at an Atmospheric Pressure with a Swirling Gas Argon/Oxygen Mixture for the Surface Modification of Polyester Fiber Cord

    NASA Astrophysics Data System (ADS)

    Xu, Jinzhou; Zhong, Ping; Li, Jialing; Lin, Jie; Diao, Ying; Zhang, Jing

    2010-10-01

    A newly developed coaxial dielectric barrier discharge reactor with a length of 1000 mm at an atmospheric pressure was used for plasma treatment of polyester fiber cord in a roll-to-roll manner. In this reactor, swirling mixture gases of oxygen of about 1% and argon with a flow rate of 1.5 L/min to 2.7 L/min ensured the gas usage sparing, discharge uniformity and efficient fiber surface modification. The water contact angle and surface morphology of the treated fiber were measured. The results show that the surface oxygenation is mainly responsible for the wettability improvement of the fiber cord when passing through the plasma zone at a linear speed of 3 m/min to 8 m/min. The specimens of modified-polyester fiber reinforced rubber composite were also prepared for the interfacial shear strength tests. Furthermore, the effect of adding oxygen into argon discharge on the fiber surface oxidation was correlated with optical emission spectroscopy. Finally, the effect of adding oxygen into argon discharge on the kinetic processes of the active species generation were also analyzed.

  14. Biocomposites Prepared from Fiber Processing Wastes and Glycerol Polyesters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biocomposites were prepared by the addition of flax fiber processing waste to glycerol and adipic acid mixtures. The processing waste consisted of fiber, cuticle, and shive fragments generated during the commercial cleaning of retted flax bast fibers. These waste materials were added at 1, 3, or 5 w...

  15. FIBER LENGTH DISTRIBUTION MEASUREMENT FOR LONG GLASS AND CARBON FIBER REINFORCED INJECTION MOLDED THERMOPLASTICS

    SciTech Connect

    Kunc, Vlastimil; Frame, Barbara J; Nguyen, Ba N.; TuckerIII, Charles L.; Velez-Garcia, Gregorio

    2007-01-01

    Procedures for fiber length distribution (FLD) measurement of long fiber reinforced injection molded thermoplastics were refined for glass and carbon fibers. Techniques for sample selection, fiber separation, digitization and length measurement for both fiber types are described in detail. Quantitative FLD results are provided for glass and carbon reinforced polypropylene samples molded with a nominal original fiber length of 12.7 mm (1/2 in.) using equipment optimized for molding short fiber reinforced thermoplastics.

  16. Fiber glass reinforced structural materials for aerospace application

    NASA Technical Reports Server (NTRS)

    Bartlett, D. H.

    1968-01-01

    Evaluation of fiber glass reinforced plastic materials concludes that fiber glass construction is lighter than aluminum alloy construction. Low thermal conductivity and strength makes the fiber glass material useful in cryogenic tank supports.

  17. Fiber reinforcement of investment cast parts

    SciTech Connect

    Nolte, M.; Neussl, E.; Schaedlich-Stubenrauch, J.; Sahm, P.R.

    1993-12-31

    For 3 years now the Foundry-Institute (Giesserei-Institut) of the Aachen Institute of Technology has worked on the development of a new, low-cost production process for longfiber-reinforced light alloy components. The process baseline is oriented on the precision casting process in its investment casting mode, also known as lost wax process. The investment casting process is well known as a typical near-net-shape process for the manufacture of high-quality cast components, predominantly for applications in the aerospace industry (structured components, turbine blades and parts etc.) and enjoys significant growth rates during the last decades. After preliminary studies on the modification of single process substeps R & D work concentrated on the final-shape production of Al-components (Al-alloys A356, A357, 201 etc.) reinforced with long ceramic fibers. Both SiC and Al{sub 2}O{sub 3}-based fibers of several producers were used. Main interest focuses on techniques for a selective reinforcement of main stress sections. Without using conventional sintered preforms the fibers are infiltrated with molten metal under a support pressure of less than 1 MPa. Combined with a new developed wax pattern technique test specimens with a nearly homogeneous fiber distribution were produced. In addition, even reactive matrix alloys did not lead to destructive interface reactions. In most cases sufficient bonding between fibers and matrix could be observed. Following to these positive tendencies a considerable improvement of mechanical properties could be measured for longfiber reinforced Al-alloys. Both tensile strength and elastic modulus could be increased up to 100% compared with the unreinforced matrix alloy. Latest work concentrated on the production of small representative components for potential applications.

  18. 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.

  19. CO2-Laser Cutting Fiber Reinforced Polymers

    NASA Astrophysics Data System (ADS)

    Mueller, R.; Nuss, Rudolf; Geiger, Manfred

    1989-10-01

    Guided by experimental investigations laser cutting of glass fiber reinforced reactive injection moulded (RRIM)-polyurethanes which are used e.g. in car industry for bumpers, spoilers, and further components is described. A Comparison with other cutting techniques as there are water jet cutting, milling, punching, sawing, cutting with conventional knife and with ultrasonic excited knife is given. Parameters which mainly influence cutting results e.g. laser power, cutting speed, gas nature and pressure will be discussed. The problematic nature in characterising micro and macro geometry of laser cut edges of fiber reinforced plastic (FRP) is explained. The topography of cut edges is described and several characteristic values are introduced to specify the obtained working quality. The surface roughness of laser cut edges is measured by both, an optical and a mechanical sensor and their reliabilities are compared.

  20. Determination of mechanical properties of some glass fiber reinforced plastics suitable to Wind Turbine Blade construction

    NASA Astrophysics Data System (ADS)

    Steigmann, R.; Savin, A.; Goanta, V.; Barsanescu, P. D.; Leitoiu, B.; Iftimie, N.; Stanciu, M. D.; Curtu, I.

    2016-08-01

    The control of wind turbine's components is very rigorous, while the tower and gearbox have more possibility for revision and repairing, the rotor blades, once they are deteriorated, the defects can rapidly propagate, producing failure, and the damages can affect large regions around the wind turbine. This paper presents the test results, performed on glass fiber reinforced plastics (GFRP) suitable to construction of wind turbine blades (WTB). The Young modulus, shear modulus, Poisson's ratio, ultimate stress have been determined using tensile and shear tests. Using Dynamical Mechanical Analysis (DMA), the activation energy for transitions that appear in polyester matrix as well as the complex elastic modulus can be determined, function of temperature.

  1. 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.

  2. [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.

  3. 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.

  4. Biodegradable polyester-based eco-composites containing hemp fibers modified with macrocyclic oligomers

    NASA Astrophysics Data System (ADS)

    Conzatti, Lucia; Utzeri, Roberto; Hodge, Philip; Stagnaro, Paola

    2016-05-01

    An original compatibilizing pathway for hemp fibers/poly(1,4-butylene adipate-co-terephtalate) (PBAT) eco-composites was explored exploiting the capability of macrocyclic oligomers (MCOs), obtained by cyclodepolymerization (CDP) of PBAT at high dilution, of being re-converted into linear chains by entropically-driven ring-opening polymerization (ED-ROP) that occurs simply heating the MCOS in the bulk. CDP reaction of PBAT was carried out varying solvent, catalyst and reaction time. Selected MCOs were used to adjust the conditions of the ED-ROP reaction. The best experimental conditions were then adopted to modify hemp fibers. Eco-composites based on PBAT and hemp fibers as obtained or modified with PBAT macrocyclics or oligomers were prepared by different process strategies. The best fiber-PBAT compatibility was observed when the fibers were modified with PBAT oligomers before incorporation in the polyester matrix.

  5. Fabrication and physical properties of glass-fiber-reinforced thermoplastics for non-metal-clasp dentures.

    PubMed

    Nagakura, Manamu; Tanimoto, Yasuhiro; Nishiyama, Norihiro

    2016-07-26

    Recently, non-metal-clasp dentures (NMCDs) made from thermoplastic resins such as polyamide, polyester, polycarbonate, and polypropylene have been used as removable partial dentures (RPDs). However, the use of such RPDs can seriously affect various tissues because of their low rigidity. In this study, we fabricated high-rigidity glass-fiber-reinforced thermoplastics (GFRTPs) for use in RPDs, and examined their physical properties such as apparent density, dynamic hardness, and flexural properties. GFRTPs made from E-glass fibers and polypropylene were fabricated using an injection-molding. The effects of the fiber content on the GFRTP properties were examined using glass-fiber contents of 0, 5, 10, 20, 30, 40, and 50 mass%. Commercially available denture base materials and NMCD materials were used as controls. The experimental densities of GFRTPs with various fiber contents agreed with the theoretical densities. Dynamic micro-indentation tests confirmed that the fiber content does not affect the GFRTP surface properties such as dynamic hardness and elastic modulus, because most of the reinforcing glass fibers are embedded in the polypropylene. The flexural strength increased from 55.8 to 217.6 MPa with increasing glass-fiber content from 0 to 50 mass%. The flexural modulus increased from 1.75 to 7.42 GPa with increasing glass-fiber content from 0 to 50 mass%, that is, the flexural strength and modulus of GFRTP with a fiber content of 50 mass% were 3.9 and 4.2 times, respectively, those of unreinforced polypropylene. These results suggest that fiber reinforcement has beneficial effects, and GFRTPs can be used in NMCDs because their physical properties are better than those of controls. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  6. 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.

  7. 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.

  8. [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.

  9. Static and dynamic behavior of carbon fiber reinforced aluminum (CARALL) laminates

    NASA Astrophysics Data System (ADS)

    Dhaliwal, Gurpinder Singh

    The main aim of this research work was to investigate the static and dynamic properties of carbon fiber reinforced aluminum laminates cured without using any external adhesive and acid treatment of aluminum layers. A comprehensive study was undertaken to study the effect of adding epoxy resin rich polyester synthetic surface veil cloth layers on the failure modes and flexural and tensile response of these fiber metal laminates (FMLs). The main purpose of adding veil cloth layers was to prevent the occurrence of galvanic corrosion by avoiding direct contact between aluminum and carbon fiber layers. The addition of veil cloth layers leads to the combined failure of all layers in carbon fiber reinforced aluminum laminates at the same time, whereas the carbon fiber/ epoxy layers break before the failure of aluminum layers in samples cured without using veil cloth layers under tensile loading. The delamination was found to be reduced to a great extent in these laminate configurations due to the addition of veil cloth layers. Thermal residual stress developed during the curing of fiber metal laminates were predicted by utilizing analytical equations and finite element modeling. It was found out that the veil cloth layer does not affect much in reducing the thermal residual stress. Low-velocity impact tests were carried out using a drop-weight impact tower by impacting these fiber metal laminates at the center with three different energy levels to address energy absorption characteristics of these composites. Results showed that these laminates give higher forces and smaller displacement with the addition of polyester veil cloth layers due to reduced delaminated area across all interfaces of aluminum and carbon fiber layers, thus increasing slightly the energy absorption capabilities of these laminates. Primary failure modes observed during impact tests in these FMLs were cracks in the non-impacted aluminum layer, carbon fiber (CFRP) layer breakage and delamination b

  10. Experimental Behavior of Carbon Fiber Reinforced Isolators

    SciTech Connect

    Russo, Gaetano; Pauletta, Margherita; Cortesia, Andrea; Dal Bianco, Alberto

    2008-07-08

    This paper describes an investigation on the experimental behavior of innovative elastomeric isolators reinforced by carbon fiber fabrics. These fabrics are very much lighter than steel plates used in conventional isolators and able to transfer to the adjacent elastomer layers tangential stresses adequate to oppose the transversal deformation of rubber under vertical loads. The isolators are not bonded to the sub- and super-structure (elimination of the steel end-plates), hence their weight and cost are reduced. The experimental investigation is carried out on small-scale isolator prototypes reinforced by quadridirectional carbon fiber fabrics. The isolators are subjected to the following qualification tests prescribed by the Italian Code 'Ordinanza 3274' for steel reinforced isolators: 1) 'Static assessment of the compression stiffness'; 2) 'Static assessment of the shear modulus G'; 3) 'Dynamic assessment of the dynamic shear modulus G{sub din} and of the damping coefficient {xi}; 4) 'Assessment of the G{sub din}-{gamma} and {xi}-{gamma} diagrams by means of dynamic tests'; 5) 'Assessment of creep characteristics'; 6) 'Evaluation of the capacity of sustaining at least 10 cycles'. As a result of the tests, the isolators survived large shear strains, comparable to those expected for conventional isolators.

  11. 76 FR 38612 - Certain Polyester Staple Fiber From the Republic of Korea and Taiwan: Final Results of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-01

    ... International Trade Administration Certain Polyester Staple Fiber From the Republic of Korea and Taiwan: Final... staple fiber (PSF) from the Republic of Korea (Korea) and Taiwan, pursuant to section 751(c) of the... received a notice of intent to participate from DAK Americas, LLC, Palmetto Synthetics LLC, and U.S....

  12. Cohesive fracture model for functionally graded fiber reinforced concrete

    SciTech Connect

    Park, Kyoungsoo; Paulino, Glaucio H.; Roesler, Jeffery

    2010-06-15

    A simple, effective, and practical constitutive model for cohesive fracture of fiber reinforced concrete is proposed by differentiating the aggregate bridging zone and the fiber bridging zone. The aggregate bridging zone is related to the total fracture energy of plain concrete, while the fiber bridging zone is associated with the difference between the total fracture energy of fiber reinforced concrete and the total fracture energy of plain concrete. The cohesive fracture model is defined by experimental fracture parameters, which are obtained through three-point bending and split tensile tests. As expected, the model describes fracture behavior of plain concrete beams. In addition, it predicts the fracture behavior of either fiber reinforced concrete beams or a combination of plain and fiber reinforced concrete functionally layered in a single beam specimen. The validated model is also applied to investigate continuously, functionally graded fiber reinforced concrete composites.

  13. [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

  14. Tungsten fiber reinforced superalloys: A status review

    NASA Technical Reports Server (NTRS)

    Petrasek, D. W.; Signorelli, R. A.

    1981-01-01

    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.

  15. Fiber-Reinforced Superalloys For Rocket Engines

    NASA Technical Reports Server (NTRS)

    Lewis, Jack R.; Yuen, Jim L.; Petrasek, Donald W.; Stephens, Joseph R.

    1990-01-01

    Report discusses experimental studies of fiber-reinforced superalloy (FRS) composite materials for use in turbine blades in rocket engines. Intended to withstand extreme conditions of high temperature, thermal shock, atmospheres containing hydrogen, high cycle fatigue loading, and thermal fatigue, which tax capabilities of even most-advanced current blade material - directionally-solidified, hafnium-modified MAR M-246 {MAR M-246 (Hf) (DS)}. FRS composites attractive combination of properties for use in turbopump blades of advanced rocket engines at temperatures from 870 to 1,100 degrees C.

  16. Radiation effects on carbon fiber reinforced thermoplastics

    SciTech Connect

    Sasuga, Tsuneo; Udagawa, Akira; Seguchi, Tadao

    1993-12-31

    Polyether-ether-ketone (PEEK) and a newly developed thermoplastic polyimide ``new-TPI`` were applied to carbon fiber reinforced plastic (CFRP) as a matrix resin. PEEK and new-TPI showed excellent resistance over 50 MGy to electron irradiation and the crosslinking proceeded predominantly by irradiation. The changes in mechanical properties induced by electron irradiation of the CFRP with the two resins were examined at various temperatures. The flexural strength and modulus measured at {minus}196 and 25{degree}C were scarcely affected up to 120 MGy and both the values measured at high temperature were increased with dose.

  17. 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.

  18. Durable fiber reinforced self-compacting concrete

    SciTech Connect

    Corinaldesi, V.; Moriconi, G

    2004-02-01

    In order to produce thin precast elements, a self-compacting concrete was prepared. When manufacturing these elements, homogenously dispersed steel fibers instead of ordinary steel-reinforcing mesh were added to the concrete mixture at a dosage of 10% by mass of cement. An adequate concrete strength class was achieved with a water to cement ratio of 0.40. Compression and flexure tests were carried out to assess the safety of these thin concrete elements. Moreover, serviceability aspects were taken into consideration. Firstly, drying shrinkage tests were carried out in order to evaluate the contribution of steel fibers in counteracting the high concrete strains due to a low aggregate-cement ratio. Secondly, the resistance to freezing and thawing cycles was investigated on concrete specimens in some cases superficially treated with a hydrophobic agent. Lastly, both carbonation and chloride penetration tests were carried out to assess durability behavior of this concrete mixture.

  19. 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.

  20. Nano-Aramid Fiber Reinforced Polyurethane Foam

    NASA Technical Reports Server (NTRS)

    Semmes, Edmund B.; Frances, Arnold

    2008-01-01

    Closed cell polyurethane and, particularly, polyisocyanurate foams are a large family of flexible and rigid products the result of a reactive two part process wherein a urethane based polyol is combined with a foaming or "blowing" agent to create a cellular solid at room temperature. The ratio of reactive components, the constituency of the base materials, temperature, humidity, molding, pouring, spraying and many other processing techniques vary greatly. However, there is no known process for incorporating reinforcing fibers small enough to be integrally dispersed within the cell walls resulting in superior final products. The key differentiating aspect from the current state of art resides in the many processing technologies to be fully developed from the novel concept of milled nano pulp aramid fibers and their enabling entanglement capability fully enclosed within the cell walls of these closed cell urethane foams. The authors present the results of research and development of reinforced foam processing, equipment development, strength characteristics and the evolution of its many applications.

  1. 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.

  2. Carbon Fiber Reinforced Glass Matrix Composites for Space Based Applications.

    DTIC Science & Technology

    1987-08-31

    Nardone , "Carbon Fiber Reinforced Glass Matrix Composites for Space Based Applications", Office of Naval Research Contract N00014-85-C-0332, Report R86... Nardone and K M. Prewo, "Tensile Performance of Carbon Fiber Reinforced Glass", J. Mater. Sci. accepted for publication, 1987. 27. R. F. Cooper and K

  3. Intracanal reinforcement fiber in pediatric dentistry: a case report.

    PubMed

    Rocha, Rachel de Oliveira; das Neves, Lucimara Teixeira; Marotti, Noely Regina; Wanderley, Marcia Turolla; Corrêa, Maria Salete Nahás Pires

    2004-04-01

    A technique for the restoration of carious primary maxillary incisors using indirect resin composite crowns and intracanal reinforcement fiber is described. Endodontic treatment was previously performed on each tooth. The advantages of using an intracanal reinforcement fiber include resin composite crown reinforcement, translucency, and relative manipulation facility. In addition, the use of indirect resin composite crowns provides good shape and esthetics, as well as reduced chair time for the child. The technique is illustrated in a case report in which indirect resin composite crowns and an intracanal reinforcement fiber are placed in a 3-year-old girl.

  4. Axial quasi-static crushing behaviour of cylindrical woven kenaf fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Abdullah, Noorhaslinda; Ismail, Al Emran

    2017-01-01

    This paper presents the crushing responses of cylindrical woven kenaf fibre reinforced composites under quasi-static compression. Kenaf fiber in the form of yarn is weaved into woven mat. It is then submerged into polyester bath before it is wrapped into a cylindrical shape. There are two important parameters investigated such as number of layers and fiber orientations. According to the experimental results, as expected increasing the number of layers increased the energy absorption performances. However, increasing the fibre orientations from 0o to 45o capable to decrease the energy absorption capability. It is also observed that during progressive collapses, localized buckling is the dominant failure mechanism where there is no large composite fragmentation occurred.

  5. Development of natural fiber reinforced polylactide-based biocomposites

    NASA Astrophysics Data System (ADS)

    Arias Herrera, Andrea Marcela

    Polylactide or PLA is a biodegradable polymer that can be produced from renewable resources. This aliphatic polyester exhibits good mechanical properties similar to those of polyethylene terephthalate (PET). Since 2003, bio-based high molecular weight PLA is produced on an industrial scale and commercialized under amorphous and semicrystalline grades for various applications. Enhancement of PLA crystallization kinetics is crucial for the competitiveness of this biopolymer as a commodity material able to replace petroleum-based plastics. On the other hand, the combination of natural fibers with polymer matrices made from renewable resources, to produce fully biobased and biodegradable polymer composite materials, has been a strong trend in research activities during the last decade. Nevertheless, the differences related to the chemical structure, clearly observed in the marked hydrophilic/hydrophobic character of the fibers and the thermoplastic matrix, respectively, represent a major drawback for promoting strong fiber/matrix interactions. The aim of the present study was to investigate the intrinsic fiber/matrix interactions of PLAbased natural fiber composites prepared by melt-compounding. Short flax fibers presenting a nominal length of ˜1 mm were selected as reinforcement and biocomposites containing low to moderate fiber loading were processed by melt-mixing. Fiber bundle breakage during processing led to important reductions in length and diameter. The mean aspect ratio was decreased by about 50%. Quiescent crystallization kinetics of PLA and biocomposite systems was examined under isothermal and non-isothermal conditions. The nucleating nature of the flax fibers was demonstrated and PLA crystallization was effectively accelerated as the natural reinforcement content increased. Such improvement was controlled by the temperature at which crystallization took place, the liquid-to-solid transition being thermodynamically promoted by the degree of supercooling

  6. Machining of fiber-reinforced composite laminates

    NASA Astrophysics Data System (ADS)

    Won, Myong-Shik

    As fiber-reinforced composite laminates are becoming considerably popular in a wide range of applications, the necessity for machining such materials is increasing rapidly. Due to their microscopical inhomogeneity, anisotropy, and highly abrasive nature, composite laminates exhibit some peculiar types of machining damage. Consequently, the machining of composite laminates requires a different approach from that used for metals and offers a challenge from both an academic and application point of view. In the present work, the drilling of composite laminated plates and the edge trimming of tubular composite laminates were investigated through theoretical analyses and their experimental verification. First, a drilling process model using linear elastic fracture mechanics and classical plate bending theory was developed to predict the critical thrust value responsible for the onset of delamination during the drilling of composite laminates with pre-drilled pilot holes. Experiments using stepped drills, which can utilize the effectiveness of such pilot holes, were conducted on composite laminates. Reasonably good agreement was found between the results of the process model and the tests. Second, the development of a model-based intelligent control strategy for the efficient drilling of composite laminates was explored by experiments and analyses. In this investigation, mathematical models were created to relate the drilling forces to cutting parameters and to identify the different process stages. These models predicted the degree of thrust force regulation to prevent delamination. Third, the edge trimming of thin-walled tubular composite laminates was modeled and analyzed for estimating the critical cutting force at the initiation of longitudinal cracking. A series of full-scale edge trimming tests were conducted on tubular composite specimens to assess the current approach and to obtain basic machining data for various composite laminates. The present study provides

  7. Ductility of nonmetallic hybrid fiber composite reinforcement for concrete

    NASA Astrophysics Data System (ADS)

    Tepfers, R.; Tamužs, V.; Apinis, R.; Vilks, U.; Modniks, J.

    1996-03-01

    Reinforcing units, FRP, of unidirectional fiber composites for concrete have elastic behavior up to tensile failure. For safety reasons an elongation of 3% at maximum load is usually required for the reinforcement. Ductile behavior with the necessary elongation and stress hardening could be obtained with braided fiber strands around a core of foam plastic, thin glass fiber cylindrical shell, or unidirectional carbon fibers. Braids around a porous core reveal the ductility when epoxy resin breaks up and collapse of core enables the braids to rotate. The same seems to happen at that cross section, where carbon fiber core breaks in tension. The best result is obtained using a cylindrical glass fiber reinforced core shell surrounded with aramid fiber braid.

  8. 76 FR 5331 - Certain Polyester Staple Fiber From Taiwan: Extension of Time Limit for Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-31

    ... International Trade Administration Certain Polyester Staple Fiber From Taiwan: Extension of Time Limit for... later than January 31, 2011. Extension of Time Limit for Preliminary Results Section 751(a)(3)(A) of the... published in the Federal Register. If it is not practicable to complete the review within these time...

  9. 77 FR 21733 - Certain Polyester Staple Fiber From Taiwan: Extension of Time Limit for Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-11

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Certain Polyester Staple Fiber From Taiwan: Extension of Time Limit for Preliminary Results of Antidumping Duty Administrative Review AGENCY: Import Administration, International Trade Administration, Department...

  10. CREATION OF MUSIC WITH FIBER REINFORCED CONCRETE

    NASA Astrophysics Data System (ADS)

    Kato, Hayato; Takeuchi, Masaki; Ogura, Naoyuki; Kitahara, Yukiko; Okamoto, Takahisa

    This research focuses on the Fiber Reinforcement Concrete(FRC) and its performance on musical tones. Thepossibility of future musical instruments made of this concrete is discussed. Recently, the technical properties of FRC had been improved and the different production styles, such as unit weight of binding material and volume of fiber in the structure, hardly affects the results of the acoustics. However, the board thickness in the FRC instruments is directly related with the variety of musical tone. The FRC musical effects were compared with those produced with wood on wind instruments. The sounds were compared with those produced with woodwind instruments. The sound pressure level was affected by the material and it becomes remarkably notorious in the high frequency levels. These differences had great influence on the spectrum analysis of the tone in the wind instruments and the sensory test. The results from the sensory test show dominant performances of brightness, beauty and power in the FRC instruments compared with those made of wood.

  11. Phsyical and Mechanical Properties of Fiber-Glass Reinforced Plastics (A Collection of Articles),

    DTIC Science & Technology

    REINFORCED PLASTICS , MECHANICAL PROPERTIES), LAMINATED PLASTICS , GLASS TEXTILES, TEST METHODS, SILICONE PLASTICS , POLYESTER PLASTICS , PHENOLIC... PLASTICS , EPOXY RESINS, POLYVINYL CHLORIDE, STYRENE PLASTICS , POLYAMIDE PLASTICS , TENSILE PROPERTIES, COMPRESSIVE PROPERTIES, SHEAR STRESSES, NONDESTRUCTIVE TESTING, ULTRANSONIC RADIATION, FIRE RESISTANT MATERIALS, USSR

  12. Graphite fiber reinforced glass matrix composites for aerospace applications

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Bacon, J. F.; Dicus, D. L.

    1979-01-01

    The graphite fiber reinforced glass matrix composite system is described. Although this composite is not yet a mature material, it possesses low density, attractive mechanical properties at elevated temperatures, and good environmental stability. Properties are reported for a borosilicate glass matrix unidirectionally reinforced with 60 volume percent HMS graphite fiber. The flexural strength and fatigue characteristics at room and elevated temperature, resistance to thermal cycling and continuous high temperature oxidation, and thermal expansion characteristics of the composite are reported. The properties of this new composite are compared to those of advanced resin and metal matrix composites showing that graphite fiber reinforced glass matrix composites are attractive for aerospace applications.

  13. 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.

  14. 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.

  15. Glass matrix composites. I - Graphite fiber reinforced glass

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Bacon, J. F.

    1978-01-01

    An experimental program is described in which graphite fibers of Hercules HMS and HTS, Thornel 300, and Celanese DG-12 were used to reinforce, both uniaxially and biaxially, borosilicate pyrex glass. Composite flexural strength distribution, strength as a function of test temperature, fracture toughness and oxidative stability were determined and shown to be primarily a function of fiber type and the quality of fiber-matrix bond formed during composite fabrication. It is demonstrated that the graphite fiber reinforced glass system offers unique possibilities as a high performance structural material.

  16. 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

  17. 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

  18. 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

  19. Kenaf/recycled Jute Natural Fibers Unsaturated Polyester Composites: Water Absorption/dimensional Stability and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Osman, Ekhlas A.; Vakhguelt, Anatoli; Sbarski, Igor; Mutasher, Saad A.

    2012-03-01

    Effects of water absorption on the flexural properties of kenaf-unsaturated polyester composites and kenaf/recycled jute-unsaturated polyester composites were investigated. In the hybrid composites, the total fiber content was fixed to 20 wt%. In this 20 wt%, the addition of jute fiber varied from 0 to 75%, with increment of 25%. The result demonstrates the water absorption and the thickness swelling increased with increase in immersion time. Effects of water absorption on flexural properties of kenaf fiber composites can be reduced significantly with incorporation of recycled jute in composites formulation. The process of absorption of water was found to approach Fickian diffusion behavior for both kenaf composites and hybrid composites.

  20. Modeling of Uniaxial Compression of Fiber Reinforcements using Finite Strains

    NASA Astrophysics Data System (ADS)

    Comas-Cardona, S.; Le Grognec, P.; Binétruy, C.; Krawczak, P.

    2007-04-01

    Liquid Composite Molding (LCM) processes are increasingly used to produce composite parts. Most of those processes involve compression of the fiber reinforcement and resin flow. In order to accurately model LCM processes, a good knowledge of fiber reinforcement behavior in compression is required. Several models have already been published, but none of them include permanent deformations. Also because of the large deformation involved in the processes, a finite strain formulation is proposed. Results are given for a glass twill-weave fabric.

  1. Fiber Reinforcement for Rapid Stabilization of Soft Clay Soils

    DTIC Science & Technology

    2006-11-01

    AFRL-RX-TY-TP-2009-4603 FIBER REINFORCEMENT FOR RAPID STABILIZATION OF SOFT CLAY SOILS Susan D. Rafalko, Thomas L. Brandon...Include area code) 14-NOV-2006 Technical Paper 11-AUG-2006 -- 14-NOV-2006 Fiber Reinforcement for Rapid Stabilization of Soft Clay Soils FA8651-04-C...military has sought methods for rapid stabilization of weak soils for support of its missions worldwide. Over the past 60 years, cement and lime have

  2. Fiber reinforced superalloys for rocket engines

    NASA Technical Reports Server (NTRS)

    Petrasek, Donald W.; Stephens, Joseph R.

    1988-01-01

    High-pressure turbopumps for advanced reusable liquid-propellant rocket engines such as that for the Space Shuttle Main Engine (SSME) require turbine blade materials that operate under extreme conditions of temperature, hydrogen environment, high-cycle fatigue loading, thermal fatigue and thermal shock. Such requirements tax the capabilities of current blade materials. Based on projections of properties for tungsten fiber reinforced superalloy (FRS) composites, it was concluded that FRS turbine blades offer the potential of a several-fold increase in life and over a 200C increase in temperature capability over current SSME blade material. FRS composites were evaluated with respect to mechanical property requirements for SSME blade applications. Compared to the current blade material, the thermal shock resistance of FRS materials is excellent, two to nine times better, and their thermal fatigue resistance is equal to or higher than the current blade material. FRS materials had excellent low and high-cycle fatigue strengths, and thermal shock-induced surface microcracks had no influence on their fatigue strength. The material also exhibited negligible embrittlement when exposed to a hydrogen environment.

  3. Fiber reinforced superalloys for rocket engines

    NASA Technical Reports Server (NTRS)

    Petrasek, Donald W.; Stephens, Joseph R.

    1989-01-01

    High pressure turbopumps for advanced reusable liquid propellant rocket engines such as that for the Space Shuttle Main Engine (SSME) require turbine blade materials that operate under extreme conditions of temperature, hydrogen environment, high-cycle fatigue loading, thermal fatigue and thermal shock. Such requirements tax the capabilities of current blade materials. Based on projections of properties for tungsten fiber reinforced superalloy (FRS) composites, it was concluded that FRS turbine blades offer the potential of a several fold increase in life and over a 200 C increase in temperature capability over the current SSME blade material. FRS composites were evaluated with respect to mechanical property requirements for SSME blade applications. Compared to the current blade material, the thermal shock resistance of FRS materials is excellent, two to nine times better, and their thermal fatigue resistance is equal to or higher than the current blade material. FRS materials had excellent low and high-cycle fatigue strengths, and thermal shock-induced surface microcracks had no influence on their fatigue strength. The material also exhibited negligible embrittlement when exposed to a hydrogen environment.

  4. CODIFICATION OF FIBER REINFORCED COMPOSITE PIPING

    SciTech Connect

    Rawls, G.

    2012-10-10

    The goal of the overall project is to successfully adapt spoolable FRP currently used in the oil industry for use in hydrogen pipelines. The use of FRP materials for hydrogen service will rely on the demonstrated compatibility of these materials for pipeline service environments and operating conditions. The ability of the polymer piping to withstand degradation while in service, and development of the tools and data required for life management are imperative for successful implementation of these materials for hydrogen pipeline. The information and data provided in this report provides the technical basis for the codification for fiber reinforced piping (FRP) for hydrogen service. The DOE has invested in the evaluation of FRP for the delivery for gaseous hydrogen to support the development of a hydrogen infrastructure. The codification plan calls for detailed investigation of the following areas: System design and applicable codes and standards; Service degradation of FRP; Flaw tolerance and flaw detection; Integrity management plan; Leak detection and operational controls evaluation; Repair evaluation. The FRP codification process started with commercially available products that had extensive use in the oil and gas industry. These products have been evaluated to assure that sufficient structural integrity is available for a gaseous hydrogen environment.

  5. Interface Characterization in Fiber-Reinforced Polymer-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Naya, F.; Molina-Aldareguía, J. M.; Lopes, C. S.; González, C.; LLorca, J.

    2017-01-01

    A novel methodology is presented and applied to measure the shear interface strength of fiber-reinforced polymers. The strategy is based in fiber push-in tests carried out on the central fiber of highly-packed fiber clusters with hexagonal symmetry, and it is supported by a detailed finite element analysis of the push-in test to account for the influence of hygrothermal residual stresses, fiber constraint and fiber anisotropy on the interface strength. Examples of application are presented to determine the shear interface strength in carbon and glass fiber composites reinforced with either thermoset or thermoplastic matrices. In addition, the influence of the environment (either dry or wet conditions) on the interface strength in C/epoxy composites is demonstrated.

  6. Characterization and design of steel fiber reinforced shotcrete in tunnelling

    SciTech Connect

    Casanova, P.A.; Rossi, P.C.

    1995-12-31

    A design procedure of steel fiber reinforced shotcrete tunnel linings is proposed. It is based on the analysis of a cracked section. The tensile behavior of shotcrete after cracking is obtained by a uniaxial tension test on cored notched samples. As for usual reinforced concrete structures an interaction diagram (moment-axial load) is determined.

  7. 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.

  8. Mechanical strength of additive manufactured carbon fiber reinforced polyetheretherketone

    NASA Astrophysics Data System (ADS)

    Chumaevskii, A. V.; Tarasov, S. Yu.; Filippov, A. V.; Kolubaev, E. A.; Rubtsov, V. E.; Eliseev, A. A.

    2016-11-01

    Mechanical properties of both pure and chopped carbon fiber reinforced polyetheretherketone samples have been carried out. It was shown that the reinforcement resulted in increasing the elasticity modulus, compression and tensile ultimate strength by a factor of 3.5, 2.9 and 2.8, respectively. The fracture surfaces have been examined using both optical and scanning electron microscopy.

  9. Predicting the Coefficient of Thermal Expansion of Pultruded Composites with a Natural-Fiber Reinforcement

    NASA Astrophysics Data System (ADS)

    Zamri, M. H.; Akil, H. Md; Safiee, S.; Ishak, Z. A. M.; Bakar, A. A.

    2014-11-01

    Thermal expansion problems for unidirectional pultruded composite samples were studied. The composite materials were subjected to temperatures ranging from 0 to 200°C in order to simulate service conditions. A thermal-mechanical analyzer was employed for gathering experimental data, and the results were compared with those generated using the ANSYS software and micromechanical models. A finite-element analysis (FEA) by utilizing ANSYS was also carried out. The thermal behavior of pultruded jute-fiber-reinforced unsaturated polyester composites was simulated, and the results obtained were then compared with experimental data and predictions provided by several micromechanical models. It is found that the Schapery and Chamis micromechanical models are more efficient in predicting the value of CTE in the longitudinal and transverse directions, respectively.

  10. On processing development for fabrication of fiber reinforced composite, part 2

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung; Hou, Gene J. W.; Sheen, Jeen S.

    1989-01-01

    Fiber-reinforced composite laminates are used in many aerospace and automobile applications. The magnitudes and durations of the cure temperature and the cure pressure applied during the curing process have significant consequences for the performance of the finished product. The objective of this study is to exploit the potential of applying the optimization technique to the cure cycle design. Using the compression molding of a filled polyester sheet molding compound (SMC) as an example, a unified Computer Aided Design (CAD) methodology, consisting of three uncoupled modules, (i.e., optimization, analysis and sensitivity calculations), is developed to systematically generate optimal cure cycle designs. Various optimization formulations for the cure cycle design are investigated. The uniformities in the distributions of the temperature and the degree with those resulting from conventional isothermal processing conditions with pre-warmed platens. Recommendations with regards to further research in the computerization of the cure cycle design are also addressed.

  11. Stronger Carbon Fibers for Reinforced Plastics

    NASA Technical Reports Server (NTRS)

    Cagliostro, D. E.; Lerner, N. R.

    1983-01-01

    Process makes fibers 70 percent stronger at lower carbonization temperature. Stronger carbon fibers result from benzoic acid pretreatment and addition of acetylene to nitrogen carbonizing atmosphere. New process also makes carbon fibers of higher electrical resistance -- an important safety consideration.

  12. Microscopic study of surface degradation of glass fiber-reinforced polymer rods embedded in concrete castings subjected to environmental conditioning

    SciTech Connect

    Bank, L.C.; Puterman, M.

    1997-12-31

    The surface degradation of glass fiber-reinforced polymer (GFRP) pultruded rods when embedded in concrete castings and subjected to environmental conditioning is discussed in this paper. Investigation of the degradation of the GFRP rods were performed using optical microscopy and scanning electron microscopy (SEM). Unidirectionally reinforced pultruded rods (6.3- and 12.7-mm diameters) containing E-glass fibers in polyester and vinylester matrices were conditioned at standard laboratory conditions (21 C, 65% relative humidity) or submerged in aqueous solutions (tap water) at 80 C for durations of 14 and 84 days. Observations of the surfaces and cross-sections of the rods by optical microscopy and SEM revealed a variety of degradation phenomena. Embedded hygrothermally conditioned rods were found to have developed surface blisters of different sizes and depths. SEM studies of the surface revealed degradation of the polymer matrix material and exposure and degradation of the fibers close to the surface of the rods. The rods with the vinylester resin matrix showed less extensive degradation than those with the polyester resin matrix; however, the degradation characteristics of the two types of rods appear to be similar.

  13. Nondestructive Evaluation of Fiber Reinforced Composites. A State-of-the-Art Survey. Volume 1. NDE of Graphite Fiber-Reinforced Plastic Composites. Part 1. Radiography and Ultrasonics

    DTIC Science & Technology

    1982-03-01

    composites (Ref. 1) and by the can be large, and secondary operations can be mini- Army on glass fiber reinforced composites (Ref. 2). This mized. Composites...structural characteristics of ceramic materials, and updates of carbon/carbon com- composites. posites and glass fiber reinforced composites. Because of...the large amount of literature available on graphite While glass fiber reinforced plastic composites fiber reinforced composites, this particular volume

  14. High-Temperature Creep Behavior Of Fiber-Reinforced Niobium

    NASA Technical Reports Server (NTRS)

    Petrasek, Donald W.; Titran, Robert H.

    1990-01-01

    Study conducted to determine feasibility of using composite materials in advanced space power systems, described in 22-page report. Tungsten fibers reduce creep and mass in advanced power systems. Reinforcing niobium alloys with tungsten fibers increases their resistances to creep by factors of as much as 10.

  15. Material Properties for Fiber-Reinforced Silica Aerogels

    NASA Technical Reports Server (NTRS)

    White, Susan; Rouanet, Stephane; Moses, John; Arnold, James O. (Technical Monitor)

    1994-01-01

    Ceramic fiber-reinforced silica aerogels are novel materials for high performance insulation, including thermal protection materials. Experimental data are presented for the thermal and mechanical properties, showing the trends exhibited over a range of fiber loadings and silica aerogel densities. Test results are compared to that of unreinforced bulk aerogels.

  16. Carbon nanotube reinforced polyacrylonitrile and poly(etherketone) fibers

    NASA Astrophysics Data System (ADS)

    Jain, Rahul

    The graphitic nature, continuous structure, and high mechanical properties of carbon nanotubes (CNTs) make them good candidate for reinforcing polymer fiber. The different types of CNTs including single-wall carbon nanotubes (SWNTs), few-wall carbon nanotubes (FWNTs), and multi-wall carbon nanotubes (MWNTs), and carbon nanofibers (CNFs) differ in terms of their diameter and number of graphitic walls. The desire has been to increase the concentration of CNTs as much as possible to make next generation multi-functional materials. The work in this thesis is mainly focused on MWNT and CNF reinforced polyacrylonitrile (PAN) composite fibers, and SWNT, FWNT, and MWNT reinforced poly(etherketone) (PEK) composite fibers. To the best of our knowledge, this is the first study to report the spinning of 20% MWNT or 30% CNF reinforced polymer fiber spun using conventional fiber spinning. Also, this is the first study to report the PEK/CNT composite fibers. The fibers were characterized for their thermal, tensile, mechanical, and dynamic mechanical properties. The fiber structure and morphology was studied using WAXD and SEM. The effect of two-stage heat drawing, sonication time for CNF dispersion, fiber drying temperature, and molecular weight of PAN was also studied. Other challenges associated with processing high concentrations of solutions for making composite fibers have been identified and reported. The effect of CNT diameter and concentration on fiber spinnability and electrical conductivity of composite fiber have also been studied. This work suggests that CNT diameter controls the maximum possible concentration of CNTs in a composite fiber. The results show that by properly choosing the type of CNT, length of CNTs, dispersion of CNTs, fiber spinning method, fiber draw ratio, and type of polymer, one can get electrically conducting fibers with wide range of conductivities for different applications. The PEK based control and composite fibers possess high thermal

  17. Studies on natural fiber reinforced polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Patel, R. H.; Kapatel, P. M.; Machchhar, A. D.; Kapatel, Y. A.

    2016-05-01

    Natural fiber reinforced composites show increasing importance in day to days applications because of their low cost, lightweight, easy availability, non-toxicity, biodegradability and environment friendly nature. But these fibers are hydrophilic in nature. Thus they have very low reactivity and poor compatibility with polymers. To overcome these limitations chemical modifications of the fibers have been carried out. Therefore, in the present work jute fibers have chemically modified by treating with sodium hydroxide (NaOH) solutions. These treated jute fibers have been used to fabricate jute fiber reinforced epoxy composites. Mechanical properties like tensile strength, flexural strength and impact strength have been found out. Alkali treated composites show better properties compare to untreated composites.

  18. Noncontact detection of Teflon inclusions in glass-fiber-reinforced polymer composites using terahertz imaging.

    PubMed

    Zhang, Jin; Wang, Jie; Han, Xiaohui; Cui, Hong-Liang; Shi, Changcheng; Zhang, Jinbo; Shen, Yan

    2016-12-20

    We employed terahertz (THz) time-domain spectroscopy (TDS) imaging technology, a new nondestructive testing method, to detect the inclusions of glass-fiber-reinforced polymer (GFRP) composites. The refractive index and absorption coefficient of two types of GFRP composites (epoxy GFRP composites and polyester GFRP composites) were first extracted, and GFRP composites with Teflon inclusions were examined, including an epoxy GFRP solid panel with a smaller Teflon inclusion hidden behind a larger Teflon inclusion, and polyester GFRP solid panels with Teflon inclusions of various sizes, at different depths. It was experimentally demonstrated that THz TDS imaging technology could clearly detect a smaller inclusion hidden behind a larger inclusion. When the reflected THz pulse from the inclusion did not overlap with that from the front surface of the sample, removal of the latter before Fourier transform was shown to be helpful in imaging the inclusions. With sufficiently strong incident THz radiation, inclusion insertion depth had little impact on the ability of the THz wave to detect inclusions. However, as the thickness of the inclusion became thinner, the inclusion detection ability of the THz wave deteriorated. In addition, with a combination of reflected C-scan imaging and B-scan imaging using the reflected time-domain waveform, both the lateral sizes and locations of the inclusions and the depths and thicknesses of the inclusions were clearly ascertained.

  19. 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.

  20. Fused Deposition Technique for Continuous Fiber Reinforced Thermoplastic

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    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.

  1. 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.

  2. 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.

  3. Fiber-Reinforced Concrete For Hardened Shelter Construction

    DTIC Science & Technology

    1993-02-01

    not limited to, steel, nylon, polypropylene, carbon, glass , and steel fiber - mat matrices. Based on this literature review, areas where research is...reinforce concrete in a wide range of areas, from large size tanks such as swimming pools to roofing system tiles and shingles . 3. Polymeric Fibers ...Page 1 Steel Mat Fiber Matrix Used In Test Beam Types MI And M2 ................ 12 2 Test Beam Cross-Sections. Test Phases I And H

  4. Carbon Fiber Reinforced Glass Matrix Composites for Satellite Applications

    DTIC Science & Technology

    1992-06-01

    graphite basal planes. On the other hand, a high elastic modulus fiber derived from a mesophase pitch precursor, such as P-100, has a radial...and B. V. Perov. Elsevier Science Publishers B. V., Amsterdam, 1985. 2. B. Rand, "Carbon Fibres from Mesophase Pitch " pp. 495-575 in ibid.. 3. W. K...HMU fiber and the other reinforced with pitch -based fiber (P- 100 or FT700), will be described and compared with respect to various features of the

  5. Fretting maps of glass fiber-reinforced composites

    SciTech Connect

    Turki, C.; Salvia, M.; Vincent, L.

    1993-12-31

    Industrial development of new materials are often limited due to an insufficient knowledge in their functional properties. The paper deals with fretting behavior of glass fiber reinforced epoxy/metal contacts. Fretting is a plague for all industries, especially in the case of quasi-static loadings. Furthermore friction testing under small displacements appeared well fitted to understand the effect of fiber orientations and to relate results to microstructure (fiber, matrix and interface).

  6. [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.

  7. Evaluation of Polyester Resin, Epoxy, and Cement Grouts for Embedding Reinforcing Steel Bars in Hardened Concrete

    DTIC Science & Technology

    1990-01-01

    Ultg IFILE COPY REPAIR, EVALUATION, MAINTENANCE, AND REHABILITATION RESEARCH PROGRAM ofEn in s TECHNICAL REPORT REMR-CS-23 EVALUATION OF POLYESTER...WESSC-85-01/TV-66369A Civil Works Research Work Unit 32303 The following two letters used a5 part of the number designating technical reports of... research publisher? under the Repair, Evaluation, Maintenance, and Rehabilitation (REMR) Research Progr-m identify the problem area under which the report

  8. Fatigue strength of woven kenaf fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Ismail, A. E.; Aziz, M. A. Che Abdul

    2015-12-01

    Nowadays, green composites provide alternative to synthetic fibers for non-bearing and load-bearing applications. According to literature review, lack of information is available on the fatigue performances especially when the woven fiber is used instead of randomly oriented fibers. In order to overcome this problem, this paper investigates the fatigue strength of different fiber orientations and number of layers of woven kenaf fiber reinforced composites. Four types of fiber orientations are used namely 0°, 15°, 30° and 45°. Additionally, two numbers of layers are also considered. It is revealed that the fatigue life has no strong relationship with the fiber orientations. For identical fiber orientations, the fatigue life can be predicted considerably using the normalized stress. However as expected, the fatigue life enhancement occur when the number of layer is increased.

  9. Nano-Fiber Reinforced Enhancements in Composite Polymer Matrices

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    2009-01-01

    Nano-fibers are used to reinforce polymer matrices to enhance the matrix dependent properties that are subsequently used in conventional structural composites. A quasi isotropic configuration is used in arranging like nano-fibers through the thickness to ascertain equiaxial enhanced matrix behavior. The nano-fiber volume ratios are used to obtain the enhanced matrix strength properties for 0.01,0.03, and 0.05 nano-fiber volume rates. These enhanced nano-fiber matrices are used with conventional fiber volume ratios of 0.3 and 0.5 to obtain the composite properties. Results show that nano-fiber enhanced matrices of higher than 0.3 nano-fiber volume ratio are degrading the composite properties.

  10. [Improving fiber adhesion by surface oxidation in carbon fiber reinforced bone cement].

    PubMed

    Hopf, T; Büttner, S; Brill, W

    1989-01-01

    The mechanical superiority of carbon fiber reinforced PMMA containing additional apatite was shown previously. For further improvement these carbon fibers were now submitted to a superficial oxidation treatment by HNO3. A closer contact between the carbon fibers and PMMA and even trabeculae-like adhesions were detected by Scanning Electron Microscopy. The fatigue strength of the carbon fiber reinforced bone cement could be increased at 17% by this oxidation treatment. This increase, however, is less than that observed in the case of other fiber reinforced composites. Most likely this is caused by the pronounced polymerisation contraction of PMMA. Further improvement of the adhesion of the fibers to cement may be achieved by different oxidation techniques, further extraction of foreign substances or graft polymerization of the carbon fibers by PMMA or other polymers.

  11. Investigation of Polymer Resin/Fiber Compatibility in Natural Fiber Reinforced Composite Automotive Materials

    SciTech Connect

    Fifield, Leonard S.; Huang, Cheng; Simmons, Kevin L.

    2010-01-01

    Natural fibers represent a lower density and potentially lower cost alternative to glass fibers for reinforcement of polymers in automotive composites. The high specific modulus and strength of bast fibers make them an attractive option to replace glass not only in non-structural automotive components, but also in semi-structural and structural components. Significant barriers to insertion of bast fibers in the fiber reinforced automotive composite market include the high moisture uptake of this lignocellulosic material relative to glass and the weak inherent interface between natural fibers and automotive resins. This work seeks to improve the moisture uptake and resin interfacing properties of natural fibers through improved fundamental understanding of fiber physiochemical architecture and development of tailored fiber surface modification strategies.

  12. Fatigue strengths of particulate filler composites reinforced with fibers.

    PubMed

    Bae, Ji-Myung; Kim, Kyoung-Nam; Hattori, Masayuki; Hasegawa, Koji; Yoshinari, Masao; Kawada, Eiji; Oda, Yutaka

    2004-06-01

    The aim of this study was to evaluate the dynamic fatigue strengths at 10(5) cycles and the strains of particulate filler composite resins with and without reinforcing fibers. An UHMWPE (Ribbond), a polyaromatic polyamide fiber (Fibreflex), and three glass fibers (GlasSpan, FibreKor, Vectris Frame) were used to reinforce the particulate filler composite resins. The fatigue properties were measured in three-point bending mode using a servohydraulic universal testing machine at a frequency of 5 Hz, until failure occurred or 10(5) cycles had been completed. The fatigue strengths at 10(5) cycles were determined by the staircase method. The fractured aspects of specimens were evaluated by an optical and scanning electron microscope. The fatigue strengths of particulate filler composite resins were 49-57 MPa, and those of fiber-reinforced were 90-209 MPa. Unidirectional glass fibers showed higher reinforcing effects on the fatigue strengths of composite resins. The strain of UHMWPE-reinforced composite was largest.

  13. Buckling of Fiber Reinforced Composite Plates with Nanofiber Reinforced Matrices

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Murthy, Pappu L. N.

    2010-01-01

    Anisotropic composite plates were evaluated with nanofiber reinforced matrices (NFRM). The nanofiber reinforcement volumes ratio in the matrix was 0.01. The plate dimensions were 20 by 10 by 1.0 in. (508 by 254 by 25.4 mm). Seven different loading condition cases were evaluated: three for uniaxial loading, three for pairs of combined loading, and one with three combined loadings. The anisotropy arose from the unidirectional plates having been at 30 from the structural axis. The anisotropy had a full 6 by 6 rigidities matrix which were satisfied and solved by a Galerkin buckling algorithm. The buckling results showed that the NFRM plates buckled at about twice those with conventional matrix.

  14. Formable woven preforms based on in situ reinforced thermoplastic fibers

    SciTech Connect

    Robertson, C.G.; Souza, J.P. de; Baird, D.G.

    1995-12-01

    Blends of Vectra B950 (VB) and polypropylene (PP) were spun into fibers utilizing a dual extrusion process for use in formable fabric prepregs. Fibers of 50/50 weight composition were processed up to fiber draw ratios of 106. The tensile modulus of these fibers showed positive deviation from the rule of mixtures for draw ratios greater than 40, and the tensile modulus and strength properties did not level off within the range of draw ratios investigated. The fibers, pre-wetted with polypropylene, were woven into fabrics that were subsequently impregnated with polypropylene sheet to form composites. The tensile mechanical properties of these composites were nearly equivalent to those of long glass fiber reinforced polypropylene. At temperatures between 240 and 280{degrees}C, composites of 6.3 wt.% VB proved formable with elongation to break values in excess of 20%. Impregnated fabric composites were successfully thermoformed without noticeable fiber damage, and a combined fabric impregnation / thermoforming process was developed.

  15. 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.

  16. 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.

  17. Thermal shock behavior of fiber-reinforced composites

    SciTech Connect

    Wang, H.; Singh, R.N.; Beecher, S.C.; Dinwiddie, R.B.

    1995-02-01

    The thermal shock behavior of three types of continuous fiber-reinforced ceramic composites (Nextel{trademark} or Nicalon{trademark} fiber-reinforced chemical vapor infiltrated or polymer-derived SiC matrix composites) was studied using the water quench technique. The thermal shock induced damage was characterized by both destructive and nondestructive techniques. As compared with monolithic ceramics, the continuous fiber-reinforced ceramic composites were capable of preventing catastrophic failure caused by thermal shock and were able to retain a significant portion of their original strength at {Delta}{Tau} = 1000{degrees}C. The nondestructive techniques involved measuring the thermal diffusivity by the flash technique and determining the Young`s modulus by the dynamic resonance method. It has been demonstrated that these nondestructive techniques can detect damage induced by thermal shock and are more sensitive in detecting damage in the early stage than the conventional destructive technique of measuring the retained strength.

  18. Durability of waste glass flax fiber reinforced mortar

    SciTech Connect

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

    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 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.

  19. Effect of diameter of glass fibers on flexural properties of fiber-reinforced composites.

    PubMed

    Obukuro, Motofumi; Takahashi, Yutaka; Shimizu, Hiroshi

    2008-07-01

    This study investigated the effect of the diameter of glass fibers on the flexural properties of fiber-reinforced composites. Bar-shaped test specimens of highly filled fiber-reinforced composites (FRCs) and FRC of 30 vol% fiber content were made from a light-cured dimethacrylate monomer liquid (mixture of urethane dimethacrylate and triethylene glycol dimethacrylate) with silanized E-glass fibers (7, 10, 13, 16, 20, 25, 30, and 45 microm in diameter). Flexural strength and elastic modulus were measured. The flexural strength of the highly filled FRCs increased with increasing fiber diameter. In particular, the strengths of highly filled FRCs with 20-, 25-, 30-, and 45-microm-diameter fibers was significantly higher than the others (p<0.05). The flexural strength of FRC of 30 vol% fiber content increased with increasing fiber diameter, except for the FRC with 45-microm-diameter fibers; FRCs with 20-, 25-, and 30-microm-diameter fibers were significantly stronger than the others (p<0.05). Therefore, it was revealed that the diameter of glass fibers significantly affected the flexural properties of fiber-reinforced composites.

  20. Modelling of dimensional stability of fiber reinforced composite materials

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.; Hosangadi, A.

    1982-01-01

    Various methods of predicting the expansion and diffusion properties of composite laminates are reviewed. The prediction equations for continuous fiber composites can be applied to SMC composites as the effective fiber aspect ratio in the latter is large enough. The effect of hygrothermal expansion on the dimensional stability of composite laminates was demonstrated through the warping of unsymmetric graphite/epoxy laminates. The warping is very sensitive to the size of the panel, and to the moisture content which is in turn sensitive to the relative humidity in the environment. Thus, any long term creep test must be carried out in a humidity-controlled environment. Environmental effects in SMC composites and bulk polyester were studied under seven different environments. The SMC composites chosen are SMC-R25, SMC-R40, and SMC-R65.

  1. Skin problems among fiber-glass reinforced plastics factory workers in Japan.

    PubMed

    Minamoto, Keiko; Nagano, Megumi; Inaoka, Tsukasa; Kitano, Takao; Ushijima, Kayo; Fukuda, Yoshiharu; Futatsuka, Makoto

    2002-01-01

    Two surveys, one in winter the other in summer time, examined the skin problems of the entire manual workers (N=148) from 11 small-to-medium sized fiber-glass reinforced plastics (FRP) factories located in Kyushu, Japan. The workers were exposed to unsaturated polyester resin, including styrene and auxiliary agents such as cobalt naphthenate, hardeners such as methyl ethyl ketone peroxides, glass fiber and dust including shortened glass fiber and plastic particles. Eighty-seven workers (58.8%) reported having skin problems (mainly itching or dermatitis) since they started to work in FRP manufacturing and 25 workers had consulted a physician because of their skin problems; one worker was forced to take sick leave because of his severe dermatitis. History of allergic diseases and shorter occupational period (duration of employment) in a FRP factory were associated with greater probability of having a history of work-related skin symptoms. Workers in factories where dust-generating and lamination sites were located in different buildings were significantly less likely to have a history of skin problems than those in factories where the two sites were located in the same building. Of the 67 workers examined in both seasons closed to double the prevalence of dermatitis was found in summer (23.3%) than winter (13.4%).

  2. Renewable agricultural fibers as reinforcing fillers in plastics: Mechanical properties of kenaf fiber-polypropylene composites

    SciTech Connect

    Sanadi, A.R.; Caulfield, D.F.; Jacobson, R.E.; Rowell, R.M. |

    1995-05-01

    Kenaf (Hibiscus cannabinus) is a fast growing annual growth plant that is harvested for its bast fibers. These fibers have excellent specific properties and have potential to be outstanding reinforcing fillers in plastics. In these experiments, the fibers and polypropylene (PP) were blended in a thermokinetic mixer and then injection molded, with the fiber weight fractions varying to 60%. A maleated polypropylene was used to improve the interaction and adhesion between the nonpolar matrix and the polar lignocellulosic fibers. The specific tensile and flexural moduli of a 50% by weight (39% by volume) of kenaf-PP composite compare favorably with a 40% by weight of glass fiber-PP injection-molded composite. These results suggest that kenaf fibers are a viable alternative to inorganic/mineral-based reinforcing fibers as long as the right processing conditions are used and they are used in applications where the higher water absorption is not critical.

  3. Renewable agricultural fibers as reinforcing fillers in plastics: Mechanical properties of Kenaf fiber-polpyropylene composites

    SciTech Connect

    Sanadi, A.R.; Caulfield, D.F.; Jacobson, R.E.

    1995-12-01

    Kenaf (Hibiscus Cannabinus) is a fast growing annual growth plant that is harvested for its bast fibers. These fibers have excellent specific properties and have potential to be outstanding reinforcing fillers in plastics. In our experiments, the fibers and polypropylene (PP) were blended in a thermokinetic mixer and then injection molded, with the fiber weight fractions varying to 60%. A maleated polypropylene was used to improve the interaction and adhesion between the non-polar matrix and the polar lignocellulosic fibers. The specific tensile and flexural moduli of a 50 % by volume (39 % by volume) of kenaf-PP composites compares favorably with a 40 % by weight of glass fiber-PP injection molded composites, These results suggest that kenaf fibers are a viable alternative to inorganic/mineral based reinforcing fibers as long as the right processing conditions are used and for applications where the higher water absorption is not critical.

  4. Automobile materials competition: energy implications of fiber-reinforced plastics

    SciTech Connect

    Cummings-Saxton, J.

    1981-10-01

    The embodied energy, structural weight, and transportation energy (fuel requirement) characteristics of steel, fiber-reinforced plastics, and aluminum were assessed to determine the overall energy savings of materials substitution in automobiles. In body panels, a 1.0-lb steel component with an associated 0.5 lb in secondary weight is structurally equivalent to a 0.6-lb fiber-reinforced plastic component with 0.3 lb in associated secondary weight or a 0.5-lb aluminum component with 0.25 lb of secondary weight. (Secondary weight refers to the combined weight of the vehicle's support structure, engine, braking system, and drive train, all of which can be reduced in response to a decrease in total vehicle weight.) The life cycle transportation energy requirements of structurally equivalent body panels (including their associated secondary weights) are 174.4 x 10/sup 3/ Btu for steel, 104.6 x 10/sup 3/ Btu for fiber-reinforced plastics, and 87.2 x 10/sup 3/ Btu for aluminum. The embodied energy requirements are 37.2 x 10/sup 3/ Btu for steel, 22.1 x 10/sup 3/ Btu for fiber-reinforced plastics, and 87.1 x 10/sup 3/ Btu for aluminum. These results can be combined to yield total energy requirements of 211.6 x 10/sup 3/ Btu for steel, 126.7 x 10/sup 3/ Btu for fiber-reinforced plastics, and 174.3 x 10/sup 3/ Btu for aluminum. Fiber-reinforced plastics offer the greatest improvements over steel in both embodied and total energy requirements. Aluminum achieves the greatest savings in transportation energy.

  5. Surface grafting of Kevlar fibers for improved interfacial properties of fiber-reinforced composites

    SciTech Connect

    Ravichandran, Vasudha.

    1991-01-01

    Matrix-specific chemical modification of the Kevlar fiber surfaces was carried out with the aim of enhancing adhesion, through covalent bonding, to selected thermoset matrix resins such as vinyl ester, unsaturated polyester and epoxy. A two-step grafting method, involving initial metalation followed by subsequent substitution, was used to graft vinyl and epoxy terminated groups onto Kevlar fiber surfaces. The physical changes in fiber surface were characterized by scanning-electron microscopy and surface area measurement and the chemical changes due to grafting were measured by contact angle measurement and neutron activation analysis; high concentrations of double bonds and epoxy groups were measured. The change in interfacial sear strength due to the surface grafting was measured by means of a single fiber pull out test. The results show a nearly twofold increase in the interfacial shear strength due to vinyl terminated grafts in the case of Kevlar/vinyl ester and Kevlar/polyester composites. Kevlar fibers containing the epoxy functionality on the surface had enhanced adhesion to epoxy matrix resin.

  6. Advance study of fiber-reinforced self-compacting concrete

    SciTech Connect

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

    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 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.

  7. 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.

  8. Fiber-reinforced bioactive and bioabsorbable hybrid composites.

    PubMed

    Huttunen, Mikko; Törmälä, Pertti; Godinho, Pedro; Kellomäki, Minna

    2008-09-01

    Bioabsorbable polymeric bone fracture fixation devices have been developed and used clinically in recent decades to replace metallic implants. An advantage of bioabsorbable polymeric devices is that these materials degrade in the body and the degradation products exit via metabolic routes. Additionally, the strength properties of the bioabsorbable polymeric devices decrease as the device degrades, which promotes bone regeneration (according to Wolff's law) as the remodeling bone tissue is progressively loaded. The most extensively studied bioabsorbable polymers are poly-alpha-hydroxy acids. The major limitation of the first generation of bioabsorbable materials and devices was their relatively low mechanical properties and brittle behavior. Therefore, several reinforcing techniques have been used to improve the mechanical properties. These include polymer chain orientation techniques and the use of fiber reinforcements. The latest innovation for bioactive and fiber-reinforced bioabsorbable composites is to use both bioactive and bioresorbable ceramic and bioabsorbable polymeric fiber reinforcement in the same composite structure. This solution of using bioactive and fiber-reinforced bioabsorbable hybrid composites is examined in this study.

  9. 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.

  10. 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

  11. Fabrication of fiber-reinforced composites by chemical vapor infiltration

    SciTech Connect

    Besmann, T.M.; McLaughlin, J.C.; Probst, K.J.; Anderson, T.J.; Starr, T.L.

    1997-12-01

    Silicon carbide-based heat exchanger tubes are of interest to energy production and conversion systems due to their excellent high temperature properties. Fiber-reinforced SiC is of particular importance for these applications since it is substantially tougher than monolithic SiC, and therefore more damage and thermal shock tolerant. This paper reviews a program to develop a scaled-up system for the chemical vapor infiltration of tubular shapes of fiber-reinforced SiC. The efforts include producing a unique furnace design, extensive process and system modeling, and experimental efforts to demonstrate tube fabrication.

  12. Mechanical characterization of commercially made carbon-fiber-reinforced polymethylmethacrylate.

    PubMed

    Saha, S; Pal, S

    1986-01-01

    Acrylic bone cement is significantly weaker and of lower modulus of elasticity than compact bone. It is also weaker in tension than in compression. This limits its use in orthopedics to areas where tensile stresses were minimum. Many authors have shown that addition of small percentages of fiber reinforcement by hand mixing improved the mechanical properties significantly but with variable results. In this investigation we have examined the mechanical properties of machine-mixed, commercially available carbon-fiber-reinforced bone cement. Appropriate samples of normal low-viscosity cement and carbon-fiber-reinforced cement were prepared and tested mechanically. Carbon fiber increased the tensile strength and modulus by 30% and 35.8% respectively. The compression strength and modulus, however, increased by only 10.7%. Similarly, bending and shear strengths improved by 29.5% and 18.5%, respectively. Diametral compression strength, which is an indirect measure of tensile strength, however, showed only 6.2% improvement. The maximum temperature rise during polymerization was also reduced significantly by the fiber reinforcement.

  13. Physical behaviors of fiber reinforcement as applied to tooth stabilization.

    PubMed

    Rudo, D N; Karbhari, V M

    1999-01-01

    This article presents an understanding of the mechanical response of polymer matrix composite materials that are reinforced with fibers that have high levels of failure strain. Also discussed are the basic principles for the use of the materials and techniques to optimize the clinical success for the applications in which these fibers are used to restore and maintain form and function to the masticatory structures.

  14. 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.

  15. Flexural retrofitting of reinforced concrete structures using Green Natural Fiber Reinforced Polymer plates

    NASA Astrophysics Data System (ADS)

    Cervantes, Ignacio

    An experimental study will be carried out to determine the suitability of Green Natural Fiber Reinforced Polymer plates (GNFRP) manufactured with hemp fibers, with the purpose of using them as structural materials for the flexural strengthening of reinforced concrete (RC) beams. Four identical RC beams, 96 inches long, are tested for the investigation, three control beams and one test beam. The first three beams are used as references; one unreinforced, one with one layer of Carbon Fiber Reinforced Polymer (CFRP), one with two layers of CFRP, and one with n layers of the proposed, environmental-friendly, GNFRP plates. The goal is to determine the number of GNFRP layers needed to match the strength reached with one layer of CFRP and once matched, assess if the system is less expensive than CFRP strengthening, if this is the case, this strengthening system could be an alternative to the currently used, expensive CFRP systems.

  16. Initial evaluation of continuous fiber reinforced NiAl composites

    NASA Technical Reports Server (NTRS)

    Noebe, R. D.; Bowman, R. R.; Eldridge, J. I.

    1990-01-01

    NiAl is being evaluated as a potential matrix material as part of an overall program to develop and understand high-temperature structural composites. Currently, continuous fiber composites have been fabricated by the powder cloth technique incorporating either W(218) or single crystal Al2O3 fibers as reinforcements in both binary NiAl and a solute strengthened NiAl(.05 at. pct Zr) matrix. Initial evaluation of these composite systems have included: fiber push-out testing to measure matrix/fiber bond strengths, bend testing to determine strength as a function of temperature and composite structure, and thermal cycling to establish the effect of matrix and fiber properties on composite life. The effect of matrix/fiber bond strength and matrix strength on several composite properties will be discussed.

  17. NATURAL FIBER OR GLASS REINFORCED POLYPROPYLENE COMPOSITES?

    SciTech Connect

    Lorenzi, W.; Di Landro, L.; Casiraghi, A.; Pagano, M. R.

    2008-08-28

    Problems related to the recycle of conventional composite materials are becoming always more relevant for many industrial fields. Natural fiber composites (NFC) have recently gained much attention due to their low cost, environmental gains (eco-compatibility), easy disposal, reduction in volatile organic emissions, and their potential to compete with glass fiber composites (GFC). Interest in natural fibers is not only based over ecological aspects. NFC have good mechanical performances in relation to their low specific weight and low price. A characterization of mechanical properties, dynamic behavior, and moisture absorption is presented.

  18. 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.

  19. Fiber Reinforced Composites for Insulation and Structures

    NASA Technical Reports Server (NTRS)

    Broughton, Roy M., Jr.

    2005-01-01

    The work involves two areas: Composites, optimum fiber placement with initial construction of a pressure vessel, and the general subject of insulation, a continual concern in harsh thermal environments. Insulation

  20. Dynamic mechanical analysis of fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Reed, K. E.

    1979-01-01

    Dynamic mechanical and thermal properties were determined for unidirectional epoxy/glass composites at various fiber orientation angles. Resonant frequency and relative logarithmic decrement were measured as functions of temperature. In low angle and longitudinal specimens a transition was observed above the resin glass transition temperature which was manifested mechanically as an additional damping peak and thermally as a change in the coefficient of thermal expansion. The new transition was attributed to a heterogeneous resin matrix induced by the fiber. The temperature span of the glass-rubber relaxation was found to broaden with decreasing orientation angle, reflecting the growth of fiber contribution and exhibiting behavior similar to that of Young's modulus. The change in resonant frequency through the glass transition was greatest for samples of intermediate fiber angle, demonstrating behavior similar to that of the longitudinal shear modulus.

  1. Plastic matrix composites with continuous fiber reinforcement

    SciTech Connect

    1991-09-19

    Most plastic resins are not suitable for structural applications. Although many resins are extremely tough, most lack strength, stiffness, and deform under load with time. By mixing strong, stiff, fibrous materials into the plastic matrix, a variety of structural composite materials can be formed. The properties of these composites can be tailored by fiber selection, orientation, and other factors to suit specific applications. The advantages and disadvantages of fiberglass, carbon-graphite, aramid (Kevlar 49), and boron fibers are summarized.

  2. 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

  3. NDE Elastic Properties of Fiber-Reinforced Composite Materials

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.

    1995-01-01

    Fiber-reinforced composites are increasingly replacing metallic alloys as structural materials for primary components of fracture-critical structures. This trend is a result of the growing understanding of material behavior and recognition of the desirable properties of composites. A research program was conducted on NDE methods for determining the elastic properties of composites.

  4. Strength Analysis of Glass-Fiber-Reinforced Plastic during Buckling,

    DTIC Science & Technology

    An algorithm is developed for calculating and analyzing the stress tensor by the experimental function of deflections during the buckling of glass ... fiber -reinforced plastic shells loaded with a hydrostatic load. Malmeyster’s theory of strength is used to qualitatively establish the possible points of shell failure. (Author-PL)

  5. Apatite bone cement reinforced with calcium silicate fibers.

    PubMed

    Motisuke, Mariana; Santos, Verônica R; Bazanini, Naiana C; Bertran, Celso A

    2014-10-01

    Several research efforts have been made in the attempt to reinforce calcium phosphate cements (CPCs) with polymeric and carbon fibers. Due to their low compatibility with the cement matrix, results were not satisfactory. In this context, calcium silicate fibers (CaSiO3) may be an alternative material to overcome the main drawback of reinforced CPCs since, despite of their good mechanical properties, they may interact chemically with the CPC matrix. In this work CaSiO3 fibers, with aspect ratio of 9.6, were synthesized by a reactive molten salt synthesis and used as reinforcement in apatite cement. 5 wt.% of reinforcement addition has increased the compressive strength of the CPC by 250% (from 14.5 to 50.4 MPa) without preventing the cement to set. Ca and Si release in samples containing fibers could be explained by CaSiO3 partial hydrolysis which leads to a quick increase in Ca concentration and in silica gel precipitation. The latter may be responsible for apatite precipitation in needle like form during cement setting reaction. The material developed presents potential properties to be employed in bone repair treatment.

  6. Guided waves characterization of bamboo fibers reinforced composites

    NASA Astrophysics Data System (ADS)

    Marchi, L. De; Marzani, A.; Perelli, A.; Testoni, N.; Speciale, N.

    2012-05-01

    In the present study, an inverse procedure based on ultrasonic guided wave propagation is proposed for the bamboo fibers reinforced composites characterization. The procedure consists of an optimization problem in which the discrepancy between the experimental dispersion curves and those predicted through a numerical formulation is minimized.

  7. Elastic/viscoplastic constitutive model for fiber reinforced thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Gates, T. S.; Sun, C. T.

    1991-01-01

    A constitutive model to describe the elastic/viscoplastic behavior of fiber-reinforced thermoplastic composites under plane stress conditions is presented. Formulations are given for quasi-static plasticity and time-dependent viscoplasticity. Experimental procedures required to generate the necessary material constants are explained, and the experimental data is compared to the predicted behavior.

  8. An Assessment of Self-Healing Fiber Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Smith, Joseph G., Jr.

    2012-01-01

    Several reviews and books have been written concerning self-healing polymers over the last few years. These have focused primarily on the types of self-healing materials being studied, with minor emphasis given to composite properties. The purpose of this review is to assess the self-healing ability of these materials when utilized in fiber reinforced composites

  9. Mechanical Properties of Continuous Fiber Reinforced Zirconium Diboride Matrix Composites

    NASA Technical Reports Server (NTRS)

    Stuffle, Kevin; Creegan, Peter; Nowell, Steven; Bull, Jeffrey D.; Rasky, Daniel J. (Technical Monitor)

    1995-01-01

    Continuous fiber reinforced zirconium diboride matrix composites, SCS-9a-(RBSiCZrB2)matrix, are being developed for leading edge, rocket nozzle and turbine engine applications. Recently, the composite materials have been characterized for tensile properties to 1250 C, the highest temperature tested. The tensile properties are fiber dominated as the matrix is microcracked on fabrication, but favorable failure characteristic are observed. Compression and shear mechanical testing results will be reported if completed. The effects of fiber volume fraction and matrix density on mechanical properties will be discussed. The target applications of the materials will be discussed. Specific testing being performed towards qualification for these applications will be included.

  10. 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.

  11. Thermoforming continuous fiber-reinforced thermoplastic composites

    SciTech Connect

    Wu, Xiang.

    1990-01-01

    In this research the forming process was first decomposed into basic deformation elements with simple geometries, and models were then developed for these elements. A series-parallel model was developed for predicting the upper and lower bounds of composite shear modulus at forming temperature based on the fiber content, fiber distribution, and matrix shear modulus. A shear-flexure model was proposed to describe the initial load-deflection behavior of thermoplastic composites in bending. A ply buckling model was developed which included the contributions from both a surface tension term and a ply buckling term.

  12. Esthetic considerations when splinting with fiber-reinforced composites.

    PubMed

    Strassler, Howard E; Serio, Cheryl L

    2007-04-01

    The primary reasons for splinting and stabilizing teeth are to connect them for the purpose of replacing missing teeth or as an adjunct to periodontal therapy. Although the restorations must be planned to withstand the functional requirements of occlusion and mastication, esthetic considerations must also be taken into account. The challenge in creating an esthetic result with fiber-reinforced composite splints is that there is limited space in the connector region to create the three-dimensional effect required to give teeth the appearance of individuality. Careful planning in the diagnosis and treatment of the fiber splint is essential to allow for adequate tooth preparation to give the illusion of nonsplinted teeth. When missing teeth are replaced with a fiber-reinforced, direct, fixed partial denture, the pontic must be created to achieve an esthetically pleasing result.

  13. Process for the fabrication of ceramic fiber reinforced titanium aluminide

    SciTech Connect

    Horsfall, I.; Cundy, S.J.

    1992-10-01

    This paper describes initial work on a novel process for the production of titanium aluminide matrix composites reinforced with short alumina fibers. The processing route involves an adaption of existing metal matrix composite (MMC) fabrication technology used to produce hybrid particulate/short fiber composites. A preform is produced which contains alumina fibers and titanium metal powder with a fiber content of around 10 percent by volume and approximately 50 percent porosity. This preform is then infiltrated with pure aluminum by a squeeze casting process to produce a fully dense composite of titanium powder and alumina fibers in a metallic aluminum matrix. The composite is then heat treated in a hot isostatic press to react the aluminum and titanium to produce a titanium aluminide matrix. 9 refs.

  14. Creep behavior of tungsten fiber reinforced niobium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grobstein, T. L.

    1989-01-01

    Tungsten fiber reinforced niobium metal matrix composites were evaluated for use in space nuclear power conversion systems. The composite panels were fabricated using the arc-spray monotape technique at the NASA Lewis Research Center. The creep behavior of W/Nb composite material was determined at 1400 and 1500 K in vacuum over a wide range of applied loads. The time to reach 1 percent strain, the time to rupture, and the minimum creep rate were measured. The W/Nb composites exceeded the properties of monolithic niobium alloys significantly even when compared on a strength to density basis. The effect of fiber orientation on the creep strength also was evaluated. Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending on the fiber orientation relative to the stress axis. A relationship was found between the fiber orientation and the creep strength.

  15. Active vibration control of a smart pultruded fiber-reinforced polymer I-beam

    NASA Astrophysics Data System (ADS)

    Song, G.; Qiao, P.; Sethi, V.; Prasad, A.

    2004-08-01

    Advanced and innovative materials and structures are increasingly used in civil infrastructure applications. By combining the advantages of composites and smart sensors and actuators, active or smart composite structures can be created and be efficiently adopted in practical structural applications. This paper presents results on active vibration control of pultruded fiber-reinforced polymer (FRP) composite thin-walled I-beams using smart sensors and actuators. The FRP I-beams are made of E-glass fibers and polyester resins. The FRP I-beam is in a cantilevered configuration. The PZT (lead zirconate titanate) type of piezoelectric ceramic patches are used as smart sensors and actuators. These patches are surface bonded near the cantilevered end of the I-beam. Utilizing results from modal analyses and experimental modal testing, several active vibration control methods, such as position feedback control, strain rate feedback control and lead compensation, are investigated. Experimental results demonstrate that the proposed methods achieve effective vibration control of FRP I-beams. For instance, the modal damping ratio of the strong direction first bending mode increases by more than 1000% with positive position feedback control.

  16. Active vibration control of a smart pultruded fiber-reinforced polymer I-beam

    NASA Astrophysics Data System (ADS)

    Song, Gangbing; Qiao, Pizhong; Sethi, Vineet; Prasad, A.

    2002-06-01

    Advanced and innovative materials and structures are increasingly used in civil infrastructure applications. By combining the advantages of composites and smart sensors and actuators, active or smart composite structures can be created and be efficiently adopted in practical structural applications. This paper presents results of active vibration control of a pultruded fiber-reinforced polymer (FRP) composites thin-walled I-beams using smart sensors and actuators. The FRP I-beams are made of E-glass fibers and polyester resins. The FRP I-beam is in a cantilevered configuration. PZT (Lead zirconate titanate) type of piezoelectric ceramic patches are used as smart sensors and actuators. These patches are surface-bonded near the cantilevered end of the I-beam. Utilizing results from modal analyses and experimental modal testing, several active vibration control methods, such as position feedback control, strain rate feedback control and lead compensator, are investigated. Experimental results demonstrate that the proposed methods achieve effective vibration control of FRP I-beams. For instance, the modal damping ratio of the strong direction first bending mode increases by more than 1000 percent with a positive position feedback control.

  17. Structural mass irregularities and fiber volume influence on morphology and mechanical properties of unsaturated polyester resin in matrix composites

    PubMed Central

    Ahmed, Khalil; Nasir, Muhammad; Fatima, Nasreen; Khan, Khalid M.; Zahra, Durey N.

    2014-01-01

    This paper presents the comparative results of a current study on unsaturated polyester resin (UPR) matrix composites processed by filament winding method, with cotton spun yarn of different mass irregularities and two different volume fractions. Physical and mechanical properties were measured, namely ultimate stress, stiffness, elongation%. The mechanical properties of the composites increased significantly with the increase in the fiber volume fraction in agreement with the Counto model. Mass irregularities in the yarn structure were quantitatively measured and visualized by scanning electron microscopy (SEM). Mass irregularities cause marked decrease in relative strength about 25% and 33% which increases with fiber volume fraction. Ultimate stress and stiffness increases with fiber volume fraction and is always higher for yarn with less mass irregularities. PMID:26644920

  18. Thermomechanical fatigue cracking in fiber reinforced metal-matrix composites

    NASA Astrophysics Data System (ADS)

    Bao, G.; McMeeking, R. M.

    1995-09-01

    A theoretical model is developed for thermomechanical fatigue cracking in fiber reinforced metal-matrix composites. Interfacial debonding is assumed to occur readily, allowing fibers to slide relative to the matrix resisted by a uniform shear stress. The fibers therefore bridge any matrix crack which develops. The crack bridging traction law is obtained, including the effect of thermal expansion mismatch between the fiber and the matrix and a temperature dependence of the frictional shear stress. Any combination of thermal and mechanical cycling is considered as long as the slip zone along the fiber increases in length monotonically during each increment of cycling. However, for clarity, the results are presented in terms of in-phase and out-of-phase cycling of the thermal and mechanical loads at the same frequency. For each case, the stress distributions in the bridging zone as well as the stress intensity factors at the crack tip are computed for relevant regimes of the thermal and mechanical loading conditions. Predictions are made of the matrix fatigue crack growth under combined thermal and mechanical loading conditions. It is found that when the thermal expansion coefficient of the fiber is less than that of the matrix, a significant increase in the crack growth rate results in out-of-phase thermomechanical fatigue. On the other hand, there is decreased tendency for fibers to fail in this case. For in-phase thermomechanical fatigue, the crack growth rate is reduced but the stress in the fiber is larger than that due to mechanical loading alone, resulting in an increased tendency for fiber failure. The implications for life prediction for fiber reinforced metal-matrix composites are discussed.

  19. Making Glass-Fiber-Reinforced Coolant Tubes

    NASA Technical Reports Server (NTRS)

    Curtin, F.

    1985-01-01

    New use found for heat-shrinkable sleeves. Smooth, noncontaminating channels for transporting cooling water in Space Shuttle Extravehicularmobility unit made of fiberglass tubing with aid of heat-shrinkable sleeves. Previously, glass fibers from inner walls of tubes contaminate water.

  20. Micromechanical model of crack growth in fiber reinforced brittle materials

    NASA Technical Reports Server (NTRS)

    Rubinstein, Asher A.; Xu, Kang

    1990-01-01

    A model based on the micromechanical mechanism of crack growth resistance in fiber reinforced ceramics is presented. The formulation of the model is based on a small scale geometry of a macrocrack with a bridging zone, the process zone, which governs the resistance mechanism. The effect of high toughness of the fibers in retardation of the crack advance, and the significance of the fiber pullout mechanism on the crack growth resistance, are reflected in this model. The model allows one to address issues such as influence of fiber spacing, fiber flexibility, and fiber matrix friction. Two approaches were used. One represents the fracture initiation and concentrated on the development of the first microcracks between fibers. An exact closed form solution was obtained for this case. The second case deals with the development of an array of microcracks between fibers forming the bridging zone. An implicit exact solution is formed for this case. In both cases, a discrete fiber distribution is incorporated into the solution.

  1. Hybrid fiber-reinforcement in mortar and concrete

    NASA Astrophysics Data System (ADS)

    Lawler, John Steven

    Performance of concrete and mortar is improved through use of discontinuous fibers because of the resulting fundamental changes in the failure mechanism. The role a specific type of fiber plays in this process is governed by the material and geometry of the fibers, the fiber-matrix bond and the matrix properties. Blending fiber types exhibiting complementary and additive properties in the composite is a means for maximizing the potential of fibers for the reinforcement of concrete. The specific blend pursued in this investigation is a combination of steel or PVA microfibers, that interact with developing cracks, and steel macrofibers, which become crucial once cracks develop. The objective of this investigation is to explore the mechanisms by which fibers interact with the composite matrix and to provide a rigorous characterization of performance achievable with hybrid reinforced concrete. The role of micro- and macrofibers in the failure of mortar is examined using Subregion Scanning Computer Vision. The fracture process occurs in three stages: microcrack formation, microcrack coalescence and finally the formation of macrocracks. Closely spaced microfibers bridge coalesced microcracks. This increases performance up to and around the peak load by delaying the initiation of macrocracking. Once macrocracks develop, macrofibers are most effective at imparting ductility to the composite. Hybrid reinforcing fibers reduce the water permeability of cracked mortar, which has implications for durability, through the induction of multiple cracking. An innovative method for measuring cracked permeability in uniaxial tension under load is presented. The workability of macro- and microfiber hybrids in concrete is governed by the high surface area of the microfibers. A mix design procedure is presented to determine the optimum paste volume to efficiently achieve the best flow and cohesion properties. The relationships between workability, fiber dispersion, and mechanical

  2. 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.

  3. 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.

  4. Material and Flexural Properties of Fiber-reinforced Rubber Concrete

    NASA Astrophysics Data System (ADS)

    Helminger, Nicholas P.

    The purpose of this research is to determine the material properties of rubber concrete with the addition of fibers, and to determine optimal mixture dosages of rubber and fiber in concrete for structural applications. Fiber-reinforced concrete and rubberized concrete have been researched separately extensively, but this research intends to combine both rubber and fiber in a concrete matrix in order to create a composite material, fiber-reinforced rubber concrete (FRRC). Sustainability has long been important in engineering design, but much of the previous research performed on sustainable concrete does not result in a material that can be used for practical purposes. While still achieving a material that can be used for structural applications, economical considerations were given when choosing the proportions and types of constituents in the concrete mix. Concrete mixtures were designed, placed, and tested in accordance with common procedures and standards, with an emphasis on practicality. Properties that were investigated include compressive strength, tensile strength, modulus of elasticity, toughness, and ductility. The basis for determining the optimal concrete mixture is one that is economical, practical, and exhibits ductile properties with a significant strength. Results show that increasing percentages of rubber tend to decrease workability, unit weight, compressive strength, split tensile strength, and modulus of elasticity while the toughness is increased. The addition of steel needle fibers to rubber concrete increases unit weight, compressive strength, split tensile strength, modulus of elasticity, toughness, and ductility of the composite material.

  5. 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.

  6. Short fiber-reinforced cementitious composites manufactured by extrusion technology

    NASA Astrophysics Data System (ADS)

    Mu, Bin

    The use of short fibers in the cement-based composites is more preferable due to the simplicity and economic nature in fabrication. The short fiber-reinforced cementitious composite (SFRCC) manufactured by the extrusion method show a great improvement in both strength and toughness as compared to the fiber-reinforced composites made by traditional casting methods. This improvement can be attributed to the achievement of low porosity and good interfacial bond in SFRCC under high shear and compressive stress during the extrusion process. In the present study, products of cylinders, sheets, pipes and honeycomb panels incorporating various mineral admixtures such as slag, silica fume, and metakaolin have been manufactured by the extrusion technology. Two kinds of short fibers, ductile polyvinyl alcohol (PVA) fibers and stronger but less ductile glass fibers, were used as the reinforcement in the products. After the specimens were extruded, tension, bending and impact tests were performed to study the mechanical properties of these products. The rheology test was performed for each mix to determine its viscoelastic properties. In addition, X-ray diffraction (XRD) and scanning electronic microscopy (SEM) technology were employed to get an insight view of the mechanism. A freezing and thawing experiment (ASTM C666) was also carried to investigate the durability of the specimens. Based on these experimental results, the reinforcing behaviors of these two short fibers were investigated. The enhancing effects of silica fume and metakaolin on the extrudates were compared and discussed. Finally, the optimum amount of silica fume and slag was proposed. Since the key point for a successful extrusion is the properly designed rheology which controls both internal and external flow properties of extrudate, a nonlinear viscoelastic model was applied to investigate the rheological behavior of a movable fresh cementitious composite in an extruder channel. The velocity profile of the

  7. Ageing characteristics of aluminium alloy aluminosilicate discontinuous fiber reinforced composites

    SciTech Connect

    Nath, D.; Singh, V.

    1999-03-05

    Development of continuous fiber reinforced metal matrix composites is aimed at providing high specific strength and stiffness needed for aerospace and some critical high temperature structural applications. Considerable efforts have been made, during the last decade, to improve the strength of age-hardening aluminium alloy matrix composites by suitable heat treatment. It has also been well established that age-hardenable aluminium alloy composites show accelerated ageing behavior because of enhanced dislocation density at the fiber/matrix interface resulting from thermal expansion mismatch between ceramic fiber and the metal matrix. The accelerated ageing of aluminium alloy composites either from dislocation density or the residual stress, as a result of thermal expansion mismatch is dependent on the size of whisker and particulate. Investigations have also been made on the effect of volume fraction of particulate on the ageing behavior of aluminium alloys. The present investigation is concerned with characterization of age-hardening behavior of an Al-Si-Cu-Mg(AA 336) alloy alumino-silicate discontinuous fiber-reinforced composites (referred to as aluminium MMCs in the present text) being developed for automotive pistons. An effort is made to study the effect of volume fraction of the reinforcement on age-hardening behavior of this composite.

  8. 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.

  9. Shock compression behavior of a S2-glass fiber reinforced polymer composite

    NASA Astrophysics Data System (ADS)

    Tsai, Liren; Yuan, Fuping; Prakash, Vikas; Dandekar, Dattatraya P.

    2009-05-01

    Synthetic heterogeneous material systems, e.g., layered composite materials with organic matrices reinforced by glass fibers (GRP), are attractive materials for a variety of lightweight armor applications. However, while the dynamic response of homogeneous materials, such as, metals and ceramics, has been well documented, the ballistic response of heterogeneous material systems is poorly understood. In the present study, in an attempt to better understand the shock-induced compression response of GRPs, a series of plate impact experiments were conducted on a S2-glas fiber reinforced polymer composite comprising S2-glass woven roving in a Cycom 4102 polyester resin matrix. The plate-impact experiments were conducted using an 82.5 mm bore single-stage gas-gun at the Case Western Reserve University. The history of the shock-induced free-surface particle velocity at the rear surface of the target plate was monitored using the multibeam VALYN™ VISAR system. The results of the experiments indicate the absence of an elastic front in the shock-induced free-surface particle velocity profile in the GRP. Moreover, in the low impact velocity range, relatively weak late-time oscillations are observed in the particle velocity profiles. Increasing the amplitude of the shock-induced compression resulted in a decrease in the rise-time of the shock wave front. The critical shock stress amplitude at which a clear shock-front is seen to develop during the shock loading was determined to be between 1.5 and 2.0 GPa. The results of the experiments are used to obtain the equation of state of the GRP in the stress range 0.04-20 GPa. Moreover, the Hugoniot curve (Hugoniot stress versus Hugoniot strain) was calculated using the Rankine-Hugoniot relationships; the departure of the Hugoniot stress versus the particle velocity curve from linearity allowed the estimation of the Hugoniot elastic limit of the GRP to be about 1.6 GPa.

  10. Creep behavior of tungsten fiber reinforced niobium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grobstein, Toni L.

    1992-01-01

    Tungsten fiber reinforced niobium metal matrix composites were evaluated for use in space nuclear power conversion systems. The composite panels were fabricated using the arc-spray monotape technique at the NASA Lewis Research Center. The creep behavior of W/Nb composite material was determined at 1400 and 1500 K in vacuum over a wide range of applied loads. The time to reach 1 percent strain, the time to rupture, and the minimum creep rate were measured. The W/Nb composites exceeded the properties of monolithic niobium alloys significantly even when compared creep strength also was evaluated. Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending the fiber orientation relative to the stress axis. A relationship was found between the fiber orientation and the creep strength.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. High strain-rate model for fiber-reinforced composites

    SciTech Connect

    Aidun, J.B.; Addessio, F.L.

    1995-07-01

    Numerical simulations of dynamic uniaxial strain loading of fiber-reinforced composites are presented that illustrate the wide range of deformation mechanisms that can be captured using a micromechanics-based homogenization technique as the material model in existing continuum mechanics computer programs. Enhancements to the material model incorporate high strain-rate plastic response, elastic nonlinearity, and rate-dependent strength degradation due to material damage, fiber debonding, and delamination. These make the model relevant to designing composite structural components for crash safety, armor, and munitions applications.

  16. Fabrication Routes for Continuous Fiber-Reinforced Ceramic Composites (CFCC)

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A.; Bansal, Narottam P.

    1998-01-01

    The primary approaches used for fabrication of continuous fiber-reinforced ceramic composite (CFCC) components have been reviewed. The CFCC fabrication issues related to fiber, interface, and matrix have been analyzed. The capabilities, advantages and limitations of the five matrix-infiltration routes have been compared and discussed. Today, the best fabrication route for the CFCC end-user is not clear and compromises need to be made depending on the details of the CFCC application. However, with time, this problem should be reduced as research continues to develop advanced CFCC constituents and fabrication routes.

  17. Fabrication Routes for Continuous Fiber-Reinforced Ceramic Composites (CFCC)

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A.; Bansal, Narottam P.

    1998-01-01

    The primary approaches used for fabrication of continuous fiber-reinforced ceramic composite (CFCC) components have been reviewed. The CFCC fabrication issues related to fiber, interface, and matrix have been analyzed. The capabilities. advantages and limitations of the five matrix-infiltration routes have been compared and discussed. Today. the best fabrication route for the CFCC end-user is not clear and compromises need to be made depending on the details of the CFCC application. However, with time, this problem should be reduced as research continues to develop advanced CFCC constituents and fabrication routes.

  18. Fiber reinforced composites in prosthodontics – A systematic review

    PubMed Central

    Nayar, Sanjna; Ganesh, R.; Santhosh, S.

    2015-01-01

    Fiber-reinforced composite (FRC), prostheses offer the potential advantages of optimized esthetics, low wear of the opposing dentition and the ability to bond the prosthesis to the abutment teeth, thereby compensating for less-than-optimal abutment tooth retention and resistance form. These prostheses are composed of two types of composite materials: Fiber-composites to build the substructure and hybrid or micro fill particulate composites to create the external veneer surface. This article reviews the various types of FRCs and its mechanical properties. PMID:26015717

  19. 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.

  20. Carbon fiber reinforced root canal posts. Mechanical and cytotoxic properties.

    PubMed

    Torbjörner, A; Karlsson, S; Syverud, M; Hensten-Pettersen, A

    1996-01-01

    The aim of this study was to compare the mechanical properties of a prefabricated root canal post made of carbon fiber reinforced composites (CFRC) with metal posts and to assess the cytotoxic effects elicited. Flexural modulus and ultimate flexural strength was determined by 3 point loading after CRFC posts had been stored either dry or in water. The bending test was carried out with and without preceding thermocycling of the CFRC posts. The cytotoxicity was evaluated by an agar overlay method after dry and wet storage. The values of flexural modulus and ultimate flexural strength were for dry stored CFRC post 82 +/- 6 GPa and 1154 +/- 65 MPa respectively. The flexural values decreased significantly after water storage and after thermocycling. No cytotoxic effects were observed adjacent to any CFRC post. Although fiber reinforced composites may have the potential to replace metals in many clinical situations, additional research is needed to ensure a satisfying life-span.

  1. Simulations of Fiber Distribution Effects in Fiber-Reinforced Cement Composites

    SciTech Connect

    Bolander, John E.; Lim, Yun Mook

    2008-02-15

    This paper describes a lattice model for coupled moisture transport/stress analyses of fiber-reinforced cement composites (FRCC). Each fiber, and its interface with the matrix material, is explicitly represented within the three-dimensional material volume. This enables the direct study of fiber orientation and distribution effects on composite performance. Realistic, nonuniform fiber distributions can be specified as model input. Basic applications of the model are presented, with emphasis toward simulating the durability mechanics of FRCC exposed to drying environments. The modeling of functionally graded FRCC is an obvious potential extension of this work.

  2. Simulations of Fiber Distribution Effects in Fiber-Reinforced Cement Composites

    NASA Astrophysics Data System (ADS)

    Bolander, John E.; Lim, Yun Mook

    2008-02-01

    This paper describes a lattice model for coupled moisture transport/stress analyses of fiber-reinforced cement composites (FRCC). Each fiber, and its interface with the matrix material, is explicitly represented within the three-dimensional material volume. This enables the direct study of fiber orientation and distribution effects on composite performance. Realistic, nonuniform fiber distributions can be specified as model input. Basic applications of the model are presented, with emphasis toward simulating the durability mechanics of FRCC exposed to drying environments. The modeling of functionally graded FRCC is an obvious potential extension of this work.

  3. 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.

  4. 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

  5. Fabrication of fiber-reinforced composites by chemical vapor infiltration

    SciTech Connect

    Besmann, T.M.; Stinton, D.P.; Matlin, W.M.; Liaw, P.K.

    1996-08-01

    Processing equipment for the infiltration of fiber-reinforced composite tubes is being designed that incorporates improvements over the equipment used to infiltrate disks. A computer-controlled machine-man interface is being developed to allow for total control of all processing variables. Additionally, several improvements are being made to the furnace that will reduce the complexity and cost of the process. These improvements include the incorporation of free standing preforms, cast mandrels, and simpler graphite heating elements.

  6. Rate dependent constitutive models for fiber reinforced polymer composites

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.

    1990-01-01

    A literature survey was conducted to assess the state-of-the-art in rate dependent constitutive models for continuous fiber reinforced polymer matrix composite (PMC) materials. Several recent models which include formulations for describing plasticity, viscoelasticity, viscoplasticity, and rate-dependent phenomenon such as creep and stress relaxation are outlined and compared. When appropriate, these comparisons include brief descriptions of the mathematical formulations, the test procedures required for generating material constants, and details of available data comparing test results to analytical predictions.

  7. Fabrication of fiber-reinforced composites by chemical vapor infiltration

    SciTech Connect

    Besmann, T.M.; Matlin, W.M.; Stinton, D.P.; Liaw, P.K.

    1996-06-01

    Processing equipment for the infiltration of fiber-reinforced composite tubes is being designed that incorporates improvements over the equipment used to infiltrate disks. A computer-controlled machine-man interface is being developed to allow for total control of all processing variables. Additionally, several improvements are being made to the furnace that will reduce the complexity and cost of the process. These improvements include the incorporation of free standing preforms, cast mandrels, and simpler graphite heating elements.

  8. Durability of Cement Composites Reinforced with Sisal Fiber

    NASA Astrophysics Data System (ADS)

    Wei, Jianqiang

    This dissertation focuses mainly on investigating the aging mechanisms and degradation kinetics of sisal fiber, as well as the approaches to mitigate its degradation in the matrix of cement composites. In contrast to previous works reported in the literature, a novel approach is proposed in this study to directly determine the fiber's degradation rate by separately studying the composition changes, mechanical and physical properties of the embedded sisal fibers. Cement hydration is presented to be a crucial factor in understanding fiber degradation behavior. The degradation mechanisms of natural fiber consist of mineralization of cell walls, alkali hydrolysis of lignin and hemicellulose, as well as the cellulose decomposition which includes stripping of cellulose microfibrils and alkaline hydrolysis of amorphous regions in cellulose chains. Two mineralization mechanisms, CH-mineralization and self-mineralization, are proposed. The degradation kinetics of sisal fiber in the cement matrix are also analyzed and a model to predict the degradation rate of cellulose for natural fiber embedded in cement is outlined. The results indicate that the time needed to completely degrade the cellulose in the matrix with cement replacement by 30wt.% metakaolin is 13 times longer than that in pure cement. A novel and scientific method is presented to determine accelerated aging conditions, and to evaluating sisal fiber's degradation rate and durability of natural fiber-reinforced cement composites. Among the static aggressive environments, the most effective approach for accelerating the degradation of natural fiber in cement composites is to soak the samples or change the humidity at 70 °C and higher temperature. However, the dynamic wetting and drying cycling treatment has a more accelerating effect on the alkali hydrolysis of fiber's amorphous components evidenced by the highest crystallinity indices, minimum content of holocellulose, and lowest tensile strength. Based on the

  9. Investigation of rectangular concrete columns reinforced or prestressed with fiber reinforced polymer (FRP) bars or tendons

    NASA Astrophysics Data System (ADS)

    Choo, Ching Chiaw

    Fiber reinforced polymer (FRP) composites have been increasingly used in concrete construction. This research focused on the behavior of concrete columns reinforced with FRP bars, or prestressed with FRP tendons. The methodology was based the ultimate strength approach where stress and strain compatibility conditions and material constitutive laws were applied. Axial strength-moment (P-M) interaction relations of reinforced or prestressed concrete columns with FRP, a linearly-elastic material, were examined. The analytical results identified the possibility of premature compression and/or brittle-tension failure occurring in FRP reinforced and prestressed concrete columns where sudden and explosive type failures were expected. These failures were related to the rupture of FRP rebars or tendons in compression and/or in tension prior to concrete reaching its ultimate strain and strength. The study also concluded that brittle-tension failure was more likely to occur due to the low ultimate tensile strain of FRP bars or tendons as compared to steel. In addition, the failures were more prevalent when long term effects such as creep and shrinkage of concrete, and creep rupture of FRP were considered. Barring FRP failure, concrete columns reinforced with FRP, in some instances, gained significant moment resistance. As expected the strength interaction of slender steel or FRP reinforced concrete columns were dependent more on column length rather than material differences between steel and FRP. Current ACI minimum reinforcement ratio for steel (rhomin) reinforced concrete columns may not be adequate for use in FRP reinforced concrete columns. Design aids were developed in this study to determine the minimum reinforcement ratio (rhof,min) required for rectangular reinforced concrete columns by averting brittle-tension failure to a failure controlled by concrete crushing which in nature was a less catastrophic and more gradual type failure. The proposed method using rhof

  10. Silicon, iron and titanium doped calcium phosphate-based glass reinforced biodegradable polyester composites as bone analogous materials

    NASA Astrophysics Data System (ADS)

    Shah Mohammadi, Maziar

    Bone defects resulting from disease or traumatic injury is a major health care problem worldwide. Tissue engineering offers an alternative approach to repair and regenerate bone through the use of a cell-scaffold construct. The scaffold should be biodegradable, biocompatible, porous with an open pore structure, and should be able to withstand the applied forces. Phosphate-based glasses (PGs) may be used as reinforcing agents in degradable composites since their degradation can be predicted and controlled through their chemistry. This doctoral dissertation describes the development and evaluation of PGs reinforced biodegradable polyesters for intended applications in bone augmentation and regeneration. This research was divided into three main objectives: 1) Investigating the composition dependent properties of novel PG formulations by doping a sodium-free calcium phosphate-based glass with SiO2, Fe2O3, and TiO2. Accordingly, (50P2 O5-40CaO- xSiO2-(10-x)Fe2O3, where x = 10, 5 and 0 mol.%) and (50P2O5-40CaO-xSiO 2-(10-x)TiO2 where x = 10, 7, 5, 3 and 0 mol.%) formulations were developed and characterised. SiO2 incorporation led to increased solubility, ion release, pH reduction, as well as hydrophilicity, surface energy, and surface polarity. In contrast, doping with Fe2O 3 or TiO2 resulted in more durable glasses, and improved cell attachment and viability. It was hypothesised that the presence of SiO 2 in the TiO2-doped formulations could up-regulate the ionic release from the PG leading to higher alkaline phosphatase activity of MC3T3-E1 cells. 2) Incorporating Si, Fe, and Ti doped PGs as fillers, either as particulates (PGPs) or fibres (PGFs), into biodegradable polyesters (polycaprolactone (PCL) and semi-crystalline and amorphous poly(lactic acid) (PLA and PDLLA)) with the aim of developing degradable bone analogous composites. It was found that PG composition and geometry dictated the weight loss, ionic release, and mechanical properties of the composites. It

  11. Development of Ceramic Fibers for Reinforcement in Composite Materials

    NASA Technical Reports Server (NTRS)

    Gates, L. E.; Lent, W. E.; Teague, W. T.

    1961-01-01

    the. testing apparatus for single fiber tensile strength increased the precision. of tests conducted on nine fibers. The highest mean tensile strength, a value of 295,000 pounds per square inch, was obtained with R-141 fibers. Treatment of R-74 fibers with anhydrous Linde A-1100 silane finish improved its mean fiber tensile strength by 25 percent. The lapse of time after fiber formation had no measurable effect on tensile strength. A static heating test conducted with various high melting fibers indicated that Fiberfrax and R-108 underwent no significant changes in bulk volume or resiliency on exposure to 2750 degrees Fahrenheit (1510 degrees Centigrade) in an oxidizing atmosphere. For fiber-resin composition fabrication, ten fiber materials were selected on the bases of high fiber yield, fusion temperature, and type of composition. Fiberfrax, a commercial ceramic fiber, was included for comparison. A new, more effective method of removing pellets from blown fibers was developed. The de-pelletized fibers were treated with a silane finish and felted into ten-inch diameter felts prior to resin impregnation. Composites containing 30 percent by weight of CTL 91-LD phenolic resin were molded under high pressure from the impregnated felts and post-cured to achieve optimum properties. Flexural strength, flexural modules of elasticity, and punch shear strength tests were conducted on the composite specimens. The highest average flexural strength obtained was 19,958 pounds per square inch with the R-74-fiber-resin composite. This compares very favorably with the military specification of 13,000 pounds per square inch flexural strength for randomly oriented fiber reinforced composites. The highest punch shear strength (11,509 pounds per square inch) was obtained with the R-89 fiber-resin composite. The effects of anhydrous fiber finishes on composite strength were not clearly indicated. Plasma arc tests at a heat flux of 550 British Thermal Units per square foot per second on

  12. Optimization of a Hybrid-Fiber-Reinforced High-Strength Concrete

    NASA Astrophysics Data System (ADS)

    Ferreira, L. E. T.; de Hanai, J. B.; Ferrari, V. J.

    2016-07-01

    The fracture performance of a high-strength concrete reinforced with steel fibers was studied. Tests of notched beams subjected to fracture in the three-point bend configuration were conducted in accordance with RILEM recommendations TC 162-TDF. The R-curve concepts based on load-CMOD responses and the RILEM criteria were used for the performance evaluation of concrete beams reinforced with steel fiber mixtures and loaded up to fracture. Steel fibers of different types (regular and microfibers), in different proportions were employed as the reinforcement. The hybrid-fiber-reinforced concrete demonstrated a superior performance regarding their resistance and toughness properties as a result of interaction between the fibers.

  13. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    NASA Astrophysics Data System (ADS)

    Amir, N.; Othman, W. M. S. W.; Ahmad, F.

    2015-07-01

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

  14. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    SciTech Connect

    Amir, N. Othman, W. M. S. W. Ahmad, F.

    2015-07-22

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

  15. Effect of Plasma and Fiber Position on Flexural Properties of a Polyethylene Fiber-Reinforced Composite.

    PubMed

    Spyrides, Silvana M M; Prado, Maíra do; Simão, Renata Antoun; Bastian, Fernando Luis

    2015-10-01

    The aim of this study was to evaluate the effect of plasma treatment using argon and oxygen gases, combined with fiber position on flexural properties of a fiber-reinforced composite. Eleven groups were evaluated, a non-reinforced control group and 10 groups reinforced with InFibra, a woven polyethylene fiber, varying according to the plasma treatment and fiber position. The samples were prepared using a stainless steel two-piece matrix. The three point bending test was performed in an EMIC testing machine. Flexural strength (FS) and flexural deflection (FD) were calculated from initial (IF) and final (FF) failure. Data were evaluated statistically using Kruskal-Wallis and Mann-Whitney tests (p<0.05). For IF, in all groups with fibers placed on the base, the FS and FD values were significantly higher than those positioned away from the base. The highest value of FS was obtained in the group treated with O 3 min (296.2 MPa) and the highest value of FD was obtained in the group treated with 1 min (0.109 mm). For FF the FS and FD values obtained for the groups with fibers positioned away from the base were similar or higher than those placed on the base. The highest FS value was obtained in the group treated with 1 min (317.5 MPa) and the highest FD value was obtained in the group treated with O 3 min (0.177 mm). Plasma treatment influenced FS and FD. Fiber position and plasma treatment affected the flexural properties of a fiber-reinforced composite.

  16. Flexural analysis of palm fiber reinforced hybrid polymer matrix composite

    NASA Astrophysics Data System (ADS)

    Venkatachalam, G.; Gautham Shankar, A.; Raghav, Dasarath; Santhosh Kiran, R.; Mahesh, Bhargav; Kumar, Krishna

    2015-07-01

    Uncertainty in availability of fossil fuels in the future and global warming increased the need for more environment friendly materials. In this work, an attempt is made to fabricate a hybrid polymer matrix composite. The blend is a mixture of General Purpose Resin and Cashew Nut Shell Liquid, a natural resin extracted from cashew plant. Palm fiber, which has high strength, is used as reinforcement material. The fiber is treated with alkali (NaOH) solution to increase its strength and adhesiveness. Parametric study of flexure strength is carried out by varying alkali concentration, duration of alkali treatment and fiber volume. Taguchi L9 Orthogonal array is followed in the design of experiments procedure for simplification. With the help of ANOVA technique, regression equations are obtained which gives the level of influence of each parameter on the flexure strength of the composite.

  17. 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)

    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.

  18. Flexural strengthening of Reinforced Concrete (RC) Beams Retrofitted with Corrugated Glass Fiber Reinforced Polymer (GFRP) Laminates

    NASA Astrophysics Data System (ADS)

    Aravind, N.; Samanta, Amiya K.; Roy, Dilip Kr. Singha; Thanikal, Joseph V.

    2015-01-01

    Strengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.

  19. Modeling and simulation of continuous fiber-reinforced ceramic composites

    NASA Astrophysics Data System (ADS)

    Bheemreddy, Venkata

    Finite element modeling framework based on cohesive damage modeling, constitutive material behavior using user-material subroutines, and extended finite element method (XFEM), are developed for studying the failure behavior of continuous fiber-reinforced ceramic matrix composites (CFCCs) by the example of a silicon carbide matrix reinforced with silicon carbide fiber (SiC/SiCf) composite. This work deals with developing comprehensive numerical models for three problems: (1) fiber/matrix interface debonding and fiber pull-out, (2) mechanical behavior of a CFCC using a representative volume element (RVE) approach, and (3) microstructure image-based modeling of a CFCC using object oriented finite element analysis (OOF). Load versus displacement behavior during a fiber pull-out event was investigated using a cohesive damage model and an artificial neural network model. Mechanical behavior of a CFCC was investigated using a statistically equivalent RVE. A three-step procedure was developed for generating a randomized fiber distribution. Elastic properties and damage behavior of a CFCC were analyzed using the developed RVE models. Scattering of strength distribution in CFCCs was taken into account using a Weibull probability law. A multi-scale modeling framework was developed for evaluating the fracture behavior of a CFCC as a function of microstructural attributes. A finite element mesh of the microstructure was generated using an OOF tool. XFEM was used to study crack propagation in the microstructure and the fracture behavior was analyzed. The work performed provides a valuable procedure for developing a multi-scale framework for comprehensive damage study of CFCCs.

  20. Cylindrical dielectric elastomer actuators reinforced with inextensible fibers

    NASA Astrophysics Data System (ADS)

    Goulbourne, Nakhiah C. S.

    2006-03-01

    Novel actuator configurations for various applications can be obtained using cylindrical dielectric elastomer actuators. A new configuration for a contractile electro-elastomer is presented here for the first time. A cylindrical or tubular configuration is used to realize simultaneous axial shortening and radial expansion when a voltage is applied across the thickness of the hollow cylinder. In this configuration, the inner and outer surfaces of a cylindrical dielectric elastomer are coated with compliant electrodes. The outer cylindrical surface is then enclosed by a network of helical fibers that are very thin, very flexible and inextensible. Fiber networks or cord families are commonly used in many different materials and for a variety of applications. The primary purpose of these networks is structural, that is to say, for reinforcement. The composite active structure proposed here is reminiscent of the McKibben actuator, a pneumatically actuated cylindrical construct consisting of a flexible rubber bladder sheathed in a fiber network, which garners its impressive contracting force from the inextensible fibers that prevent axial extension when an inflation pressure is applied to the internal bladder [1]. The system is modeled using an electro- elastic formulation derived from the large deformation theory of reinforced cylinders [2]. The model combines Maxwell-Faraday electrostatics and nonlinear elasticity theory [3]. Illustratively, solutions are obtained assuming a Mooney-Rivlin material model for a silicone actuator. The results indicate that the relationship between the axial contraction force and the axial shortening is linear for the voltage range considered. The importance of other system parameters such as the fiber angle and the applied constant pressure is also reported.

  1. 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

  2. Glass fiber reinforced concrete for terrestrial photovoltaic arrays

    NASA Technical Reports Server (NTRS)

    Maxwell, H.

    1979-01-01

    The use of glass-fiber-reinforced concrete (GRC) as a low-cost structural substrate for terrestrial solar cell arrays is discussed. The properties and fabrication of glass-reinforced concrete structures are considered, and a preliminary design for a laminated solar cell assembly built on a GRC substrate is presented. A total cost for such a photovoltaic module, composed of a Korad acrylic plastic film front cover, an aluminum foil back cover, an ethylene/vinyl acetate pottant/adhesive and a cotton fabric electrical isolator in addition to the GRC substrate, of $9.42/sq m is projected, which is less than the $11.00/sq m cost goal set by the Department of Energy. Preliminary evaluations are concluded to have shown the design capabilities and cost effectiveness of GRC; however, its potential for automated mass production has yet to be evaluated.

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

    DOEpatents

    Allais, Arnaud; Hoffmann, Ernst

    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).

  4. Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologi

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologies Project - Preliminary Manufacturing Demonstration Articles for Ares V Payload Shroud Barrel Acreage Structure

  5. Methods for an investigation of the effect of material components on the mechanical characteristics of glass-fiber-reinforced plastics

    NASA Technical Reports Server (NTRS)

    Willax, H. O.

    1980-01-01

    The materials used in the production of glass reinforced plastics are discussed. Specific emphasis is given to matrix polyester materials, the reinforcing glass materials, and aspects of specimen preparation. Various methods of investigation are described, giving attention to optical impregnation and wetting measurements and the gravimetric determination of the angle of contact. Deformation measurements and approaches utilizing a piezoelectric device are also considered.

  6. Defect depth measurement of carbon fiber reinforced polymers by thermography

    NASA Astrophysics Data System (ADS)

    Chen, Terry Y.; Chen, Jian-Lun

    2016-01-01

    Carbon fiber reinforced polymers has been widely used in all kind of the industries. However the internal defects can result in the change of material or mechanical properties, and cause safety problem. In this study, step-heating thermography is employed to measure the time series temperature distribution of composite plate. The principle of heat conduction in a flat plate with defect inside is introduced. A temperature separation criterion to determine the depth of defect inside the specimen is obtained experimentally. Applying this criterion to CFRP specimens with embedded defects, the depth of embedded defect in CFRP can be determined quite well from the time series thermograms obtained experimentally.

  7. Bond strength of glass fiber reinforced plastics (GFRP) grouted anchors

    SciTech Connect

    Bellavance, E.; Xu, H.; Benmokrane, B.

    1995-11-01

    This paper describes the results of laboratory and field pull-out tests on cement grouted glass fiber reinforced plastic (GFRP) anchors. As an alternative for grouted steel anchors, GFRP bars have many advantages over steel tendons, and can avoid corrosion and some difficulties in transportation, handling, and installation. Three types of 36 GFRP anchors and 20 steel anchors installed in three types of host media: steel pipe, concrete block, and rock mass were tested in the laboratory as well as in the field. The bond strength, load carrying capacity, load-displacement behavior, and critical bond length of cement grouted GFRP anchors were examined in comparison with conventional steel anchors.

  8. Real time sensing of structural glass fiber reinforced composites by using embedded PVA - carbon nanotube fibers

    NASA Astrophysics Data System (ADS)

    Alexopoulos, N.; Poulin, P.; Bartholome, C.; Marioli-Riga, Z.

    2010-06-01

    Polyvinyl alcohol - carbon nanotube (PVA-CNT) fibers had been embedded to glass fiber reinforced polymers (GFRP) for the structural health monitoring of the composite material. The addition of the conductive PVA-CNT fiber to the nonconductive GFRP material aimed to enhance its sensing ability by means of the electrical resistance measurement method. The test specimen’s response to mechanical load and the in situ PVA-CNT fiber’s electrical resistance measurements were correlated for sensing and damage monitoring purposes. The embedded PVA-CNT fiber worked as a sensor in GFRP coupons in tensile loadings. Sensing ability of the PVA-CNT fibers was also demonstrated on an integral composite structure. PVA-CNT fiber near the fracture area of the structure recorded very high values when essential damage occurred to the structure. A finite element model of the same structure was developed to predict axial strains at locations of the integral composite structure where the fibers were embedded. The predicted FEA strains were correlated with the experimental measurements from the PVA-CNT fibers. Calculated and experimental values were in good agreement, thus enabling PVA-CNT fibers to be used as strain sensors.

  9. CO2 Laser Cutting of Glass Fiber Reinforce Polymer Composite

    NASA Astrophysics Data System (ADS)

    Fatimah, S.; Ishak, M.; Aqida, S. N.

    2012-09-01

    The lamination, matrix properties, fiber orientation, and relative volume fraction of matrix of polymer structure make this polymer hard to process. The cutting of polymer composite using CO2 laser could involve in producing penetration energy in the process. Identification of the dominant factors that significantly affect the cut quality is important. The objective of this experiment is to evaluate the CO2 spot size of beam cutting for Glass Fiber Reinforce Polymer Composite (GFRP). The focal length selected 9.5mm which gave smallest focus spot size according to the cutting requirements. The effect of the focal length on the cut quality was investigated by monitoring the surface profile and focus spot size. The beam parameter has great effect on both the focused spot size and surface quality.

  10. Electrical Insulation Characteristics of Glass Fiber Reinforced Resins

    SciTech Connect

    Tuncer, Enis; Sauers, Isidor; James, David Randy; Ellis, Alvin R

    2009-01-01

    Non-metallic structural materials that act as an electrical insulation are needed for cryogenic power applications. One of the extensively utilized materials is glass fiber reinforced resins (GFRR) and may also be known as GFRP and FRP. They are created from glass fiber cloth that are impregnated with an epoxy resin under pressure and heat. Although the materials based on GFRR have been employed extensively, reports about their dielectric properties at cryogenic temperatures and larger thicknesses are generally lacking in the literature. Therefore to guide electrical apparatus designers for cryogenic applications, GFRR samples with different thicknesses are tested in a liquid nitrogen bath. Scaling relation between the dielectric breakdown strength and the GFFR thickness is established. Their loss tangents are also reported at various frequencies.

  11. Matrix cracking of fiber-reinforced ceramic composites in shear

    NASA Astrophysics Data System (ADS)

    Rajan, Varun P.; Zok, Frank W.

    2014-12-01

    The mechanics of cracking in fiber-reinforced ceramic matrix composites (CMCs) under general loadings remains incomplete. The present paper addresses one outstanding aspect of this problem: the development of matrix cracks in unidirectional plies under shear loading. To this end, we develop a model based on potential energy differences upstream and downstream of a fully bridged steady-state matrix crack. Through a combination of analytical solutions and finite element simulations of the constituent stresses before and after cracking, we identify the dominant stress components that drive crack growth. We show that, when the axial slip lengths are much larger than the fiber diameter and when interfacial slip precedes cracking, the shear stresses in the constituents are largely unaffected by the presence of the crack; the changes that do occur are confined to a 'core' region within a distance of about one fiber diameter from the crack plane. Instead, the driving force for crack growth derives mainly from the axial stresses-tensile in the fibers and compressive in the matrix-that arise upon cracking. These stresses are well-approximated by solutions based on shear-lag analysis. Combining these solutions with the governing equation for crack growth yields an analytical estimate of the critical shear stress for matrix cracking. An analogous approach is used in deriving the critical stresses needed for matrix cracking under arbitrary in-plane loadings. The applicability of these results to cross-ply CMC laminates is briefly discussed.

  12. Life Cycle Assessment of Carbon Fiber-Reinforced Polymer Composites

    SciTech Connect

    Das, Sujit

    2011-01-01

    Carbon fiber-reinforced polymer matrix composites is gaining momentum with the pressure to lightweight vehicles, however energy-intensity and cost remain some of the major barriers before this material could be used in large-scale automotive applications. A representative automotive part, i.e., a 30.8 kg steel floor pan having a 17% weight reduction potential with stringent cash performance requirements has been considered for the life cycle energy and emissions analysis based on the latest developments occurring in the precursor type (conventional textile-based PAN vs. renewable-based lignin), part manufacturing (conventional SMC vs. P4) and fiber recycling technologies. Carbon fiber production is estimated to be about 14 times more energy-intensive than conventional steel production, however life cycle primary energy use is estimated to be quite similar to the conventional part, i.e., 18,500 MJ/part, especially when considering the uncertainty in LCI data that exists from using numerous sources in the literature. Lignin P4 technology offers the most life cycle energy and CO2 emissions benefits compared to a conventional stamped steel technology. With a 20% reduction in energy use in the lignin conversion to carbon fiber and free availability of lignin as a by-product of ethanol and wood production, a 30% reduction in life cycle energy use could be obtained. A similar level of life cycle energy savings could also be obtained with a higher part weight reduction potential of 43%.

  13. Asymptotic Analysis of Fiber-Reinforced Composites of Hexagonal Structure

    NASA Astrophysics Data System (ADS)

    Kalamkarov, Alexander L.; Andrianov, Igor V.; Pacheco, Pedro M. C. L.; Savi, Marcelo A.; Starushenko, Galina A.

    2016-08-01

    The fiber-reinforced composite materials with periodic cylindrical inclusions of a circular cross-section arranged in a hexagonal array are analyzed. The governing analytical relations of the thermal conductivity problem for such composites are obtained using the asymptotic homogenization method. The lubrication theory is applied for the asymptotic solution of the unit cell problems in the cases of inclusions of large and close to limit diameters, and for inclusions with high conductivity. The lubrication method is further generalized to the cases of finite values of the physical properties of inclusions, as well as for the cases of medium-sized inclusions. The analytical formulas for the effective coefficient of thermal conductivity of the fiber-reinforced composite materials of a hexagonal structure are derived in the cases of small conductivity of inclusions, as well as in the cases of extremely low conductivity of inclusions. The three-phase composite model (TPhM) is applied for solving the unit cell problems in the cases of the inclusions with small diameters, and the asymptotic analysis of the obtained solutions is performed for inclusions of small sizes. The obtained results are analyzed and illustrated graphically, and the limits of their applicability are evaluated. They are compared with the known numerical and asymptotic data in some particular cases, and very good agreement is demonstrated.

  14. Acoustic emission of fire damaged fiber reinforced concrete

    NASA Astrophysics Data System (ADS)

    Mpalaskas, A. C.; Matikas, T. E.; Aggelis, D. G.

    2016-04-01

    The mechanical behavior of a fiber-reinforced concrete after extensive thermal damage is studied in this paper. Undulated steel fibers have been used for reinforcement. After being exposed to direct fire action at the temperature of 850°C, specimens were subjected to bending and compression in order to determine the loss of strength and stiffness in comparison to intact specimens and between the two types. The fire damage was assessed using nondestructive evaluation techniques, specifically ultrasonic pulse velocity (UPV) and acoustic emission (AE). Apart from the strong, well known, correlation of UPV to strength (both bending and compressive), AE parameters based mainly on the frequency and duration of the emitted signals after cracking events showed a similar or, in certain cases, better correlation with the mechanical parameters and temperature. This demonstrates the sensitivity of AE to the fracture incidents which eventually lead to failure of the material and it is encouraging for potential in-situ use of the technique, where it could provide indices with additional characterization capability concerning the mechanical performance of concrete after it subjected to fire.

  15. Stabilized fiber-reinforced pavement base course with recycled aggregate

    NASA Astrophysics Data System (ADS)

    Sobhan, Khaled

    This study evaluates the benefits to be gained by using a composite highway base course material consisting of recycled crushed concrete aggregate, portland cement, fly ash, and a modest amount of reinforcing fibers. The primary objectives of this research were to (a) quantify the improvement that is obtained by adding fibers to a lean concrete composite (made from recycled aggregate and low quantities of Portland cement and/or fly ash), (b) evaluate the mechanical behavior of such a composite base course material under both static and repeated loads, and (c) utilize the laboratory-determined properties with a mechanistic design method to assess the potential advantages. The split tensile strength of a stabilized recycled aggregate base course material was found to be exponentially related to the compacted dry density of the mix. A lean mix containing 4% cement and 4% fly ash (by weight) develops sufficient unconfined compressive, split tensile, and flexural strengths to be used as a high quality stabilized base course. The addition of 4% (by weight) of hooked-end steel fibers significantly enhances the post-peak load-deformation response of the composite in both indirect tension and static flexure. The flexural fatigue behavior of the 4% cement-4% fly ash mix is comparable to all commonly used stabilized materials, including regular concrete; the inclusion of 4% hooked-end fibers to this mix significantly improves its resistance to fatigue failure. The resilient moduli of stabilized recycled aggregate in flexure are comparable to the values obtained for traditional soil-cement mixes. In general, the fibers are effective in retarding the rate of fatigue damage accumulation, which is quantified in terms of a damage index defined by an energy-based approach. The thickness design curves for a stabilized recycled aggregate base course, as developed by using an elastic layer approach, is shown to be in close agreement with a theoretical model (based on Westergaard

  16. Heart Valves from Polyester Fibers vs. Biological Tissue: Comparative Study In Vitro.

    PubMed

    Yousefi, Atieh; Vaesken, Antoine; Amri, Amna; Dasi, Lakshmi Prasad; Heim, Frederic

    2017-02-01

    Transcatheter aortic valve implantation (TAVI) has become a popular alternative technique to surgical valve replacement for critical patients. Biological valve tissue has been used in TAVI procedures for over a decade, with over 100,000 implantations to date. However, with only 6 years follow up, little is known about the long-term durability of biological tissue. Moreover, the high cost of tissue harvesting and chemical treatment procedures favor the development of alternative synthetic valve leaflet materials. Textile polyester is one such material which provides outstanding folding and strength properties combined with proven biocompatibility, and could therefore be considered as a candidate to replace the biological valve leaflets in TAVI procedures. For that purpose, in addition to the mechanical properties, the hemodynamic properties of the synthetic material should be comparable to the properties of biological tissue. An ideal replacement heart valve would provide low static and dynamic regurgitation, ensure laminar flow across the valve, and limit the turbidity of flow downstream of the valve. The purpose of the present work is to compare in vitro the mechanical and hemodynamic performances of textile woven polyester valves with biological ones. Testing results indicate that textile valves trade elasticity for superior mechanical strength, relative to biological tissue. Despite this, the dynamic flexibility of textile valve leaflets strongly resembled what was seen with biological leaflets. Regurgitation, as well as slightly modified turbulent patterns, in textile valves was higher than biological valves due to the increased porosity, but, rapid tissue ingrowth post-implantation would likely mitigate this effect. Together these findings provide additional evidence favoring the use of textile polyester as a synthetic heart valve leaflet material.

  17. Physico-mechanical properties of chemically treated palm and coir fiber reinforced polypropylene composites.

    PubMed

    Haque, Md Mominul; Hasan, Mahbub; Islam, Md Saiful; Ali, Md Ershad

    2009-10-01

    In this work, palm and coir fiber reinforced polypropylene bio-composites were manufactured using a single extruder and injection molding machine. Raw palm and coir were chemically treated with benzene diazonium salt to increase their compatibility with the polypropylene matrix. Both raw and treated palm and coir fiber at five level of fiber loading (15, 20, 25, 30 and 35 wt.%) was utilized during composite manufacturing. Microstructural analysis and mechanical tests were conducted. Comparison has been made between the properties of the palm and coir fiber composites. Treated fiber reinforced specimens yielded better mechanical properties compared to the raw composites, while coir fiber composites had better mechanical properties than palm fiber ones. Based on fiber loading, 30% fiber reinforced composites had the optimum set of mechanical properties.

  18. New generation fiber reinforced polymer composites incorporating carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Soliman, Eslam

    The last five decades observed an increasing use of fiber reinforced polymer (FRP) composites as alternative construction materials for aerospace and infrastructure. The high specific strength of FRP attracted its use as non-corrosive reinforcement. However, FRP materials were characterized with a relatively low ductility and low shear strength compared with steel reinforcement. On the other hand, carbon nanotubes (CNTs) have been introduced in the last decade as a material with minimal defect that is capable of increasing the mechanical properties of polymer matrices. This dissertation reports experimental investigations on the use of multi-walled carbon nanotubes (MWCNTs) to produce a new generation of FRP composites. The experiments showed significant improvements in the flexure properties of the nanocomposite when functionalized MWCNTs were used. In addition, MWCNTs were used to produce FRP composites in order to examine static, dynamic, and creep behavior. The MWCNTs improved the off-axis tension, off-axis flexure, FRP lap shear joint responses. In addition, they reduced the creep of FRP-concrete interface, enhanced the fracture toughness, and altered the impact resistance significantly. In general, the MWCNTs are found to affect the behaviour of the FRP composites when matrix failure dominates the behaviour. The improvement in the mechanical response with the addition of low contents of MWCNTs would benefit many industrial and military applications such as strengthening structures using FRP composites, composite pipelines, aircrafts, and armoured vehicles.

  19. 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.

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

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.

    1990-01-01

    An experimental study was conducted to measure the thermooxidative stability of PMR-15 composites reinforced with various fibers and to observe differences in the way they degrade in air. The fibers studied include 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.

  1. 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.

  2. Oxidation Behavior of Carbon Fiber Reinforced Silicon Carbide Composites

    NASA Technical Reports Server (NTRS)

    Valentin, Victor M.

    1995-01-01

    Carbon fiber reinforced Silicon Carbide (C-SiC) composites offer high strength at high temperatures and good oxidation resistance. However, these composites present some matrix microcracks which allow the path of oxygen to the fiber. The aim of this research was to study the effectiveness of a new Silicon Carbide (SiC) coating developed by DUPONT-LANXIDE to enhance the oxidation resistance of C-SiC composites. A thermogravimetric analysis was used to determine the oxidation rate of the samples at different temperatures and pressures. The Dupont coat proved to be a good protection for the SiC matrix at temperatures lower than 1240 C at low and high pressures. On the other hand, at temperatures above 1340 C the Dupont coat did not seem to give good protection to the composite fiber and matrix. Even though some results of the tests have been discussed, because of time restraints, only a small portion of the desired tests could be completed. Therefore, no major conclusions or results about the effectiveness of the coat are available at this time.

  3. Mechanical Behavior of Electrospun Palmfruit Bunch Reinforced Polylactide Composite Fibers

    NASA Astrophysics Data System (ADS)

    Adeosun, S. O.; Akpan, E. I.; Gbenebor, O. P.; Peter, A. A.; Olaleye, Samuel Adebayo

    2016-01-01

    In this study, the mechanical characteristics of electrospun palm fruit bunch reinforced poly lactic acid (PLA) nanofiber composites using treated and untreated filler was examined. Poly lactic acid-palm fruit bunch-dichloromethane blends were electrospun by varying the concentration of the palm fruit bunch between 0 wt.% and 8 wt.%. A constant voltage of 26 kV was applied, the tip-to-collector distance was maintained at 27.5 cm and PLA-palm fruit bunch-dichloromethane (DCM) concentration of 12.5% (w/v) was used. The results revealed that the presence of untreated palm fruit bunch fillers in the electrospun PLA matrix significantly reduces the average diameters of the fibers, causing the formation of beads. As a result there are reductions in tensile strengths of the fibers. The presence of treated palm fruit bunch fillers in the electrospun PLA matrix increases the average diameters of the fibers with improvements in the mechanical properties. The optimal mechanical responses were obtained at 3 wt.% of the treated palm fruit bunch fillers in the PLA matrix. However, increase in the palm fruit fillers (treated and untreated) in the PLA matrix promoted the formation of beads in the nanofiber composites.

  4. Mechanical Properties of Carbon Fiber-Reinforced Aluminum Manufactured by High-Pressure Die Casting

    NASA Astrophysics Data System (ADS)

    Kachold, Franziska; Singer, Robert

    2016-08-01

    Carbon fiber reinforced aluminum was produced by a specially adapted high-pressure die casting process. The MMC has a fiber volume fraction of 27%. Complete infiltration was achieved by preheating the bidirectional, PAN-based carbon fiber body with IR-emitters to temperatures of around 750 °C. The degradation of the fibers, due to attack of atmospheric oxygen at temperatures above 600 °C, was limited by heating them in argon-rich atmosphere. Additionally, the optimization of heating time and temperature prevented fiber degradation. Only the strength of the outer fibers is reduced by 40% at the most. The fibers in core of fiber body are nearly undamaged. In spite of successful manufacturing, the tensile strength of the MMC is below strength of the matrix material. Also unidirectional MMCs with a fiber volume fraction of 8% produced under the same conditions, lack of the reinforcing effect. Two main reasons for the unsatisfactory mechanical properties were identified: First, the fiber-free matrix, which covers the reinforced core, prevents effective load transfer from the matrix to the fibers. And second, the residual stresses in the fiber-free zones are as high as 100 MPa. This causes premature failure in the matrix. From this, it follows that the local reinforcement of an actual part is limited. The stress distribution caused by residual stresses and by loading needs to be known. In this way, the reinforcing phase can be placed and aligned accordingly. Otherwise delamination and premature failure might occur.

  5. Preparation and characterization of wheat straw fibers for reinforcing application in injection molded thermoplastic composites.

    PubMed

    Panthapulakkal, S; Zereshkian, A; Sain, M

    2006-01-01

    The potential of wheat straw fibers prepared by mechanical and chemical processes as reinforcing additives for thermoplastics was investigated. Fibers prepared by mechanical and chemical processes were characterized with respect to their chemical composition, morphology, and physical, mechanical and thermal properties. Composites of polypropylene filled with 30% wheat straw fibers were prepared and their mechanical properties were also evaluated. The fibers prepared by chemical process exhibited better mechanical, physical and thermal properties. Wheat straw fiber reinforced polypropylene composites exhibited significantly enhanced properties compared to virgin polypropylene. However, the strength properties of the composites were less for chemically prepared fiber filled composites. This was due to the poor dispersion of the fibers under the processing conditions used. These results indicate that wheat straw fibers can be used as potential reinforcing materials for making thermoplastic composites.

  6. State-of-Practice on the Dynamic Response of Structures Strengthened with Fiber Reinforced Polymers (FRPs)

    DTIC Science & Technology

    2015-07-01

    ER D C/ G SL S R- 15 -2 State-of-Practice on the Dynamic Response of Structures Strengthened with Fiber Reinforced Polymers (FRPs) G...Reinforced Polymers (FRPs) Robert D. Moser, C. Kennan Crane, Brian H. Green Geotechnical and Structures Laboratory U.S. Army Engineer Research and...unlimited. Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000 ERDC/GSL SR-15-2 ii Abstract Fiber Reinforced Polymers (FRPs) are

  7. Compression Molding of CFRTP Used with Carbon Fiber Extracted from CFRP Waste

    NASA Astrophysics Data System (ADS)

    Kimura, Teruo; Ino, Haruhiro; Nishida, Yuichi; Aoyama, Naoki; Shibata, Katsuji

    This study investigated a compression molding method of carbon fiber reinforced thermoplastics (CFRTP) made of carbon fiber extracted from CFRP waste. The short carbon fibers were mixed with polyester fibers using a papermaking method to make the preform sheet of compression molding. The waste obtained from a textile water jet loom was used as a matrix material. The setting speed of each fiber during the papermaking process was regulated by using a dispersing agent to obtain the good dispersion of each fiber. Laminated preform sheets combined with polyester fibers and carbon fibers were compressed with heating at 300°C and then the polyester fiber was melted as a matrix material. It was cleared from the experimental results that the mechanical properties of molded CFRTP largely depends on both the fiber dispersion and the content of carbon fiber in the preform.

  8. 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.

  9. Micromechanics Solution for the Elastic Moduli of Fiber-Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Huan, Yu Jia; Yang, Liu; Jin, Yu; Guang, Jia Lian; Ming, Liu

    2014-09-01

    The overall elastic moduli of fiber-reinforced concrete composite materials are investigated by employing the theory of micromechanics. A method based on the Mori-Tanaka theory and triple inhomogeneities is found to provide a sufficiently accurate evaluation of the average elastic properties of fiber-reinforced concrete composite materials. The inhomogeneities of the materials are divided into three groups: a fine aggregate, a coarse aggregate, and fibers (steel or polymer). The elastic moduli of fiber-reinforced concrete composite materials are determined as functions of the physical properties and volume fraction of sand, gravel, fibers (steel or polymer), and cement paste as a matrix. The theoretical results obtained are compared with published experimental data. The parameters affecting the elastic moduli of fiber-reinforced concrete are discussed in detail.

  10. The optimal fiber volume fraction and fiber-matrix property compatibility in fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Pan, Ning

    1992-01-01

    Although the question of minimum or critical fiber volume fraction beyond which a composite can then be strengthened due to addition of fibers has been dealt with by several investigators for both continuous and short fiber composites, a study of maximum or optimal fiber volume fraction at which the composite reaches its highest strength has not been reported yet. The present analysis has investigated this issue for short fiber case based on the well-known shear lag (the elastic stress transfer) theory as the first step. Using the relationships obtained, the minimum spacing between fibers is determined upon which the maximum fiber volume fraction can be calculated, depending on the fiber packing forms within the composites. The effects on the value of this maximum fiber volume fraction due to such factors as fiber and matrix properties, fiber aspect ratio and fiber packing forms are discussed. Furthermore, combined with the previous analysis on the minimum fiber volume fraction, this maximum fiber volume fraction can be used to examine the property compatibility of fiber and matrix in forming a composite. This is deemed to be useful for composite design. Finally some examples are provided to illustrate the results.

  11. Structure and Properties of Short Areca Fiber Reinforced Maize PF Composites

    NASA Astrophysics Data System (ADS)

    Kumar, G. C. Mohan

    2009-05-01

    Mechanical properties of the fibers extracted from the areca are determined and compared with the other known natural fiber coir. Further these Areca fibers were chemically treated and the effect of this treatment on fiber strength is studied. Areca fiber composite laminates were prepared with randomly distributed fibers in Maize stalk fine fiber and Phenol Formaldehyde. Composite laminates were prepared with different proportions of phenol formaldehyde and fibers. Tensile test, moisture absorption test, and biodegradable tests on these laminates were carried out. Properties of these areca-reinforced phenol formaldehyde composite laminates were analyzed and reported.

  12. Experimental study on mixed mode fracture in unidirectional fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Gong, Kezhuang; Li, Zheng; Fu, Bin

    2008-11-01

    Fiber reinforced composites are applied broadly in aeronautic and astronautic fields as a structural material. But the investigation in dynamic fracture behavior of fiber reinforced composite stands in the breach for scientists due to a large number of aircraft disasters. In this paper, the mixed mode fracture problems in fiber reinforced composites under impact are studied. First, based on the theory of the reflective dynamic caustic method for mixed mode fracture, corresponding experiments are carried out to study the dynamic fracture behaviors of unidirectional fiber reinforced composites under two kinds load conditions. By recording and analyzing the shadow spot patterns during the crack propagation process carefully, the dynamic fracture toughness and crack growth velocity of fiber reinforced composites are obtained. Via the observation of the crack growth routes and fracture sections, we further reveal the fracture mechanism of unidirectional fiber reinforced composites. It concludes that opening mode still is the easier fracture type for the pre-crack initiation in fiber reinforced composites, while the interface between fibers and matrix becomes the fatal vulnerability during the crack propagation.

  13. 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.

  14. Durability Studies on Confined Concrete using Fiber Reinforced Polymer

    NASA Astrophysics Data System (ADS)

    Ponmalar, V.; Gettu, R.

    2014-06-01

    In this study, 24 concrete cylinders with a notch at the centre were prepared. Among them six cylinders were wrapped using single and double layers of fiber reinforced polymer; six cylinders were coated with epoxy resin; the remaining cylinders were used as a control. The cylinders were exposed to wet and dry cycling and acid (3 % H2SO4) solution for the period of 120 days. Two different concrete strengths M30 and M50 were considered for the study. It is found that the strength, ductility and failure mode of wrapped cylinders depend on number of layers and the nature of exposure conditions. It was noticed that the damage due to wet and dry cycling and acid attack was severe in control specimen than the epoxy coated and wrapped cylinders.

  15. Fiber-reinforced ceramic composites made by chemical vapor infiltration

    SciTech Connect

    Caputo, A.J.; Lowden, R.A.; Stinton, D.P.

    1985-01-01

    A process was developed for the fabrication of ceramic-fiber-reinforced ceramic-matrix composites by chemical vapor infiltration. The ceramic composites were prepared by making fibrous preforms from multiple layers of SiC cloth and forming the silicon-carbide matrix for each component specimen by infiltrating the fibrous preform by a chemical vapor deposition process. A major goal of the work was achieved when infiltration was accomplished in hours instead of weeks by combining the thermal-gradient and forced-gas-flow techniques. Composites that possessed moderate flexural strength and high strain to failure were produced. In addition, the strength of the composites decreased gradually after the maximum strength was obtained, demonstrating that the composites had the desired high toughness and avoided the typical brittle behavior of monolithic ceramics.

  16. Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

    PubMed

    Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

    2016-12-16

    In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

  17. Glass Fiber Reinforced Metal Pressure Vessel Design Guide

    NASA Technical Reports Server (NTRS)

    Landes, R. E.

    1972-01-01

    The Engineering Guide presents curves and general equations for safelife design of lightweight glass fiber reinforced (GFR) metal pressure vessels operating under anticipated Space Shuttle service conditions. The high composite vessel weight efficiency is shown to be relatively insensitive to shape, providing increased flexibility to designers establishing spacecraft configurations. Spheres, oblate speroids, and cylinders constructed of GFR Inconel X-750, 2219-T62 aluminum, and cryoformed 301 stainless steel are covered; design parameters and performance efficiencies for each configuration are compared at ambient and cryogenic temperature for an operating pressure range of 690 to 2760 N/sq cm (1000 to 4000 psi). Design variables are presented as a function of metal shell operating to sizing (proof) stress ratios for use with fracture mechanics data generated under a separate task of this program.

  18. Robotic inspection of fiber reinforced composites using phased array UT

    NASA Astrophysics Data System (ADS)

    Stetson, Jeffrey T.; De Odorico, Walter

    2014-02-01

    Ultrasound is the current NDE method of choice to inspect large fiber reinforced airframe structures. Over the last 15 years Cartesian based scanning machines using conventional ultrasound techniques have been employed by all airframe OEMs and their top tier suppliers to perform these inspections. Technical advances in both computing power and commercially available, multi-axis robots now facilitate a new generation of scanning machines. These machines use multiple end effector tools taking full advantage of phased array ultrasound technologies yielding substantial improvements in inspection quality and productivity. This paper outlines the general architecture for these new robotic scanning systems as well as details the variety of ultrasonic techniques available for use with them including advances such as wide area phased array scanning and sound field adaptation for non-flat, non-parallel surfaces.

  19. Recognizing defects in carbon-fiber reinforced plastics

    NASA Technical Reports Server (NTRS)

    Schuetze, R.; Hillger, W.

    1982-01-01

    The damage tolerance of structures made of carbon-fiber-reinforced plastic is tested under various loads. Test laminate (73/1/1, 24/9/1, 1465 A) specimens of thickness 1.5-3.2 mm with various defects were subjected to static and dynamic loads. Special attention was given to delamination, and ultrasonic C-scans were made on the specimens. It was shown that cracks from even small defects are detected with great accuracy. The same probes were also X rayed; defects that could not be detected under ordinary X rays were bored and studied under vacuum by a contrast technique. The nondestructive ultrasonic and X ray tests were controlled by partially destructive tests, and good agreement was observed.

  20. Composite structural materials. [fiber reinforced composites for aircraft structures

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberly, S. E.

    1981-01-01

    Physical properties of fiber reinforced composites; structural concepts and analysis; manufacturing; reliability; and life prediction are subjects of research conducted to determine the long term integrity of composite aircraft structures under conditions pertinent to service use. Progress is reported in (1) characterizing homogeneity in composite materials; (2) developing methods for analyzing composite materials; (3) studying fatigue in composite materials; (4) determining the temperature and moisture effects on the mechanical properties of laminates; (5) numerically analyzing moisture effects; (6) numerically analyzing the micromechanics of composite fracture; (7) constructing the 727 elevator attachment rib; (8) developing the L-1011 engine drag strut (CAPCOMP 2 program); (9) analyzing mechanical joints in composites; (10) developing computer software; and (11) processing science and technology, with emphasis on the sailplane project.

  1. Objective Surface Evaluation of Fiber Reinforced Polymer Composites

    NASA Astrophysics Data System (ADS)

    Palmer, Stuart; Hall, Wayne

    2013-08-01

    The mechanical properties of advanced composites are essential for their structural performance, but the surface finish on exterior composite panels is of critical importance for customer satisfaction. This paper describes the application of wavelet texture analysis (WTA) to the task of automatically classifying the surface finish properties of two fiber reinforced polymer (FRP) composite construction types (clear resin and gel-coat) into three quality grades. Samples were imaged and wavelet multi-scale decomposition was used to create a visual texture representation of the sample, capturing image features at different scales and orientations. Principal components analysis was used to reduce the dimensionality of the texture feature vector, permitting successful classification of the samples using only the first principal component. This work extends and further validates the feasibility of this approach as the basis for automated non-contact classification of composite surface finish using image analysis.

  2. An inelastic constitutive equation of fiber reinforced plastic laminates

    SciTech Connect

    Kanagawa, Y.; Murakami, S.; Mizobe, T.

    1998-01-01

    A constitutive model for describing the time-dependent inelastic deformation of unidirectional and symmetric angle-ply CFRP (carbon Fiber Reinforced Plastics) laminates is developed. The kinematic hardening creep law of Malinin and Khadjinsky and the evolution equation of Armstrong and Frederick are extended to describe the creep deformation of initially anisotropic materials. In particular, the evolution equations of the back stresses of the anisotropic material were formulated by introducing a transformed strain tensor, by which the expression of the equivalent strain rate of the anisotropic material has the identical form as that of the isotropic materials. The resulting model is applied to analyze the time-dependent inelastic deformation of symmetric angle-ply laminates. Comparison between the predictions and the experimental observations shows that the present model can describe well the time-dependent inelastic behavior under different loadings.

  3. Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection

    PubMed Central

    Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

    2016-01-01

    In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering. PMID:27999245

  4. Metal-bonded, carbon fiber-reinforced composites

    DOEpatents

    Sastri, Suri A.; Pemsler, J. Paul; Cooke, Richard A.; Litchfield, John K.; Smith, Mark B.

    1996-01-01

    Metal bonded carbon fiber-reinforced composites are disclosed in which the metal and the composite are strongly bound by (1) providing a matrix-depleted zone in the composite of sufficient depth to provide a binding site for the metal to be bonded and then (2) infiltrating the metal into the matrix-free zone to fill a substantial portion of the zone and also provide a surface layer of metal, thereby forming a strong bond between the composite and the metal. The invention also includes the metal-bound composite itself, as well as the provision of a coating over the metal for high-temperature performance or for joining to other such composites or to other substrates.

  5. Metal-bonded, carbon fiber-reinforced composites

    DOEpatents

    Sastri, S.A.; Pemsler, J.P.; Cooke, R.A.; Litchfield, J.K.; Smith, M.B.

    1996-03-05

    Metal bonded carbon fiber-reinforced composites are disclosed in which the metal and the composite are strongly bound by (1) providing a matrix-depleted zone in the composite of sufficient depth to provide a binding site for the metal to be bonded and then (2) infiltrating the metal into the matrix-free zone to fill a substantial portion of the zone and also provide a surface layer of metal, thereby forming a strong bond between the composite and the metal. The invention also includes the metal-bound composite itself, as well as the provision of a coating over the metal for high-temperature performance or for joining to other such composites or to other substrates. 2 figs.

  6. Characterization of Nylon 6 Nano Fiber/E-Glass Fiber Reinforced Epoxy Composites

    NASA Astrophysics Data System (ADS)

    Vinod Kumar, T.; Chandrasekaran, M.; Santhanam, V.; Udayakumar, N.

    2017-03-01

    In the paper thermoplastic polymer Nylon-6 is generated in the form of Nanofibers by using an electro spinning method, and concentration of a solution is 4% as a constant then, by varying the process parameters such as flow rate (0.8 ml/hr, 1ml/hr and 1.2 ml/hr) of the solution. The results indicated Nanofibers with 4% concentration and 1 ml/hr produced optimum fibers due to continuous fiber formation. Composites Plates are fabricated by using a Hand lay-up method with different volume fraction (0.5, 1, 2 % v/v) of Nanofibers ratio. Then, the optimum Nanofibers volume ratio (2 % v/v) is reinforced with E-glass fibers and epoxy resin as a matrix. In order to find Nanofibers effect, Mechanical properties like (Tensile, Flexural and Impact) is performed and evaluated.

  7. Orientation factor and number of fibers at failure plane in ring-type steel fiber reinforced concrete

    SciTech Connect

    Lee, C.; Kim, H.

    2010-05-15

    Considering the probabilistic distributions of fibers in ring-type steel fiber reinforced concrete, the orientation factor and the number of ring-type steel fibers crossing the failure plane were theoretically derived as a function of fiber geometry, specimen dimensions, and fiber volume fraction. A total number of 24 specimens were tested incorporating different fiber types, specimen geometry, and fiber volume fractions of 0.2% and 0.4%: 5 beams and 5 panels containing straight steel fibers; and 6 beams and 8 panels containing ring-type steel fibers. Measurements were made to assess the number of fibers at fractured surfaces of steel fiber reinforced concrete. The developed theoretical expressions reasonably predicted the orientation factor and the number of ring-type steel fibers at failure plane: the average and the standard deviation for the ratios of the test to theory were 1.03 and 0.26, respectively. Theoretical investigations and comparisons were made for the values of orientation factor and the number of fibers at failure plane for straight steel fibers and ring-type steel fibers.

  8. Shear degradation in fiber reinforced laminates due to matrix damage

    NASA Astrophysics Data System (ADS)

    Salavatian, Mohammedmahdi

    The objective of this study was to develop and implement a shear modulus degradation model to improve the failure analysis of the fiber reinforced composite structures. Matrix damage, involving transverse and shear cracks, is a common failure mode for composite structures, yet little is known concerning their interaction. To understand the material behavior after matrix failure, the nonlinear response of the composite laminate was studied using pressure vessels made from a [+/-o] bias orientation, which tend to exhibit a matrix dominated failure. The result of this work showed laminate matrix hardening in shear and softening in the transverse direction. A modified Iosipescu coupon was proposed to study the evolution of shear and transverse damage and their mutual effects. The proposed method showed good agreement with tubular results and has advantages of simplified specimen fabrication using standard test fixtures. The proposed method was extended by introducing a novel experimental technique to study the shear degradation model under biaxial loading. Experimental results of the transverse modulus reduction were in good agreement with material degradation models, while the predicted shear modulus reduction was higher than experiment. The discrepancy between available models and observations was due to the presence of a traction between the crack surfaces. Accordingly, a closed form solution was proposed for the shear stress-strain field of a cracked laminate by replacing the cracks with cohesive zones. The constitutive equations of the crack laminate were derived including the effects of internal tractions and transverse stress on the shear modulus. The proposed analytical model was shown to be the most comprehensive model for shear modulus degradation reduction of the fiber reinforced laminates. A numerical implementation of the shear degradation model was done using continuum damage mechanics. Through this work it was shown the common assumption of a linear

  9. Dislocation fiber interactions in short fiber reinforced metal matrix composites during creep and during thermal cycling

    SciTech Connect

    Eggeler, G.F.; Earthman, J.C.

    1997-12-22

    Short fiber reinforced metal matrix composites (SFR MMCs) are attractive engineering materials because they exhibit increased strength and wear resistance as compared to the fiber free matrix materials. For example, an aluminum alloy containing 15 volume percent of Al{sub 2}O{sub 3} fibers with average dimensions of 200 {micro}m length and 3 {micro}m diameter exhibits an improved creep strength with respect to the fiber free matrix. In addition to extended periods of isothermal and static creep loading high temperature components are subjected to temperature changes which are associated with thermal stresses. Thermal cycles can be due to start up and shut down events and can also be a consequence of anisothermal operating conditions. In short fiber reinforced aluminum alloys, in the stress and temperature range of interest, dislocation creep governs the deformation behavior of the MMC`s metallic matrix. It is therefore interesting to discuss the role of dislocations during creep and during thermal cycling of SFR MMCs. In the present paper the authors describe some basic dislocation mechanisms near the fiber/matrix-interface (FMI) of SFR MMCs. They first consider dislocation structures which are associated with the processing of SFR MMCs. Then dislocation processes which are associated with (1) static isothermal creep and (2) thermal cycling are discussed. Common and distinct features of the associated dislocation structures in the matrix zone near the FMI are highlighted. The authors then use the insight they have gained to qualitatively understand the role of dislocations in the macroscopic response of a SFR MMC under more complex load profiles.

  10. Abrasive waterjet machining of fiber reinforced composites: A review

    NASA Astrophysics Data System (ADS)

    Kalla, D. K.; Dhanasekaran, P. S.; Zhang, B.; Asmatulu, R.

    2012-04-01

    Machining of fiber reinforced polymer (FRP) composites is a major secondary manufacturing activity in the aircraft and automotive industries. Traditional machining of these composites is difficult due to the high abrasiveness nature of their reinforcing constituents. Almost all the traditional machining processes involve in the dissipation of heat into the workpiece which can be resulted in damage to workpiece and rapid wear of the cutting tool. This serious issue has been overcome by water jetting technologies. Abrasive waterjet machining (AWJM) is a nontraditional method and one of the best options for machining FRPs. This paper presents a review of the ongoing research and development in AWJM of FRPs, with a critical review of the physics of the machining process, surface characterization, modeling and the newer application to the basic research. Variable cutting parameters, limitations and safety aspects of AWJM and the noise related issues due to high flow rate of water jet will be addressed. Further challenges and scope of the future development in AWJM are also presented in detail.

  11. Nondestructive identification of dye mixtures in polyester and cotton fibers using raman spectroscopy and ultraviolet-visible (UV-Vis) microspectrophotometry.

    PubMed

    Was-Gubala, Jolanta; Starczak, Roza

    2015-01-01

    Presented in this paper is an assessment of the applicability of Raman spectroscopy and microspectrophotometry (MSP) in visible and ultraviolet light (UV-Vis) in the examination of textile fibers dyed with mixtures of synthetic dyes. Fragments of single polyester fibers, stained with ternary mixtures of disperse dyes in small mass concentrations, and fragments of single cotton fibers, dyed with binary or ternary mixtures of reactive dyes, were subjected to the study. Three types of excitation sources, 514, 633, and 785 nm, were used during Raman examinations, while the MSP study was conducted in the 200 to 800 nm range. The results indicate that the capabilities for discernment of dye mixtures are similar in the spectroscopic methods that were employed. Both methods have a limited capacity to distinguish slightly dyed polyester fiber; additionally, it was found that Raman spectroscopy enables identification of primarily the major components in dye mixtures. The best results, in terms of the quality of Raman spectra, were obtained using an excitation source from the near infrared. MSP studies led to the conclusion that polyester testing should be carried out in the range above 310 nm, while for cotton fibers there is no limitation or restriction of the applied range. Also, MSP UV-Vis showed limited possibilities for discriminatory analysis of cotton fibers dyed with a mixture of reactive dyes, where the ratio of the concentration of the main dye used in the dyeing process to minor dye was higher than four. The results presented have practical applications in forensic studies, inter alia.

  12. 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.

  13. 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.

  14. 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.

  15. [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.

  16. 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.

  17. Morphological, mechanical properties and biodegradability of biocomposite thermoplastic starch and polycaprolactone reinforced with sisal fibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The incorporation of fibers as reinforcements in polymer composites has increased due to their renewability, low cost and biodegradability. In this study, sisal fibers were added to a polymer matrix of thermoplastic starch and polycaprolactone, both biodegradable polymers. Sisal fibers (5% and 10%) ...

  18. Oxidation of carbon fiber surfaces for use as reinforcement in high-temperature cementitious material systems

    DOEpatents

    Sugama, Toshifumi

    1990-01-01

    The interfacial bond characteristics between carbon fiber and a cement matrix, in high temperature fiber-reinforced cementitious composite systems, can be improved by the oxidative treatment of the fiber surfaces. Compositions and the process for producing the compositions are disclosed.

  19. Oxidation of carbon fiber surfaces for use as reinforcement in high-temperature cementitious material systems

    DOEpatents

    Sugama, Toshifumi.

    1990-05-22

    The interfacial bond characteristics between carbon fiber and a cement matrix, in high temperature fiber-reinforced cementitious composite systems, can be improved by the oxidative treatment of the fiber surfaces. Compositions and the process for producing the compositions are disclosed. 2 figs.

  20. [Study of an optical fiber grating sensor for monitoring corrosion of reinforcing steel].

    PubMed

    Li, Jun; Wu, Jin; Gao, Jun-qi

    2010-01-01

    Based on the principle of the fiber Bragg grating strain sensor as well as the volume expansion of the reinforcing steel due to corrosion, an optical fiber grating sensor for monitoring corrosion of reinforcing steel and the method of temperature compensation were studied in the present paper. The sensor construction is that one Bragg grating is stuck on the inner center of two bars against each other, and the reinforcement volume as well as the diameter will expand due to corrosion. Based upon sensing mechanism, monitoring will be carried out by transforming the diameter increase to the fiber strain, and as a result the degree and rate of reinforcement corrosion can be obtained. The principle of corrosion monitoring is that the strain induced by corrosion and temperature fluctuation is measured by a reinforcing steel fiber grating sensor. At the same time, the strain induced by temperature fluctuation is also measured by an individual stainless fiber grating sensor. Therefore by two independent fiber grating sensors, the volume changed by corrosion can be separated. By the concrete encapsulating and embedding method of FBG corrosion sensor, the degree of corrosion of reinforcing reinforcement will be measured directly, which is not affected by corrosion factors and can be used in the early corrosion monitoring of reinforcement in concrete structures. Finally the relationship between corrosion rate and shift in center wavelength was calibrated by experiment.

  1. Rapid Prototyping of Continuous Fiber Reinforced Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, R.; Green, C.; Phillips, T.; Cipriani, R.; Yarlagadda, S.; Gillespie, J.; Effinger, M.; Cooper, K. C.; Gordon, Gail (Technical Monitor)

    2002-01-01

    For ceramics to be used as structural components in high temperature applications, their fracture toughness is improved by embedding continuous ceramic fibers. Ceramic matrix composite (CMC) materials allow increasing the overall operating temperature, raising the temperature safety margins, avoiding the need for cooling, and improving the damping capacity, while reducing the weight at the same time. They also need to be reliable and available in large quantities as well. In this paper, an innovative rapid prototyping technique to fabricate continuous fiber reinforced ceramic matrix composites is described. The process is simple, robust and will be widely applicable to a number of high temperature material systems. This technique was originally developed at the University of Delaware Center for Composite Materials (UD-CCM) for rapid fabrication of polymer matrix composites by a technique called automated tow placement or ATP. The results of mechanical properties and microstructural characterization are presented, together with examples of complex shapes and parts. It is believed that the process will be able to create complex shaped parts at an order of magnitude lower cost than current CVI and PIP processes.

  2. Unsaturated and Saturated Permeabilities of Fiber Reinforcement: Critics and Suggestions

    NASA Astrophysics Data System (ADS)

    Park, Chung Hae; Krawczak, Patricia

    2015-04-01

    In general, permeability measurement results show a strong scattering according to the measurement method, the type of test fluid and the fluid injection condition, even though permeability is regarded as a unique property of porous medium. In particular, the discrepancy between the unsaturated and saturated permeabilities for the same fabric has been widely reported. In the literature, relative permeability has been adopted to model the unsaturated flow. This approach has some limits in the modeling of double-scale porosity medium. We address this issue of permeability measurement by rigorously examining the mass conservation condition. Finally, we identify that the pressure gradient is non-linear with positive curvature in the unsaturated flow and a misinterpretation of pressure gradient is the main reason for the difference between the saturated and unsaturated permeabilities of the same fiber reinforcement. We propose to use a fixed value of permeability and to modify the mass conservation equation if there are air voids which are entrapped inside the fiber tow. Finally, we also suggest some guidelines and future perspectives to obtain more consistent permeability measurement results.

  3. R&D on glass fiber reinforced epoxy resin composites for superconducting Tokamak.

    PubMed

    Hu, Nannan; Wang, Ke; Ma, Hongming; Pan, Wanjiang; Chen, Qingqing

    2016-01-01

    The glass fiber reinforced epoxy resin composites play an important role in superconducting Tokamak, which are used to insulate the metal components, such as superconducting winding, cooling pipes, metal electrodes and so on. For the components made of metal and glass fiber reinforced epoxy resin composites, thermal shrinkage leads to non-ignorable thermal stress, therefore, much attention should be paid on the thermal shrinkage rate of glass fiber reinforced epoxy resin composites. The structural design of glass fiber reinforced epoxy resin composites should aim at reducing thermal stress. In this paper, the density, glass fiber content and thermal shrinkage rate of five insulation tubes were tested. The testing results will be applied in structural design and mechanical analysis of isolators for superconducting Tokamak.

  4. Light protection of fiber-reinforced strip using aluminum foil for the direct splinting technique.

    PubMed

    Anagnostou, M; Papazoglou, Efstratios; Mountouris, G; Gaintantzopoulou, M

    2006-01-01

    The critical point of the clinical procedure of direct splinting is the placement of the fiber-reinforced strip, which has to be well adapted to tooth surfaces. This article describes the use of aluminum foil to cover and protect the fiber-reinforced strip from light polymerization during the direct splinting technique. The advantage of using aluminum foil is to prevent premature curing of the fiber-reinforced strip, which would necessitate repetition of the procedure. With this technique, the strip is gradually exposed and adapted to the lingual/palatal surfaces of the teeth and light cured, allowing for ample working time.

  5. 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.

  6. Tunable release of multiclass anti-HIV drugs that are water-soluble and loaded at high drug content in polyester blended electrospun fibers

    PubMed Central

    Carson, Daniel; Jiang, Yonghou; Woodrow, Kim

    2015-01-01

    Objectives Sustained release of small molecule hydrophilic drugs at high doses remains difficult to achieve from electrospun fibers and limits their use in clinical applications. Here we investigate tunable release of several water-soluble anti-HIV drugs from electrospun fibers fabricated with blends of two biodegradable polyesters. Methods Drug-loaded fibers were fabricated by electrospinning using ratios of PCL and PLGA. Fiber morphology was imaged using SEM, and DSC was used to measure thermal properties. HPLC was used to measure drug loading and release from fibers. Cytotoxicity and antiviral activity of drug-loaded fibers were measured in an in vitro cell culture assay. Results We show programmable release of hydrophilic antiretroviral drugs loaded up to 40 wt%. Incremental tuning of highly-loaded drug fibers within 24 hours or >30 days was achieved by controlling the ratio of PCL and PLGA. Fiber compositions containing higher PCL content yielded greater burst release whereas fibers with higher PLGA content resulted in greater sustained release kinetics. We also demonstrated that our drug-loaded fibers are safe and can sustain inhibition of HIV in vitro. Conclusions These data suggest that we were able to overcome current limitations associated with sustained release of small hydrophilic drugs at clinically relevant doses. We expect that our system represents an effective strategy to sustain delivery of water-soluble molecules that will benefit a variety of biomedical applications. PMID:26286184

  7. Al2O3/GdAlO3 fiber for dental porcelain reinforcement.

    PubMed

    Medeiros, Igor S; Luz, Luciana A; Yoshimura, Humberto N; Cesar, Paulo F; Hernandes, Antonio C

    2009-10-01

    The aim of this study was to test the hypothesis that the addition of continuous or milled GdAlO3/Al2O3 fibers to a dental porcelain increases its mechanical properties. Porcelain bars without reinforcement (control) were compared to those reinforced with long fibers (30 vol%). Also, disk specimens reinforced with milled fibers were produced by adding 0 (control), 5 or 10 vol% of particles. The reinforcement with continuous fibers resulted in significant increase in the uniaxial flexural strength from 91.5 to 217.4 MPa. The addition of varied amounts of milled fibers to the porcelain did not significantly affect its biaxial flexural strength compared to the control group. SEM analysis showed that the interface between the continuous fiber and the porcelain was free of defects. On the other hand, it was possible to note the presence of cracks surrounding the milled fiber/porcelain interface. In conclusion, the reinforcement of the porcelain with continuous fibers resulted in an efficient mechanism to increase its mechanical properties; however the addition of milled fibers had no significant effect on the material because the porcelain was not able to wet the ceramic particles during the firing cycle.

  8. 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.

  9. CTMP-based cellulose fibers modified with core-shell latex for reinforcing biocomposites.

    PubMed

    Pan, Yuanfeng; Xiao, Huining; Zhao, Yi; Wang, Zhuang

    2013-06-05

    The toughening of cellulose fiber reinforced polypropylene (PP) was performed via adsorbing the cationic latex with core-shell structure onto chemithermomechanical pulp (CTMP) fibers as reinforcements, which is a novel approach for rendering the surface of cellulose fibers elastomeric. The mechanical, morphological and thermal properties of the resulting biocomposites, containing 40% (wt) of the modified fibers, were investigated. The results showed that with the increasing of the latex dosage up to 2% (wt on dry CTMP fibers), the impact, tensile and flexural strengths of the modified CTMP/PP biocomposites were significantly increased. The toughening mechanism was discussed based on the retarding of crack propagation and the promoting of crystallization of PP matrix (as revealed by DSC characterization). The overall performance of the biocomposite demonstrated that cationic latex-modified CTMP fiber is very effective in reinforcing thermoplastic-based biocomposites along with the synergetic effect on enhancing crystallinity of polymer matrix.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  11. Dimensional accuracy and stability of polymethyl methacrylate reinforced with metal wire or with continuous glass fiber.

    PubMed

    Vallittu, P K

    1996-06-01

    The aim of this study was to determine the dimensional accuracy and stability of denture base polymethyl methacrylate (PMMA), which was reinforced in various ways. Autopolymerizing PMMA and heat-cured PMMA were reinforced either with semicircular steel wire or with a prefabricated experimental reinforcement made of continuous E-glass fiber. Control specimens had no reinforcement. The width of each U-shaped test specimen was measured with a digital micrometer under a light microscope immediately after the test specimen was cured and when stored in water for 1, 2, 7, and 14 days. The results revealed that both the type of PMMA and the type of reinforcement affected the dimensional accuracy of the test specimens, especially after 7 and 14 days in water storage (p < 0.001). The greatest dimensional accuracy was found with the unreinforced test specimen made from autopolymerizing PMMA and with test specimens reinforced with the metal wire made from heat-cured PMMA. In terms of the width of the test specimens, the lowest dimensional accuracy was found in unreinforced and glass fiber reinforced specimens made from heat-cured PMMA. Storage in water did not affect the stability of the width (p > 0.1). The results suggest that the polymerization shrinkage of PMMA causes lower dimensional accuracy of the test specimens reinforced with glass fiber. This should be considered when glass-fiber reinforcement is used clinically.

  12. Time Effects on Morphology and Bonding Ability in Mercerized Natural Fibers for Composite Reinforcement

    DTIC Science & Technology

    2011-01-01

    shown the effect of varying alkali concentrations and times during natural fiber mercerization [14]. In one study, jute fibers were treated with...multiple alkali solutions at two different times. The authors reported a 79% increase in modulus in jute fibers [15]. Another group of authors investigated...Studies on jute - reinforced composites, its limitations, and some solutions through chemical modifications of fibers,” Journal of Applied Polymer

  13. Reduced toxicity polyester resins and microvascular pre-preg tapes for advanced composites manufacturing

    NASA Astrophysics Data System (ADS)

    Poillucci, Richard

    Advanced composites manufacturing broadly encapsulates topics ranging from matrix chemistries to automated machines that lay-up fiber-reinforced materials. Environmental regulations are stimulating research to reduce matrix resin formulation toxicity. At present, composites fabricated with polyester resins expose workers to the risk of contact with and inhalation of styrene monomer, which is a potential carcinogen, neurotoxin, and respiratory irritant. The first primary goal of this thesis is to reduce the toxicity associated with polyester resins by: (1) identification of potential monomers to replace styrene, (2) determination of monomer solubility within the polyester, and (3) investigation of approaches to rapidly screen a large resin composition parameter space. Monomers are identified based on their ability to react with polyester and their toxicity as determined by the Globally Harmonized System (GHS) and a green screen method. Solubilities were determined by the Hoftyzer -- Van Krevelen method, Hansen solubility parameter database, and experimental mixing of monomers. A combinatorial microfluidic mixing device is designed and tested to obtain distinct resin compositions from two input chemistries. The push for safer materials is complemented by a thrust for multifunctional composites. The second primary goal of this thesis is to design and implement the manufacture of sacrificial fiber materials suitable for use in automated fiber placement of microvascaular multifunctional composites. Two key advancements are required to achieve this goal: (1) development of a roll-to-roll method to place sacrificial fibers onto carbon fiber pre-preg tape; and (2) demonstration of feasible manufacture of microvascular carbon fiber plates with automated fiber placement. An automated method for placing sacrificial fibers onto carbon fiber tapes is designed and a prototype implemented. Carbon fiber tows with manual placement of sacrificial fibers is implemented within an

  14. Energy absorption at high strain rate of glass fiber reinforced mortars

    NASA Astrophysics Data System (ADS)

    Fenu, Luigi; Forni, Daniele; Cadoni, Ezio

    2015-09-01

    In this paper, the dynamic behaviour of cement mortars reinforced with glass fibers was studied. The influence of the addition of glass fibers on energy absorption and tensile strength at high strain-rate was investigated. Static tests in compression, in tension and in bending were first performed. Dynamic tests by means of a Modified Hopkinson Bar were then carried out in order to investigate how glass fibers affected energy absorption and tensile strength at high strain-rate of the fiber reinforced mortar. The Dynamic Increase Factor (DIF) was finally evaluated.

  15. Laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) by single-mode fiber laser irradiation

    NASA Astrophysics Data System (ADS)

    Niino, Hiroyuki; Kawaguchi, Yoshizo; Sato, Tadatake; Narazaki, Aiko; Kurosaki, Ryozo; Muramatsu, Mayu; Harada, Yoshihisa; Anzai, Kenji; Aoyama, Mitsuaki; Matsushita, Masafumi; Furukawa, Koichi; Nishino, Michiteru; Fujisaki, Akira; Miyato, Taizo; Kayahara, Takashi

    2014-03-01

    We report on the laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) with a cw IR fiber laser (single-mode fiber laser, average power: 350 W). CFRTP is a high strength composite material with a lightweight, and is increasingly being used various applications. A well-defined cutting of CFRTP which were free of debris and thermal-damages around the grooves, were performed by the laser irradiation with a fast beam galvanometer scanning on a multiple-scanpass method.

  16. Failure mode interaction in fiber reinforced laminated composites

    NASA Astrophysics Data System (ADS)

    Prabhakar, Pavana

    A novel computational modeling framework to predict the compressive strength of fiber reinforced polymer matrix composite (FRPC) laminates has been presented. The model development has been motivated by a set of experimental results on the compression response of two different FRPCs. The model accounts for failure mode interaction between kink-banding and interface fracture (or delamination), which are observed in the experimental results. To reduce the size of the computational model, those interfaces that are most susceptible to delamination are first determined through a free-edge stress analysis. Furthermore, 0-axis layers, which are passive in the failure process are represented through an equivalent homogenized model, but the microstructural features of the on-axis layers (zero plies) are retained in the computational model. The predictions of the model matched well with the experimental observations, and they were found to accurately account for failure mechanism interactions. Therefore, this model has the potential to replace the need to carry out large numbers of tests to obtain the compressive strength allowable for FRPC laminates, the latter allowable being an essential element in the design of lightweight FRPC aerostructures. Furthermore, the thesis presents a new computational model to predict fiber/matrix splitting failure, a failure mode that is frequently observed in in-plane tensile failure of FRPC's. By considering a single lamina, this failure mechanism was seamlessly modeled through the development of a continuum-decohesive nite element (CDFE). The CDFE was motivated by the variational multiscale cohesive method (VMCM) presented earlier by Rudraraju et al. (2010) at the University of Michigan. In the CDFE, the transition from a continuum to a non-continuum is modeled directly (physically) without resorting to enrichment of the shape functions of the element. Thus, the CDFE is a natural merger between cohesive elements and continuum elements. The

  17. Electrically controllable twisted-coiled artificial muscle actuators using surface-modified polyester fibers

    NASA Astrophysics Data System (ADS)

    Park, Jungwoo; Yoo, Ji Wang; Seo, Hee Won; Lee, Youngkwan; Suhr, Jonghwan; Moon, Hyungpil; Koo, Ja Choon; Ryeol Choi, Hyouk; Hunt, Robert; Kim, Kwang Jin; Kim, Soo Hyun; Nam, Jae-Do

    2017-03-01

    As a new class of thermally activated actuators based on polymeric fibers, we investigated polyethylene terephthalate (PET) yarns for the development of a twisted-coiled polymer fiber actuator (TCA). The PET yarn TCA exhibited the maximum linear actuation up to 8.9% by external heating at above the glass transition temperature, 160 °C–180 °C. The payload of the actuator was successfully correlated with the preload and training-load conditions by an empirical equation. Furthermore, the PET-based TCA was electrically driven by Joule heating after the PET surface was metallization with silver. For the fast and precise control of PET yarn TCA, electroless silver plating was conducted to form electrical conductive layers on the PET fiber surface. The silver plated PET-based TCA was tested by Joule heating and the tensile actuation was increased up to 12.1% (6 V) due to the enhanced surface hardness and slippage of PET fibers. Overall, silver plating of the polymeric yarn provided a fast actuation speed and enhanced actuation performance of the TCA actuator by Joule heating, providing a great potential for being used in artificial muscle for biomimetic machines including robots, industrial actuators and powered exoskeletons.

  18. The water absorption effect on the hardness of composites polyester

    NASA Astrophysics Data System (ADS)

    Mohammed, A. A.; Issa, T. T.

    2016-04-01

    Unsaturated polyester resin (UPE) was used as the matrix .The iron woven wire and E-glass fiber type (0 - 9°), were used as a reinforcements additives of weight percentage (5, 10, 15) respectively. Samples were prepared by the hand lay-up method for (UPE), (UPE -Fe) and (UPE- Glass). Chemical analysis was used to identify the composition of Fe wire. Water immersing at room temperature for all samples were done at (2, 5, 7, 9, 12) days. Hardness test (Brinell) showed decreasing with increasing in immersion time for (UPE) from (67) HB to (95) HP after adding the reinforcement Fe fibers, with increasing in the water absorbed content especially in the days (2, 5). The water content of absorption was found to be either decreasing or increasing depending on the number of reinforcing layers added.

  19. Strain measurement in concrete structure using distributed fiber optic sensing based on Brillouin scattering with single-mode fibers embedded in glass fiber reinforcing vinyl ester rod and bonded to steel reinforcing bars

    NASA Astrophysics Data System (ADS)

    Chhoa, Cia Y.; Bao, Xiaoyi; Bremner, Theodore W.; Brown, Anthony W.; DeMerchant, Michael D.; Kalamkarov, Alexander L.; Georgiades, Anastasis V.

    2001-08-01

    The strain distribution in a 1.65m long reinforced concrete beam was measured using the distributed fiber optic sensing system developed by Dr. Bao's Fiber Optic Group at the University of New Brunswick (UNB) with center point and two point loading pattern. A spatial resolution of 0.5m was used. Past experience has shown that the bare optical fiber is too fragile to act as a sensor in a reinforced concrete structure. Therefore, in this experiment, two methods of protecting the fibers were incorporated into the concrete beam to increase the fibers' resistance to mechanical damages and prevent chemical reaction from occurring between the fibers and the concrete. The fibers were either embedded in pultruded glass fiber reinforced vinyl ester (GFRP) rods or bonded to the steel reinforcing bars with an epoxy adhesive. The strain at midspan of the beam as measured by the distributed sensing system was compared with the readings of electrical resistance strain (ERS) and mechanical strain (MS) gauges. The experimental results showed that the pultruded GFRP rods effectively protected the fibers, but the strain readings from the GFRP rods did not agree with the strain measurement of the ERS on the steel reinforcing bars due to the possible slippage of the rods in the concrete. However, the fiber bonded to steel reinforcing bars produced more accurate results and confirmed the potential of this technology to accurately measure strain in a reinforced concrete structure. As expected, the fiber with direct contact to the concrete and steel reinforcing bar, can effectively measured the strain under center point or two point loading.

  20. Properties of glass/carbon fiber reinforced epoxy hybrid polymer composites

    NASA Astrophysics Data System (ADS)

    Patel, R. H.; Sevkani, V. R.; Patel, B. R.; Patel, V. B.

    2016-05-01

    Composite Materials are well known for their tailor-made properties. For the fabrication of composites different types of reinforcements are used for different applications. Sometimes for a particular application, one type of reinforcement may not fulfill the requirements. Therefore, more than one type of reinforcements may be used. Thus, the idea of hybrid composites arises. Hybrid composites are made by joining two or more different reinforcements with suitable matrix system. It helps to improve the properties of composite materials. In the present work glass/carbon fiber reinforcement have been used with a matrix triglycidyl ether of tris(m-hydroxy phenyl) phosphate epoxy resin using amine curing agent. Different physical and mechanical properties of the glass, carbon and glass/carbon fiber reinforced polymeric systems have been found out.

  1. Feasibility research report of villa constructed of glass fiber reinforced concrete

    NASA Astrophysics Data System (ADS)

    Li, Shengli; Lu, Yu; Wang, Dongwei

    2011-04-01

    With the development of economy and improvement degree of modernization, the villa project design program tend to focus on the green, high-tech, humanities, and more emphasis on the integrity of space, noble and elegant feeling. Therefore, based on the study of literatures, this paper discussed the present situation and issue and features of Glass Fiber Reinforced Concrete and the feature of assembly house, and confirmed that the villa of assemble house is feasible by built of Glass Fiber Reinforced Concrete.

  2. Mechanical behavior of Fiber Reinforced SiC/RBSN Ceramic Matrix Composites: Theory and Experiment

    DTIC Science & Technology

    1991-01-01

    AD-A235 926 NASA AVSCOM Technical Memorandum 103688 Technical Report 91-C-004 Mechanical Behavior of Fiber Reinforced SiC/RBSN Ceramic Matrix Composites : Theory... CERAMIC MATRIX COMPOSITES : THEORY AND EXPERIMENT Abhisak Chulya* Department of Civil Engineering Cleveland State University Cleveland, Ohio 44115...tough and sufficiently stable continuous fiber- reinforced ceramic matrix composites (CMC) which can survive in oxidizing environ- ments at temperatures

  3. 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.

  4. Graphite fiber reinforced thermoplastic glass matrix composites for use at 1000 F

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Minford, E. J.

    1985-01-01

    The fabrication and properties of the graphite fiber reinforced glass matrix composite system are described. By reinforcing borosilicate glass with graphite fibers it has been possible to develop a composite whose properties can be compared favorably with resin matrix counterparts. Both high elastic modulus and strength can be obtained and maintained to temperatures of approximately 600 C. In addition, composite dimensional stability is superior to resin or metal matrix systems due to the low thermal expansion behavior of the glass matrix.

  5. Guided wave propagation in porous unidirectional carbon fiber reinforced plastic

    NASA Astrophysics Data System (ADS)

    Dobmann, Nicolas; Bach, Martin

    2017-02-01

    Networks of piezoelectric transducers mounted on aircraft structures for Acousto Ultrasonics (AU) purposes are designed to be applied during the service life of the aircraft. The approach to integrate these sensor networks already during the manufacture of carbon fiber reinforced plastic (CFRP) host structures prompts ideas to achieve an additional benefit by their application for cure monitoring, thus extending their use to the manufacturing chain. This benefit could be extended even further if guided waves generated by AU sensor networks could be used for porosity testing extensively applied for CFRP aircraft structures. In light of this, an experimental study was conducted to investigate effects of porosity on the propagation of guided waves in a basic configuration of unidirectional CFRP. Several samples were manufactured at different porosity levels by variation of the processing pressure. Wave fields were acquired using an ultrasonic scanning device. In the present work, phase velocities are chosen as best measurable and quantifiable propagation feature and the approach for the analysis of phase velocities in porosity samples is outlined. First results are presented and discussed regarding the influence of porosity on guided wave phase velocity and basic applicability for porosity testing of aircraft structures.

  6. High-temperature testing of high performance fiber reinforced concrete

    NASA Astrophysics Data System (ADS)

    Fořt, Jan; Vejmelková, Eva; Pavlíková, Milena; Trník, Anton; Čítek, David; Kolísko, Jiří; Černý, Robert; Pavlík, Zbyšek

    2016-06-01

    The effect of high-temperature exposure on properties of High Performance Fiber Reinforced Concrete (HPFRC) is researched in the paper. At first, reference measurements are done on HPFRC samples without high-temperature loading. Then, the HPFRC samples are exposed to the temperatures of 200, 400, 600, 800, and 1000 °C. For the temperature loaded samples, measurement of residual mechanical and basic physical properties is done. Linear thermal expansion coefficient as function of temperature is accessed on the basis of measured thermal strain data. Additionally, simultaneous difference scanning calorimetry (DSC) and thermogravimetry (TG) analysis is performed in order to observe and explain material changes at elevated temperature. It is found that the applied high temperature loading significantly increases material porosity due to the physical, chemical and combined damage of material inner structure, and negatively affects also the mechanical strength. Linear thermal expansion coefficient exhibits significant dependence on temperature and changes of material structure. The obtained data will find use as input material parameters for modelling the damage of HPFRC structures exposed to the fire and high temperature action.

  7. Multisensor monitoring of drilling in advanced fiber-reinforced composites

    NASA Astrophysics Data System (ADS)

    Okafor, Anthony C.; El-Gizawy, A. Sherif; Enemuoh, E. U.

    1997-06-01

    This paper investigates the main effects of drilling parameters (cutting speed, feed rate, tool geometry, and tool material) on cutting force and hole quality during drilling of magnamite graphite fiber reinforced polyether ether ketone (AS4/PEEK) composites. The AS4/PEEK is a one hundred and ninety nine-ply [0 degree(s)/45 degree(s)/90 degree(s)/-45 degree(s)]s laminate composite. Taguchi orthogonal array L9 technique is used to plan a 34 robust experiment. The workpiece is supported on a fixture and mounted on a 3-component piezoelectric transducer Kistler type 9257A model. The response signals (cutting force and acoustic emission) are acquired simultaneously during the drilling experiments. The signals are instantaneously sampled and stored in a pentium computer for later processing. The digitized signals are processed in time domain. Surface profilometer is used to measure the surface roughness of the drilled holes. The optimum drilling condition is determined by meticulous examination of the drilling parameter's main effects. The responses are analyzed based on Taguchi's signal-to-noise ratio as opposed to the measurement data and analysis of variance. The results show that sensor signals, delamination and surface roughness measurements are well correlated with the drilling parameters. Optimum drill tool materials, drill point angle and cutting conditions have been determined.

  8. Thermal diffusivity measurements on porous carbon fiber reinforced polymer tubes

    NASA Astrophysics Data System (ADS)

    Gruber, Jürgen; Gresslehner, Karl Heinz; Mayr, Günther; Hendorfer, Günther

    2017-02-01

    This work presents the application of methods for the determination of the thermal diffusivity well suited for flat bodies adapted to cylindrical bodies. Green's functions were used to get the temperature time history for small and large times, for the approach of intersecting these two straight lines. To verify the theoretical considerations noise free data are generated by finite element simulations. Furthermore effects of inhomogeneous excitation and the anisotropic heat conduction of carbon fiber reinforced polymers were taken into account in these numerical simulations. It could be shown that the intersection of the two straight lines is suitable for the determination of the thermal diffusivity, although the results have to be corrected depending on the ratio of the cylinders inner and outer radii. Inhomogeneous excitation affects the results of this approach as it lead to multidimensional heat flux. However, based on the numerical simulations a range of the azimuthal angle exists, where the thermal diffusivity is nearly independent of the angle. The method to determine the thermal diffusivity for curved geometries by the well suited Thermographic Signal Reconstruction method and taking into account deviations from the slab by a single correction factor has great advantages from an industrial point of view, just like an easy implementation into evaluation software and the Thermographic Signal Reconstruction methods rather short processing time.

  9. On Healable Polymers and Fiber-Reinforced Composites

    NASA Astrophysics Data System (ADS)

    Nielsen, Christian Eric

    Polymeric materials capable of healing damage would be valuable in structural applications where access for repair is limited. Approaches to creating such materials are reviewed, with the present work focusing on polymers with thermally reversible covalent cross-links. These special cross-links are Diels-Alder (DA) adducts, which can be separated and re-formed, enabling healing of mechanical damage at the molecular level. Several DA-based polymers, including 2MEP4FS, are mechanically and thermally characterized. The polymerization reaction of 2MEP4FS is modeled and the number of established DA adducts is associated with the glass transition temperature of the polymer. The models are applied to concentric cylinder rotational measurements of 2MEP4FS prepolymer at room and elevated temperatures to describe the viscosity as a function of time, temperature, and conversion. Mechanical damage including cracks and scratches are imparted in cured polymer samples and subsequently healed. Damage due to high temperature thermal degradation is observed to not be reversible. The ability to repair damage without flowing polymer chains makes DA-based healable polymers particularly well-suited for crack healing. The double cleavage drilled compression (DCDC) fracture test is investigated as a useful method of creating and incrementally growing cracks in a sample. The effect of sample geometry on the fracture behavior is experimentally and computationally studied. Computational and empirical models are developed to estimate critical stress intensity factors from DCDC results. Glass and carbon fiber-reinforced composites are fabricated with 2MEP4FS as the matrix material. A prepreg process is developed that uses temperature to control the polymerization rate of the monomers and produce homogeneous prepolymer for integration with a layer of unidirectional fiber. Multiple prepreg layers are laminated to form multi-layered cross-ply healable composites, which are characterized in

  10. Smart fiber-reinforced polymer rods featuring improved ductility and health monitoring capabilities

    NASA Astrophysics Data System (ADS)

    Belarbi, Abdeldjelil; Watkins, Steve E.; Chandrashekhara, K.; Corra, Josh; Konz, Bethany

    2001-06-01

    The strain-measuring capability of fiber optic strain gages in fiber-reinforced polymer (FRP) rebars was investigated for failure-inducing loads. Fiber optic interferometric sensors were embedded in a pultruded carbon fiber core and then another layer of carbon fibers were filament wound around the core to form a shell. Pultrusion and filament winding techniques protect the fiber optic strain gages from the concrete environment while providing a secure bond to the core and additional ductility to the overall FRP rebar. Tests of coupon FRP rebar and of FRP-rebar-reinforced concrete beams show that the fiber optic strain gages can read internal strain through failure and can duplicate data from conventional linear variable differential transformers and electrical resistance strain gages. Also, the shell of the FRP rebar inside the concrete beams failed before the rebar core providing pseudo-ductility.

  11. Spectroscopic determination of the in-situ composition of epoxy matrices in glass fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Antoon, M. K.; Zehner, B. E.; Koenig, J. L.

    1980-01-01

    Computerized infrared analysis is applied to the characterization of a glass-reinforced crosslinked polyester. The method of factor analysis determines the number of independent components which constitute the polymeric matrix. Subsequently, the spectra of those components are fitted by a least-squares criterion to spectra of the multicomponent matrix, or, if the glass spectrum is included as an additional component, to the spectra of composites. The least-squares coefficients yield the matrix composition in terms of the initial reactant composition and the extent of crosslinking.

  12. 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.

  13. Bond variability of glass-fiber-reinforcing-plastic reinforcement in concrete

    SciTech Connect

    Hanus, J.P.

    1998-12-01

    This report summarizes an experimental program that investigated the bond variability of glass-fiber-reinforced-polymer (GFRP) reinforcement in concrete. The variables in the study were manufacturer (Marshall Industries Composites, Incorporated M1 and Corrosion Proof Products/Hughes Brothers M2), bar size (Number 5 and 6), cover (2 and 3 bar diameters), and embedment length (10 through 47 inch). Tensile tests were also performed on the GFRP rebar for comparison to bond tests that exhibited bar failure. Eighty-four inverted half-beam bond specimens were tested while monitoring load, loaded-end slip, free-end slip, cracking, and acoustic emissions on the embedded bar and concrete. Three to six replicate tests were conducted for each set of variables. The results of each test within a series were examined to investigate the relative variability with respect to the failure types. The M1 rebar was observed to rely primarily on mechanical interlock to develop bond strength. This conclusion was based on investigations of the rebar surface condition, bar deformation geometry, slip curves, AE results, crack patterns and forensic investigations. Additionally, the ultimate loads for the bond tests with the Ml rebar were affected by changes in embedment lengths but did not vary for tests with 2 and 3d(b) cover. Overall, the M1 rebar had coefficients of variation (COV) of 14.3 and 8.9% for bond tests that exhibited bar failure and tensile test bar failures, respectively. The bond tests that failed in concrete splitting had COVs from 5.2 to 5.9%.

  14. 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.

  15. Effects of EB irradiation on stress-strain curves for carbon fiber reinforced composite materials

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Yamada, K.; Mizutani, A.; Uchida, N.; Tanaka, K.; Nishi, Yoshitake

    2004-02-01

    In order to evaluate influence of electron beam (EB) irradiation on elasticity and stress- strain curve of composite materials reinforced by carbon fiber (CF), carbon fiber reinforced polymer (CFRP) and carbon fiber reinforced graphite (C/C) were treated by EB irradiation of 0.3 MGy. Since the EB strengthening was mainly dominated by the ductility enhancements of carbon fiber and matrix of epoxy resin, EB irradiation enlarged fracture stress and enhanced fracture strain of CFRP. Furthermore, EB irradiation slightly enhanced bending elasticity of CFRP and largely enhanced the initial spring constant related to elasticity of C/C coil. Although the elasticity enhancement of carbon fibers did not largely contribute that of CFRP, that of treated graphite matrix in C/C mainly caused the C/C coil elasticity enhancement by EB irradiation. Such a new treatment is a dream-worthy technology for structural materials to be applied in the fields of future engineering.

  16. 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.

  17. Delamination behavior of carbon fiber/epoxy composite laminates with short fiber reinforcement

    SciTech Connect

    Sohn, M.S.; Hu, X.Z. . Dept. of Mechanical and Materials Engineering)

    1994-06-01

    Delamination in laminated materials is one major mode of damage and failure encountered in application. Fracture mechanics is often used to characterize the interlaminar fracture behavior. The interlaminar fracture energies, G[sub I], G[sub II] and G[sub I/II] are the major concerns to characterize the interlaminar toughness of the composite laminates. Typical mode-I fracture is caused by normal tension, and typical mode-II fracture by shear in the direction of crack extension. The objective of the present study is to compare and discuss the mode-I and mode-II interlaminar fracture energies, G[sub I] and G[sub II] of carbon fiber/epoxy composite laminates with and without the reinforcement of short Kevlar fibers (5--7 mm in length) and to identify the microfracture features of the Kevlar fibers under those two delamination modes through SEM observations. Double cantilever beam (DCB) specimens and end notched flexure (ENF) specimens are used for the mode-I and -II delamination experiments.

  18. Enhanced mechanical properties of a novel, injectable, fiber-reinforced brushite cement.

    PubMed

    Maenz, Stefan; Kunisch, Elke; Mühlstädt, Mike; Böhm, Anne; Kopsch, Victoria; Bossert, Jörg; Kinne, Raimund W; Jandt, Klaus D

    2014-11-01

    Injectable, brushite-forming calcium phosphate cements (CPCs) have great potential as bone replacement materials due to enhanced degradability and long-term inclusion in bone remodeling. However, the use of such brushite-forming CPCs in load-bearing areas is limited by their low mechanical strength. One approach to overcome this limitation is the use of reinforcing fibers. Thus, an injectable, biodegradable, brushite-forming CPC based on beta-tricalcium phosphate/phosphoric acid with fiber reinforcement was developed for minimally invasive surgery. The fibers (diameter 25 µm; length 0.25, 1 or 2mm) were extruded from poly(l-lactide-co-glycolide) acid (PLGA) and added to the CPC (2.5, 5 or 7.5% (w/w)). Independent of the fiber content, injectability of the CPC was retained up to a fiber length of 1mm. The addition of all PLGA fiber types increased diametral tensile strength, biaxial flexural strength, and flexural strength by up to 25% (p ≤ 0.05 for the diametral tensile strength for the CPC with 5% (w/w) 1mm fibers and the biaxial flexural strength of the CPC with 5% (w/w) 0.25 mm fibers). In contrast, the work of fracture strongly and significantly increased (p<0.01) by up to 12.5-fold. At constant fiber content, the mechanical properties of the fiber-reinforced CPC were mostly augmented with increasing fiber length. Also, the addition of PLGA fibers to the brushite-forming CPC (up to 7.5% (w/w)) only transiently delayed cell growth and did not decrease cell viability. Fiber reinforcement of CPCs thus augments their mechanical strength while preserving the injectability and biocompatibility required for their application in modern surgery.

  19. 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.

  20. Elasto-plastic analysis of interface layers for fiber reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Doghri, I.; Leckie, F. A.

    1991-01-01

    The mismatch in coefficients of thermal expansion (CTE) of fiber and matrix in metal matrix composites reinforced with ceramic fibers induces high thermal stresses in the matrix. Elasto-plastic analyses - with different degrees of simplification and modelization - show that an interface layer with a sufficiently high CTE can reduce the tensile hoop stress in the matrix substantially.

  1. 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.

  2. Rheological and Mechanical Properties of Silica-Based Bagasse-Fiber-Ash-Reinforced Recycled HDPE Composites

    NASA Astrophysics Data System (ADS)

    Sitticharoen, W.; Chainawakul, A.; Sangkas, T.; Kuntham, Y.

    2016-07-01

    The rheological and mechanical properties of a recycled high-density polyethylene biocomposite with silicabased bagasse fiber ash as a reinforcing filler were investigated. The bagasse fiber ash (BFA) was surface-treated using a silane coupling agent (vinyltrimethoxysilane). Composites with BFA whose particle size was varied in the range of 3 to 25wt.% (37, 53, and 105mm), were prepared and examined.

  3. Fluorescent protein senses and reports mechanical damage in glass-fiber-reinforced polymer composites.

    PubMed

    Makyła, Katarzyna; Müller, Christoph; Lörcher, Samuel; Winkler, Thomas; Nussbaumer, Martin G; Eder, Michaela; Bruns, Nico

    2013-05-21

    Yellow fluorescent protein (YFP) is used as a mechanoresponsive layer at the fiber/resin interface in glass-fiber-reinforced composites. The protein loses its fluorescence when subjected to mechanical stress. Within the material, it reports interfacial shear debonding and barely visible impact damage by a transition from a fluorescent to a non-fluorescent state.

  4. 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.

  5. In situ synthesis of manganese oxides on polyester fiber for formaldehyde decomposition at room temperature

    NASA Astrophysics Data System (ADS)

    Wang, Jinlong; Yunus, Rizwangul; Li, Jinge; Li, Peilin; Zhang, Pengyi; Kim, Jeonghyun

    2015-12-01

    Removal of low-level formaldehyde (HCHO) is of great interest for indoor air quality improvement. Supported materials especially those with low air pressure drop are of necessity for air purification. Manganese oxides (MnOx) was in situ deposited on the surface of fibers of a non-woven fabric made of polyethylene terephthalate (PET). As-synthesized MnOx/PET were characterized by SEM, XRD, TEM, ATR-FTIR and XPS analysis. The growth of MnOx layer on PET is thought to start with partial hydrolysis of PET, followed by surface oxidation by KMnO4 and then surface-deposition of MnOx particles from the bulk phase. The MnOx particles assembled with nanosheets were uniformly coated on the PET fibers. MnOx/PET showed good activity for HCHO decomposition at room temperature which followed the Mars-van Krevelen mechanism. The removal of HCHO was kept over 94% after 10 h continuous reaction under the conditions of inlet HCHO concentration ∼0.6 mg/m3, space velocity ∼17,000 h-1 and relative humidity∼50%. This research provides a facile method to deposit active MnOx onto polymers with low air resistance, and composite MnOx/PET material is promising for indoor air purification.

  6. Fiber structure formation in melt spinning of bio-based aliphatic co-polyesters

    NASA Astrophysics Data System (ADS)

    Qin, Qing; Takarada, Wataru; Kikutani, Takeshi

    2015-05-01

    High-speed melt spinning of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) with the 3-hydroxyhexanoate composition of 5.4 mol% was carried out. Melting temperature of this polymer is 141.5°C. It has been reported that PHBH fibers of good appearance can be prepared through the melt spinning process only when extrusion temperature is lower than the melting temperature of pure PHB (176 °C). The high-speed melt spinning experiment in this study revealed that the crystallization of PHBH proceeded at high take-up velocities even when the extrusion temperature was higher than the melting temperature of PHB. This result is considered to be due to the enhancement of crystallization through the application of high tensile stress to the molten polymer in the spinning line. As-spun fibers showed sufficiently high mechanical properties. On the other hand, crystalline orientation of α-form crystal increased with an increase in the take-up velocity and the existence of a small amount of β-form crystals was detected at high take-up velocities. This is another indication for the occurrence of crystallization under high tensile stress.

  7. Comparative study of nanomaterials for interlaminar reinforcement of fiber-composite panels

    NASA Astrophysics Data System (ADS)

    Chiu, Karen Rachel; Duenas, Terrisa; Dzenis, Yuris; Kaser, Jase; Bakis, Charles E.; Roberts, J. Keith; Carter, Daniel

    2013-04-01

    Carbon-fiber reinforced polymer (CFRP) composites offer benefits of reduced weight and increased specific strength; however, these materials can have relatively weak interlaminar toughness. The first modes of composite material failure often remain undetected, since failure is not always visually apparent on the surface of composite materials. In this study, several nano-sized materials and integration approaches are investigated as nanoreinforcement for composite materials. Performance is characterized by the ability of each nanoreinforced composite type to improve Mode I interlaminar toughness. The nanomaterials include 1) commercially available surface-modified silica nanoparticles and 2) continuous polyacrylonitrile (PAN) nanofibers. Test articles are manufactured using hand-layup vacuum bagging and feature either reinforced unidirectional carbon fiber or woven carbon fiber material and one of two investigated epoxy-based resin systems. The nanosilica particles were integrated into the fiber composite structure by mixing with the resin system prior to layup. The PAN nanofibers were produced by an electrospinning process; these fibers were integrated by either collecting the fibers of various areal densities as respective "nanomats" on an interim substrate for subsequent transfer during layup, or directly electrospun onto dry carbon fiber ply surfaces. Test articles were characterized according to ASTM D5528 for finding Mode I strain energy release rates. Results were compared to baseline coupons to determine fracture toughness performance. Results showed that the nanosilica-reinforced coupons increased an average of 35% and 25% in strain energy release rates for the coupons featuring unidirectional fibers and woven fibers, respectively, as compared to the corresponding baseline, whereas the nanomat-reinforced and directly deposited nanofiber-reinforced composites decreased. Low strain energy release rates for the PAN nanofiber-reinforced coupons is attributed

  8. 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.

  9. Application of ceramic fibers to the manufacture of reinforced metal-matrix composites

    SciTech Connect

    Wielage, B.; Rahm, J.; Steinhaeuser, S.

    1995-12-31

    The application of the thermal spraying process is a new way to produce carbon fiber or Tyranno fiber reinforced aluminum matrix composites. Spreaded fiber rovings are enveloped in the matrix material with wire flame spraying. The advantage of the thermal spraying process is based in the low times for contacting between the fibers and the liquid matrix material. Chemical reactions on the interface fiber/matrix, which are caused by the decreasing of the fiber tensile strength, can be excluded. The thermal sprayed prepregs can be compressed to MMC by hot pressing process. This longfiber reinforced composites are used to increase f.e. casted components of motors. The aim of this research is the estimation of possibilities to applicate the wire flame spray process for prepreg manufacturing.

  10. Tensile strength and its scatter of unidirectional carbon fiber reinforced composites

    SciTech Connect

    Hamada, H.; Oya, N.; Yamashita, K.; Maekawa, Z.I.

    1995-12-31

    0 (along the fiber direction) and 90 degree (transverse to the fiber direction) tension tests of Carbon Fiber Reinforced Plastics (CFRP) using a great number of specimens were conducted. Tensile properties and their scatter were evaluated by means of the data base. Materials used in this study were seven kinds of carbon fibers and three kinds of epoxy resins. Reinforcing fiber and matrix resin properties strongly affected on 0 and 90 degree properties of CFRP respectively. In 0 degree tension tests, fracture mode of specimen vaned in each material, and a relationship between the scatter of strength and the fracture mode existed. From the results of 9 degree tension tests, some differences of interfacial properties between each laminate were` also detected. According to some considerations on fracture mechanism in 0 degree tension test, it was deduced that the fracture mode depended on the balance of fiber, matrix and interface properties.

  11. Using Plasma-Activated High Performance Fibers with Nanocrystalline Structure in Producing New Reinforced Composite Materials

    NASA Astrophysics Data System (ADS)

    Kudinov, V.; Korneeva, N.

    2008-08-01

    A wet-pull-out method for investigation of interaction between the high performance polyethylene (HPPE) fiber and polymer matrix is discussed. The paper concerns a cold plasma technique for improving the bond of the HPPE fibers to the matrices and the fibers impregnation with the matrix. Controlled parameters are pull-out force and the height of the matrix capillary lifting along the fiber both in air and in vacuum, in combination with plasma activation of the fibers. The method allows one to estimate the wetting and impregnation of multi-filament fiber with the matrix and simultaneously measure the joint strength. Coupled action of plasma treatment and vacuum impregnation of the fibers improves the joint strength by a factor of 3. Plasma activated HPPE fibers impregnated in air show the value of shear strength τ of 4 Kg/mm2. To understand the effect of treatment initial and plasma-activated fibers were used to fabricate composite materials (CM). The properties and failure modes were compared to those of CM reinforced with untreated fibers. The failure mode of CM reinforced with plasma-activated fibers points to a high strength of the bond between the fibers and the matrix.

  12. High-frequency components made of carbon-fiber reinforced plastics for satellite payloads

    NASA Astrophysics Data System (ADS)

    Saulich, G.

    1981-06-01

    The design and the material characteristics of carbon-fiber reinforced plastics (CFRP) are discussed, taking into account characteristic data for various types of fibers and details of material construction. Waveguide filters made of carbon-fiber reinforced plastics are considered. These filters are used in satellite transponders in connection with the high resonator quality required. Attention is given to tubes and plates of CFRF, aspects of metallization, and adhesive bonding. Reflector antennas of CFRP are discussed, taking into account the design of CFRP reflectors, the reflection characteristics of CFRP reflectors, CFRP laminate characteristics, reflector coatings, and selection criteria for the design of CFRP reflectors.

  13. Engineering of fiber-reinforced tissues with anisotropic biodegradable nanofibrous scaffolds.

    PubMed

    Nerurkar, Nandan L; Baker, Brendon M; Chen, Chiu-Yu; Elliott, Dawn M; Mauck, Robert L

    2006-01-01

    The repair of dense fiber-reinforced tissues poses a significant challenge for the tissue engineering community. The function of these structures is largely dependent on their architectural form, and as such, scaffold organization is an important design parameter in generating tissue analogues. To address this issue, we have recently utilized electrospinning to instill controllable fiber anisotropy in nanofibrous scaffolds. This abstract details the mechanical characterization of the bulk and local properties of these scaffolds, and points to their potential application in the repair and/or generation of fiber-reinforced tissues that recapitulate the native form.

  14. Research on the melt impregnation of continuous carbon fiber reinforced nylon 66 composites

    NASA Astrophysics Data System (ADS)

    Jia, M. Y.; Li, C. X.; Xue, P.; Chen, K.; Chen, T. H.

    2016-07-01

    Impregnation mold of continuous carbon fiber reinforced thermoplastic composites was designed and built in the article. Based on the theory of fluid mechanics and Darcy's law, a model of the melt impregnation was also established. The influences of fiber bundle width and impregnation pins’ diameter on the impregnation degree were studied by numerical simulation. Continuous carbon fiber reinforced nylon 66 composites were prepared. The effects of coated angle and impregnation mold temperature on the mechanical properties of the composites were also described.The agreement between the experimental data and prediction by the model was found to be satisfactory.

  15. Monitoring ageing of alkali resistant glass fiber reinforced cement (GRC) using guided ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Eiras, J. N.; Amjad, U.; Mahmoudabadi, E.; Payá, J.; Bonilla, M.; Kundu, T.

    2013-04-01

    Glass fiber reinforced cement (GRC) is a Portland cement based composite with alkali resistant (AR) glass fibers. The main drawback of this material is the ageing of the reinforcing fibers with time and especially in presence of humidity in the environment. Until now only destructive methods have been used to evaluate the durability of GRC. In this study ultrasonic guided wave inspection of plate shaped specimens has been carried out. The results obtained here show that acoustic signatures are capable of discerning ageing in GRC. Therefore, the ultrasonic guided wave based inspection technique is a promising method for the nondestructive evaluation of the durability of the GRC.

  16. Study of fracture mechanisms of short fiber reinforced AS composite by acoustic emission technique

    SciTech Connect

    Kida, Sotoaki; Suzuki, Megumu

    1995-11-01

    The fracture mechanisms of short fiber reinforced AS composites are studied by acoustic emission technique for examining the effects of fiber contents. The loads P{sub b} and P{sub c} which the damage mechanisms change are obtained at the inflection points of the total AE energy curve the energy gradient method. The damages are generated by fiber breaking at the load point of P{sub b} and P{sub c} in B material, and by the fiber breaking and the debonding between resin and fiber at the load points of P{sub b} and P{sub c} in C material.

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

    PubMed

    Nagakura, Manamu; Tanimoto, Yasuhiro; Nishiyama, Norihiro

    2017-02-11

    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.

  18. 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.

  19. Mechanical behavior of polyester-based woven jute/glass hybrid composites

    NASA Astrophysics Data System (ADS)

    Ahsan, Q.; Tanju, S.

    2012-06-01

    In polymer composite fabrication system, hybridization of jute fibers with synthetic fibers is one of the techniques adopted to overcome some of the limitations (poor mechanical properties and moisture resistance) that have been identified for jute fiber reinforced composites. In the present study, the effect of hybridization on mechanical properties of jute and glass mat reinforced polyester composites has been evaluated experimentally. The composites were made of glass mat, jute mat and varying layers of jute and glass mat in the polyester matrix by applying hand lay-up technique at room temperature (250C). The values of mechanical properties obtained from tensile, flexural and interlaminar shear strength (ILSS) tests show significant improvement with the increase of glass fiber content in hybrid composites. But the positive contribution from glass mat in increasing of ILSS of composite is limited to some extent and the optimum ILSS is achieved when glass-jute incorporated in composite as 50-50 weight basis. SEM images were used to study the modes of fracture, fiber-matrix adhesion, and jute-glass layer adhesion. The fracture surfaces resulted from different tests clearly show that cracks propagate throughout the polyester matrix by tearing the jute mat and delaminating the glass mat.

  20. Health monitoring of precast bridge deck panels reinforced with glass fiber reinforced polymer bars

    NASA Astrophysics Data System (ADS)

    Ries, James Mcdaniel

    The Beaver Creek Bridge on US highway 6 is the pilot project for Glass Fiber Reinforced Polymer (GFRP) bridge decks and posttensioned bridge decks in the state of Utah. The bridge was built in 2009, using accelerated bridge construction practices, including the use of precast prestressed girders, as well as precast decking. The westbound bridge decking was composed of 12 precast panels each measuring 41'-5" long, 6'-10" wide, and 9¼" thick, and weighing approximately 33 kips. At the time, these panels were the longest GFRP panels in the United States. The Utah Department of Transportation has decided to evaluate GFRP reinforcing bars as an alternative to steel rebar in this bridge deck. The hope is to increase the lifespan of bridge decks to match the service life of the entire bridge. Due to the nature of the GFRP bars, the panels were lifted at four points using straps instead of imbedded anchors. During the four-point lifting, the panels exhibited small deflections and strains; furthermore, no cracks larger than hairline cracks were found in the panels after lifting. The Beaver Creek Bridge deck is the first precast deck in the state of Utah to be posttensioned in the direction of traffic. Posttensioning bridge decks is expected to become the norm in the state of Utah. The posttensioning resulted in increased continuity between panels. In order to quantify the expected performance of the bridge during its service life, a truck load test was performed. The truck load test was comprised of a static and dynamic test. During the truck load test, the bridge experienced deflections in the panels which were 93% below design values. Girder deflections were also small. The use of GFRP bars has the potential to extend the life of bridge decks exposed to deicing salts from 45 years to 100 years, while only requiring an increased capital cost in the bridge of 8%. Furthermore, the use of GFRP bars in conjunction with accelerated building practices has the potential to

  1. Strain-rate dependence of the compressive properties of normal and carbon-fiber-reinforced bone cement.

    PubMed

    Saha, S; Pal, S

    1983-11-01

    Normal and carbon-fiber-reinforced (1 wt. %) bone cement samples were tested in compression at various strain rates. Both the compressive strength and proportional limit increased in general with increasing strain rate. Similar strain-rate sensitivity was also shown by the carbon-fiber-reinforced bone cement. The mechanical properties, namely the modulus of elasticity, the proportional limit, and the compressive strength of the carbon-fiber-reinforced bone cement showed highly significant positive correlations with the strain rate.

  2. 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

  3. LOW-COST COMPOSITES IN VEHICLE MANUFACTURE - Natural-fiber-reinforced polymer composites in automotive applications.

    SciTech Connect

    Holbery, Jim; Houston, Dan

    2006-11-01

    In the last decade, natural fiber composites have experienced rapid growth in the European automotive market, and this trend appears to be global in scale, provided the cost and performance is justified against competing technologies. However, mass reduction, recyclability, and performance requirements can be met today by competing systems such as injection-molded unreinforced thermoplastics; natural fiber composites will continue to expand their role in automotive applications only if such technical challenges as moisture stability, fiber-polymer interface compatibility, and consistent, repeatable fiber sources are available to supply automotive manufacturers. Efforts underway by Tier I and II automotive suppliers to explore hybrid glass-natural fiber systems, as well as applications that exploit such capabilities as natural fiber sound dampening characteristics, could very well have far-reaching effects. In addition, the current development underway of bio-based resins such as Polyhydroxyalkanoate (PHA) biodegradable polyesters and bio-based polyols could provide fully bio-based composite options to future automotive designers. In short, the development of the natural fiber composite market would make a positive impact on farmers and small business owners on a global scale, reduce US reliance on foreign oil, improve environmental quality through the development of a sustainable resource supply chain, and achieve a better CO2 balance over the vehicle?s lifetime with near-zero net greenhouse gas emissions.

  4. Strength of fiber reinforced ceramics on the basis of a micromechanical analysis

    NASA Astrophysics Data System (ADS)

    Rubinstein, Asher A.

    1994-03-01

    A NEW ANALYTICAL approach to the analysis of fiber reinforced brittle matrix composite is presented. The formulated model considers the failure mechanism as a formation of a crack through the matrix with intact fibers bridging the crack surfaces. The analysis accounts for a physical representation of discrete fiber distribution. The developed model is based on an implicit formulation of the exact solution to the corresponding boundary value problem. The composite strength is evaluated by relating the local stress intensity factor acting on an uncracked matrix with the remotely applied uniform stress. The growth of the internal fully bridged crack is followed from a small crack with one fiber bridging zone to an infinite number of fibers bridging the crack surfaces. The results obtained here directly involve fiber spacing, and evaluate the forces acting on each fiber and all fracture controlling parameters, such as all local stress intensity factors acting on the matrix and each fiber within the bridging zone.

  5. Fabrication and biocompatibility of collagen sponge reinforced with poly(glycolic acid) fiber.

    PubMed

    Hiraoka, Yosuke; Kimura, Yu; Ueda, Hiroki; Tabata, Yasuhiko

    2003-12-01

    This article describes an investigation of collagen sponge mechanically reinforced through the incorporation of poly(glycolic acid) (PGA) fiber. A collagen solution with PGA fiber homogeneously dispersed at collagen:PGA weight ratios of 1.5, 0.8, 0.4, and 0.2 was freeze-dried, followed by dehydrothermal cross-linking to obtain collagen sponges incorporating PGA fiber to various extents. By scanning electron microscopy observation, the collagen sponges exhibited isotropic and interconnected pore structures with an average size of 180 microm, irrespective of PGA fiber incorporation. As expected, PGA fiber incorporation enabled the collagen sponges to significantly enhance their compression strength. In vitro cell culture studies revealed that the number of L929 fibroblasts initially attached was significantly greater for any collagen sponge incorporating PGA fiber than for collagen sponge. The shrinkage of sponge after cell seeding was suppressed by fiber incorporation. It is possible that shrinkage suppression results in the superior cell attachment of sponge incorporating PGA fiber. After subcutaneous implantation into the backs of mice, the residual volume of collagen sponge incorporating PGA fiber was significant compared with that of collagen sponge and increased with a decrease in the collagen:PGA ratio. The greater number of cells infiltrated and deeper infiltration were observed for collagen sponge incorporating PGA fiber implanted subcutaneously. We conclude that the incorporation of PGA fiber is a simple and promising way to reinforce collagen sponge without impairing biocompatibility.

  6. Friction and wear behavior of short fiber-reinforced poly(amide-imide) composites

    SciTech Connect

    Lee, K.H.; Youn, J.R. )

    1992-06-01

    Tribological behavior of short fiber-reinforced thermoplastic composites was investigated experimentally and theoretically. Short carbon fiber and glass fiber reinforced poly(amide-imide) composites were tested. Titanium oxide powder-filled composite was also tested for comparison with the fiber composites. Block-on-ring type wear testing was performed for 24 h at three different sliding conditions. Frictional force was measured and stored by a data acquisition system and wear was measured as weight loss after the test. Wear tracks on the specimen and the counterface were examined with an optical microscope to observe fiber damage and formation of wear film. The equivalent stress distribution around each fiber at the sliding surface was calculated by employing a finite element program. The lowest friction and wear was obtained for the carbon fiber composite, the highest friction for the glass fiber composite, and the highest wear for TiO2-filled one. It was observed that the glass fibers are damaged and removed from the surface more easily than the carbon fibers, and the finite element analysis also suggests easier debonding of glass fibers. 23 refs.

  7. A new constitutive theory for fiber-reinforced incompressible nonlinearly elastic solids

    NASA Astrophysics Data System (ADS)

    Horgan, Cornelius O.; Saccomandi, Giuseppe

    2005-09-01

    We consider an incompressible nonlinearly elastic material in which a matrix is reinforced by strong fibers, for example fibers of nylon or carbon aligned in one family of curves in a rubber matrix. Rather than adopting the constraint of fiber inextensibility as has been previously assumed in the literature, here we develop a theory of fiber-reinforced materials based on the less restrictive idea of limiting fiber extensibility. The motivation for such an approach is provided by recent research on limiting chain extensibility models for rubber. Thus the basic idea of the present paper is simple: we adapt the limiting chain extensibility concept to limiting fiber extensibility so that the usual inextensibility constraint traditionally used is replaced by a unilateral constraint. We use a strain-energy density composed with two terms, the first being associated with the isotropic matrix or base material and the second reflecting the transversely isotropic character of the material due to the uniaxial reinforcement introduced by the fibers. We consider a base neo-Hookean model plus a special term that takes into account the limiting extensibility in the fiber direction. Thus our model introduces an additional parameter, namely that associated with limiting extensibility in the fiber direction, over previously investigated models. The aim of this paper is to investigate the mathematical and mechanical feasibility of this new model and to examine the role played by the extensibility parameter. We examine the response of the proposed models in some basic homogeneous deformations and compare this response to those of standard models for fiber reinforced rubber materials. The role of the strain-stiffening of the fibers in the new models is examined. The enhanced stability of the new models is then illustrated by investigation of cavitation instabilities. One of the motivations for the work is to apply the model to the biomechanics of soft tissues and the potential merits

  8. Evaluation of post-fire strength of concrete flexural members reinforced with glass fiber reinforced polymer (GFRP) bars

    NASA Astrophysics Data System (ADS)

    Ellis, Devon S.

    Owing to their corrosion resistance and superior strength to weight ratio, there has been, over the past two decades, increased interest in the use of fiber-reinforced polymer (FRP) reinforcing bars in reinforced concrete structural members. The mechanical behavior of FRP reinforcement differs from that of steel reinforcement. For example, FRP reinforcement exhibit a linear stress-strain behavior until the bar ruptures and the strength, stiffness and bond properties of FRP reinforcement are affected more adversely by elevated temperatures. All structures are subject to the risk of damage by fire and fires continue to be a significant cause of damage to structures. Many structures do not collapse after being exposed to fire. The safety of the structure for any future use is dependent on the ability to accurately estimate the post-fire load capacity of the structure. Assuming that the changes, due to fire exposure, in the mechanical behavior of the GFRP reinforcing bar and concrete, and the bond between the reinforcing bar and the concrete are understood, an analytical procedure for estimating the post-fire strength of GFRP reinforced concrete flexural elements can be developed. This thesis investigates the changes in: a) tensile properties and bond of GFRP bars; and b) the flexural behavior of GFRP reinforced concrete beams flexural after being exposed to elevated temperatures up to 400°C and cooled to ambient temperature. To this end, twelve tensile tests, twelve pullout bond tests and ten four-point beam tests were performed. The data from the tests were used to formulate analytical procedures for evaluating the post-fire strength of GFRP reinforced concrete beams. The procedure produced conservative results when compared with the experimental data. In general, the residual tensile strength and modulus of elasticity of GFRP bars decrease as the exposure temperature increases. The loss in properties is however, smaller than that observed by other researchers when

  9. Fiber Reinforcement in Injection Molded Nylon 6/6 Spur Gears

    NASA Astrophysics Data System (ADS)

    Senthilvelan, S.; Gnanamoorthy, R.

    2006-07-01

    Injection molded polymer composite gears are being used in many power and or motion transmission applications. In order to widen the utilization of reinforced polymers for precision motion transmission and noise less applications, the accuracy of molded gears should be increased. Since the injection molded gear accuracy is significantly influenced by the material shrinkage behaviour, there is a need to understand the influence of fiber orientation and gate location on part shrinkage behaviour and hence the gear accuracy. Unreinforced and 20% short glass fiber reinforced Nylon 6/6 spur gears were injection molded in the laboratory and computer aided simulations of gear manufacturing was also carried out. Results of the mold flow simulation of gear manufacturing were correlated with the actual fiber orientation and measured major geometrical parameters of the molded gears. Actual orientation of the fibers near the tooth profile, weld line region and injection points of molded gears were observed using optical microscope and correlated with predicted fiber orientation.

  10. Development of wind turbine towers using fiber reinforced polymers

    NASA Astrophysics Data System (ADS)

    Ungkurapinan, Nibong

    With an ongoing trend in the wind turbine market, the size of wind turbines has been increasing continuously. Larger wind turbines imply an increase in size, weight, and loads acting on the wind turbine tower. This requires towers to be stronger and stiffer, and consequently leads to bigger tower diameters. Because of their size and weight, transportation and erection require heavy equipment that makes the use of such towers prohibitive in remote communities. To tackle this problem, a research program was initiated at the University of Manitoba to develop the technology required for the fabrication of wind turbine towers constructed of fiber reinforced polymers (FRP) for use in remote communities in Canada. The research program was carried out in stages. During the first stage, a feasibility study and an analytical investigation on various shapes of FRP towers were conducted. The concept of a multi-cellular composite tower was examined in great detail and the finite element results showed that such a tower could result in almost 45 percent reduction in weight. In the second stage of this research program, a robotic filament winding machine was designed and constructed in the Composites Laboratory of the University of Manitoba. It was used to fabricate the multi-cell tower specimens for testing. The third stage of the research program involved the experimental investigation, which was carried out in three phases. In the first phase, two single cell specimens were tested to failure under lateral loading. The specimens were 8 ft (2.44 m) long. The second phase involved the testing of two single cells loaded in compression. The third phase of the experimental investigation involved the testing of two eight-cell jointed tower specimens. The specimens were octagonal and tapered, with a diameter of 21.4 in (543 mm) at the base and 17.4 in (441 mm) at the top. They were 16 ft (4.88 m) in height and tested as cantilever under static loading. Local buckling was the dominant

  11. Development of silicon nitride composites with continuous fiber reinforcement

    SciTech Connect

    Starr, T.L.; Mohr, D.L.; Lackey, W.J.; Hanigofsky, J.A.

    1993-10-01

    The composites were fabricated using ultrafine Si powders prepared by attritor milling; the powders exhibits full conversion to Si nitride in < 3 h at {le} 1200 C (these conditions reduce degradation of the fibers compared to conventional). Effects of processing conditions on fiber properties and the use of fiber coatings to improve stability during processing as well as change the fiber-matrix interfacial properties were investigated. A duplex carbon-silicon carbide coating, deposited by CVD, reduced fiber degradation in processing, and it modified the fiber-matrix adhesion. Si nitride matrix composites were fabricated using reaction sintering, forming laminates, filament-wound plates, and tubes. In each case, an attritor milled Si powder slurry is infiltrated into ceramic fiber preforms or tows, which are then assembled to form a 3-D structure for reaction sintering. The resulting composites have properties comparable to chemical vapor infiltration densified composites, with reasonable strengths and graceful composite fracture behavior.

  12. In Vitro Evaluation of Veneering Composites and Fibers on the Color of Fiber-Reinforced Composite Restorations

    PubMed Central

    Hasani Tabatabaei, Masoomeh; Hasani, Zahra; Ahmadi, Elham

    2014-01-01

    Objective: Color match between fiber-reinforced composite (FRC) restorations and teeth is an imperative factor in esthetic dentistry. The purpose of this study is to evaluate the influence of veneering composites and fibers on the color change of FRC restorations. Materials and Methods: Glass and polyethylene fibers were used to reinforce a direct microhybrid composite (Z250, 3M ESPE) and a microfilled composite (Gradia Indirect, GC). There were eight experimental groups (n=5 disks per group). Four groups were used as the controls (non-FRC control) and the others were used as experimental groups. CIELAB parameters (L*, a* and b*) of specimens were evaluated against a white background using a spectrophotometer to assess the color change. The color difference (ΔE*) and color coordinates were (L*, a* and b*) analyzed by two-way ANOVA and Tukey’s test. Results: Both types of composite and fiber influenced the color parameters (ΔL*, Δa*). The incorporation of fibers into the composite in the experimental groups made them darker than the control groups, except in the Gradia Indirect+ glass fibers group. Δb* is affected by types of fibers only in direct fiber reinforced composite. No statistically significant differences were recognized in ΔE* among the groups (p>0.05). Conclusion: The findings of the present study suggest that the tested FRC restorations exhibited no difference in color in comparison with non-FRC restoration. Hence, the types of veneering composites and fibers did not influence the color change (ΔE*) of FRC restorations. PMID:25584060

  13. Feasibility study of prestressed natural fiber-reinforced polylactic acid (pla) composite materials

    NASA Astrophysics Data System (ADS)

    Hinchcliffe, Sean A.

    The feasibility of manufacturing prestressed natural-fiber reinforced biopolymer composites is demonstrated in this work. The objective of this study was to illustrate that the specific mechanical properties of biopolymers can be enhanced by leveraging a combination of additive manufacturing (3D printing) and post-tensioning of continuous natural fiber reinforcement. Tensile and flexural PLA specimens were 3D-printed with and without post-tensioning ducts. The mechanical properties of reinforcing fibers jute and flax were characterized prior to post-tensioning. The effect of matrix cross-sectional geometry and post-tensioning on the specific mechanical properties of PLA were investigated using mechanical testing. Numerical and analytical models were developed to predict the experimental results, which confirm that 3D-printed matrices improve the specific mechanical properties of PLA composites and are further improved via initial fiber prestressing. The results suggest that both additive manufacturing and fiber prestressing represent viable new methods for improving the mechanical performance of natural fiber-reinforced polymeric composites.

  14. Effects of glass fiber modified with calcium silicate hydrate (C-S-H(I)) reinforced cement

    NASA Astrophysics Data System (ADS)

    Xin, M.; Zhang, L.; Ge, S.; Cheng, X.

    2017-03-01

    In this paper, calcium silicate hydrate (C-S-H(I)) and glass fiber modified with C-S-H(I) (SiF) at ambient temperature were synthesized. SiF and untreated fiber (OF) were incorporated into cement paste. Phase composition of C-S-H(I), SiF and OF was characterized by XRD. The surface morphologies were characterized by SEM. Flexural performance of fiber reinforced cement (FRC) at different curing ages was investigated. Results indicated that both SiF and OF could reinforce cement paste. SiF had a more positive effect on improving the flexural performance of FRC than OF. The strength of SiF reinforced cement was 11.48MPa after 28 days curing when fiber volume was 1.0%, 12.55% higher than that of OF reinforced cement. The flexural strength increased with the addition of fiber volume. However, the large dosage of fiber might cause a decrease in flexural strength of FRC.

  15. Processing and properties of multiscale cellular thermoplastic fiber reinforced composite (CellFRC)

    NASA Astrophysics Data System (ADS)

    Sorrentino, L.; Cafiero, L.; D'Auria, M.; Iannace, S.

    2015-12-01

    High performance fiber reinforced polymer composites are made by embedding high strength/modulus fibers in a polymeric matrix. They are a class of materials that owe its success to the impressive specific mechanical properties with respect to metals. In many weight-sensitive applications, where high mechanical properties and low mass are required, properties per unit of mass are more important than absolute properties and further weight reduction is desirable. A route to reach this goal could be the controlled induction of porosity into the polymeric matrix, while still ensuring load transfer to the reinforcing fibers and fiber protection from the environment. Cellular lightweight fiber reinforced composites (CellFRC) were prepared embedding gas bubbles of controlled size within a high performance thermoplastic matrix reinforced with continuous fibers. Pores were induced after the composite was first saturated with CO2 and then foamed by using an in situ foaming/shaping technology based on compression moulding with adjustable mould cavities. The presence of micro- or submicro-sized cells in the new CellFRC reduced the apparent density of the structure and led to significant improvements of its impact properties. Both structural and functional performances were further improved through the use of a platelet-like nanofiller (Expanded Graphite) dispersed into the matrix.

  16. Fabrication and evaluation of mechanical properties of alkaline treated sisal/hemp fiber reinforced hybrid composite

    NASA Astrophysics Data System (ADS)

    Venkatesha Gupta, N. S.; Akash; Sreenivasa Rao, K. V.; kumar, D. S. Arun

    2016-09-01

    Fiber reinforced polymer composite have acquired a dominant place in variety of applications because of higher specific strength and modulus, the plant based natural fiber are partially replacing currently used synthetic fiber as reinforcement for polymer composites. In this research work going to develop a new material which posses a strength to weight ratio that for exceed any of the present material. The hybrid composite sisal/hemp reinforced with epoxy matrix has been developed by compression moulding technique according to ASTM standards. Sodium hydroxide (NAOH) was used as alkali for treating the fibers. The amount of reinforcement was varied from 10% to 50% in steps of 10%. Prepared specimens were examined for mechanical properties such as tensile strength, flexural strength, and hardness. Hybrid composite with 40wt% sisal/hemp fiber were found to posses higher strength (tensile strength = 53.13Mpa and flexural strength = 82.07Mpa) among the fabricated hybrid composite specimens. Hardness value increases with increasing the fiber volume. Morphological examinations are carried out to analyze the interfacial characteristics, internal structure and fractured surfaces by using scanning electron microscope.

  17. Manufacturing and Mechanical Testing of a New Functionally Graded Fiber Reinforced Cement Composite

    NASA Astrophysics Data System (ADS)

    Shen, Bin; Hubler, Mija; Paulino, Glaucio H.; Struble, Leslie J.

    2008-02-01

    A functionally graded (FG) material system is employed to make fiber use more efficient in a fiber reinforced cement composite (FRCC). This preliminary study demonstrates beam elements that were functionally graded fiber reinforced cement composite (FGFRCC) with four layers, each with a different fiber volume ratio. Fiber volume ratio was graded in accordance with its potential contribution to the mechanical load-bearing capacity so as to reduce the overall fiber volume ratio while preserving the flexural strength and ductility of the beam. Extrusion was used to produce single homogeneous layers of constant fiber volume ratio. The FRCC layers with different fiber volume ratios were stacked according to a desired configuration and then pressed to make an integrated FGFRCC. Flexural tests were carried out to characterize the mechanical behavior, and the results were analyzed to evaluate the effectiveness of the designed fiber distribution. Compared with homogeneous FRCC with the same overall fiber volume fraction, the FGFRCC exhibited about 50% higher strength and comparable ductility.

  18. Manufacturing and Mechanical Testing of a New Functionally Graded Fiber Reinforced Cement Composite

    SciTech Connect

    Shen Bin; Hubler, Mija; Paulino, Glaucio H.; Struble, Leslie J.

    2008-02-15

    A functionally graded (FG) material system is employed to make fiber use more efficient in a fiber reinforced cement composite (FRCC). This preliminary study demonstrates beam elements that were functionally graded fiber reinforced cement composite (FGFRCC) with four layers, each with a different fiber volume ratio. Fiber volume ratio was graded in accordance with its potential contribution to the mechanical load-bearing capacity so as to reduce the overall fiber volume ratio while preserving the flexural strength and ductility of the beam. Extrusion was used to produce single homogeneous layers of constant fiber volume ratio. The FRCC layers with different fiber volume ratios were stacked according to a desired configuration and then pressed to make an integrated FGFRCC. Flexural tests were carried out to characterize the mechanical behavior, and the results were analyzed to evaluate the effectiveness of the designed fiber distribution. Compared with homogeneous FRCC with the same overall fiber volume fraction, the FGFRCC exhibited about 50% higher strength and comparable ductility.

  19. Multi-scale modeling of fiber and fabric reinforced cement based composites

    NASA Astrophysics Data System (ADS)

    Soranakom, Chote

    With an increased use of fiber reinforced concrete in structural applications, proper characterization techniques and development of design guides are needed. This dissertation presents a multi-scale modeling approach for fiber and fabric reinforced cement-based composites. A micromechanics-based model of the yarn pullout mechanism due to the failure of the interfacial zone is presented. The effect of mechanical anchorage of transverse yarns is simulated using nonlinear spring elements. The yarn pullout mechanism was used in a meso-scale modeling approach to simulate the yarn bridging force in the crack evolution process. The tensile stress-strain response of a tension specimen that experiences distributed cracking can be simulated using a generalized finite difference approach. The stiffness degradation, tension stiffening, crack spacing evolution, and crack width characteristics of cement composites can be derived using matrix, interface and fiber properties. The theoretical models developed for fabric reinforced cement composites were then extended to cover other types of fiber reinforced concrete such as shotcrete, glass fiber reinforced concrete (GFRC), steel fiber reinforced concrete (SFRC), ferrocement and other conventional composite systems. The uniaxial tensile stress-strain response was used to formulate a generalized parametric closed-form solution for predicting flexural behavior of various composites at the macro-structural level. The flexural behaviors of these composites were modeled in a unified manner by means of a moment-curvature relationship based on the uniaxial material models. A variety of theoretical models were developed to address the various mechanisms including: an analytical yarn pullout model; a nonlinear finite difference fabric pullout model; a nonlinear finite difference tension model; closed-form solutions for strain-softening materials; closed-form solutions for strain-softening/hardening materials; and closed-form solutions for

  20. Selective Carbon Fiber Reinforced Nylon 66 Spur Gears: Development and Performance

    NASA Astrophysics Data System (ADS)

    Senthilvelan, S.; Gnanamoorthy, R.

    2006-01-01

    A new design methodology is developed to mold the polymer spur gears with high strength fiber reinforcement only in the highly stressed region. High performance high cost short carbon fiber reinforced Nylon 66 is used in the highly stressed tooth region and low cost unreinforced Nylon 66 is used in the hub region. Two different geometries, circular and spline shaped hubs were used for developing the selective reinforced gears by multi-shot injection-molding process. Joint strength of the selectively reinforced gear was estimated using shear tests. Clear hub and tooth region separation without any distortion was observed in joint shear tests. A molten material due to fusion bonding was observed at the interfaces. The joint strength was also evaluated by conducting gear fatigue tests using a power absorption test rig at various torque levels and at a constant gear rotational speed. Monolithic reinforced gear and selective reinforced gears with spline hub exhibited similar fatigue behavior. The failure mode depends upon the test torque level. The selective reinforced gears with circular hub showed joint failures at high-test torque levels. Absence of mechanical interlocking feature in the circular hub geometry contributes to the joint failure. Thermal bond, part interference and mechanical interlocking feature provide sufficient joint strength to the selective reinforced gear with spline hub.

  1. Fiber reinforced concrete: Characterization of flexural toughness and some studies on fiber-matrix bond-slip interaction

    NASA Astrophysics Data System (ADS)

    Dubey, Ashish

    One major problem associated with the testing of fiber reinforced concrete specimens under flexural loading is that the measured post-cracking response is severely affected by the stiffness of the testing machine. As a consequence, misleading results are obtained when such a flexural response is used for the characterization of composite toughness. An assessment of a new toughness characterization technique termed the Residual Strength Test Method (RSTM) has been made. In this technique, a stable narrow crack is first created in the specimen by applying a flexural load in parallel with a steel plate under controlled conditions. The plate is then removed, and the specimen is tested in a routine manner in flexure to obtain the post-crack load versus displacement response. Flexural response for a variety of fiber reinforced cementitious composites obtained using the Residual Strength Test Method has been found to correlate very well with those obtained with relatively stiffer test configurations such as closed-loop test machines. The Residual Strength Test Method is found to be effective in differentiating between different fiber types, fiber lengths, fiber configurations, fiber volume fractions, fiber geometries and fiber moduli. In particular, the technique has been found to be extremely useful for testing cement-based composites containing fibers at very low dosages (<0.5% by volume). An analytical model based on shear lag theory is introduced to study the problem of fiber pullout in fiber reinforced composites. The proposed model eliminates limitations of many earlier models and captures essential features of pullout process, including progressive interfacial debonding, Poisson's effect, and variation in interfacial properties during the fiber pullout process. Interfacial debonding is modeled using an interfacial shear strength criterion. Influence of normal contact stress at the fiber-matrix interface is considered using shrink-fit theory, and the interfacial

  2. 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.

  3. Oxidation of Al2O3 continuous fiber-reinforced/NiAl composites

    NASA Technical Reports Server (NTRS)

    Doychak, J.; Nesbitt, J. A.; Noebe, R. D.; Bowman, R. R.

    1992-01-01

    The 1200 C and 1300 C isothermal and cyclic oxidation behavior of Al2O3 continuous fiber-reinforced/NiAl composites were studied. Oxidation resulted in formation of Al2O3 external scales in a similar manner as scales formed on monolithic NiAl. The isothermal oxidation of an Al2O3/NiAl composite resulted in oxidation of the matrix along the fiber/matrix interface near the fiber ends. This oxide acted as a wedge between the fiber and the matrix, and, under cyclic oxidation conditions, led to further oxidation along the fiber lengths and eventual cracking of the composite. The oxidation behavior of composites in which the Al2O3 fibers were sputter coated with nickel prior to processing was much more severe. This was attributed to open channels around the fibers which formed during processing, most likely as a result of the diffusion of the nickel coating into the matrix.

  4. 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.

  5. Finite-Element Analysis of Jute- and Coir-Fiber-Reinforced Hybrid Composite Multipanel Plates

    NASA Astrophysics Data System (ADS)

    Nirbhay, M.; Misra, R. K.; Dixit, A.

    2015-09-01

    Natural-fiber-reinforced polymer composite materials are rapidly gaining interest worldwide both in terms of research and industrial applications. The present work includes the characterization and modeling of jute- and coir-fiber-reinforced hybrid composite materials. The mechanical behavior of a two-panel plate and a sixpanel box structure is analyzed under various loading regimes by using the finite-element software ABAQUS®. Exhaustive parametric studies are also performed to obtain a clear insight into the relationships between various parameters and deflections of the panels and stress distributions in them. Deflections of both the structures are compared and found to be in good agreement with published results. To determine the mechanical behavior of natural-fiber-reinforced composite panels, a finite-element analysis is performed.

  6. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

    NASA Technical Reports Server (NTRS)

    Cox, Sarah B.; Lui, Donovan; Gou, Jihua

    2014-01-01

    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, which allows a shape to be formed prior to the cure, and is then pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Basalt fibers are used for the reinforcement in the composite system. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material.

  7. Clinical evaluation of carbon fiber reinforced carbon endodontic post, glass fiber reinforced post with cast post and core: A one year comparative clinical study

    PubMed Central

    Preethi, GA; Kala, M

    2008-01-01

    Aim: Restoring endodontically treated teeth is one of the major treatments provided by the dental practitioner. Selection and proper use of restorative materials continues to be a source of frustration for many clinicians. There is controversy surrounding the most suitable choice of restorative material and the placement method that will result in the highest probability of successful treatment. This clinical study compares two different varieties of fiber posts and one cast post and core in terms of mobility of crown margin under finger pressure, recurrent caries detected at the crown margin, fracture of the restoration, fracture of the root and periapical and periodontal pathology requiring crown removal over the period of 12months as evaluated by clinical and radiographical examination. Materials and Methods: 30 root canal treated, single rooted maxillary anterior teeth of 25 patients in the age range of 18–60 years where a post retained crown was indicated were selected for the study between January 2007 and August 2007; and prepared in a standard clinical manner. It was divided into 3 groups of 10 teeth in each group. After post space preparation, the Carbon fiber and Glass fiber reinforced posts were cemented with Scotch bond multipurpose plus bonding agent and RelyX adhesive resin cement in the first and second groups respectively. The Cast post and cores were cemented with Zinc Phosphate cement in the third group. Following post- cementation, the preparation was further refined and a rubber base impression was taken for metal-ceramic crowns which was cemented with Zinc Phosphate cement. A baseline periapical radiograph was taken once each crown was cemented. All patients were evaluated after one week (baseline), 3 months, 6 months and one year for following characteristics mobility of crown margin under finger pressure, recurrent caries detected at the crown margin, fracture of the restoration, fracture of the root and periapical and periodontal pathology

  8. Microstructure/Property Relationships for Carbon Fiber Reinforced Aluminum Alloys.

    DTIC Science & Technology

    1985-07-25

    hypodermic syringe and blunted needle . After mounting the fiber, the card containing the fiber is inserted into the test fixture (figure 2). The edges... theory suggesting that this may not necessarily be the case [211. They showed that a weak interface may, 14 in fact, lead to improved composite properties...agree, at least in principle , with Ochai and Murakami’s theory and composites produced from Cornie’s fibers proved to be quite strong longitudinally

  9. 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.

  10. Fiber release from impacted graphite reinforced epoxy composites

    NASA Technical Reports Server (NTRS)

    Babinsky, T. C.

    1980-01-01

    Carbon fibers released from composites by aircraft fires and crashes can cause electrical shorts and consequent equipment damage. This report investigates less vigorous release mechanisms than that previously simulated by explosive burn/blast tests. When AS/3501-6 composites are impacted by various head and weight configurations of a pendulum impactor, less than 0.2 percent by weight of the original sample is released as single fibers. Other fiber release mechanisms studied were air blasts, constant airflow, torsion, flexural, and vibration of composite samples. The full significance of the low single fiber release rates found here is to be evaluated by NASA in their aircraft vulnerability studies.

  11. Mechanical properties and shape memory effect of short fiber reinforced SMP composite

    NASA Astrophysics Data System (ADS)

    Yu, Kai; Lv, Haibao; Yi, Guo; Liu, Yanju; Leng, Jinsong

    2010-04-01

    By adding randomly distributed short fiber into a shape memory polymer (SMP) matrix, both the mechanical properties and the shape memory behavior are improved significantly, overcoming some traditional defects of SMP composite reinforced by long fiber and particles. In this paper, the short fiber reinforced SMP composite are developed for the improvement of the mechanical and thermal properties of styrene-based SMP bulk. The specimens with different chopped fiber weight fractions are prepared, and then their mechanical behavior and electrical properties are investigated. As a result, the resistance against mechanical and thermal mechanical loads in the developed materials increases due to the role of reinforcement fiber. For the conducting composite filled with short carbon fiber, not only the actuation of SMP composite can be driven by low voltage, but also its tensile, bending strength, glass transition temperature, storage modulus and thermal conductivity increase by a factor of filler content of carbon fiber increasing. The results show meaningful guidance for further design and the performance evaluation of such composite materials.

  12. Influence of the curing cycles on the fatigue performance of unidirectional glass fiber reinforced epoxy composites

    NASA Astrophysics Data System (ADS)

    Hüther, Jonas; Brøndsted, Povl

    2016-07-01

    During the manufacturing process of fiber reinforced polymers the curing reaction of the resin results in shrinkage of the resin and introduces internal stresses in the composites. When curing at higher temperatures in order to shorten up the processing time, higher curing stresses and thermal stresses are built up and frozen, as residual stresses occur. In the present work, a glass fiber reinforced epoxy composite laminate with an unidirectional architecture based on non-crimp fabrics with backing fibers is investigated. Three different curing cycles (time-temperature cycles) are used, leading to different levels of internal stresses. The mechanical properties, static strength and fatigue life time, are measured in three different directions of the material, i.e. the fiber direction, 0°, the 30° off axis direction, and the 90° direction transverse to the fiber direction. It is experimentally demonstrated that the resulting residual stresses barely influences the quasi-static mechanical properties of reinforced glass-fiber composites. It is found that the fatigue performance in the 0° direction is significantly influenced by the internal stresses, whereas the fatigue performance in the off axes directions so is not significantly influenced of these stresses. This is related to the observations that the damage mechanisms in the off axes directions are mainly related to shear failure in the matrix and in the interface between fiber and matrix and different from the damage mechanisms in the fiber direction, where the damage initiates in the transverse backing fibers and is directly related to fiber fractures in the load-carrying axial fiber bundles.

  13. Mechanical analysis of three dimensional woven carbon fiber-reinforced composites using fiber-based continuum model

    NASA Astrophysics Data System (ADS)

    Ahn, Hyunchul; An, Yongsan; Yu, Woong-Ryeol

    2016-10-01

    A new numerical method for analyzing the mechanical behavior of three-dimensional (3D) woven carbon fiber-reinforced composites was developed by considering changes in the fiber orientation and calculating the stress increments due to incremental deformations. The model consisted of four steps, starting update of the yarn orientation based on incremental deformation gradient. The stiffness matrix was then computed using the updated yarn orientation. Next, partial damage and propagation were incorporated into the stress calculation using modified ply discount method. The failure conditions were obtained by testing the unidirectional composites and formulated using Puck's criterion. This numerical model was finally implemented into commercial finite element software, ABAQUS, as a user material subroutine. As for experiment, 3D woven composite samples was manufactured using laboratory built-in system and characterized, the results of which were compared with simulated results, demonstrating that the current numerical model can properly predict the mechanical behavior of 3D fiber-reinforced composites.

  14. Electromagnetic modeling of periodically-structured fiber-reinforced single-layer laminate with multiple fibers missing

    NASA Astrophysics Data System (ADS)

    Liu, Z.-C.; Li, C.-Y.; Lesselier, D.; Zhong, Y.

    2016-12-01

    Modeling of periodically-structured, fiber-reinforced laminates with fibers missing is investigated, this applying as well to similarly disorganized photonic crystals at optical frequencies. Parallel cylindrical fibers are periodically embedded within a layer sandwiched between two half-spaces. Absent fibers destroy the periodicity. The supercell concept involving an auxiliary periodic structure provides subsidiary solutions, wherein plane-wave illumination can be analyzed with the help of the Floquet theorem, while the field response due to a line source can be calculated from the pertinent plane-wave expansion. Accuracy, computational efficacy and versatility of the above approaches are illustrated by comprehensive numerical simulations with in particular comparisons to results provided by a finite-element code, all-purpose but computationally demanding, this work seen as the first step to the localization of missing fibers in a damaged laminate and imaging thereof.

  15. Poly(vinylidene fluoride) reinforced by carbon fibers: Structural parameters of fibers and fiber-polymer adhesion

    NASA Astrophysics Data System (ADS)

    Wang, Jianghong; Wu, Defeng; Li, Xiang; Zhang, Ming; Zhou, Weidong

    2012-10-01

    Poly(vinylidene fluoride) (PVDF) composites containing carbon fibers (CFs) with or without surface treatment were prepared via melt mixing. The mechanical properties of the PVDF/CF composites were then studied to explore the relations between the short-range and long-range structures of CFs and the properties of the composites. The results showed that the presence of CFs had a reinforcement effect on the PVDF and the Nielsen model was used to describe the concentration effect of CFs, especially at the lower concentration levels. The short-range aspect ratio structure and the long-range orientation structure of the CFs are the two most important structures that affected the final properties of the composites. The effective aspect ratio and orientation degree of the CFs in the PVDF matrix can be evaluated by the Halpin-Tsai and the Krenchel-COX models, which agree well with the experimental observations. After surface treatment, the CFs show stronger reinforcement effect due to reduced interfacial tension and increased interfacial area between two phases

  16. Mussel-inspired catecholamine polymers as new sizing agents for fiber-reinforced composites

    NASA Astrophysics Data System (ADS)

    Lee, Wonoh; Lee, Jea Uk; Byun, Joon-Hyung

    2015-04-01

    Mussel-inspired catecholamine polymers (polydopamine and polynorepinephrine) were coated on the surface of carbon and glass fibers in order to increase the interfacial shear strength between fibers and polymer matrix, and consequently the interlaminar shear strength of fiber-reinforced composites. By utilizing adhesive characteristic of the catecholamine polymer, fiber-reinforced composites can become mechanically stronger than conventional composites. Since the catecholamine polymer is easily constructed on the surface by the simultaneous polymerization of its monomer under a weak basic circumstance, it can be readily coated on micro-fibers by a simple dipping process without any complex chemical treatments. Also, catecholamines can increase the surface free energy of micro-fibers and therefore, can give better wettability to epoxy resin. Therefore, catecholamine polymers can be used as versatile and effective surface modifiers for both carbon and glass fibers. Here, catecholamine-coated carbon and glass fibers exhibited higher interfacial shear strength (37 and 27% increases, respectively) and their plain woven composites showed improved interlaminar shear strength (13 and 9% increases, respectively) compared to non-coated fibers and composites.

  17. Reinforcement of conventional glass-ionomer restorative material with short glass fibers.

    PubMed

    Hammouda, Ibrahim M

    2009-01-01

    This study investigated the strengthening effect of glass fibers when added to conventional glass-ionomer restorative material. Glass fibers were incorporated into glass-ionomer powder in 3 wt% and 5 wt%. The fibers used had 1 mm length and 10 microm thickness. These criteria of fiber length, diameter, and concentration represent a new approach for reinforcing conventional glass-ionomer [Medifill, conventional restorative glass-ionomer]. The mechanical properties tested were diametral tensile strength, hardness, flexural strength, flexural modulus and fracture toughness after 24-h and 7-days of storage in deionized water. Glass short fibers were mixed thoroughly into the glass-ionomer powder before mixing with the cement liquid. Samples of specific dimensions were prepared for each time interval and fiber loading according to the manufacturer's instructions and international standards. Hardness was measured using a micro-hardness tester at 100 gram applied load for 15 s. The other mechanical properties were measured using a Lloyd universal testing machine. The results showed increased diametral tensile strength, flexural strength, flexural modulus, and fracture toughness by the addition of glass fibers. There was an appreciable increase of the tested mechanical properties of glass-ionomer restorative material as a result of increasing fiber loading and water storage for 1 week. It was concluded that conventional glass-ionomer can be reinforced by the addition of short glass fibers.

  18. Behavior of Concrete Panels Reinforced with Synthetic Fibers, Mild Steel, and GFRP Composites Subjected to Blasts

    SciTech Connect

    C. P. Pantelides; T. T. Garfield; W. D. Richins; T. K. Larson; J. E. Blakeley

    2012-03-01

    The paper presents experimental data generated for calibrating finite element models to predict the performance of reinforced concrete panels with a wide range of construction details under blast loading. The specimens were 1.2 m square panels constructed using Normal Weight Concrete (NWC) or Fiber Reinforced Concrete (FRC). FRC consisted of macro-synthetic fibers dispersed in NWC. Five types of panels were tested: NWC panels with steel bars; FRC panels without additional reinforcement; FRC panels with steel bars; NWC panels with glass fiber reinforced polymer (GFRP) bars; and NWC panels reinforced with steel bars and external GFRP laminates on both faces. Each panel type was constructed with three thicknesses: 152 mm, 254 mm, and 356 mm. FRC panels with steel bars had the best performance for new construction. NWC panels reinforced with steel bars and external GFRP laminates on both faces had the best performance for strengthening or rehabilitation of existing structures. The performance of NWC panels with GFRP bars was strongly influenced by the bar spacing. The behavior of the panels is classified in terms of damage using immediate occupancy, life safety, and near collapse performance levels. Preliminary dynamic simulations are compared to the experimental results.

  19. Allergic contact dermatitis from a nonbisphenol A epoxy in a graphite fiber reinforced epoxy laminate.

    PubMed

    Mathias, C G

    1987-09-01

    An employee of the Composites Division of an aircraft engine manufacturing firm developed dermatitis associated with the handling of a graphite fiber reinforced epoxy laminate (epoxy prepreg). Patch test investigation demonstrated that the responsible causal agent was the nonbisphenol A epoxy binder, 4-glycidyloxy-N, N-diglycidylaniline. A patch test with bisphenol A epoxy from a standard patch test screening series was negative. Subsequent interviews with employees of the Composites Division suggested that a relative lack of awareness of the cutaneous hazards of fiber reinforced epoxy laminates, compared with liquid epoxy resin systems, may be an important risk factor for allergic sensitization to these composite materials.

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

    SciTech Connect

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

    1994-12-31

    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.

  1. Comparison of mechanical and tribotechnical properties of UHMWPE reinforced with basalt fibers and particles

    NASA Astrophysics Data System (ADS)

    Panin, S. V.; Kornienko, L. A.; Alexenko, V. O.; Qitao, Huang; Ivanova, L. R.

    2016-11-01

    Mechanical and tribotechnical properties of UHMWPE composites reinforced with basalt fibers and particles under dry sliding friction and abrasion were investigated. It is shown that adding of the basalt particles provides higher wear resistance under the dry sliding friction while at abrasion filling by the basalt fibers is more efficient since the wear resistance of the reinforced UHMWPE composites is by 3.7 times higher in contrast with the neat polymer. Wear mechanisms of the polymeric UHMWPE composites under various types of wear are discussed.

  2. NDE of Fiber Reinforced Foam Composite Structures for Future Aerospace Vehicles

    NASA Technical Reports Server (NTRS)

    Walker, james; Roth, Don; Hopkins, Dale

    2010-01-01

    This slide presentation reviews the complexities of non-destructive evaluation (NDE) of fiber reinforced foam composite structures to be used for aerospace vehicles in the future.Various views of fiber reinforced foam materials are shown and described. Conventional methods of NDE for composites are reviewed such as Micro-computed X-Ray Tomography, Thermography, Shearography, and Phased Array Ultrasonics (PAUT). These meth0ods appear to work well on the face sheet and face sheet ot core bond, they do not provide adequate coverage for the webs. There is a need for additional methods that will examine the webs and web to foam core bond.

  3. Behavior of fiber reinforced sandy slopes under seepage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seepage flow is a major contributor to instability of natural hill slopes, river banks and engineered embankments. In order to increase the factor of safety, an emerging technology involves the inclusion of synthetic fibers in the soil. The addition of tension resisting fibers has a favorable effec...

  4. Continuous unidirectional fiber reinforced composites: Fabrication and testing

    NASA Technical Reports Server (NTRS)

    Weber, M. D.; Spiegel, F. X.; West, Harvey A.

    1994-01-01

    The study of the anisotropic mechanical properties of an inexpensively fabricated composite with continuous unidirectional fibers and a clear matrix was investigated. A method has been developed to fabricate these composites with aluminum fibers and a polymer matrix. These composites clearly demonstrate the properties of unidirectional composites and cost less than five dollars each to fabricate.

  5. Multiwalled carbon nanotube (MWCNT) reinforced cellulose fibers by electrospinning.

    PubMed

    Lu, Ping; Hsieh, You-Lo

    2010-08-01

    Multiwalled carbon nanotubes (MWCNTs) were successfully incorporated in ultrafine cellulose fibers by electrospinning MWCNT-loaded cellulose acetate (CA) solutions, followed by deacetylation of CA to cellulose (cell). The mean fiber diameter reduced from 321 nm of the as-spun fibers to 257 and 228 nm of those with 0.11 and 0.55 wt % MWCNTs, respectively, and became more uniform. Hydrolysis of CA to cell further reduced the mean fiber sizes by another 8-16%. The MWCNTs were observed to be well-aligned along the fiber axes. The MWCNT/cell composite fibers had increased specific surface, from 4.27 m(2)/g to 5.07 and 7.69 m(2)/g at 0.11 and 0.55 wt % MWCNTs, respectively, and much improved water wettability. The mechanical properties of the fibers were also greatly enhanced with increased MWCNT loading levels. The fact that MWCNTs were observed in only about a third of the fibers at a very low 0.55 wt % loading suggests significantly higher tensile strength may be achieved by a further increase in MWCNT loadings.

  6. Statistical variations in impact resistance of steel fiber-reinforced concrete subjected to drop weight test

    SciTech Connect

    Nataraja, M.C.; Dhang, N.; Gupta, A.P.

    1999-07-01

    The variation in impact resistance of steel fiber-reinforced concrete and plain concrete as determined from a drop weight test is reported. The observed coefficients of variation are about 57 and 46% for first-crack resistance and the ultimate resistance in the case of fiber concrete and the corresponding values for plain concrete are 54 and 51%, respectively. The goodness-of-fit test indicated poor fitness of the impact-resistance test results produced in this study to normal distribution at 95% level of confidence for both fiber-reinforced and plain concrete. However, the percentage increase in number of blows from first crack to failure for both fiber-reinforced concrete and as well as plain concrete fit to normal distribution as indicated by the goodness-of-fit test. The coefficient of variation in percentage increase in the number of blows beyond first crack for fiber-reinforced concrete and plain concrete is 51.9 and 43.1%, respectively. Minimum number of tests required to reliably measure the properties of the material can be suggested based on the observed levels of variation.

  7. Carbon Fiber Reinforced Glass Matrix Composites for Structural Space Based Applications

    DTIC Science & Technology

    1989-07-31

    1988) 2745-2752. 2 R89-917704-1 10. V. C. Nardone and K. M. Prewo, "Tensile Performance of Carbon-Fibre-Reinforced Glass," J. Mater. Sci., 23 (1988...168-180. 11. K. M. Prewo and V. C. Nardone , "Carbon Fiber Reinforced Glass Matrix Composites for Space Based Applications," UTRC Report R86-917161-1...Mater. Sci., 23 (1988) 2745-2752. 11. V. C. Nardone and K. M. Prewo, "Tensile Performance of Carbon-Fibre-Reinforced Glass," J. Mater. Sci., 23 (1988

  8. Reinforcement of a porous collagen scaffold with surface-activated PLA fibers.

    PubMed

    Liu, Xi; Huang, Changbin; Feng, Yujie; Liang, Jie; Fan, Yujiang; Gu, Zhongwei; Zhang, Xingdong

    2010-01-01

    A hybrid porous collagen scaffold mechanically reinforced with surface-activated poly(lactic acid) (PLA) fiber was prepared. PLA fibers, 20 mum in diameter and 1 mm in length, were aminolyzed with hexanediamine to introduce free amino groups on the surfaces. After the amino groups were transferred to aldehyde groups by treatment with glutaraldehyde, different amounts (1.5, 3, 5 and 8 mg) of surface-activated PLA fibers were homogeneously mixed with 2 ml type-I collagen solution (pH 2.8, 0.6 wt%). This mixture solution was then freeze-dried and cross-linked to obtain collagen sponges with surface-activated PLA fiber. Scanning electron microscopy observation indicated that the collagen sponges had a highly interconnected porous structure with an average pore size of 170 mum, irrespective of PLA fiber incorporation. The dispersion of surface-activated PLA fibers was homogeneous in collagen sponge, in contrast to unactivated PLA fibers. The compression modulus test results showed that, compared with unactivated PLA fibers, the surface-activated PLA fibers enhanced the resistance of collagen sponge to compression more significantly. Cytotoxicity assay by MTT test showed no cytotoxicity of these collagen sponges. L929 mouse fibroblast cell-culture studies in vitro revealed that the number of L929 cells attached to the collagen sponge with surface-activated PLA fibers, both 6 h and 24 h after seeding, was higher than that in pure collagen sponge and sponge with unactivated PLA fibers. In addition, a better distribution of cells infiltrated in collagen sponge with surface-activated PLA fibers was observed by histological staining. These results indicated that the collagen sponge reinforced with surface-activated PLA fibers is a promising biocompatible scaffold for tissue engineering.

  9. Numerical simulation of ultrasonic wave propagation in fiber reinforced plastic using image-based modeling

    NASA Astrophysics Data System (ADS)

    Mizokami, Naoya; Nakahata, Kazuyuki; Ogi, Keiji; Yamawaki, Hisashi; Shiwa, Mitsuharu

    2017-02-01

    The use of fiber reinforced plastics (FRPs) as structural components has significantly increased in recent years. FRPs are made of stacks of plies, each of which is reinforced by fibers. When modeling ultrasonic wave propagation in FRPs, it is important to introduce three-dimensional mesoscopic and microscopic structures to account for the anisotropy and heterogeneity caused by fiber orientation and the lay-up of laminates. In this study, a finite element method using an image-based modeling is applied to simulation of ultrasonic wave propagation in a carbon FRP (CFRP). Here, the elastic stiffness of a single ply is determined using a homogenization method, where a CFRP microstructure is incorporated on the basis of a two-scale asymptotic expansion. The wave propagation in a CFRP specimen composed of unidirectionally aligned fibers is calculated, and the simulation results are compared to visualization results obtained for ultrasonic wave propagation using a laser scanning device.

  10. Numerically design the injection process parameters of parts fabricated with ramie fiber reinforced green composites

    NASA Astrophysics Data System (ADS)

    Chen, L. P.; He, L. P.; Chen, D. C.; Lu, G.; Li, W. J.; Yuan, J. M.

    2017-01-01

    The warpage deformation plays an important role on the performance of automobile interior components fabricated with natural fiber reinforced composites. The present work investigated the influence of process parameters on the warpage behavior of A pillar trim made of ramie fiber (RF) reinforced polypropylene (PP) composites (RF/PP) via numerical simulation with orthogonal experiment method and range analysis. The results indicated that fiber addition and packing pressure were the most important factors affecting warpage. The A pillar trim can achieved the minimum warpage value as of 2.124 mm under the optimum parameters. The optimal process parameters are: 70% percent of the default value of injection pressure for the packing pressure, 20 wt% for the fiber addition, 185 °C for the melt °C for the mold temperature, 7 s for the filling time and 17 s for the packing time.

  11. Mechanical Properties of Sisal/Coir Fiber Reinforced Hybrid Composites Fabricated by Cold Pressing Method

    NASA Astrophysics Data System (ADS)

    Akash; Sreenivasa Rao, K. V.; Venkatesha Gupta, N. S.; kumar, D. S. Arun

    2016-09-01

    Bio-composites have less density and are environmental friendly materials that require less energy during production and subsequent machining. This paper reports the mechanical and water absorption properties of sodium hydroxide (NaOH) treated sisal and coir fiber reinforced epoxy resin thermo set hybrid composites. The hybrid composites were prepared by traditional cold pressing method at room temperature with applied pressure of 410.4 kg/cm2 for 3 hours pressurization time. The mechanical properties were characterized according to ASTM standards. Hybrid composites with 40wt% of sisal and coir fiber were found to possess higher tensile strength of 48.2MPa and flexural strength of 76.68 MPa among the fabricated hybrid composite specimens. Absorption of water increases with increasing fiber volume. The experimental result also show that the sisal and coir fibers are promising reinforcement for use in low cost bio-composites which have high strength to weight ratio.

  12. Characteristics of fatigue life and damage accumulation of short fiber-reinforced polymer composites

    SciTech Connect

    Yokobori, A.T. Jr.; Takeda, Hidetoshi; Adachi, Takeshi; Ha, J.C.; Yokobori, Takeo

    1996-12-31

    The relation between fatigue life and damage accumulation of fiber-reinforced polymer composite (FRP) is not yet clarified. For practical use of FRP, it is necessary to relate the fatigue life to the mechanism of damage accumulation. Damage formation is controlled by the mechanical behavior of the interface between the matrix and fiber. The authors used short glass fiber-reinforced polycarbonate composite in the experiments. By using an in situ (real time) observational fatigue testing machine, they investigated the relationship between fatigue life and damage accumulation. From these results, the fatigue life of this material was found to be dominated by damage accumulation which results from microfracture at the interface between the matrix and fiber. This microfracture is controlled by a cycle-dependent mechanism.

  13. Effects of Temperature, Oxidation and Fiber Preforms on Fatigue Life of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-08-01

    In this paper, the effects of temperature, oxidation and fiber preforms on the fatigue life of carbon fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) have been investigated. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface wear model and fibers statistical failure model at room temperature, and interface/fibers oxidation model, interface wear model and fibers statistical failure model at elevated temperatures in the oxidative environments. When the broken fibers fraction approaches to the critical value, the composites fatigue fracture. The fatigue life S-N curves and fatigue limits of unidirectional, cross-ply, 2D, 2.5D and 3D C/SiC composites at room temperature, 800 °C in air, 1100, 1300 and 1500 °C in vacuum conditions have been predicted.

  14. Mechanical Properties of a Unidirectional Basalt-Fiber-Reinforced Plastic Under a Loading Simulating Operation Conditions

    NASA Astrophysics Data System (ADS)

    Lobanov, D. S.; Slovikov, S. V.

    2017-01-01

    The results of experimental investigations of unidirectional composites based on basalt fibers and different marks of epoxy resins are presented. Uniaxial tensile tests were carried out using a specimen fixation technique simulating the operation conditions of structures. The mechanical properties of the basalt-fiber-reinforced plastics (BFRPs) were determined. The diagrams of loading and deformation of BFRP specimens were obtain. The formulations of the composites with the highest mechanical properties were revealed.

  15. Effect of random/aligned nylon-6/MWCNT fibers on dental resin composite reinforcement.

    PubMed

    Borges, Alexandre L S; Münchow, Eliseu A; de Oliveira Souza, Ana Carolina; Yoshida, Takamitsu; Vallittu, Pekka K; Bottino, Marco C

    2015-08-01

    The aims of this study were (1) to synthesize and characterize random and aligned nanocomposite fibers of multi-walled carbon nanotubes (MWCNT)/nylon-6 and (2) to determine their reinforcing effects on the flexural strength of a dental resin composite. Nylon-6 was dissolved in hexafluoropropanol (10 wt%), followed by the addition of MWCNT (hereafter referred to as nanotubes) at two distinct concentrations (i.e., 0.5 or 1.5 wt%). Neat nylon-6 fibers (without nanotubes) were also prepared. The solutions were electrospun using parameters under low- (120 rpm) or high-speed (6000 rpm) mandrel rotation to collect random and aligned fibers, respectively. The processed fiber mats were characterized by scanning (SEM) and transmission (TEM) electron microscopies, as well as by uni-axial tensile testing. To determine the reinforcing effects on the flexural strength of a dental resin composite, bar-shaped (20×2×2 mm(3)) resin composite specimens were prepared by first placing one increment of the composite, followed by one strip of the mat, and one last increment of composite. Non-reinforced composite specimens were used as the control. The specimens were then evaluated using flexural strength testing. SEM was done on the fractured surfaces. The data were analyzed using ANOVA and the Tukey׳s test (α=5%). Nanotubes were successfully incorporated into the nylon-6 fibers. Aligned and random fibers were obtained using high- and low-speed electrospinning, respectively, where the former were significantly (p<0.001) stronger than the latter, regardless of the nanotubes׳ presence. Indeed, the dental resin composite tested was significantly reinforced when combined with nylon-6 fibrous mats composed of aligned fibers (with or without nanotubes) or random fibers incorporated with nanotubes at 0.5 wt%.

  16. Corrosion detection of steel reinforced concrete using combined carbon fiber and fiber Bragg grating active thermal probe

    NASA Astrophysics Data System (ADS)

    Li, Weijie; Ho, Siu Chun Michael; Song, Gangbing

    2016-04-01

    Steel reinforcement corrosion is one of the dominant causes for structural deterioration for reinforced concrete structures. This paper presents a novel corrosion detection technique using an active thermal probe. The technique takes advantage of the fact that corrosion products have poor thermal conductivity, which will impede heat propagation generated from the active thermal probe. At the same time, the active thermal probe records the temperature response. The presence of corrosion products can thus be detected by analyzing the temperature response after the injection of heat at the reinforcement-concrete interface. The feasibility of the proposed technique was firstly analyzed through analytical modeling and finite element simulation. The active thermal probe consisted of carbon fiber strands to generate heat and a fiber optic Bragg grating (FBG) temperature sensor. Carbon fiber strands are used due to their corrosion resistance. Wet-dry cycle accelerated corrosion experiments were performed to study the effect of corrosion products on the temperature response of the reinforced concrete sample. Results suggest a high correlation between corrosion severity and magnitude of the temperature response. The technique has the merits of high accuracy, high efficiency in measurement and excellent embeddability.

  17. Fiber-Reinforced Reactive Nano-Epoxy Composites

    NASA Technical Reports Server (NTRS)

    Zhong, Wei-Hong

    2011-01-01

    An ultra-high-molecular-weight polyethylene/ matrix interface based on the fabrication of a reactive nano-epoxy matrix with lower surface energy has been improved. Enhanced mechanical properties versus pure epoxy on a three-point bend test include: strength (25 percent), modulus (20 percent), and toughness (30 percent). Increased thermal properties include higher Tg (glass transition temperature) and stable CTE (coefficient of thermal expansion). Improved processability for manufacturing composites includes faster wetting rates on macro-fiber surfaces, lower viscosity, better resin infusion rates, and improved rheological properties. Improved interfacial adhesion properties with Spectra fibers by pullout tests include initial debonding force of 35 percent, a maximum pullout force of 25 percent, and energy to debond at 65 percent. Improved mechanical properties of Spectra fiber composites (tensile) aging resistance properties include hygrothermal effects. With this innovation, high-performance composites have been created, including carbon fibers/nano-epoxy, glass fibers/nano-epoxy, aramid fibers/ nano-epoxy, and ultra-high-molecularweight polyethylene fiber (UHMWPE).

  18. Rate dependent response and failure of a ductile epoxy and carbon fiber reinforced epoxy composite

    SciTech Connect

    Brown, Eric N; Rae, Philip J; Dattelbaum, Dana M; Stahl, David B

    2010-01-01

    An extensive characterization suite has been performed on the response and failure of a ductile epoxy 55A and uniaxial carbon fiber reinforced epoxy composite of IM7 fibers in 55A resin from the quasistatic to shock regime. The quasistatic and intermediate strain rate response, including elastic modulus, yield and failure have are characterized by quasistatic, SHPB, and DMA measurements as a function of fiber orientation and temperature. The high strain rate shock effect of fiber orientation in the composite and response of the pure resin are presented for plate impact experiments. It has previously been shown that at lower impact velocities the shock velocity is strongly dependent on fiber orientation but at higher impact velocity the in-plane and through thickness Hugoniots converge. The current results are compared with previous studies of the shock response of carbon fiber composites with more conventional brittle epoxy matrices. The spall response of the composite is measured and compared with quasistatic fracture toughness measurements.

  19. Damage evaluation of reinforced concrete frame based on a combined fiber beam model

    NASA Astrophysics Data System (ADS)

    Shang, Bing; Liu, ZhanLi; Zhuang, Zhuo

    2014-04-01

    In order to analyze and simulate the impact collapse or seismic response of the reinforced concrete (RC) structures, a combined fiber beam model is proposed by dividing the cross section of RC beam into concrete fiber and steel fiber. The stress-strain relationship of concrete fiber is based on a model proposed by concrete codes for concrete structures. The stress-strain behavior of steel fiber is based on a model suggested by others. These constitutive models are implemented into a general finite element program ABAQUS through the user defined subroutines to provide effective computational tools for the inelastic analysis of RC frame structures. The fiber model proposed in this paper is validated by comparing with experiment data of the RC column under cyclical lateral loading. The damage evolution of a three-dimension frame subjected to impact loading is also investigated.

  20. Stress-Rupture of New Tyranno Si-C-O-Zr Fiber Reinforced Minicomposites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.

    1999-01-01

    Minicomposites consisting of two varieties of Zr containing SiC-based fibers from Ube (Tyranno) with BN interphases and CVI SiC matrices were studied. The two fiber-types were the ZMI and ZE fiber-types that contain approximately 8 and 2% oxygen, respectively. The minicomposites were precracked and tested under constant load testing at temperatures ranging from 700 to 1200 C. The data were then compared to the rupture behavior of Hi- Nicalon (TM) fiber reinforced minicomposites tested under identical conditions. It was found that the Ube fiber-types had stress rupture life equivalent to Hi- Nicalon (TM) over the entire temperature range. A potential benefit of the ZMI fiber-type is that it offers rupture properties almost as good as Hi-Nicalon (TM) at the cost of ceramic grade Nicalon (TM).

  1. Composite PLA scaffolds reinforced with PDO fibers for tissue engineering.

    PubMed

    Cont, Liana; Grant, David; Scotchford, Colin; Todea, Milica; Popa, Catalin

    2013-02-01

    Novel composite scaffolds were produced using long continuous bidirectional fibers embedded in an electrospun matrix, with the aim of using them in soft tissue engineering applications. The fibers are of polydioxanone and the matrix of polylactic acid. The novel manufacturing method consists of direct electrospinning performed on both sides of a collector that supports the already arranged fibers. The scaffolds were tested in vitro using 3T3 mouse fibroblasts as-obtained or functionalized with biotin or poly (dopamine). Functionalization did not significantly affect cells attachment, metabolic activity, or proliferation, but poly (dopamine) was proven to be effective in inducing hydrophilicity to the surface.

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

    SciTech Connect

    Silber, Martin; Wenzelburger, Martin; Gadow, Rainer

    2007-04-07

    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.

  3. Tailoring of fiber-reinforced cementitious composites (FRCC) for flexural strength and reliability

    NASA Astrophysics Data System (ADS)

    Obla, Karthikeyan Hariya

    Bending is the most common form of loading for many construction elements. The bending strength or Modulus of Rupture (MOR) and flexural ductility are therefore critical properties particularly for those elements which are not reinforced by rebars. Such elements include highway barriers, certain wall panels, thin sheet elements and small diameter pipes. The tensile and bending strengths of concrete are very low. In addition, as a brittle material, concrete also demonstrates a large variability in bending strength. A large variability in MOR leads to inefficient use of the material since the design strength has to be close to the lower bound of the material's strength distribution. The potential of fiber in improving MOR is well recognized in fiber reinforced concrete. The use of fiber to enhance material reliability is much less studied. This thesis addresses both aspects employing a combination of theoretical and experimental treatments. Research findings are reported as Part I and Part II of this thesis. Carbon fibers are increasingly attractive for reinforcing cementitious composites. They can be manufactured to yield a wide range in modulus and strength. Carbon fibers are non-corrosive, and fire and alkali. In addition, the price of pitch based carbon fibers are dropping rapidly to make them economically viable for the building and construction industries. In Part I of the thesis, a study on the optimization of the bending strength of carbon FRCC using a fracture based flexural model that links the fiber, interface, and matrix micro-parameters to composite bending strength is presented. Carbon fiber, interface and matrix parameters were tailored to yield optimal properties such as high MOR and ductility. Four point bend tests were conducted on CFRCCs to confirm the findings. Some problems specially affecting carbon FRCCs such as fiber breakage during mixing were also studied and its effects on composite uniaxial tensile properties analyzed by developing new

  4. 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.

  5. Producing Fiber Reinforced Composites Having Dense Ceramic Matrices

    NASA Technical Reports Server (NTRS)

    Behrendt, Donald R. (Inventor); Singh, Mrityunjay (Inventor)

    1999-01-01

    A fiber preform is partially infiltrated with a ceramic material. A porous solid polymer is formed by reaction forming the infiltrated preform which is then pyrolized. Microporous carbon in the composite matrix is converted into silicon carbide.

  6. Bond Mechanisms in Fiber Reinforced Cement-Based Composites

    DTIC Science & Technology

    1989-08-01

    such as latex, fly ash, and microsilica . 0 Also the medium from which the fiber was pulled out included a control mix without fibers, mixes with 1...significant improvement in the peak load (up to four times), but has no effect on the post-peak response. The addition of microsilica does not seem to...strength decreases with addition of microsilica and increases drastically with the addition of latex. Parameswaran and Rajagopalan [48] recognized the fact

  7. Graphite-Fiber-Reinforced Glass-Matrix Composite

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Dicus, D. L.

    1982-01-01

    G/GI structural composite material made of graphite fibers embedded in borosilicate glass exhibit excellent strength, fracture toughness, and dimensional stability at elevated temperatures. It is made by passing graphite-fiber yarn through slurry containing suspension of fine glass particles in carrier liquid and winding on drum to produce prepegged uniaxial tape. After drying, tapes are cut into appropriate lengths and laid up in graphite die in desired stacking scheme. Stack is consolidated by hot pressing in furnace.

  8. An In Vitro Comparative Evaluation of Fracture Resistance of Custom Made, Metal, Glass Fiber Reinforced and Carbon Reinforced Posts in Endodontically Treated Teeth

    PubMed Central

    Sonkesriya, Subhash; Olekar, Santosh T; Saravanan, V; Somasunderam, P; Chauhan, Rashmi Singh; Chaurasia, Vishwajit Rampratap

    2015-01-01

    Background: Posts are used to enhance crown buildup in pulpless teeth with destructed crown portion. Different types of post are used in endodontically treated teeth. The aim of the present in vitro study was to evaluate fracture resistance of custom made, metal, glass fiber reinforced and carbon reinforced posts in endodontically treated teeth. Materials and Methods: An in vitro study was carried out on extracted 40 human maxillary central incisor teeth, which was divided into four groups with 10 samples in each group with custom made, metal post, glass fiber reinforced, and carbon reinforced posts. The samples were decoronated at cemento-enamel junction and endodontically treated. Post space was prepared and selected posts were cemented. The composite cores were prepared at the height of 5 mm and samples mounted on acrylic blocks. Later fracture resistance to the compressive force of samples was measured using Universal Testing Machine. Results: The maximum resistance to the compressive force was observed in carbon reinforced and glass fiber reinforced posts compared others which is statistically significant (P > 0.001) and least was seen in custom fabricated post. Conclusion: It is concluded that carbon reinforced fiber post and glass fiber posts showed good fracture resistance compared to custom made and metal posts. PMID:26028904

  9. Method of Manufacturing Carbon Fiber Reinforced Carbon Composite Valves

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    A method for forming a carbon composite valve for internal combustion engines is discussed. The process includes the steps of braiding carbon fiber into a rope thereby forming a cylindrically shaped valve stem portion and continuing to braid said fiber while introducing into the braiding carbon fiber rope a carbon matrix plug having an outer surface in a net shape of a valve head thereby forming a valve head portion. The said carbon matrix plug acting as a mandrel over which said carbon fiber rope is braided, said carbon fiber rope and carbon matrix plug forming a valve head portion suitable for mating with a valve seat; cutting said braided carbon valve stem portion at one end to form a valve tip and cutting said braided carbon fiber after said valve head portion to form a valve face and thus provide a composite valve preform; and densifying said preform by embedding the braided carbon in a matrix of carbon to convert said valve stem portion to a valve stem and said valve head portion to a valve head thereby providing said composite valve.

  10. Fungal degradation of fiber-reinforced composite materials

    NASA Technical Reports Server (NTRS)

    Gu, J. D.; Lu, C.; Mitchell, R.; Thorp, K.; Crasto, A.

    1997-01-01

    As described in a previous report, a fungal consortium isolated from degraded polymeric materials was capable of growth on presterilized coupons of five composites, resulting in deep penetration into the interior of all materials within five weeks. Data describing the utilization of composite constituents as nutrients for the microflora are described in this article. Increased microbial growth was observed when composite extract was incubated with the fungal inoculum at ambient temperatures. Scanning electron microscopic observation of carbon fibers incubated with a naturally developed population of microorganisms showed the formation of bacterial biofilms on the fiber surfaces, suggesting possible utilization of the fiber chemical sizing as carbon and energy sources. Electrochemical impedance spectroscopy was used to monitor the phenomena occurring at the fiber-matrix interfaces. Significant differences were observed between inoculated and sterile panels of the composite materials. A progressive decline in impedance was detected in the inoculated panels. Several reaction steps may be involved in the degradation process. Initial ingress of water into the resin matrix appeared to be followed by degradation of fiber surfaces, and separation of fibers from the resin matrix. This investigation suggested that composite materials are susceptible to microbial attack by providing nutrients for growth.

  11. 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.

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

    SciTech Connect

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

    2015-05-22

    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.

  13. 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.

  14. Preparation and characterization of glass fibers - polymers (epoxy) bars (GFRP) reinforced concrete for structural applications

    NASA Astrophysics Data System (ADS)

    Alkjk, Saeed; Jabra, Rafee; Alkhater, Salem

    2016-06-01

    The paper presents some of the results from a large experimental program undertaken at the Department of Civil Engineering of Damascus University. The project aims to study the ability to reinforce and strengthen the concrete by bars from Epoxy polymer reinforced with glass fibers (GFRP) and compared with reinforce concrete by steel bars in terms of mechanical properties. Five diameters of GFRP bars, and steel bars (4mm, 6mm, 8mm, 10mm, 12mm) tested on tensile strength tests. The test shown that GFRP bars need tensile strength more than steel bars. The concrete beams measuring (15cm wide × 15cm deep × and 70cm long) reinforced by GFRP with 0.5 vol.% ratio, then the concrete beams reinforced by steel with 0.89 vol.% ratio. The concrete beams tested on deflection test. The test shown that beams which reinforced by GFRP has higher deflection resistance, than beams which reinforced by steel. Which give more advantage to reinforced concrete by GFRP.

  15. PILOT-SCALE EVALUATION OF NEW RESIN APPLICATION EQUIPMENT FOR FIBER- REINFORCED PLASTICS

    EPA Science Inventory

    The article gives results of a pilot-scale evaluation of new resin application equipment for fiber- reinforced plastics. The study, an evaluation and comparison of styrene emissions, utilized Magnum's FIT(TM) nozzle with conventional spray guns and flow coaters (operated at both ...

  16. Practical experience of steel fiber reinforced wet shotcrete in large underground construction projects

    SciTech Connect

    Garshol, K.

    1995-12-31

    The paper discusses advantages of SFRS (steel fiber reinforced shotcrete) in underground construction projects, including trends in rock support design; quality and durability of wet mix shotcrete; advantages in safety and working environment and the technical properties of SFRS. Key data from cases illustrate the above. Cost and time factors are highlighted.

  17. A New Generation of Sub Mm Telescopes, Made of Carbon Fiber Reinforced Plastic

    NASA Technical Reports Server (NTRS)

    Mezger, P.; Baars, J. W. M.; Ulich, B. L.

    1984-01-01

    Carbon fiber reinforced plastic (CFRP) appears to be the material most suited for the construction of submillimeter telescopes (SMT) not only for ground-based use but also for space applications. The accuracy of the CFRP reflectors needs to be improved beyond value of the 17 micron rms envisaged for the 10 m SMT.

  18. AN EMPIRICAL MODEL TO PREDICT STYRENE EMISSIONS FROM FIBER-REINFORCED PLASTICS FABRICATION PROCESSES

    EPA Science Inventory

    Styrene is a designated hazardous air pollutant, per the 1990 Clean Air Act Amendments. It is also a tropospheric ozone precursor. Fiber-reinforced plastics (FRP) fabrication is the primary source of anthropogenic styrene emissions in the United States. This paper describes an em...

  19. Failure Characterization of a Fiber Reinforced Ceramic Matrix Composite with Circular Holes

    DTIC Science & Technology

    1991-12-01

    cyanoacrylate glue , one at the side of the hole (on the axis normal to the load direction) and one centered 0.9 cm from the center of the hole, midway between the...such as FormicaT), concrete reinforced with steel rods, and steel-belted tires. Even in nature, wood is a composite material, with cellulose fibers bound

  20. Use of glass fiber-reinforced plastic as an absorber in limestone wet flue gas desulfurization.

    PubMed

    Lin, Haibo

    2008-10-01

    The choice of materials for the spraying and oxidation of pipes directly affect the operation in limestone wet flue gas desulfurization (FGD). There is reason to consider using glass fiber-reinforced plastic (FRP) instead of expensive high nickel alloy for the spraying and oxidation of pipes.

  1. Modeling root-reinforcement with a Fiber-Bundle Model and Monte Carlo simulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper uses sensitivity analysis and a Fiber-Bundle Model (FBM) to examine assumptions underpinning root-reinforcement models. First, different methods for apportioning load between intact roots were investigated. Second, a Monte Carlo approach was used to simulate plants with heartroot, platero...

  2. Seamless metal-clad fiber-reinforced organic matrix composite structures and process for their manufacture

    NASA Technical Reports Server (NTRS)

    Bluck, Raymond M. (Inventor); Bush, Harold G. (Inventor); Johnson, Robert R. (Inventor)

    1990-01-01

    A metallic outer sleeve is provided which is capable of enveloping a hollow metallic inner member having continuous reinforcing fibers attached to the distal end thereof. The inner member is then introduced into outer sleeve until inner member is completely enveloped by outer sleeve. A liquid matrix member is then injected into space between inner member and outer sleeve. A pressurized heat transfer medium is flowed through the inside of inner member, thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. The novelty of this invention resides in the development of a efficient method of producing seamless metal clad fiber reinforced organic matrix composite structures.

  3. Damage Precursor Investigation of Fiber-Reinforced Composite Materials Under Fatigue Loads

    DTIC Science & Technology

    2013-09-01

    Ripley’s K function computed based on optical micrographs for independent experimental observations: (a) shows the short and long range response while...INTENTIONALLY LEFT BLANK. 1 1. Introduction Fiber-reinforced composite materials ( laminated composites and polymer matrix composites...necking or striations). In resin polymers during the damage nucleation process, the interplay between crazing and shear bands has been observed. Depending

  4. Mechanical Properties of Basalt-fiber-reinforced Polyamide-6/Polypropylene Composites

    NASA Astrophysics Data System (ADS)

    Zhang, Z. F.; Xin, Ye

    2014-09-01

    Basalt-fiber-reinforced PP/PA blends were prepared by their homogenization in a twin-screw extruder followed by injection molding. The effects of different relative content of components of the composites obtained on their tensile and impact strength and flexural properties are investigated.

  5. Fracture resistance of abutment screws made of titanium, polyetheretherketone, and carbon fiber-reinforced polyetheretherketone.

    PubMed

    Neumann, Eduardo Aloisio Fleck; Villar, Cristina Cunha; França, Fabiana Mantovani Gomes

    2014-01-01

    Fractured abutment screws may be replaced; however, sometimes, the screw cannot be removed and the entire implant must be surgically removed and replaced. The aim of this study was to compare the fracture resistance of abutment retention screws made of titanium, polyetheretherketone (PEEK) and 30% carbon fiber-reinforced PEEK, using an external hexagonal implant/UCLA-type abutment interface assembly. UCLA-type abutments were fixed to implants using titanium screws (Group 1), polyetheretherketone (PEEK) screws (Group 2), and 30% carbon fiber-reinforced PEEK screws (Group 3). The assemblies were placed on a stainless steel holding apparatus to allow for loading at 45o off-axis, in a universal testing machine. A 200 N load (static load) was applied at the central point of the abutment extremity, at a crosshead speed of 5 mm/minute, until failure. Data was analyzed by ANOVA and Tukey's range test. The titanium screws had higher fracture resistance, compared with PEEK and 30% carbon fiber-reinforced PEEK screws (p < 0.05). In contrast, no statistically significant difference was observed between the fracture resistance of the PEEK and the 30% carbon fiber-reinforced PEEK screws (p> 0.05). Finally, visual analysis of the fractions revealed that 100% of them occurred at the neck of the abutment screw, suggesting that this is the weakest point of this unit. PEEK abutment screws have lower fracture resistance, in comparison with titanium abutment screws.

  6. Complementary methods for nondestructive testing of composite materials reinforced with carbon woven fibers

    NASA Astrophysics Data System (ADS)

    Steigmann, R.; Iftimie, N.; Sturm, R.; Vizureanu, P.; Savin, A.

    2015-11-01

    This paper presents complementary methods used in nondestructive evaluation (NDE) of composite materials reinforced with carbon woven fibers as two electromagnetic methods using sensor with orthogonal coils and sensor with metamaterials lens as well as ultrasound phased array method and Fiber Bragg gratings embedded instead of a carbon fiber for better health monitoring. The samples were impacted with low energy in order to study delamination influence. The electromagnetic behavior of composite was simulated by finite- difference time-domain (FDTD) software, showing a very good concordance with electromagnetic nondestructive evaluation tests.

  7. Predicted inlet gas temperatures for tungsten fiber reinforced superalloy turbine blades

    NASA Technical Reports Server (NTRS)

    Winsa, E. A.; Westfall, L. J.; Petrasek, D. W.

    1978-01-01

    Tungsten fiber reinforced superalloy composite (TFRS) impingement cooled turbine blade inlet gas temperatures were calculated taking into account material spanwise strength, thermal conductivity, material oxidation resistance, fiber-matrix interaction, and coolant flow. Measured values of TFRS thermal conductivities are presented. Calculations indicate that blades made of 30 volume percent fiber content TFRS having a 12,000 N-m/kg stress-to-density ratio while operating at 40 atmospheres and a 0.06 coolant flow ratio could permit a turbine blade inlet gas temperature of over 1900K. This is more than 150K greater than similar superalloy blades.

  8. Porosity characterization of fiber-reinforced ceramic matrix composite using synchrotron X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Zou, C.; Marrow, T. J.; Reinhard, C.; Li, B.; Zhang, C.; Wang, S.

    2016-03-01

    The pore structure and porosity of a continuous fiber reinforced ceramic matrix composite has been characterized using high-resolution synchrotron X-ray computed tomography (XCT). Segmentation of the reconstructed tomograph images reveals different types of pores within the composite, the inter-fiber bundle open pores displaying a "node-bond" geometry, and the intra-fiber bundle isolated micropores showing a piping shape. The 3D morphology of the pores is resolved and each pore is labeled. The quantitative filtering of the pores measures a total porosity 8.9% for the composite, amid which there is about 7.1~ 9.3% closed micropores.

  9. Carbon Fiber Reinforced Carbon Composites Rotary Valves for Internal Combustion Engines

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    Carbon fiber reinforced carbon composite rotary, sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or warp-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties, do not present the sealing and lubrication problems that have prevented rotary, sleeve, and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

  10. Carbon Fiber Reinforced Carbon Composite Rotary Valve for an Internal Combustion Engine

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    Carbon fiber reinforced carbon composite rotary sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or wrap-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties do not present the sealing and lubrication problems that have prevented rotary sleeve and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

  11. Crystalline and tensile properties of carbon nanotube and graphene reinforced polyamide 12 fibers

    NASA Astrophysics Data System (ADS)

    Chatterjee, S.; Nüesch, F. A.; Chu, B. T. T.

    2013-02-01

    The influence of carbon nanotubes (CNTs) and graphene nanoplatelets (GnPs) on the structure and mechanical properties of polyamide 12 (PA12) fibers was investigated. As seen from wide-angle X-ray diffraction analysis the crystallinity index increases with incorporation of nanofillers due to nucleation effects. Marked improvement was noted for mechanical properties of the composites with increase in elastic modulus, yield stress and strength of the fibers. The most significant improvement of a factor of 4 could be observed for elastic modulus with the inclusion of 0.5 wt.% GnP. A comparative study was made between the fibers reinforced with CNTs and GnPs.

  12. Determination of Material Parameters for Microbuckling Analysis of Fiber Reinforced Polymer Matrix Composites

    NASA Astrophysics Data System (ADS)

    Romanowicz, M.

    2015-05-01

    This research focuses on studying the effect of the constitutive law adopted for a matrix material on the compressive response of a unidirectional fiber reinforced polymer matrix composite. To investigate this effect, a periodic unit cell model of a unidirectional composite with an initial fiber waviness and inelastic behavior of the matrix was used. The sensitivity of the compressive strength to the hydrostatic pressure, the flow rule and the fiber misalignment angle were presented. The model was verified against an analytical solution and experimental data. Results of this study indicate that a micromechanical model with correctly identified material parameters provides a useful alternative to theoretical models and experimentation.

  13. An integrated micromechanical and macromechanical approach to fracture behavior of fiber-reinforced composites

    NASA Technical Reports Server (NTRS)

    Mahishi, Jayant M.

    1986-01-01

    A novel integrated micromechanical and macromechanical fracture criterion (IMMFC) was developed for the purpose of characterizing fractures in fiber-reinforced composites. The Griffith energy balance equation was modified to include the energy absorption due to matrix yielding, matrix cracks, fiber breaks, and fiber-matrix interface debonds characteristic for these materials. Parameters which are a measure of the size and density of the microflaws are introduced into the development of the IMMFC, and the concept of the R-curve is used to bridge the micromechanics and macromechanics approaches.

  14. 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.

  15. Interfacial optimization of fiber-reinforced hydrogel composites for soft fibrous tissue applications.

    PubMed

    Holloway, Julianne L; Lowman, Anthony M; VanLandingham, Mark R; Palmese, Giuseppe R

    2014-08-01

    Meniscal tears are the most common orthopedic injuries to the human body, yet the current treatment of choice is a partial meniscectomy, which is known to lead to joint degeneration and osteoarthritis. As a result, there is a significant clinical need to develop materials capable of restoring function to the meniscus following an injury. Fiber-reinforced hydrogel composites are particularly suited for replicating the mechanical function of native fibrous tissues due to their ability to mimic the native anisotropic property distribution present. A critical issue with these materials, however, is the potential for the fiber-matrix interfacial properties to severely limit composite performance. In this work, the interfacial properties of an ultra-high-molecular-weight polyethylene (UHMWPE) fiber-reinforced poly(vinyl alcohol) (PVA) hydrogel are studied. A novel chemical grafting technique, confirmed using X-ray photoelectron spectroscopy, is used to improve UHMWPE-PVA interfacial adhesion. Interfacial shear strength is quantified using fiber pull-out tests. Results indicate significantly improved fiber-hydrogel interfacial adhesion after chemical grafting, where chemically grafted samples have an interfacial shear strength of 256.4±64.3kPa compared to 11.5±2.9kPa for untreated samples. Additionally, scanning electron microscopy of fiber surfaces after fiber pull-out reveal cohesive failure within the hydrogel matrix for treated fiber samples, indicating that the UHMWPE-PVA interface has been successfully optimized. Lastly, inter-fiber spacing is observed to have a significant effect on interfacial adhesion. Fibers spaced further apart have significantly higher interfacial shear strengths, which is critical to consider when optimizing composite design. The results in this study are applicable in developing similar chemical grafting techniques and optimizing fiber-matrix interfacial properties for other hydrogel-based composite systems.

  16. Analytical solution of magnetothermoelastic interaction in a fiber-reinforced anisotropic material

    NASA Astrophysics Data System (ADS)

    Hobiny, Aatef D.; Abbas, Ibrahim A.

    2016-12-01

    The present paper is concerned with the investigation of the analytical solution of a fiber-reinforced anisotropic material under generalized magnetothermoelastic theory using the eigenvalue approach. Based on the Lord-Shulman theory, the formulation is applied to generalized magnetothermoelasticity with one relaxation time. Based on eigenvalue approach, exponential Fourier transform and Laplace techniques, the analytical solutions has been obtained. The inverses of Fourier transforms are obtained analytically. Numerical computations for a fiber-reinforced-like material have been performed and the results are presented graphically. The results of the temperature, displacement components and stress components have been verified numerically and are represented graphically. Comparisons are made with the results predicted by the presence and absence of reinforcement.

  17. Study on the laser irradiation effects on coating reinforced glass fiber/resin composite material

    NASA Astrophysics Data System (ADS)

    Chen, Minsun; Jiang, Houman; Zhang, Tianyu; Zhang, Xiangyu

    2016-10-01

    Two kinds of anti-laser coating made of reflective / ablative resin, called reinforcement schemes of A and B, are applied to the glass fiber reinforced resin matrix composite plate. The anti-laser performance of these samples to the laser operated at the wavelength of 976nm is tested, under the case of a 0.3 Mach tangential airflow pass over the surface of the sample. The experimental results show that the laser damage threshold of the coating reinforced samples have increased more than 50% compared to the original sample, the reinforcement scheme B is better than A. The laser power density damage threshold of the coating reinforced samples to the near infrared laser is higher than 100W/cm2, under the irradiation time is 60 seconds. For the resin reinforced fiber samples, the removal process of the ablation residues has important effects on the perforation time of samples, when there is a strong airflow pass over the surface. The larger laser spot corresponding to the removal of the ablation residues is easier.

  18. Application of nanoindentation testing to study of the interfacial transition zone in steel fiber reinforced mortar

    SciTech Connect

    Wang Xiaohui Jacobsen, Stefan; He Jianying; Zhang Zhiliang; Lee, Siaw Foon; Lein, Hilde Lea

    2009-08-15

    The characteristics of the profiles of elastic modulus and hardness of the steel fiber-matrix and fiber-matrix-aggregate interfacial zones in steel fiber reinforced mortars have been investigated by using nanoindentation and Scanning Electron Microscopy (SEM), where two sets of parameters, i.e. water/binder ratio and content of silica fume were considered. Different interfacial bond conditions in the interfacial transition zones (ITZ) are discussed. For sample without silica fume, efficient interfacial bonds across the steel fiber-matrix and fiber-matrix-aggregate interfaces are shown in low water/binder ratio mortar; while in high water/binder ratio mortar, due to the discontinuous bleeding voids underneath the fiber, the fiber-matrix bond is not very good. On the other hand, for sample with silica fume, the addition of 10% silica fume leads to no distinct presence of weak ITZ in the steel fiber-matrix interface; but the effect of the silica fume on the steel fiber-matrix-aggregate interfacial zone is not obvious due to voids in the vicinity of steel fiber.

  19. A novel basalt fiber-reinforced polylactic acid composite for hard tissue repair.

    PubMed

    Chen, Xi; Li, Yan; Gu, Ning

    2010-08-01

    A basalt fiber (BF) was, for the first time, introduced into a poly(l-lactic acid) (PLLA) matrix as innovative reinforcement to fabricate composite materials for hard tissue repair. Firstly, BF/PLLA composites and pure PLLA were produced by the methods of solution blending and freeze drying. The results showed that basalt fibers can be uniformly dispersed in the PLLA matrix and significantly improve the mechanical properties and hydrophilicity of the PLLA matrix. The presence of basalt fibers may retard the polymer degradation rate and neutralize the acid degradation from PLLA. Osteoblasts were cultured in vitro to evaluate the cytocompatibility of the composite. An MTT assay revealed that osteoblasts proliferated well for 7 days and there was little difference found in their viability on both PLLA and BF/PLLA films, which was consistent with the alkaline phosphatase (ALP) activity results. A fluorescent staining observation showed that osteoblasts grew well on the composites. SEM images displayed that osteoblasts tended to grow along the fiber axis. The formation of mineralized nodules was observed on the films by Alizarin red S staining. These results suggest that the presence of basalt fibers does not noticeably affect osteoblastic behavior and the designed composites are osteoblast compatible. It is concluded that basalt fibers, as reinforcing fibers, may have promising applications in hard tissue repair.

  20. Physicochemical evaluation of silica-glass fiber reinforced polymers for prosthodontic applications.

    PubMed

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

    2005-06-01

    This investigation was designed to formulate silica-glass fiber reinforced polymeric materials. Fused silica-glass fibers were chosen for the study. They were heat-treated at various temperatures (500 degrees C, 800 degrees C and 1100 degrees C), silanized, sized and incorporated in two modified resin mixtures (A and B). The flexural properties in dry and wet conditions were tested and statistically analyzed, and the content of residual methyl methacrylate (MMA) monomer, dimensional changes with temperature, water sorption and solubility were determined. Woven fibers [36.9% (wt/wt)], heat-treated at 500 degrees C, gave the highest strength values for the polymeric composites (an ultimate transverse strength of 200 Mpa and a flexural modulus of 10 GPa) compared with the fibers heat-treated at other temperatures. There was no statistically significant difference in the measured flexural properties between resins A and B regarding fiber treatment and water storage time. These fiber composites had a small quantity of residual MMA content [0.37 +/- 0.007% (wt/wt)] and very low water solubility, indicating good biocompatibility. It was suggested that silica-glass fibers could be used for reinforcement as a result of their anticipated good qualities in aqueous environments, such as the oral environment.

  1. Fatigue Hysteresis of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Li, Longbiao

    2016-02-01

    When the fiber-reinforced ceramic-matrix composites (CMCs) are first loading to fatigue peak stress, matrix multicracking and fiber/matrix interface debonding occur. Under fatigue loading, the stress-strain hysteresis loops appear as fiber slipping relative to matrix in the interface debonded region upon unloading/reloading. Due to interface wear at room temperature or interface oxidation at elevated temperature, the interface shear stress degredes with increase of the number of applied cycles, leading to the evolution of the shape, location and area of stress-strain hysteresis loops. The evolution characteristics of fatigue hysteresis loss energy in different types of fiber-reinforced CMCs, i.e., unidirectional, cross-ply, 2D and 2.5D woven, have been investigated. The relationships between the fatigue hysteresis loss energy, stress-strain hysteresis loops, interface frictional slip, interface shear stress and interface radial thermal residual stress, matrix stochastic cracking and fatigue peak stress of fiber-reinforced CMCs have been established.

  2. Smart damping of laminated fuzzy fiber reinforced composite shells using 1-3 piezoelectric composites

    NASA Astrophysics Data System (ADS)

    Kundalwal, S. I.; Kumar, R. Suresh; Ray, M. C.

    2013-10-01

    This paper deals with the investigation of active constrained layer damping (ACLD) of smart laminated continuous fuzzy fiber reinforced composite (FFRC) shells. The distinct constructional feature of a novel FFRC is that the uniformly spaced short carbon nanotubes (CNTs) are radially grown on the circumferential surfaces of the continuous carbon fiber reinforcements. The constraining layer of the ACLD treatment is considered to be made of vertically/obliquely reinforced 1-3 piezoelectric composite materials. A finite element (FE) model is developed for the laminated FFRC shells integrated with the two patches of the ACLD treatment to investigate the damping characteristics of the laminated FFRC shells. The effect of variation of the orientation angle of the piezoelectric fibers on the damping characteristics of the laminated FFRC shells has been studied when the piezoelectric fibers are coplanar with either of the two mutually orthogonal vertical planes of the piezoelectric composite layer. It is revealed that radial growth of CNTs on the circumferential surfaces of the carbon fibers enhances the attenuation of the amplitude of vibrations and the natural frequencies of the laminated FFRC shells over those of laminated base composite shells without CNTs.

  3. Poly(ɛ-caprolactone) composites reinforced by biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) fiber.

    PubMed

    Ju, Dandan; Han, Lijing; Li, Fan; Chen, Shan; Dong, Lisong

    2014-06-01

    Biodegradable and biosourced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fiber was used as a reinforcing agent, and environment friendly poly(ɛ-caprolactone) (PCL) composites were prepared by melt compounding. The mechanical properties, rheological properties, and enzymatic degradation of the PCL composites were investigated in detail. With the addition of PHBV fibers, the PCL composites showed increased tensile yielding strength and modulus. Especially, the storage modulus from the results of dynamic mechanical analysis was increased significantly, suggesting that PCL was obviously reinforced by adding PHBV fibers. With increasing the PHBV fiber content, the complex viscosity and modulus of PCL increased, especially at low frequencies, indicating that a network structure was formed in the composites. The network structure resulted in evident solid-like response due to the restriction of the chain mobility of PCL matrix, which was further confirmed by the Han and Cole-Cole plots. The morphology, evaluated by scanning electron microscopy, indicated PCL and PHBV fiber were not highly incompatible and the interfacial adhesion was good, which was beneficial to the reinforcement effect. The biodegradability of the PCL was significantly promoted after composites preparation. Such studies are of great interest in the development of environment friendly composites from biodegradable polymers.

  4. 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).

  5. Compressive strength of fiber-reinforced composite materials

    NASA Technical Reports Server (NTRS)

    Davis, J. G., Jr.

    1975-01-01

    Results of an experimental and analytical investigation of the compressive strength of unidirectional boron-epoxy composite material are presented. Observation of fiber coordinates in a boron-epoxy composite indicates that the fibers contain initial curvature. Combined axial compression and torsion tests were conducted on boron-epoxy tubes and it was shown that the shear modulus is a function of axial compressive stress. An analytical model which includes initial curvature in the fibers and permits an estimate of the effect of curvature on compressive strength is proposed. Two modes of failure which may result from the application of axial compressive stress are analyzed - delamination and shear instability. Based on tests and analysis, failure of boron-epoxy under axial compressive load is due to shear instability.

  6. Exposure Assessment of a High-energy Tensile Test With Large Carbon Fiber Reinforced Polymer Cables.

    PubMed

    Schlagenhauf, Lukas; Kuo, Yu-Ying; Michel, Silvain; Terrasi, Giovanni; Wang, Jing

    2015-01-01

    This study investigated the particle and fiber release from two carbon fiber reinforced polymer cables that underwent high-energy tensile tests until rupture. The failing event was the source of a large amount of dust whereof a part was suspected to be containing possibly respirable fibers that could cause adverse health effects. The released fibers were suspected to migrate through small openings to the experiment control room and also to an adjacent machine hall where workers were active. To investigate the fiber release and exposure risk of the affected workers, the generated particles were measured with aerosol devices to obtain the particle size and particle concentrations. Furthermore, particles were collected on filter samples to investigate the particle shape and the fiber concentration. Three situations were monitored for the control room and the machine hall: the background concentrations, the impact of the cable failure, and the venting of the exposed rooms afterward. The results showed four important findings: The cable failure caused the release of respirable fibers with diameters below 3 μm and an average length of 13.9 μm; the released particles did migrate to the control room and to the machine hall; the measured peak fiber concentration of 0.76 fibers/cm(3) and the overall fiber concentration of 0.07 fibers/cm(3) in the control room were below the Permissible Exposure Limit (PEL) for fibers without indication of carcinogenicity; and the venting of the rooms was fast and effective. Even though respirable fibers were released, the low fiber concentration and effective venting indicated that the suspected health risks from the experiment on the affected workers was low. However, the effect of long-term exposure is not known therefore additional control measures are recommended.

  7. The effect of different fiber reinforcements on flexural strength of provisional restorative resins: an in-vitro study

    PubMed Central

    Parkhedkar, Rambhau D.; Mowade, Tushar Krishnarao

    2012-01-01

    PURPOSE The aim of this study was to compare the flexural strength of polymethyl methacrylate (PMMA) and bis-acryl composite resin reinforced with polyethylene and glass fibers. MATERIALS AND METHODS Three groups of rectangular test specimens (n = 15) of each of the two resin/fiber reinforcement were prepared for flexural strength test and unreinforced group served as the control. Specimens were loaded in a universal testing machine until fracture. The mean flexural strengths (MPa) was compared by one way ANOVA test, followed by Scheffe analysis, using a significance level of 0.05. Flexural strength between fiber-reinforced resin groups were compared by independent samples t-test. RESULTS For control groups, the flexural strength for PMMA (215.53 MPa) was significantly lower than for bis-acryl composite resin (240.09 MPa). Glass fiber reinforcement produced significantly higher flexural strength for both PMMA (267.01 MPa) and bis-acryl composite resin (305.65 MPa), but the polyethylene fibers showed no significant difference (PMMA resin-218.55 MPa and bis-acryl composite resin-241.66 MPa). Among the reinforced groups, silane impregnated glass fibers showed highest flexural strength for bis-acryl composite resin (305.65 MPa). CONCLUSION Of two fiber reinforcement methods evaluated, glass fiber reinforcement for the PMMA resin and bis-acryl composite resin materials produced highest flexural strength. Clinical implications On the basis of this in-vitro study, the use of glass and polyethylene fibers may be an effective way to reinforce provisional restorative resins. When esthetics and space are of concern, glass fiber seems to be the most appropriate method for reinforcing provisional restorative resins. PMID:22439093

  8. Fabrication of fiber-reinforced composites by chemical vapor infiltration

    SciTech Connect

    Matlin, W.M.; Stinton, D.P.; Besmann, T.M.

    1995-08-01

    A two-step forced chemical vapor infiltration process was developed that reduced infiltration times for 4.45 cm dia. by 1.27 cm thick Nicalon{sup +} fiber preforms by two thirds while maintaining final densities near 90 %. In the first stage of the process, micro-voids within fiber bundles in the cloth were uniformly infiltrated throughout the preform. In the second stage, the deposition rate was increased to more rapidly fill the macro-voids between bundles within the cloth and between layers of cloth. By varying the thermal gradient across the preform uniform infiltration rates were maintained and high final densities achieved.

  9. Friction and wear behavior of graphite fiber reinforced polymide composites

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.; Sliney, H. E.

    1977-01-01

    The friction and wear rate characteristics of 50/50 (weight percent) graphite fiber polyimide composites were studied by sliding metallic hemispherically tipped riders against disks made from the composites. Two different polyimides and two different graphite fibers were evaluated. Also studied were such variables as the effect of moisture in an air atmosphere; the effect of temperature; and the effect of different sliding speeds. In general, wear to the the metallic riders was negligible, and composite wear increased at a constant rate as a function of number of sliding cycles.

  10. Mechanical properties of long carbon fiber reinforced thermoplastic (LFT) at elevated temperature

    NASA Astrophysics Data System (ADS)

    Wang, Qiushi

    Long fiber reinforced thermoplastics (LFT) possess high specific modulus and strength, superior damage tolerance and fracture toughness and have found increasing use in transportation, military, and aerospace applications. However, one of the impediments to utilizing these materials is the lack of performance data in harsh conditions, especially at elevated temperature. In order to quantify the effect of temperature on the mechanical properties of carbon fiber reinforced thermoplastic composites, carbon fiber PAA composite plates containing 20% and 30% carbon fiber were produced using extrusion/compression molding process and tested at three representative temperatures, room temperature (RT 26°C), middle temperature (MID 60°C) and glass transition temperature (Tg 80°C). A heating chamber was designed and fabricated for the testing at elevated temperature. As temperature increases, flexural modulus, flexural strength, tensile modulus and tensile strength decrease. The highest reduction observed in stiffness (modulus) values of 30% CF/PAA at Tg in the 00 orientation is 75%. The reduction values were larger for the transverse (perpendicular to flow direction) samples than the longitudinal (flow direction) samples. The property reduction in 30% CF/PAA is larger than 20% CF/PAA. Furthermore, an innovative method was developed to calculate the fiber content in carbon fiber reinforced composites by burning off the neat resin and sample in a tube furnace. This method was proved to be accurate (within 1.5 wt. % deviation) by using burning off data obtained from CF/Epoxy and CF/Vinyl Ester samples. 20% and 30% carbon/PAA samples were burned off and carbon fiber content was obtained using this method. The results of the present study will be helpful in determining the end-user applications of these composite materials. Keywords: Long Carbon Fibers, Elevated Temperature, Mechanical Properties, Burn off Test.

  11. Multiscale carbon nanotube-carbon fiber reinforcement for advanced epoxy composites.

    PubMed

    Bekyarova, E; Thostenson, E T; Yu, A; Kim, H; Gao, J; Tang, J; Hahn, H T; Chou, T-W; Itkis, M E; Haddon, R C

    2007-03-27

    We report an approach to the development of advanced structural composites based on engineered multiscale carbon nanotube-carbon fiber reinforcement. Electrophoresis was utilized for the selective deposition of multi- and single-walled carbon nanotubes (CNTs) on woven carbon fabric. The CNT-coated carbon fabric panels were subsequently infiltrated with epoxy resin using vacuum-assisted resin transfer molding (VARTM) to fabricate multiscale hybrid composites in which the nanotubes were completely integrated into the fiber bundles and reinforced the matrix-rich regions. The carbon nanotube/carbon fabric/epoxy composites showed approximately 30% enhancement of the interlaminar shear strength as compared to that of carbon fiber/epoxy composites without carbon nanotubes and demonstrate significantly improved out-of-plane electrical conductivity.

  12. Fracture mechanics in fiber reinforced composite materials, taking as examples B/A1 and CRFP

    NASA Technical Reports Server (NTRS)

    Peters, P. W. M.

    1982-01-01

    The validity of linear elastic fracture mechanics and other fracture criteria was investigated with laminates of boron fiber reinforced aluminum (R/A1) and of carbon fiber reinforced epoxide (CFRP). Cracks are assessed by fracture strength Kc or Kmax (critical or maximum value of the stress intensity factor). The Whitney and Nuismer point stress criterion and average stress criterion often show that Kmax of fiber composite materials increases with increasing crack length; however, for R/A1 and CFRP the curve showing fracture strength as a function of crack length is only applicable in a small domain. For R/A1, the reason is clearly the extension of the plastic zone (or the damage zone n the case of CFRP) which cannot be described with a stress intensity factor.

  13. Model of brittle matrix composite toughening based on discrete fiber reinforcement

    NASA Technical Reports Server (NTRS)

    Rubinstein, Asher A.

    1992-01-01

    An analytical approach for the analysis of the effectiveness of fiber reinforcement in brittle matrix composites is presented. The analytical method allows consideration of discrete fiber distribution and examination of the development of crack growth parameters on microscale. The problem associated with the bridging zone development is addressed here; therefore, the bridging zone is considered to be smaller than the main preexisting crack, and the small scale approach is used. The mechanics of the reinforcement is accurately accounted for in the process zone of a growing crack. Closed form solutions characterizing the initial failure process are presented for linear and nonlinear force - fiber pullout displacement relationships. The implicit exact solution for the extended bridging zone is presented as well.

  14. Design and realization a skiff racing boat hull made of natural fibers reinforced composite

    NASA Astrophysics Data System (ADS)

    Collotta, M.; Solazzi, L.; Pandini, S.; Tomasoni, G.; Alberti, M.; Donzella, G.

    2016-05-01

    This paper discusses the development of a racing boat with an hull made of a composite material reinforced by natural fibers. In particular, we report here the design and realization of the boat hull, the assessment of its mechanical performance by means of a computer assisted simulation, and the cost analysis to assess the economic sustainability of the new composite developed. The results have shown that the new composite has a performance comparable with conventional glass fiber reinforced composites employed for the realization of this type of boat, accordingly to the technology employed and the lamination sequence adopted. Moreover, the FEM analysis performed over the skiff of the designed and constructed boat has demonstrated a successful choice of the material for real application, as it was later confirmed by the good performance of the boat in water. Finally, the cost analysis highlighted the economic sustainability of the new composite, allowing a cost saving of over 28% with respect to carbon fiber composites.

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

    SciTech Connect

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

    2008-07-08

    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. Finally, effects of retrofitting are evaluated and some suggestions presented.

  16. Fiber-reinforced Composite for Chairside Replacement of Anterior Teeth: A Case Report

    PubMed Central

    Garoushi, S; Vallittu, PK; Lassila, LVJ

    2008-01-01

    A variety of therapeutic modalities, from implant to conventional Maryland prosthesis, can be used for the replacement of a missing anterior tooth. Whenever a minimal tooth reduction is preferred, a fiber reinforced composite (FRC) prosthesis could be a good alternative to conventional prosthetic techniques, chiefly as temporary restoration before making a final decision on the treatment. The purpose of this case report is to describe the clinical procedure of fabricating anterior chairside FRC prosthesis with pre-impregnated unidirectional E-glass fibers and veneered particulate filler composite. Fiber-reinforced composite in combination with adhesive technology appears to be a promising treatment option for replacing missing teeth. However, further and long-term clinical investigation will be required to provide additional information on the survival of directly-bonded anterior fixed prosthesis made with FRC systems. PMID:21499473

  17. The importance of material structure in the laser cutting of glass fiber reinforced plastic composites

    SciTech Connect

    Caprino, G. . Dipt. di Ingegneria dei Materiali e della Produzione); Tagliaferri, V. . Istituto di Ingegneria Meccanica); Covelli, L. )

    1995-01-01

    A previously proposed micromechanical formula, aiming to predict the vaporization energy Q[sub v] of composite materials as a function of fiber and matrix properties and fiber volume ratio, was assessed. The experimental data, obtained on glass fiber reinforced plastic panels with different fiber contents cut by a medium power CO[sub 2] cw laser, were treated according to a procedure previously suggested, in order to evaluate Q[sub v]. An excellent agreement was found between experimental and theoretical Q[sub v] values. Theory was then used to predict the response to laser cutting of a composite material with a fiber content varying along the thickness. The theoretical predictions indicated that, in this case, the interpretation of the experimental results may be misleading, bringing to errors in the evaluation of the material thermal properties, or in the prediction of the kerf depth. Some experimental data were obtained, confirming the theoretical findings.

  18. Mechanical behavior of fiber reinforced SiC/RBSN ceramic matrix composites: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Chulya, Abhisak; Gyekenyesi, John P.; Bhatt, Ramakrishna T.

    1991-01-01

    The mechanical behavior of continuous fiber reinforced SiC/RBSN (Reaction Bonded Silicon Nitride) composites with various fiber contents is evaluated. Both catastrophic and noncatastrophic failures are observed in tensile specimens. Damage and failure mechanisms are identified via in-situ monitoring using NDE (nondestructive evaluation) techniques through the loading history. Effects of fiber/matrix interface debonding (splitting) parallel to fibers are discussed. Statistical failure behavior of fibers is also observed, especially when the interface is weak. Micromechanical models incorporating residual stresses to calculate the critical matrix cracking strength, ultimate strength, and work of pull-out are reviewed and used to predict composite response. For selected test problems, experimental measurements are compared to analytical predictions.

  19. Effect of Thermal Cycling on the Tensile Behavior of Polymer Composites Reinforced by Basalt and Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Khalili, S. Mohammad Reza; Najafi, Moslem; Eslami-Farsani, Reza

    2017-01-01

    The aim of the present work was to investigate the effect of thermal cycling on the tensile behavior of three types of polymer-matrix composites — a phenolic resin reinforced with woven basalt fibers, woven carbon fibers, and hybrid basalt and carbon fibers — in an ambient environment. For this purpose, tensile tests were performed on specimens previously subjected to a certain number of thermal cycles. The ultimate tensile strength of the specimen reinforced with woven basalt fibers had by 5% after thermal cycling, but the strength of the specimen with woven carbon fibers had reduced to a value by 11% higher than that before thermal cycling.

  20. Simulation of a Novel Joining Process for Fiber-Reinforced Thermoplastic Composites and Metallic Components

    NASA Astrophysics Data System (ADS)

    Gude, M.; Freund, A.; Vogel, C.; Kupfer, R.

    2017-01-01

    In this study, a new joining technology to produce hybrid structures with continuous-fiber-reinforced thermoplastics and metallic components is presented adapting the concept of classical clinching for thermoplastic composites. To demonstrate the capability of the thermoclinching process, prototypic joints were manufactured using an experimental joining installation developed. Nondestructive and destructive analyses of the thermoclinched joints showed that a relocation of the reinforcement into the neck and head area of the joining zone could be achieved. For a first estimation of the maximum load-carrying capacity of the joints, single-lap specimens with both reinforced and nonreinforced thermoplastics were manufactured and tested, revealing up to 50% higher failure loads of the reinforced joints. To understand the local material configuration and to achieve a defined and adjustable fabric structure in the head area of the joint, further analyses with regard to material- and tool-side conditions of the joining zone are necessary.