Carbon Fiber Sheets Research Articles

Impact of MPL Thickness on Water Management of PEMFC By Synchrotron X-ray Radiography

The polymer electrolyte membrane fuel cell (PEMFC) is an efficient and clean energy conversion device. The performance of PEMFCs at high power operation is governed by product water management. The gas diffusion layer (GDL), a porous carbon fiber sheet, is sandwiched between a catalyst layer and a flow field, providing diffusive pathways for reactant gases and product water. A transient microporous layer (MPL) characterized by sub-micron size pores and hydrophobic contents applied on the GDL or catalyst layer is known to extend limiting current density. Past research [1] has shown that there exists an optimal thickness of MPL. However, the effect of varying MPL thickness has not been studied by visual inspection.Our research group has successfully investigated liquid water dynamic and distribution in an operating PEMFC using synchrotron radiography [2-3]. For this study, a miniature fuel cell with an active area of 0.48cm2and 0.2mm channel and rib width was designed for improved image quality. MPLs of varying thickness (no MPL, 50μm, 100μm, and 150μm) were coated on TGP-H-60 (Toray Industries Inc.). Each fuel cell was operated according to a pre-determined testing scheme on a Scribner 850e fuel cell testing station (Scribner Inc.). Visualizations were performed at the Biomedical Imaging and Therapy Bending Magnet (05B1-1) beamline at Canadian Light Source Inc. (Saskatoon, Canada). Spatial and temporal resolutions were approximately 10μm and 0.3fps, respectively. Image processing was carried out according to the Beer-Lambert law. The processed image provides information on liquid water profile across components of the fuel cell (Figures 1 and 2). For each types of GDL, liquid water content at the interfaces and within microstructures will be analyzed to isolate effect of MPL thickness on water distribution and performance of the fuel cell.

The Anti-Bending Performance Study of Loaded Continuous Beam that Strengthened with Prestressed Laterally Bonded Carbon Fiber Sheets

We studied the strengthening performance of prestressed laterally bonded carbon fiber sheets (CFS) to two-span continuous beams in this paper, which included one unstrengthened beam, two non-prestressed laterally bonded CFS strengthening beams, and four prestressed laterally bonded CFS strengthening beams, and all of them were sticked with CFS on different styles on tension part of lateral beam. We discussed the stress and deformation of laterally bonded CFS strengthened continuous beams under different initial load cases and different prestressed impact, and studied the influence of initial load and prestressing to reinforcement effect. The results showed that the size of initial load and prestressing would affect the reinforcement effect of laterally bonded CFS to continuous beams; The smaller initial load, the better reinforcement effect; The reinforcement effect to continuous beams of prestressed laterally bonded CFS was better than the non-prestressed laterally bonded CFS. Corresponding to latter, the former also owned better deformation performance, less cracks number and width.

The Shear Capacity Calculation of Steel Reinforcement High-Strength Concrete Short Columns Restrained with FRP

This article aims to study the calculation for shear capacity of SRHC (Steel Reinforced High-Strength Concrete) members restrained with CFS (Carbon Fiber Sheet). Experimental study, theoretical analysis and calculation simulating are integrated in this article for the research of the shear failure characteristics and effect of various parameters on their behavior of SRHC members restrained with SFC on the basis of existed SRHC members tested results. The shear strength formula of steel reinforcement high-strength concrete short columns restrained with CFS is put forward, which based on the superposed strength method. This method on the basis of the load-deformation process of CFS is similar to hooping. The results indicate that the shear capacity of SRHC columns restrained with CFS is higher than SRHC columns. And, due to the axial compression ratio, shear span ratio and the amount of reinforcement influence the shear capacity of the FRP materials. So, these three kinds of factors are also the influencing factors of shear capacity of SRHC members restrained with CFS. The effect of the internal concrete restrained with CFS is good because of the function of CFS is equal to hooping and the strain of CFS is bigger than the strain of steel, so this simple calculation method is safe , which may be useful for further study and engineering design.

Semiempirical Methodology for Estimating the Service Life of Concrete Deck Panels Strengthened with Fiber-Reinforced Polymer

Deterioration of concrete bridge decks affects their durability, safety, and function. It is therefore necessary to conduct structural rehabilitation of damaged concrete decks by strengthening them with fiber-reinforced polymer. Of the recent studies on the strengthened structures, most have focused on static behavior; only a few studies have investigated fatigue behavior. Accurate analysis of fatigue in concrete deck performance requires a more realistic simulated moving load. This study developed a theoretical live-load model to reflect the effect of moving vehicle loads, based on a statistical approach to the measurement of real traffic loads over various time periods in Korea. It assessed the fatigue life and strengthening effect of bridge decks strengthened with either carbon fiber sheets or grid carbon fiber polymer plastic using probabilistic and reliability analyses. It used extrapolations and simulations to derive maximum load effects for time periods ranging from 1 day to 75 years. Limited fatigue tests were conducted and probabilistic and reliability analyses were carried out on the strengthened concrete bridge deck specimens to predict the extended fatigue life. Analysis results indicated that strengthened concrete decks provide sufficient resistance against increasing truck loads during the service life of a bridge.

Experimental Research on Fireproofing Measure of Slabs Strengthened by Carbon Fiber Sheet Bonded with Inorganic Adhesive

Because of high temperature above 1000°C on fire, and Oxidation of carbon fiber at high temperature, fireproofing measure should be make to take advantage of inorganic adhesive for slabs strengthened by carbon fiber sheet bonded with the adhesive. The problem of which fireproofing material should be choose and how to make fireproofing measure needs to resolve. Fireproofing test is make for slabs strengthened by carbon fiber sheet bonded with the adhesive protected by Thick-typed Fireproof Coating for steel structure (TFCSS) and Thick-typed Fireproof Coating for tunnel (TFCT). Typical damage state of the two typical coating is compared during and after fire, Temperature field of slab specimen is analyzed, and fireproofing effect is compared. The test results indicate that, steel wire mesh in the middle of coating layer can prevent coating from falling fully, so steel wire mesh is necessary for fireproofing coat which is not too thick. under the protection of fireproof coating with proper construction, TFCT and TFCSS can supply effective fireproofing protection for carbon fiber sheet, but the former is inferior to the latter because the latter is easier to drop and crack in fire. So, TFCT with steel wire mesh can supply the most effective protection for slabs strengthened by carbon fiber sheet bonded with the adhesive.

Drying on the Board- and Boxed Heart Squares-larch Lumbers within an Opaque Solar Drying House Covered by a Composite Surface

Two sorts of lumber drying house covered by a composite surface consisting of three layer transparent films and a carbon-fibre sheet (CF-sheet; looks like a semi-opaque) were invented and developed. One of them was built in Ashoro-cho, the eastern part of Hokkaido, Japan (the first proving site), and the other was built in Asahikawa-shi, the central part of Hokkaido (the second proving site). The dimension of each drying houses is a frontage of 4.5 m, depth of 5.0 m and height of 3.4 m (the 1st site) and the same frontage and depth as the former, but height of 3.8 m (the 2nd site), respectively. Two types of models of the drying house (East-West type and South-North-type) were desinged. The former is shaped like a half Quonset hut and the latter a just Quonset hut. All of the surfaces including the roof and walls except for a north wall of both models are covered by a composite surface. The composite surface is specially consisted by a triple transparent film from upper side and a CF-sheet to bottom side between which there are a few space of air layers. As a result of mutual effect of a spectral radiation properties of the films and the CF-sheet, a total solar radiation incident upon the drying house with cubic body composed of multi-surface from all the sky globally, can be collected into the house as solar rays volumetrically, converted into infrared radiation and trapped inside the drying house as solar heat passively, without any electric power. Moreover, the moist air inside the house being evaporated when drying green lumber can be naturally exhausted through two insulated cylinders (chimney) outside the drying house according to a principle of the thermo-siphon. From these reasons, “An opaque solar lumber drying house covered by a composite surface consisting of a triple-transparent film and a CF-sheet” could be called “A fully passive solar lumber drying house” in other word.In this paper, after explained the principle of drying mechanism due to solar radiation and heat rays, the experimental procedures and the results at the proving test, on a board-larch lumber at the 1st proving site and a boxed heart squares-larch lumber for pillar material at the 2nd proving site, were described and discussed thoroughly.

補強量の違いが耐爆補強効果に及ぼす影響

When designing blast-resistant reinforced concrete (RC) structures, it is important to reduce spall damage due to reflected tensile stress waves. In this study, to devise a blast-resistant strengthening method for existing RC slabs, contact detonation tests using 200 g of explosive charges were conducted on RC slabs with rear surfaces strengthened with continuous fiber sheets/meshes. High-strength carbon fiber (HSCF) and high-modulus carbon fiber (HMCF) sheets were employed to strengthen 75-mm-thick RC slabs, and the number of layers used for strengthening them was varied between 2, 4, and 6 layers. Two types of carbon fiber reinforced plastic (CFRP) meshes, in which the weight per unit area of carbon fibers was varied between 215 and 430 g/m2, were also used to strengthen 100-mm-thick RC slabs. The results showed that the spall failure of the 75-mm-thick RC slabs could be prevented by bonding more than four HSCF sheets onto the rear side of the slab; however, the HMCF sheets had no effect on the blast resistance of the slabs because of fiber rupture. Further, the spall failure of the 100-mm-thick RC slabs could be prevented by bonding the CFRP meshes with fibers 430 g/m2 in volume. On the basis of the test results, the criteria for fiber rupture in CF sheets due to detonation loading was discussed in terms of the fracture energy of the sheets and the modified-scaled concrete thickness of the slab. Furthermore, high-speed photography was employed to investigate the spall failure process of each strengthened slab.

Combination of Carbon Fibre Sheet Moulding Compound and Prepreg Compression Moulding in Aerospace Industry

The demand for fuel efficient aircraft led to the development of innovative lightweight constructions and the use of lightweight materials, such as carbon fibre reinforced plastics. In the same manner competences in new production technologies have been built up in the aerospace industry. However, current processes for producing lightweight composites with an excellent mechanical performance cause high costs and long process cycles in comparison with approved metal processes. Furthermore the used raw materials, such as carbon fibres and resin, are very expensive. In contrast to these technologies Sheet Moulding Compound is characterised by a very high productivity, excellent part reproducibility, cost efficiency and the possibility to realise parts with complex geometries and integrated functions, e.g. inserts or colouring. The biggest disadvantage of Sheet Moulding Compound parts is a low level of stiffness and strength because of a low fibre-volume fraction, a short fibre length and isotropic fibre distribution. In this context the combination of Sheet Moulding Compound and Prepreg compression moulding in an one-shot compression moulding and curing process merges the advantages of both materials to create load-bearing and autoclave-quality parts without an autoclave. In the following article, this new technology and its potential will be presented. This paper will also deal with the resulting material characteristics.

Analysis on Fire-Resistance Performance of Beams Strengthened by Carbon Fiber Sheet Bonded with Inorganic Adhesive

Fire-resistance performance of beams can be improved if the beam strengthened by carbon fiber sheet bonded with inorganic adhesive instead of organic epoxy adhesive with low softening temperature. However, Fire-resistance performance of the strengthened beams is not understood fully. Considering this issue, finite element analysis is done. Stating from building valid model of finite element, computing results are compared with experimental results, and rationality of the model is verified. Then plenty of parameter analysis is done. Effect of some parameters, such as Range of carrying capacity increase by sheet, reinforcement ratio, load ratio to carrying capacity and width of section, on fire-resistance performance of the strengthened beams is analysis. The results demonstrates that reinforcement ratio and load ratio to carrying capacity is the main factors influencing fire-resistance performance of the beam strengthened by carbon fiber sheet bonded with inorganic adhesive, While, range of carrying capacity increase by sheet and width of section have little influence on it. Beams, strengthened by carbon fiber sheet bonded with inorganic adhesive, and protected by Thick-typed Fireproof Coating, perform good fire behavior.

Astudy on optimumdesignmethod of repair and reinforcementmethod using carbon fiber sheets for corroded web in steel girder bridge

Astudy on optimumdesignmethod of repair and reinforcementmethod using carbon fiber sheets for corroded web in steel girder bridge

The effect of elevated temperature on the bond between high modulus carbon fibre-reinforced polymer sheet and steel

The technique of strengthening steel structures with carbon fibre-reinforced polymer (CFRP) has attracted growing attention in research field and in practice, and thus, its environmental durability is of high importance. This paper describes an investigation on the bond characteristics between high modulus CFRP sheets and steel plates under elevated temperature exposures. Tensile tests were carried out on CFRP/steel plate double strap joints at different temperatures (20, 40 and 50 degreesC) that represent the usually encountered conditions for civil infrastructure. High modulus (640 GPa) unidirectional carbon fibre sheets were applied by wet lay-up fabrication method. The fracture surfaces of the failed specimens were studied using a scanning electron microscope and the failure mechanisms were discussed. It was found that the ultimate load decreased significantly when the test temperature was above the glass transition temperature of the adhesive. Larger effective bond lengths were found for the joints tested at the glass transition temperature. It is obvious that the short-term thermal exposure has little effect on their failure patterns. All the specimens failed by fibre breakage at the joint and decohesion accompanied some joints with very short bond length.

The Effect of Elevated Temperature on the Bond Between High Modulus Carbon Fibre-Reinforced Polymer Sheet and Steel

The technique of strengthening steel structures with carbon fibre-reinforced polymer (CFRP) has attracted growing attention in research field and in practice, and thus, its environmental durability is of high importance. This paper describes an investigation on the bond characteristics between high modulus CFRP sheets and steel plates under elevated temperature exposures. Tensile tests were carried out on CFRP/steel plate double strap joints at different temperatures (20,40 and 50 °C) that represent the usually encountered conditions for civil infrastructure. High modulus (640 GPa) unidirectional carbon fibre sheets were applied by wet lay-up fabrication method. The fracture surfaces of the failed specimens were studied using a scanning electron microscope and the failure mechanisms were discussed. It was found that the ultimate load decreased significantly when the test temperature was above the glass transition temperature of the adhesive. Larger effective bond lengths were found for the joints tested at the glass transition temperature. It is obvious that the short-term thermal exposure has little effect on their failure patterns. All the specimens failed by fibre breakage at the joint and decohesion accompanied some joints with very short bond length.

Tensile behavior of FRP and hybrid FRP sheets in freeze–thaw cycling environments

This study presents the results of an experimental investigation of the freeze–thaw (FT) resistance, including the hybridization of fibers, of carbon, basalt and glass fiber-reinforced polymer (CFRP, BFRP and GFRP) sheets commonly used in civil engineering practice. Coupon tests were conducted to investigate the tensile properties of FRP sheets and their corresponding epoxy resins and dry fiber sheets after up to 300 FT cycles. Sustained loading was included in the testing to reflect the behavior of FRP sheets in real structures. The test results indicate that (1) BFRP and hybrid FRP sheets have better FT resistance than CFRP and GFRP sheets, and the hybridization of fibers can contribute to the stability of the tensile properties of these materials after FT exposure; (2) the tensile properties of the resin matrix deteriorate significantly with increasing FT cycles; (3) further degradation of the tensile properties of FRP sheets is caused by sustained loading during FT cycling; and (4) the tensile behavior of dry glass fiber sheets is more sensitive to FT cycling than dry carbon and basalt fiber sheets. Lastly, the degradation mechanism of FRP sheets in FT environments is discussed.

Experimental Research on Fireproofing Measure of Beams Strengthened by Carbon Fiber Sheet Bonded with Inorganic Adhesive

Because of high temperature above 1000°C on fire, and Oxidation of carbon fiber at high temperature, fireproofing measure should be make to take advantage of the inorganic adhesive for beams strengthened by carbon fiber sheet bonded with the adhesive. The problem of which fireproofing material should be choose and how to make fireproofing measure needs to resolve. Fireproofing test is make for beams strengthened by carbon fiber sheet bonded with the adhesive protected by Thick-typed Fireproof Coating for steel structure (TFCSS) and Thick-typed Fireproof Coating for tunnel (TFCT). Typical damage state of the two typical coating is compared on and after fire, Temperature field of specimen is analyzed, and fireproofing effect is compared. The test results indicate that, under the protection of fireproof coating with proper structure, TFCT and TFCSS can supply effective fireproofing protection for carbon fiber sheet, but the former is inferior to the latter because the latter is easier to drop and crack in fire

Analysis on Fire-Resistance Performance of Slabs Strengthened by Carbon Fiber Sheet Bonded with Inorganic Adhesive

Fire-resistance performance of slabs can be improved if the slab strengthened by carbon fiber sheet bonded with inorganic adhesive instead of organic epoxy adhesive with low softening temperature. However, Fire-resistance performance of the strengthened slabs is not understood fully. Considering this issue, finite element analysis is done. Stating from building valid model of finite element, computing results are compared with experimental results, and rationality of the model is verified. Then plenty of parameter analysis is done. Effect of some parameters, such as range of carrying capacity increase by sheet, reinforcement ratio, load ratio to carrying capacity and thickness of slab, on fire-resistance performance of the strengthened slab is analysis. The results demonstrate that thickness of slab is the main factors influencing fire-resistance performance of the slab strengthened by carbon fiber sheet bonded with inorganic adhesive. While, range of carrying capacity increase by sheet, width of section and load ratio to carrying capacity have little influence on it. Slabs, strengthened by carbon fiber sheet bonded with inorganic adhesive, and protected by Thick-typed Fireproof Coating, perform good fire behavior.

긴급시공이 가능한 FRP 내진보강재로 보강된 기둥의 내진성능평가 실험

최근 발생한 대규모 지진으로 구조물의 내진보강에 대한 사회적 관심도가 높아지고 있다. 특히 내진설계가 반영되지 않은 기둥의 경우 지진에 의한 횡하중을 저항하지 못하고, 취성적인 파괴가 유발되어 구조물 전체적 붕괴를 유발할 수 있다. 따라서 빠른 시간내에 보강이 가능하면서 기둥에 손상을 주지 않는 기존의 보강법과 구별되는 응급 보강법이 필요하다. 과거에는 기둥 보강법으로 단면 증설법과 강판보강법 등이 개발되어 현장에 적용되었지만, 최근에는 FRP (Fiber Reinforced Polymer)의 장점을 활용한 탄소섬유시트공법이 많이 사용되고 있다. 본 연구에서는 긴급시공이 가능한 체결식 FRP 내진보강재를 사용한 구조물의 내진성능보강효과를 검토하고자 하였다. 검토를 위하여 실제 구조물의 축소모델의 철근콘크리트 시험체를 제작하고 횡방향 변위하중을 가력하였다. FRP 내진보강재를 이용한 내진보강시공 후 실내시험을 통하여 내진성능을 평가하였다. 그 결과 개발된 보강재의 철근콘크리트 구조물에 보강 시, 내진성능이 향상됨을 확인하였다. As increasing number of large-size earthquake, the social interest of seismic retrofitting of RC structure is growing. Especially, the RC columns that are not reflected seismic design can not resist lateral loads by the earthquake. The brittle fracture of Non-seismic designed columns lead to full collapse of the building. Thus, the emergency columns reinforcement method is needed. That have a fast construction time, do not cause damage to the column. In the past, cross-sectional expansion method, a steel plate reinforcing method is applied mainly, but in recent years, carbon fiber sheet taking advantage of FRP (Fiber Reinforced Polymer) is widely used. In this study, retrofitting effect of seismic performance of FRP seismic reinforcement, which is possible to emergency construction, was examined. Reinforced concrete specimens were constructed to experimental study. The seismic performence of specimes retrifitted with FRP seismic reinforcement were evaluated. As a result, the seismic performance of specimen reinforced with FRP seismic reinforcement has been improved.

Carbon fiber sheets coated with thin-films of SiO2 and γ-Al2O3 as electrodes in capacitive deionization: Relationship between properties of the oxide films and electrode performance

Nanoporous thin-film coatings of SiO2 and γ-Al2O3 on low surface area carbon fiber sheets may provide an alternative electrode material for capacitive deionization (CDI). In this paper, composite electrodes were fabricated by dipping a low surface area carbon fiber support (less than 2m2/g) into metal oxide sols of either acidic SiO2 (pH 2.9), basic SiO2 (pH 8.3) or γ-AlOOH. Furthermore, the number of times the supports were dipped into the respective sols was varied in an effort to deposit different quantities of the metal oxide. This resulted in composite electrodes with metal oxide contents ranging from 1.5 to 6.7% by weight and specific surface areas from 6 to 35m2/g. When these electrodes were submitted to CDI testing, the rate, as well as the quantity of Ca2+ removed, exceeded that of the uncoated carbon support, independent of the metal oxide coating utilized. Moreover, after 30min of removal, all of the composite electrodes removed >90% of the Ca2+ from a 1.0mM CaCl2 solution – an increase of over 30% as compared to that of the uncoated carbon. In addition, the rate of Ca2+ removal appeared to be dependent upon the nature of the metal oxide coating (SiO2>γ-Al2O3) on the carbon support. The ion removal observed in this work may be driven by electrical double layer formation, specific adsorption, and/or faradaic reactions, such as the oxidation of Cl− to ClO3−. During the regeneration of the electrode, it was shown that the application of an optimal electric potential increased the quantity of Ca2+ desorbed after 30min by approximately 60% for an uncoated pair of electrodes and 90% for a coated pair as compared with electrode regeneration performed under no applied potential. Furthermore, the coated electrode pair was able to withstand a higher voltage for regeneration than an uncoated pair before adsorption of counter-ions exceeded that of co-ions desorption.

Modified Damage Assessment and Repair Design for Underpass Bridge Based on Fire Effect

Due to the fire effect, a frame underpass bridge had suffered a huge damage in Changjiang road in Harbin in the direction to Acheng. One span of the bridge was burned in large area, parts of which were burned badly. Many adjacent beams turned black at bottom of roofs; parts decoration of side wall were damaged to some extent. As a result, both directions of the traffic were disrupted, causing traffic jams. To make sure of repairing and restoring the traffic during the shortest period, Harbin municipal committee established the Changjiang road rescue headquarters. Under the precondition of utmost to save money and ensure that the repaired underpasses technology standards meet the design requirements, the research group were about to use steel plate or carbon fiber sheet as the reinforcing material, after detecting and identifying the bridge damage. Through a comprehensive consideration for the ascension of normal section bearing capacity of two reinforcing materials, pasting carbon fiber sheet was adopted to complete repair reinforcement scheme.

Reliability-Based Balanced Condition for Strengthened RC Beams

Based on the experimental result of the flexure capability of reinforced concrete beams strengthened by carbon fiber sheets, the stress distribution changes only after steel yielding and carbon fiber sheets function better. However serious the extent of the damage is before strengthened, the tensile strain of main steel reaches about 1.6 times of the yield strain for the secondary grade of steel as failure happens. To satisfy the object reliability indicator, reliability is analyzed using the ratio of the steel strain at the balanced failure to the yield strain as variable to obtain its optimum value, which is coincide with the experimental result, and makes better consistency between calculated reliability indicator and object reliability indicator.

Ultra-High-Strength Concrete-Filled FRP Tubes: Compression Tests on Square and Rectangular Columns

This paper presents the partial results of an experimental program undertaken to investigate the behavior of square and rectangular ultra-high-strength concrete (UHSC)-filled fiber reinforced polymer (FRP) tubes (UHSCFFTs) under axial compression. The effects of the amount of confinement, cross-sectional aspect ratio and corner radius were investigated experimentally through the tests of 24 concrete-filled FRP tubes (CFFTs) that were manufactured using unidirectional carbon fiber sheets and UHSC with 108 MPa average compressive strength. Test results indicate that sufficiently confined square and rectangular UHSCFFTs can exhibit highly ductile behavior. The results also indicate that HSCFFTs having tubes of low confinement effectiveness may experience a significant strength loss at the point of transition on their stress-strain curves. Examination of the test results have led to a number of important observations on the influence of corner radius and sectional aspect ratio, which are presented and discussed in the paper.