WorldWideScience

Sample records for cfrp program

  1. Strengthening of defected beam–column joints using CFRP

    Directory of Open Access Journals (Sweden)

    Mohamed H. Mahmoud

    2014-01-01

    Full Text Available This paper presents an experimental study for the structural performance of reinforced concrete (RC exterior beam–column joints rehabilitated using carbon-fiber-reinforced polymer (CFRP. The present experimental program consists of testing 10 half-scale specimens divided into three groups covering three possible defects in addition to an adequately detailed control specimen. The considered defects include the absence of the transverse reinforcement within the joint core, insufficient bond length for the beam main reinforcement and inadequate spliced implanted column on the joint. Three different strengthening schemes were used to rehabilitate the defected beam–column joints including externally bonded CFRP strips and sheets in addition to near surface mounted (NSM CFRP strips. The failure criteria including ultimate capacity, mode of failure, initial stiffness, ductility and the developed ultimate strain in the reinforcing steel and CFRP were considered and compared for each group for the control and the CFRP-strengthened specimens. The test results showed that the proposed CFRP strengthening configurations represented the best choice for strengthening the first two defects from the viewpoint of the studied failure criteria. On the other hand, the results of the third group showed that strengthening the joint using NSM strip technique enabled the specimen to outperform the structural performance of the control specimen while strengthening the joints using externally bonded CFRP strips and sheets failed to restore the strengthened joints capacity.

  2. Strengthening of defected beam-column joints using CFRP.

    Science.gov (United States)

    Mahmoud, Mohamed H; Afefy, Hamdy M; Kassem, Nesreen M; Fawzy, Tarek M

    2014-01-01

    This paper presents an experimental study for the structural performance of reinforced concrete (RC) exterior beam-column joints rehabilitated using carbon-fiber-reinforced polymer (CFRP). The present experimental program consists of testing 10 half-scale specimens divided into three groups covering three possible defects in addition to an adequately detailed control specimen. The considered defects include the absence of the transverse reinforcement within the joint core, insufficient bond length for the beam main reinforcement and inadequate spliced implanted column on the joint. Three different strengthening schemes were used to rehabilitate the defected beam-column joints including externally bonded CFRP strips and sheets in addition to near surface mounted (NSM) CFRP strips. The failure criteria including ultimate capacity, mode of failure, initial stiffness, ductility and the developed ultimate strain in the reinforcing steel and CFRP were considered and compared for each group for the control and the CFRP-strengthened specimens. The test results showed that the proposed CFRP strengthening configurations represented the best choice for strengthening the first two defects from the viewpoint of the studied failure criteria. On the other hand, the results of the third group showed that strengthening the joint using NSM strip technique enabled the specimen to outperform the structural performance of the control specimen while strengthening the joints using externally bonded CFRP strips and sheets failed to restore the strengthened joints capacity. PMID:25685473

  3. Strengthening of defected beam–column joints using CFRP

    Science.gov (United States)

    Mahmoud, Mohamed H.; Afefy, Hamdy M.; Kassem, Nesreen M.; Fawzy, Tarek M.

    2013-01-01

    This paper presents an experimental study for the structural performance of reinforced concrete (RC) exterior beam–column joints rehabilitated using carbon-fiber-reinforced polymer (CFRP). The present experimental program consists of testing 10 half-scale specimens divided into three groups covering three possible defects in addition to an adequately detailed control specimen. The considered defects include the absence of the transverse reinforcement within the joint core, insufficient bond length for the beam main reinforcement and inadequate spliced implanted column on the joint. Three different strengthening schemes were used to rehabilitate the defected beam–column joints including externally bonded CFRP strips and sheets in addition to near surface mounted (NSM) CFRP strips. The failure criteria including ultimate capacity, mode of failure, initial stiffness, ductility and the developed ultimate strain in the reinforcing steel and CFRP were considered and compared for each group for the control and the CFRP-strengthened specimens. The test results showed that the proposed CFRP strengthening configurations represented the best choice for strengthening the first two defects from the viewpoint of the studied failure criteria. On the other hand, the results of the third group showed that strengthening the joint using NSM strip technique enabled the specimen to outperform the structural performance of the control specimen while strengthening the joints using externally bonded CFRP strips and sheets failed to restore the strengthened joints capacity. PMID:25685473

  4. Behaviour of RC beams shear strengthening with NSM CFRP laminates

    OpenAIRE

    Dias, Salvador J. E.; Barros, Joaquim A. O.

    2008-01-01

    The effectiveness of the Near Surface Mounted (NSM) technique with Carbon Fiber Reinforced Polymer (CFRP) laminates for the shear strengthening of T cross section reinforced concrete (RC) beams is assessed by experimental research. The influence of the percentage and inclination of CFRP laminates on the shear strengthening contribution was evaluated. The experimental program also includes beams strengthened according to the externally bonded reinforcement (EBR) technique in ord...

  5. Effects of CFRP Strengthening on Dynamic and Fatigue Responses of Composite Bridge

    OpenAIRE

    2014-01-01

    This paper investigates the effect of CFRP strengthening on dynamic and fatigue responses of composite bridge using finite element program ABAQUS. Dynamic and fatigue responses of composite bridge due to truck load based on AASHTO standard are investigated. Two types of CFRP strengthening techniques, CFRP sheets and CFRP deck, are applied to both the damaged and undamaged bridges. For the case of damaged bridge, two through-thickness crack sizes, 3 mm and 6 mm in depth, are assumed at midspan...

  6. Thermomechanical responses of concrete members strengthened with cfrp sheets

    Science.gov (United States)

    Alqurashi, Abdulaziz

    Strengthening structural members means to be able to carry additional loads. Since, 1990s, a lot of materials and techniques have been established to not only increasing the capacity of member but also facing deterioration. Deterioration has become one of the worst highly maintenance cost. According to The ASCE, 27.1% of all bridges in the United States are not effectual. This is because the high traffic reflects negatively to structural members and cause deterioration of these members. This problem has been cost a lot of money. In addition, FRP has approved that it can increase the capacity of member and overcome some disadvantages such as deterioration. Therefore, CFRP sheet has become widely used. However, high temperatures affect the performance of externally bonded CFRP sheet negatively. Investigation should be carried out on relaxation and flexural performance of members under different temperatures. Therefore, this thesis focus on analyzing and investigating the performance of strengthened members exposed to elevated temperatures (25 to 175 °C). The experimental program was divided to two main parts. First, 144 strengthen concrete blocks 100mm X 150mm X 75mm has been exposed to elevated temperatures. These blocks have two main categories, which are different CFRP sheet width, and different CFRP sheet length. Different CFRP width has three types, which are type 0.25B (25mm x 100mm), type 0.5B (50mm x 100mm) and type 0.75B (75mm x 100mm). Also, Different CFRP length has three types, which are type L e (bonded area of 50 mm by 90mm), 1.25 Le (area of 50mm by 125mm) and type 1.5Le (50mm by 137 mm). Second, studying the performance of RC beams exposed to elevated temperatures.

  7. Effects of CFRP Strengthening on Dynamic and Fatigue Responses of Composite Bridge

    Directory of Open Access Journals (Sweden)

    Kittisak Kuntiyawichai

    2014-01-01

    Full Text Available This paper investigates the effect of CFRP strengthening on dynamic and fatigue responses of composite bridge using finite element program ABAQUS. Dynamic and fatigue responses of composite bridge due to truck load based on AASHTO standard are investigated. Two types of CFRP strengthening techniques, CFRP sheets and CFRP deck, are applied to both the damaged and undamaged bridges. For the case of damaged bridge, two through-thickness crack sizes, 3 mm and 6 mm in depth, are assumed at midspan of the steel girders. Furthermore, effects of the number of steel girders on the dynamic and fatigue responses are also considered. The results show that the maximum responses of composite bridges occur for dual lane cases. By using CFRP as a strengthening material, the maximum stress and deflection of the steel girders reduce and consequently increase the fatigue life of the girders. After introducing initial crack into the steel girders of the composite bridges, the fatigue life of the bridges is dramatically reduced. However, the overall performance of the damaged composite bridge can be improved by using CFRP, albeit with less effectiveness. Therefore, if cracks are found, steel welding must be performed before strengthening the composite bridge by CFRP.

  8. Bond Strength of Composite CFRP Reinforcing Bars in Timber

    Directory of Open Access Journals (Sweden)

    Marco Corradi

    2015-07-01

    Full Text Available The use of near-surface mounted (NSM fibre-reinforced polymer (FRP bars is an interesting method for increasing the shear and flexural strength of existing timber members. This article examines the behaviour of carbon FRP (CFRP bars in timber under direct pull-out conditions. The objective of this experimental program is to investigate the bond strength between composite bars and timber: bars were epoxied into small notches made into chestnut and fir wood members using a commercially-available epoxy system. Bonded lengths varied from 150 to 300 mm. Failure modes, stress and strain distributions and the bond strength of CFRP bars have been evaluated and discussed. The pull-out capacity in NSM CFRP bars at the onset of debonding increased with bonded length up to a length of 250 mm. While CFRP bar’s pull-out was achieved only for specimens with bonded lengths of 150 and 200 mm, bar tensile failure was mainly recorded for bonded lengths of 250 and 300 mm.

  9. Nonlinear finite element analysis of mechanical characteristics on CFRP composite pressure vessels

    International Nuclear Information System (INIS)

    CFRP(Carbon Fibre Reinforced Plastic) composite pressure vessel was calculated using finite element program of ANSYS for their mechanical characteristics in this paper. The elastic-plastic model and elements of Solid95 were selected for aluminium alloys of gas cylinder. Also liner-elastic model and layer elements of Shell99 were adopted for carbon fibre/epoxy resin. The stress state of CFRP composite pressure vessel was calculated under different internal pressures include pre-stressing pressures, working pressures, test hydraulic pressures, minimum destructive pressures etcetera to determine the size of gas cylinder and layer parameter of carbon fibre. The mechanical characteristics CFRP composite vessel could were using to design and test of gas cylinder. Numerical results showed that finite element model and calculating method were efficient for study of CFRP gas cylinder and useful for engineering design.

  10. Inter-laminar shear stress in hybrid CFRP/austenitic steel

    Directory of Open Access Journals (Sweden)

    J. Lopes

    2015-01-01

    Full Text Available Bolted joints are the most common solution for joining composite components in aerospace structures. Critical structures such as wing to fuselage joints, or flight control surface fittings use bolted joining techniques. Recent research concluded that higher bearing strengths in composite bolted joints can be achieved by a CFRP/ Titanium hybrid lay-up in the vicinity of the bolted joint. The high costs of titanium motivate a similar research with the more cost competitive austenitic steel. An experimental program was performed in order to compare the apparent inter-laminar shear stress (ILSS of a CFRP reference beam with the ILSS of hybrid CFRP/Steel beams utilizing different surface treatments in the metallic ply. The apparent ILSS was determined by short beam test, a three-point bending test. Finite element models using cohesive elements in the CFRP/Steel interface were built to simulate the short beam test in the reference beam and in the highest interlaminar shear stress hybrid beam. The main parameters for a FEM simulation of inter laminar shear are the cohesive elements damage model and appropriate value for the critical energy release rate. The results show that hybrid CFRP/Steel have a maximum ILSS very similar to the ILSS of the reference beam. Hybrid CFRP/Steel is a competitive solution when compared with the reference beam ILSS. FEM models were able to predict the maximum ILSS in each type of beam.

  11. The Influence of CFRP Anchorage on Achieving Sectional Flexural Capacity of Strengthened Concrete Beams

    Directory of Open Access Journals (Sweden)

    Hayder A. Rasheed

    2015-12-01

    Full Text Available This research program is intended to verify the influence of using distributed external U-wrap CFRP anchorage to shift the failure mode from overall debonding to sectional flexural failure for concrete beams externally bonded with CFRP sheets. Premature cover delamination and FRP debonding are predominant failure modes in FRP flexural strengthening that may be delayed or prevented by using FRP anchorage. The present experimental study aims to comparatively prove that proper anchorage of flexural strengthening is anticipated to yield a classical flexural failure by FRP rupture or concrete crushing. Once the cohesion of concrete and/or the adhesion with the FRP is exhausted, the U-wraps are engaged to provide anchorage to the flexural FRP through shear friction. Accordingly, three identical T beams and three identical rectangular beams were designed and constructed to examine the capacity improvement by preventing premature debonding failure. The first specimen in each series was tested as a control beam. The second specimen in each series was strengthened using five layers of flexural CFRP in order to admit a debonding failure. The third specimen in each series was strengthened with the same five layers of flexural CFRP plus additional transverse CFRP U-wraps. This study proved that it is possible to quantify the higher flexural capacity of CFRP strengthened beams using external anchorage.

  12. Effect of CFRP Plate Location on Flexural Behavior of RC Beam Strengthened with CFRP Plate

    Directory of Open Access Journals (Sweden)

    Mohammed Jassam Mohammed Altaee

    2011-01-01

    Full Text Available Location of CFRP plate, as a mode of failure, is one of the major limitations when using externally bonded carbon fiber reinforced polymer (CFRP plates in strengthening of RC beams. In this work, mode of CFRP plate location was analytically investigated. A non-linear finite element model is proposed in order to analyze experimental data presented by David et.al.[1]. The eight node brick element (SOLID65 as denoted in ANSYS is used to model reinforced concrete and four node shell element (SHELL41 is used to represented CFRP plate, bond between concrete and CFRP plate represented by interface element (CONTAC52. The results obtained from analytical study explained that the best location of CFRP is at lower edges of concrete beam.

  13. Concrete retrofitting using CFRP and geopolymer mortars

    OpenAIRE

    E. Vasconcelos; S. Fernandes; Aguiar, J. L. Barroso de; Torgal, Fernando Pacheco

    2011-01-01

    A new development in the repair and strengthening of reinforced concrete systems is the use of carbon fiber reinforced polymers (CFRP) strips bonded to concrete substrate with epoxy resins. It has been reported that epoxy adhesive are extremely sensitive to high temperatures. Some authors conclude that the epoxy temperature should not exceed 70 ºC in order to safeguard the adhesiveness of the epoxy and, thus, the integrity and adequate functioning of CFRP. It is noted that even frequently ...

  14. Treatment of CFRP by IAR method and its effect on the fracture behavior of adhesive bonded CFRP/aluminum composites

    International Nuclear Information System (INIS)

    It was shown in the previous studies that adhesive shear strength of carbon fiber reinforced plastics (CFRP) to aluminum composites could be improved by the surface treatment of CFRP using Ar+ ion irradiation. In the present work, the effect of CFRP treatment by Ar+ ion irradiation on the fracture behavior of CFRP/aluminum joint was studied. The aluminum used was 7075-T6 and the CFRP used was multi-directional graphite/epoxy composites whose stacking sequence was [0 deg. /±45 deg. /0 deg. ]3s. The surface of CFRP was treated using Ar+ ion irradiation in an oxygen environment. The Ar+ ion dose used was 1x1016 ions cm-2. Fracture toughness of CFRP/aluminum joint was determined from cracked lap shear specimens using work factor approach. Then, the fracture toughness of ion beam-treated CFRP/aluminum joint was compared with that of untreated CFRP/aluminum joint. The results showed that the fracture toughness of ion beam-treated CFRP/aluminum case was about 72% higher than that of untreated CFRP/aluminum case. X-ray photoelectron spectrometer analysis showed that intensity of hydrophilic bonds, C-O (carbonyl group) and O-C-O (carboxyl group) was increased by the Ar+ ion-irradiation in an oxygen environment. Scanning electron microscope examination showed that cohesive failure occurred for ion beam-treated CFRP/aluminum joint while adhesive failure occurred for untreated CFRP/aluminum joint

  15. CFRP Mechanical Anchorage for Externally Strengthened RC Beams under Flexure

    Science.gov (United States)

    Ali, Alnadher; Abdalla, Jamal; Hawileh, Rami; Galal, Khaled

    De-bonding of carbon fiber reinforced polymers (CFRP) sheets and plates from the concrete substrate is one of the major reasons behind premature failures of beams that are externally strengthened with such CFRP materials. To delay or prevent de-bonding and therefore enhancing the load carrying capacity of strengthened beams, several anchorage systems were developed and used. This paper investigates the use of CFRP mechanical anchorage of CFRP sheets and plates used to externally strengthen reinforced concrete beams under flexure. The pin-and-fan shape CFRP anchor, which is custom-made from typical rolled fiber sheets and bundles of loose fiber is used. Several reinforced concrete beams were casted and tested in standard four-point bending scheme to study the effectiveness of this anchorage system. The beams were externally strengthened in flexure with bonded CFRP sheets and plates and then fastened to the soffit of the beams' using various patterns of CFRP anchors. It is observed that the CFRP plates begins to separate from the beams as soon as de-bonding occurs in specimens without CFRP anchors, while in beams with CFRP anchors de-bonding was delayed leading to increase in the load carrying capacity over the un-anchored strengthened beams.

  16. Behavior of preloaded RC beams strengthened with CFRP laminates

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Eighteen reinforced concrete beams, including 16 beams strengthened with CFRP laminate at different levels of preload and 2 control beams, were tested to investigate the influence ofpreload level on flexural behavior of CFRP-strengthened RC beam. The experimental parameters include rebar ratios, number of plies of CFRP laminates and preload level at the time of strengthening. Theoretical analysis was also carried out to explain the experimental phenomena and results. The experimental and theoretical results indicated that the preload level has more influence on the stiffness and deflection of the strengthened beam, bothat post-cracking and post-yielding stage, than that on the yielding and ultimate flexural strength of the strengthened beam. The main failure mode of CFRP-strengthened beam is the intermediate crack-induced debonding of CFRP laminates, provided that the development length of CFRP laminates and shear capacity of the beam are sufficient.

  17. Protection of RC elements strengthened with CFRP against high temperatures

    OpenAIRE

    Aguiar, J. L. Barroso de; Gorski, M.; Camões, Aires; Vaz, Nelson; Majewski, S.

    2007-01-01

    The strengthening of RC elements with CFRP is a technique that has been acquiring more and more potential. The bond between the CFRP laminates and the concrete support is usually made with epoxy adhesives. However, it is in this part that the integrity of the system can be affected, namely by exposure to high temperatures. In order to evaluate the thermal behaviour, reference RC and CFRP strengthened RC specimens were tested. After cyclical thermal expositions, with temperatures rising betwee...

  18. Study of the Tensile Properties of CFRP Strengthened Steel Plates

    OpenAIRE

    Yiyan Lu; Weijie Li; Shan Li; Xiaojin Li; Tao Zhu

    2015-01-01

    This paper presents the experimental results of steel plates strengthened with carbon fiber reinforced polymer (CFRP) sheets under tensile load. The number of CFRP layers (ranging from one to four), strengthening schemes (single-sided and double-sided bonding), and temperatures (ranging from 25 to 120 °C) were investigated. Results showed that the number of CFRP layers and strengthening schemes had insignificant effects on failure modes of specimens. The failure modes were dominated by the de...

  19. Strengthening of a railway bridge with NSMR and CFRP tubes

    DEFF Research Database (Denmark)

    Täljsten, Björn; Bennitz, Anders; Danielsson, Georg

    2008-01-01

    Strengthening of structures with CFRP is today considered an accepted method to upgrade concrete structures. In this paper two different CFRP strengthening systems are combined to give extended service life to a Swedish double-trough-double-track railway bridge, constructed in concrete with a 10 ....... Sensors on bars and tubes display proofs of utilization of the CFRP while displacement sensors and strain gauges on the steel reinforcement due to the small loads in the service limit state show minor effect....

  20. Analytical and Experimental Study of Residual Stresses in CFRP

    Directory of Open Access Journals (Sweden)

    Chia-Chin Chiang

    2013-01-01

    Full Text Available Fiber Bragg Grating sensors (FBGs have been utilized in various engineering and photoelectric fields because of their good environment tolerance. In this research, residual stresses of carbon fiber reinforced polymer composites (CFRP were studied using both experimental and analytical approach. The FBGs were embedded inside middle layers of CFRP to study the formation of residual stress during curing process. Finite element analysis was performed using ABAQUS software to simulate the CFRP curing process. Both experimental and simulation results showed that the residual stress appeared during cooling process and the residual stresses could be released when the CFRP was machined to a different shape.

  1. Strengthening of old metallic structures in fatigue with CFRP materials

    DEFF Research Database (Denmark)

    Hansen, Christian Skodborg; Schmidt, Jacob Wittrup; Täljsten, Björn

    2007-01-01

    manufactured and tested in fatigue with constant amplitude. The test series focuses on different CFRP configurations with and without prestressing and it has been shown possible to slow down crack growth in the steel substrate. The test specimens with prestressed CFRP laminates showed the ability to stop crack...

  2. NONLINEAR ANALYSIS OF CFRP- PRESTRESSED CONCRETE BEAMS SUBJECTED TO INCREMENTAL STATIC LOADING BY FINITE ELEMENTS

    OpenAIRE

    Husain M. Husain; Nazar K. Oukaili

    2013-01-01

    In this work a program is developed to carry out the nonlinear analysis (material nonlinearity) of prestressed concrete beams using tendons of carbon fiber reinforced polymer (CFRP) instead of steel. The properties of this material include high strength, light weight, and insusceptibility to corrosion and magnetism. This material is still under investigation, therefore it needs continuous work to make it beneficial in concrete design. Four beams which are tested experimentally by Yan et al. a...

  3. Shear capacity of reinforced concrete columns strengthened with CFRP sheet

    Institute of Scientific and Technical Information of China (English)

    XIE Jian; LIU Xue-mei; ZHAO Tong

    2005-01-01

    This paper discusses the results of tests on the shear capacity of reinforced concrete columns strengthened with carbon fiber reinforced plastic (CFRP) sheet. The shear transfer mechanism of the specimens reinforced with CFRP sheet was studied. The factors affecting the shear capacity of reinforced concrete columns strengthened with CFRP sheet were analyzed. Several suggestions such as the number of layers, width and tensile strength of the CFRP sheet are proposed for this new strengthening technique. Finally, a simple and practical design method is presented in the paper. The calculated results of the suggested method are shown to be in good agreement with the test results. The suggested design method can be used in evaluating the shear capacity of reinforced concrete columns strengthened with CFRP sheet.

  4. Crack growth monitoring at CFRP bond lines

    Science.gov (United States)

    Rahammer, M.; Adebahr, W.; Sachse, R.; Gröninger, S.; Kreutzbruck, M.

    2016-02-01

    With the growing need for lightweight technologies in aerospace and automotive industries, fibre-reinforced plastics, especially carbon-fibre (CFRP), are used with a continuously increasing annual growth rate. A promising joining technique for composites is adhesive bonding. While rivet holes destroy the fibres and cause stress concentration, adhesive bond lines distribute the load evenly. Today bonding is only used in secondary structures due to a lack of knowledge with regard to long-term predictability. In all industries, numerical simulation plays a critical part in the development process of new materials and structures, while it plays a vital role when it comes to CFRP adhesive bondings conducing the predictability of life time and damage tolerance. The critical issue with adhesive bondings is crack growth. In a dynamic tensile stress testing machine we dynamically load bonded CFRP coupon specimen and measure the growth rate of an artificially started crack in order to feed the models with the results. We also investigate the effect of mechanical crack stopping features. For observation of the bond line, we apply two non-contact NDT techniques: Air-coupled ultrasound in slanted transmission mode and active lockin-thermography evaluated at load frequencies. Both methods give promising results for detecting the current crack front location. While the ultrasonic technique provides a slightly higher accuracy, thermography has the advantage of true online monitoring, because the measurements are made while the cyclic load is being applied. The NDT methods are compared to visual inspection of the crack front at the specimen flanks and show high congruence. Furthermore, the effect of crack stopping features within the specimen on the crack growth is investigated. The results show, that not all crack fronts are perfectly horizontal, but all of them eventually come to a halt in the crack stopping feature vicinity.

  5. NDE and SHM Simulation for CFRP Composites

    Science.gov (United States)

    Leckey, Cara A. C.; Parker, F. Raymond

    2014-01-01

    Ultrasound-based nondestructive evaluation (NDE) is a common technique for damage detection in composite materials. There is a need for advanced NDE that goes beyond damage detection to damage quantification and characterization in order to enable data driven prognostics. The damage types that exist in carbon fiber-reinforced polymer (CFRP) composites include microcracking and delaminations, and can be initiated and grown via impact forces (due to ground vehicles, tool drops, bird strikes, etc), fatigue, and extreme environmental changes. X-ray microfocus computed tomography data, among other methods, have shown that these damage types often result in voids/discontinuities of a complex volumetric shape. The specific damage geometry and location within ply layers affect damage growth. Realistic threedimensional NDE and structural health monitoring (SHM) simulations can aid in the development and optimization of damage quantification and characterization techniques. This paper is an overview of ongoing work towards realistic NDE and SHM simulation tools for composites, and also discusses NASA's need for such simulation tools in aeronautics and spaceflight. The paper describes the development and implementation of a custom ultrasound simulation tool that is used to model ultrasonic wave interaction with realistic 3-dimensional damage in CFRP composites. The custom code uses elastodynamic finite integration technique and is parallelized to run efficiently on computing cluster or multicore machines.

  6. Adhesion between high-strength concrete, epoxy resin and CFRP

    OpenAIRE

    Aguiar, J. L. Barroso de; Krzywon, Rafal; Camões, Aires; Gorski, M.; Dawczynski, Szymon

    2008-01-01

    This paper presents a study on the adhesion between high-strength concrete, epoxy resin and CFRP. The adhesion of the high-strength concrete was compared with the same property measured in conventional concrete. Shear tests were made to test adhesion from concretes to epoxy resin. Flexural tests were used to evaluate the adhesion between concretes, epoxy and CFRP. The effect of temperature was also evaluated. For ordinary temperatures (20 ºC) the results showed a better flexural performance o...

  7. Damage Detection in CFRP Plates Using Spectral Entropy

    Directory of Open Access Journals (Sweden)

    E. Castro

    2014-01-01

    Full Text Available Damage detection techniques using vibrations are based on measuring the changes in the vibration parameters of a structure. This paper studies the viability of the spectral entropy as a new damage detection parameter to detect the presence of damage in a composite fiber reinforced polymers (CFRP plate. To carry out this study, the vibrations in a CFRP plate with and without damage were measured and the correlation between damage and spectral entropy has been researched.

  8. Rotary ultrasonic machining of CFRP: A comparison with grinding.

    Science.gov (United States)

    Ning, F D; Cong, W L; Pei, Z J; Treadwell, C

    2016-03-01

    Carbon fiber reinforced plastic (CFRP) composites have been intensively used in various industries due to their superior properties. In aircraft and aerospace industry, a large number of holes are required to be drilled into CFRP components at final stage for aircraft assembling. There are two major types of methods for hole making of CFRP composites in industry, twist drilling and its derived multi-points machining methods, and grinding and its related methods. The first type of methods are commonly used in hole making of CFRP composites. However, in recent years, rotary ultrasonic machining (RUM), a hybrid machining process combining ultrasonic machining and grinding, has also been successfully used in drilling of CFRP composites. It has been shown that RUM is superior to twist drilling in many aspects. However, there are no reported investigations on comparisons between RUM and grinding in drilling of CFRP. In this paper, these two drilling methods are compared in five aspects, including cutting force, torque, surface roughness, hole diameter, and material removal rate. PMID:26614168

  9. Strengthening Reinforced Concrete Beams with CFRP and GFRP

    Directory of Open Access Journals (Sweden)

    Mehmet Mustafa Önal

    2014-01-01

    Full Text Available Concrete beams were strengthened by wrapping the shear edges of the beams twice at 45° in opposite directions by either carbon fiber reinforced polymer (CFRP or glass fiber reinforced polymer (GFRP. The study included 3 CFRP wrapped beams, 3 GFRP wrapped beams, and 3 control beams, all of which were 150 × 250 × 2200 mm and manufactured with C20 concrete and S420a structural steel at the Gazi University Technical Education Faculty labs, Turkey. Samples in molds were cured by watering in the open air for 21 days. Four-point bending tests were made on the beam test specimens and the data were collected. Data were evaluated in terms of load displacement, bearing strength, ductility, and energy consumption. In the CFRP and GFRP reinforced beams, compared to controls, 38% and 42%, respectively, strength increase was observed. In all beams, failure-flexural stress occurred in the center as expected. Most cracking was observed in the flexural region 4. A comparison of CFRP and GFRP materials reveals that GFRP enforced parts absorb more energy. Both materials yielded successful results. Thicker epoxy application in both CFRP and GFRP beams was considered to be effective in preventing break-ups.

  10. Strut Deformation in CFRP-Strengthened Reinforced Concrete Deep Beams

    Directory of Open Access Journals (Sweden)

    Mohammad Panjehpour

    2014-01-01

    Full Text Available Strut-and-tie model (STM method evolved as one of the most useful designs for shear critical structures and discontinuity regions (D-regions. It provides widespread applications in the design of deep beams as recommended by many codes. The estimation of bottle-shaped strut dimensions, as a main constituent of STM, is essential in design calculations. The application of carbon fibre reinforced polymer (CFRP as lightweight material with high tensile strength for strengthening D-regions is currently on the increase. However, the CFRP-strengthening of deep beam complicates the dimensions estimation of bottle-shaped strut. Therefore, this research aimed to investigate the effect of CFRP-strengthening on the deformation of RC strut in the design of deep beams. Two groups of specimens comprising six unstrengthened and six CFRP-strengthened RC deep beams with the shear span to the effective depth ratios (a/d of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were constructed in this research. These beams were tested under four-point bending configuration. The deformation of struts was experimentally evaluated using the values of strain along and perpendicular to the strut centreline. The evaluation was made by the comparisons between unstrengthened and CFRP-strengthened struts regarding the widening and shortening. The key variables were a/d ratio and applied load level.

  11. Strut deformation in CFRP-strengthened reinforced concrete deep beams.

    Science.gov (United States)

    Panjehpour, Mohammad; Chai, Hwa Kian; Voo, Yen Lei

    2014-01-01

    Strut-and-tie model (STM) method evolved as one of the most useful designs for shear critical structures and discontinuity regions (D-regions). It provides widespread applications in the design of deep beams as recommended by many codes. The estimation of bottle-shaped strut dimensions, as a main constituent of STM, is essential in design calculations. The application of carbon fibre reinforced polymer (CFRP) as lightweight material with high tensile strength for strengthening D-regions is currently on the increase. However, the CFRP-strengthening of deep beam complicates the dimensions estimation of bottle-shaped strut. Therefore, this research aimed to investigate the effect of CFRP-strengthening on the deformation of RC strut in the design of deep beams. Two groups of specimens comprising six unstrengthened and six CFRP-strengthened RC deep beams with the shear span to the effective depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were constructed in this research. These beams were tested under four-point bending configuration. The deformation of struts was experimentally evaluated using the values of strain along and perpendicular to the strut centreline. The evaluation was made by the comparisons between unstrengthened and CFRP-strengthened struts regarding the widening and shortening. The key variables were a/d ratio and applied load level. PMID:25197698

  12. TEA CO2 laser machining of CFRP composite

    Science.gov (United States)

    Salama, A.; Li, L.; Mativenga, P.; Whitehead, D.

    2016-05-01

    Carbon fibre-reinforced polymer (CFRP) composites have found wide applications in the aerospace, marine, sports and automotive industries owing to their lightweight and acceptable mechanical properties compared to the commonly used metallic materials. Machining of CFRP composites using lasers can be challenging due to inhomogeneity in the material properties and structures, which can lead to thermal damages during laser processing. In the previous studies, Nd:YAG, diode-pumped solid-state, CO2 (continuous wave), disc and fibre lasers were used in cutting CFRP composites and the control of damages such as the size of heat-affected zones (HAZs) remains a challenge. In this paper, a short-pulsed (8 μs) transversely excited atmospheric pressure CO2 laser was used, for the first time, to machine CFRP composites. The laser has high peak powers (up to 250 kW) and excellent absorption by both the carbon fibre and the epoxy binder. Design of experiment and statistical modelling, based on response surface methodology, was used to understand the interactions between the process parameters such as laser fluence, repetition rate and cutting speed and their effects on the cut quality characteristics including size of HAZ, machining depth and material removal rate (MRR). Based on this study, process parameter optimization was carried out to minimize the HAZ and maximize the MRR. A discussion is given on the potential applications and comparisons to other lasers in machining CFRP.

  13. Damage in woven CFRP laminates under impact loading

    Directory of Open Access Journals (Sweden)

    Silberschmidt V.V.

    2012-08-01

    Full Text Available Carbon fibre-reinforced polymer (CFRP composites used in sports products can be exposed to different in-service conditions such as large dynamic bending deformations caused by impact loading. Composite materials subjected to such loads demonstrate various damage modes such as matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution affects both in-service properties and performance of CFRP that can deteriorate with time. These failure modes need adequate means of analysis and investigation, the major approaches being experimental characterisation and numerical simulations. This research deals with a deformation behaviour and damage in composite laminates due to dynamic bending. Experimental tests are carried out to characterise the behaviour of a woven CFRP material under large-deflection dynamic bending in impact tests carried out to obtain the force-time and absorbed energy profiles for CFRP laminates. Damage in the impacted laminates is analysed using optical microscopy. Numerical simulations are performed to study the deformation behaviour and damage in CFRP for cases of large-deflection bending based on three-dimensional finite-element models implemented in the commercial code Abaqus/Explicit. Multiple layers of bilinear cohesive-zone elements are employed to model the initiation and progression of inter-ply delamination observed in the microscopy studies. The obtained results of simulations show good agreement with experimental data.

  14. Damage in woven CFRP laminates under impact loading

    Science.gov (United States)

    Ullah, H.; Harland, A. R.; Silberschmidt, V. V.

    2012-08-01

    Carbon fibre-reinforced polymer (CFRP) composites used in sports products can be exposed to different in-service conditions such as large dynamic bending deformations caused by impact loading. Composite materials subjected to such loads demonstrate various damage modes such as matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution affects both in-service properties and performance of CFRP that can deteriorate with time. These failure modes need adequate means of analysis and investigation, the major approaches being experimental characterisation and numerical simulations. This research deals with a deformation behaviour and damage in composite laminates due to dynamic bending. Experimental tests are carried out to characterise the behaviour of a woven CFRP material under large-deflection dynamic bending in impact tests carried out to obtain the force-time and absorbed energy profiles for CFRP laminates. Damage in the impacted laminates is analysed using optical microscopy. Numerical simulations are performed to study the deformation behaviour and damage in CFRP for cases of large-deflection bending based on three-dimensional finite-element models implemented in the commercial code Abaqus/Explicit. Multiple layers of bilinear cohesive-zone elements are employed to model the initiation and progression of inter-ply delamination observed in the microscopy studies. The obtained results of simulations show good agreement with experimental data.

  15. Testing Program of Strengthening Two-way RC Slab Using One-way CFRP Sheets%CFRP板单向加固RC双向板试验方案探析

    Institute of Scientific and Technical Information of China (English)

    江雪; 李浩; 王蕾

    2011-01-01

    In recent years, with lightweight, high strength,can resist erosion and fatigue,and many other advantages, carbon fiber and sheet has been widely used in strengthening structural projects. But its disadvantages are increasingly becoming prominent, such as low elastic modulus, inadequate ductility, and the transmission of shear of epoxy resin layer is limited and so on. Pre-stressed carbon fiber reinforced concrete elements can give full play to the high strength properties of carbon fiber, making the structure more likely close to the ultimate tensile strength at failure, especially the performance of prevent the reinforcement elements from bonding failure is outstanding, as well as anti-stripping properties. By having tense pressure into the CFRP sheets ( cloth) first, and then put them attached to the surface of reinforcement with a new anchor measure. As a result, it will not only improve the mechanical properties of the use of phase, but also extend the life of components.%近年来碳纤维布及片材以其轻质、高强、耐腐蚀、抗疲劳等众多优点,被广泛应用于结构加固工程,但其不足之处也逐渐凸显,例如弹性模量低、延性不足;环氧树脂层传递剪力有限等.预应力碳纤维加固能充分发挥碳纤维的高强性能,使结构在破坏时更趋近极限抗拉强度;尤其在防止加固构件发生粘结破坏,以及抗剥离性能等方面表现突出.通过对CFRP板(布)施加张拉力,然后将预先张拉的碳纤维板(包括布材)粘贴在加固部位的表面进行锚固后,不仅改善了构件使用阶段的受力性能,而且延长了构件的使用年限.

  16. STUDY ON DRILLING CHARACTERISTICS AND MECHANICAL PROPERTIES OF CFRP COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Seung-Chul Lee; Seong-Taek Jeong; Jong-Nam Park; Sun-Jin Kim; Gyu-Jae Cho

    2008-01-01

    Stacking plates of CFRP composite materials are increasingly used because of their unique characteristics.However,unlike other materials used in metallurgy they have a disadvan tage of uneven quality and anisotropy when combined with other composites.Hence,specimens of CFRP stacking plates are manufactured by changing orientation angles throughout three quasi isotropic plies (0°/45°/90°/-45°)6s (03°/453°/903°/-453°)2s,and (06°/456°/906°/- 456°)s and In this study 3-point bending tests and transverse bending tests have been carried out in order to find out mechanical characteristics according to orientation angles by stacking in 6 different types along with the change of stacking composition method of a CFRP composite.

  17. Rotary ultrasonic machining of CFRP composites: a study on power consumption.

    Science.gov (United States)

    Cong, W L; Pei, Z J; Deines, T W; Srivastava, Anil; Riley, L; Treadwell, C

    2012-12-01

    Carbon fiber reinforced plastic (CFRP) composites are very difficult to machine. A large number of holes need to be drilled in CFRP for many applications. Therefore, it is important to develop cost-effective drilling processes. CFRP has been drilled by rotary ultrasonic machining (RUM) successfully. The literature has reports about the effects of input variables on output variables (including cutting force, torque, surface roughness, tool wear, and workpiece delamination) in RUM of CFRP. However, there are no reports on power consumption in RUM of CFRP. This paper reports the first study on power consumption in RUM of CFRP. It reports an experimental investigation on effects of input variables (ultrasonic power, tool rotation speed, feedrate, and type of CFRP) on power consumption of each component (including ultrasonic power supply, spindle motor, coolant pump, and air compressor) and the entire RUM system. PMID:22986155

  18. Shear Strengthening of Corbels with Carbon Fibre Reinforced Polymers (CFRP

    Directory of Open Access Journals (Sweden)

    Nawaz, A.

    2010-09-01

    Full Text Available Corbels constitute what are known as “disturbed” regions in concrete structures, where typical shear failure may be anticipated on the grounds of small shear span-to-depth ratios. The concentration of stress induced by the weight of girders on the very small loadbearing areas in corbels often causes cracking in bridges and other structures. Little experimental research can be found in the literature on the shear strengthening of corbels. In the present study, nine such members were tested. Two had no carbon fibre reinforced polymers attached, while CFRP laminates were externally bonded to the other seven, in a number of different spatial arrangements. Ultimate shear strength was found and compared for all specimens. The results showed that CFRP configuration and geometry directly affected corbel shear strength, which was higher in all the CFRPstrengthened corbels than in the controls. The highest strength values were recorded for specimens whose shear-critical area was wrapped in CFRP.

    Las ménsulas constituyen lo que conocemos como regiones de “distorsión” en las estructuras de hormigón, zonas en que pueden preverse roturas por cortante debido a las bajas relaciones luz de cortante-canto presentes en ellas. La concentración de solicitaciones producida por el peso de las vigas sobre superficies de carga muy reducidas en las ménsulas a menudo provoca el agrietamiento de puentes y otras estructuras de obra civil. En la literatura especializada sobre el refuerzo a cortante de las ménsulas existen escasos ejemplos de estudios experimentales. Para la presente investigación se han realizado ensayos con nueve elementos de este tipo. Dos de ellos no incluían polímeros reforzados con fibra de carbono (CFRP, mientras que los siete restantes llevaban láminas externas de CFRP, dispuestas siguiendo distintas configuraciones espaciales. Los resultados indican que la configuración y la disposición geométrica de los CFRP repercuten

  19. Strengthening Reinforced Concrete Beams with CFRP and GFRP

    OpenAIRE

    Mehmet Mustafa Önal

    2014-01-01

    Concrete beams were strengthened by wrapping the shear edges of the beams twice at 45° in opposite directions by either carbon fiber reinforced polymer (CFRP) or glass fiber reinforced polymer (GFRP). The study included 3 CFRP wrapped beams, 3 GFRP wrapped beams, and 3 control beams, all of which were 150 × 250 × 2200 mm and manufactured with C20 concrete and S420a structural steel at the Gazi University Technical Education Faculty labs, Turkey. Samples in molds were cured by watering in the ...

  20. Development of Mechanical Anchor for CFRP Tendons Using Integrated Sleeve

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Bennitz, Anders; Täljsten, Björn; Pedersen, Henning

    2010-01-01

    A durable and very efficient external strengthening system is achieved if steel tendons for post-tensioning applications can be replaced with CFRP (Carbon Fibre Reinforced Polymer) tendons and if reliable anchorage systems are developed,. This paper presents a newly developed and simple-to-use two...

  1. RC T-Beams Externally Prestressed with Unbonded CFRP

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Bennitz, Anders; Nilimaa, Jonny;

    2010-01-01

    An experimental test series with seven beams externally prestressed with unbonded CFRP 7 (Carbon Fibre Reinforced Polymer) tendons has been performed. Presence of deviator, initial 8 tendon depth and prestressing force are varied. Results and behaviors are compared to 9 common beam theory, matchi...

  2. Novel MRE/CFRP sandwich structures for adaptive vibration control

    Science.gov (United States)

    Kozlowska, J.; Boczkowska, A.; Czulak, A.; Przybyszewski, B.; Holeczek, K.; Stanik, R.; Gude, M.

    2016-03-01

    The aim of this work was the development of sandwich structures formed by embedding magnetorheological elastomers (MRE) between constrained layers of carbon fibre-reinforced plastic (CFRP) laminates. The MREs were obtained by mechanical stirring of a reactive mixture of substrates with carbonyl-iron particles, followed by orienting the particles into chains under an external magnetic field. Samples with particle volume fractions of 11.5% and 33% were examined. The CFRP/MRE sandwich structures were obtained by compressing MREs samples between two CFRP laminates composed. The used A.S.SET resin was in powder form and the curing process was carried out during pressing with MRE. The microstructure of the manufactured sandwich beams was inspected using SEM. Moreover, the rheological and damping properties of the examined materials with and without a magnetic field were experimentally investigated. In addition, the free vibration responses of the adaptive three-layered MR beams were studied at different fixed magnetic field levels. The free vibration tests revealed that an applied non-homogeneous magnetic field causes a shift in natural frequency values and a reduction in the vibration amplitudes of the CFRP/MRE adaptive beams. The reduction in vibration amplitude was attributed mainly to the stiffening effect of the MRE core and only a minor contribution was made by the enhanced damping capacity, which was evidenced by the variation in damping ratio values.

  3. Strengthening of RC Beams with Large Openings in Shear by CFRP Laminates: Experiment and 2D Nonlinear Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    S.C. Chin

    2012-05-01

    Full Text Available This study presents the experimental study and numerical analysis of Reinforced Concrete (RC beams with large square openings placed in the shear region, at a distance 0.5d and d away from the support, strengthened by Carbon Fiber Reinforced Polymer (CFRP laminates. This research aims to investigate the strength losses in RC beam due to the presence of large square openings placed at two different locations in shear region. Also, in order to re-gain the beam structural capacity loss due to the openings, strengthening by CFRP laminates around the openings were studied. A total of six RC beams were tested to failure under four point loading including control beams, un-strengthened and strengthened RC beams with large square openings in shear region at a distance 0.5d and d away from the support. The CFRP strengthening configuration considered in this study was a full wrapping system around the square openings. A nonlinear finite element program, ATENA was used to validate the results of the tested beams. Comparisons between the finite element predictions and experimental results in terms of crack patterns and load deflection relationships are presented. The crack pattern results of the finite element model show good agreement with the experimental data. The load midspan deflection curves of the finite element models exhibited a stiffer result compared to the experimental beams. The possible reason may be due to the perfect bond assumption between the concrete and steel reinforcement.

  4. Static and Dynamic Characteristics of a Long-Span Cable-Stayed Bridge with CFRP Cables

    Directory of Open Access Journals (Sweden)

    Xu Xie

    2014-06-01

    Full Text Available In this study, the scope of CFRP cables in cable-stayed bridges is studied by establishing a numerical model of a 1400-m span of the same. The mechanical properties and characteristics of CFRP stay cables and of a cable-stayed bridge with CFRP cables are here subjected to comprehensive analysis. The anomalies in the damping properties of free vibration, nonlinear parametric vibration and wind fluctuating vibration between steel cables and CFRP cables are determined. The structural stiffness, wind resistance and traffic vibration of the cable-stayed bridge with CFRP cables are also analyzed. It was found that the static performances of a cable-stayed bridge with CFRP cables and steel cables are basically the same. The natural frequencies of CFRP cables do not coincide with the major natural frequencies of the cable-stayed bridge, so the likelihood of CFRP cable-bridge coupling vibration is minuscule. For CFRP cables, the response amplitudes of both parametric vibration and wind fluctuating vibration are smaller than those of steel cables. It can be concluded from the research that the use of CFRP cables does not change the dynamic characteristics of the vehicle-bridge coupling vibration. Therefore, they can be used in long-span cable-stayed bridges with an excellent mechanical performance.

  5. NONLINEAR ANALYSIS OF CFRP- PRESTRESSED CONCRETE BEAMS SUBJECTED TO INCREMENTAL STATIC LOADING BY FINITE ELEMENTS

    Directory of Open Access Journals (Sweden)

    Husain M. Husain

    2013-05-01

    Full Text Available In this work a program is developed to carry out the nonlinear analysis (material nonlinearity of prestressed concrete beams using tendons of carbon fiber reinforced polymer (CFRP instead of steel. The properties of this material include high strength, light weight, and insusceptibility to corrosion and magnetism. This material is still under investigation, therefore it needs continuous work to make it beneficial in concrete design. Four beams which are tested experimentally by Yan et al. are examined by the developed computer program to reach a certain analytical approach of the design and analysis of such beams because there is no available restrictions or recommendations covering this material in the codes. The program uses the finite element analysis by dividing the beams into isoparametric 20-noded brick elements. The results obtained are good in comparison with experimental results.

  6. Bending Moment Decrease of Reinforced Concrete Beam Supported by Additional CFRP

    Directory of Open Access Journals (Sweden)

    Mykolas Daugevičius

    2011-04-01

    Full Text Available The calculation method of reinforced concrete beam with additional CFRP composite is proposed in this article. This method estimates tangential angular concrete deformations in tensioned beam layers between steel and bonded carbon fiber reinforced polymer. The horizontal slip of CFRP composite reduce beam bending moment capacity. An additional coefficient to reduce CFRP resultant force is necessary for better precision of bending moment capacity. Also, various calculation methods of bending moment capacity are considered. Article in Lithuanian

  7. Effect of CFRP strengthening on the response of RC slabs to hard projectile impact

    Energy Technology Data Exchange (ETDEWEB)

    Almusallam, Tarek; Al-Salloum, Yousef; Alsayed, Saleh; Iqbal, Rizwan; Abbas, Husain, E-mail: abbas_husain@hotmail.com

    2015-05-15

    Highlights: • Studied response of CFRP-strengthened RC slabs under the impact load. • Slabs were tested under the strike of hemispherical steel projectiles at varying impact. • The slabs were analyzed numerically using LS-DYNA. • Strengthening increased the ballistic limit velocity by 18% and perforation energy by 56.7%. • CFRP sheet reduced the crater damage and contained the flying concrete fragments. - Abstract: In this paper impact response of CFRP-strengthened RC panels under the impact of non-deformable projectiles has been presented. The control and CFRP-strengthened RC slab panels were tested under the strike of hemispherical nosed steel projectiles at varying impact velocities. The response of these panels was investigated experimentally as well as numerically. The damage of the slab panels was measured in terms of the penetration depth, formation of cracks, spalling and scabbing areas and fracture of CFRP sheet. This study presents a practical and efficient numerical method for analyzing the impact response of CFRP-strengthened RC structures using LS-DYNA. The CFRP strengthening was found to increase the ballistic limit velocity by 18%, perforation energy of RC slabs by 56.7%, reduce the front crater damage and contains the flying of concrete fragments from the rear face. The maximum impact force occurs at almost same penetration depth for the control and CFRP-strengthened slabs but the restraint provided by CFRP increased the penetration depth by about 1/19.3 of the thickness of slab.

  8. Effect of CFRP strengthening on the response of RC slabs to hard projectile impact

    International Nuclear Information System (INIS)

    Highlights: • Studied response of CFRP-strengthened RC slabs under the impact load. • Slabs were tested under the strike of hemispherical steel projectiles at varying impact. • The slabs were analyzed numerically using LS-DYNA. • Strengthening increased the ballistic limit velocity by 18% and perforation energy by 56.7%. • CFRP sheet reduced the crater damage and contained the flying concrete fragments. - Abstract: In this paper impact response of CFRP-strengthened RC panels under the impact of non-deformable projectiles has been presented. The control and CFRP-strengthened RC slab panels were tested under the strike of hemispherical nosed steel projectiles at varying impact velocities. The response of these panels was investigated experimentally as well as numerically. The damage of the slab panels was measured in terms of the penetration depth, formation of cracks, spalling and scabbing areas and fracture of CFRP sheet. This study presents a practical and efficient numerical method for analyzing the impact response of CFRP-strengthened RC structures using LS-DYNA. The CFRP strengthening was found to increase the ballistic limit velocity by 18%, perforation energy of RC slabs by 56.7%, reduce the front crater damage and contains the flying of concrete fragments from the rear face. The maximum impact force occurs at almost same penetration depth for the control and CFRP-strengthened slabs but the restraint provided by CFRP increased the penetration depth by about 1/19.3 of the thickness of slab

  9. RC Columns Strengthened with Novel CFRP Systems: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Annalisa Napoli

    2015-10-01

    Full Text Available This paper presents an experimental study undertaken to investigate the seismic behavior of full scale square (300 mm × 300 mm reinforced concrete (RC columns strengthened with novel systems employing carbon fiber-reinforced polymers (CFRP wraps. Experimental tests were carried out by subjecting specimens to a constant axial load and a cyclically reversed horizontal force applied in displacement control. Results have allowed for investigating the influence of the used strengthening systems on the specimens’ performance in terms of flexural strength and ductility as well as on the exhibited failure modes. The effectiveness of the studied techniques is also evaluated by comparing the performance of tested specimens with that of companion columns strengthened with alternative CFRP systems investigated in a previous experimental campaign.

  10. Experimental Study on CFRP Strengthened Cold Formed Channel Columns

    Directory of Open Access Journals (Sweden)

    Sreedhar Kalavagunta

    2013-09-01

    Full Text Available Cold-formed steel members usually display local-global buckling interaction which strongly effects the structural strength of columns. Through strengthening web of the members this buckling can be controlled to some extent. In this investigation, Carbon Fibre Reinforced Polymers (CFRP is used for strengthening cold formed steel channel member. This paper presents compression tests of cold-formed plain and CFRP strengthened steel channel section columns. This paper also proposes a design method based on Direct Strength Method provisions specified in American Iron and Steel Institute (AISI, for determining the axial compression strength. Results obtained from the proposed design method are compared with experimental test data and are found to be in good agreement.

  11. Quantitative X-ray determination of CFRP micro structures

    International Nuclear Information System (INIS)

    Beyond imaging the mass distribution of materials by X-ray absorption techniques recent synchrotron and laboratory X-ray refraction techniques provide interface contrast imaging of micro structures. This is of specific relevance to carbon fibre composites (CFRP) which constitute advanced aerospace components. Apart from merely finding isolated flaws like cracks or pores within the natural high interface density only the quantitative measurement of the differences after defined mechanical treatment provides a reliable understanding of the related macroscopic properties. The contribution of the fibre matrix interface of CFRP laminates to the mechanical properties is investigated by relating the mechanical damage to the additional fibre debonding after impact and fatigue. Composites of industrially sized carbon fibres for aerospace applications and of unsized fibres are compared. (orig.)

  12. Evaluation of electrical transverse conductivity of the unidirectional CFRP

    Science.gov (United States)

    Khebbab, Mohamed; Feliachi, Mouloud; El Hadi Latreche, M.

    2016-01-01

    In this paper, a technique for the calculation of the electrical transverse conductivity of unidirectional carbon fiber reinforced polymer (CFRP), based on Markov chains, is proposed. Inspired by the microscopic cross-sectional structure of CFRP, an electrical percolation system is constructed. The effective transverse conductivity is derived from an equivalent conductance of the percolation network. To achieve such a determination, a notion of escape probability associated to absorbing Markov chains is applied. The obtained results are compared with those given by percolation theory; and also with published experimental data. Our results are shown to be in good agreement with the references. Contribution to the topical issue "Numelec 2015 - Elected submissions", edited by Adel Razek

  13. Repair and Strengthening of Reinforced Concrete Structures Using CFRP Plates

    International Nuclear Information System (INIS)

    The infrastructure's increasing decay is frequently combined with the need for upgrading so that structures can meet more stringent design requirements (e.g., increased traffic volumes in bridges exceeding the initial design loads), and hence the aspect of civil engineering infrastructure renewal has received considerable attention over the past few years throughout the world. At the same time, seismic retrofit has become equally important, especially in the areas of high seismic risk. The worldwide acceptance of external plate bonding using CFRP laminates for the repair of under strengthened or damaged reinforced concrete beams is the real incentive for many investigators to devote a great deal of effort to physically understand the response of such beams under externally applied loads. This paper is aimed towards providing a review of the repair and strengthening of the RC concrete structures using CFRP plates along with introducing the basics of the above mentioned technique

  14. Evaluation of Cryogenic CFRP Tank Elements under Pressurized Liquid Hydrogen

    OpenAIRE

    吉田, 誠; Yoshida, Makoto; 須藤, 孝幸; SUDO,Takayuki; 野坂, 正隆; NOSAKA, Masataka

    2001-01-01

    To realize a fully reusable Single-Stage-To-Orbit (SSTO) transportation system, rocket engine performance must be greatly increased and total weight must be drastically reduced. To reduce the weight of the cryogenic tanks which occupy most of the dry weight of the system, it is effective to use lightweight composite materials such as carbon fiber reinforced plastic (CFRP). The goal of the present study was to reduce the weight of the propellant feed system (cryogenic tanks, turbopumps, feed l...

  15. The Cutting Process, Chips and Cutting Forces in Machining CFRP

    DEFF Research Database (Denmark)

    Koplev, A.; Lystrup, Aage; Vorm, T.

    1983-01-01

    The cutting of unidirectional CFRP, perpendicular as well as parallel to the fibre orientation, is examined. Shaping experiments, ‘quick-stop’ experiments, and a new chip preparation technique are used for the investigation. The formation of the chips, and the quality of the machined surface is d...... discussed. The cutting forces parallel and perpendicular to the cutting direction are measured for various parameters, and the results correlated to the formation of chips and the wear of the tool....

  16. Stress-strain model for partial CFRP confined concrete

    OpenAIRE

    Ferreira, Débora R. S. M.; Barros, Joaquim A. O.

    2008-01-01

    Concrete columns requiring strengthening intervention always contain a certain percentage of steel hoops. Applying strips of wet lay-up carbon fiber reinforced polymer (CFRP) sheets in-between the existent steel hoops might, therefore, be an appropriate confinement technique with both technical and economic advantages, when full wrapping of a concrete column is taken as a basis of comparison. To assess the effectiveness of the partial wrapping technique, circular cross section con...

  17. EXPERIMENTAL FIRE BEHAVIOUR OF PRECAST CFRP PRETENSIONED HPSCC SLABS

    OpenAIRE

    Maluk, Cristian; Giovanni P. Terrasi; Bisby, Luke; Stutz, Alex; Hugi, Erich

    2014-01-01

    Optimized concrete elements have been developed using high-performance, self- consolidating, fibre-reinforced concrete (HPSCC) reinforced with high-strength, lightweight, non-corroding pre-stressed carbon fibre reinforced plastic tendons. This new type of thin-walled precast carbon FRP (CFRP) pretensioned HPSCC slab has been used in building façades and is under consideration for a range of other applications in buildings. However, it is well known that the bond strength between both steel an...

  18. An CFRP fabrics as internal reinforcement in concrete beams

    OpenAIRE

    Achintha, M.; Alami, F; Bloodworth, A.G.

    2015-01-01

    This paper presents preliminary results of an experimental programme that investigated mechanical properties of a balanced-symmetric CFRP fabric laminate. Although FRP fabrics have potential to be formed into efficient reinforcement systems that can enable the development of innovative low embodied energy concrete structures, very little research on applications of FRP fabrics has been reported in the literature. In accordance with the classical laminate theory, in a balanced-symmetric lamina...

  19. Structural strengthening with prestressed CFRP strips with gradient anchorage

    OpenAIRE

    Michels, Julien; Sena-Cruz, José; Czaderski, Christoph; Motavalli, Masoud

    2013-01-01

    This paper presents the principle and the application of an innovative anchorage technique for prestressed carbon fiber–reinforced polymer (CFRP) strips in structural strengthening. Additionally, large-scale static loading tests of retrofitted concrete beams are shown. The gradient anchorage, based on the adhesive’s ability to undergo accelerated curing at high temperatures, consists of a purely concrete-adhesive strip connection without any mechanical devices, such as bolts or plates. In a f...

  20. Analysis of nonlinear deformations and damage in CFRP textile laminates

    International Nuclear Information System (INIS)

    Carbon fibre-reinforced polymer (CFRP) textile composites are widely used in aerospace, automotive and construction components and structures thanks to their relatively low production costs, higher delamination and impact strength. They can also be used in various products in sports industry. These products are usually exposed to different in-service conditions such as large bending deformation and multiple impacts. Composite materials usually demonstrate multiple modes of damage and fracture due to their heterogeneity and microstructure, in contrast to more traditional homogeneous structural materials like metals and alloys. Damage evolution affects both their in-service properties and performance that can deteriorate with time. These damage modes need adequate means of analysis and investigation, the major approaches being experimental characterisation, numerical simulations and microtomography analysis. This research deals with a deformation behaviour and damage in composite laminates linked to their quasi-static bending. Experimental tests are carried out to characterise the behaviour of woven CFRP material under large-deflection bending. Two-dimensional finite element (FE) models are implemented in the commercial code Abaqus/Explicit to study the deformation behaviour and damage in woven CFRP laminates. Multiple layers of bilinear cohesive-zone elements are employed to model the onset and progression of inter-ply delamination process. X-ray Micro-Computed Tomography (MicroCT) analysis is carried out to investigate internal damage mechanisms such as cracking and delaminations. The obtained results of simulations are in agreement with experimental data and MicroCT scans.

  1. Development of High Performance CFRP/Metal Active Laminates

    Science.gov (United States)

    Asanuma, Hiroshi; Haga, Osamu; Imori, Masataka

    This paper describes development of high performance CFRP/metal active laminates mainly by investigating the kind and thickness of the metal. Various types of the laminates were made by hot-pressing of an aluminum, aluminum alloys, a stainless steel and a titanium for the metal layer as a high CTE material, a unidirectional CFRP prepreg as a low CTE/electric resistance heating material, a unidirectional KFRP prepreg as a low CTE/insulating material. The aluminum and its alloy type laminates have almost the same and the highest room temperature curvatures and they linearly change with increasing temperature up to their fabrication temperature. The curvature of the stainless steel type jumps from one to another around its fabrication temperature, whereas the titanium type causes a double curvature and its change becomes complicated. The output force of the stainless steel type attains the highest of the three under the same thickness. The aluminum type successfully increased its output force by increasing its thickness and using its alloys. The electric resistance of the CFRP layer can be used to monitor the temperature, that is, the curvature of the active laminate because the curvature is a function of temperature.

  2. Analysis of nonlinear deformations and damage in CFRP textile laminates

    Energy Technology Data Exchange (ETDEWEB)

    Ullah, H; Harland, A R; Silberschmidt, V V [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Leicester-shire, LE11 3TU (United Kingdom); Lucas, T; Price, D, E-mail: H.Ullah@lboro.ac.uk [Adidas AG, Herzogenaruch (Germany)

    2011-07-19

    Carbon fibre-reinforced polymer (CFRP) textile composites are widely used in aerospace, automotive and construction components and structures thanks to their relatively low production costs, higher delamination and impact strength. They can also be used in various products in sports industry. These products are usually exposed to different in-service conditions such as large bending deformation and multiple impacts. Composite materials usually demonstrate multiple modes of damage and fracture due to their heterogeneity and microstructure, in contrast to more traditional homogeneous structural materials like metals and alloys. Damage evolution affects both their in-service properties and performance that can deteriorate with time. These damage modes need adequate means of analysis and investigation, the major approaches being experimental characterisation, numerical simulations and microtomography analysis. This research deals with a deformation behaviour and damage in composite laminates linked to their quasi-static bending. Experimental tests are carried out to characterise the behaviour of woven CFRP material under large-deflection bending. Two-dimensional finite element (FE) models are implemented in the commercial code Abaqus/Explicit to study the deformation behaviour and damage in woven CFRP laminates. Multiple layers of bilinear cohesive-zone elements are employed to model the onset and progression of inter-ply delamination process. X-ray Micro-Computed Tomography (MicroCT) analysis is carried out to investigate internal damage mechanisms such as cracking and delaminations. The obtained results of simulations are in agreement with experimental data and MicroCT scans.

  3. Analysis of nonlinear deformations and damage in CFRP textile laminates

    Science.gov (United States)

    Ullah, H.; Harland, A. R.; Lucas, T.; Price, D.; Silberschmidt, V. V.

    2011-07-01

    Carbon fibre-reinforced polymer (CFRP) textile composites are widely used in aerospace, automotive and construction components and structures thanks to their relatively low production costs, higher delamination and impact strength. They can also be used in various products in sports industry. These products are usually exposed to different in-service conditions such as large bending deformation and multiple impacts. Composite materials usually demonstrate multiple modes of damage and fracture due to their heterogeneity and microstructure, in contrast to more traditional homogeneous structural materials like metals and alloys. Damage evolution affects both their in-service properties and performance that can deteriorate with time. These damage modes need adequate means of analysis and investigation, the major approaches being experimental characterisation, numerical simulations and microtomography analysis. This research deals with a deformation behaviour and damage in composite laminates linked to their quasi-static bending. Experimental tests are carried out to characterise the behaviour of woven CFRP material under large-deflection bending. Two-dimensional finite element (FE) models are implemented in the commercial code Abaqus/Explicit to study the deformation behaviour and damage in woven CFRP laminates. Multiple layers of bilinear cohesive-zone elements are employed to model the onset and progression of inter-ply delamination process. X-ray Micro-Computed Tomography (MicroCT) analysis is carried out to investigate internal damage mechanisms such as cracking and delaminations. The obtained results of simulations are in agreement with experimental data and MicroCT scans.

  4. Damage monitoring of CFRP retrofit using optical fiber sensors

    Science.gov (United States)

    Joshi, Kunal; Breaux Frketic, Jolie; Olawale, David; Dickens, Tarik

    2015-04-01

    With nearly 25% of bridge infrastructure deemed deficient, repair of concrete structures is a critical need. FRP materials as thin laminates or fabrics are appearing to be an ideal alternative to traditional repair technology, because of their high strength to weight ratios and stiffness to weight ratios. In addition, FRP materials offer significant potential for lightweight, high strength, cost-effective and durable retrofit. One drawback of using CFRP retrofitting is its brittle-type failure; caused by its nearly linear elastic nature of the stress-strain behavior. This causes a strength reduction of the retrofitted member, thus the health of the retrofit applied on the structure becomes equally important to sustain the serviceability of the structure. This paper provides a system to monitor damage on the CFRP retrofits through optical fiber sensors which are woven into the structure to provide damage sensing. Precracked reinforced concrete beams were retrofitted using CFRP laminates with the most commonly used FRP application technique. The beams were tested under constant stress to allow the retrofitting to fail while evaluating the performance of the sensing system. Debonding failure modes at a stress of 9 MPa were successfully detected by TL optical fiber sensors in addition to detection during flexural failure. Real-time failure detection of FRP strengthened beams was successfully achieved and the retrofit damage-monitoring scheme aims at providing a tool to reduce the response time and decision making involved in maintenance of deficient structures.

  5. Consolidated Fuel Reprocessing Program. Progress report, January 1 to March 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Unger, W.E. (comp.)

    1979-06-01

    On Oct. 1, 1978, a transition phase was begun to concentrate all US fuel reprocessing research in one major program, the Consolidated Fuel Reprocessing Program (CFRP). The CFRP is organized into the following: process R and D, engineering research, engineering systems, technical support, HTGR fuel reprocessing, and pyrochemical and dry processing methods. Progress is reported in each area. (DLC)

  6. On the role of CFRP reinforcement for wood beams stiffness

    Science.gov (United States)

    Ianasi, A. C.

    2015-11-01

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

  7. Interlaminar Fracture Toughness of CFRP Laminates Incorporating Multi-Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Elisa Borowski

    2015-06-01

    Full Text Available Carbon fiber reinforced polymer (CFRP laminates exhibit limited fracture toughness due to characteristic interlaminar fiber-matrix cracking and delamination. In this article, we demonstrate that the fracture toughness of CFRP laminates can be improved by the addition of multi-walled carbon nanotubes (MWCNTs. Experimental investigations and numerical modeling were performed to determine the effects of using MWCNTs in CFRP laminates. The CFRP specimens were produced using an epoxy nanocomposite matrix reinforced with carboxyl functionalized multi-walled carbon nanotubes (COOH–MWCNTs. Four MWCNTs contents of 0.0%, 0.5%, 1.0%, and 1.5% per weight of the epoxy resin/hardener mixture were examined. Double cantilever beam (DCB tests were performed to determine the mode I interlaminar fracture toughness of the unidirectional CFRP composites. This composite material property was quantified using the critical energy release rate, GIC. The experimental results show a 25%, 20%, and 17% increase in the maximum interlaminar fracture toughness of the CFRP composites with the addition of 0.5, 1.0, and 1.5 wt% MWCNTs, respectively. Microstructural investigations using Fourier transform infrared (FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS verify that chemical reactions took place between the COOH–MWCNTs and the epoxy resin, supporting the improvements experimentally observed in the interlaminar fracture toughness of the CFRP specimens containing MWCNTs. Finite element (FE simulations show good agreement with the experimental results and confirm the significant effect of MWCNTs on the interlaminar fracture toughness of CFRP.

  8. The influence of temperature variations on ultrasonic guided waves in anisotropic CFRP plates.

    Science.gov (United States)

    Putkis, O; Dalton, R P; Croxford, A J

    2015-07-01

    Carbon Fibre Reinforced Polymer (CFRP) materials are lightweight and corrosion-resistant and therefore are increasingly used in aerospace, automotive and construction industries. In Structural Health Monitoring (SHM) applications of CFRP materials, ultrasonic guided waves potentially offer large area inspection or inspection from a remote location. This paper addresses the effect of temperature variation on guided wave propagation in highly anisotropic CFRP materials. Temperature variations cause changes in guided wave velocity that can in turn compromise the baseline subtraction procedures employed by many SHM systems for damage detection. A simple model that describes the dependence of elastic properties of the CFRP plates on temperature is presented in this paper. The model can be used to predict anisotropic velocity changes and baseline subtraction performance under varying thermal conditions. The results produced by the model for unidirectional and 0/90 CFRP plates are compared with experimental measurements. PMID:25812468

  9. Strengthening of steel–concrete composite girders using carbon fibre reinforced polymer (CFRP) plates

    Indian Academy of Sciences (India)

    S M Mosavi; A Sadeghi Nik

    2015-02-01

    Applying composites in order to strengthen and renew the infrastructures has globally been accepted. Traditional methods to strengthen the out-of-standard structures are costly, time consuming and requires a lot of labour. Today, new techniques are hired using light and strong substances which also resist against corrosion, known as Carbon Fibre Reinforced Polymer (CFRP) plates. Regarding the high tensile strength and proper module of elasticity, CFRP plates are considered as a suitable alternative to strengthen girders. The behaviour of steel–concrete composite girders being statically loaded and strengthened by CFRP plates in this study. The CFRP plates used in this study have been stuck, with epoxy adhesive, under the tensile sections of three steel girders. The results accompanied with analytical study of moment–curvature and numerical analysis done with ANSYS, show that CFRP plates with epoxy adhesive increases the ultimate loading capacity of steel–concrete composite girder. Plastic stiffness of the girders was also increased.

  10. Use of laser reflection technique for defect detection in CFRP-concrete systems

    Science.gov (United States)

    Qiu, Qiwen; Lau, Denvid

    2016-04-01

    This paper presents a new laser reflection technique which can identify the near-surface defects in concrete structures bonded with carbon fiber reinforced polymer (CFRP). In this study, a laser beam is used to illuminate the surface of CFRP-concrete panel, and the pattern of the laser reflection is recorded by a high resolution digital camera. Under the laser illumination, the surface of the tested object is heated and expanded. The surface expansion can be identified through observing the expanding reflection pattern. Based on our experimental observation, the defect region exhibits much greater expansion of laser reflection pattern than that in intact region. Results also indicate that both the defect area and the defect depth can influence the change of reflection pattern. In view of the measurement principle of the laser reflection technique, it is expected that the application can be further extended to the areas like CFRP-wood structures, CFRP-masonry structures and CFRP-steel structures.

  11. Finite element analysis of frame beams strengthened by CFRP in the structure%CFRP 加固结构中框架梁有限元分析

    Institute of Scientific and Technical Information of China (English)

    刘强; 乔文正; 高树峰

    2015-01-01

    In order to research the influence of performance on RC structure strengthened by CFRP,non-linear analysis is performed on RC frame beams by ANSYS. Research on the mechanical performance of RC frame beams with a rectangle cut is being performed before or after strengthe-ning. The result can be summarized as follows:the mechanical performance of RC frame beams strengthened by CFRP is greatly improved,and the function of the CFRP is used fully.%为了研究 CFRP(碳纤维复合材料)对于结构性能的影响,采用 ANSYS 有限元分析软件对加固工程中的 RC 框架梁进行了非线性分析,研究了 RC 矩形截面框架梁在 CFRP 加固前后的力学性能,研究结果表明:CFRP 加固后的框架梁的力学性能明显提高,CFRP 充分发挥了作用。

  12. Experimental Investigation on Contribution of CFRP Attachment to Durability of Reinforced Concrete Structure Subjected to Chloride Attack

    Institute of Scientific and Technical Information of China (English)

    Chen Fengshan; Zhao Guofan; Pan Deqiang

    2006-01-01

    The function of externally-bonded carbon fiber reinforced polymer (CFRP) in preventing chloride from entering into concrete is verified by experiment. The results show that externally-bonded CFRP can be considered as a part of corrosion prevention system of strengthened concrete structures subjected to chloride ingress, and the contribution of CFRP should be considered in evaluation of durability of reinforced concrete structures with externally-bonded CFRP. With the effective shielding function of CFRP considered, an equation for residual lifetime prediction of concrete structures with externally-bonded CFRP is derived from Ficks dispersion law. CFRP has two functions for coastal concrete structures, including strengthening and increasing durability as part of corrosion prevention system.

  13. Hygromechanical behaviour of CFRP under cyclic humidity loadings

    CERN Document Server

    Hauviller, Claude

    2001-01-01

    Stable lightweight structures are key issues in the design and construction of the LHC high precision particle detectors. This paper presents the results of long term measurements performed on plates manufactured in Carbon Fibre Reinforced Plastics (CFRP), material selected for these structures, subjected to cyclic humidity loadings. Test procedures are detailed; results on moisture absorption are described together with the related displacement measurements. These results indicate that cycling composites in the operating conditions of the LHC trackers does not provoke any major internal damage.

  14. Study on properties of CFRP fabricated by VA-RTM process

    Science.gov (United States)

    Jeoung, Sun Kyoung; Hwang, Ye Jin; Lee, Hyun Wook; Son, Soon Keun; Kim, Hyung Sik; Ha, Jin Uk

    2016-03-01

    Carbon fiber reinforced plastics (CFRP) have a lot of attention from industry and academia due to its excellent mechanical property. It has been used for aircraft, automotive and so on, since it can replace metallic materials and reduce total weight with increased physical properties. However, the manufacturing process and the material cost are still challenging to be commercialized in the automotive market. Therefore, many researchers are trying to minimize materials and process cost for broadening their applications. In this study, thermoset epoxy resins were used for binder of CFRP. Epoxy resins were investigated in order to figure out optimized curing speed under vacuum assisted resin transfer molding (VARTM) processing condition. Mechanical properties of CFRP with different carbon fiber orientation and woven carbon fiber were compared to mathematically simulated results. In order to develop the application of automobile component, reliability tests of CFRP were carried out. Tensile strength of CFRP is increased when the orientation angle between fiber and axis of load was decreased (90°→ 0°). It is considered that epoxy and carbon fiber absorbed the tensile energy because the orientation of fiber and the load bearing are matched with axis direction. In addition, the CFRP automobile engine hood was fabricated by VARTM process. Drop weight impact tests (20kg & 100kg weight) were carried out in order to simulate crash performance of CFRP engine hoods.

  15. Low temperature gamma ray irradiation effects on polymer materials (4)-gas analysis of GFRP and CFRP

    International Nuclear Information System (INIS)

    Gas analysis was carried out at RT after gamma-irradiation at room temperature and 77K for glass fiber reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP) having the same epoxy resin matrix. Gas yield from CFRP was less than that from GFRP at RT, but comparable at 77 K. The yields of CO and CO2 showed a large dependence on the irradiation temperature, i.e. they were much less at 77 K. Radiation resistance of GFRP and CFRP towards 77 K irradiation is expected to be higher than that towards RT irradiation. (author)

  16. On the plastic behaviour of multi directional epoxy-bolted CFRP laminates

    DEFF Research Database (Denmark)

    Jensen, Aage; Poulsen, Ervin

    2004-01-01

    The second generation of CFRP laminate has recently been developed. It is a multi directional CFRP laminate, i.e. a laminate with carbon fibres having several directions other than the first generation. The paper describes the laboratory tests carried out in order to develop anchorage devices for...... such multi directional CFRP laminates which are epoxy-bonded and bolted or nailed to the concrete substrate for the purpose of strengthening against failure caused by bending. The tests were carried out at the Technical University of Denmark, IABM and Byg-DTU...

  17. Ultrasonic Approach of Rayleigh Pitch-Catch Contact Ultrasound Waves on CFRP Laminated Composites

    Institute of Scientific and Technical Information of China (English)

    In-Young Yang; Kwang-Hee Im; Uk Heo; David K Hsu; Je-Woong Park; Hak-Joon Kim; Sung-Jin Song

    2008-01-01

    CFRP (carbon fiber reinforced plastics) composite materials have wide applicability because of their inherent design flexibility and improved material properties. However, impacted composite structures have 50%-75% less strength than undamaged structures. In this work, a CFRP composite material was nondestructively characterized in order to ensure product quality and structural integrity of CFRP and one-sided pitch-catch technique was developed to measure impacted-damaged area by using an automated-data acquisition system in an immersion tank. A pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave under defect conditions in the composite.

  18. Development of CFRP Mirrors for Space Telescopes Using Replica Technique

    Science.gov (United States)

    Utsunomiya, Shin; Kamiya, Tomohiro; Shimizu, Ryuzo

    2012-07-01

    Ultra-lightweight and high-accuracy CFRP (Carbon Fiber Reinforced Plastics) mirrors for space telescopes have developed and their feasibility for ultrared applications was demonstrated. The CTE (Coefficient of Thermal Expansion) of the all-CFRP sandwich panels was tailored in ±1x10-7/K. The surface accuracy of mirrors of 150 mm in diameter was 0.8 μm RMS (Root Mean Square) as fabricated and the surface smoothness was improved to 5 nm RMS. The surface of front face skins of sandwich panels was coated with epoxy resin and surface accuracy and smoothness were transcribed from an optically-polished glass tool of λ/20 accuracy by replica technique. Surface preciseness was measured before and after replica coating using a 3D optical profiler of white light interferometer. Observed patterns of the asperity of mirror surfaces were classified into four categories, overall warping and line patterns of fiber tows and core patterns and print-through of individual fibers. Replica improved all kinds of asperity.

  19. Damage in woven CFRP laminates subjected to low velocity impacts

    International Nuclear Information System (INIS)

    Carbon fabric-reinforced polymer (CFRP) composites used in sports products can be exposed to different in-service conditions such as large dynamic bending deformations caused by impact loading. Composite materials subjected to such loads demonstrate various damage modes such as matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution in these materials affects both their in-service properties and performance that can deteriorate with time. These processes need adequate means of analysis and investigation, the major approaches being experimental characterisation and non-destructive examination of internal damage in composite laminates. This research deals with a deformation behaviour and damage in woven composite laminates due to low-velocity dynamic out-of-plane bending. Experimental tests are carried out to characterise the behaviour of such laminates under large-deflection dynamic bending in un-notched specimens in Izod tests using a Resil Impactor. A series of low-velocity impact tests is carried out at various levels of impact energy to assess the energy absorbed and force-time response of CFRP laminates. X-ray micro computed tomography (micro-CT) is used to investigate material damage modes in the impacted specimens. X-ray tomographs revealed that through-thickness matrix cracking, inter-ply delamination and intra-ply delamination, such as tow debonding and fabric fracture, were the prominent damage modes.

  20. Damage in woven CFRP laminates subjected to low velocity impacts

    Science.gov (United States)

    Ullah, H.; Abdel-Wahab, A. A.; Harland, A. R.; Silberschmidt, V. V.

    2012-08-01

    Carbon fabric-reinforced polymer (CFRP) composites used in sports products can be exposed to different in-service conditions such as large dynamic bending deformations caused by impact loading. Composite materials subjected to such loads demonstrate various damage modes such as matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution in these materials affects both their in-service properties and performance that can deteriorate with time. These processes need adequate means of analysis and investigation, the major approaches being experimental characterisation and non-destructive examination of internal damage in composite laminates. This research deals with a deformation behaviour and damage in woven composite laminates due to low-velocity dynamic out-of-plane bending. Experimental tests are carried out to characterise the behaviour of such laminates under large-deflection dynamic bending in un-notched specimens in Izod tests using a Resil Impactor. A series of low-velocity impact tests is carried out at various levels of impact energy to assess the energy absorbed and force-time response of CFRP laminates. X-ray micro computed tomography (micro-CT) is used to investigate material damage modes in the impacted specimens. X-ray tomographs revealed that through-thickness matrix cracking, inter-ply delamination and intra-ply delamination, such as tow debonding and fabric fracture, were the prominent damage modes.

  1. Strengthening of Corroded Reinforced SCC-RAP Members with CFRP

    Directory of Open Access Journals (Sweden)

    Ahmed Abdel-Mohti

    2016-01-01

    Full Text Available Corrosion is one of the major problems affecting the durability of reinforced concrete (RC structures. This paper investigates the effect of rebar corrosion on the performance of reinforced self-consolidating concrete (SCC members and the effectiveness of repair. A control RC member, which has no corrosion problem, was prepared to compare against corroded and repaired members. A number of reinforced concrete members having up to 50% corrosion level were constructed and tested to study the effect of corrosion on the structural performance of RC members. The beams with corrosion problem were repaired using carbon fiber reinforced polymer (CFRP sheets and U-wraps. All of the beams constructed, which are either not repaired or repaired, in this study were tested under two static line loads until failure. The effect of corrosion and effectiveness of repairing technique were assessed by evaluating the performance in terms of load carrying capacity, deflection, and ductility. Test results revealed that as the corrosion level increases, the loss in load carrying capacity increases. Repairing using CFRP improved the performance of corroded members. For example, when 50% corrosion level was achieved, the beam lost approximately 57% of its load carrying capacity, but when it was repaired, it recovered about 42% of its load carrying capacity.

  2. DELAMINATION PREDICTION IN DRILLING OF CFRP COMPOSITES USING ARTIFICIAL NEURAL NETWORK

    Directory of Open Access Journals (Sweden)

    K. PALANIKUMAR

    2011-04-01

    Full Text Available Carbon fibre reinforced plastic (CFRP materials play a major role in the applications of aeronautic, aerospace, sporting and transportation industries. Machining is indispensible and hence drilling of CFRP materials is considered in this present study with respect to spindle speed in rpm, drill size in mm and feed in mm/min. Delamination is one of the major defects to be dealt with. The experiments are carried out using computer numerical control machine and the results are applied to an artificial neural network (ANN for the prediction of delamination factor at the exit plane of the CFRP material. It is found that ANN model predicts the delamination for any given set of machining parameters with a maximum error of 0.81% and a minimum error of 0.03%. Thus an ANN model is highly suitable for the prediction of delamination in CFRP materials.

  3. Analytical evaluation of seismic performance of non-ductile RC frames retrofitted using CFRP composites

    OpenAIRE

    Wang, ZY; Wang, DY; Pan, XL; Smith, ST

    2012-01-01

    The objective of this study is to evaluate the effectiveness of different CFRP rehabilitation schemes in promoting the seismic performance of existing non-ductile RC frames. Three nonductile RC frames with different heights representing low-, medium-, and high-rise buildings were investigated. Six typical rehabilitation patterns using CFRP composites were considered and the static pushover and dynamic time-history analyses were conducted for predicting the seismic behavior of frames before an...

  4. Bond Strength Degradation for CFRP and Steel reinforcing Bars in Concrete at Elevated Temperature

    OpenAIRE

    Maluk, Cristian; Bisby, Luke; Terrasi, Giovanni; Green, Mark

    2011-01-01

    Novel concrete elements are emerging utilizing high performance self-consolidating concrete (HPSCC) reinforced with high-strength, lightweight, and non-corroding carbon fiber reinforced polymer (CFRP) prestressed reinforcement. The fire performance of these elements must be understood before they can be used with confidence. In particular, the bond performance of the novel CFRP reinforcement at elevated temperatures requires investigation. This paper examines the bond performance of a specifi...

  5. Degradation characteristic of CFRP by thermal aging, ultraviolet-ray irradiation and γ-ray irradiation

    International Nuclear Information System (INIS)

    The degradation characteristic in the thermal aging, ultraviolet-ray irradiated and γ-ray irradiated CFRP and epoxy resin was investigated. The degradation behavior of the thermomechanical properties of CFRP and epoxy resin is analyzed with the dynamic mechanical analyzer (DMA) and the formation of oxidative products is measured with the infrared spectrum (IR). It is concluded that the difference of the degradation mechanism by the environments is caused by the change of density of crosslinks. (author)

  6. Three-dimensional reconstruction of fracture surfaces of CFRP type composite materials; Reconstrucao tridimensional de superficies de fratura de materias compositos do tipo CFRP

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, Raquel de Moraes

    2009-07-01

    The three-dimensional reconstruction of fracture surfaces of CFRP type composite materials is presented in this work as a possible method for the fractographic analysis of this material, whose rupture surface can present an accentuated roughness, with great variation in height. Two methods are presented for this purpose: the reconstruction for variable focus, carried through with images of optic microscopy and the reconstruction for parallax, carried through with pair of stereo images, obtained by means of scanning electronic microscopy. An evaluation is carried through for each one of the two methods, having argued its limits and the efficiency of each one of them, before the difficulties of analysis of unidirectional and multidirectional composite materials. The method of variable focus presented an excellent reconstruction result, but it has the need of a great number of images, spent time of the instrument and magnifying limit of the images as factors to be considered in the choice of better method. The tilting of the specimen, during the parallax method, discloses alterations in the histograms of the images acquired in the clockwise direction that limit the use of the method for materials with high roughness. The acquiring of images in only one direction and the construction of a region of interest, located in the center of the image are suggestions to turn the method most including. The linearity of the projections of features in the inclined image also suggests the possibility to carry through the reconstruction using, instead of only two, multiple images gotten in the counter-clockwise direction. The alterations proposals to modify the routine, are suggested so that the program can be applied in a more comprehensive form, independent of the quality of the observed fracture surface. (author)

  7. Strengthening an in-service reinforcement concrete bridge with prestressed CFRP bars

    Institute of Scientific and Technical Information of China (English)

    Hai-long WANG; Wei-liang JIN; David J.CLELAND; Ai-hui ZHANG

    2009-01-01

    Carbon fiber reinforced polymer(CFRP)bars were prestressed for the structural strengthening of 8 T-shaped rein-forced concrete (RC)beams of a 21-year-old bridge in China.The ultimate bearing capacity of the existing bridge after retrofit was discussed on the basis of concrete structures theory.The flexural strengths of RC beams strengthened with CFRP bars were controlled by the failure of concrete in compression and a prestressing method was applied in the retrofit.The field construction processes of strengthening with CFRP bars-including grouting cracks,cutting groove,grouting epoxy and embedding CFRP bars,surface treating,banding with the U-type CFRP sheets,releasing external prestressed steel tendons-were introduced in detail.In order to evaluate the effectiveness of this strengthening method,field tests using vehicles as live load were applied before and after the retrofit.The test results of deflection and concrete strain of the T-shaped beams with and without strengthening show that the capacity of the repaired bridge,including the bending strength and stiffness,is enhanced.The measurements of crack width also indicate that this strengthening method can enhance the durability of bridges.Therefore,the proposed strengthening technology is feasible and effective.

  8. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    Science.gov (United States)

    Alferjani, M. B. S.; Samad, A. A. Abdul; Elrawaff, Blkasem S.; Elzaroug, Omer; Mohamad, Noridah

    2015-05-01

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results.

  9. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    International Nuclear Information System (INIS)

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results

  10. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    Energy Technology Data Exchange (ETDEWEB)

    Alferjani, M. B. S.; Samad, A. A. Abdul; Mohamad, Noridah [Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia, Batu Pahat (Malaysia); Elrawaff, Blkasem S.; Elzaroug, Omer [Faculty of Civil Engineering Omar Al Mukhtar University, Bayda, Libya, Africa (Libya)

    2015-05-15

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results.

  11. Test temperature dependence of bending strength of CFRP irradiated with electron beam

    International Nuclear Information System (INIS)

    Carbon fiber-reinforced plastics have the small specific gravity and high specific strength and specific modulus of elasticity as compared with metals, therefore, they are indispensable as the structural materials for aviation and space parts. However, the structural materials for space use are exposed to the environment of several tens MGy of radiation and the repetition of high temperature and low temperature, accordingly also the radiation resistance and heat resistance are required. In this study, the test temperature dependence of the bending strength of CFRP and the relation of the cause of strength lowering to the thickness of CFRP were examined, and the results are reported. As for the carbon fibers for reinforcement, the plain woven cloth of Treca T300 was used, and the matrix resin was tetraglycidyl-4,4'-diamino diphenyl methane being hardened with diamino diphenyl sulfon. The laminated sheets of 2 mm, 0.9 mm and 0.3 mm thickness of the CFRP were used. Irradiation was carried out with an electron accelerator at dose rate of 5 kGy/sec until the prescribed absorbed dose has been attained. The bending test was carried out by three-point bending in the range from room temperature to 180 degC. The high temperature mechanical properties of the irradiated CFRP were superior to those of the CFRP without irradiation. The high temperature mechanical properties depended on aging time at the temperature exceeding the strength inflection point. (K.I.)

  12. Consolidated Fuel Reprocessing Program: National Program Plan, FY 1983

    International Nuclear Information System (INIS)

    This FY 1983 National Program Plan for the Consolidated Fuel Reprocessing Program (CFRP) provides specific guidance from the Department of Energy (DOE) for FY 1983 CFRP activities and a baseline for future year activities. This initial issue of the Plan, which will be updated annually, summarizes program objectives, summary plans and schedules, budget allocations, contractor involvement, and interfaces with other research programs. The National Program Plan is a controlling document for the Technical Program Plan, which is prepared annually by the CFRP at ORNL and is one of a hierarchical group of planning documents. The CFRP is a part of the DOE's program of research and development (R and D) on nuclear fission systems and is directed by the LMFBR Fuel Cycle Projects Division, Office of Spent Fuel Management and Reprocessing Systems at DOE-Headquarters through the Oak Ridge Operations Office (ORO). The strategy of the program is to maintain the capability to commit to a breeder option through a strong R and D program on breeder reprocessing and alternate fuels and fuel cycles to achieve operating and economic advantages

  13. Consolidated Fuel Reprocessing Program. National Program Plan FY 1984

    International Nuclear Information System (INIS)

    This FY 1984 National Program Plan for the Consolidated Fuel Reprocessing Program (CFRP) provides specific guidance from the Department of Energy (DOE) for FY 1984 CFRP activities and a baseline for activities in future years. This is the second issue of the Plan, which is updated anually and summarizes program objectives, summary plans and schedules, budget allocations, contractor involvement, and interfaces with other research programs. The National Program Plan is a controlling document for the Technical Program Plan, which is prepared annually by the CFRP at Oak Ridge National Laboratory (ORNL) and is one of the hierarchical group of planning documents. The CFRP is a part of the DOE's program of research and development (R and D) on nuclear fission systems and is directed by the LMFBR Fuel Cycle Projects Division, Office of Spent Fuel Management and Reprocessing Systems at DOE-Headquarters through the Oak Ridge Operations Office (ORO). The strategy of the program is to maintain the capability to commit to a breeder option through a strong R and D program on breeder reprocessing and alternate fuels and fuel cycles in order to achieve operating and economic advantages

  14. Consolidated Fuel Reprocessing Program. National Program Plan, FY 1985

    International Nuclear Information System (INIS)

    This FY 1985 National Program Plan for the Consolidated Fuel Reprocessing Program (CFRP) provides specific guidance from the Department of Energy (DOE) for FY 1985 CFRP activities and a baseline for activities in future years. This is the third issue of the Plan, which is updated annually and summarizes program objectives, plans, and schedules, budget allocations, contractor involvements, and interfaces with other research programs. The National Program Plan is a controlling document for the Technical Program Plan, which is prepared annually by the CFRP at Oak Ridge National Laboratory (ORNL) and is one of a hierarchical group of planning documents. The CFRP is a part of the DOE's program of research and development (R and D) on nuclear fission systems and is directed by the LMFBR Fuel Cycle Projects Division, Office of Spent Fuel Management and Reprocessing Systems at DOE-Headquarters through the Oak Ridge Operations Office (ORO). The strategy of the program is to maintain the capability to commit to a breeder option through a strong fuel cycle R and D program and international technical exchanges

  15. Infrared thermography for CFRP inspection: computational model and experimental results

    Science.gov (United States)

    Fernandes, Henrique C.; Zhang, Hai; Morioka, Karen; Ibarra-Castanedo, Clemente; López, Fernando; Maldague, Xavier P. V.; Tarpani, José R.

    2016-05-01

    Infrared Thermography (IRT) is a well-known Non-destructive Testing (NDT) technique. In the last decades, it has been widely applied in several fields including inspection of composite materials (CM), specially the fiber-reinforced polymer matrix ones. Consequently, it is important to develop and improve efficient NDT techniques to inspect and assess the quality of CM parts in order to warranty airworthiness and, at the same time, reduce costs of airline companies. In this paper, active IRT is used to inspect carbon fiber-reinforced polymer (CFRP) at laminate with artificial inserts (built-in sample) placed on different layers prior to the manufacture. Two optical active IRT are used. The first is pulsed thermography (PT) which is the most widely utilized IRT technique. The second is a line-scan thermography (LST) technique: a dynamic technique, which can be employed for the inspection of materials by heating a component, line-by-line, while acquiring a series of thermograms with an infrared camera. It is especially suitable for inspection of large parts as well as complex shaped parts. A computational model developed using COMSOL Multiphysics® was used in order to simulate the inspections. Sequences obtained from PT and LST were processed using principal component thermography (PCT) for comparison. Results showed that it is possible to detect insertions of different sizes at different depths using both PT and LST IRT techniques.

  16. Matrix phased arrays for the inspection of CFRP-components

    Energy Technology Data Exchange (ETDEWEB)

    Kreutzbruck, M.; Brackrock, D.; Brekow, G.; Montag, H.-J.; Boehm, R.; Illerhaus, B. [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany)

    2014-02-18

    Lightweight components are increasingly used in different industrial sectors such as transportation, energy generation and automotive. This growing field includes different types of CFRP-structures, hybrid materials and glued components showing - compared to their pure metallic counterparts- a significant more complicated structure in terms of internal interfaces and anisotropy of material parameters. In this work we present the use of matrix phased array to increase the amount of obtained information to enhance the inspection quality. We used different types of carbon materials such as 6 mm thick uni- and bidirectional prepreg specimens containing impact damages. The latter were introduced with different energy levels ranging from 1.3 to 7.2 J. By scanning a 2.25 MHz matrix array with 6 × 10 elements above the prepreg surface and using different angels of incidence a complete 3D-image was generated which allows the detection of defects as small as 1mm in a depth of 4 mm. A comparison with conventional approaches show that the signal-to-noise ratio can be highly increased. This enables us to visualize the region of damage within the impact zone, clearly showing the cone-like damage distribution along increasing material depth. The detection quality allows the estimation of the opening angles of the cone shaped damage, which can be used for further evaluation and quantitation of energy dependent impact damages.

  17. Matrix phased arrays for the inspection of CFRP-components

    Science.gov (United States)

    Kreutzbruck, M.; Brackrock, D.; Brekow, G.; Montag, H.-J.; Boehm, R.; Illerhaus, B.

    2014-02-01

    Lightweight components are increasingly used in different industrial sectors such as transportation, energy generation and automotive. This growing field includes different types of CFRP-structures, hybrid materials and glued components showing - compared to their pure metallic counterparts- a significant more complicated structure in terms of internal interfaces and anisotropy of material parameters. In this work we present the use of matrix phased array to increase the amount of obtained information to enhance the inspection quality. We used different types of carbon materials such as 6 mm thick uni- and bidirectional prepreg specimens containing impact damages. The latter were introduced with different energy levels ranging from 1.3 to 7.2 J. By scanning a 2.25 MHz matrix array with 6 × 10 elements above the prepreg surface and using different angels of incidence a complete 3D-image was generated which allows the detection of defects as small as 1mm in a depth of 4 mm. A comparison with conventional approaches show that the signal-to-noise ratio can be highly increased. This enables us to visualize the region of damage within the impact zone, clearly showing the cone-like damage distribution along increasing material depth. The detection quality allows the estimation of the opening angles of the cone shaped damage, which can be used for further evaluation and quantitation of energy dependent impact damages.

  18. NDT evaluation of long-term bond durability of CFRP-structural systems applied to RC highway bridges

    Science.gov (United States)

    Crawford, Kenneth C.

    2016-03-01

    The long-term durability of CFRP structural systems applied to reinforced-concrete (RC) highway bridges is a function of the system bond behavior over time. The sustained structural load performance of strengthened bridges depends on the carbon fiber-reinforced polymer (CFRP) laminates remaining 100 % bonded to concrete bridge members. Periodic testing of the CFRP-concrete bond condition is necessary to sustain load performance. The objective of this paper is to present a non-destructive testing (NDT) method designed to evaluate the bond condition and long-term durability of CFRP laminate (plate) systems applied to RC highway bridges. Using the impact-echo principle, a mobile mechanical device using light impact hammers moving along the length of a bonded CFRP plate produces unique acoustic frequencies which are a function of existing CFRP plate-concrete bond conditions. The purpose of this method is to test and locate CFRP plates de-bonded from bridge structural members to identify associated deterioration in bridge load performance. Laboratory tests of this NDT device on a CFRP plate bonded to concrete with staged voids (de-laminations) produced different frequencies for bonded and de-bonded areas of the plate. The spectra (bands) of frequencies obtained in these tests show a correlation to the CFRP-concrete bond condition and identify bonded and de-bonded areas of the plate. The results of these tests indicate that this NDT impact machine, with design improvements, can potentially provide bridge engineers a means to rapidly evaluate long lengths of CFRP laminates applied to multiple highway bridges within a national transportation infrastructure.

  19. NDT evaluation of long-term bond durability of CFRP-structural systems applied to RC highway bridges

    Science.gov (United States)

    Crawford, Kenneth C.

    2016-06-01

    The long-term durability of CFRP structural systems applied to reinforced-concrete (RC) highway bridges is a function of the system bond behavior over time. The sustained structural load performance of strengthened bridges depends on the carbon fiber-reinforced polymer (CFRP) laminates remaining 100 % bonded to concrete bridge members. Periodic testing of the CFRP-concrete bond condition is necessary to sustain load performance. The objective of this paper is to present a non-destructive testing (NDT) method designed to evaluate the bond condition and long-term durability of CFRP laminate (plate) systems applied to RC highway bridges. Using the impact-echo principle, a mobile mechanical device using light impact hammers moving along the length of a bonded CFRP plate produces unique acoustic frequencies which are a function of existing CFRP plate-concrete bond conditions. The purpose of this method is to test and locate CFRP plates de-bonded from bridge structural members to identify associated deterioration in bridge load performance. Laboratory tests of this NDT device on a CFRP plate bonded to concrete with staged voids (de-laminations) produced different frequencies for bonded and de-bonded areas of the plate. The spectra (bands) of frequencies obtained in these tests show a correlation to the CFRP-concrete bond condition and identify bonded and de-bonded areas of the plate. The results of these tests indicate that this NDT impact machine, with design improvements, can potentially provide bridge engineers a means to rapidly evaluate long lengths of CFRP laminates applied to multiple highway bridges within a national transportation infrastructure.

  20. Evaluation of Seismic Behaviors of Partially Deteriorated Reinforced Concrete Circular Columns Retrofitted with CFRP

    Directory of Open Access Journals (Sweden)

    Dongxu Hou

    2014-01-01

    Full Text Available Deficiency of the concrete strength in some regions of reinforced concrete (RC columns in practice may weaken the seismic behaviors of columns. Its effects on RC columns should be well understood. This paper aims to investigate the influences of deteriorated segment on the seismic behaviors of partially deteriorated RC columns and attempts to recover the seismic behaviors of partially deteriorated columns with Carbon Fiber Reinforced Polymer (CFRP composites. A finite element analysis was carried out to simulate the seismic behaviors of CFRP-confined partially deteriorated RC columns. The numerical results were verified by the laboratory tests of six specimens. Based on the finite element results, the failure location of partially deteriorated columns in an earthquake was predicted, and the effectiveness of CFRP retrofitted on partially deteriorated columns was evaluated.

  1. Finite element analysis when orthogonal cutting of hybrid composite CFRP/Ti

    Science.gov (United States)

    Xu, Jinyang; El Mansori, Mohamed

    2015-07-01

    Hybrid composite, especially CFRP/Ti stack, is usually considered as an innovative structural configuration for manufacturing the key load-bearing components in modern aerospace industry. This paper originally proposed an FE model to simulate the total chip formation process dominated the hybrid cutting operation. The hybrid composite model was established based on three physical constituents, i.e., Ti constituent, interface and CFRP constituent. Different constitutive models and damage criteria were introduced to replicate the interrelated cutting behaviour of the stack material. The CFRP/Ti interface was modelled as a third phase through the concept of cohesive zone (CZ). Particular attention was made on the comparative studies of the influence of different cutting-sequence strategies on the machining responses induced in hybrid stack cutting. The numerical results emphasized the pivotal role of cutting-sequence strategy on the various machining induced responses including cutting-force generation, machined surface quality and induced interface damage.

  2. Analysis of laser ablation dynamics of CFRP in order to reduce heat affected zone

    Science.gov (United States)

    Sato, Yuji; Tsukamoto, Masahiro; Nariyama, Tatsuya; Nakai, Kazuki; Matsuoka, Fumihiro; Takahashi, Kenjiro; Masuno, Shinichiro; Ohkubo, Tomomasa; Nakano, Hitoshi

    2014-03-01

    A carbon fiber reinforced plastic [CFRP], which has high strength, light weight and weather resistance, is attractive material applied for automobile, aircraft and so on. The laser processing of CFRP is one of suitable way to machining tool. However, thermal affected zone was formed at the exposure part, since the heat conduction property of the matrix is different from that of carbon fiber. In this paper, we demonstrated that the CFRP plates were cut with UV nanosecond laser to reduce the heat affected zone. The ablation plume and ablation mass were investigated by laser microscope and ultra-high speed camera. Furthermore, the ablation model was constructed by energy balance, and it was confirmed that the ablation rate was 0.028 μg/ pulse in good agreement with the calculation value of 0.03 μg/ pulse.

  3. Low-velocity impact damage characterization of carbon fiber reinforced polymer (CFRP) using infrared thermography

    Science.gov (United States)

    Li, Yin; Zhang, Wei; Yang, Zheng-wei; Zhang, Jin-yu; Tao, Sheng-jie

    2016-05-01

    Carbon fiber reinforced polymer (CFRP) after low-velocity impact is detected using infrared thermography, and different damages in the impacted composites are analyzed in the thermal maps. The thermal conductivity under pulse stimulation, frictional heating and thermal conductivity under ultrasonic stimulation of CFRP containing low-velocity impact damage are simulated using numerical simulation method. Then, the specimens successively exposed to the low-velocity impact are respectively detected using the pulse infrared thermography and ultrasonic infrared thermography. Through the numerical simulation and experimental investigation, the results obtained show that the combination of the above two detection methods can greatly improve the capability for detecting and evaluating the impact damage in CFRP. Different damages correspond to different infrared thermal images. The delamination damage, matrix cracking and fiber breakage are characterized as the block-shape hot spot, line-shape hot spot,

  4. Numerical Simulation and Experimental Validation of an Integrated Sleeve-Wedge Anchorage for CFRP Rods

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Smith, Scott T.; Täljsten, Björn; Bennitz, Anders; Goltermann, Per; Pedersen, Henning

    2011-01-01

    The tensioning of carbon fibre-reinforced polymer (CFRP) rods for prestressed concrete applications or post-tensioning repair and strengthening has met with mixed success. This is primarily due to limitations inherent in the use of traditional wedge anchors typically used for steel tendons....... Recently, an integrated sleeve-wedge anchorage has been successfully developed specifically for CFRP rods. This paper in turn presents a numerical simulation of the newly developed anchorage using ABAQUS. The three-dimensional finite element (FE) model, which considers material non-linearity, uses...... hexagonal elements for the barrel and CFRP rod and tetrahedral elements for the integrated sleeve-wedge. The simulated barrel surface strains are shown to compare well with optically measured strains, however, the numerical results are shown to be sensitive to the mechanical properties of the anchorage and...

  5. Application of Desalination with CFRP Composite Electrode to Concrete Deteriorated by Chloride Attack

    Science.gov (United States)

    Yamaguchi, Keisuke; Ueda, Takao; Nanasawa, Akira

    As a new rehabilitation technique for recovery both of loading ability and durability of concrete structures deteriorated by chloride attack, desalination (electrochemical chloride removal technique from concrete) using CFRP composite electrode bonding to concrete has been developed. In this study, basic application was tried using small RC specimens, and also application to the large-scale RC beams deteriorated by the chloride attack through the long-term exposure in the outdoors was investigated. As the result of bending test of treated specimens, the decrease of strengthening effect with the electrochemical treatment was observed in the case of small specimens using low absorption rate resin for bonding, on the other hand, in the case of large-scale RC beam using 20% absorption rate resin for bonding CFRP composite electrode, enough strengthening effect was obtained by the bending failure of RC beam with the fracture of CFRP board.

  6. Experimental Study of RC Beams Strengthened with CFRP Sheets Under Sustaining Loads

    Institute of Scientific and Technical Information of China (English)

    WANG Wenwei; LI Guo

    2006-01-01

    Seven reinforced concrete (RC) beams strengthened in flexure using carbon fiber reinforced polymer (CFRP) sheets subjected to different sustaining loads were tested. The effects of initial load and load history on the ultimate strength of strengthened RC beams were examined by externally bonded CFRP sheets. The main experimental parameters included different levels of sustaining load at the time of strengthening, and load history. Experimental results show that sustaining load levels at the time of strengthening have important influences on the ultimate strength of strengthened RC beams. If the initial load is the same, the ultimate strength of RC beams strengthened with CFRP sheets is almost the same regardless of load history at the time of strengthening.

  7. Cutting and drilling of carbon fiber reinforced plastics (CFRP) by 70W short pulse nanosecond laser

    Science.gov (United States)

    Jaeschke, Peter; Stolberg, Klaus; Bastick, Stefan; Ziolkowski, Ewa; Roehner, Markus; Suttmann, Oliver; Overmeyer, Ludger

    2014-02-01

    Continuous carbon fibre reinforced plastics (CFRP) are recognized as having a significant lightweight construction potential for a wide variety of industrial applications. However, a today`s barrier for a comprehensive dissemination of CFRP structures is the lack of economic, quick and reliable manufacture processes, e.g. the cutting and drilling steps. In this paper, the capability of using pulsed disk lasers in CFRP machining is discussed. In CFRP processing with NIR lasers, carbon fibers show excellent optical absorption and heat dissipation, contrary to the plastics matrix. Therefore heat dissipation away from the laser focus into the material is driven by heat conduction of the fibres. The matrix is heated indirectly by heat transfer from the fibres. To cut CFRP, it is required to reach the melting temperature for thermoplastic matrix materials or the disintegration temperature for thermoset systems as well as the sublimation temperature of the reinforcing fibers simultaneously. One solution for this problem is to use short pulse nanosecond lasers. We have investigated CFRP cutting and drilling with such a laser (max. 7 mJ @ 10 kHz, 30 ns). This laser offers the opportunity of wide range parameter tuning for systematic process optimization. By applying drilling and cutting operations based on galvanometer scanning techniques in multi-cycle mode, excellent surface and edge characteristics in terms of delamination-free and intact fiber-matrix interface were achieved. The results indicate that nanosecond disk laser machining could consequently be a suitable tool for the automotive and aircraft industry for cutting and drilling steps.

  8. CFRP strengthening of concrete beams - testing in sub-zero temperature

    DEFF Research Database (Denmark)

    Täljsten, Björn; Carolin, A.

    2007-01-01

    Strengthening structures with epoxy bonded Carbon Fibre-Reinforced Polymer (CFRP) plates and sheets are today a well-known and over the world common used method to improve a structure performance. The composite materials used for strengthening are very light and easy to handle,. have good...... compared to the summer period? In this paper the last issue will be addressed. CFRP strengthen concrete beams have been tested in sub-zero temperature and loaded up to failure. The cold climate tests are then compared with similar beams tested in room climate. From the tests no significantly difference...

  9. SHEAR BEHAVIOUR OF UNIDIRECTIONAL GFRP AND CFRP AT HIGH STRAIN RATES

    OpenAIRE

    P. Kumar; Rai, B.

    1988-01-01

    The dynamic in-plane shear stress-strain behaviour of unidirectional GFRP (glass fibre reinforced plastic) and CFRP (carbon fibre reinforced plastic) has been studied at high strain rates of about 300/s using the Kolsky torsion machine. The shear stress-strain curves at high strain rates exhibit flow of material at constant shear stresses for strains exceeding 3-5% and 5-7% for GFRP and CFRP respectively. The flow stress for each material is only marginally higher over the strength of quasist...

  10. Laser ablation of CFRP using picosecond laser pulses at different wavelengths from UV to IR

    Science.gov (United States)

    Wolynski, Alexander; Herrmann, Thomas; Mucha, Patrick; Haloui, Hatim; L'huillier, Johannes

    Laser processing of carbon fibre reinforced plastics (CFRP) has a great industrial relevance for high performance structural parts in airplanes, machine tools and cars. Through-holes drilled by nanosecond laser pulses show thermal induced molten layers and voids. Recently, picosecond lasers have demonstrated the ability to drill high-efficient and high-quality rivet through-holes. In this paper a high-power picosecond laser system operating at different wavelengths (355 nm, 532 nm and 1064 nm) has been used for CFRP ablation experiments to study the influence of different laser parameters in terms of machining quality and processing time.

  11. Pull-out behavior of CFRP single-strap ground anchors

    OpenAIRE

    Fan, Haifeng; Keller, Thomas; Vassilopoulos, Anastasios

    2016-01-01

    Pull-out experiments were performed on four carbon fiber-reinforced polymer (CFRP) ground anchors simulating their applications in rock and soil. The CFRP tendons used in these anchors comprise a single-strap end on both the ground and air sides. On the ground side, the single-strap end is embedded in a cylinder of high-strength grout which fits into the borehole. In rock applications, the ground-side anchor can be used directly without additional confinement, while in the case of soil, an ad...

  12. Analysis and Fabrication of Paraboloidal CFRP Sandwich Mirrors

    Science.gov (United States)

    Hong, Tayo Steve

    The low areal weight requirements of telescopes in aerospace applications has driven the study on composite mirrors for several years. For example, the primary parabolic mirror in a balloon-borne, Cassegrain telescope required an optical quality better than 30 microns in figure RMS error. A parametric study on composite sandwich mirrors was conducted by using finite element analysis as well as optical analysis. The factors covered the cell sizes, core materials, core thicknesses, face layups, and support configurations. Based on theoretical calculations, many high quality spherical composite sandwich mirrors were generated by using a non-heat curing process. The CFRP faces and Nomex core were chosen as the baseline materials for mirror fabrication due to their high strength and low weight. The proposed replication method applied an interface layer between face and surface coat to eliminate print -through problems. Many important goals have been realized in those mirror samples with optical laser interferometer testing. These include the figure RMS error less than 2 microns and the surface RMS error less than 0.05 micron. The areal weights of the mirror samples are less than 7 kg/m ^2. The thermal stability of these mirrors was observed from the optical results with thermal cycling tests. The proposed 2-meter parabolic composite sandwich mirror, with an areal weight of less than 10 kg/m ^2, would consist of either (0/90/45/ -45) _{rm S} layup faces with an optimal 3^{' '} core or (QC) layup faces with a total core thickness of 5 inches. Both a ring support around the equator and the 18-point Hindle-type support would lead to the best optical quality under both self weight and thermal loading.

  13. Model-based damage evaluation of layered CFRP structures

    Science.gov (United States)

    Munoz, Rafael; Bochud, Nicolas; Rus, Guillermo; Peralta, Laura; Melchor, Juan; Chiachío, Juan; Chiachío, Manuel; Bond, Leonard J.

    2015-03-01

    An ultrasonic evaluation technique for damage identification of layered CFRP structures is presented. This approach relies on a model-based estimation procedure that combines experimental data and simulation of ultrasonic damage-propagation interactions. The CFPR structure, a [0/90]4s lay-up, has been tested in an immersion through transmission experiment, where a scan has been performed on a damaged specimen. Most ultrasonic techniques in industrial practice consider only a few features of the received signals, namely, time of flight, amplitude, attenuation, frequency contents, and so forth. In this case, once signals are captured, an algorithm is used to reconstruct the complete signal waveform and extract the unknown damage parameters by means of modeling procedures. A linear version of the data processing has been performed, where only Young modulus has been monitored and, in a second nonlinear version, the first order nonlinear coefficient β was incorporated to test the possibility of detection of early damage. The aforementioned physical simulation models are solved by the Transfer Matrix formalism, which has been extended from linear to nonlinear harmonic generation technique. The damage parameter search strategy is based on minimizing the mismatch between the captured and simulated signals in the time domain in an automated way using Genetic Algorithms. Processing all scanned locations, a C-scan of the parameter of each layer can be reconstructed, obtaining the information describing the state of each layer and each interface. Damage can be located and quantified in terms of changes in the selected parameter with a measurable extension. In the case of the nonlinear coefficient of first order, evidence of higher sensitivity to damage than imaging the linearly estimated Young Modulus is provided.

  14. Fiber-Optic-Based Pressure and Residual Strain Monitoring in CFRP Bonding Process: Toward Realization of Secondary Bonding in CFRP Aircraft Structures

    OpenAIRE

    Minakuchi, Shu; Uhira, Keigo; TERADA, Yutaka; Takeda, Nobuo; Saito, Nozomi; Shimizu, Takayuki

    2014-01-01

    Applying secondary bonding to places where carbon fiber reinforced plastic (CFRP) structures are conventionally bolted leads to significant cost and weight saving. However, it has yet to be utilized due to difficulties in quality control. Lack of local pressure in bonding process has detrimental influence on the quality of the cured adhesive layer. Pressure detection is hence a key for controlling bonding quality, and a new quality assurance technique is urgently needed. This study establishe...

  15. Laser drilling of carbon fiber reinforced plastics (CFRP) by picosecond laser pulses: comparative study of different drilling tools

    Science.gov (United States)

    Herrmann, T.; Stolze, M.; L'huillier, J.

    2014-03-01

    Carbon fiber reinforced plastic (CFRP) as a lightweight material with superior properties is increasingly being used in industrial manufacturing. Using ultrashort laser pulses can improve the quality in cutting or drilling applications, but at high power levels it is more complicated to maintain the accuracy and precision in CFRP drilling. According to the application requirements for the extent of the heat affected zone, the geometric precision and the productivity different drilling tools can be used. Therefore we report on the application of three different beam delivery systems to drilling processes of CFRP: Galvanometer scanner, trepanning head and diffractive optical elements.

  16. Three-dimensional reconstruction of fracture surfaces of CFRP type composite materials

    International Nuclear Information System (INIS)

    The three-dimensional reconstruction of fracture surfaces of CFRP type composite materials is presented in this work as a possible method for the fractographic analysis of this material, whose rupture surface can present an accentuated roughness, with great variation in height. Two methods are presented for this purpose: the reconstruction for variable focus, carried through with images of optic microscopy and the reconstruction for parallax, carried through with pair of stereo images, obtained by means of scanning electronic microscopy. An evaluation is carried through for each one of the two methods, having argued its limits and the efficiency of each one of them, before the difficulties of analysis of unidirectional and multidirectional composite materials. The method of variable focus presented an excellent reconstruction result, but it has the need of a great number of images, spent time of the instrument and magnifying limit of the images as factors to be considered in the choice of better method. The tilting of the specimen, during the parallax method, discloses alterations in the histograms of the images acquired in the clockwise direction that limit the use of the method for materials with high roughness. The acquiring of images in only one direction and the construction of a region of interest, located in the center of the image are suggestions to turn the method most including. The linearity of the projections of features in the inclined image also suggests the possibility to carry through the reconstruction using, instead of only two, multiple images gotten in the counter-clockwise direction. The alterations proposals to modify the routine, are suggested so that the program can be applied in a more comprehensive form, independent of the quality of the observed fracture surface. (author)

  17. Strengthening of old metallic structures in fatigue with prestressed and non-prestressed CFRP laminates

    DEFF Research Database (Denmark)

    Täljsten, Björn; Hansen, Christian Skodborg; Schmidt, Jacob Wittrup

    2009-01-01

    Test results and theoretical considerations on four different configurations of strengthened old steel plates with a centre notch loaded in fatigue are presented in this paper. The main interest of the research was to improve fatigue life by adhesive bonding of CFRP laminates on the steel surface...

  18. Analysis of the Dynamic Response in Blast-Loaded CFRP-Strengthened Metallic Beams

    Directory of Open Access Journals (Sweden)

    Zhenyu Wang

    2013-01-01

    Full Text Available Carbon fiber-reinforced polymer composites (CFRPs are good candidates in enhancing the blast resistant performance of vulnerable public buildings and in reinforcing old buildings. The use of CFRP in retrofitting and strengthening applications is traditionally associated with concrete structures. Nevertheless, more recently, there has been a remarkable aspiration in strengthening metallic structures and components using CFRP. This paper presents a relatively simple analytical solution for the deformation and ultimate strength calculation of hybrid metal-CFRP beams when subjected to pulse loading, with a particular focus on blast loading. The analytical model is based on a full interaction between the metal and the FRP and is capable of producing reasonable results in a dynamic loading scenario. A nonlinear finite element (FE model is also developed to reveal the full dynamic behavior of the CFRP-epoxy-steel hybrid beam, considering the detailed effects, that is, large strains, high strain rates in metal, and different failure modes of the hybrid beam. Experimental results confirm the analytical and the FE results and show a strong correlation.

  19. Flexural Strengthening of RC Slabs with Prestressed CFRP Strips Using Different Anchorage Systems

    Directory of Open Access Journals (Sweden)

    José Sena-Cruz

    2015-10-01

    Full Text Available Externally Bonded Reinforcement (EBR technique has been widely used for flexural strengthening of concrete structures by using carbon fiber-reinforced polymers (CFRP. EBR technique offers several structural advantages when the CFRP material is prestressed. This paper presents an experimental and numerical study on reinforced (RC slabs strengthened in flexure with prestressed CFRP strips as a structural strengthening system. The strips are applied as an externally bonded reinforcement (EBR and anchored with either a mechanical or a gradient anchorage. The former foresees metallic anchorage plates fixed to the concrete substrate, while the latter is based on an accelerated epoxy resin curing followed by a segment-wise prestress force decrease at the strip ends. Both anchorage systems, in combination with different CFRP strip geometries, were subjected to static loading tests. It could be demonstrated that the composite strip’s performance is better exploited when prestressing is used, with slightly higher overall load carrying capacities for mechanical anchorages than for the gradient anchorage. The performed investigations by means of a cross-section analysis supported the experimental observation that in case a mechanical anchorage is used, progressive strip debonding changes the fully bonded configuration to an unbonded end-anchored system. The inclusion of defined debonding criteria for both the anchorage zones and free length between the anchorage regions allowed to precisely capture the ultimate loading forces.

  20. Experimental and Theoretical Research on the Compression Performance of CFRP Sheet Confined GFRP Short Pipe

    Directory of Open Access Journals (Sweden)

    Feng Li

    2014-01-01

    Full Text Available The axial compressive strength of unidirectional FRP made by pultrusion is generally quite lower than its axial tensile strength. This fact decreases the advantages of FRP as main load bearing member in engineering structure. A theoretical iterative calculation approach was suggested to predict the ultimate axial compressive stress of the combined structure and analyze the influences of geometrical parameters on the ultimate axial compressive stress of the combined structure. In this paper, the experimental and theoretical research on the CFRP sheet confined GFRP short pole was extended to the CFRP sheet confined GFRP short pipe, namely, a hollow section pole. Experiment shows that the bearing capacity of the GFRP short pipe can also be heightened obviously by confining CFRP sheet. The theoretical iterative calculation approach in the previous paper is amended to predict the ultimate axial compressive stress of the CFRP sheet confined GFRP short pipe, of which the results agree with the experiment. Lastly the influences of geometrical parameters on the new combined structure are analyzed.

  1. Experimental and theoretical research on the compression performance of CFRP sheet confined GFRP short pipe.

    Science.gov (United States)

    Li, Feng; Zhao, Qilin; Chen, Li; Shao, Guojian

    2014-01-01

    The axial compressive strength of unidirectional FRP made by pultrusion is generally quite lower than its axial tensile strength. This fact decreases the advantages of FRP as main load bearing member in engineering structure. A theoretical iterative calculation approach was suggested to predict the ultimate axial compressive stress of the combined structure and analyze the influences of geometrical parameters on the ultimate axial compressive stress of the combined structure. In this paper, the experimental and theoretical research on the CFRP sheet confined GFRP short pole was extended to the CFRP sheet confined GFRP short pipe, namely, a hollow section pole. Experiment shows that the bearing capacity of the GFRP short pipe can also be heightened obviously by confining CFRP sheet. The theoretical iterative calculation approach in the previous paper is amended to predict the ultimate axial compressive stress of the CFRP sheet confined GFRP short pipe, of which the results agree with the experiment. Lastly the influences of geometrical parameters on the new combined structure are analyzed. PMID:24672288

  2. Quantitative analysis of the fibre content distribution in CFRP composites using thermal non-destructive testing

    Directory of Open Access Journals (Sweden)

    G. Wróbel

    2010-01-01

    Full Text Available Purpose: The primary purpose of present study was to determine the fibre content distribution in CFRP composites using thermal non-destructive testing.Design/methodology/approach: The experiments have been performed using transient thermography to obtain the thermograms for CFRP and neat resin specimens. From recorded thermograms, the thermal diffusivity values were determined for all materials under investigation and for two different preheating conditions to verify the effect of preheating conditions on obtained results.Findings: It was found from obtained results that composites with different carbon fibre content had different values of thermal diffusivity. Relationship showed that the thermal diffusivity was a linear function of fibre content in considered materials. It was also found from investigated neat resin specimens that the thermal diffusivity measurement was affected by specimen thickness.Research limitations/implications: Developed relationships between thermal diffusivity and carbon fibre content is not generalized for all types of CFRP composites (manufactured using a different technology or of different thickness, such specific relationships should be determined for any other composite.Practical implications: The results obtained from present experiment would be of great importance in the industrial or laboratory applications to evaluate the fibre content distribution in carbon/epoxy composites.Originality/value: Originality of the present paper is about applying the thermal non-destructive testing to determine the fibre content distribution in CFRP composites.

  3. Experimental and numerical study of the splaying mode crush of CFRP laminates

    OpenAIRE

    Guillon, Damien; Rivallant, Samuel; Barrau, Jean-Jacques; Petiot, Caroline; Thévenet, Pascal; Malherbe, Benoît

    2009-01-01

    Thanks to an innovative plate crushing test fixture, elementary crushing modes of CFRP laminates have been observed and analysed for static and dynamic loading. These analyses enabled to propose a 2D explicit finite element model at mesoscale for the simulation of splaying mode, with a good correlation between model and test data.

  4. Epoxy Enhanced by Recycled Milled Carbon Fibres in Adhesively-Bonded CFRP for Structural Strengthening

    Directory of Open Access Journals (Sweden)

    Chao Wu

    2013-12-01

    Full Text Available This paper investigates the mechanical performance and electrical resistivity of a structural adhesive epoxy enhanced using milled carbon fibre (MCF as well as the bond performance of carbon fibre reinforced polymers (CFRP and steel adhesively bonded joints using the enhanced epoxy. The epoxy was enhanced using such MCFs with different weight ratios of 1.5%, 3% and 5%. Tensile experiments were performed on the original and enhanced epoxy specimens according to ASTM D638. More ductile process failure was found for the epoxy after modification and significant improvements of E-modulus and tensile strength were evidenced when the MCF weight ratio was larger than 1.5%. Scanning electron microscopy (SEM revealed that the failure mechanism of short MCFs pulled out from the epoxy matrix contributed to the enhancement of the mechanical performance of the epoxy. The electrical resistivity of the epoxy with MCF weight ratio of 5% was reduced by at least four orders of magnitude compared to the original epoxy, due to the conductive network formed by MCFs. Steel/CFRP double strap joints (with either CFRP sheets or CFRP laminates were prepared using the enhanced epoxy and then tested in tension, however no obvious increase in joint stiffness or strength was observed.

  5. Application study on the first cable-stayed bridge with CFRP cables in China

    Directory of Open Access Journals (Sweden)

    Kuihua Mei

    2015-08-01

    Full Text Available In order to push forward the development of CFRP cable-stayed bridge and accumulate experiences, the study on the application of the first cable-stayed bridge with CFRP cables in China was carried out. The design essentials of main components of the bridge were introduced and its integral performances, including static properties, dynamic properties and seismic response were analyzed using finite element method. A new bond-type anchorage was developed and the processes of fabricating and installing CFRP cables were elaborated. Based on the results of construction simulation, a tension scheme for bridge was propound. During constructing, the stresses and displacement of girder and pylon, as well as the forces and stresses of cables, were tested. The results indicate that all sections of the bridge could meet the requirements of the ultimate bearing capacity and normal service; the performance of the anchorage is good and the stresses in each cable system are similar; the tested values accord well with the calculated values. Further, creep deformation of the resin in anchorages under service load is not obvious. All these results demonstrate that the first application of CFRP cables in the cable-stayed bridge in China is successful.

  6. The CFRP primary structure of the MIRI instrument onboard the James Webb Space Telescope

    DEFF Research Database (Denmark)

    Jessen, Niels Christian; Nørgaard-Nielsen, Hans Ulrik; Schroll, J;

    2004-01-01

    The design of the Primary Structure of the Mid Infra-Red Instrument (MIRI) onboard the NASA/ESA James Webb Space Telescope will be presented. The main design driver is the energy flow from the 35 K "hot" satellite interface to the 7 K "cold" MIRI interface. Carbon fibre reinforced plastic (CFRP...

  7. Study of a reinforced concrete beam strengthened using a combination of SMA wire and CFRP plate

    Science.gov (United States)

    Liu, Zhi-qiang; Li, Hui

    2006-03-01

    Traditional methods used for strengthening of reinforced concrete (RC) structures, such as bonding of steel plates, suffer from inherent disadvantages. In recent years, strengthening of RC structures using carbon fiber reinforced polymer (CFRP) plates has attracted considerable attentions around the world. Most existing research on CFRP plate bonding for flexural strengthening of RC beams has been carried out for the strength enhancement. However, little research is focused on effect of residual deformations on the strengthening. The residual deformations have an important effect on the strengthening by CFRP plates. There exists a very significant challenge how the residual deformations are reduced. Shape memory alloy (SMA) has showed outstanding functional properties as an actuator. It is a possibility that SMA can be used to reduce the residual deformation and make cracks of concrete close by imposing the recovery forces on the concrete in the tensile zone. It is only an emergency damage repair since the SMA wires need to be heated continuously. So, an innovative method of a RC beam strengthened by CFRP plates in combination with SMA wires was first investigated experimentally in this paper. In addition, the nonlinear finite element software of ABAQUS was employed to further simulate the behavior of RC beams strengthened through the new strengthening method. It can be found that this is an excellent and effective strengthening method.

  8. Tensile and fatigue behaviour of self-piercing rivets of CFRP to aluminium for automotive application

    Science.gov (United States)

    Kang, J.; Rao, H.; Zhang, R.; Avery, K.; Su, X.

    2016-07-01

    In this study, the tensile and fatigue behaviour of self-piercing rivets (SPRs) in carbon fibre reinforced plastic (CFRP) to aluminium 6111 T82 alloys were evaluated. An average maximum lap-shear tensile load capacity of 3858 N was achieved, which is comparable to metal-to-metal SPR lap-shear joints. The CFRP-Al SPRs failed in lap-shear tension due to pull-out of the rivet head from the CFRP upper sheet. The CFRP-Al SPR lap- shear specimens exhibited superior fatigue life compared to previously studied aluminium-to- aluminium SPR lap-shear joints. The SPR lap-shear joints under fatigue loads failed predominantly due to kinked crack growth along the width of the bottom aluminium sheet. The fatigue cracks initiated in the plastically deformed region of the aluminium sheet close to the rivet shank in the rivet-sheet interlock region. Scatter in fatigue life and failure modes was observed in SPR lap-shear specimens tested close to maximum tensile load.

  9. Effect of Thermal Distress on Residual Behavior of CFRP-Strengthened Steel Beams Including Periodic Unbonded Zones

    Directory of Open Access Journals (Sweden)

    Isamu Yoshitake

    2015-11-01

    Full Text Available This paper presents the residual behavior of wide-flange steel beams strengthened with high-modulus carbon fiber-reinforced polymer (CFRP laminates subjected to thermal loading. Because the coefficients of thermal expansion of the steel and the CFRP are different, temperature-induced distress may take place along their interface. Periodic unbonded zones are considered to represent local interfacial damage. Five test categories are designed depending on the size of the unbonded zones from 10 to 50 mm, and corresponding beams are loaded until failure occurs after exposing to a cyclic temperature range of ΔT = 25 °C (−10 to 15 °C up to 84 days. The composite action between the CFRP and the steel substrate is preserved until yielding of the beams happens, regardless of the thermal cycling and periodic unbonded zones. The initiation and progression of CFRP debonding become apparent as the beams are further loaded, particularly at geometric discontinuities in the vicinity of the unbonded zones along the interface. A simple analytical model is employed to predict the interfacial stress of the strengthened beams. A threshold temperature difference of ΔT = 30 °C is estimated for the initiation and progression of CFRP debonding. Multiple debonding-progression stages in conjunction with the extent of thermal distress appear to exist. It is recommended that high-modulus CFRP be restrictively used for strengthening steel members potentially exposed to a wide temperature variation range.

  10. Detection of Fiber Layer-Up Lamination Order of CFRP Composite Using Thermal-Wave Radar Imaging

    Science.gov (United States)

    Wang, Fei; Liu, Junyan; Liu, Yang; Wang, Yang; Gong, Jinlong

    2016-09-01

    In this paper, thermal-wave radar imaging (TWRI) is used as a nondestructive inspection method to evaluate carbon-fiber-reinforced-polymer (CFRP) composite. An inverse methodology that combines TWRI with numerical optimization technique is proposed to determine the fiber layer-up lamination sequences of anisotropic CFRP composite. A 7-layer CFRP laminate [0°/45°/90°/0°]_{{s}} is heated by a chirp-modulated Gaussian laser beam, and then finite element method (FEM) is employed to calculate the temperature field of CFRP laminates. The phase based on lock-in correlation between reference chirp signal and the thermal-wave signal is performed to obtain the phase image of TWRI, and the least square method is applied to reconstruct the cost function that minimizes the square of the difference between the phase of TWRI inspection and numerical calculation. A hybrid algorithm that combines the simulation annealing with Nelder-Mead simplex research method is employed to solve the reconstructed cost function and find the global optimal solution of the layer-up sequences of CFRP composite. The result shows the feasibility of estimating the fiber layer-up lamination sequences of CFRP composite with optimal discrete and constraint conditions.

  11. CFRP-Strengthening and Long-Term Performance of Fatigue Critical Welds of a Steel Box Girder

    Directory of Open Access Journals (Sweden)

    Roland E. Koller

    2014-02-01

    Full Text Available Empa’s research efforts in the 1990s provided evidence that a considerable increase of the fatigue strength of welded aluminum beams can be achieved by externally bonding pultruded carbon fiber reinforced polymer (CFRP laminates using rubber-toughened epoxies over the fatigue-weak welding zone on their tensile flange. The reinforcing effect obtained is determined by the stiffness of the unidirectional CFRP laminate which has twice the elastic modulus of aluminum. One can therefore easily follow that an unstressed CFRP laminate reinforcement of welded beams made of steel will not lead to a substantial increase in fatigue strength of the steel structure. This consideration led to the idea of prestressing an external reinforcement of the welded zone. The present investigation describes experimental studies to identify the adhesive system suitable for achieving high creep and fatigue strength of the prestressed CFRP patch. Experimental results (Wöhler-fields of shear-lap-specimens and welded steel beams reinforced with prestressed CFRP laminates are presented. The paper concludes by presenting a field application, the reinforcement of a steel pendulum by adhesively bonded prestressed CFRP laminates to the tensile flanges of the welded box girder. Inspections carried out periodically on this structure revealed neither prestress losses nor crack initiation after nine years of service.

  12. LATERAL HEAT FLOW INFRARED THERMOGRAPHY FOR THICKNESS INDEPENDENT DETERMINATION OF THERMAL DIFFUSIVITY IN CFRP

    International Nuclear Information System (INIS)

    In conventional infrared thermography, determination of thermal diffusivity requires thickness information. Recently GE has been experimenting with the use of lateral heat flow to determine thermal diffusivity without thickness information. This work builds on previous work at NASA Langley and Wayne State University but we incorporate thermal time of flight (tof) analysis rather than curve fitting to obtain quantitative information. We have developed appropriate theoretical models and a tof based data analysis framework to experimentally determine all components of thermal diffusivity from the time-temperature measurements. Initial validation was carried out using finite difference simulations. Experimental validation was done using anisotropic carbon fiber reinforced polymer (CFRP) composites. We found that in the CFRP samples used, the in-plane component of diffusivity is about eight times larger than the through-thickness component

  13. Experimental and Theoretical Analysis of Hollow Steel Columns Strengthening by CFRP

    Directory of Open Access Journals (Sweden)

    Keykha A.H.

    2015-09-01

    Full Text Available The need for strengthening and retrofitting is well known and extensive research is progressing in this field. The reasons for strengthening and retrofitting are numerous: increased loads, changes in use, deterioration, and so on. In recent years, the use of carbon fiber reinforced polymer (CFRP for strengthening has shown to be a competitive method, both regarding structural performance, and economical aspects. Extensive research has been carried out in this field. However, most of the research has been undertaken on concrete structures and for confinement, flexural, and shear strengthening. Limited research has been carried out on steel structures strengthened with CFRP. This paper presents axially loaded steel columns strengthened for increased load. The topic is studied theoretically and through laboratory tests. The theory covers analytical methods. Carbon fiber reinforced polymers has been used to strengthen the columns. The tests have been undertaken on full scale specimens, non-strengthened for reference, partially strengthened and fully strengthened

  14. Intermediate Crack Induced Debonding in Concrete Beams Strengthened with CFRP Plates - An Experimental Study

    DEFF Research Database (Denmark)

    Rusinowski, Piotr Michal; Täljsten, Björn

    2009-01-01

    FRP composites are becoming a material of choice in an increasing number of rehabilitation and retrofitting projects around the world. Depending on the design objectives, these materials can be used to improve one or more of the structural member characteristics, such as the load capacity...... strengthening method. End-peeling has governed a large interest and several debonding models have been presented. However, interfacial peeling at flexural cracks has not attained the same focus – even though this debonding failure is most likely more common. This paper presents laboratory tests of concrete...... beams strengthened in flexure with CFRP epoxy bonded plates. Wrapping with CFRP sheets was applied in order to try to localize the failure initiation. Concrete cracking as well as debonding initiation and propagation was possible to observe with help of advanced optical measuring system and high speed...

  15. Failure Load Test of a CFRP Strengthened Railway Bridge in Oumlrnskoumlldsvik, Sweden

    DEFF Research Database (Denmark)

    Täljsten, Björn; Bergström, Markus; Carolin, Anders

    2009-01-01

    using carbon fiber reinforced polymer (CFRP) rectangular rods epoxy bonded in sawed up slots, e.g., near surface mounted reinforcement. The strengthening was very successful and resulted in a desired shear failure when the bridge was loaded to failure. The load-carrying capacity in bending for the...... steel reinforcement by approximately 10%, and increased the height of the compressed zone by 100 mm. When the shear failure occurred, the utilization of the compression concrete and CFRP rods were 100 and 87.5%, respectively. This indicates that a bending failure indeed was about to occur, even though......The results obtained when performing a load test to failure of an existing structure are valuable when assessing calculation models, updating finite element models, and investigating the true structural behavior. In this paper a destructive testing and monitoring of a railway bridge in Örnsköldsvik...

  16. Study on Evaluating Damage of CFRP Using the PVDF Comb Transducer

    International Nuclear Information System (INIS)

    Recently, fiber reinforced plastic (FRP) materials become to be used more in producing airplanes because of high specific strength and low weight. However, there can be delamination caused from unexpected impact during the service flight. Since strength reduce comes with these delamination defects, defects in the composite materials should be monitored for safety of the airplane. A PVDF transducer can be used for on-line health monitoring economically. In this study, comb type of PVDF transducer was fabricated for generating and receiving of the guided wave at specific wavelength and was applied to evaluate natural delamination defect with the guided wave. Natural delamination in CFRP was produced with free dropping weight on CFRP surface between the transmitter and the receiver transducers. At every impacts, guided wave was generated and received in the pitch-catch way with the PVDF(Polyvinylidene fluoride) comb transducer and variation of the guided wave signal was compared according to accumulation of impact damage.

  17. Flat slabs strengthened to punching with carbon fiber reinforced polymer (CFRP dowels

    Directory of Open Access Journals (Sweden)

    Helder Luiz da Silva Rodrigues

    2015-10-01

    Full Text Available This paper presents results of punching tests carried out in four reinforced concrete flat slabs, one of them without shear reinforcement and others strengthened with CFRP dowels. Slabs were 1000 mm square meters and 60 mm thick and were subjected to mid span loadings until failure. The strengthening arrangements were radial and cruciform, varying the number of layers of CFRP dowels. The results presented include vertical displacements, strain on steel and concrete, ultimate loads and failure mode, as well as estimation of resistance based on the Brazilian standards. It was observed significant improvement on punching resistance of the strengthened slabs when compared to the reference slab, highlighting the good performance for the strengthening system evaluated.

  18. Effects of the shock duration on the response of CFRP composite laminates

    International Nuclear Information System (INIS)

    Shock loads induce a local tensile stress within a sample. The location and amplitude of this high strain rate stress can be monitored respectively by the duration and intensity of the shock. The process is applied to carbon fibre reinforced polymer (CFRP) composites, involved in aeronautic or defense industry. This paper describes the response of CFRP laminates of different thicknesses to a shock load normal to the fibres direction. The effects of the shock duration on the wave propagation are key issues of this work. Experiments have been performed on high power laser facilities and on a high power pulsed generator to get a wide range of pulse duration from fs to µs. Numerical simulation provides a comprehensive approach of the wave propagation and tensile stress generation within these complex materials. The main result concerns the relation between the load duration, the tensile stress and the induced delamination within 1, 4 and 8 ply composite laminates. (paper)

  19. Experimental investigation on CFRP milling by low power Q-switched Yb:YAG laser source

    Science.gov (United States)

    Genna, S.; Tagliaferri, F.; Papa, I.; Leone, C.; Palumbo, B.

    2016-05-01

    In the present study, laser milling of CFRP plate by means of a 30W Q-Switched Yb:YAG fiber laser is investigated through statistical analysis. Milling tests were performed at the nominal power changing the pulse power; the scanning speed, the hatch distance and the released energy. Design of Experiments (DoE) and ANalysis Of VAriance (ANOVA) were applied with the aim to improve the process performances in term of material removal rate and heat affected zone extension. The results show that, the adopted laser is an effective solution for the CFRP milling. Moreover, adopting an accurate approach to the problem, process variability and material damages can be easily reduced.

  20. High-power picosecond laser drilling/machining of carbon fibre-reinforced polymer (CFRP) composites

    Science.gov (United States)

    Salama, A.; Li, L.; Mativenga, P.; Sabli, A.

    2016-02-01

    The large differences in physical and thermal properties of the carbon fibre-reinforced polymer (CFRP) composite constituents make laser machining of this material challenging. An extended heat-affected zone (HAZ) often occurs. The availability of ultrashort laser pulse sources such as picosecond lasers makes it possible to improve the laser machining quality of these materials. This paper reports an investigation on the drilling and machining of CFRP composites using a state-of-the-art 400 W picosecond laser system. Small HAZs (drilled on sample of 6 mm thickness, whereas no HAZ was seen below the top surface on the cut surfaces. Multiple ring material removal strategy was used. Furthermore, the effect of laser processing parameters such as laser power, scanning speed and repetition rate on HAZ sizes and ablation depth was investigated.

  1. Inclusion of CFRP-Epoxy Composite for End Anchorage in NSM-Epoxy Strengthened Beams

    Directory of Open Access Journals (Sweden)

    Md. Akter Hosen

    2015-01-01

    Full Text Available Nowadays, the use of near surface mounted (NSM technique strengthening reinforced concrete (RC structural members is going very popular. The failure modes of NSM strengthened reinforced concrete (RC beams have been shown to be largely due to premature failure such as concrete cover separation. In this study, CFRP U-wrap end anchorage with CFRP fabrics was used to eliminate the concrete cover separation failure. A total of eight RC rectangular beam specimens of 125 mm width, 250 mm depth, and 2300 mm length were tested. One specimen was kept unstrengthened as a reference; three specimens were strengthened with NSM steel bars and the remaining four specimens were strengthened with NSM steel bars together with the U-wrap end anchorage. The experimental results showed that wrapped strengthened beams had higher flexural strength and superior ductility performance. The results also show that these beams had less deflection, strain, crack width, and spacing.

  2. Finite element analysis of hypervelocity impact behaviour of CFRP-Al/HC sandwich panel

    Directory of Open Access Journals (Sweden)

    Phadnis Vaibhav A.

    2015-01-01

    Full Text Available The mechanical response of CFRP-Al/HC (carbon fibre-reinforced/epoxy composite face sheets with Al honeycomb core sandwich panels to hyper-velocity impact (up to 1 km/s is studied using a finite-element model developed in ABAQUS/Explicit. The intraply damage of CFRP face sheets is analysed by mean of a user-defined material model (VUMAT employing a combination of Hashin and Puck criteria, delamination modelled using cohesive-zone elements. The damaged Al/HC core is assessed on the basis of a Johnson Cook dynamic failure model while its hydrodynamic response is captured using the Mie-Gruneisen equation of state. The results obtained with the developed finite-element model showed a reasonable correlation to experimental damage patterns. The surface peeling of both face sheets was evident, with a significant delamination around the impact location accompanied by crushing HC core.

  3. X-ray radiography and tomography study of delamination in a CFRP and honeycomb structures

    Czech Academy of Sciences Publication Activity Database

    Vavřík, D.; Jakůbek, J.; Jandejsek, I.; Kumpová, Ivana; Žemlička, J.

    Aachen: Shaker, 2014 - (Kastner, J.), s. 63-66 ISBN 978-3-8440-2557-6. [Conference on Industrial Computed Tomography ( ICT ). Wels (AT), 25.02.2014-28.02.2014] Grant ostatní: Evropská komise(XE) QUICOM Source of funding: R - rámcový projekt EK Keywords : X-ray imaging * delamination * CFRP * honyecomb Subject RIV: AL - Art, Architecture, Cultural Heritage

  4. Inter-laminar shear stress in hybrid CFRP/austenitic steel

    OpenAIRE

    Lopes, J.(Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil); Freitas, M; D. Stefaniak; Camanho, P.P.

    2015-01-01

    Bolted joints are the most common solution for joining composite components in aerospace structures. Critical structures such as wing to fuselage joints, or flight control surface fittings use bolted joining techniques. Recent research concluded that higher bearing strengths in composite bolted joints can be achieved by a CFRP/ Titanium hybrid lay-up in the vicinity of the bolted joint. The high costs of titanium motivate a similar research with the more cost competitive austeniti...

  5. Bond strength of short lap splices in RC beams confined with steel stirrups or external CFRP

    OpenAIRE

    Garcia, R.; Helal, Y.; Pilakoutas, K.; GUADAGNINI, M

    2015-01-01

    This paper investigates the bond behaviour of lapped steel bars using fifteen RC beams tested in flexure. Twelve of the beams were designed to fail by bond splitting at midspan, where the main flexural reinforcement was lapped 10 bar diameters. The parameters studied include the amount and type of confinement at midspan (no confinement, internal steel stirrups or externally bonded carbon FRP), concrete cover and bar size. The results show that the CFRP confinement enhanced the bond strength o...

  6. Evaluation of Seismic Behaviors of Partially Deteriorated Reinforced Concrete Circular Columns Retrofitted with CFRP

    OpenAIRE

    Dongxu Hou; Jianyun Pan; Xinglang Fan; Zhimin Wu; Prosper Marindiko

    2014-01-01

    Deficiency of the concrete strength in some regions of reinforced concrete (RC) columns in practice may weaken the seismic behaviors of columns. Its effects on RC columns should be well understood. This paper aims to investigate the influences of deteriorated segment on the seismic behaviors of partially deteriorated RC columns and attempts to recover the seismic behaviors of partially deteriorated columns with Carbon Fiber Reinforced Polymer (CFRP) composites. A finite element analysis was c...

  7. Analysis of Environmental and Operational Condition Effects on Guided Ultrasonic Waves in Stiffened CFRP Structures

    OpenAIRE

    Eckstein, Benjamin; Moix-Bonet, Maria; Bach, Martin

    2014-01-01

    Structural Health Monitoring by Guided Ultrasonic Waves for real world applications relies on compensation of operational and environmental effects. The effects to be taken into account are depending not only on the present factors for a particular application scenario, but as well on the structure to be monitored itself. Especially for stiffened CFRP structures, wave propagation and subsequent temperature effects are of increasing complex nature. The load and temperature condition of aerospa...

  8. Experimental behaviour of RC beams shear strengthened with NSM CFRP laminates

    OpenAIRE

    Dias, Salvador J. E.; Barros, Joaquim A. O.

    2011-01-01

    The near-surface mounted (NSM) is one of the most recent techniques applied for the increase of the shear resistance of reinforced concrete (RC) beams. This technique involves the installation of carbon fibre reinforcement polymers (CFRP) laminates into thin slits open on the concrete cover of the elements to strengthen. The effectiveness of this technique for the shear strengthening of T crosssection RC beams was assessed by experimental research. For this purpose, three inclination...

  9. Evaluation of the performance of full-scale RC beams prestressed with NSM-CFRP laminates

    OpenAIRE

    Costa, Inês; M. Rezazadeh; Barros, Joaquim A. O.

    2014-01-01

    Carbon Fibre Reinforced Polymers (CFRP) applied according to the Near Surface Mounted (NSM) technique are known as capable of increasing the ultimate flexural resistance of Reinforced Concrete (RC) elements, but for Serviceability Limit States (SLS) the load increment it provides is, in general, relatively limited. Recently, researchers are giving attention towards the possibility of applying prestressed NSM-CFRPs to increase significantly the load carrying capacity of RC elements at SLS. As ...

  10. Bond and flexural behavior of concrete elements strengthened with NSM CFRP laminate strips under fatigue loading

    OpenAIRE

    Fernandes, Pedro Miguel Gomes; Silva, Patrícia; Sena-Cruz, José

    2015-01-01

    This paper presents the results of an experimental research on bond and flexural behavior of concrete elements strengthened with carbon fiber reinforced polymer (CFRP) laminate strips under fatigue loading conditions, applied according to the near-surface mounted (NSM) strengthening technique. Long-term performance of the NSM system could be compromised by fatigue loading, which may result in deterioration and weakening of individual components (steel, FRP, concrete), or loss of b...

  11. Assessing the efficiency of CFRP discrete confinement systems for concrete column elements

    OpenAIRE

    Barros, Joaquim A. O.; Ferreira, Débora R. S. M.

    2008-01-01

    Concrete columns requiring strengthening intervention always contain a certain percentage of steel hoops. Applying strips of wet lay-up carbon fiber reinforced polymer (CFRP) sheets in-between the existent steel hoops might, therefore, be an appropriate confinement technique with both technical and economic advantages, when full wrapping of a concrete column is taken as a basis of comparison. To assess the effectiveness of this discrete confinement strategy, circular cross section...

  12. Assessing the efficiency of CFRP discrete confinement systems for concrete cylinders

    OpenAIRE

    Barros, Joaquim; Ferreira, Débora

    2008-01-01

    Concrete columns requiring strengthening intervention always contain a certain percentage of steel hoops. Applying strips of wet lay-up carbon fiber reinforced polymer (CFRP) sheets in-between the existent steel hoops might, therefore, be an appropriate confinement technique with both technical and economic advantages, when full wrapping of a concrete column is taken as a basis of comparison. To assess the effectiveness of this discrete confinement strategy, circular cross section concrete el...

  13. ADHESIVE WEAR PERFORMANCE OF CFRP MULTILAYERED POLYESTER COMPOSITES UNDER DRY/WET CONTACT CONDITIONS

    OpenAIRE

    D. DANAELAN; B. F. YOUSIF

    2008-01-01

    The tribo-performance of a new engineering composite material based on coconut fibers was investigated. In this work, coconut fibers reinforced polyester (CFRP) composites were developed. The tribo-experiments were conducted by using pin-on-disc machine under dry and wet sliding contact condition against smooth stainless steel counterface. Worn surfaces were observed using optical microscope. Friction coefficient and specific wear rate were presented as a function of sliding distance (0–0.6 k...

  14. Quantitative impact characterization of aeronautical CFRP materials with non-destructive testing methods

    Energy Technology Data Exchange (ETDEWEB)

    Kiefel, Denis, E-mail: Denis.Kiefel@airbus.com, E-mail: Rainer.Stoessel@airbus.com; Stoessel, Rainer, E-mail: Denis.Kiefel@airbus.com, E-mail: Rainer.Stoessel@airbus.com [Airbus Group Innovations, Munich (Germany); Grosse, Christian, E-mail: Grosse@tum.de [Technical University Munich (Germany)

    2015-03-31

    In recent years, an increasing number of safety-relevant structures are designed and manufactured from carbon fiber reinforced polymers (CFRP) in order to reduce weight of airplanes by taking the advantage of their specific strength into account. Non-destructive testing (NDT) methods for quantitative defect analysis of damages are liquid- or air-coupled ultrasonic testing (UT), phased array ultrasonic techniques, and active thermography (IR). The advantage of these testing methods is the applicability on large areas. However, their quantitative information is often limited on impact localization and size. In addition to these techniques, Airbus Group Innovations operates a micro x-ray computed tomography (μ-XCT) system, which was developed for CFRP characterization. It is an open system which allows different kinds of acquisition, reconstruction, and data evaluation. One main advantage of this μ-XCT system is its high resolution with 3-dimensional analysis and visualization opportunities, which enables to gain important quantitative information for composite part design and stress analysis. Within this study, different NDT methods will be compared at CFRP samples with specified artificial impact damages. The results can be used to select the most suitable NDT-method for specific application cases. Furthermore, novel evaluation and visualization methods for impact analyzes are developed and will be presented.

  15. Experimental Investigation of CFRP Confined Columns Damaged by Alkali Aggregate Reaction

    Directory of Open Access Journals (Sweden)

    Siti Radziah Abdullah

    2012-10-01

    Full Text Available Fiber reinforced polymer is the most effective repair material in use to enhance the strength and ductility of deteriorated reinforced concrete columns. Often, fiber reinforced polymer (FRP provides passive confinement to columns until the dilation and cracking of concrete occurs. In the case of concrete suspected of Alkali Aggregate Reaction (AAR where concrete undergoes expansion, FRP wrap provides active confinement to the expanded concrete. In this study, the performance of carbon fiber reinforced polymer (CFRP wrapped columns damaged by AAR is evaluated based on the number of FRP layers and the time of the polymer application which provides two types of confinement: active or passive. The columns were tested under axial compression to evaluate the residual strength of the columns in comparison with unwrapped columns. The results reveal that the strength of the wrapped columns is enhanced with an increase in the number of CFRP layers. The strength of the columns under passive confinement is higher than the columns under active confinement. Under active confinement, early CFRP wrapping leads to improvement in the strength of the columns.

  16. Cost-reduction method for delamination monitoring using electrical resistance changes of CFRP beam

    Science.gov (United States)

    Todoroki, A.; Ueda, M.

    2004-02-01

    Delamination is a significant defect of laminated composites. The present study employs an electrical resistance change method in an attempt to identify internal delaminations experimentally. The method adopts reinforcing carbon fibers as sensors. In our previous paper, an actual delamination crack in a Carbon Fiber Reinforced Plastics (CFRP) laminate was experimentally identified with artificial neural networks (ANN) or response surfaces created from a large number of experiments. The experimental results were used for learning of the ANN or regression of the response surfaces. For the actual application of the method, it is indispensable to reduce the number of experiments to suppress the total experimental cost. In the present study, therefore, FEM analyses are employed to make sets of data for learning of the ANN. First, electrical conductivity of the CFRP laminate is identified by means of the least estimation error method. After that, the results of FEM analyses are used for learning of the ANN. The method is applied to actual delamination monitoring of CFRP beams. As a result, the method successfully monitored the delamination location and size only with ten experiments.

  17. Development of active CFRP/metal laminates and their demonstrations in complicated forms

    Science.gov (United States)

    Asanuma, H.; Nakata, T.; Tanaka, T.; Imori, M.; Haga, O.

    2006-03-01

    This paper describes development of high performance CFRP/metal active laminates and demonstrations of them in complicated forms. Various types of the laminates were made by hot-pressing of an aluminum, aluminum alloys, a stainless steel and a titanium for the metal layer as a high CTE material, a unidirectional CFRP prepreg as a low CTE/electric resistance heating material, a unidirectional KFRP prepreg as a low CTE/insulating material. The aluminum and its alloy type laminates have almost the same and the highest room temperature curvatures and they linearly change with increasing temperature up to their fabrication temperature. The curvature of the stainless steel type jumps from one to another around its fabrication temperature, whereas the titanium type causes a double curvature and its change becomes complicated. The output force of the stainless steel type attains the highest of the three under the same thickness. The aluminum type successfully increased its output force by increasing its thickness and using its alloys. The electric resistance of the CFRP layer can be used to monitor the temperature, that is, the curvature of the active laminate because the curvature is a function of temperature. The aluminum type active laminate was made into complicated forms, that is, a hatch, a stack, a coil and a lift types, and their actuation performances were successfully demonstrated.

  18. Diagnostic possibilities following implantation of carbon-fibre-reinforced plastic (CFRP) total hip arthroplasty

    International Nuclear Information System (INIS)

    Introduction: There are many problems in the radiological diagnosis of aseptic loosening in total hip arthroplasty. Computed tomography (CT) and magnetic resonance tomography (MRT) are not usable for metallic implants (stainless steel, cobalt alloy, titanium alloy). Material and Methods: From April 1993 to December 1993 15 CFRP non-cemented hip prostheses have been implanted. In a prospective clinical study plane radiographs, CT and MRT have been analysed. Results: Three stems were revised (1 femoral fracture, 1 severe thigh pain, 1 aseptic loosening). CFRP are not visible in plane radiographs. There was a complete (two-third of the cases) or nearly complete (one-third of the cases) small sclerotic interface between the prosthesis and the bone, these were apparent in CT and MRT in stable implant cases and did not have any clinical correlations. Discussion: The small sclerotic interface is quite different in comparison to so called 'Reactive lines'. In one case of aseptic loosening there was an interposition of soft tissue between prothesis and bone in MRT and CT. CFRP inaugurates new diagnostic possibilities in aseptic loosening of hip prosthesis and in tumour surgery too. (orig.)

  19. Quantitative impact characterization of aeronautical CFRP materials with non-destructive testing methods

    Science.gov (United States)

    Kiefel, Denis; Stoessel, Rainer; Grosse, Christian

    2015-03-01

    In recent years, an increasing number of safety-relevant structures are designed and manufactured from carbon fiber reinforced polymers (CFRP) in order to reduce weight of airplanes by taking the advantage of their specific strength into account. Non-destructive testing (NDT) methods for quantitative defect analysis of damages are liquid- or air-coupled ultrasonic testing (UT), phased array ultrasonic techniques, and active thermography (IR). The advantage of these testing methods is the applicability on large areas. However, their quantitative information is often limited on impact localization and size. In addition to these techniques, Airbus Group Innovations operates a micro x-ray computed tomography (μ-XCT) system, which was developed for CFRP characterization. It is an open system which allows different kinds of acquisition, reconstruction, and data evaluation. One main advantage of this μ-XCT system is its high resolution with 3-dimensional analysis and visualization opportunities, which enables to gain important quantitative information for composite part design and stress analysis. Within this study, different NDT methods will be compared at CFRP samples with specified artificial impact damages. The results can be used to select the most suitable NDT-method for specific application cases. Furthermore, novel evaluation and visualization methods for impact analyzes are developed and will be presented.

  20. Acoustic Emission Monitoring of Lightning-Damaged CFRP Laminates during Compression-after-Impact Test

    International Nuclear Information System (INIS)

    Carbon-fiber reinforced plastic(CFRP) laminates made of nano-particle-coated carbon fibers and damaged by a simulated lightning strike were tested under compression-after-impact(CAI) mode, during which the damage progress due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. Conductive nano-particles were coated directly on the fibers, from which CFRP coupons were made. The coupon were subjected to the strikes with a high voltage/current impulse of 10-40 kA within a few . The effects of nano-particle coating and the degree of damage induced by the simulated lightning strikes on AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terms of damage area by using ultrasonic C-scan images. The assessment during the CAI tests of damaged CFRP showed that AE monitoring appeared to be useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes.

  1. Quantitative impact characterization of aeronautical CFRP materials with non-destructive testing methods

    International Nuclear Information System (INIS)

    In recent years, an increasing number of safety-relevant structures are designed and manufactured from carbon fiber reinforced polymers (CFRP) in order to reduce weight of airplanes by taking the advantage of their specific strength into account. Non-destructive testing (NDT) methods for quantitative defect analysis of damages are liquid- or air-coupled ultrasonic testing (UT), phased array ultrasonic techniques, and active thermography (IR). The advantage of these testing methods is the applicability on large areas. However, their quantitative information is often limited on impact localization and size. In addition to these techniques, Airbus Group Innovations operates a micro x-ray computed tomography (μ-XCT) system, which was developed for CFRP characterization. It is an open system which allows different kinds of acquisition, reconstruction, and data evaluation. One main advantage of this μ-XCT system is its high resolution with 3-dimensional analysis and visualization opportunities, which enables to gain important quantitative information for composite part design and stress analysis. Within this study, different NDT methods will be compared at CFRP samples with specified artificial impact damages. The results can be used to select the most suitable NDT-method for specific application cases. Furthermore, novel evaluation and visualization methods for impact analyzes are developed and will be presented

  2. Shear response and design of RC beams strengthened using CFRP laminates

    Science.gov (United States)

    Singh, Shamsher B.

    2013-12-01

    The present investigation addresses the shear strengthening of deficient reinforced concrete (RC) beams using carbon fiber-reinforced polymer (CFRP) sheets. The effect of the pattern and orientation of the strengthening fabric on the shear capacity of the strengthened beams were examined. Three beams with various lay-ups of strengthening fabric, 45°, 0°/90°, and 0°/90°/45° were examined, in addition to an unstrengthened control beam. Principal and shear strains were measured at different locations at the critical sections of the strengthened beams corresponding to each applied shear force. Experimental results showing the advantage of beam strengthened using the various lay-ups of CFRP sheets are discussed. It is concluded that Beam-45°, Beam-0°/90°, and Beam-0°/90°/45° show about 25%, 19%, and 40% increases in shear-load carrying capacity in comparison to the control beam, respectively. Also, there exists a critical value of shear force up to which there is no appreciable shear strain in the CFRP sheets/beam. This shear force marks the ultimate shear resistance of the control beam. However, the strengthened beams exhibited significant strength and stiffness even beyond the critical value of the shear force. A design example for shear strengthening shows that the design equations available in the literature underestimate the actual shear strength of the beams.

  3. Experimental and Numerical Research on Seismic Performance of Earthquake-Damaged RC Frame Strengthened with CFRP Sheets

    Directory of Open Access Journals (Sweden)

    Lai Wang

    2016-01-01

    Full Text Available In order to assess the seismic performance of damaged reinforced concrete (RC frame strengthened with carbon fiber reinforced polymers (CFRP sheets, two experimental specimens with identical reinforcement ratio and geometric dimensions were designed following Chinese code for seismic design of buildings. Experimental specimens consist of a reference (undamaged RC frame, namely, KJ-1, and an earthquake-damaged RC frame strengthened with CFRP sheets, namely, KJ-2. A pseudostatic test was conducted on the two specimens to simulate moderate earthquake damage. The strengthening effects of CFRP sheets on damaged RC frame were discussed in terms of hysteretic curve, skeleton curve, stiffness degradation, and ductility. In addition, numerical method based on fiber model method was utilized to analyze the seismic performance of KJ-1 and KJ-2 and it is compared with the experimental result. Both the results confirm that the method of exterior bonding CFRP sheets on the damaged RC frame has restored the seismic performance such as bearing capacity, stiffness, and ductility to its original undamaged level, and some of the seismic performance of the damaged RC frame strengthened with CFRP sheets is even better than the undamaged one, which proves that the method has significant effect in strengthening postearthquake-damaged RC frames.

  4. Time-variant flexural reliability of RC beams with externally bonded CFRP under combined fatigue-corrosion actions

    International Nuclear Information System (INIS)

    Time-variant reliability analysis of RC highway bridges strengthened with carbon fibre reinforced polymer CFRP laminates under four possible competing damage modes (concrete crushing, steel rupture after yielding, CFRP rupture and FRP plate debonding) and three degradation factors is analyzed in terms of reliability index β using FORM. The first degradation factor is chloride-attack corrosion which induces reduction in steel area and concrete cover cracking at characteristic key times (corrosion initiation, severe surface cover cracking). The second degradation factor considered is fatigue which leads to damage in concrete and steel rebar. Interaction between corrosion and fatigue crack growth in steel reinforcing bars is implemented. The third degradation phenomenon is the CFRP properties deterioration due to aging. Considering these three degradation factors, the time-dependent flexural reliability profile of a typical simple 15 m-span intermediate girder of a RC highway bridge is constructed under various traffic volumes and under different corrosion environments. The bridge design options follow AASHTO-LRFD specifications. Results of the study have shown that the reliability is very sensitive to factors governing the corrosion. Concrete damage due to fatigue slightly affects reliability profile of non-strengthened section, while service life after strengthening is strongly related to fatigue damage in concrete. - Highlights: • We propose a method to follow the time-variant reliability of strengthened RC beams. • We consider multiple competing failure modes of CFRP strengthened RC beams. • We consider combined degradation mechanisms (corrosion, fatigue, ageing of CFRP)

  5. Fatigue damage evaluation of plain woven carbon fiber reinforced plastic (CFRP) modified with MFC (micro-fibrillated cellulose) by thermo-elastic damage analysis (TDA)

    Science.gov (United States)

    Aoyama, Ryohei; Okubo, Kazuya; Fujii, Toru

    2013-04-01

    The aim of this study is to investigate characteristics of fatigue damage of CFRP modified with MFC by TDA under tensile cyclic loading. In this paper, fatigue life of CFRP modified with MFC was investigated under cyclic loading. Characteristics of fatigue damage of CFRP modified with MFC were evaluated by thermo-elastic damage analysis. Maximum improvement in fatigue life was also obtained under cyclic loading when epoxy matrix was enhanced with 0.3wt% of MFC as well as under static loading. Result of TDA showed same tendency as the result of fatigue test, and the result of TDA well expressed the fatigue damage behavior of plain woven CFRP plate. Eventually, TDA was effective for clear understanding the degree of fatigue damage progression of CFRP modified with MFC.

  6. Stochastic finite element analysis of long-span bridges with CFRP cables under earthquake ground motion

    Indian Academy of Sciences (India)

    Özlem Çavdar; Alemdar Bayraktar; Süleyman Adanur; Hasan Basri Başaǧa

    2010-06-01

    Stochastic seismic analysis of long-span bridges with Carbon fibre reinforced polymer (CFRP) cables are presented in this study through combination of the advantages of the perturbation based stochastic finite element method (SFEM) and Monte Carlo simulation (MCS) method. Jindo cable-stayed and Fatih Sultan Mehmet (Second Bosporus) suspension bridges are chosen as an example. Carbon fibre reinforced polymer cable (CFRP) and steel cables are used separately, in which the cable’s cross sectional area is determined by the principle equivalent axial stiffness. Geometric nonlinear effects are considered in the analysis. Uncertainties in the material are taken into account and Kocaeli earthquake in 1999 is chosen as a ground motion. The efficiency and accuracy of the proposed algorithm are validated by comparing with results of MCS method. It can be stated that using of CFRP cables in long-span bridges subjected to earthquake forces is feasible.

  7. Thermal conductivity measurement below 40 K of the CFRP tubes for the Mid-Intrared Instrument mounting struts

    DEFF Research Database (Denmark)

    Shaughnessy, B. M.; Eccleston, P.; Fereday, K. J.;

    2007-01-01

    The Mid-Infrared Instrument (MIRI) is one of four instruments on the James Webb Space Telescope observatory, scheduled for launch in 2013. It must be cooled to about 7 K and is supported within the telescope’s 40 K instrument module by a hexapod of carbon fibre reinforced plastic (CFRP) tubing....... This article describes the measurement of cryogenic thermal conductivity of the candidate CFRP. Measured thermal conductivities were about 0.05 W/m K at a mean temperature of 10 K increasing to about 0.20 W/m K at a mean temperature of 40 K....

  8. A study on non-contact ultrasonic technique for on-line inspection of CFRP

    International Nuclear Information System (INIS)

    The advantages of carbon fiber reinforced plastic materials (CFRP) are: they are light structure materials, they have corrosion resistance, and higher specific strength and elasticity. The recently developed 3-dimentional fiber placement system is able to produce a more complex and various shaped structures due to less limitations of a product shape according to the problem in conventional fabrication process. This fiber placement system stacks the narrow prepreg tape on the mold according to the designed sequence and thickness. Non-destructive evaluation was rquired for these composites to evaluate changes in strength caused by defects such as delamination and porosity. Additionally, the expectent quality should be satisfied for the high cost fabrication process using the fiber placement system. Therefore, an on line non-destructive evaluation system is required and real-time complement is needed when the defects are detected [1]. Defect imaging by the ultrasonic C-scan method is a useful technique for defect detection in CFRP. However, the conventional ultrasonic C-scan technique cannot be applied during the fabrication process because the test piece should be immersed into the water. Therefore, non-contact ultrasonic techniques should be applied during the fabricating process. For the development of non-contact ultrasonic techniques available in non-destructive evaluation of CFRP, a recent laser-generated ultrasonic technique and an air-coupled transducer that transmit and receive ultrasounds in the air are studied [2-3]. In this study, generating and receiving techniques of laser-generated ultrasound and the characteristics of received signals upon the internal defects of CFRO were studied for non-contact inspection

  9. Confining concrete with sisal and jute FRP as alternatives for CFRP and GFRP

    Directory of Open Access Journals (Sweden)

    Tara Sen

    2015-12-01

    Full Text Available This research paper presents an experimental investigation on the confinement strength and confinement modulus of concrete cylinders confined using different types of natural fibre composites and a comparative performance analysis with different artificial fibre based composite materials. The paper also highlights the need to switch over from the utilization of artificial fibres, which are non-renewable and fossil fuel products, to environmental beneficial materials like green fibres. The utilization of plant products like sisal and jute fibres and their composites in various structural engineering applications addresses the issues of sustainability and renewability with constructional materials. The paper describes a suitable mechanical treatment method like high temperature conditioning, which aids us in further improving the properties of these woven natural materials like sisal and jute for composite fabrication and utilization. Heat treated natural fibres of woven sisal and jute were utilized for confining concrete cylinders similar to CFRP and GFRP confinement and their confinement characteristics were obtained and compared. All the cylinders were subjected to monotonic axial compressive loads, so as to evaluate the effect of confinement on the axial load carrying capacity and all their failure modes were discussed thoroughly. The results indicated superior performance by sisal FRP as well as jute FRP confined cylinders as compared to controlled or unconfined cylinders, also sisal FRP wrapped cylinders displayed ultimate axial load of comparable magnitude to CFRP confinement. Natural FRP confinement displayed superior confinement modulus and confinement strength, also the ultimate axial load of concrete cylinders confined with natural FRPs underwent 66% enhancement by sisal FRP and 48% enhancement by jute FRP, in comparison with controlled or unconfined cylinders. Enhancement in axial load carrying capacity was 83% with CFRP confinement

  10. Finite element simulation and testing of ISW CFRP anchorage

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Goltermann, Per; Hertz, Kristian Dahl

    2013-01-01

    modelled in the 3D finite Element program ABAQUS, just as digital image correlation (DIC) testing was performed to verify the finite element simulation. Also a new optimized design was produced to ensure that the finite element simulation and anchorage behaviour correlated well. It is seen that the...

  11. New Proposal for Flexural Strengthening of Reinforced Concrete Beams Using CFRP T-Shaped Profiles

    Directory of Open Access Journals (Sweden)

    Renata Kotynia

    2015-11-01

    Full Text Available The purpose of this study was to evaluate the performance of a novel strengthening system using T-shaped carbon fiber reinforced polymer (CFRP profiles. The proposed system successfully combines the advantages of two established strengthening techniques, namely the near surface mounted (NSM and externally bonded (EB methods. The paper presents the experimental results of structural tests carried out on seven flexurally-strengthened and two non-strengthened full-scale reinforced concrete (RC members. Two T-shaped profiles having heights of 15 and 30 mm were applied. The main parameters of concrete strength and composite strengthening ratio were investigated to evaluate the efficiency of the proposed flexural strengthening system. All specimens were tested under a quasi-static six-point bending configuration. The test results showed a significant increase in the load bearing capacity and the stiffness of the RC beams with strengthening and also a notable reduction in maximum deflections. The high tensile strength utilization of the CFRP profiles places this strengthening technique as a promising alternative to other, less structurally-efficient systems.

  12. Analysis of fracture surface of CFRP material by three-dimensional reconstruction methods

    International Nuclear Information System (INIS)

    Fracture surfaces of CFRP (carbon Fiber Reinforced Polymer) materials, used in the nuclear fuel cycle, presents an elevated roughness, mainly due to the fracture mode known as pulling out, that displays pieces of carbon fibers after debonding between fiber and matrix. The fractographic analysis, by bi-dimensional images is deficient for not considering the so important vertical resolution as much as the horizontal resolution. In this case, the knowledge of this heights distribution that occurs during the breaking, can lead to the calculation of the involved energies in the process that would allows a better agreement on the fracture mechanisms of the composite material. An important solution for the material characterization, whose surface presents a high roughness due to the variation in height, is to reconstruct three-dimensionally these fracture surfaces. In this work, the 3D reconstruction was done by two different methods: the variable focus reconstruction, through a stack of images obtained by optical microscopy (OM) and the parallax reconstruction, carried through with images acquired by scanning electron microscopy (SEM). The results of both methods present an elevation map of the reconstructed image that determine the height of the surface pixel by pixel,. The results obtained by the methods of reconstruction for the CFRP surfaces, have been compared with others materials such as aluminum and copper that present a ductile type fracture surface, with lower roughness. (author)

  13. Cost and Ductility Effectiveness of Concrete Columns Strengthened with CFRP and SFRP Sheets

    Directory of Open Access Journals (Sweden)

    Khaled Abdelrahman

    2014-05-01

    Full Text Available Recently, steel fibre reinforced polymers (SFRP sheets have been introduced for the repair and rehabilitation of concrete structures. Few researchers studied the behaviour of the concrete columns wrapped with SFRP sheets; however, several critical parameters such as the cost and ductility effectiveness of the SFRP wrapped concrete columns have been lightly addressed. Thus, the main objective of this paper is to study the cost and ductility effectiveness of SFRP wrapped concrete columns and compare the results with the conventionally used carbon FRP (CFRP wrapped concrete columns. In addition, an analytical procedure to predict the cost effectiveness of SFRP wrapped concrete columns is also suggested, from which, a parametric study was conducted. The parametric study investigated the effect of the concrete strength, the number of SFRP layers, and the size and slenderness effects on the cost effectiveness of the concrete columns wrapped with SFRP sheets. The results from the cost and ductility effectiveness study indicated that the SFRP wrapped concrete columns showed enhanced performance over the CFRP wrapped concrete columns. The suggested analytical procedure proved to be a reliable and accurate method to predict the cost effectiveness parameter of SFRP wrapped concrete columns. The parametric study showed the significant impact of the investigated parameters on the cost effectiveness of concrete columns wrapped with SFRP sheets.

  14. Study on electromechanical impedance characteristics of part of structures made of CFRP

    Science.gov (United States)

    Malinowski, Paweł H.; Wandowski, Tomasz; Ostachowicz, Wiesław M.

    2016-04-01

    Carbon Fibre Reinforced Polymers (CFRP) are more and more used in many branches of industry. Researchers are developing numerous techniques of non-destructive assessment of the structures made out of CFRP such as guided waves, ultrasonics, laser induced fluorescence and others. In this research we focus on electromechanical impedance (EMI) technique. In this technique a piezoelectric sensor is either surface mounted or embedded into investigated host structure. The electrical quantities of the sensor are measured for wide frequency range. Due to piezoelectric effect the electrical response of the sensor is related to mechanical response of the structure to which the sensors is bonded to. In the reported research impedance spectra in the vicinity of the transducer thickness mode were investigated as well as the lower frequency range. The spectra that were analysed were gathered from samples with surface treatment such as thermal degradation and samples adhesively bonded with film adhesive with symmetric and unsymmetric bond. Moreover, the samples with modified adhesive bonds were investigated. These spectra for different cases were compared with reference measurement results gathered from pristine samples. Numerical indexes for comparison of the EMI characteristics were proposed. The comparison of the indexes was also conducted. In the experimental part of the research the piezoelectric transducer was mounted at the sample surface. Measurements were conducted using HIOKI Impedance Analyzer IM3570.

  15. Scanning induction thermography (SIT) for imaging damages in carbon-fibre reinforced plastics (CFRP) components

    Science.gov (United States)

    Thomas, K. Renil; Balasubramaniam, Krishnan

    2015-03-01

    Scanning Induction Thermography (SIT) combines both Eddy Current Technique (ECT) and Thermographic Non-Destructive Techniques (TNDT) [1],[2]. This NDT technique has been earlier demonstrated for metallic components for the detection of cracks, corrosion, etc.[3]-[9] Even though Carbon-Fiber Reinforced Plastics (CFRP) has a relatively less electrical conductivity compared to metals, it was observed that sufficient heat could be generated using induction heating that can be used for nondestructive evaluation using the Induction Thermography technique. Also, measurable temperatures could be achieved using relatively less currents, when compared to metals. In Scanning Induction Thermography (SIT) technique, the induction coil moves over the sample at optimal speeds and the temperature developed in the sample due to Joule heating effects is captured as a function of time and distance using an IR camera in the form of video images. A new algorithm is also presented for the analysis of the video images for improved analysis of the data obtained. Several CFRP components were evaluated for detection of impact damage and delaminations using the SIT technique.

  16. Numerical Determination of Shear Strength of Steel Reinforced Concrete Column Strengthened by CFRP Sheets

    Institute of Scientific and Technical Information of China (English)

    王铁成; 余流; 王立军

    2003-01-01

    The earthquake-resistant property of reinforced concrete members depends on the interaction between reinforcing bars and surrounding concrete through bond to a large degree. In this paper a general system aimed at dealing with the failure analysis of reinforced concrete columns strengthened with carbon-fiber-reinforced plastic (CFRP) sheets including bond-slip of the anchored reinforcing bars at the foot of the columns is presented. It is based on the yield design theory with a mixed modeling of the structure, according to which the concrete material is treated as a classical two-dimensional continuum, whereas the longitudinal reinforcing bars are regarded as one-dimensional rods including bond-slip at the foot of the columns. In shear reinforced zones both the shear CFRP sheets and transverse reinforcing bars are incorporated in the analysis through a homogenization procedure and they are only in tension. The approach is then implemented numerically by means of the finite-element formulation. The numerical procedure produces accurate estimates for the loading-carrying capacity of the shear members taken as an illustrative application by correlation with the experimental results, so the proposed approach is valid.

  17. Three-dimensional measurement of CFRP deformation during high-speed impact loading

    International Nuclear Information System (INIS)

    The deformation of carbon fiber reinforced plastics (CFRPs) caused by projectile impact governs the absorption or dissipation of kinetic energy of the projectile. However, three-dimensional (3D) numerical information about the CFRP deformations caused by the projectile impact is not yet available. Therefore, a 3D measurement was conducted to evaluate the deformation process and deformation behavior of the CFRPs under high-velocity projectile impact, and to subsequently evaluate the performance of the CFRPs. CFRPs having two different stacking sequences were used as the specimens. For measuring the deformation, a high-speed stereovision system comprised of two high-speed video cameras was adopted. An SUJ-2 sphere projectile was impacted against a specimen plate using a light-gas accelerator at an impact velocity of approximately 175 m/s, and the deformation was recorded by synchronously capturing the images using this system. The captured images were converted to stereo images by a 3D correlation method. The stereo images clearly revealed numerical differences in the deformation of the CFRPs having different stacking sequences. The result accuracy of the 3D measurement was verified by comparing their results with the direct measurement results. Moreover, the stereo images corresponded to the results from a numerical simulation of the CFRP deformations, which both qualitatively and quantitatively confirms the validity of the simulation. This 3D measurement method is a powerful and useful tool for evaluating the performance of CFRPs during high-velocity projectile impact.

  18. Automated transient thermography for the inspection of CFRP structures: experimental results and developed procedures

    Science.gov (United States)

    Theodorakeas, P.; Avdelidis, N. P.; Hrissagis, K.; Ibarra-Castanedo, C.; Koui, M.; Maldague, X.

    2011-05-01

    In thermography surveys, the inspector uses the camera to acquire images from the examined part. Common problems are the lack of repeatability when trying to repeat the scanning process, the need to carry the equipment during scanning, and long setting-up time. The aim of this paper is to present transient thermography results on CFRP plates for assessing different types of fabricated defects (impact damage, inclusions for delaminations, etc), as well as and to discuss and present a prototype robotic scanner to apply non destructive testing (thermographic scanning) on materials and structures. Currently, the scanning process is not automatic. The equipment to be developed, will be able to perform thermal NDT scanning on structures, create the appropriate scanning conditions (material thermal excitation), and ensure precision and tracking of scanning process. A thermographic camera that will be used for the image acquisition of the non destructive inspection, will be installed on a x, y, z, linear manipulator's end effector and would be surrounded by excitation sources (optical lamps), required for the application of transient thermography. In this work various CFRP samples of different shape, thickness and geometry were investigated using two different thermographic systems in order to compare and evaluate their effectiveness concerning the internal defect detectability under different testing conditions.

  19. Evaluation of Fatigue Strength Improvement by CFRP Laminates and Shot Peening onto the Tension Flanges Joining Corrugated SteelWebs

    Directory of Open Access Journals (Sweden)

    Zhi-Yu Wang

    2015-08-01

    Full Text Available Corrugated steel web with inherent high out-of-plane stiffness has a promising application in configuring large span highway bridge girders. Due to the irregularity of the configuration details, the local stress concentration poses a major fatigue problem for the welded flange plates of high strength low alloy structural steels. In this work, the methods of applying CFRP laminate and shot peening onto the surfaces of the tension flanges were employed with the purpose of improving the fatigue strength of such configuration details. The effectiveness of this method in the improvement of fatigue strength has been examined experimentally. Test results show that the shot peening significantly increases hardness and roughness in contrast to these without treatment. Also, it has beneficial effects on the fatigue strength enhancement when compared against the test data of the joints with CFRP strengthening. The stiffness degradation during the loading progress is compared with each treatment. Incorporating the stress acting on the constituent parts of the CFRP laminates, a discussion is made regarding the mechanism of the retrofit and related influencing factors such as corrosion and economic cost. This work could enhance the understanding of the CFRP and shot peening in repairing such welded details and shed light on the reinforcement design of welded joints between corrugated steel webs and flange plates.

  20. Active deformation and engineering analysis of CFRP mirror of various lay-up sequences within quasi-isotropic laminates

    Science.gov (United States)

    Zeng, Chunmei; Yu, Xia; Guo, Peiji

    2014-08-01

    A regularization stiffness coefficient method was verified further to optimize lay-up sequences of quasi-isotropic laminates for carbon fiber reinforced polymer (CFRP) composite mirrors. Firstly, the deformation due to gravity of 1G and temperature difference of 20-100°C and the modal were analyzed by finite element method (FEM). Secondly, the influence of angle error of ply stacking on quasi-isotropic of bending stiffness was evaluated. Finally, an active support system of 49 actuators in circular arrangement is designed for a 500mm CFRP mirror, and its goal is to deform the spherical CFRP mirror to a parabolic. Therefore, the response functions of the actuators were gotten, and the surface form errors and stresses were calculated and analyzed. The results show that the CFRP mirrors designed by the method have a better symmetrical bending deformation under gravity and thermal load and a higher fundamental frequency, and the larger n the better symmetry (for π/n quasi-isotropic laminates); the method reduces the sensitivity to misalignment of ply orientation for symmetric bending, and the mirror's maximum von Mises stress and maximum shear stress are less compared to those laminates not optimized in lay-up sequence.

  1. Experimental Investigation on Shear Resistance Behaviour of RC Precracked and Non-Precracked T-Beams using Discrete CFRP Strips

    Directory of Open Access Journals (Sweden)

    J. Jayaprakash

    2009-12-01

    Full Text Available The exploitation of Fibre Reinforced Polymer (FRP composites as external reinforcement is an evergreen technique for improving the structural performance of the existing Reinforced Concrete (RC structures. This paper presents a experimental investigation on shear strengthening capacity and modes of failure of precracked and non-precracked RC beams bonded externally with bi-directional Carbon Fibre Reinforced Polymer (CFRP fabric strips. Twelve RC T- beams were fabricated with different internal longitudinal and shear reinforcements. These beams were subjected to two types of loading; namely three point and four point bending systems. The beams were classified into three categories namely control, precracked-repaired, and initially strengthened (i.e. non-precracked beams. Prior to the application of CFRP shear reinforcement, the precracked-repaired beams were partially loaded to develop shear cracks along the shear spans, whereas the initially strengthened beams were strengthened with CFRP reinforcement without the application of any preloading. The overall increase in shear enhancement of the precracked-repaired and initially strengthened beams ranged between 13% and 61% greater over their control beams. It was found that the application of CFRP strips in the precracked-repaired beams attained better performance as compared to the initially strengthened beams.

  2. Inverse model for defect characterisation of externally glued CFRP on reinforced concrete structures: comparative study of square pulsed and pulsed thermography

    OpenAIRE

    CRINIERE, Antoine; Dumoulin, Jean; IBARRA CASTANEDO, Clemente; MALDAGUE, Xavier

    2014-01-01

    The objective of the study summarised, hereafter, is to compare square pulsed and pulsed thermography for defect detection and characterisation of carbon fibre-reinforced polymer (CFRP) plates used as structural reinforcement in Civil Engineering applications. For this purpose, two specimens built with cement concrete support were manufactured in the laboratory. They were reinforced with CFRP plates bonded to their surface and different artificial defects were inserted during gluing. Two type...

  3. Recycling of CFRP for high value applications: Effect of sizing removal and environmental analysis of the SuperCritical Fluid Solvolysis

    OpenAIRE

    DAUGUET, Michel; Mantaux, Olivier; PERRY, Nicolas; ZHAO, Yaoyao Fiona

    2015-01-01

    The recycling of Carbon Fibers Reinforced Plastics (CFRP) wastes is becoming increasingly important in the aerospace industry. For most of the technologies, the recycled CF (rCF) are discontinuous, misaligned and unsized. Compared to thermal treatments, the orientation, the length and the brittleness of the rCF are better preserved with the SuperCritical Water Solvolysis (SCWS). The effect of the sizing removal on the recycled CFRP behavior is studied by conducting static characterizations. R...

  4. FE ANALYSIS OF WELDED STEEL BEAM STRENGTHENED BY CFRP%CFRP加固焊接工字钢梁的有限元分析

    Institute of Scientific and Technical Information of China (English)

    赵芳琴; 牛忠荣; 鲁栋; 闫艳

    2009-01-01

    碳纤维增强复合材料(CFRP)加固混凝土结构目前已经得到广泛应用,但在钢结构加回方面应用尚少.通过有限元软件ANSYS对碳纤维布和碳纤维板加固焊接工字钢梁进行变形和应力场分析,得出CFRP片材加固可增强钢梁的刚度,降低钢梁的最大应力.该分析结果可用于钢梁疲劳寿命分析.%A significant number of concrete members were strengthened by carbon fiber reinforced polymer (CFRP). However there are only a few applications in strengthening steel structure with CFRP. In this paper, the influences of CFRP plates and sheets in strengthening steel structure are studied with finite element method (FEM).The computed results show that the CFRP enhance the rigidity and reduce the maximum stress of welded steel beams. The present results can be used to evaluate the fatigue life of welded 1-beam strengthened with CFRP.

  5. Electron radiation effects on Mode II interlaminar fracture toughness of GFRP and CFRP composites

    International Nuclear Information System (INIS)

    The degradation properties of epoxy-based fiber-reinforced-plastics (FRP) composites irradiated by high-energy electrons were studied using the Mode II interlaminar fracture toughness G/sub IIc/, measured by end-notched flexure tests. The radiation-induced degradation mechanisms were investigated through G/sub IIc/ and the scanning electron micrographs of fracture surfaces. For GFRP, the significant decrease in G/sub IIc/ was found. Debonding of glass fibers and epoxy matrix (or degradation of silane coupling agents) plays an important role in degradation in addition to resin degradation. Thus, the improvement of the radiation resistance of fiber-resin interfaces as well as matrix itself is of supreme importance in order to increase the radiation resistance of GFRP. For CFRP, on the other hand, no degradation in fiber-resin interfaces was found and the slight decrease in G/sub IIc/ seems to be due to the resin degradation. 18 references, 6 figures

  6. Development and test verification of the Ariane 4 interstage 2/3 in CFRP

    Science.gov (United States)

    Blaas, C.; Wiggenraad, J. F. M.

    The interstage 2/3 configuration of the Ariane 4 launcher has been redesigned, using the CFRP composite (instead of aluminum) for the curved blade-stiffened panels, in order to reduce weight. Verification analysis of the design was performed using NASTRAN and BOSOR4 models. In experimental tests, flat stiffened panels were tested in compression to verify the selected design details of the cylinder. Three different sizes of subcomponent panels were tested with the objectives of determining the local buckling behavior at room temperature and at 180 C, assessing the strength of the panel to end-ring connections, and establishing the global panel buckling behavior between ring frames. As a result of the tests, the stiffener run-out configuration was modified to prevent premature separation at the tip.

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

    Science.gov (United States)

    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. On acoustic emission for failure investigation in CFRP: Pattern recognition and peak frequency analyses

    Science.gov (United States)

    Gutkin, R.; Green, C. J.; Vangrattanachai, S.; Pinho, S. T.; Robinson, P.; Curtis, P. T.

    2011-05-01

    This paper investigates failure in Carbon Fibre Reinforced Plastics CFRP using Acoustic Emission (AE). Signals have been collected and post-processed for various test configurations: tension, Compact Tension (CT), Compact Compression (CC), Double Cantilever Beam (DCB) and four-point bend End Notched Flexure (4-ENF). The signals are analysed with three different pattern recognition algorithms: k-means, Self Organising Map (SOM) combined with k-means and Competitive Neural Network (CNN). The SOM combined with k-means appears as the most effective of the three algorithms. The results from the clustering analysis follow patterns found in the peak frequencies distribution. A detailed study of the frequency content of each test is then performed and the classification of several failure modes is achieved.

  9. Experimental study and analysis on fatigue stiffness of RC beams strengthened with CFRP and steel plate

    Institute of Scientific and Technical Information of China (English)

    LU Yi-yan; HU Ling; LI Shan; WANG Kang-hao

    2016-01-01

    The objective of this work is to investigate the fatigue behavior of reinforced concrete (RC) beams strengthened with externally bonded carbon fiber reinforced polymer (CFRP) and steel plate. An experimental investigation and theoretical analysis were made on the law of deflection development and stiffness degradation, as well as the influence of fatigue load ranges. Test results indicate that the law of three-stage change under fatigue loading is followed by both midspan deflection and permanent deflection, which also have positive correlation with fatigue load amplitude. Fatigue stiffness of composite strengthened beams degrades gradually with the increasing of number of cycles. Based on the experimental results, a theoretical model by effective moment of inertia method is developed for calculating the sectional stiffness of such composite strengthened beams under fatigue loading, and the calculated results are in good agreement with the experimental results.

  10. Field tests of Fibre Bragg Grating sensors incorporated into CFRP for Railway Bridge strengthening condition monitoring

    DEFF Research Database (Denmark)

    Täljsten, Björn; Kerrouche, Abdelfathe; Leighton, J; Boyle, W.J.O; Gebremichael, Y.M; Sun, Tong; Grattan, K.T.V; Bennitz, Anders

    2008-01-01

    made with the FBG- based system were found to be in agreement with the changes expected in the structure (together with the embedded reinforcement), produced by the loading applied. The study has demonstrated the successful use of FBG-based technology pre-mounted in ‘smart’ carbon fiber composite...... project ‘Sustainable Bridges’. The FBG sensors were embedded in Carbon Fibre Reinforced Polymers (CFRP) rods incorporated into grooves specially created in the concrete cover of the bridge structure and interrogated using a compact system based on Wavelength Division Multiplexing (WDM). Throughout the...... study, the FBG sensors were continuously monitored, allowing the incremental increases in the strain to be seen and through the yield point of the carbon composite reinforcement. The sensors were able to follow the resulting induced changes in strain of over a range in excess of 4000µε. The measurements...

  11. High Stability CFRP Support Structure for Ka Band Multi-Spot Cluster

    Science.gov (United States)

    Yarza, A.; Cano, J.; Ozores, E.

    2012-07-01

    In the recent days, Ka band mission are being implemented for telecommunication satellites as emergent technology. EADS CASA Espacio (ASTRIUM) has been doing developments able to face up the demanding requirements associated to this frequency band where aspects such as in orbit stability o manufacturing accuracy are essential. Once it has been demonstrated the capability to offer excellent antenna reflectors with low mass, very low ohmic losses, excellent RF performances and very stable in orbit thermoelastic behaviour, improvements at feeder-chain level have been developed with the aim to cover the global antenna mission with excellent performances. This paper presents the product developed to accommodate a KA band multi-spot cluster to cover a telecommunication mission. It includes a description of the tasks carried out until the current development status, with the definition of the mechanical specification used as applicable and the solutions applied to meet the requirements. A CFRP structure is proposed with the aim to achieve a light mass concept, structurally speaking optimized and capable to assemble multiple feeder chain and make independent the thermomechanical behaviour of each one. Moreover, the design with CFRP leads to very stable thermoelastic behaviour of the assembly and the feeder-chain with the scope to guaranty the stability of the RF-beam for the correct electrical performances. The compatibility between the carbon fibre structure and the Aluminium feeder chain is solved by means of isostatic devices that are capable to absorb the thermal stresses coming from the different thermal expansion coefficients of the materials used. The proposed design is to be confirmed over a Qualification Model, already manufactured, with the scope to be implemented as flight hardware in a commercial spacecraft. The product is to be tested in a full qualification environmental test campaign where the capability to withstand the dynamic loads and the thermal

  12. Adhesive Wear Performance of CFRP Multilayered Polyester Composites Under Dry/wet Contact Conditions

    Science.gov (United States)

    Danaelan, D.; Yousif, B. F.

    The tribo-performance of a new engineering composite material based on coconut fibers was investigated. In this work, coconut fibers reinforced polyester (CFRP) composites were developed. The tribo-experiments were conducted by using pin-on-disc machine under dry and wet sliding contact condition against smooth stainless steel counterface. Worn surfaces were observed using optical microscope. Friction coefficient and specific wear rate were presented as a function of sliding distance (0-0.6 km) at different sliding velocities (0.1-0.28 m/s). The effect of applied load and sliding velocity was evaluated. The results showed that all test parameters have significant influence on friction and wear characteristics of the composites. Moreover, friction coefficient increased as the normal load and speed increased, the values were about 0.7-0.9 under dry contact condition. Meanwhile, under wet contact condition, there was a great reduction in the friction coefficient, i.e. the values were about 0.1-0.2. Furthermore, the specific wear rates were found to be around 2-4 (10-3) mm3/Nm under dry contact condition and highly reduced under wet condition. In other words, the presence of water as cleaner and polisher assisted to enhance the adhesive wear performance of CFRP by about 10%. The images from optical microscope showed evidence of adhesive wear mode with transition to abrasive wear mode at higher sliding velocities due to third body abrasion. On the other hand, optical images for wet condition showed less adhesive wear and smooth surfaces.

  13. Analysis of Influence of CFRP Embeded Length on Bending Performance of RC Beams Strengthened with Near Surface Mounted CFRP Strips%CFRP嵌条长度对加固RC梁抗弯性能影响的分析

    Institute of Scientific and Technical Information of China (English)

    唐忠亮; 陆洲导; 余江滔; 刘媛

    2012-01-01

    The near surfaced mounted ( NSM) method of CFRP strips is a new effective method used to strengthen structural components. Based on the tests carried on 5 beams strengthened with the NSM method, this paper investigates the effect of CFRP embeded length on failure modes and the ultimate bearing capacity of strengthened RC beams with the help of ABAQUS. The comparing results show that the ABAQUS can simulate accurately the failure mode, ultimate bearing capacity,concrete strain of the actual RC beams. From the simulation , It is also found that CFRP strips can maintain useful in preventing the growing of deflection after steel yielding with the increasing of CFRP strips' length.%内嵌CFRP板条加固钢筋混凝土梁在结构加固中是一种新兴的、经济有效的方法.以5根CFRP嵌入法加固RC梁的抗弯性能试验为依据,采用ABAQUS有限元分析软件模拟嵌帖长度对RC梁破坏模式及承载能力的影响.模拟结果在构件破坏模式、承载力、混凝土应变等指标上均与试验结果能较好吻合,且由模拟结果能够看出,随着嵌条长度的增大,CFRP的贡献会持续存在,钢筋屈服后挠度增大的情况得以改善.

  14. Application of a novel optical fiber sensor to detection of acoustic emissions by various damages in CFRP laminates

    International Nuclear Information System (INIS)

    In this research, we applied a novel optical fiber sensor, phase-shifted fiber Bragg grating balanced sensor with high sensitivity and broad bandwidth, to acoustic emission (AE) detection in carbon fiber reinforced plastics (CFRPs). AE signals generated in the tensile testing of angle-ply and cross-ply CFRP laminates were both detected by the novel optical fiber sensor and traditional PZT sensors. The cumulative hits detected by both sensors coincided after applying simple data processing to eliminate the noise, and clearly exhibited Kaiser effect and Felicity effect. Typical AE signals detected by both sensors were discussed and were tried to relate to micro CFRP damages observed via microscope. These results demonstrate that this novel optical fiber sensor can reliably detect AE signals from various damages. It has the potential to be used in practical AE detection, as an alternative to the piezoelectric PZT sensor. (paper)

  15. Ensayos de resistencia de pórticos de concreto a escala, reforzados con CFRP en los nudos

    Directory of Open Access Journals (Sweden)

    Andrés Duque

    2011-06-01

    Full Text Available The results of an experimental study of four scale concrete frames (1:2 subjected to monotonic load are presented. The four frames were designed and constructed without confinement zones in the joints and considering only the gravitational load. Two of the four concrete frames of concrete were reinforced in the joints with a confinement with polymers reinforced with carbon fiber (CFRP. The instrumentation of the tests consisted of a load cell, analogous deformimeters and strain gages in the reinforcement steel bars and in the carbonfibers. According to the experimental results, the reinforcement with fibers duplicates the resistance and the rigidity of the frames and increases its total displacement without loss of resistance in 60%.Also the confinement of the joints with CFRP diminishes remarkably the fissures and the cracks of the structural elements.

  16. Process-induced Distortions in CFRP Manufacturing: A bottle-neck for high-rate Production Scenarios

    OpenAIRE

    Kappel, Erik; Stefaniak, Daniel; Hühne, Christian

    2014-01-01

    Undesired process-induced distortions (PID) are an inherent issue in today's CFRP manufacturing scenarios. Distortions are inevitable due to an interaction of composite-specific and process-specific parameters. In academia it is distinguished in three main phenomena Spring-in, Warpage and Forced- interaction while their specific relevance depends on the part shape at hand. As process distortions remain widely unconsidered in current partdevelopment chains, they induce considera...

  17. Efficient processing of CFRP with a picosecond laser with up to 1.4 kW average power

    Science.gov (United States)

    Onuseit, V.; Freitag, C.; Wiedenmann, M.; Weber, R.; Negel, J.-P.; Löscher, A.; Abdou Ahmed, M.; Graf, T.

    2015-03-01

    Laser processing of carbon fiber reinforce plastic (CFRP) is a very promising method to solve a lot of the challenges for large-volume production of lightweight constructions in automotive and airplane industries. However, the laser process is actual limited by two main issues. First the quality might be reduced due to thermal damage and second the high process energy needed for sublimation of the carbon fibers requires laser sources with high average power for productive processing. To achieve thermal damage of the CFRP of less than 10μm intensities above 108 W/cm² are needed. To reach these high intensities in the processing area ultra-short pulse laser systems are favored. Unfortunately the average power of commercially available laser systems is up to now in the range of several tens to a few hundred Watt. To sublimate the carbon fibers a large volume specific enthalpy of 85 J/mm³ is necessary. This means for example that cutting of 2 mm thick material with a kerf width of 0.2 mm with industry-typical 100 mm/sec requires several kilowatts of average power. At the IFSW a thin-disk multipass amplifier yielding a maximum average output power of 1100 W (300 kHz, 8 ps, 3.7 mJ) allowed for the first time to process CFRP at this average power and pulse energy level with picosecond pulse duration. With this unique laser system cutting of CFRP with a thickness of 2 mm an effective average cutting speed of 150 mm/sec with a thermal damage below 10μm was demonstrated.

  18. Ensayos de resistencia de pórticos de concreto a escala, reforzados con CFRP en los nudos

    OpenAIRE

    Andrés Duque; Ingrid Amazo; Daniel Ruiz

    2011-01-01

    The results of an experimental study of four scale concrete frames (1:2) subjected to monotonic load are presented. The four frames were designed and constructed without confinement zones in the joints and considering only the gravitational load. Two of the four concrete frames of concrete were reinforced in the joints with a confinement with polymers reinforced with carbon fiber (CFRP). The instrumentation of the tests consisted of a load cell, analogous deformimeters and strain gages in the...

  19. Numerical simulations and experimental investigations on quasi-static and cyclic mixed mode delamination of multidirectional CFRP laminates

    OpenAIRE

    Naghipour, Parya

    2011-01-01

    The structural applications of Carbon Fibre Reinforced Plastic (CFRP) composites are gradually expanding in aerospace industry as a result of their outstanding mechanical properties such as high stiffness to weight ratio and fatigue resistance. With the increasing application, the need for understanding their mechanical behaviour and failure mechanisms also rises. Interfacial cracking between layers or delamination is one of the most common failure types in laminated fibre-reinforced composit...

  20. Scanning tone burst eddy-current thermography (S-TBET) for NDT of carbon fiber reinforced plastic (CFRP) components

    Science.gov (United States)

    Libin, M. N.; Maxfield, B. W.; Balasubramanian, Krishnan

    2014-02-01

    Tone Burst Eddy Current technique uses eddy current to apply transient heating inside a component and uses a conventional IR camera for visualization of the response to the transient heating. This technique has been earliest demonstrated for metallic components made of AL, Steel, Stainless Steel, etc., and for detection of cracks, corrosion and adhesive dis-bonds. Although, not nearly as conducting as metals, the Carbon Fibre Reinforced Plastic (CFRP) material absorbs measurable electromagnetic radiation in the frequency range above 10 kHz. When the surface temperature is observed on the surface that is being heated (defined as the surface just beneath and slightly to one side of the heating coil), the surface temperature increases with increasing frequency because the internal heating increases with frequency. A 2-D anisotropic transient Eddy current heating and thermal conduction model has been developed that provides a reasonable description of the processes described above. The inherent anisotropy of CFRP laminates is included in this model by calculating the heating due to three superimposed, tightly coupled isotropic layers having a specified ply-layup. The experimental apparatus consists of an induction heating coil and an IR camera with low NETD and high frame rates. The coil is moved over the sample using a stepper motor controlled manipulator. The IR data recording is synchronized with the motion control to provide a movie of the surface temperature over time. Several components were evaluated for detection of impact damage, location of stiffeners, etc. on CFRP components.

  1. TECHNICAL NOTE: Low-cost delamination monitoring of CFRP beams using electrical resistance changes with neural networks

    Science.gov (United States)

    Todoroki, Akira; Ueda, Masahito

    2006-08-01

    Delamination is a significant defect of laminated composites. The present study employs an electrical resistance change method in an attempt to identify internal delaminations experimentally. The method adopts reinforcing carbon fibers as sensors. In our previous paper, an actual delamination crack in a carbon fiber reinforced plastic (CFRP) laminate was experimentally identified with artificial neural networks (ANNs) or response surfaces created from a large number of experiments. The experimental results were used for the learning of the ANN or for regressions of the response surfaces. For the actual application of the method, it is necessary to minimize the number of experiments in order to keep the cost of the experiments to a minimum. In the present study, therefore, finite-element method (FEM) analyses are employed to make sets of data for the learning of the ANN. First, the electrical conductivity of the CFRP laminate is identified by means of the least estimation error method. After that, the results of the FEM analyses are used for the learning of the ANN. The method is applied to the actual delamination monitoring of CFRP beams. As a result, the method successfully monitored the delamination location and size using only ten experiments.

  2. Scanning tone burst eddy-current thermography (S-TBET) for NDT of carbon fiber reinforced plastic (CFRP) components

    International Nuclear Information System (INIS)

    Tone Burst Eddy Current technique uses eddy current to apply transient heating inside a component and uses a conventional IR camera for visualization of the response to the transient heating. This technique has been earliest demonstrated for metallic components made of AL, Steel, Stainless Steel, etc., and for detection of cracks, corrosion and adhesive dis-bonds. Although, not nearly as conducting as metals, the Carbon Fibre Reinforced Plastic (CFRP) material absorbs measurable electromagnetic radiation in the frequency range above 10 kHz. When the surface temperature is observed on the surface that is being heated (defined as the surface just beneath and slightly to one side of the heating coil), the surface temperature increases with increasing frequency because the internal heating increases with frequency. A 2-D anisotropic transient Eddy current heating and thermal conduction model has been developed that provides a reasonable description of the processes described above. The inherent anisotropy of CFRP laminates is included in this model by calculating the heating due to three superimposed, tightly coupled isotropic layers having a specified ply-layup. The experimental apparatus consists of an induction heating coil and an IR camera with low NETD and high frame rates. The coil is moved over the sample using a stepper motor controlled manipulator. The IR data recording is synchronized with the motion control to provide a movie of the surface temperature over time. Several components were evaluated for detection of impact damage, location of stiffeners, etc. on CFRP components

  3. Scanning tone burst eddy-current thermography (S-TBET) for NDT of carbon fiber reinforced plastic (CFRP) components

    Energy Technology Data Exchange (ETDEWEB)

    Libin, M. N.; Maxfield, B. W.; Balasubramanian, Krishnan [Centre for Nondestructive Evaluation, Indian Institute of Technology Madras, Chennai 600036 (India)

    2014-02-18

    Tone Burst Eddy Current technique uses eddy current to apply transient heating inside a component and uses a conventional IR camera for visualization of the response to the transient heating. This technique has been earliest demonstrated for metallic components made of AL, Steel, Stainless Steel, etc., and for detection of cracks, corrosion and adhesive dis-bonds. Although, not nearly as conducting as metals, the Carbon Fibre Reinforced Plastic (CFRP) material absorbs measurable electromagnetic radiation in the frequency range above 10 kHz. When the surface temperature is observed on the surface that is being heated (defined as the surface just beneath and slightly to one side of the heating coil), the surface temperature increases with increasing frequency because the internal heating increases with frequency. A 2-D anisotropic transient Eddy current heating and thermal conduction model has been developed that provides a reasonable description of the processes described above. The inherent anisotropy of CFRP laminates is included in this model by calculating the heating due to three superimposed, tightly coupled isotropic layers having a specified ply-layup. The experimental apparatus consists of an induction heating coil and an IR camera with low NETD and high frame rates. The coil is moved over the sample using a stepper motor controlled manipulator. The IR data recording is synchronized with the motion control to provide a movie of the surface temperature over time. Several components were evaluated for detection of impact damage, location of stiffeners, etc. on CFRP components.

  4. EXPERIMENTAL INVESTIGATION ON THE EFFECT OF NATURAL TROPICAL WEATHER ON INTERFACIAL BONDING PERFORMANCE OF CFRP-CONCRETE BONDING SYSTEM

    Directory of Open Access Journals (Sweden)

    MOHD H. MOHD HASHIM

    2016-04-01

    Full Text Available The existing reinforced concrete structures may require rehabilitation and strengthening to overcome deficiencies due to defect and environmental deterioration. Fibre Reinforced Polymer (FRP-concrete bonding systems can provide solution for the deficiencies, but the durability of the bonded joint needs to be investigated for reliable structural performance. In this research the interfacial bonding behaviour of CFRP-concrete system under tropical climate exposure is main interest. A 300 mm concrete prism was bonded with CFRP plate on its two sides and exposed for 3, 6, and 9 months to laboratory environment, continuous natural weather, and wet-dry exposure in 3.5% saltwater solution at room and 40 °C temperature. The prisms were subjected to tension and compression load under bonding test to measure the strain and determine stress distribution and shear stress transfer behaviour. The results of the bonding test showed that load transfer was fairly linear and uniform at lower load level and changed to non-linear and non- uniform at higher load level. The force transfers causes the shear stress distribution being shifted along the bonded length. The combination of climate effects may have provided better curing of the bonded joints, but longer duration of exposure may be required to weaken the bond strength. Nevertheless, CFRP-concrete bonding system was only minimally affected under the tropical climate and salt solution.

  5. Measurement of Temperature and Residual Strain during Fatigue of a CFRP Composite Using Fiber Bragg Grating Sensors

    Institute of Scientific and Technical Information of China (English)

    SHEN Xiaoyan; LIN Yuchi; WANG Wei

    2009-01-01

    Fatigue behaviour has important implications for engineering composite structures in sectors ranging from automotive to aerospace. Optical sensing technology displays excellent performance in these fields for monitoring. In this paper, temperature and residual strain during fatigue of a carbon fiber reinforced polymer(CFRP) are investigated. Four autoclaved CFRP beam specimens, with fiber Bragg grating(FBG) sensors and thermocouples embedded at selected locations, are subjected to three-point bending cyclic loading on the BOSE testing machine for fatigue testing. Thermocouples are used to measure the temperature while FBGs can sense the temperature and strain as well. Seven tests in total are conducted at different frequencies, and each test lasts for several days. From the experimental results, transient steep peaks of temperature increases (up to 2.3 ℃) are discovered at the beginning of the load. The following constant temperature increments are around 1.0 ℃, which is not relevant to frequencies from 0.1 Hz to 20 Hz and suspected due to fatigue. Residual strains of 1×10-5-2×10-5 during fatigue, fading away rapidly when unloading, are also reported. Embedded FBGs here are validated to sense temperature and strains in composite structures, which demonstrates promising potentials in structure monitoring fields. CFRP are verified to have an excellent performance during fatigue with low temperature increase and residual strain.

  6. Performances of super-long span prestressed cable-stayed bridge with CFRP cables and RPC girder

    Institute of Scientific and Technical Information of China (English)

    Fang Zhi; Fan Fenghong; Ren Liang

    2013-01-01

    To discuss the applicability of advanced composite carbon fiber reinforced polymer (CFRP) and ultra-high performance concrete reactive powder concrete (RPC) in super-long span cable-stayed bridges , taking a 1 008 m cable-stayed bridge with steel girders and steel cables as an example,a new cable-stayed bridge in the same span with RPC girders and CFRP cables was designed,in which the cable’s cross section was determined by the principle of equivalent cable capacity and the girder’s cross section was determined in virtual of its stiffness, shear capacity and local stability. Based on the methods of finite element analysis,the comparative analysis of these two cable-stayed bridge schemes about static performances,dynamic performances,stability and wind resis-tance behavior were carried out. The results showed that it was feasible to form a highly efficient,durable concrete cable-stayed bridge with RPC girders and CFRP cables and made its applicable span range expand to 1 000 m long around.

  7. Acoustic Emission Monitoring of Compression-after-Impact Test of Nano-Particles-Coated CFRP Damaged by Simulated Lightning Strikes

    International Nuclear Information System (INIS)

    Nanoparticles-coated and impact-damaged carbon-fiber reinforced plastics(CFRP) laminates were tested under compression-after-impact(CAI) mode and the propagation of damage due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. CFRP laminates were made of carbon prepregs prepared by coating of conductive nano-particles directly on the fibers and the coupons were subjected to simulated lightning strikes with a high voltage/current impulse of 10∼40 kA within a few microseconds. The effects of nano-particles coating and the degree of damage induced by the simulated lightning strikes on the AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terns of damage area by using ultrasonic C-scan images. From the results assessed during the CAI tests of damaged CFRP showed that AE monitoring appeared to be very useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes

  8. Assessment of alternative joining techniques for Ti–6Al–4V/CFRP hybrid joints regarding tensile and fatigue strength

    International Nuclear Information System (INIS)

    Highlights: • Nd:YAG laser riveting of Ti–6Al–4V/CFRP lap joint was successfully realized. • Tensile strength is comparable to that of conventional riveted lap joints. • Fatigue strength of conventional riveted joint can be increased by adhesive bonding. • The effect of adhesive bonding is comparable to surface structuring of Ti–6Al–4V. - Abstract: CFRP and titanium joints are used in the aerospace industry. These materials are usually joined by titanium rivets which are inserted into holes drilled through both materials. Conventional riveted hybrid joints of CFRP and titanium parts fail under quasi static loading due to the uneven load distribution at the titanium rivets. Under cyclic loading, the fatigue failure occurs mainly in the titanium part because of the higher notch sensitivity. The aim of this work is the comparison of different joining concepts in terms of stiffness, strength and fatigue limit. First, laser riveting, here titanium pins are Nd:YAG laser beam welded to the Ti–6Al–4V parts. Second, conventional riveted hybrid joint is combined with adhesive bonding. Third, surface structuring of the Ti–6Al–4V parts is used to enhance friction in the riveted joint. Tensile and fatigue tests as well as fractographical examinations are performed to establish the process–property–performance relationship of the hybrid joints. Laser riveting leads to higher stiffness but equal strength, when compared to conventional riveted joints. Fatigue life is improved by the implementation of adhesive bonding and surface structuring

  9. Strength Analysis of Sandwitch Panels with CFRP Quasi Isotropic Layup or Isotropic Material Facesheets in Dynamic Environment Using MSC Nastran and SineMOS

    Science.gov (United States)

    Di Carlo, A.; Carbonell Garcia, A.

    2012-07-01

    The frequency response solution (SOL 111) of MSC Nastran versions prior to 2012 only allows the output of element stress components and element forces and does not allow the calculation of composite failure indices or Von-Mises stress for metallic parts. The analysis of a sandwich panel comprises several strength verifications, such as the check of facesheet and core failure as well as the check of facesheet and core local stability (shear crimping, wrinkling). In static analysis (SOL 101), MSC Nastran provides failure index output which can be used to generate fringe plots of Margins of Safety (MoS) in any post- processing tool. The other verifications (core strength and local stability) must be performed using different tools. For the dynamic analysis of sandwich panels, an analysis technique based on element forces and on failure envelope at laminate level has been developed and implemented in a Fortran program (SineMOS) which allows evaluating facesheet and core failure as well as local stability, taking into account modulus and phase information of the element forces. SineMOS is able to produce files containing information used to generate plots of minimum Margin of Safety in Patran for each failure mode. This paper shows the various steps of the analysis process, starting from the building of the failure envelope for the CFRP facesheet laminate. Finally some validation example is shown, comparing SineMOS results with results based on the application of static displacements to the nodes of the model.

  10. Structural Diagnostics of CFRP Composite Aircraft Components by Ultrasonic Guided Waves and Built-In Piezoelectric Transducers

    Energy Technology Data Exchange (ETDEWEB)

    Howard M. Matt

    2007-02-15

    To monitor in-flight damage and reduce life-cycle costs associated with CFRP composite aircraft, an autonomous built-in structural health monitoring (SHM) system is preferred over conventional maintenance routines and schedules. This thesis investigates the use of ultrasonic guided waves and piezoelectric transducers for the identification and localization of damage/defects occurring within critical components of CFRP composite aircraft wings, mainly the wing skin-to-spar joints. The guided wave approach for structural diagnostics was demonstrated by the dual application of active and passive monitoring techniques. For active interrogation, the guided wave propagation problem was initially studied numerically by a semi-analytical finite element method, which accounts for viscoelastic damping, in order to identify ideal mode-frequency combinations sensitive to damage occurring within CFRP bonded joints. Active guided wave tests across three representative wing skin-to-spar joints at ambient temperature were then conducted using attached Macro Fiber Composite (MFC) transducers. Results from these experiments demonstrate the importance of intelligent feature extraction for improving the sensitivity to damage. To address the widely neglected effects of temperature on guided wave base damage identification, analytical and experimental analyses were performed to characterize the influence of temperature on guided wave signal features. In addition, statistically-robust detection of simulated damage in a CFRP bonded joint was successfully achieved under changing temperature conditions through a dimensionally-low, multivariate statistical outlier analysis. The response of piezoceramic patches and MFC transducers to ultrasonic Rayleigh and Lamb wave fields was analytically derived and experimentally validated. This theory is useful for designing sensors which possess optimal sensitivity toward a given mode-frequency combination or for predicting the frequency dependent

  11. Interfacial stresses in damaged RC beams strengthened with externally bonded CFRP plate

    Energy Technology Data Exchange (ETDEWEB)

    Benrahou, K.H. [Laboratoire des Materiaux et Hydrologie, Universite de Sidi Bel Abbes, BP 89 Cite Ben M' hidi 22000 Sidi Bel Abbes (Algeria); Adda bedia, E.A. [Laboratoire des Materiaux et Hydrologie, Universite de Sidi Bel Abbes, BP 89 Cite Ben M' hidi 22000 Sidi Bel Abbes (Algeria)]. E-mail: addabed@yahoo.com; Benyoucef, S. [Laboratoire des Materiaux et Hydrologie, Universite de Sidi Bel Abbes, BP 89 Cite Ben M' hidi 22000 Sidi Bel Abbes (Algeria); Tounsi, A. [Laboratoire des Materiaux et Hydrologie, Universite de Sidi Bel Abbes, BP 89 Cite Ben M' hidi 22000 Sidi Bel Abbes (Algeria); Benguediab, M. [Laboratoire des Materiaux et Hydrologie, Universite de Sidi Bel Abbes, BP 89 Cite Ben M' hidi 22000 Sidi Bel Abbes (Algeria)

    2006-09-25

    A theoretical method to predict the interfacial stresses in the adhesive layer of damaged reinforced concrete beams strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) plate is presented. The adopted model is developed including the adherend shear deformations by assuming a linear shear stress through the depth of the RC beam [A. Tounsi, Int. J. Solids Struct., in press], while all existing solutions neglect this effect [e.g. S. Benyoucef, A. Tounsi, S.A. Meftah, E.A. Adda Bedia, Compos. Interfaces, in press; S.T. Smith, J.G. Teng, Eng. Struct. 23 (7) (2001) 857-871; T.M. Roberts, Struct. Eng. 67 (12) (1989) 229-233; A. Tounsi, S. Benyoucef, Int. J. Adhes. Adhes., in press; T. Stratford, J. Cadei, Construct. Building Mater. 20 (2006) 34-35]. In addition, in the present study the anisotropic damage model is adopted to describe the damage of the RC beams. It is shown that the damage has a significant effect on the interfacial stresses in FRP-damaged RC beam.

  12. Calibrated Heat Flow Model for Determining the Heat Conduction Losses in Laser Cutting of CFRP

    Science.gov (United States)

    Mucha, P.; Weber, R.; Speker, N.; Berger, P.; Sommer, B.; Graf, T.

    Laser machining has great potential regarding automation in fabrication of CFRP (carbon-fiber-reinforced plastics) parts, due to the nearly force and tool-wear free processing at high process speeds. The high vaporization temperatures and the large heat conductivity of the carbon fibers lead to a large heat transport into the sample. This causes the formation of a heat-affected zone and a decrease of the process speed. In the present paper,an analytical heat flow model was adapted in order to understand and investigate the heat conduction losses. Thermal sensors were embedded in samples at different distances from the kerf to fit the calculated to the measured temperatures. Heat conduction losses of up to 30% of the laser power were determined. Furthermore, the energy not absorbed by the sample, the energy for sublimating the composite material in the kerf, the energy for the formation of the HAZ, and the residual heat in the sample are compared in an energy balance.

  13. Influence of Terahertz Waves on Unidirectional Carbon Fibers in CFRP Composite Materials

    Directory of Open Access Journals (Sweden)

    Kwang-Hee IM

    2014-12-01

    Full Text Available Terahertz time domain spectroscopy (THz TDS system based on the reflective and through-transmission modes was utilized. Influence of terahertz waves (T-ray on the fiber surface layups in the CFRP solid composites was studied. It was found that the value of electrical conductivity in the carbon fibers varies by the layup directions of carbon fibers based on E-field (Electrical field. T-ray optimized scanning data could be obtained at the 90° angle normal to the E-field direction. GFRP (Glass-fiber reinforced plastics composite laminates were scanned with two saw cuts using a T-ray THz TDS system and the terahertz optimized scanning images were obtained at the angles normal to the E-field direction on the nonconducting materials. Also, by use of 2-dimensional spatial Fourier transform, interface C-scan images were transformed into quantitative angular distribution plots in order to show the fiber orientation information therein and to make the orientation of the ply predictable. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6440

  14. Radiation resistance of GFRP and CFRP using bisphenol A system epoxy as matrix

    International Nuclear Information System (INIS)

    The use of fiber-reinforced plastics as structural materials is increasing, but they are apt to be affected by the environment of their use unlike metals. When FRPs are used as the material requiring endurance, the resin composing the FRPs deteriorates due to radiation, and it causes the lowering of the characteristics of the FRPs. Accordingly, it is very important to evaluate the radiation resistance of FRPs and to understand the mechanism of deterioration. In this study, the deterioration due to electron beam irradiation and its mechanism of glass fiber reinforced plastics (GFRP) and carbon fiber reinforced plastics (CFRP) using bisphenol A system epoxy as the matrix were evaluated by bending strength test, rate of boiling water absorption test and scanning acoustic microscope observation, and the radiation resistance based on the difference of fiber materials was examined. The samples, the irradiation using a Dynamitron electron accelerator, the above mentioned testing methods and the results are reported. The nondestructive information on interface separation, microvoids and cracks in the matrix was given by acoustic microscope images. (K.I.)

  15. Surface Irregularity Factor as a Parameter to Evaluate the Fatigue Damage State of CFRP

    Directory of Open Access Journals (Sweden)

    Pablo Zuluaga-Ramírez

    2015-11-01

    Full Text Available This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL and realistic variable amplitude loads (VAL, representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications.

  16. Optimisation of the rivet joints of the CFRP composite material and aluminium alloy

    Directory of Open Access Journals (Sweden)

    A. Czulak

    2007-01-01

    Full Text Available Purpose: The project included analysis of strain, cracking, and failure of riveted joints of plate elements madefrom the carbon-fibre-reinforced plastics (CFRP and from the 6061 aluminium alloy.Design/methodology/approach: The modelled static tensile strength test carried out for the plates from CFRPand from the 6061 aluminium alloy joined with the steel rivet. Computer simulation was carried out with IDEASsoftware package employing the FEM.Findings: Simulations using the mesh with a bigger number of FEM elements do not yield better accuracy ofcalculations and do not improve convergence with the results of laboratory experiments. Only the calculationtime gets longer. Computer simulation has also show that the type of contacts employed between elementsaffects the results significantly.Research limitations/implications: For the composite materials, joints between materials and computersimulation examinations are planed.Practical implications: Results obtained for the mesh with 4 and 5 FEM elements are the closest to the resultsof laboratory experiments, which is confirmed by the strain plot. Simulations using the mesh with a biggernumber of FEM elements do not yield better accuracy of calculations and do not improve convergence with theresults of laboratory experiments. Only the calculation time gets longer. Computer simulation has show that thetype of contacts employed between elements affects the results significantly.Originality/value: The paper presents influence of fibre mesh closeness on convergence of the results with laboratorytests. Simulation results were collected and compared with the laboratory static tensile strength tests results.

  17. Electrical Resistance and Acoustic Emission Measurements for Monitoring the Structural Behavior of CFRP Laminate

    KAUST Repository

    Zhou, Wei

    2015-07-12

    Electrical resistance and acoustic emission (AE) measurement are jointly used to monitor the degradation in CFRP laminates subjected to tensile tests. The objective of this thesis is to perform a synergertic analysis between a passive and an active methods to better access how these perform when used for Structural Health Moni- toring (SHM). Laminates with three different stacking sequences: [0]4, [02/902]s and [+45/ − 45]2s are subjected to monotonic and cyclic tensile tests. In each laminate, we carefully investigate which mechanisms of degradation can or cannot be detect- ed by each technique. It is shown that most often, that acoustic emission signals start before any electrical detection is possible. This is is explained based on the redundance of the electrical network that makes it less sensitive to localized damages. Based on in depth study of AE signals clustering, a new classification is proposed to recognize the different damage mechanims based on only two parameters: the RA (rise time/amplitude) and the duration of the signal.

  18. ULTRASONIC INFLUENCE OF POROSITY LEVEL ON CFRP COMPOSITE LAMINATES USING RAYLEIGH PROBE WAVES

    Institute of Scientific and Technical Information of China (English)

    Je-Woong Park; Do-Jung Kim; Kwang-Hee Im; Sang-Kyu Park; David K.Hsu; Adam H.Kite; Sun-Kyu Kim; Kil-Sung Lee; In-Young Yang

    2008-01-01

    It was found that a pitch-catch signal was more sensitive than normal incidence backwall echo of longitudinal wave to subtle flaw conditions in the composites (damages,fiber orientation,low level porosity,ply waviness,and cracks).Both the strength and stiffness depend on the fiber orientation and porosity volume in the composites.The porosity content of a composite structure is critical to the strength and performance of the structure in general.The depth of the sampling volume where the pitch-catch signal came from was relatively shallow with the head to-head miniature Rayleigh probes,but the depth can be increased by increasing the separation distance of the transmitting and receiving probes.Also,a method was utilized to determine the porosity content of a composite lay-up by processing micrograph images of the laminate.A free software package was utilized to process micrograph images of the test sample.The results from the image processing method were compared with existing data.Beam profile was characterized in unidirectional CFRP(carbon fiber reinforced plastics) using pitch-catch Rayleigh probes and the one-sided pitch-catch technique was utilized to produce C-scan images with the aid of the automatic scanner.

  19. Interfacial stresses in damaged RC beams strengthened with externally bonded CFRP plate

    International Nuclear Information System (INIS)

    A theoretical method to predict the interfacial stresses in the adhesive layer of damaged reinforced concrete beams strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) plate is presented. The adopted model is developed including the adherend shear deformations by assuming a linear shear stress through the depth of the RC beam [A. Tounsi, Int. J. Solids Struct., in press], while all existing solutions neglect this effect [e.g. S. Benyoucef, A. Tounsi, S.A. Meftah, E.A. Adda Bedia, Compos. Interfaces, in press; S.T. Smith, J.G. Teng, Eng. Struct. 23 (7) (2001) 857-871; T.M. Roberts, Struct. Eng. 67 (12) (1989) 229-233; A. Tounsi, S. Benyoucef, Int. J. Adhes. Adhes., in press; T. Stratford, J. Cadei, Construct. Building Mater. 20 (2006) 34-35]. In addition, in the present study the anisotropic damage model is adopted to describe the damage of the RC beams. It is shown that the damage has a significant effect on the interfacial stresses in FRP-damaged RC beam

  20. Behavior of Reinforced Concrete Box Beam Strengthened with CFRP U-Wrap Strips Under Torsion

    Directory of Open Access Journals (Sweden)

    Ma Shengqiang

    2016-01-01

    Full Text Available The present study focuses on the torsional strengthening behavior of reinforced concrete (RC box section beams that are widely used in bridges. Four RC box beams were fabricated, and three of them were wrapped by carbon fiber-reinforced polymer (CFRP U-wrap strips with or without longitudinal strips. The different wrapping configuration, cracking angle, failure pattern, and tensile strain of fibers were investigated and discussed accordingly. The experimental results addressed that U-wrap strips strengthening also can upgrade the ultimate torque of beams moderately. In particular, using U-wrap and longitudinal strips to bond the box beams increased the torsional stiffness slightly. The same equation from different codes for calculating RC specimens can accurately predict the ultimate strength of the control beam, but the calculation of the fib model overestimated the torsional strengthening improvement of the wrapped specimens. However, Ghobarah et al. assumed approximately 3000με of the average ultimate fiber strain in calculating the ultimate strength of the wrapped box beams which shows in relatively appropriate agreement with testing results.

  1. Damage Modes Recognition and Hilbert-Huang Transform Analyses of CFRP Laminates Utilizing Acoustic Emission Technique

    Science.gov (United States)

    WenQin, Han; Ying, Luo; AiJun, Gu; Yuan, Fuh-Gwo

    2016-04-01

    Discrimination of acoustic emission (AE) signals related to different damage modes is of great importance in carbon fiber-reinforced plastic (CFRP) composite materials. To gain a deeper understanding of the initiation, growth and evolution of the different types of damage, four types of specimens for different lay-ups and orientations and three types of specimens for interlaminar toughness tests are subjected to tensile test along with acoustic emission monitoring. AE signals have been collected and post-processed, the statistical results show that the peak frequency of AE signal can distinguish various damage modes effectively. After a AE signal were decomposed by Empirical Mode Decomposition (EMD) method, it may separate and extract all damage modes included in this AE signal apart from damage mode corresponding to the peak frequency. Hilbert-Huang Transform (HHT) of AE signals can clearly illustrate the frequency distribution of Intrinsic Mode Functions (IMF) components in time-scale in different damage stages, and can calculate accurate instantaneous frequency for damage modes recognition to help understanding the damage process.

  2. The velocity measurement of Se mode in the transient signals of lamb wave and determination of the Young's modulus in unidirectional and bidirectional CFRP plates

    International Nuclear Information System (INIS)

    Lamb waves were generated by breaking pencil leads on the surface and edge of unidirectional and (0 degree/90 degree) bidirectional carbon fibre reinforced plastic(CFRP) plates. The transient signals of Lamb waves were detected with two broad band piezoelectric transducers of 6.35 mm diameter with 10 MHz center frequency. The fundamental symmetric mode was identified by the power spectrum analysis and the group velocities of these modes were obtained by measuring the delay time of the signals received by two transducers placed at different positions. Young's moduli, determined with the group velocities of the fundamental symmetric mode, are 9.1 GPa and 120 GPa normal and along the fibre direction respectively in unidirectional CFRP plate. And those along the two fibre directions in [0 degree/90 degree]12s bidirectional CFRP plates are 64.8 GPa and 63.7 GPa, respectively.

  3. Fatiga en CFRP: Caracterización y Método Óptico para la Estimación del Daño

    OpenAIRE

    Zuluaga Ramírez, Pablo

    2015-01-01

    El desarrollo de nuevas estructuras aeroespaciales optimizadas, utilizan materiales compuestos, para los componentes críticos y subsistemas, principalmente polímeros reforzados con fibra de carbono (CFRP). Un conocimiento profundo del estado de daño por fatiga de estructuras de CFRP avanzado, es esencial para predecir la vida residual y optimizar los intervalos de inspección estructural, reparaciones y/o sustitución de componentes. Las técnicas actuales se basan principalmente en la medición ...

  4. CFRP platform and hexapod mount for the Array of MIcrowave Background Anisotropy (AMiBA)

    Science.gov (United States)

    Raffin, Philippe A.; Martin, Robert N.; Huang, Yau-De; Patt, Ferdinand; Romeo, Robert C.; Chen, Ming-Tang; Kingsley, Jeffrey S.

    2004-09-01

    AMiBA consists of a 90 GHz interferometric array telescope with dishes ranging in size from 0.3 to 2.4 meter in diameter, mounted on a 6-meter fully steerable platform. The dishes are attached to the receivers, which are mounted on a platform controlled by a six degree of freedom hexapod mount. The hexapod mount is a parallel connection manipulator also called Stewart Platform. The basic reference for this mechanism is a paper by Stewart. The Stewart Platform is a unique kinematically constrained work platform. It can be manipulated through the six degrees of freedom. The hexapod also provides better accuracy, rigidity, load to weight ratio and load distribution than a serial manipulator or traditional manipulator. The advantages of the hexapod shows that it is a great choice for the AMiBA project. Vertex Antennentechnik GmbH fabricates the hexapod. Testing has started in Germany. The telescope will be delivered in the summer of 2004. The 6m in diameter hexagonal platform is made of carbon fiber reinforced plastics (CFRP) and consists of seven pieces of three different unique types. The platform can be disassembled and fits in a container for transportation. The mounting plane flatness is an important issue for the platform assembly. The deflection angle of the mounting plane relative to any other mounting position must be less than 20 arcsec. Meanwhile, the platform must endure a loading of 3 tons. The platform has been built by Composite Mirror Applications, Inc. (CMA) in Tucson, and mounted on the Hexapod in Germany. This report describes the design and testing of platform and mount for the AMiBA telescope.

  5. Finite Element Analysis for Fatigue Damage Reduction in Metallic Riveted Bridges Using Pre-Stressed CFRP Plates

    Directory of Open Access Journals (Sweden)

    Elyas Ghafoori

    2014-04-01

    Full Text Available Many old riveted steel bridges remain operational and require retrofit to accommodate ever increasing demands. Complicating retrofit efforts, riveted steel bridges are often considered historical structures where structural modifications that affect the original construction are to be avoided. The presence of rivets along with preservation requirements often prevent the use of traditional retrofit methods, such as bonding of fiber reinforced composites, or the addition of supplementary steel elements. In this paper, an un-bonded post-tensioning retrofit method is numerically investigated using existing railway riveted bridge geometry in Switzerland. The finite element (FE model consists of a global dynamic model for the whole bridge and a more refined sub-model for a riveted joint. The FE model results include dynamic effects from axle loads and are compared with field measurements. Pre-stressed un-bonded carbon fiber reinforced plastic (CFRP plates will be considered for the strengthening elements. Fatigue critical regions of the bridge are identified, and the effects of the un-bonded post-tensioning method with different pre-stress levels on fatigue susceptibility are explored. With an applied 40% CFRP pre-stress, fatigue damage reductions of more than 87% and 85% are achieved at the longitudinal-to-cross beam connections and cross-beam bottom flanges, respectively.

  6. Fatigue and post-fatigue performance of Fabry-Perot FOS installed on CFRP-strengthened RC-beams

    Science.gov (United States)

    Gheorghiu, Catalin; Labossiere, Pierre; Proulx, Jean

    2004-07-01

    There is a growing need for built-in monitoring systems for civil engineering infrastructures, due to problems such as increasing traffic loads and rising costs of maintenance and repair. Fibre optic sensors (FOS), capable of reading various parameters are promising candidates for life-long health monitoring of these structures. However, since FOS have only been introduced recently into the field of structural monitoring, their acceptance and widespread implementation will be conditioned by their durability under severe climatic and loading conditions. This paper reports on the performance of strain extrinsic FOS attached to carbon fibre reinforced polymer (CFRP) plates used to strengthen concrete structures. The specimens tested in this project are reinforced concrete (RC) beams with an additional external CFRP reinforcement. The FOS-instrumented beams were first subjected to fatigue loading for various numbers of cycles and load amplitudes. Then, they were tested monotonically to failure under four-point-bending. The test results provide an insight on the fatigue and post-fatigue behaviour of FOS used for monitoring reinforced concrete structures.

  7. Study on the Shear Strength Calculation of Masonry Walls Strengthened with CFRP%粘贴CFRP砖砌体墙受剪承载力计算方法

    Institute of Scientific and Technical Information of China (English)

    左宏亮; 郭亮; 樊越

    2013-01-01

    The purpose of this paper is to propose the calculation formula of coefficients of exertion for CFRP strain and the applicable conditions in brick masonry walls strengthened with CFRP under low cyclic loading. Combining with the authors'experience and related references, experimental data of 4 groups of brick masonry walls strengthened with CFRP with different height-width ratio under low cyclic loading are analyzed,coefficients of exertion for CFRP strain and the measured value of shear capacity provided by CFRP are obtained. Then the relationship between coefficients of exertion for CFRP strain and height-width ratio is studied, the calculation formula of coefficients of exertion for CFRP strain is proposed and the consistency between the measured value and the theoretical value is checked. The results show that there is an approximate linear relationship between coefficients of exertion for CFRP strain and height-width ratio when the height-width ratio of a brick masonry walls is between 0. 56 and 0. 71 and the calculation formula is α = 0. 923 -0. 85 8 A ,The average ratios of the measured value of shear capacity provided by CFRP to the theo-retical value is 1. 07, standard deviation is 0. 33 and variation coefficient is 0. 31. The conclusions show that when the height-width ratio of brick masonry walls is between 0. 56 and 0. 71, the calculation formula of coefficients of exertion for CFRP strain can accurately figure out the value of the shear capacity provided by CFRP and has certain guidance in the field of seismic strengthening design of masonry walls in actual engineering. When σy/fm <0. 32 and the stickup method of CFRP could not effectively inhibit the emergence of horizontal cracks,or 0. 67≤σy/fm < 1. 0,the increasing shear capacity provided by CFRP should be ignored. As for the brick masonry wall which is strengthened with a large amount of CFRP,the pattern of diagonal compression failure should be discriminated..%目的 研究粘贴CFRP砖砌

  8. Enhanced FBG sensor-based system performance assessment for monitoring strain along a prestressed CFRP rod in structural monitoring

    DEFF Research Database (Denmark)

    Kerrouche, A.; Boyle, W.J.O.; Sun, T.; Grattan, K.T.V.; Schmidt, Jacob Wittrup; Täljsten, Björn

    2009-01-01

    be converted to a conventional electronic signal. This procedure provides the means for the FBG-based sensor system to be used for several monitoring applications. The aim of this research is to improve an existing monitoring system which has been used for several Held test inspections. A brief...... description of the existing FBG-based system and the evaluation of the software developed to be compatible with a resolution reaching as high as +/- 0.15 mu epsilon is presented. The system has been tested under particular conditions where a prestressed CFRP (carbon fiber reinforced polymer) rod to which a...... FBG sensor is attached is used. The test procedure and results obtained are discussed in some detail. Crown...

  9. Effect of plasma surface treatment of recycled carbon fiber on carbon fiber-reinforced plastics (CFRP) interfacial properties

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hooseok, E-mail: hooseok.lee@gmail.com; Ohsawa, Isamu; Takahashi, Jun

    2015-02-15

    Highlights: • Plasma treatment was used to improve the adhesion property between the recycled CF and polymer matrix. • In order to evaluate the adhesion between plasma treated recycled CF and polymer, micro droplet test was conducted. • The interfacial shear strength and the interfacial adhesion of recycled carbon fiber increased. - Abstract: We studied the effects of plasma surface treatment of recycled carbon fiber on adhesion of the fiber to polymers after various treatment times. Conventional surface treatment methods have been attempted for recycled carbon fiber, but most require very long processing times, which may increase cost. Hence, in this study, plasma processing was performed for 0.5 s or less. Surface functionalization was quantified by X-ray photoelectron spectroscopy. O/C increased from approximately 11% to 25%. The micro-droplet test of adhesion properties and the mechanical properties of CFRP were also investigated.

  10. Effect of plasma surface treatment of recycled carbon fiber on carbon fiber-reinforced plastics (CFRP) interfacial properties

    International Nuclear Information System (INIS)

    Highlights: • Plasma treatment was used to improve the adhesion property between the recycled CF and polymer matrix. • In order to evaluate the adhesion between plasma treated recycled CF and polymer, micro droplet test was conducted. • The interfacial shear strength and the interfacial adhesion of recycled carbon fiber increased. - Abstract: We studied the effects of plasma surface treatment of recycled carbon fiber on adhesion of the fiber to polymers after various treatment times. Conventional surface treatment methods have been attempted for recycled carbon fiber, but most require very long processing times, which may increase cost. Hence, in this study, plasma processing was performed for 0.5 s or less. Surface functionalization was quantified by X-ray photoelectron spectroscopy. O/C increased from approximately 11% to 25%. The micro-droplet test of adhesion properties and the mechanical properties of CFRP were also investigated

  11. Experiment on Anchorage Performance of Bond-type Anchorage for CFRP Tendon%CFRP筋粘结式锚具锚固性能试验

    Institute of Scientific and Technical Information of China (English)

    蒋田勇; 方志

    2011-01-01

    针对碳纤维增强塑料(CFRP)作为预应力筋或拉索时出现的锚固问题,开发了一种以活性粉末混凝土(RPC)作为粘结介质的粘结式锚具.建立了平均粘结强度及其对应的滑移量、临界锚固长度以及粘结滑移本构模型等计算公式.通过静载试验研究了筋材表面形状、锚固长度、根数、间距、套筒内壁倾角以及筋材预张拉等对锚固性能的影响.结果表明:CFRP筋的表面形状对以RPC作为粘结介质的粘结式锚具的锚固性能有着决定性影响;当表面压纹CFRP筋的抗拉强度不大于3 000 MPa,RPC抗压强度不小于130 MPa时,对于普通粘结试件,临界锚团长度为20倍筋材直径;对于预张拉粘结试件,当预张比为56%时,锚固系统具有最短的临界锚固长度为13倍筋材直径;多筋同时锚固时,其间距不宜小于1倍筋材直径.%Aimed at anchorage problems that carbon fiber reinforced polymer/plastics (CFRP)was used as prestress tendon and cable reactive powder concrete (RPC) was regarded as bond medium and based on it, a new bond-type anchorage was developed.The calculated formulas of average bond strength and its corresponding slip, critical anchorage length, and bond-slip constitutive model were proposed.Influences of surface shape, bond length, number and space of CFRP tendons, slope angle of inner wall of steel sleeve and pretensioning load on anchorage performance were studied by static test.Test results show that the surface shape of CFRP tendon is significant to the anchorage performance of the bond-type anchorage.When the tensile strength of the indented surface CFRP tendon is less than 3 000 MPa and compressive strength of RPC is more than 130 MPa, the critical anchorage length is 20 diameters of general CFRP tendon for common bond specimen, the shortest critical anchorage length in anchorage system is 13 diameters of pretensioning CFRP tendon with ratio of 56 % of pretensioning load.The appropriate rod space is

  12. Prospects and limitations of digital Shearography and Active Thermography in finding and rating flaws in CFRP sandwich parts with honeycomb core

    Science.gov (United States)

    Gruber, J.; Mayr, G.; Hendorfer, G.

    2012-05-01

    This work shows the prospects and limitations of the non-destructive testing methods Digital Shearography and Active Thermography when applied to CFRP sandwich parts with honeycomb cores. Two specimens with different core materials (aluminum, NOMEX) and artificial flaws such as delaminations, disbonds and inclusions of foreign material, are tested with Digital Shearography and Pulse Thermography including Pulse Phase Thermography. Both methods provide a good ability for finding and rating the flaws.

  13. Finite element simulation of 0°/90° CFRP laminated plates subjected to crushing using a free-face-crushing concept

    OpenAIRE

    Israr, Haris Ahmad; Rivallant, Samuel; Bouvet, Christophe; Barrau, Jean-Jacques

    2014-01-01

    International audience This paper describes the development of a numerical model of (0°/90°) CFRP plates subjected to low velocity crushing, based on physical observations. The developed model is represented at the meso-scale and is based on five main ideas: 1 - meshing of each ply of the laminate; 2 - use of cohesive elements to represent delamination and plies splaying; 3 - simulation of macro-scale fragments; 4 - representation of the localized crushing of plies at their extremities wit...

  14. Performance of externally CFRP confined RC columns with changes in thickness of the wrap, slenderness of the column and shape of the section

    OpenAIRE

    Gahmous M.; Benzaid R.; Chikh N.; Mesbah H.

    2012-01-01

    The present study deals with the analysis of experimental results, in terms of load carrying capacity and strains, obtained from tests on reinforced concrete (RC) columns, strengthened with external carbon fiber reinforced polymer (CFRP) sheets. The experimental parameters include: number of wrap layers, slenderness of the columns (L/a or L/D) and shape of the section (circular and square). A total of 48 specimens were subjected to axial compression. All test specimens were loaded to failure ...

  15. Simultaneous Measurement of Thermal Diffusivity and Thermal Conductivity by Means of Inverse Solution for One-Dimensional Heat Conduction (Anisotropic Thermal Properties of CFRP for FCEV)

    Science.gov (United States)

    Kosaka, Masataka; Monde, Masanori

    2015-11-01

    For safe and fast fueling of hydrogen in a fuel cell electric vehicle at hydrogen fueling stations, an understanding of the heat transferred from the gas into the tank wall (carbon fiber reinforced plastic (CFRP) material) during hydrogen fueling is necessary. Its thermal properties are needed in estimating heat loss accurately during hydrogen fueling. The CFRP has anisotropic thermal properties, because it consists of an adhesive agent and layers of the CFRP which is wound with a carbon fiber. In this paper, the thermal diffusivity and thermal conductivity of the tank wall material were measured by an inverse solution for one-dimensional unsteady heat conduction. As a result, the thermal diffusivity and thermal conductivity were 2.09 × 10^{-6}{ m}2{\\cdot }{s}^{-1} and 3.06{ W}{\\cdot }{m}{\\cdot }^{-1}{K}^{-1} for the axial direction, while they were 6.03 × 10^{-7} {m}2{\\cdot }{s}^{-1} and 0.93 {W}{\\cdot }{m}^{-1}{\\cdot }{K}^{-1} for the radial direction. The thermal conductivity for the axial direction was about three times higher than that for the radial direction. The thermal diffusivity shows the same trend in both directions because the thermal capacity, ρ c, is independent of direction, where ρ is the density and c is the heat capacity.

  16. NC Machining Method for CFRP Window of Cylindrical Module%碳纤维复合材料柱型舱段窗口数控加工方法

    Institute of Scientific and Technical Information of China (English)

    孙艳杰; 董波; 蒋文革; 李兰柱; 丁江民

    2011-01-01

    使用碳纤维复合材料构件数控高速钻磨机床,对T300/AG80碳纤维复合材料柱型舱段构件方形窗口特征数控加工方法进行了研究.根据结构件材料特性和形状特点,得出了主轴转速6 000~18 000r/min、进给速率5~25 mm/min适用于柱型舱段方形窗口数控加工的优化参数和程序,实现了碳纤维复合材料柱型舱段窗口的数控加工.%This article studies the CNC machining methods of square window of T300/AG80 carbon fiber cylindrical composite, with the high-speed drilling and grinding CNC machine tools for carbon fiber reinforced plastics.According to structure and characteristics of the material properties, optimized process parameters and CNC programs for processing the square cylindrical module are obtained with spindle speed of 6 000 to 18 000 r/min and feed rate of 5 to 25 mm/min , which makes the realization of the automatic processing of the columnar module window of CFRP.

  17. Comparison of PZT and FBG sensing technologies for debonding detection on reinforced concrete beams strengthened with external CFRP strips subjected to bending loads

    Directory of Open Access Journals (Sweden)

    Sevillano, E.

    2016-06-01

    Full Text Available The development of monitoring technologies particularly suitable to be used with novel CFRP strengthening techniques has gained great attention in recent years. However, in spite of the high performance of these advanced composite materials in the strengthening and repairing of structures in service, they are usually associated with brittle and sudden failure mainly caused by debonding phenomena, originated either at the CFRP-plate end or at the intermediate areas in the vicinity of flexural cracks in the RC beam. Thus, it is highly recommended for these structures to be monitored in order to ensure their integrity while in service. Specifically, the feasibility of smart sensing technologies such as Fiber Bragg Grating (FBG sensors and piezo-impedance transducers (PZT has been studied. To the knowledge of the authors, none serious study has been carried out until now concerned to the topic of damage detection due to debonding in rehabilitated structures with CFRP composites.El desarrollo de tecnologías de monitorización aplicables junto con las novedosas técnicas de refuerzo basadas en materiales CFRP ha recibido una atención creciente los últimos años. Sin embargo, a pesar del alto rendimiento de estos avanzados materiales compuestos en la reparación y refuerzo de estructuras en servicio, están habitualmente asociados a fallos frágiles y repentinos causados principalmente por fenómenos de despegue, originados bien en los extremos del refuerzo, bien en áreas intermedias en las proximidades de grietas de flexión existentes en la viga. Por tanto, es altamente recomendable monitorizar estas soluciones estructurales de cara a garantizar su integridad en servicio. Específicamente, se ha estudiado la viabilidad de sensores inteligentes tales como los sensores Fiber Bragg Grating (FBG o los transductores piezoeléctricos (PZT. Hasta donde los autores saben, no se han realizado estudios serios hasta la fecha abordando la detección de da

  18. RELIABILITY ANALYSIS OF RC CONCRETE BEAMS STRENGTHENED WITH NSM CFRP TENDONS%内嵌碳纤维筋加固钢筋混凝土梁可靠性研究

    Institute of Scientific and Technical Information of China (English)

    丁亚红; 郝慧敏

    2012-01-01

    Based on the flexural experimental research on RC concrete beams strengthened with NSM CFRP tendons, the reliability index before and after reinforced concrete beams strengthened with the amount of CFRP tendons was studied. The reliability analysis of different amount of RC concrete beams strengthened with NSM CFRP tendons was discussed. The results showed that the reliability index could be enhanced maximally by 79. 52% , which not only made full use of the intensity of the CFRP tendons, but also improved observably the reliability of the reinforced beams. The reinforcement effect with two NSM CFRP tendons was better than the others.%基于内嵌碳纤维(简称CFRP)筋抗弯加固混凝土梁的试验研究,开展变加固量内嵌CFRP筋加固梁可靠指标计算分析,探讨内嵌CFRP筋加固钢筋混凝土梁的可靠度水平随加固量的变化情况。结果表明:内嵌CFRP筋加固梁能够充分利用CFRP的高强特点,明显提高被加固梁的可靠性,其可靠指标提高幅度最大为79.52%。综合各方面因素分析可知,内嵌2根CFRP筋的加固效果最好。

  19. Análisis de métodos para evaluar el refuerzo a esfuerzo cortante con CFRP en vigas de hormigón armado

    OpenAIRE

    Valcuende Payá, Manuel Octavio; Parra, C; Martínez-Conesa, E.; Garrido, A.

    2012-01-01

    [ES] En este trabajo de investigación se comparan diferentes modelos de cálculo de refuerzo a esfuerzo cortante mediante polímeros reforzados con fibras de carbono (CFRP) clasificados según el modo de fallo. En el diseño del refuerzo se tiene en cuenta la modificación del comportamiento de la viga por el refuerzo. Los estudios muestran que siempre que sea posible, la dirección principal de las fibras debe ser perpendicular a las fisuras de cortante. La contribu...

  20. Effects of homogeneous low energy electron beam irradiation (HLEBI) on adhesive force of peeling of carbon fiber reinforced epoxy polymer (CFRP) and polytetrafluoroethylene (PTFE)

    International Nuclear Information System (INIS)

    The effects of homogeneous low energy (170 keV) electron beam irradiation (HLEBI) on the adhesion force indicated by peeling resistance (oFp) at each accumulative probability of peeling resistance (Pp) of laminated sheets of carbon fiber reinforced epoxy polymer (CFRP) and polytetrafluoroethylene (PTFE) were investigated. The slight detectable adhesive force of oFp before treatment were 0.3 and 7.6 Nm−1 at low and mid Pp of 0.06 and 0.50, respectively, since the intermolecular attractive force exists at PTFE and epoxy polymers at cross-linking zone. Although additional dose of HLEBI apparently reduced the oFp of laminated sheets irradiated at more than 0.30 MGy as usual radiation damages, small dose of 0.04 to 0.22 MGy-HLEBI increased the adhesive force of peeling (oFp) substantially over the untreated. 0.13 MGy-HLEBI enhanced the oFp up to the largest values of 9.8 and 44.0 Nm−1, respectively, which were more than 30.5 and 5.8 times larger than those before treatment. Based on the 3-parameter Weibull equation, the statistically lowest oFp value at Pp = 0 (Fs) was increased from zero to 9.2 Nm−1 by applying the 0.13 MGy HLEBI. XPS (X-ray photoelectron spectrometry) measurements detected the fluorine (1s) signal on peeled surface of CFRP side indicating the residual PTFE adhered well to the epoxy of CFRP by the HLEBI. Thus, the fracture probably propagated through the PTFE inside near cross-linking zone of interface. This is probably a result of adhesion force of PTFE/CFRP being made stronger than the cohesive force of epoxy polymer. When HLEBI cut the chemical bonds and generated active terminated atoms with dangling bonds of Epoxy and PTFE polymers in cross-linking zone with chemical bonding around adhesive interface, strengthening the adhesive force indicated by oFp was mainly induced by the chemical bonding, as well as intermolecular attractive force in cross-linking polymers. (author)

  1. CFRP筋复合型锚具锚固性能研究%Research on Anchorage Performance of Wedge-bond Anchorage for CFRP Tendons

    Institute of Scientific and Technical Information of China (English)

    刘荣桂; 刘德鑫; 延永东

    2013-01-01

    In order to solve the anchorage problems for carbon fiber reinforced polymer (CFRP) tendons,a wedge-bond anchorage for CFRP tendons was developed.This anchorage consisted of bonding material,metal sleeve,clip and conical barrel.Influence factors of anchorage performance,such as length of clip,length of metal sleeve,clip clamping position and bonding material were illustrated.Results show that bonding material,length of metal sleeve,and clip clamping position will have significant influence on anchorage performance.The clip clamping position should be avoided at both ends of the metal sleeve,and should make compression zone metal sleeve length be less than that of the tension zone length.Meanwhile,the anchorage performance of bonding material Lica-B is better than that of bonding material Lica-A.The each component of wedge-bond anchorage has good cooperative work performance,and there is no relative slip between clip and metal sleeve.The wedge-bond anchorage with reasonable parameters can anchor CFRP tendons with diameter of 8 mm effectively.%为解决碳纤维增强复合材料(CFRP)筋的锚固问题,研制了由粘结材料、金属筒、夹片和锚环组成的CFRP筋复合型锚具,并进行了夹片长度、金属筒长度、夹片夹持位置以及粘结材料对CFRP筋复合型锚具的锚固性能影响试验.结果表明:粘结材料、金属筒长度和夹片夹持位置均对锚固性能有较大影响;夹片的夹持位置应避免在金属筒两端,且宜使金属筒受压区长度小于受拉区长度;Lica-B型粘结材料锚固性能优于Lica-A型粘结材料;复合型锚具各组件协同工作性能良好,夹片与金属筒间无滑移产生;参数合理的该类复合型锚具可有效锚固直径为8 mm的CFRP筋.

  2. Programming

    International Nuclear Information System (INIS)

    The programmer's task is often taken to be the construction of algorithms, expressed in hierarchical structures of procedures: this view underlies the majority of traditional programming languages, such as Fortran. A different view is appropriate to a wide class of problem, perhaps including some problems in High Energy Physics. The programmer's task is regarded as having three main stages: first, an explicit model is constructed of the reality with which the program is concerned; second, this model is elaborated to produce the required program outputs; third, the resulting program is transformed to run efficiently in the execution environment. The first two stages deal in network structures of sequential processes; only the third is concerned with procedure hierarchies. (orig.)

  3. CFRP加固受损桥墩的抗震性能试验研究%Experimental Research on Seismic Performance of Strengthening Damaged Bridge Pier with CFRP

    Institute of Scientific and Technical Information of China (English)

    吴刚; 丁明波

    2013-01-01

    以某城市立交工程为背景,建立桥墩缩尺模型,完成CFRP加固前后模型墩的拟静力破坏试验,分析研究模型墩加固前后的滞回曲线、骨架曲线、刚度退化曲线和能力耗散系数曲线.研究表明,采用CFRP加固受损桥墩,可有效恢复桥墩抗震性能,甚至得到提高,加固效果明显.%The experimental research is based on an interchange engineering of a city, where two scale models of bridge pier are built. Pseudo-static test is conducted to damage the scale model and strengthened the model with CFRP. The hysteretic curve, skeleton curve, stiffness degradation curve and energy dissipation coefficient curve of the scale model and strengthened model are analyzed. The experimental research shows that the seismic performance of bridge pier model can be recovered under the CFRP strengthening technology, and the capacity even can be enhanced The strengthening effect is obvious.

  4. CFRP预应力筋粘结式锚固系统的抗疲劳性能%Fatigue Behavior of Bond-type Anchorage with CFRP Tendon

    Institute of Scientific and Technical Information of China (English)

    方志; 龚畅; 杨剑; 孙志刚

    2012-01-01

    CFRP预应力筋锚固系统的系统研究成果尤其是疲劳性能研究仍较少,采用疲劳试验机对以高性能活性粉末混凝土RPC作为新型粘结介质的CFRP预应力筋粘结式锚具的疲劳性能进行试验研究,CFRP预应力筋锚固系统疲劳试验采取对组装件交替施加静荷载和疲劳荷载,即用静载试验来检验组装件在经历一定次数重复荷载后的静力性能变化.试验结果表明该类锚具具有良好的抗疲劳性能,随着循环加载次数的增加,组装件之间的相对位置将趋于更加稳定的状态;循环加载过程中CFRP筋抗拉刚度略有降低,疲劳136万次与疲劳前组装件CFRP筋的抗拉刚度比值为93.7%.循环荷载作用下对粘结式锚具组装件有损伤,但当所施加的荷载未超过其极限破断力的40%时,CFRP筋与RPC之间的相对位置将保持比较稳定的状态,此时存在一定损伤的粘结式锚具组装件仍具有较好的承载能力.%The research on the anchorage system for CFRP tendons, especially about the fatigue behavior, is weak. A series of fatigue tests were conducted for the developing a bond-type anchorage system for CFRP tendon characterized with RPC as bond medium by fatigue machine under static load and fatigue load alternatively. Then the static behavior of the anchorage system, which experienced certain cycling loading, was inspected by static load test. The test result shows that (1) the new type of anchorage system has good fatigue behavior, with the increasing of cycling load times, the relative position of the parts of anchorage system at more stable status; (2) the tensile stiffness of CFRP tendons be slightly lower in loading process, after 136 million fatigue tests, it is 93.7% of that before fatigue test; (3) harm of anchorage system will occur under cyclic loading, however the relative slip is smaller between CFRP tendon and RPC under less than 40% of ultimate load, and the higher bearing capacity of harmed

  5. Experiment Analysis and Calculation on Ductility Behaviors of High-strength RC Square Columns Strengthened with CFRP%CFRP加固高强混凝土方柱的延性性能试验分析与计算

    Institute of Scientific and Technical Information of China (English)

    王苏岩; 余文华; 曹怀超; 刘毅

    2012-01-01

    To investigate the seismic behaviors of high-strength reinforced concrete (RC) square columns strengthened with carbon fiber reinforced polymer (CFRP), the low cyclic loading test of thirteen high-strength RC square columns was conducted. The seismic behaviors of columns, such as failure patterns, hysteresis behaviors, skeleton curves, energy dissipation capacity and ductility were studied, and the influences of axial load ratio, shear span ratio and CFRP strengthening volume on the ductility of high-strength RC square columns were discussed. The calculation formulae of CFRP effective constraint coefficient and displacement ductility coefficient were proposed. Results show that the ductility and energy dissipation capacity can be significantly reduced as the increase of axial load ratios or the decrease of shear span ratios; CFRP can observably improve the ductility and energy dissipation capacity of high-strength RC square columns; compared with the columns without CFRP, the seismic behaviors of columns with high axial load ratio or low shear span ratio are improved more obviously after being strengthened with CFRP in transverse) and the ductility, energy dissipation capacity increase with the increases of strengthening volume, but the improvement extent reduces gradually.%为了研究碳纤维增强复合材料(CFRP)加固高强混凝土方柱的抗震性能,对13个高强混凝土方柱进行低周反复荷载试验,研究了试件破坏形态、滞回特性、骨架曲线、耗能能力和延性等抗震性能,探讨了轴压比、剪跨比、CFRP加固量对高强混凝土方柱延性性能的影响,给出了计算CFRP布有效约束系数和位移延性系数的公式.结果表明:随着轴压比增大、剪跨比减小,试件耗能能力和延性降低;横向包裹CFRP布可以显著改善高强混凝土方柱耗能能力和延性;与未加固试件相比,横向包裹CFRP布对轴压比较大或剪跨比较小试件的延性提高效果更为显著;随着

  6. Experimental Research and Fnite Element Analysis on Steel Bridge Deck in CFRP Reinforced SFRC Pavements%CFRP 增强钢纤维混凝土钢桥面铺装力学性能试验与数值模拟

    Institute of Scientific and Technical Information of China (English)

    徐欣; 方海; 徐超; 刘伟庆; 庄勇

    2015-01-01

    由于我国日益增加的交通量,很多正交异性钢桥面铺装和正交异性钢板在服役期内都出现了很多病害。碳纤维(CFRP)具有轻质、高强、耐腐蚀等优越性,钢纤维混凝土具有沥青混凝土没有的刚度和普通混凝土没有的抗裂性能。对于将这两种材料用于钢桥面铺装中形成的组合桥面板,取涡河大桥主桥钢箱梁的一段正交异性钢板,分别对“无铺装”,“沥青混凝土铺装”,“钢纤维混凝土铺装”3种模型进行有限元模拟,比较正交异性钢板的应力、挠度、铺装层的纵向拉应力和横向拉应力,找出最不利荷载工况及变化规律。通过计算比较“沥青混凝土铺装”、“钢纤维混凝土铺装”和“CFRP -钢纤维混凝土铺装”3种铺装层的纵向和横向拉应力,得出 CFRP 网格筋对铺装层表面拉应力的控制作用。结果表明低弹模铺装时横向拉应力为控制应力,而高弹模铺装时纵向拉应力为控制应力,正交异性钢板应力最大部位发生在横隔板开孔附近,碳纤维网格筋可以有效地降低铺装面层的横向和纵向拉应力。%Most orthotropic steel deck pavements and orthotropic steel plates appeared many seri-ous diseases in the service period because of the increasing traffic in our country.Carbon Fibre Reinforced Polymer(CFRP)has the superiority of light weight,high strength,corrosion resistance and so on.The stiff-ness of bitulith concrete is small and normal concrete crack resistance is poor.But the steel fiber rein-forced concrete has great stiffness and good crack resistance.This paper proposed a new composite deck combined with CFRP and SFRC.An orthotropic plate of Guohe Bridge is calculated as a case.The Stress and deflection of Orthotropic steel plate,the longitudinal tensile stress and transverse tensile stress of pavement have been calculated in three models,including “without pavement”,“with bitumen

  7. Coda wave interferometry for the measurement of thermally induced ultrasonic velocity variations in CFRP laminates

    Science.gov (United States)

    Livings, Richard; Dayal, Vinay; Barnard, Dan

    2016-02-01

    Ultrasonic velocity measurement is a well-established method to measure properties and estimate strength as well as detect and locate damage. Determination of accurate and repeatable ultrasonic wave velocities can be difficult due to the influence of environmental and experimental factors. Diffuse fields created by a multiple scattering environment have been shown to be sensitive to homogeneous strain fields such as those caused by temperature variations, and Coda Wave Interferometry has been used to measure the thermally induced ultrasonic velocity variation in concrete, aluminum, and the Earth's crust. In this work, we analyzed the influence of several parameters of the experimental configuration on the measurement of thermally induced ultrasonic velocity variations in a carbon-fiber reinforced polymer plate. Coda Wave Interferometry was used to determine the relative velocity change between a baseline signal taken at room temperature and the signal taken at various temperatures. The influence of several parameters of the experimental configuration, such as the material type, the receiver aperture size, and fiber orientation on the results of the processing algorithm was evaluated in order to determine the optimal experimental configuration.---This work is supported by the NSF Industry/University Cooperative Research Program of the Center for Nondestructive Evaluation at Iowa State University.

  8. Diagnostic possibilities following implantation of carbon-fibre-reinforced plastic (CFRP) total hip arthroplasty; Moeglichkeiten der bildgebenden Darstellung eines Hueftendoprothesenschaftes aus Kohlenstofffaserverbundwerkstoff (CFK)

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, T.; Reichel, H.; Birke, A.; Hein, W. [Univ. Halle-Wittenberg (Germany). Klinik und Poliklinik fuer Orthopaedie; Alter, C.; Spielmann, R.P. [Univ. Halle-Wittenberg (Germany). Klinik fuer Diagnostische Radiologie

    1998-03-01

    Introduction: There are many problems in the radiological diagnosis of aseptic loosening in total hip arthroplasty. Computed tomography (CT) and magnetic resonance tomography (MRT) are not usable for metallic implants (stainless steel, cobalt alloy, titanium alloy). Material and Methods: From April 1993 to December 1993 15 CFRP non-cemented hip prostheses have been implanted. In a prospective clinical study plane radiographs, CT and MRT have been analysed. Results: Three stems were revised (1 femoral fracture, 1 severe thigh pain, 1 aseptic loosening). CFRP are not visible in plane radiographs. There was a complete (two-third of the cases) or nearly complete (one-third of the cases) small sclerotic interface between the prosthesis and the bone, these were apparent in CT and MRT in stable implant cases and did not have any clinical correlations. Discussion: The small sclerotic interface is quite different in comparison to so called `Reactive lines`. In one case of aseptic loosening there was an interposition of soft tissue between prothesis and bone in MRT and CT. CFRP inaugurates new diagnostic possibilities in aseptic loosening of hip prosthesis and in tumour surgery too. (orig.) [Deutsch] Einleitung: Die Diagnostik der aseptischen Endoprothesenlockerung bereitet mitunter im Routineroentgenbild erhebliche Probleme. Bei den zumeist verwendeten Implantaten (Material: rostfreier Stahl, Titan- oder Kobaltbasislegierungen) sind Magnetresonanztomographie (MRT) und Computertomographie (CT) wegen grenzschichtnaher Artefakte nicht einsetzbar. Material und Methode: Im Rahmen einer klinischen Studie wurden zwischen April 1993 und Dezember 1993 15 Hueftendoprothesenschaefte aus Kohlenstofffaserverbundwerkstoff (CFK) zementfrei implantiert und prospektiv klinisch, radiologisch und mit MRT/CT untersucht. Ergebnisse: Drei Schaefte mussten im Untersuchungszeitraum entfernt werden (1 Femurfraktur, 1 Oberschenkelschmerz, 1 aseptische Lockerung). Radiologisch imponiert die

  9. Effect of grit spacing on hole diameter precision and hole wall roughness of CFRP laminate drilled with brazed diamond core drill%钎焊金刚石套料钻磨粒间距对碳纤维增强树脂基复合材料(CFRP)制孔直径和孔壁粗糙度的影响

    Institute of Scientific and Technical Information of China (English)

    王伟锋; 陈燕; 徐九华; 牟娟

    2012-01-01

    Carbon fiber reinforced plastics ( CFRP) laminate was drilled with brazed diamond core drill under no cooling condition. The effect of grit spacing of diamond on hole diameter precision and hole wall roughness in drilling CFRP at different feed speed was studied. A heat affected simulation model of CFRP hole diameter drilled with brazed diamond core drill was established. The results indicated that expanding factor oi hole diameter decreased with the increase of grit spacing and feed speed, and grit spacing had a relatively larger effect on expanding factor. The surface roughness of hole wall increased with the increase of grit spacing and feed speed. When grit spacing of brazed diamond core drill was 1. 6 mm and feed speed was 150 mm/min, the hole quality of CFRP laminate was perfect.%在无冷却润滑条件下,采用钎焊金刚石套料钻对CFRP层合板进行钻削加工试验,研究了不同进给速度条件下钎焊金刚石套料钻的磨粒间距对CFRP层合板制孔直径精度和孔壁粗糙度的影响,建立了钎焊金刚石套料钻钻削CFRP的温度场仿真模型.研究结果表明:制孔直径的扩孔因子随着磨粒间距和进给速度的增加而减小,磨粒间距对扩孔因子的影响程度较大;孔壁相同位置处的粗糙度随着磨粒间距和进给速度的增加而增加;采用磨粒间距为1.6 mm的80/100金刚石磨粒的套料钻,在进给速度为150mm/min时钻削CFRP层合板制孔效果好.

  10. THE ANALYSIS OF FLEXURAL BEHAVIOR OF CORRODED RC BEAMS STRENGTHENED WITH CFRP UNDER FATIGUE LOADS%碳纤维加固锈蚀混凝土梁短期疲劳性能研究

    Institute of Scientific and Technical Information of China (English)

    葛若东; 梁进修; 王磊

    2012-01-01

    在不同荷载条件下,对8根钢筋混凝土梁进行试验,研究短期疲劳荷载作用下的变形、应力分布以及短期疲劳荷载作用后的力学指标。试验结果和分析表明:疲劳荷载对锈蚀钢筋混凝土梁的影响较大,明显降低试验梁的极限强度和延性;碳纤维加固后的锈蚀混凝土梁的极限承载力明显提高,且在破坏时具有良好的延性,承载力极限值可以提高22%~47%。碳纤维"U"形箍对试验梁的性能影响较大,没有粘贴"U"形箍的碳纤维加固试验梁在后期加载过程中,由于混凝土保护层的突然脱落而发生破坏。采用碳纤维材料加固后的较低锈蚀率的钢筋混凝土梁在经过短期疲劳荷载后依然能够具有良好的力学性能。%Eight RC beams including four CFRP strengthened beams were tested after short-term fatigue. The distortion, stress distribution, ultimate load of corroded reinforced concrete beams were investigated. Both the experimental and analytical results indicated that fatigue loading had a significant impact on the performance of corroded RC beams; It could reduce the ultimate strength and ductility of the beams substantially. The ultimate load- carrying capacity of the CFRP-strengthened corroded beams are enhanced evidently and had a preferable ductility during damage. The loading capacity of RC beams with CFRP strengthened was in creased by 22% to 47%. The U- wrap CFRP sheet had an obvious effect on beams, the potential delamination of the concrete cover following steel corrosion could cause sudden failure of RC beams strengthened with CFRP at later loading stages. Repairing a low corrosion rate beams by CFRP still had good mechanical properties after a short-term fatigue loadings.

  11. KESME YÖNÜNDEN YETERSİZ DİKDÖRTGEN KESİTLİ BETONARME KİRİŞLERİN CFRP İLE GÜÇLENDİRİLEREK KESME KAPASİTELERİNİN ARTTIRILMASI

    OpenAIRE

    Tokgöz, Hanifi; DÜNDAR, Behçet

    2014-01-01

    In this study, reinforcement concrete beam bending due to tensile stress that occur below the surface and cutting stresses occurred L/4 from side surface CFRP textile and strengthen the wound was made. Experimental study, nine pieces of reinforcement concrete beams produced experimental elements. Load-displacement behavior of reinforced concrete beams, ductility capacity and energy consumption were investigated. As insufficient in terms of shear beam shear zones produced 3 x 90° and 45° angle...

  12. Bearing capacity calculation of flexural members strengthened with CFRP%粘贴碳纤维加固受弯构件的抗弯承载力计算

    Institute of Scientific and Technical Information of China (English)

    张章; 吴锋; 周国然

    2015-01-01

    The bearing capacity formula of flexural members strengthened with CFRP and the material strength coefficient are proposed in this paper. Combined with experimental data, we obtained the calculation method to improvement coefficient, which can be used to simply calculate the bearing capacity. The bending capacity test of PHC pipe pile strengthened with CFRP was developed. The test results show that the calculation formula for beams strengthened with CFRP also can be used to calculate the bearing capacity of pipe piles strengthened with CFRP.%首先提出碳纤维加固受弯构件承载力计算公式,并提出碳纤维加固材料强度系数,结合收集到的粘贴碳纤维加固梁承载力试验数据,建立碳纤维加固钢筋混凝土梁的抗弯承载力提高系数计算公式,实现粘贴碳纤维加固梁的简化计算。开展了粘贴碳纤维加固预应力高强度混凝土(PHC)管桩抗弯承载力试验。试验结果表明,提出的碳纤维加固梁承载力计算公式也可用于碳纤维加固混凝土管桩承载力的计算。

  13. Extended Finite Element Analysis on H-Shaped Damage Steel Beam Strengthened with CFRP%CFRP加固H型损伤钢梁的扩展有限元分析

    Institute of Scientific and Technical Information of China (English)

    姜震宇; 王春江; 李向民; 许清风; 张卫海

    2012-01-01

    A finite element model for H-shape steel beams strengthened with CFRP are given out on the basis of extended finite element method(XFEM) which was used in the glue interfacial crack analysis. Experiments of steel beams without crack were used for accuracy verification of the XFEM model and the parameters analysis of the crack model. On this basis of the verifications lots of analysis for the glue interfacial stress of H-shaped steel beam strengthened with CFRP have been done by using the proposed procedure just before. All the computing results were compared by changing the model parameters. The results demonstrate that XFEM model is sufficiently accurate for the analysis of CFRP strengthened H-Shape steel beams with initial crack.The simulation procedure can be carried out without remeshing,and can also describe the crack's debonding path accurately. At last the changing rules of the model's parameters, such as the effective bonding length of the CFRP and the adhesive interfacial stress etc. ,are presented in details.%应用扩展有限元法(Extended Finite Element Method,XFEM)建立了碳纤维增强复合材料(Carbon Fiber Reinforced Polymer,CFRP)加固H型钢梁的有限元模型.用CFRP布加固无损伤H型钢梁试验结果进行了比较分析和胶层损伤开裂模型的参数验证,然后,应用该方法系统分析了CFRP布加固有损伤H型钢梁胶层界面的应力分布和开裂损伤情况,并进行了参数的比较分析.分析结果表明,扩展有限元法在CFRP加固带损伤H型钢梁问题方面具有较好的精度,其避免了网格重剖分的问题,也可以模拟出裂纹扩展的路径.最后,在此模型基础上,研究了CFRP布有效粘结长度和胶层界面应力等参数的变化规律.

  14. Análisis de métodos para evaluar el refuerzo a esfuerzo cortante con CFRP en vigas de hormigón armado

    Directory of Open Access Journals (Sweden)

    Parra, C.

    2012-06-01

    Full Text Available Different models of shear-strengthened calculation by means of Carbon Fiber-Reinforced Polymer (CFRP are compared in this investigation works classified according to the way of failure. We take into account the modification of the behavior of the beam for the reinforcement in its design. The surveys show that as long as it is possible the main direction of the fibers must be perpendicular to the shear crakc. The contribution of the reinforcement to the resistance to shear-strengthened of the beam depends on the steel stirrups in the original beam. When the reinforcement strips thickness increases the resistance to shear-strengthened of the beam also increases. This relation tends to be lineal when the beam is not cracks. At last we must state that both the inclination angle of the crack and the shear-strengthened resisted by the reinforcement depend on the inclination angle of the fiber.

    En este trabajo de investigación se comparan diferentes modelos de cálculo de refuerzo a esfuerzo cortante mediante polímeros reforzados con fibras de carbono (CFRP clasificados según el modo de fallo. En el diseño del refuerzo se tiene en cuenta la modificación del comportamiento de la viga por el refuerzo. Los estudios muestran que siempre que sea posible, la dirección principal de las fibras debe ser perpendicular a las fisuras de cortante. La contribución del refuerzo a la resistencia a cortante de la viga depende de los estribos de acero existentes en la viga original. Cuando aumenta el espesor del refuerzo la resistencia a cortante de la viga se incrementa. Esta relación tiende a ser lineal cuando la viga no está fisurada. Por último indicar que tanto el ángulo de inclinación de las fisuras, como el cortante resistido por el refuerzo, dependen del ángulo de inclinación de las fibras.

  15. Mechanical behavior experiment of wedge-bond anchorage for CFRP-tendons%CFRP筋复合型锚具的受力性能试验

    Institute of Scientific and Technical Information of China (English)

    王军; 李明君; 蔡东升; 刘德鑫

    2012-01-01

    In order to investigate the influence of main design parameters on anchorage performance and internal stress distribution of wedge-bond anchorage for CFRP tendons, five groups of parameter tests on wedge-bond anchorage were designed. The ultimate load, slip deformation of anchor ring and stress of metal sleeve stations were determined. The influence of design parameters on anchorage performance, the tress distribution and variation of metal sleeve were contrastively investigated through static loading testing. The results show that the anchorage performance with metal sleeve thickness of 2 mm, a wedge length of 65 mm, bond length of 500 mm is optimal. The anchor between wedge and metal sleeve is good without relative displacement. The tress distribution and variation of metal sleeve can reflect the internal stress distribution of anchorage, and the perk of stress curve indicates bonding failure between colloid and CFRP tendon near the observation point.%为研究CFRP筋复合型锚具的主要设计参数对锚固性能的影响及锚具内部受力情况,设计了5个复合型锚具的参数静载试验,测量了锚具的极限荷载、锚环-CFRP筋间滑移变形和金属筒测点应变,通过静载试验对比分析了各设计参数对锚固效果的影响,以及金属筒表面应力的分布情况与变化规律.研究结果表明:当金属筒壁厚为2 mm,夹片夹持长度为65 mm,粘结长度为500 mm时,锚具的锚固性能较好;夹片-金属筒间锚固良好,无滑移;金属筒应力分布与变化可反映锚具内部受力情况,测点应力曲线峰值预示该位置附近的胶体与CFRP筋间的粘结破坏.

  16. Experimental study on PVC-CFRP confined reinforced concrete short column under axial compression%PVC-CFRP管钢筋混凝土轴压短柱试验研究

    Institute of Scientific and Technical Information of China (English)

    于峰; 牛荻涛

    2013-01-01

    This paper presents the results of experimental investigations on 10 PVC-CFRP confined reinforced concrete columns.The influences of the hoop spacing of CFRP strips and the axial reinforcement on the load-carrying capacity,deformation and failure mode of PVC-CFRP confined reinforced concrete columns were studied.Test results show that the load-carrying capacity and ultimate compressive strain of axially reinforced members with reinforced ratio 1.8% respectively increase about 24% and 16% compared with those of members without axial reinforcement; the loadcarrying capacity and ultimate compressive strain decrease with the increase of the hoop spacing of CFRP strips; when the axially reinforced members fail,multiple CFRP strips fracture and longitudinal reinforcement buckle at the middle height of the specimens.The stress-strain relationship curves of PVC-CFRP confined reinforced concrete column may be divided into three stages:at the first segment,the stress-strain relationship curves is parabola; at the second segment,the stress-strain relationship exhibits an obvious transition segment ; at the third segment,before the failure of the axially reinforced members,the axial stress and strain is in the increasing state.The slope tangent of the hardening segment of axially reinforced members is larger than that of members without axial reinforcement.Based on the static equilibrium and limit equilibrium,a calculating formula of the bearing capacity of PVC-FRP confined concrete column was derived.The calculated values of the proposed formula agree well with the experimental results.%通过10根PVC-CFRP管钢筋混凝土短柱轴压试验,分析CFRP条带环箍间距和轴向配筋等因素对PVC-CFRP管钢筋混凝土短柱承载力、变形以及破坏形态的影响.试验研究表明:与无筋试件相比,配筋率为1.8%的配筋试件的承载力和轴向极限压应变分别提高约24%和16%;随着CFRP条带环箍间距的增大,配筋试件的承载

  17. 预应力CFRP布加固RC梁抗弯承载力影响参数分析%Grey Relational Analysis of Parameters on Flexural Capacity of Prestressed CFRP Strengthened RC Beams

    Institute of Scientific and Technical Information of China (English)

    郝娟; 吴见丰

    2011-01-01

    采用灰色系统理论的关联分析方法,对已有17组预应力CFRP布加固RC梁的实验数据进行关联度计算,分析碳纤维布配布量、梁截面高度、钢筋配筋率、预应力度、混凝土强度和碳纤维布抗拉强度等参数对加固梁抗弯承载力的影响。结果表明,上述影响参数对加固梁的抗弯承载力影响程度依次递减。本文构建了一个考虑影响参数组合权系数的预应力CFRP布加固RC梁抗弯承载力计算模型,并回归出系数向量,公式计算值与试验值吻合良好。%Based on 17 groups of test data on flexural capacity of prestressed carbon fiber reinforced plastics(CFRP) strengthened RC beams,the technique of analyzing the influence parameters on flexural capacity using grey relational method is presented in this paper.The influence parameters include CFRP amount,beam height,reinforcement ratio,prestressing degree of CFRP,concrete strength and fiber tensile strength.The results of grey relational analysis indicate the influential order of above parameters is gradually decreased.Considering coefficients of combination weight,a model to predict the flexural capacity of prestressed CFRP strengthened RC beams is established and the coefficient vectors are obtained by regression.The calculated results agree well with the experimental results.

  18. 碳纤维布加固火灾后钢筋混凝土梁的试验研究%Experimental investigation on RC beams strengthened with CFRP after fire damage

    Institute of Scientific and Technical Information of China (English)

    王红亚; 陈礼刚; 孙羽

    2011-01-01

    Experiment of three full-scale RC (Reinforced Concrete) beams going through high temperature is presented. And experiment of two beams strengthened by CFRP ( carbon fiber reinforced polymer) and one common beam for comparison is test to observe and compare the whole failure process. The results are analyzed. It is found that RC beams strengthened with CFRP can considerably increase the ultimate strength and the stiffness after the steel has yielded and it can limit the further development of the cracks of beams. So,for strengthening RC beams after fire damage with CFRP is an available method.%首先简要介绍了3根足尺的钢筋混凝土梁火灾试验情况,火灾后用碳纤维布加固其中两根梁,然后对加固后的梁和1根未加固的对比梁进行单调加载的静载试验,观测比较梁发生破坏的全过程.通过对静载试验结果进行分析发现,碳纤维布加固能够明显提高火灾后钢筋混凝土梁的极限承载力和钢筋屈服后的刚度,能够较好约束梁裂缝的发展.因此,碳纤维布对于火灾损伤后的钢筋混凝土梁,是一种较为有效的加固方法.

  19. Study on Deflection of RC Beams Strengthened with Prestressed CFRP%预应力碳纤维布加固钢筋混凝土梁挠度研究

    Institute of Scientific and Technical Information of China (English)

    余琼; 张燕语

    2011-01-01

    The stiffness of RC beams strengthened with prestressed CFRP sheets can be improved effectively,and the deflection of the strengthened beams will correspondingly decrease as the prestress level rises. This paper analyzes the change of flexural stiffness of RC beams strengthened with prestressed CFRP, and the effects of prestressing force on the stiffness of strengthened beams. Thus the changing progress of the loaddeflection curves is analyzed, and the deflection curve is approximately regarded as composed by three straight lines. On the basis of the straight-line bilinear method, the formula for calculating the deflection of strengthened reinforced beams using CFRP is proposed, and its results are compared with the experimental results of two experiments ( including 10 specimens). The result shows that the formula proposed in the paper coincides with the results of the experiment.%预应力碳纤维布加固钢筋混凝土梁可以有效地提高构件的抗弯刚度,并且随着预应力水平的提高,加固梁的挠度相应地减小.分析了预应力碳纤维布加固混凝土梁的抗弯刚度变化过程,及预应力对加固梁刚度的影响.由此分析了加固梁的荷载-挠度曲线的变化过程,将挠度曲线近似看作由三段直线组成,在直线双线性法的基础上提出了加固梁的挠度计算公式,按公式计算的值与两个试验(共10根试件)结果较为吻合.

  20. Behaviors of super-long span prestressed cable-stayed bridge with CFRP cables and UHPC girder%CFRP拉索预应力超高性能混凝土斜拉桥力学性能分析

    Institute of Scientific and Technical Information of China (English)

    方志; 任亮; 凡凤红

    2012-01-01

    To discuss the applicability of carbon fiber reinforced polymer (CFRP) cables and reactive powder concrete ( RPC) in super-long span cable-stayed bridges, taking a 1 008 m cable-stayed bridge using steel girder and steel cables as example, a cable-stayed bridge with the same span using RPC (reactive powder concrete) as the girder and advanced composite material CFRP (carbon fiber reinforced polymer) as the cable was designed, in which the cable cross section was determined by the principles of equivalent cable strength and the beam cross section was determined considering the stiffness, shear capacity and local stability. Based on the method of finite element analysis, the comparative study of these two structures on their static properties, dynamic properties, stability and wind resistance were carried out. The results show that it is feasible for using RPC as the girder and CFRP as the cable so as to form a highly efficient, durable cable-stayed bridge of concrete structure and make its applicable span reach about 1 000 m long.%为了探讨碳纤维复合材料(carbon fiber reinforced polymer,CFRP)和超高性能活性粉末混凝土(reactive powder concrete,RPC)在超大跨度斜拉桥中应用的可行性,以主跨1008m的大跨度钢主梁斜拉桥设计方案为例,采用拉索的等强度原则将原桥钢索替换成CFRP索,考虑截面刚度、截面应力和局部稳定等要求,将原桥钢主梁替换成RPC主梁,拟订了一座等跨度的CFRP拉索、RPC主梁斜拉桥方案.采用有限元法分别对两种方案结构的静力特性、动力特性、稳定性能以及抗风性能等进行了分析与比较.结果表明:从结构受力性能角度而言,采用超高性能混凝土主梁和CFRP拉索构成千米级跨度混凝土斜拉桥的结构体系是可行的.

  1. Study on Flexural Behaviour of RC Beams Strengthened by CFRP Sheets%CFRP布加固钢筋混凝土梁的抗弯性能研究

    Institute of Scientific and Technical Information of China (English)

    张智梅; 考书姣; 白世烨

    2012-01-01

    首先,通过对一组外贴CFRP布加固的钢筋混凝土简支梁的抗弯承载力进行了理论公式计算,并总结出了各国加固规范给出的承载力计算公式的适用情况.其次,对同一组梁进行了有限元数值模拟,模拟了加固梁在四点弯曲荷载作用下的破坏过程,与试验数据进行了比较分析,验证了模型的合理性和有效性.最后,利用验证后的有限元模型进一步分析研究了相关参数对加固梁抗弯承载力的影响,提出了与配筋率相关的承载力修正系数,为加固工程实践提供了理论依据.%The theoretical formula to calculate the bending bearing capacity of simply supported RC beams strengthened with CFRP sheets was calculated firstly;and the applicable condition of strengthening codes in different countries was summarizd. Second;the finite element analysis was performed on the above RC beams. The failure process of four-point bending on the strengthened RC beams was simulated;and the comparative a-nalysis was done between the experimental results and the simulatied results. The correctness and effectiveness was verified. Finally;based on the finite element model which has been verified;further parameter studies on the bending bearing capacity of strengthened beams were carried out. The correction factor of bearing capacity related to reinforcement ratio was proposed. The model will provide theory basis for similar engineering strengthening.

  2. Finite Element Analysis and Study on Hysteretic Behaviors of Reinforced Concrete Beams Strengthened with CFRP and Steel%CFRP与钢板加固RC梁滞回性能有限元分析研究

    Institute of Scientific and Technical Information of China (English)

    刘勇; 杨霞

    2011-01-01

    Based on ANSYS finite element analysis software and by simulating the cyclic loading tests,the seismic performances of the RC beams strengthened with a CFRP and a steel are explored and studied respectively.The study results show that: through establishing a reasonable finite element analysis model and taking reasonable solution strategies,a better hysteresis curve graph could be drawn,thus to confirm a conclusion: the seismic performance of the RC beam strengthened with the steel is more excellent than that with the CFRP.%采用ANSYS有限元分析软件,通过模拟低周反复荷载试验,分别对1根CFRP加固RC梁和1根钢板加固RC梁的抗震性能进行了探究。研究表明:建立合理的有限元分析模型,采取合理的求解策略,可以得出较好的滞回曲线图形,从而证实了钢板加固RC梁比CFRP加固的RC梁的抗震性能优良的结论。

  3. 内嵌CFRP板加固已损伤RC梁抗弯性能的试验研究%Experimental study on the flexural behavior of damaged reinforced concrete beams strengthened with near-surface mounted CFRP laminates

    Institute of Scientific and Technical Information of China (English)

    孙志洋; 张智梅; 刘涛

    2013-01-01

    通过对7根钢筋混凝土梁内嵌CFRP板加固的抗弯试验,探讨了CFRP板用量、损伤程度和加固方式对已损伤钢筋混凝土梁承载力、跨中挠度、破坏形态等方面的影响.试验结果表明,与未加固梁相比,已损伤的钢筋混凝土梁采用内嵌CFRP板法加固后,混凝土梁的极限承载力提高了34%~144%;CFRP板的用量对钢筋混凝土梁的抗弯性能影响较大,损伤程度对加固梁抗弯性能的影响不明显,内嵌CFRP板加固钢筋混凝土梁的抗弯性能优于外贴等量CFRP板的加固梁.基于混凝土结构加固理论,考虑开槽数量的影响,对内嵌CFRP板加固已损伤RC梁钢筋屈服前的短期刚度进行理论分析,并建立加固梁钢筋屈服前短期刚度的计算公式,其计算结果与试验实测值吻合较好.%Seven reinforced concrete beams strengthened with NSM CFRP were tested.The ultimate moment,deflection at mid span,failure mode of the test beams with the strengthening amount,damage degree and the way of strengthened were discussed.The experimental results showed that the load-bearing capacity of the beams strengthened with NSM CFRP increases from 34% to 144% comparing with the beams which are not strengthened.The flexural behavior of the concrete beams were influenced by the strengthening amount,but the damage degree just has a little influence to the flexural behavior of the concrete beams.Near-surface mounted CFRP strengthening beams has more flexural than bonded CFRP sheets strengthening beams.In consideration of the influence of the groove,the short-term rigidity were discussed for NSM CFRP laminates-strengthened damaged RC beams on the basis of the theory of concrete structure,and introduces a practical calculating method of short-term rigidity.The predicted results agree well with the measured values from the tests of the present.

  4. Measurement of the prestress transfer length and load bending tests on an actual pretension type nan-magnetic beam provided with CFRP strand as tendon; CFRP yorisen wo kinchozai ni shiyoshita puretenshon hoshiki jitsubutsu hi jiseiryo no puresutoresu dentatsu cho sokutei shiken oyobi mage saika shiken

    Energy Technology Data Exchange (ETDEWEB)

    Kawamoto, Y. [P-S Corp., Tokyo (Japan); Nakata, A.; Akashi, K.

    1996-01-30

    When a new material of fiber reinforced plastics-strand of carbon fiber reinforced plastics(CFRP)-is used as an alternative to a PC steel material and low magnetic aggregates are selected for a demagnetized structure, it is considered that the physical and mechanical behaviors of such a PC member differ from that of the ordinary PC member. Therefore, in this report, characteristics of the new member are clarified and a design method for an actual low magnetic PC structure is discussed. Firstly, the main beam is outlined and an analysis is made on the prestress transfer length on the basis of stress variations measured on tendons, and the fact that the provision of stirrups in the beam terminal parts can prevent from its fracturing and cracking that may otherwise occurred by introduction of prestresses is demonstrated. Then the main beam displacement and the states of stress and crack of the structure members are examined. It is indicated from the findings that the ordinary PC design method can be applied to a design for which no crack is permitted, but the tendon rupture should be regarded as the bending fracture of the beam itself for beam designing purposes. Some future items for study are also shown. 17 refs., 10 figs., 7 tabs.

  5. Experiments Study on Fire Resistance of CFRP Shear Strengthened Reinforced Concrete Beam%CFRP抗剪加固钢筋混凝土梁的耐火性能试验研究

    Institute of Scientific and Technical Information of China (English)

    范鹤

    2011-01-01

    Fire-resistance performance experiments with static loading-fire are investigated about four CFRP shear strengthened and one without CFRP strengthened reinforced concrete (RC) beams exposed to the ISO834 standard fire. Shear strengthened RC beams are wrapped with fire insulation material- thick painted fire retardant coatings. Relationships between measure points temperature,displacement and time are achieved. The effects of different load mode, shear-span ratio, strength ratio and fire insulation thickness on the mid-span deflection, failure mode and fire-resistance rating of the shear strengthened RC beams are investigated. The results suggest that: With the same redundant bend or shear capacity, strengthening ratio, fire resistance of bend failure than shear failure; not bending-failure fire-resistance rating, but shear-failure fire-resistance rating is increased by thickening fire insulation to shear strengthened RC beams; mid-span deflection of shear failure is approximate one half of bending failure when shear strengthened RC beams. The experiment results give a supplement to research of CFRP strengthened structural members in fire.%采用厚型防火涂料对4根碳纤维布抗剪加固钢筋混凝土梁和1根对比梁进行了IS0834标准升温条件下的恒载升温耐火性能试验,得到了试验梁的测点温度、位移随时间增加的分布关系.分析了不同加载方式、剪跨比、加固量和防火保护层厚度对高温下CFRP抗剪加固梁的跨中挠度、破坏形态及耐火极限的影响.试验结果表明:在相同的弯、剪富余量,相等加固量条件下,高温下剪切破坏的耐火极限小于弯曲破坏的耐火极限;抗剪加固防火涂料的厚度可以提高剪切破坏的耐火极限,但不改变弯曲破坏的耐火极限;抗剪加固梁剪切破坏的跨中挠度近似为弯曲破坏的一半.试验结论补充了高温下CFRP加固构件的研究成果.

  6. 全封闭碳纤维与高强钢丝复合拉索的弹性模量%Elastic modulus of fully-enclosed composite cable made of CFRP and high-strength steel strand

    Institute of Scientific and Technical Information of China (English)

    陈云钢; 郭正兴; 刘家彬; 常瀚

    2011-01-01

    Coordination mechanism of the fully-enclosed composite cable is investigated, and the requirements that the elastic modulus of the high-strength steel strand and CFRP (carbon fiber reinforced polymer) should be equal is proposed in this paper. Firstly, the relationship between the twist and the elastic modulus of the high-strength steel strand is studied. Then, the calculation formula of the elastic modulus of the high-strength steel strand with 37 strands is derived. Finally, the correctness of the formula is verified by finite element analysis. Test results show that the elastic modulus of CFRP can reach that of high-strength steel strand. It is concluded that the force of the composite cable is distributed in accordance with the axial stiffness of carbon fiber and high-strength steel strand, and the elastic modulus of both CFRP and high-strength steel strand in fully-enclosed composite cable are equal. With the pull of the whole anchorage, the deformation of CFRP in fully-enclosed composite cable is consistent with the deformation of the high-strength steel strand. Equivalence of the elastic modulus determines that the force is distributed in accordance with the ratio of the cross-section of the carbon fiber and the high-strength steel strand, which can ensure the coordination mechanism of the fully-enclosed composite cable. The elastic modulus of the high-strength steel strand is associated with the twist and the torsion angle. With the decrease of the twist and increase of torsion angle, the elastic modulus of the high-strength steel strand decreases.%探讨了全封闭复合拉索的协调工作机理,即要求芯部高强钢丝束与碳纤维筋弹性模量接近或相等;研究了高强钢丝束捻距与弹性模量间的关系;推导了37股高强钢丝束弹性模量的计算表达式,通过有限元分析验证了表达式的正确性.试验表明,碳纤维筋弹性模量可以达到与高强钢丝束的弹性模量相近的要求.结论表明:复

  7. Experimental studies on shear behavior of concrete beams prestressed with CFRP tendons%预应力CFRP筋混凝土梁受剪性能试验研究

    Institute of Scientific and Technical Information of China (English)

    杜修力; 王作虎; 詹界东

    2011-01-01

    FRP筋是一种新型预应力筋材,具有轻质、高强、耐腐蚀、抗疲劳等优点,但是其横向剪切强度相对较低,这会影响预应力FRP筋混凝土梁的受剪承载力.通过27根混凝土梁的受剪试验,研究了预应力CFRP筋混凝土梁的剪切破坏形态,以及各种参数对其受剪承载力的影响,并与钢绞线预应力混凝土梁的受剪试验结果进行了比较.研究结果表明:预应力CFRP筋混凝上梁的剪切破坏形态有两种:斜压破坏和剪压破坏;剪跨比和配箍率是影响预应力CFRP筋混凝土梁受剪承载力的主要因素;有粘结预应力CFRP筋混凝土梁的受剪承载力比无粘结预应力CFRP筋混凝土梁要大15%左右;通过引入反映预应力筋种类和粘结条件的2个参数,提出了预应力FRP筋混凝土梁的简化受剪承载力计算式,计算结果与试验数据吻合较好.%As a new structural material, FRP (fiber reinforced plastics) features light weight, high strength, corrosion resistance, anti-fatigue, etc., and have a bright future when used as a new type of prestressing tendon in engineering structures.The horizontal shear strength of FRP tendon is low, which will affect the shear strength of concrete beams prestressed with FRP tendons.Based on experimental studies on 27 concrete beams prestressed with CFRP tendons, this paper studied the shear failure modes and a variety of parameters on shear strength, and compared the shear performance with concrete beams prestressed with steel strands.Studies show that there are two shear failure modes for concrete beams prestressed with FRP tendons, i.e.diagonal compression and shear-compression.Shear span ratio and stirrup rate are main factors influencing the shear behavior of concrete beams prestressed with CFRP tendons.The shear strength of concrete beams prestressed with bonded CFRP tendons is about 15% larger than that of concrete beams prestressed with unbonded CFRP tendons.A simple formula for computing

  8. Calculation of ductility of RC beams strengthened with CFRP and steel-plate%碳纤维布与钢板复合加固钢筋混凝土梁延性计算

    Institute of Scientific and Technical Information of China (English)

    熊学玉; 张序

    2011-01-01

    将碳纤维布与钢板结合起来对钢筋混凝土梁进行加固,试验表明,该方法虽能使构件的承载能力和刚度都得到显著地提高,但对延性的削弱也不可忽视.基于复合加固梁的受力特征,提出加固梁截面曲率延性系数的计算方法,并讨论了其影响因素.%Reinforced concrete beams were strengthened with CFRP and steel-plate, experiment result shows this method can significantly raise the capacity and stiffness, but also reduce the ductility. Base on the behavior of mixed-strengthened beams, a calculation method of curvature ductility coefficient is proposed, and some key factor is discussed.

  9. EXPERIMENTAL STUDY ON SHEAR PROPERTIES OF REINFORCED CONCRETE (RC) AND PARTIAL PRESTRESSED CONCRETE (PPC)BEAMS STRENGTHENED WITH EXTERNALLY BONDED CFRP STRIPS%CFRP板加固RC&PPC梁抗剪性能试验研究

    Institute of Scientific and Technical Information of China (English)

    宗周红; 程怡; 黄学漾; 林于东

    2013-01-01

    An experimental study and nonlinear finite element analysis including reinforced concrete (RC) beams and partial prestressed concrete (PPC) beams strengthened with CFRP strips were carried out under static loading.The influences of damage degree,ratio of shear span,stirrup ratio,and level of effective prestressing on the shear characteristics of these strengthened beams were investigated.Some important conclusions were extracted from the testing and numerical analysis and listed as follows:1) The inclined cracking development can be effectively restrained using the proposed strengthening method with CFRP strips,and the shear load-carrying capacity and ductility of the strengthened RC&PPC beams can be effectively improved.2) The synclinal cracking load,yielding loads of the stirrup,and the shear load-carrying capacity of RC beams strengthened after the damage would be enhanced while the ratios of shear span becoming smaller and stirrup ratio becoming larger.3)The improvements of shear carrying-capacity of PPC beams strengthened with CFRP strips would become larger if the level of effective prestressing increasing.4) The proposed nonlinear fimite element (FE) model can better predict the shear performance of strengthened RC&PPC beams,and the results from FE model can correlate very well with those from testing.5) The strength of CFRP strips should be effectively reduced during the shear strengthening design of the practical engineering cases.%通过10片普通钢筋混凝土(RC)梁及4片部分预应力混凝土(PPC)梁采用CFRP板抗剪加固的试验研究和非线性有限元分析,研究不同损伤程度、剪跨比、配箍率及预应力水平等因素对CFRP板加固RC&PPC梁抗剪性能的影响.结果表明:采用CFRP板对RC&PPC梁进行抗剪加固能够有效抑制斜裂缝的开展,提高加固梁斜截面抗剪承载能力,并改善梁的延性;RC梁损伤后加固,随着配箍率的增大以及剪跨比的减小,将提高加固RC梁的斜向开裂

  10. 遥感相机复合材料底板的成型工艺研究%Study on process of the CFRP motherboard in remote sensing camera

    Institute of Scientific and Technical Information of China (English)

    房海军

    2012-01-01

    This paper introduced the constituent of the CFRP motherboard in remote sensing camera. To improve the stiffness and strength of the motherboard, analysis on materials structure and so on were carried out. By choosing appropriate materials molding one integrative CFRP strengthened frame in the motherboard and adapting sandwich structure was able to make the motherboard meet the requirements for the lightweight and other performances. In addition, the forming technology and difficulty of this process were analyzed. The results show that the technical indicators of the successfully developed motherboard subjected to the ground tests and the onorbit tests met the design requirements and achieved the expected results.%简述了某型号遥感相机复合材料底板的组成。为提高相机底板的强度和刚度,经分析研究,通过合理选材和优化结构,在相机底板中设置了碳纤维复合材料整体加强框架,且采用轻质高强的蜂窝夹层结构,确保该制件轻量化的要求;同时,还对该制件成型工艺过程和技术难点进行分析。结果表明,研制成功的该制件经受地面试验和在轨运行试验,各项技术指标均满足设计要求,取得预期的成效。

  11. CFRP板加固受弯钢梁的承载力及挠度分析%Bearing Capacity and Deflection Analysis of Bending Steel Beams Strengthened with CFRP Plates

    Institute of Scientific and Technical Information of China (English)

    张鹏; 叶黎明; 邓朗妮; 钟鑫

    2011-01-01

    采用截面等效代换法,对碳纤维板加固受弯钢梁进行了承载力及挠度分析,推导出CFRP板加固受弯钢梁的理论计算公式.为验证公式,进行了5根CFRP板加固钢梁的单调静力试验,并用有限元软件进行模拟分析,将计算结果分别与试验结果和有限元分析结果进行比较后发现:弯矩理论计算值比试验值略小,挠度理论计算值比试验值略大,且都与有限元模拟值相近,说明理论计算安全,计算方法具有良好的适用性.%The method of using one section to exchange another is used to study bearing capacity and deflection analysis of bending steel beams strengthened with carbon fiber-reinforced polymer (CFRP) plates. The theoretical formula of bending steel reinforced beams is worked out. Five reinforced beams are used in the monotonic static experiment for validating the formula. Finite element software is applied to simulate and analyze the strengthened beams. The calculation result is compared with the experiment and finite element simulation results and analyzed. The calculated value is less than experimental value of bending moment while the calculated value is bigger than experimental value of deflection. Both calculated values are approaching to the simulation results. It shows that the calculating is safe and the calculating method has good applicability. The formula can be used as reference in the project of designing steel beams reinforced by CFRP plates.

  12. Laminated and pasting CFRP composite strengthening RC beam bending bearing capacity experimental study%叠合与粘贴CFRP复合加固RC简支梁的抗弯承载力试验研究

    Institute of Scientific and Technical Information of China (English)

    李红霞; 郭艳芹; 张雷顺

    2013-01-01

    通过分析叠合与粘贴CFRP复合加固RC简支梁承载力的两大主要影响因素,运用现有计算方法推导得出复合加固RC梁的抗弯承载力计算公式,试验发现:仅粘贴CFRP加固RC梁,虽能有效提高构件承载力,但由于下部受拉储备充足而使上部受压储备相对不足,使构件发生类似超筋梁的脆性破坏,其极限承载力明显低于上部同时有叠合层的RC梁.试验比较发现:所用计算方法得出的计算值与试验值相比偏小,计算公式偏于保守.%Through the analysis of laminated composite of RC beams strengthened with bonded CFRP bearing force of the two major influencing factors, using the existing calculation method of composite strengthening RC beam is derived the formula to calculate the bending bearing capacity, test found that: only paste CFRP strengthened RC beams, can effectively improve the bearing capacity of members, but due to the lower tensile reserves and the upper compression reserve is relatively insufficient, make a component similar over-reinforced beam brittle failure, its ultimate bearing capacity was significantly lower than the upper part while the laminated layer of RC beam. Test comparison showed that:this method calculated value compared with experiment data is small,conservative calculation formula.

  13. Ultrasonic characterization of CFRP anisotropy

    Czech Academy of Sciences Publication Activity Database

    Kling, M.; Tokar, Daniel; Převorovský, Zdeněk

    Praha: ČVUT v Praze, 2015 - (Hobza, T.), s. 71-80 ISBN 978-80-01-05841-1. [Stochastic and Physical Monitoring Systems 2015. Praha (CZ), 22.06.2015-27.06.2015] Institutional support: RVO:61388998 Keywords : anisotropy * carbon fiber -reinforced plastic * ultrasonic testing * signal processing Subject RIV: BI - Acoustics

  14. FINITE ELEMENT ANALYSIS OF SEISMIC BEHAVIOR OF RC FRAME JOINTS INDIRECTLY STRENGTHENED WITH TIED AND LOCK-ANCHORED CFRP SHEETS%系锚碳纤维布间接加固混凝土框架节点抗震性能有限元分析

    Institute of Scientific and Technical Information of China (English)

    贺学军; 余晓光; 周朝阳; 刘澍; 吴绪康

    2015-01-01

    系锚碳纤维布(简称CFRP)间接加固混凝土框架节点方法能够有效避免直接粘贴加固CFRP易剥离、难以在实际工程中实施等缺陷。通过对5个系锚CFRP间接加固节点在滞回曲线、节点承载力和延性系数等方面的有限元数值模拟对比分析,探讨节点梁端箍筋配箍率、纵向CFRP条带用量及横向CFRP条箍用量等参数对节点抗震性能的影响。分析结果表明:梁柱端间接加固的系锚CFRP能明显改善节点的抗震性能,其极限承载能力和梁端位移延性系数提高幅度分别达到19.8%和55.5%;在其他参数相同的情况下,增加梁端纵向CFRP条带的配置率能同时提高加固节点的抗震延性和承载能力,梁端箍筋配箍率能显著改善其抗震延性,梁柱端横向CFRP条箍配置率对加固节点的抗震延性和承载能力的提高作用不大,但能有效延缓纵筋的屈服和黏结滑移。%The method of indirectly strengthening RC frame joints with tied and lock-anchored carbon fiber reinforced polymer ( CFRP ) sheets can effectively avoid debonding of CFRP and infeasibility in practice which exist in strengthening directly.Based on the numerical simulation comparative analysis of the five strengthened joints'hysteresis curves, bearing capacity and ductility coefficient, the influence of the parameters on the seismic performance of the joints strengthened with tied and lock-anchored CFRP sheets was discussed.The influencing parameters included the ratio of stirrup , longitudinal CFRP sheets at the beam end and the amount of lateral shear CFRP at the beam and column end.The results showed that the tied and lock-anchored CFRP sheets could significantly improve the seismic performance of the joints.The maximum increase in ultimate bearing capacity and ductility coefficient of beam end was up to19.8% and 55.5% respectively.When others remained invariable, increasing the ratio of longitudinal CFRP sheets at the

  15. Avaliação do desempenho de uma técnica para aplicação de pós-tensão em mantas de CFRP no confinamento de pilares de betão armado

    OpenAIRE

    Agante, Marta A. B.; Júlio, Eduardo; Barros, Joaquim A.O.; Santos, João M. C.

    2008-01-01

    Diversos estudos comprovam que o reforço ao confinamento de pilares de betão armado com mantas de CFRP é uma técnica extremamente eficaz no caso de pilares de secção transversal circular, mas muito pouco eficaz no caso de pilares de secção rectangular. Algumas tentativas para ultrapassar esta situação incluíram o pré-esforço do encamisamento de CFRP através da injecção sob pressão de resinas de epóxido. Contudo, os resultados foram marginalmente satisfatórios e esta técnica revelo...

  16. 碳纤维布约束下钢纤维混凝土与腐蚀钢筋黏结性能的试验研究%Bond behavior of corroded reinforcement in steel fibrous concrete strengthened with CFRP

    Institute of Scientific and Technical Information of China (English)

    邓宗才; 万操

    2012-01-01

    A total of 96 test specimens with embedded reinforcing bars were strengthened by two layer of transverse CFRP (carbon fiber sheets) after accelerated corrosion. Pullout tests on the specimens were conducted to study the effect of CFRP confinement on the bond behavior between corroded reinforcement and steel fibrous concrete, considering the contributions of different elements, including reinforcing bar types, cover depths, corrosion rates, CFRP confinements, and steel fiber. The failure mechanisms were studied. The test results show that CFRP confinements can make the failure mode of deformed reinforcing bar specimens change from steel fibrous concrete splitting to bar pull-out. The main influencing factors of the ultimate bond strength are reinforcement bar types and cover depths, the ultimate bond strength of deformed reinforcement bar specimens is twice as large as that of plain reinforcement bar specimens, and the ultimate bond strength increases when the cover depth changes from 40mm to 60mm. CFRP is effective on slowing down the bond stress reduction rate and maintaining the bond strength. When the corrosion rate is less than 5% , the ultimate bond strength of corroded steel fibrous concrete specimens increases gradually along with the rise of corrosion rate, and decreases when the corrosion rate is higher than 5 %. The steel fiber can increase the bond strength of reinforcement and steel fibrous concrete effectively, and make the descending branch of bond-slip curves much smoother.%为研究碳纤维布加固对腐蚀钢筋与钢纤维混凝土黏结性能的效用,采用外加电流法对96个预埋钢筋-钢纤维混凝土试件进行加速腐蚀,腐蚀完成后横向包裹两层单向碳纤维布;通过拉拔试验研究纤维布约束对腐蚀钢筋与钢纤维混凝土黏结性能的影响规律,并与普通混凝土试验结果进行对比分析,探讨钢筋种类、保护层厚度、腐蚀率、纤维布约束及钢纤维等对

  17. EXPERIMENTAL STUDY ON FLEXURAL BEHAVIOR OF RC BEAMS STRENGTHENED WITH CFRP SHEETS%碳纤维板加固钢筋混凝土梁抗弯性能试验

    Institute of Scientific and Technical Information of China (English)

    李琪

    2012-01-01

    In this paper, the experiment selected carbon fiber-reinforced plates sheets' different width, amounts, anchoring or not and different anchoring methods as parameters. 9 RC beams strengthened with carbon fiber-reinforced plate sheets were tested to investigate the flexural behavior. The experimental results showed that the flexural load-carrying capacity and stiffness were increased effectively and the propagation of cracks was reduced obviously by the rehabilitation. Flexural load-carrying capacity of RC beams with CFRP sheets end anchorage has been strengthened remarkably.%选择不同的碳纤维板板宽、数量、有无锚固措施及不同的锚固方式等作为试验参数,对9根采用碳纤维板加固的钢筋混凝土梁进行了抗弯性能研究.试验结果表明:这些加固措施有效地提高了梁的抗弯极限承载力和刚度,较好地约束裂缝的发展,具有良好的加固效果.有良好锚固措施时,其抗弯承载力显著提高.

  18. ADVANCE IN HIGH-STRENGTH CONCRETE FILLED SQUARE STEEL TUBULAR STRUCTURE WITH INNER CFRP CIRCULAR TUBE%内置CFRP圆管的方钢管高强混凝土结构研究进展

    Institute of Scientific and Technical Information of China (English)

    李帼昌; 张春雨; 于洪平

    2012-01-01

    该文进行了内置CFRP圆管的方钢管高强混凝土结构的轴压短柱、轴压中长柱、轴压长柱、纯弯构件、单向偏压短柱、单向偏压中长柱、双向偏压短柱、双向偏压中长柱的试验研究和有限元模拟,分析了内置CFRP圆管的方钢管高强混凝土结构各类基本构件的受力全过程以及破坏模式,并提出了用于计算该结构各类基本构件的承载力以及变形的计算公式.在试验研究和数值模拟的基础上,将此种新型组合结构构件的力学性能与方钢管混凝土构件的力学性能进行了比较分析.%Plentiful experiment researches and the finite element analysis are performed on short and slender columns under axial compression beams, short columns and slender columns under eccentric compression, short columns and slender columns of high-strength concrete filled square steel tube with inner CFRP circular tube under bi-axial eccentric compression. The failure mode and the mechanism of all kinds of members in an entire process are analyzed. And a simplified formula calculating the bearing capacity for each member is proposed. On the basis of above, the comparison between this new composite structure and a traditional concrete filled square steel tubular structure is done.

  19. Flexural Behaviors of Ultra High Performance Concrete T Beams Prestressed with CFRP Tendons%CFRP预应力筋超高性能混凝土T梁的受弯性能

    Institute of Scientific and Technical Information of China (English)

    杨剑; 方志

    2009-01-01

    超高性能混凝土(UHPC)和碳纤维(CFRP)以其优异的性能成为土木工程领域极具应用前景的新型建筑材料,将两者结合在一起有望形成一种新的具有优良物理力学性能的配筋混凝土结构型式而应用于实际工程.为此,对超高性能混凝土的单轴受压应力-应变全曲线和UHPC梁的受力性能进行试验研究以及理论分析.试验参数主要选取预应力度、张拉控制应力和CFRP筋的黏结方式.试验结果表明,UHPC具有良好的受压变形性能,基于单轴受压试验结果建立UHPC的受压应力-应变全曲线方程;UHPC梁具有良好的变形能力以及合理的裂缝分布,其极限变形可达到梁跨径的1/30~1/72,在此基础上提出的计算方法能对所研究梁的受力性能进行较好的模拟.

  20. 初始荷载对RC梁碳纤维布抗弯加固效果影响的有限元分析%Finite-element Analysis of Effect of Initial Load on Bending Capacity of Reinforced Concrete Beam Strengthened with CFRP

    Institute of Scientific and Technical Information of China (English)

    武志杰; 陈悦

    2013-01-01

    利用ANSYS建立14根碳纤维布加固钢筋混凝土简支梁模型,分析在两种配筋率情况下,不同初始荷载对钢筋混凝土梁碳纤维布抗弯加固效果的影响。结果表明:碳纤维布加固可显著提高梁的屈服荷载和极限荷载,梁的屈服荷载和极限荷载的提高幅度随着初始荷载的增加而减小;配筋率越小,受拉钢筋利用越充分,梁的极限荷载提高幅度越明显。%Fourteen reinforced concrete simply supported beam models with CFRP sheets were built by using ANSYS, and the influence of different initial loads on the reinforcement and flexural strength effects of CFRP sheets in two steel rein-forcement ratios was analyzed. The results indicated that reinforced carbon fiber sheet could significantly increase the yield-ing load and ultimate load of the beam. The enhancement of yielding load and ultimate load decreased with the increase of initial load. The more adequate the steel reinforcement utilization rate was, the more significantly the ultimate load with small reinforcement ratio would be improved.

  1. 碳纤维增强复合材料修复震后玻璃纤维增强复合材料管钢筋混凝土桥墩柱抗震性能试验%EXPERIMENTAL INVESTIGATION ON THE SEISMIC BEHAVIOR OF SEVERE EARTHQUAKE-DAMAGED GFRP TUBED REINFORCED CONCRETE BRIDGE PIERS REPAIRED WITH WRAPPED CFRP SHEETS

    Institute of Scientific and Technical Information of China (English)

    王清湘; 王轩

    2011-01-01

    In order to investigate the seismic behavior of earthquake-damaged GFRP (Glass Fiber Reinforced Polymer) tubed reinforced concrete bridge piers repaired with wrapped CFRP (carbon fiber reinforced polymer or plastics) sheets, four GFRP tubed RC bridge piers repaired with wrapped CFRP sheets were tested under repeat low cyclic load. The hysteresis loops, skeleton curves, ductility and energy dissipation ability of the repaired RC bridge piers were compared with those of the original piers. Research show that the bearing capacity and ductility of the repaired bridge piers can be restored or even improved.%为了研究碳纤维增强复合材料(CFRP)修复震后玻璃纤维增强复合材料(GFRP)管混凝土桥墩柱的抗震性能,对4根CFRP修复震后破坏GFRP管混凝土桥墩柱进行拟静力试验,对比修复后钢筋混凝土桥墩柱与原型桥墩柱的滞回曲线、骨架曲线、延性和耗能能力。试验结果表明,修复后的墩柱承载力和延性指标均能得到较好的恢复甚至提高。

  2. Experimental Research on the Cracking Behavior of Reinforced Concrete Beams Combination Strengthened with Bonded CFRP and Steel Plate%碳纤维与钢板复合加固钢筋混凝土梁裂缝的试验研究

    Institute of Scientific and Technical Information of China (English)

    熊学玉; 徐海峰

    2012-01-01

    Through the flexural test of one reference beam, three combination strengthened beams and three CFRP reinforced beams, the cracking mechanism and the calculation of crack width of reinforced concrete beams combination strengthened with bonded CFRP and steel plate were studied. Study shows that the crack distance and crack width of strengthened beams are less than those of reference beams, but the secondary crack has increased. The crack growth rate of combination strengthened beams is slower than that of CFRP reinforced beams, which illustrates that combination reinforcement is better than CFRP reinforcement in the role of limiting crack. With the increase of service loading, the crack development speed of reinforcement beams accelerates, and the effect of limiting crack will reduce with it. The maximum crack width curve also appears mutations, which explains that service loading has reduced the effect on limiting crack. However, the service loading has less role of limiting crack on combination reinforcement than CFRP reinforcement. On the basis of traditional crack calculation theory, the adhesive correlation coefficients of combination strengthening and the influence coefficient of service loading are introduced to derive the formula for calculating the crack width of combination strengthened beam considering service loading and adhesive correlation coefficients. The calculation result of crack width is in good agreement with test result. The calculation method is simple and convenient and can be applied to engineering design.%通过1根原梁、3根碳纤维与钢板复合加固梁和3根碳纤维加固梁的受弯性能试验,研究碳纤维与钢板复合加固钢筋混凝土梁的裂缝发展机理及裂缝宽度计算方法.研究表明,加固梁的裂缝间距和裂缝宽度均小于原梁,但次生裂缝有所增加;复合加固梁的裂缝发展速度比碳纤维加固梁缓慢,说明复合加固的限裂作用优于碳纤维;随着负载的增加,

  3. Experimental study and analytical moaeiing of prestress losses of reinforced concrete beams strengthened with post-tensioned CFRP sheets%后张预应力碳纤维布加固钢筋混凝土梁预应力损失试验及计算方法研究

    Institute of Scientific and Technical Information of China (English)

    王文炜; 戴建国; 张磊

    2012-01-01

    该文进行4根预应力碳纤维布加固钢筋混凝土梁预臆力损失试验研究。在试验研究的基础上,基于国内外相关的混凝土结构规范给出预应力损失计算方法。为验证计算方法的有效性,对该文和其他学者的试验结果进行比较分析。试验结果表明,放张过程中预膻力碳纤维布与锚具间滑移及锚具变形造成的瞬时损失是主要部分,占初始预应力的12.6%~18.2%,而时间依存的损失仅为初始坝应力的2.3%~3.9%。胶体的养护时问对瞬时损失具有一定的影响。计算结果表明,该文建立的计算方法与试验值吻合较好,可以较有效地预测预应力损失。%Experimental tests were conducted for four reinforced concrete beams strengthened with post-tensioned carbon fiber reinibreed polymer (CFRP) sheets to investigate the short and long-term prestress losses. An analytical model, based on existing design specifications for prestressing reinibreed concrete structures, is presented to predict such prestress losses. The experimental results showed that the instantaneous prestress loss due to anchorage set was the main part of the total prestress loss and was about 12.6% - 18.2% of the initial prestress in CFRP. The time-dependent prestress loss was only 2.3% - 3.9% of the initial prestress in CFRP. The curing period of epoxy resin until the release of prestress affects significantly the instantaneous prestress loss. The analytical modei is validated through comparisons with the authors' and other researchers' test results.

  4. EXPERIMENTAL STUDY OF SEISMIC BEHAVIORS OF CORRODED REINFORCED CONCRETE COLUMNS STRENGTHENED WITH WRAPPED CFRP SHEETS%碳纤维增强材料加固锈蚀钢筋混凝土柱的抗震性能试验研究

    Institute of Scientific and Technical Information of China (English)

    蒋凤昌; 姜晔; 陈红秋; 奚友方; 居平国

    2013-01-01

    钢筋锈蚀以致局部箍筋锈断将会降低混凝土柱的抗震性能,采取碳纤维增强材料( CFRP)加固方法可对此类锈蚀钢筋混凝土柱的抗震性能进行修补。基于28根T形柱的试验研究,初步揭示了钢筋锈蚀率、轴压比、CFRP加固方式和加固层数对混凝土柱抗震性能影响规律。钢筋锈蚀会导致混凝土柱的耗能能力、刚度、承载力和延性不同程度的降低。当钢筋锈蚀率达到15%时,混凝土柱的延性系数下降约40%。经过CFRP加固后,锈蚀柱的滞回环变得较为饱满,耗能能力大大增强,其延性系数可提高约40%,耗能能力可提高约80%。%Due to corrosion or disruption of stirrups in some parts of the coloumn , could seismic behaviors of corroded reinforced concrete columns would cut down , and could be recovered by strengthening with wrapped CFRP sheets . Based on experimental study of 28 T-shaped concrete columns , the laws were revealed that seismic behaviors of concrete columns were affected by rate of reinforcement corrosion , axial compression ratio , strengthening style and layers of wrapped CFRP sheets .Reinforcement corrosion could reduce columns ’ behaviors of energy dissipation , rigidity, capacity and ductility to some degree .The ductility coefficient could be decreased by 40%when the rate of reinforcement corrosion was up to 15%.Strengthened with wrapped CFRP sheets , corroded reinforced concrete columns raised largely their behaviors of energy dissipation , with more full hysteresis loop , and their ductility coefficient could be improved 40%, behaviors of energy dissipation could be raised by 80%.

  5. RETROFITTING OF CONCRETE CIRCULAR COLUMNS USING CFRP

    OpenAIRE

    Dr. R. Rajkumar*, Akkineni Surya Teja

    2016-01-01

    Structures of architectural importance present a number of challenges in restoration and retrofit, which limit the application of modern codes and building standards. Recommendations are desirable and necessary to ensure rational methods of analysis and repair methods appropriate to the cultural context. Retrofit specifically aims to enhance the structural capacities (strength, stiffness, ductility, stability and integrity) of a building that is found to be deficient or vulnerable. In the spe...

  6. Investigation on drilling-grinding of CFRP

    Institute of Scientific and Technical Information of China (English)

    Yanming QUAN; Wenwang ZHONG

    2009-01-01

    It is difficult to machine polymer matrix composites reinforced by carbon fibre, and the hole-making process is the most necessary machining process for composite plate products. Conventional drills have a very short life in the drilling of this kind of composites and the quality of the hole is very poor. In this paper, the cemented or plated diamond core tools are tested to make holes in carbon fibre/epoxy composite plates. The effects of machining parameters, cooling and chip removal on the tool life, and the hole quality are investigated. The results indicate that the material removal mechanism of the two kinds of diamond tools is not like the cutting effect of the conventional drilling but similar to that of grinding. Satisfactory effects in making holes in the composites are obtained--quite acceptable machined hole quality, low costs, and long wear-resistant endurance.

  7. CFRP lightweight structures for extremely large telescopes

    DEFF Research Database (Denmark)

    Jessen, Niels Christian; Nørgaard-Nielsen, Hans Ulrik; Schroll, J.

    2008-01-01

    Telescope structures are traditionally built out of steel. To improve the possibility of realizing the ambitious extremely large telescopes, materials with a higher specific stiffness and a lower coefficient of thermal expansion are needed. An important possibility is Carbon Fibre Reinforced Plas...

  8. Program specialization

    CERN Document Server

    Marlet, Renaud

    2013-01-01

    This book presents the principles and techniques of program specialization - a general method to make programs faster (and possibly smaller) when some inputs can be known in advance. As an illustration, it describes the architecture of Tempo, an offline program specializer for C that can also specialize code at runtime, and provides figures for concrete applications in various domains. Technical details address issues related to program analysis precision, value reification, incomplete program specialization, strategies to exploit specialized program, incremental specialization, and data speci

  9. Inexact Programming

    OpenAIRE

    Mahmood, Muhammad Yasir

    2012-01-01

    Two types of fuzzy linear programming i.e. fuzzy number linear programming and interval number linear programming are used for optimization problems. In interval form of linear programming we convert the inequalities from the feasible region, containing intervals as coefficients, to two groups of inequalities characterized by real, exact coefficients values. Then classical programming has been used to achieve an optimal solution in the feasible region. In fuzzy number linear programming, α‐cu...

  10. Programs To Aid FORTRAN Programming

    Science.gov (United States)

    Ragosta, Arthur E.

    1987-01-01

    Program-development time decreased while program quality increased. FORTRAN Programming Tools are series of programming tools used to support development and maintenance of FORTRAN 77 source codes. Included are debugging aid, central-processing-unit time-monitoring program, source-code maintenance aids, print utilities, and library of useful, well-documented programs. Tools assist in reducing development time and encouraging high-quality programming. Although intended primarily for FORTRAN programmers, some tools used on data files and other programming languages. Written in FORTRAN 77.

  11. 碳纤维增强复合材料筋复合型锚具试验研究和有限元分析%EXPERIMENTAL INVESTIGATION AND FINITE ELEMENT ANALYSIS OF WEDGE-BOND ANCHORAGE FOR CFRP-TENDONS

    Institute of Scientific and Technical Information of China (English)

    刘荣桂; 李明君; 刘德鑫; 蔡东升; 谢桂华

    2012-01-01

    In order to colligate the virtue of bonding-anchor and wedge-anchor, the wedge-bond anchorage for CFRP tendons was investigated, which was made by bonding and wedge parts, working in parallel. Based on the characteristics of exiting CFRP tendon anchors and according to a series of static load tests, it was studied the bonding property of colloid, and the influence of bond length, colloids thickness on the performance of straight pipe bonding anchorage. The static load test of wedge-bond anchorage was conducted to investigate its failure mode, ultimate load, slip deformation, etc. Transport mechanism of anchorage stress is preliminarily analysed according to variation of actual stress in the anchorage zone. The influences of variation in specific parameters, such as wedge slope, angular differential, presetting load, on the internal stress of the anchorage were simulated by using finite element method. And the suggested design parameters were offered. Which can provide academic reference for the optimization of wedge-bond anchorage.%为综合粘结型锚具与夹片型锚具各自的优点,在已有碳纤维增强复合材料(简称CFRP)筋锚具的基础上,研究由粘结部分与夹持部分协同工作而成的复合型锚具。由直筒粘结型锚具的静载试验,研究胶体粘结性能,粘结长度、胶体厚度对锚固性能的影响。通过复合型锚具静载试验,研究该类锚具的失效模式、极限荷载、滑移变形等,结合锚固区实测应力变化,初步分析锚固应力的传递机制。通过有限元分析方法,模拟计算夹片倾角、锥角差、预紧力等参数对复合型锚具内部受力的影响,得到建议设计参数,为复合型锚具结构优化提供参考。

  12. Quasiconvex Programming

    OpenAIRE

    Eppstein, David

    2004-01-01

    We define quasiconvex programming, a form of generalized linear programming in which one seeks the point minimizing the pointwise maximum of a collection of quasiconvex functions. We survey algorithms for solving quasiconvex programs either numerically or via generalizations of the dual simplex method from linear programming, and describe varied applications of this geometric optimization technique in meshing, scientific computation, information visualization, automated algorithm analysis, an...

  13. Effective Programming

    DEFF Research Database (Denmark)

    Frost, Jacob

    To investigate the use of VTLoE as a basis for formal derivation of functional programs with effects. As a part of the process, a number of issues central to effective formal programming are considered. In particular it is considered how to develop a proof system suitable for pratical reasoning......, how to implement this system in the generic proof assistant Isabelle and finally how to apply the logic and the implementation to programming....

  14. Program Fullerene

    DEFF Research Database (Denmark)

    Wirz, Lukas; Peter, Schwerdtfeger,; Avery, James Emil

    2013-01-01

    Fullerene (Version 4.4), is a general purpose open-source program that can generate any fullerene isomer, perform topological and graph theoretical analysis, as well as calculate a number of physical and chemical properties. The program creates symmetric planar drawings of the fullerene graph......-Fowler, and Brinkmann-Fowler vertex insertions. The program is written in standard Fortran and C++, and can easily be installed on a Linux or UNIX environment....

  15. Programming F#

    CERN Document Server

    Smith, Chris

    2009-01-01

    Why learn F#? This multi-paradigm language not only offers you an enormous productivity boost through functional programming, it also lets you develop applications using your existing object-oriented and imperative programming skills. With Programming F#, you'll quickly discover the many advantages of Microsoft's new language, which includes access to all the great tools and libraries of the .NET platform. Learn how to reap the benefits of functional programming for your next project -- whether it's quantitative computing, large-scale data exploration, or even a pursuit of your own. With th

  16. Programming Interactivity

    CERN Document Server

    Noble, Joshua

    2009-01-01

    Make cool stuff. If you're a designer or artist without a lot of programming experience, this book will teach you to work with 2D and 3D graphics, sound, physical interaction, and electronic circuitry to create all sorts of interesting and compelling experiences -- online and off. Programming Interactivity explains programming and electrical engineering basics, and introduces three freely available tools created specifically for artists and designers: Processing, a Java-based programming language and environment for building projects on the desktop, Web, or mobile phonesArduino, a system t

  17. The application of advanced remote systems technology to future waste handling facilities: Waste Systems Data and Development Program

    International Nuclear Information System (INIS)

    The Consolidated Fuel Reprocessing Program (CFRP) at the Oak Ridge National Laboratory (ORNL) has been advancing the technology in remote handling and remote maintenance of in-cell systems planned for future US nuclear fuel reprocessing plants. Much of the experience and technology developed over the past decade in this endeavor are directly applicable to the in-cell systems being considered for the facilities of the Federal Waste Management System (FWMS). The ORNL developments are based on the application of teleoperated force-reflecting servomanipulators controlled by an operator completely removed from the hazardous environment. These developments address the nonrepetitive nature of remote maintenance in the unstructured environments encountered in a waste handling facility. Employing technological advancements in dexterous manipulators, as well as basic design guidelines that have been developed for remotely maintained equipment and processes, can increase operation and maintenance system capabilities, thereby allowing the attainment of two FWMS major objectives: decreasing plant personnel radiation exposure and increasing plant availability by decreasing the mean-time-to-repair in-cell maintenance and process equipment. 5 refs., 7 figs

  18. Cicop program

    International Nuclear Information System (INIS)

    It is described the input data for using in the Cicop computer code in the Honeywell Bull computer of CNEN. It is a program to prepare microscopic cross section library in a proper format to be directly used by the Citation program from the Macroscopic cross section and isotope concentration. (Author)

  19. BASIC Programming.

    Science.gov (United States)

    Jennings, Carol Ann

    Designed for use by both secondary- and postsecondary-level business teachers, this curriculum guide consists of 10 units of instructional materials dealing with Beginners All-Purpose Symbol Instruction Code (BASIC) programing. Topics of the individual lessons are numbering BASIC programs and using the PRINT, END, and REM statements; system…

  20. Choreographic Programming

    DEFF Research Database (Denmark)

    Montesi, Fabrizio

    , as they offer a concise view of the message flows enacted by a system. For this reason, in the last decade choreographies have been used in the development of programming languages, giving rise to a programming paradigm that in this dissertation we refer to as Choreographic Programming. Recent studies show...... endpoint described in a choreography can then be automatically generated, ensuring that such implementations are safe by construction. However, current formal models for choreographies do not deal with critical aspects of distributed programming, such as asynchrony, mobility, modularity, and multiparty...... sessions; it remains thus unclear whether choreographies can still guarantee safety when dealing with such nontrivial features. This PhD dissertation argues for the suitability of choreographic programming as a paradigm for the development of safe distributed systems. We proceed by investigating its...

  1. Programming Python

    CERN Document Server

    Lutz, Mark

    2011-01-01

    If you've mastered Python's fundamentals, you're ready to start using it to get real work done. Programming Python will show you how, with in-depth tutorials on the language's primary application domains: system administration, GUIs, and the Web. You'll also explore how Python is used in databases, networking, front-end scripting layers, text processing, and more. This book focuses on commonly used tools and libraries to give you a comprehensive understanding of Python's many roles in practical, real-world programming. You'll learn language syntax and programming techniques in a clear and co

  2. NORD program

    International Nuclear Information System (INIS)

    A procedure of estimating the state of the WWER-1000 core power density on the basic of the in-core instrumentation system data is presented. A NORD program realizing this procedure in BASIC has been developed for on-line processing of experimental data. The program is designed for operation in dialog mode, has a service input-output unit and a unit for statistical processing of experimental results. The program makes it possible to evaluate quantitatively the differences of the power density fields obtained on the basis of readings taken from temperature control detectors and detectors of the neutron measuring channels. 5 refs.; 3 tabs

  3. Program overview

    International Nuclear Information System (INIS)

    The program overview describes the following resources and facilities; laser facilities, main laser room, target room, energy storage, laboratory area, building support systems, general plant project, and the new trailer complex

  4. [Mentoring program].

    Science.gov (United States)

    Watanabe, N

    2001-11-01

    Due to drastic changes in the business environment and prolonged recession, stress management practices in business organizations have been encountering two kinds of problems: budget cuts and difficulties in the delivery of services. The feasibility of mentoring programs to cope with these two problems is discussed. Through an extensive review of the literature, it becomes clear that mentoring programs have the following features and advantages; (1) One to one relationship between elder mentor and younger protégé has a favorable effect on the both mentor and protégé's mental health. (2) Formal mentoring programs are widely used in the U.S. for the prevention of juvenile delinquency, professional education, and human resource development in business settings. (3) Mentoring programs, in general, are practiced with the cooperation of kindred volunteers and professionals who monitor the mentor-protégé relationships. (4) Since a mentoring program utilizes a wide range of human resources in work organizations, it is able to overcome the "budget and delivery" problems. Further discussions are about the comparison with listener programs as well as the relationship with the total human resource management system. PMID:11802451

  5. Integer programming

    CERN Document Server

    Conforti, Michele; Zambelli, Giacomo

    2014-01-01

    This book is an elegant and rigorous presentation of integer programming, exposing the subject’s mathematical depth and broad applicability. Special attention is given to the theory behind the algorithms used in state-of-the-art solvers. An abundance of concrete examples and exercises of both theoretical and real-world interest explore the wide range of applications and ramifications of the theory. Each chapter is accompanied by an expertly informed guide to the literature and special topics, rounding out the reader’s understanding and serving as a gateway to deeper study. Key topics include: formulations polyhedral theory cutting planes decomposition enumeration semidefinite relaxations Written by renowned experts in integer programming and combinatorial optimization, Integer Programming is destined to become an essential text in the field.

  6. Programming Algol

    CERN Document Server

    Malcolme-Lawes, D J

    2014-01-01

    Programming - ALGOL describes the basics of computer programming using Algol. Commands that could be added to Algol and could increase its scope are described, including multiplication and division and the use of brackets. The idea of labeling or naming a command is also explained, along with a command allowing two alternative results. Most of the important features of Algol syntax are discussed, and examples of compound statements (that is, sets of commands enclosed by a begin ... end command) are given.Comprised of 11 chapters, this book begins with an introduction to the digital computer an

  7. Programming Interactivity

    CERN Document Server

    Noble, Joshua

    2012-01-01

    Ready to create rich interactive experiences with your artwork, designs, or prototypes? This is the ideal place to start. With this hands-on guide, you'll explore several themes in interactive art and design-including 3D graphics, sound, physical interaction, computer vision, and geolocation-and learn the basic programming and electronics concepts you need to implement them. No previous experience is necessary. You'll get a complete introduction to three free tools created specifically for artists and designers: the Processing programming language, the Arduino microcontroller, and the openFr

  8. SLED program

    International Nuclear Information System (INIS)

    A FORTRAN program is described which, for a given cavity and timing, yields all fields as a (piecewise) function of time, and which, for any mix of SLEDded and non-SLEDded klystrons of any given energy/klystron, yields the SLED operation parameters. The note explains the input and output parameters as they appear in the code output. 3 figures, 19 tables

  9. ORGEL program

    Energy Technology Data Exchange (ETDEWEB)

    none

    1963-09-01

    Parameter optimization studies for an ORGEL power plant are reported, and the ESSOR test reactor used in the program is described. Research at Ispra in reactor physics, technology, metallurgy, heat transfer, chemistry, and physical chemistry associated with ORGEL development is also summarized. (D.C.W.)

  10. Program overview: Subsurface science program

    International Nuclear Information System (INIS)

    The OHER Subsurface Science Program is DOE's core basic research program concerned with subsoils and groundwater. These practices have resulted in contamination by mixtures of organic chemicals, inorganic chemicals, and radionuclides. A primary long-term goal is to provide a foundation of knowledge that will lead to the reduction of environmental risks and to cost-effective cleanup strategies. Since the Program was initiated in 1985, a substantial amount of research in hydrogeology, subsurface microbiology, and the geochemistry of organically complexed radionuclides has been completed, leading to a better understanding of contaminant transport in groundwater and to new insights into microbial distribution and function in the subsurface environments. The Subsurface Science Program focuses on achieving long-term scientific advances that will assist DOE in the following key areas: providing the scientific basis for innovative in situ remediation technologies that are based on a concept of decontamination through benign manipulation of natural systems; understanding the complex mechanisms and process interactions that occur in the subsurface; determining the influence of chemical and geochemical-microbial processes on co-contaminant mobility to reduce environmental risks; improving predictions of contaminant transport that draw on fundamental knowledge of contaminant behavior in the presence of physical and chemical heterogeneities to improve cleanup effectiveness and to predict environmental risks

  11. Constraint Programming versus Mathematical Programming

    DEFF Research Database (Denmark)

    Hansen, Jesper

    2003-01-01

    Constraint Logic Programming (CLP) is a relatively new technique from the 80's with origins in Computer Science and Artificial Intelligence. Lately, much research have been focused on ways of using CLP within the paradigm of Operations Research (OR) and vice versa. The purpose of this paper...

  12. Linear programming

    CERN Document Server

    Karloff, Howard

    1991-01-01

    To this reviewer’s knowledge, this is the first book accessible to the upper division undergraduate or beginning graduate student that surveys linear programming from the Simplex Method…via the Ellipsoid algorithm to Karmarkar’s algorithm. Moreover, its point of view is algorithmic and thus it provides both a history and a case history of work in complexity theory. The presentation is admirable; Karloff's style is informal (even humorous at times) without sacrificing anything necessary for understanding. Diagrams (including horizontal brackets that group terms) aid in providing clarity. The end-of-chapter notes are helpful...Recommended highly for acquisition, since it is not only a textbook, but can also be used for independent reading and study. —Choice Reviews The reader will be well served by reading the monograph from cover to cover. The author succeeds in providing a concise, readable, understandable introduction to modern linear programming. —Mathematics of Computing This is a textbook intend...

  13. Biological programming

    OpenAIRE

    Ramsden, Jeremy J.; Bándi, Gergely

    2010-01-01

    Biology offers a tremendous set of concepts that are potentially very powerfully usable for the software engineer, but they have been barely exploited hitherto. In this position paper we propose a fresh attempt to create the building blocks of a programming technology that could be as successful as life. A key guiding principle is to develop and make use of unambiguous definitions of the essential features of life.

  14. Program summary

    International Nuclear Information System (INIS)

    The operating, construction, and development activities of the Department of Energy in the areas of uranium enrichment are described. The DOE supplies the enrichment service through toll enrichment contracts with foreign and domestic utilities by enriching uranium supplied by the utility to the desired U-235 level. This role will continue well into the next century. In addition it provides enriched uranium for US Government needs and for R and D purposes. At the present time, almost all the world's capacity to produce enriched uranium uses the gaseous diffusion process. The United States built the first gaseous diffusion plant during World War II. Later this plant was expanded and two additional plants were built. There is presently a $1.5 billion improvement and uprating program near completion which will improve the plant efficiency and increase the total capacity of the three plants by 60 percent to 27.3 million SWU per year. The Administration's energy message in 1977 provided for a further expansion of this capacity by using gas centrifuge technology. The new gas centrifuge plant is being built near the existing GDP near Portsmouth, Ohio. The normal capacity of an 8 building process plant will be 13.2 million SWU per year. The first 2.2 million SWU of capacity is scheduled to be available in 1989. The remaining capacity will be added as needed to meet demand and the overall goal of the program. The goal of the Uranium Enrichment Program is to meet domestic, foreign, and US Government requirements for uranium enrichment services in an economical, reliable, safe and environmentally acceptable manner. To ensure accomplishment of this goal, the overall program is broken down into three areas of implementation; Enrichment Operations; Capacity Upgrading Operations; and Business Operations

  15. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Standards News Cancer Cancer Programs Cancer Programs American Joint Committee on Cancer Cancer Advocacy Efforts Cancer Liaison ... Validation Programs Accredited Education Institutes CME Accreditation CME Joint Providership Program Program for Validation and Verification of ...

  16. Programming Pig

    CERN Document Server

    Gates, Alan

    2011-01-01

    This guide is an ideal learning tool and reference for Apache Pig, the open source engine for executing parallel data flows on Hadoop. With Pig, you can batch-process data without having to create a full-fledged application-making it easy for you to experiment with new datasets. Programming Pig introduces new users to Pig, and provides experienced users with comprehensive coverage on key features such as the Pig Latin scripting language, the Grunt shell, and User Defined Functions (UDFs) for extending Pig. If you need to analyze terabytes of data, this book shows you how to do it efficiently

  17. RADARSAT program

    Science.gov (United States)

    Mcnally, J.; Parashar, S.

    1993-01-01

    Work on the RADARSAT system is progressing towards the currently scheduled launch date of early 1995. The spacecraft bus and the Synthetic Aperture Radar (SAR) payload are at various stages of development. Requirements for the ground segment have been mostly established. The design of the ground elements such as the mission control facility and the SAR data processor is underway. The SAR applications development work is continuing and the chosen distributor, RADARSAT International Inc. (RSI) is making preparations to market RADARSAT data internationally. A plan for the follow-on to RADARSAT 1 is being finalized to ensure continuity of SAR data under the Radarsat program.

  18. Programming Razor

    CERN Document Server

    Chadwick, Jess

    2011-01-01

    Take Razor for a test drive and discover first hand how this scripting syntax simplifies the way you create dynamic, data-driven websites. With this concise guide, you'll work with Razor syntax by building example websites with Microsoft WebMatrix and ASP.NET MVC. You'll quickly learn how Razor lets you combine code and content in a fluid and expressive manner on Windows-based servers. Programming Razor also explores components of the Razor API, and shows you how Razor templates are turned into rendered HTML. By the end of this book, you'll be able to create Razor-based websites with custom

  19. Quantum Predicative Programming

    OpenAIRE

    Tafliovich, Anya; Hehner, E. C. R.

    2006-01-01

    The subject of this work is quantum predicative programming -- the study of developing of programs intended for execution on a quantum computer. We look at programming in the context of formal methods of program development, or programming methodology. Our work is based on probabilistic predicative programming, a recent generalisation of the well-established predicative programming. It supports the style of program development in which each programming step is proven correct as it is made. We...

  20. Telemedicine Program

    Science.gov (United States)

    1996-01-01

    Since the 1970s, NASA has been involved in the research and demonstration of telemedicine for its potential in the care of astronauts in flight and Earth-bound applications. A combination of NASA funding, expertise and off-the-shelf computer and networking systems made telemedicine possible for a medically underserved hospital in Texas. Through two-way audio/video relay, the program links pediatric oncology specialists at the University of Texas Health Science Center in San Antonio to South Texas Hospital in Harlingen, providing easier access and better care to children with cancer. Additionally, the hospital is receiving teleclinics on pediatric oncology nursing, family counseling and tuberculosis treatment. VTEL Corporation, Sprint, and the Healthcare Open Systems and Trials Consortium also contributed staff and hardware.

  1. Apollo Program

    Science.gov (United States)

    1963-01-01

    Construction of the track which runs in front of Model 2. Technicians work on Model 1, the 20-foot sphere. Project LOLA or Lunar Orbit and Landing Approach was a simulator built at Langley to study problems related to landing on the lunar surface. It was a complex project that cost nearly $2 million dollars. James Hansen wrote: 'This simulator was designed to provide a pilot with a detailed visual encounter with the lunar surface; the machine consisted primarily of a cockpit, a closed-circuit TV system, and four large murals or scale models representing portions of the lunar surface as seen from various altitudes. The pilot in the cockpit moved along a track past these murals which would accustom him to the visual cues for controlling a spacecraft in the vicinity of the moon. Unfortunately, such a simulation--although great fun and quite aesthetic--was not helpful because flight in lunar orbit posed no special problems other than the rendezvous with the LEM, which the device did not simulate. Not long after the end of Apollo, the expensive machine was dismantled.' (p. 379) Ellis J. White wrote in his paper 'Discussion of Three Typical Langley Research Center Simulation Programs,' 'The model system is designed so that a television camera is mounted on a camera boom on each transport cart and each cart system is shared by two models. The cart's travel along the tracks represents longitudinal motion along the plane of a nominal orbit, vertical travel of the camera boom represents latitude on out-of-plane travel, and horizontal travel of the camera boom represents altitude changes.' Published in James R. Hansen, Spaceflight Revolution: NASA Langley Research Center From Sputnik to Apollo, NASA SP-4308, p. 379; Ellis J. White, 'Discussion of Three Typical Langley Research Center Simulation Programs,' Paper presented at the Eastern Simulation Council (EAI's Princeton Computation Center), Princeton, NJ, October 20, 1966.

  2. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Base Oncology Medical Home Accreditation Pilot Program Stereotactic Breast Biopsy Accreditation Program Cancer Program Staff Information Surgeon Specific Registry Surgeon Specific ...

  3. Annotated Answer Set Programming

    OpenAIRE

    Straccia, Umberto

    2005-01-01

    We present Annotated Answer Set Programming, that extends the ex pressive power of disjunctive logic programming with annotation terms, taken from the generalized annotated logic programming framework.

  4. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Cancer Liaison Program Commission on Cancer National Cancer Data Base Oncology Medical Home Accreditation Pilot Program Stereotactic ... About Trauma Programs Stop the Bleed National Trauma Data Bank Trauma Quality Improvement Program Mentoring for Excellence ...

  5. Functional Python programming

    CERN Document Server

    Lott, Steven

    2015-01-01

    This book is for developers who want to use Python to write programs that lean heavily on functional programming design patterns. You should be comfortable with Python programming, but no knowledge of functional programming paradigms is needed.

  6. Human Reliability Program Overview

    Energy Technology Data Exchange (ETDEWEB)

    Bodin, Michael

    2012-09-25

    This presentation covers the high points of the Human Reliability Program, including certification/decertification, critical positions, due process, organizational structure, program components, personnel security, an overview of the US DOE reliability program, retirees and academia, and security program integration.

  7. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Program for Breast Centers National Accreditation Program for Breast Centers About NAPBC Accreditation Education Patient Resources Center Resources NAPBC Standards News Cancer Cancer Programs Cancer Programs American Joint Committee on ...

  8. Stop smoking support programs

    Science.gov (United States)

    Smokeless tobacco - stop smoking programs; Stop smoking techniques; Smoking cessation programs; Smoking cessation techniques ... It is hard to quit smoking if you are acting alone. Smokers may have a ... of quitting with a support program. Stop smoking programs ...

  9. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Program Outside Activities Member Communities Military Health System Strategic Partnership ACS Archives Board of Governors Advisory Councils Quality Programs Quality Programs Overview About Quality Programs ACS Leadership in Quality ACS Leadership in Quality Inspiring Quality ...

  10. Nonlinear Programming Method for Dynamic Programming

    OpenAIRE

    Yongyang Cai; Judd, Kenneth L; Lontzek, Thomas S.; Valentina Michelangeli; Che-Lin Su

    2013-01-01

    A nonlinear programming formulation is introduced to solve infinite horizon dynamic programming problems. This extends the linear approach to dynamic programming by using ideas from approximation theory to avoid inefficient discretization. Our numerical results show that this nonlinear programming method is efficient and accurate.

  11. Behavioral program synthesis with genetic programming

    CERN Document Server

    Krawiec, Krzysztof

    2016-01-01

    Genetic programming (GP) is a popular heuristic methodology of program synthesis with origins in evolutionary computation. In this generate-and-test approach, candidate programs are iteratively produced and evaluated. The latter involves running programs on tests, where they exhibit complex behaviors reflected in changes of variables, registers, or memory. That behavior not only ultimately determines program output, but may also reveal its `hidden qualities' and important characteristics of the considered synthesis problem. However, the conventional GP is oblivious to most of that information and usually cares only about the number of tests passed by a program. This `evaluation bottleneck' leaves search algorithm underinformed about the actual and potential qualities of candidate programs. This book proposes behavioral program synthesis, a conceptual framework that opens GP to detailed information on program behavior in order to make program synthesis more efficient. Several existing and novel mechanisms subs...

  12. Purely Functional Structured Programming

    OpenAIRE

    Obua, Steven

    2010-01-01

    The idea of functional programming has played a big role in shaping today's landscape of mainstream programming languages. Another concept that dominates the current programming style is Dijkstra's structured programming. Both concepts have been successfully married, for example in the programming language Scala. This paper proposes how the same can be achieved for structured programming and PURELY functional programming via the notion of LINEAR SCOPE. One advantage of this proposal is that m...

  13. System programming languages

    OpenAIRE

    Šmit, Matej

    2016-01-01

    Most operating systems are written in the C programming language. Similar is with system software, for example, device drivers, compilers, debuggers, disk checkers, etc. Recently some new programming languages emerged, which are supposed to be suitable for system programming. In this thesis we present programming languages D, Go, Nim and Rust. We defined the criteria which are important for deciding whether programming language is suitable for system programming. We examine programming langua...

  14. CFRP strengthened openings in two-way concrete slabs

    DEFF Research Database (Denmark)

    Enochsson, O.; Lundqvist, J.; Täljsten, Björn;

    2006-01-01

    Rehabilitation and strengthening of concrete structures with externally bonded fibre reinforced polymers (FRPs) has been a viable technique for at least a decade. An interesting and useful application is strengthening of slabs or walls where openings are introduced. In these situations, FRP sheet...

  15. Shear Strengthening of Corbels with Carbon Fibre Reinforced Polymers (CFRP)

    OpenAIRE

    Nawaz, A.; Salimullah, K.; Shah, A; Ahmad, S.

    2010-01-01

    Corbels constitute what are known as “disturbed” regions in concrete structures, where typical shear failure may be anticipated on the grounds of small shear span-to-depth ratios. The concentration of stress induced by the weight of girders on the very small loadbearing areas in corbels often causes cracking in bridges and other structures. Little experimental research can be found in the literature on the shear strengthening of corbels. In the present study, nine such members were tested. Tw...

  16. EXTERNAL PRESTRESSING OF RC T-BEAMS WITH CFRP TENDONS

    DEFF Research Database (Denmark)

    Bennitz, Anders; Schmidt, Jacob Wittrup; Täljsten, Björn

    2009-01-01

    stated in [6] and future guidelines, a database of tested structures to compare with is necessary. Such a database is for example used in [7] for verification of FRP shear strengthening models and is in that case composed of more than 200 tested beams with different material and geometrical properties...... ultimate capacity could be increased, with a carefully applied compressive stress existing open cracks in concrete may be partly closed and it might also be possible to reduce large deflections. In that way the durability of the entire RC (Reinforced Concrete) -structure can be increased. Application of...... FRPs as prestressing materials does however require a new design philosophy. FRPs are in contradiction to high strength prestressing steel linearly elastic until failure and they are, in their nature, also generally orthotropic. The behaviour of a RC-structure prestressed with FRP might therefore...

  17. Structured Programming: An Introduction.

    Science.gov (United States)

    Moulton, Peter

    Designed for use by computer programming teachers, this booklet presents the concepts of structured programming and provides examples of how to implement this methodology, which provides a systematic way of organizing programs so that even large and complex programs are easier to understand and modify than unstructured programs. After a brief…

  18. Visual program simulation in introductory programming education

    OpenAIRE

    Sorva, Juha

    2012-01-01

    This thesis formulates and evaluates a pedagogical technique whose goal is to help beginners learn the basics of computer programming. The technique, visual program simulation (VPS), involves the learner in interactive simulations in which the learner takes on the role of the computer as the executor of a program. The student uses a given visualization of a so-called notional machine, an abstract computer, to illustrate what happens in memory as the computer processes the program. The purpose...

  19. Energy Technology Programs: program summaries for 1979

    Energy Technology Data Exchange (ETDEWEB)

    1979-12-01

    The Energy Technology Programs in the BNL Department of Energy and Environment cover a broad range of activities, namely: electrochemical research, chemical energy storage, chemical heat pumps, solar technology, fossil technology, catalytic systems development, space-conditioning technology, and technical support/program management. Summaries of the individual tasks associated with these activities along with publications, significant accomplishments, and program funding levels are presented.

  20. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Accreditation Program for Breast Centers About NAPBC Accreditation Education Patient Resources Center Resources NAPBC Standards News Cancer ... Program for Hospitals Trauma Systems Consultation Program Trauma Education Publications and Posters Injury Prevention and Control Education ...

  1. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Shop/Donate ( 0 ) Items American College of Surgeons Education Patients and Family Skills Programs Ostomy Home Skills Program Ostomy Home Skills Program Adult Ostomy Pediatric Ostomy Programa de Destrezas para manejo ...

  2. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Member Chapter Leader RAS-ACS Leader YFA Leader Leadership & Advocacy Summit Operation Giving Back Operation Giving Back ... Programs Quality Programs Overview About Quality Programs ACS Leadership in Quality ACS Leadership in Quality Inspiring Quality ...

  3. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... ACS Insurance Programs ACS Discount Programs FACS Resources Career Connection Update Your Profile Scholarships, Fellowships, and Awards ... SSC Membership Directory Annual Meeting Mentorship Program Outside Activities Member Communities Military Health System Strategic Partnership ACS ...

  4. Masonry Program Standards.

    Science.gov (United States)

    Georgia Univ., Athens. Dept. of Vocational Education.

    This publication contains statewide standards for the masonry program in Georgia. The standards are divided into 12 categories: foundations (philosophy, purpose, goals, program objectives, availability, evaluation); admissions (admission requirements, provisional admission requirements, recruitment, evaluation and planning); program structure…

  5. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Programs Educational Programs SESAP SESAP Sampler SRGS ACS Fundamentals of Surgery Curriculum Transition to Practice Program ACS/ ... Education Advanced Trauma Life Support Trauma Evaluation and Management Advanced Trauma Operative Management Rural Trauma Team Development ...

  6. Quantum Predicative Programming

    CERN Document Server

    Tafliovich, A; Tafliovich, Anya

    2006-01-01

    The subject of this work is quantum predicative programming -- the study of developing of programs intended for execution on a quantum computer. We look at programming in the context of formal methods of program development, or programming methodology. Our work is based on probabilistic predicative programming, a recent generalisation of the well-established predicative programming. It supports the style of program development in which each programming step is proven correct as it is made. We inherit the advantages of the theory, such as its generality, simple treatment of recursive programs, time and space complexity, and communication. Our theory of quantum programming provides tools to write both classical and quantum specifications, develop quantum programs that implement these specifications, and reason about their comparative time and space complexity all in the same framework.

  7. [Theme: Horticulture Programs.

    Science.gov (United States)

    Henderson, Jan; And Others

    1982-01-01

    A series of articles discusses requirements for optimum growth of horticulture education programs. Includes beginning a program, simulating working conditions, the need for mechanical skills, starting a business, and other areas to be considered for a successful horticultural program. (JOW)

  8. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Verification, Review, and Consultation Program for Hospitals Trauma Systems Consultation Program Trauma Education Publications and Posters Injury Prevention and Control Education ...

  9. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Project Team Resources News Contact Us ACS NSQIP Pediatric ACS National Surgical Quality Improvement Program Pediatric ACS National Surgical Quality Improvement Program Pediatric About ...

  10. Developing Parallel Programs

    OpenAIRE

    Ranjan Sen

    2012-01-01

    Parallel programming is an extension of sequential programming; today, it is becoming the mainstream paradigm in day-to-day information processing. Its aim is to build the fastest programs on parallel computers. The methodologies for developing a parallelprogram can be put into integrated frameworks. Development focuses on algorithm, languages, and how the program is deployed on the parallel computer.

  11. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Quality Reporting System MOC Part 4 and Recertification Software and Registration SSR Webinars SSR Login Trauma Trauma Programs Trauma Programs About Trauma Programs Stop the Bleed National Trauma Data Bank Trauma Quality Improvement Program Mentoring for Excellence in Trauma Surgery Advanced ...

  12. National Transuranic Program Charter

    International Nuclear Information System (INIS)

    The National Transuranic Program Plan and Charter describes the functional elements of the National TRU Program, organizational relationships, programmatic responsibilities, division of work scope among the various DOE organizations that comprise the program, and program baselines against which overall progress will be measured. The charter defines the authorities and responsibilities of various organizations involved in the management of TRU waste throughout the DOE complex

  13. Laser Programs Highlights 1998

    Energy Technology Data Exchange (ETDEWEB)

    Lowdermilk, H.; Cassady, C.

    1999-12-01

    This report covers the following topics: Commentary; Laser Programs; Inertial Confinement Fusion/National Ignition Facility (ICF/NIF); Atomic Vapor Laser Isotope Separation (AVLIS); Laser Science and Technology (LS&T); Information Science and Technology Program (IS&T); Strategic Materials Applications Program (SMAP); Medical Technology Program (MTP) and Awards.

  14. [PIC Program Evaluation Forms.

    Science.gov (United States)

    Short, N. J.

    These 4 questionnaires are designed to elicit teacher and parent evaluations of the Prescriptive Instruction Center (PIC) program. Included are Teacher Evaluation of Program Effectiveness (14 items), M & M Evaluation of Program Implementation (methods and materials specialists; 11 items), Teacher Evaluation of Program Effectiveness--Case Study…

  15. The Cybernetic Writing Program.

    Science.gov (United States)

    Lowe, Kelly Fisher

    This paper looks at the role of a Writing Program Administrator, and applies the idea of a cybernetic system to the administration of the program. In this cybernetic model, the Writing Program Administrator (WPA) works as both a problem solver and problem causer, with the responsibility of keeping the program in proper balance. A cybernetic…

  16. Derivation of sorting programs

    Science.gov (United States)

    Varghese, Joseph; Loganantharaj, Rasiah

    1990-01-01

    Program synthesis for critical applications has become a viable alternative to program verification. Nested resolution and its extension are used to synthesize a set of sorting programs from their first order logic specifications. A set of sorting programs, such as, naive sort, merge sort, and insertion sort, were successfully synthesized starting from the same set of specifications.

  17. Light water reactor program

    Energy Technology Data Exchange (ETDEWEB)

    Franks, S.M.

    1994-12-31

    The US Department of Energy`s Light Water Reactor Program is outlined. The scope of the program consists of: design certification of evolutionary plants; design, development, and design certification of simplified passive plants; first-of-a-kind engineering to achieve commercial standardization; plant lifetime improvement; and advanced reactor severe accident program. These program activities of the Office of Nuclear Energy are discussed.

  18. C++ Programming Language

    Science.gov (United States)

    Shaykhian, Gholam Ali

    2007-01-01

    C++ Programming Language: The C++ seminar covers the fundamentals of C++ programming language. The C++ fundamentals are grouped into three parts where each part includes both concept and programming examples aimed at for hands-on practice. The first part covers the functional aspect of C++ programming language with emphasis on function parameters and efficient memory utilization. The second part covers the essential framework of C++ programming language, the object-oriented aspects. Information necessary to evaluate various features of object-oriented programming; including encapsulation, polymorphism and inheritance will be discussed. The last part of the seminar covers template and generic programming. Examples include both user defined and standard templates.

  19. Federal Wind Energy Program. Program summary. [USA

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-01-01

    The objective of the Federal Wind Energy Program is to accelerate the development of reliable and economically viable wind energy systems and enable the earliest possible commercialization of wind power. To achieve this objective for small and large wind systems requires advancing the technology, developing a sound industrial technology base, and addressing the non-technological issues which could deter the use of wind energy. This summary report outlines the projects being supported by the program through FY 1977 toward the achievement of these goals. It also outlines the program's general organization and specific program elements.

  20. Generating Consistent Program Tutorials

    DEFF Research Database (Denmark)

    Vestdam, Thomas

    In this paper we present a tool that supports construction of program tutorials. A program tutorial provides the reader with an understanding of an example program by interleaving fragments of source code and explaining text. An example program can for example illustrate how to use a library or a...... framework. We present a means for specifying the fragments of a program that are to be in-lined in the tutorial text. These in-line fragments are defined by addressing named syntactical elements, such as classes and methods, but it is also possible to address individual code lines by labeling them with...... source markers. The tool helps ensuring consistency between program tutorial and example programs by extracting fragments of source code based on the fragment specifications and by detecting when a program tutorial is addressing program fragments that do not exist. The program tutorials are presented as...

  1. Purely Functional Structured Programming

    CERN Document Server

    Obua, Steven

    2010-01-01

    The idea of functional programming has played a big role in shaping today's landscape of mainstream programming languages. Another concept that dominates the current programming style is Dijkstra's structured programming. Both concepts have been successfully married, for example in the programming language Scala. This paper proposes how the same can be achieved for structured programming and PURELY functional programming via the notion of LINEAR SCOPE. One advantage of this proposal is that mainstream programmers can reap the benefits of purely functional programming like easily exploitable parallelism while using familiar structured programming syntax and without knowing concepts like monads. A second advantage is that professional purely functional programmers can often avoid hard to read functional code by using structured programming syntax that is often easier to parse mentally.

  2. On Constraint Programming

    OpenAIRE

    Mathieu, Philippe; Keisu, Torbjörn

    1990-01-01

    This short note aims to present foundations for constraint logic programming. By logic programming, we understand in this paper the PROLOG paradigm. But it will be clear that we do reduce the problem to adding a new package to PROLOG. We argue that constraint logic programming should be defined as a new paradigm for programming: the LOGIC PROGRAMMING + SYMBOLIC COMPUTATION paradigm. Our system incorporates as a very basic, all the existing systems incorporating constraints i...

  3. Computer assisted mathematical programming

    OpenAIRE

    Lucas, CA; Mitra, G

    1987-01-01

    A Computer Assisted Mathematical Programming (Modelling) System (CAMPS) is described in this paper. The system uses program generator techniques for model creation and contrasts with earlier approaches which use a special purpose language to construct models. Thus no programming skill is required to formulate a model. In designing the system we have first analysed the salient components of the mathematical programming activity. A mathematical programming model is usually constructed by progre...

  4. Technology Commercialization Program 1991

    Energy Technology Data Exchange (ETDEWEB)

    1991-11-01

    This reference compilation describes the Technology Commercialization Program of the Department of Energy, Defense Programs. The compilation consists of two sections. Section 1, Plans and Procedures, describes the plans and procedures of the Defense Programs Technology Commercialization Program. The second section, Legislation and Policy, identifies legislation and policy related to the Program. The procedures for implementing statutory and regulatory requirements are evolving with time. This document will be periodically updated to reflect changes and new material.

  5. Learning programming: treasure hunt

    OpenAIRE

    Močnik, Mariza

    2015-01-01

    In this thesis a few teoretical basics about computational and algoritmic thinking are given, which is necessary in programming. Programming allows developing of new programs, which are constantly needed in all areas. Early learning is therfore significant for children and their future. Among modern ways of teaching programming belongs game palying, for this purpose an example board game is presented The game is called "Lov na zaklad". It was created using graphical programs and few websit...

  6. Teaching Programming with Scratch

    OpenAIRE

    Mihalič, Petra

    2014-01-01

    There are quite a few good programing languages and environments for teaching kids how to program. They help beginners learn basic programming constructs usually with help of interactive environment. In this thesis I will describe and compare a few of those languages and environments. Scratch is a language and programming environment that is also intended for learning programming using blocks that make writing complicated instructions easier and reduce beginners' difficulties with syntax erro...

  7. Multiobjective programming and planning

    CERN Document Server

    Cohon, Jared L

    2004-01-01

    This text takes a broad view of multiobjective programming, emphasizing the methods most useful for continuous problems. It reviews multiobjective programming methods in the context of public decision-making problems, developing each problem within a context that addresses practical aspects of planning issues. Topics include a review of linear programming, the formulation of the general multiobjective programming problem, classification of multiobjective programming methods, techniques for generating noninferior solutions, multiple-decision-making methods, multiobjective analysis of water reso

  8. Programming with joystick

    OpenAIRE

    Banič, Nejc

    2014-01-01

    In this thesis, we implemented a way of programming by means of gaming accessories. The main reason is that to show a diferent way of developing programs, because vast majority of programers are using two input / output devices: keyboard and mouse. These two devices have become standard and will definitely remain so in the future. For our implementation, we used high-level programming language Java and NetBeans integrated development environment. The program is actually a ...

  9. Introduction to relational programming

    OpenAIRE

    MacLennan, Bruce J.

    2013-01-01

    A new method of programming, called relational programming, is introduced. This is a style of programming in which entire relations are manipulated rather than individual data. This is analogous to functional programming, wherein entire functions are the value manipulated by the operators. Because of its ability to manipulate complex data structures other than lists, relational programming seems to have distinct advantages over other very high level languages. This paper introduces the basic ...

  10. Introduction to parallel programming

    CERN Document Server

    Brawer, Steven

    1989-01-01

    Introduction to Parallel Programming focuses on the techniques, processes, methodologies, and approaches involved in parallel programming. The book first offers information on Fortran, hardware and operating system models, and processes, shared memory, and simple parallel programs. Discussions focus on processes and processors, joining processes, shared memory, time-sharing with multiple processors, hardware, loops, passing arguments in function/subroutine calls, program structure, and arithmetic expressions. The text then elaborates on basic parallel programming techniques, barriers and race

  11. Submicron Composite Mirror Replication (PDRT08-027) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR program will identify and address the primary technical issues that limit the current precision of replicated CFRP optics. These issues must be resolved...

  12. Traditional Planetarium Programming versus Participatory Planetarium Programming.

    Science.gov (United States)

    Fletcher, Jack K.

    1980-01-01

    The results of this study indicate that, for the astronomical concepts used, no significant difference in the cognitive domain will occur between the achievement of students who experience a participatory planetarium program and students who experience a traditional lecture-demonstration program. (Author/MK)

  13. Analyzing Array Manipulating Programs by Program Transformation

    Science.gov (United States)

    Cornish, J. Robert M.; Gange, Graeme; Navas, Jorge A.; Schachte, Peter; Sondergaard, Harald; Stuckey, Peter J.

    2014-01-01

    We explore a transformational approach to the problem of verifying simple array-manipulating programs. Traditionally, verification of such programs requires intricate analysis machinery to reason with universally quantified statements about symbolic array segments, such as "every data item stored in the segment A[i] to A[j] is equal to the corresponding item stored in the segment B[i] to B[j]." We define a simple abstract machine which allows for set-valued variables and we show how to translate programs with array operations to array-free code for this machine. For the purpose of program analysis, the translated program remains faithful to the semantics of array manipulation. Based on our implementation in LLVM, we evaluate the approach with respect to its ability to extract useful invariants and the cost in terms of code size.

  14. Programming Models in HPC

    Energy Technology Data Exchange (ETDEWEB)

    Shipman, Galen M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-13

    These are the slides for a presentation on programming models in HPC, at the Los Alamos National Laboratory's Parallel Computing Summer School. The following topics are covered: Flynn's Taxonomy of computer architectures; single instruction single data; single instruction multiple data; multiple instruction multiple data; address space organization; definition of Trinity (Intel Xeon-Phi is a MIMD architecture); single program multiple data; multiple program multiple data; ExMatEx workflow overview; definition of a programming model, programming languages, runtime systems; programming model and environments; MPI (Message Passing Interface); OpenMP; Kokkos (Performance Portable Thread-Parallel Programming Model); Kokkos abstractions, patterns, policies, and spaces; RAJA, a systematic approach to node-level portability and tuning; overview of the Legion Programming Model; mapping tasks and data to hardware resources; interoperability: supporting task-level models; Legion S3D execution and performance details; workflow, integration of external resources into the programming model.

  15. TFE verification program

    Science.gov (United States)

    1990-03-01

    The information presented herein will include evaluated test data, design evaluations, the results of analyses and the significance of results. The program objective is to demonstrate the technology readiness of a Thermionic Fuel Element (TFE) suitable for use as the basic element in a thermionic reactor with electric power output in the 0.5 to 5.0 MW(e) range, and a full-power life of 7 years. The TF Verification Program builds directly on the technology and data base developed in the 1960s and 1970s in an AEC/NASA program, and in the SP-100 program conducted in 1983, 1984 and 1985. In the SP-100 program, the attractive features of thermionic power conversion technology were recognized but concern was expressed over the lack of fast reactor irradiation data. The TFE Verification Program addresses this concern. The general logic and strategy of the program to achieve its objectives is shown. Five prior programs form the basis for the TFE Verification Program: (1) AEC/NASA program of the 1960s and early 1970; (2) SP-100 concept development program; (3) SP-100 thermionic technology program; (4) Thermionic irradiations program in TRIGA in FY-88; and (5) Thermionic Program in 1986 and 1987.

  16. The CHROME Honors Program

    Science.gov (United States)

    Wilson, Eleanor

    2002-01-01

    The CHROME Honors Program was designed as a two-week residential program for 9th and 1Oth grade students participating in CHROME clubs. The curriculum focused on the health sciences with instruction from: (1) the science and health curriculum of the Dozoretz National Program for Minorities in Applied Sciences (DNIMAS) Program of Norfolk State University (NSU); (2) the humanities curriculum of the NSU Honors Program; (3) NASA-related curriculum in human physiology. An Advisory Committee was formed to work with the Project Coordinator in the design of the summer program.

  17. Revealing the programming process

    DEFF Research Database (Denmark)

    Bennedsen, Jens; Caspersen, Michael Edelgaard

    2005-01-01

    One of the most important goals of an introductory programming course is that the students learn a systematic approach to the development of computer programs. Revealing the programming process is an important part of this; however, textbooks do not address the issue -- probably because...... the textbook medium is static and therefore ill-suited to expose the process of programming. We have found that process recordings in the form of captured narrated programming sessions are a simple, cheap, and efficient way of providing the revelation.We identify seven different elements of the programming...

  18. Veterans Choice Program

    Data.gov (United States)

    Department of Veterans Affairs — If you are already enrolled in VA health care, the Choice Program allows you to receive health care within your community. Using this program does NOT impact your...

  19. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... and Canada) International Fellows Associate Fellows Residents Medical Students Affiliate Members Fees and Dues Member Benefits About ... and Canada) International Fellows Associate Fellows Residents Medical Students Affiliate Members ACS Insurance Programs ACS Discount Programs ...

  20. HUD Program Income Limits

    Data.gov (United States)

    Department of Housing and Urban Development — Income limits used to determine the income eligibility of applicants for assistance under three programs authorized by the National Housing Act. These programs are...

  1. Materials Sciences Programs

    International Nuclear Information System (INIS)

    A compilation and index of the ERDA materials sciences program is presented. This compilation is intended for use by administrators, managers, and scientists to help coordinate research and as an aid in selecting new programs

  2. Materials Sciences Programs

    Energy Technology Data Exchange (ETDEWEB)

    1977-01-01

    A compilation and index of the ERDA materials sciences program is presented. This compilation is intended for use by administrators, managers, and scientists to help coordinate research and as an aid in selecting new programs. (GHT)

  3. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Health System Strategic Partnership ACS Archives Board of Governors Advisory Councils Quality Programs Quality Programs Overview About ... FAQs Newsletters Newsletters Overview Newsletters Overview Board of Governors News The CoC Source Committee on Trauma News ...

  4. Parallel programming with PCN

    Energy Technology Data Exchange (ETDEWEB)

    Foster, I.; Tuecke, S.

    1991-12-01

    PCN is a system for developing and executing parallel programs. It comprises a high-level programming language, tools for developing and debugging programs in this language, and interfaces to Fortran and C that allow the reuse of existing code in multilingual parallel programs. Programs developed using PCN are portable across many different workstations, networks, and parallel computers. This document provides all the information required to develop parallel programs with the PCN programming system. In includes both tutorial and reference material. It also presents the basic concepts that underly PCN, particularly where these are likely to be unfamiliar to the reader, and provides pointers to other documentation on the PCN language, programming techniques, and tools. PCN is in the public domain. The latest version of both the software and this manual can be obtained by anonymous FTP from Argonne National Laboratory in the directory pub/pcn at info.mcs.anl.gov (c.f. Appendix A).

  5. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Communities Military Health System Strategic Partnership ACS Archives Board of Governors Advisory Councils Quality Programs Quality Programs ... Contact and FAQs Newsletters Newsletters Overview Newsletters Overview Board of Governors News The CoC Source Committee on ...

  6. Entrez Programming Utilities

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Entrez Programming Utilities (E-utilities) are a set of eight server-side programs that provide a stable interface into the Entrez query and database system at...

  7. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Medical Professionals Skills Programs Find a Treatment Center Patient Safety Resources About the Patient Education Program The Recovery ... Trauma CME Nora Institute Nora Institute for Surgical Patient Safety Nora Institute for Surgical Patient Safety Advanced Skills ...

  8. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... with quality, comprehensive education. The standardized interactive program has been developed by the American College of Surgeons ( ... Hospital Quality Improvement Package The standardized interactive program has been developed by the American College of Surgeons ( ...

  9. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... and Canada) International Fellows Associate Fellows Residents Medical Students Affiliate Members ACS Insurance Programs ACS Discount Programs FACS Resources Career Connection Update Your Profile Scholarships, Fellowships, and Awards ...

  10. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Stereotactic Breast Biopsy Accreditation Program Cancer Program Staff Information Surgeon Specific Registry Surgeon Specific Registry Surgeon Specific Registry Features of the SSR CMS Physician Quality Reporting System MOC Part 4 and Recertification Software and Registration ...

  11. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Other Publications Surgery Workforce Policy Program Current Projects Journal Publications from Surgery Workforce Policy Program AMA House ... the ACS Catalog Find a Product Contribute Education Journal of the American College of Surgeons About JACS ...

  12. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Services Jobs Events Find a Surgeon Patients and Family Contact My Profile Shop/Donate ( 0 ) Items American College of Surgeons Education Patients and Family Skills Programs Ostomy Home Skills Program Ostomy Home ...

  13. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Directory Annual Meeting Mentorship Program Outside Activities Member Communities Military Health System Strategic Partnership ACS Archives Board ... SRGS ACS Fundamentals of Surgery Curriculum Transition to Practice Program ACS/APDS Surgery Resident Skills Curriculum ACS/ ...

  14. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Regulatory Issues How to Avoid Medicare Penalties EHR Incentive Program Medicare Inpatient & Outpatient Rules Physician Quality Reporting ... and Resource Use Reports Electronic Health Records (EHR) Incentive Program Physician Compare Website Surgical Quality Alliance S-CAHPS ...

  15. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... ACS NSQIP Now Participants Downloads Newsroom Contact Us Hospital Compare Educational Events Registry Login SCR Training and ... Life Support Verification, Review, and Consultation Program for Hospitals Trauma Systems Consultation Program Trauma Education Publications and ...

  16. Modeling EERE deployment programs

    Energy Technology Data Exchange (ETDEWEB)

    Cort, K. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hostick, D. J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Belzer, D. B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Livingston, O. V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2007-11-01

    The purpose of the project was to identify and characterize the modeling of deployment programs within the EERE Technology Development (TD) programs, address possible improvements to the modeling process, and note gaps in knowledge for future research.

  17. Diabetes Prevention Program (DPP)

    Science.gov (United States)

    ... Patients & Families Consortia, Networks & Centers Reports & Planning Diabetes Prevention Program (DPP) Page Content On this page: DPP ... to Remember Hope through Research Availability The Diabetes Prevention Program (DPP) was a major multicenter clinical research ...

  18. Youth Suicide Prevention Programs

    Science.gov (United States)

    Kalafat, John

    2006-01-01

    Youth suicide prevention programs are described that promote the identification and referral of at-risk youth, address risk factors, and promote protective factors. Emphasis is on programs that are both effective and sustainable in applied settings.

  19. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Professionals Skills Programs Find a Treatment Center Patient Safety Resources About the Patient Education Program The Recovery ... CME Nora Institute Nora Institute for Surgical Patient Safety Nora Institute for Surgical Patient Safety Advanced Skills ...

  20. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Education ACS Clinical Scholars in Residence Clinical Trials Methods Course Outcomes Research Course Surgeon Specific Registry NSQIP ... Organizations Other Publications Surgery Workforce Policy Program Current Projects Journal Publications from Surgery Workforce Policy Program AMA ...

  1. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Stop the Bleed National Trauma Data Bank Trauma Quality Improvement Program Mentoring for Excellence in Trauma Surgery Advanced Trauma Life Support Verification, Review, and Consultation Program for Hospitals ...

  2. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... of the College Regent Governor Advisory Council Member Committee Member Chapter Leader RAS-ACS Leader YFA Leader ... Communities Military Health System Strategic Partnership ACS Archives Board of Governors Advisory Councils Quality Programs Quality Programs ...

  3. USEPA Arsenic Demonstration Program

    Science.gov (United States)

    The presentation provides background information on the USEPA arsenic removal program. The summary includes information on the history of the program, sites and technology selected, and a summary of the data collected from two completed projects.

  4. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Program Top 10 Reasons to Participate Resources YFA E-News Resident and Associate Society Resident and Associate ... Webinars Membership International Exchange Scholar Program Resources RAS E-News Operation Giving Back Operation Giving Back Operation ...

  5. LOADING SIMULATION PROGRAM C

    Data.gov (United States)

    U.S. Environmental Protection Agency — LSPC is the Loading Simulation Program in C++, a watershed modeling system that includes streamlined Hydrologic Simulation Program Fortran (HSPF) algorithms for...

  6. Transplant Program Reports

    Science.gov (United States)

    ... Find a Transplant Center The SRTR transplant program reports include: Reliable transplant information for patients, families, and ... statistics To retrieve the most recent transplant program reports, please click on an organ type in the ...

  7. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Program Program for Validation and Verification of Surgical Knowledge and Skills Resources Educational Resources Educational Resources E- ... Education Advanced Trauma Life Support Trauma Evaluation and Management Advanced Trauma Operative Management Rural Trauma Team Development ...

  8. Python to learn programming

    Science.gov (United States)

    Bogdanchikov, A.; Zhaparov, M.; Suliyev, R.

    2013-04-01

    Today we have a lot of programming languages that can realize our needs, but the most important question is how to teach programming to beginner students. In this paper we suggest using Python for this purpose, because it is a programming language that has neatly organized syntax and powerful tools to solve any task. Moreover it is very close to simple math thinking. Python is chosen as a primary programming language for freshmen in most of leading universities. Writing code in python is easy. In this paper we give some examples of program codes written in Java, C++ and Python language, and we make a comparison between them. Firstly, this paper proposes advantages of Python language in relation to C++ and JAVA. Then it shows the results of a comparison of short program codes written in three different languages, followed by a discussion on how students understand programming. Finally experimental results of students' success in programming courses are shown.

  9. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Programs Phases of Surgical Care Physician Quality Reporting System Value-Based Payment Modifier Quality and Resource Use Reports Electronic Health Records (EHR) Incentive Program Physician Compare Website Surgical Quality ...

  10. Kickstarting Choreographic Programming

    OpenAIRE

    Montesi, Fabrizio

    2015-01-01

    We present an overview of some recent efforts aimed at the development of Choreographic Programming, a programming paradigm for the production of concurrent software that is guaranteed to be correct by construction from global descriptions of communication behaviour.

  11. ICASE Computer Science Program

    Science.gov (United States)

    1985-01-01

    The Institute for Computer Applications in Science and Engineering computer science program is discussed in outline form. Information is given on such topics as problem decomposition, algorithm development, programming languages, and parallel architectures.

  12. French plutonium management program

    International Nuclear Information System (INIS)

    The French plutonium management program is summarized in this paper. The program considers nuclear generation as a major component of national electric power supply and includes the reprocessing of the spent fuel. (author)

  13. Crab Rationalization Permit Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Crab Rationalization Program (Program) allocates BSAI crab resources among harvesters, processors, and coastal communities. The North Pacific Fishery Management...

  14. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Associate Fellows Residents Medical Students Affiliate Members ACS Insurance Programs ACS Discount Programs FACS Resources Career Connection ... Advocacy Overview Federal Legislation Federal Legislation Federal Legislation Medicare Physician Payment Medical Liability Reform GME and Workforce ...

  15. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Day Grant Program State Legislation Tracked by the College Quality Quality Quality Overview of Medicare Quality Programs ... Input Participate Get Involved Get Involved SurgeonsVoice American College of Surgeons Professional Association State Legislative Action Center ...

  16. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... ACS Insurance Programs ACS Discount Programs FACS Resources Career Connection Update Your Profile Scholarships, Fellowships, and Awards ... Management Advanced Trauma Operative Management Rural Trauma Team Development Course Disaster Management and Emergency Preparedness Advanced Surgical ...

  17. Skeletal parallel programming

    OpenAIRE

    Saez, Fernando; Printista, Alicia Marcela; Piccoli, María Fabiana

    2007-01-01

    In the last time the high-performance programming community has worked to look for new templates or skeletons for several parallel programming paradigms. This new form of programming allows to programmer to reduce the time of development, since it saves time in the phase of design, testing and codification. We are concerned in some issues of skeletons that are fundamental to the definition of any skeletal parallel programming system. This paper present commentaries about these issues in the c...

  18. Towards Applicative Relational Programming

    OpenAIRE

    Ibrahim, H.; van Emden, M. H.

    2006-01-01

    Functional programming comes in two flavours: one where ``functions are first-class citizens'' (we call this applicative) and one which is based on equations (we call this declarative). In relational programming clauses play the role of equations. Hence Prolog is declarative. The purpose of this paper is to provide in relational programming a mathematical basis for the relational analog of applicative functional programming. We use the cylindric semantics of first-order logic due to Tarski an...

  19. Learning Probabilistic Programs

    OpenAIRE

    Perov, Yura N.; Wood, Frank D.

    2014-01-01

    We develop a technique for generalising from data in which models are samplers represented as program text. We establish encouraging empirical results that suggest that Markov chain Monte Carlo probabilistic programming inference techniques coupled with higher-order probabilistic programming languages are now sufficiently powerful to enable successful inference of this kind in nontrivial domains. We also introduce a new notion of probabilistic program compilation and show how the same machine...

  20. MESOT Fellowship Program

    OpenAIRE

    Bassam Saeed

    2011-01-01

    MESOT Fellowship Program (MFP) is an initiative aimed at promoting and advancing organ transplantation in under-served areas of the Middle East by helping them to establish local transplantation programs or to improve an existing program. The fel¬lowship program gives a great opportunity to the young physicians and surgeons from this region willing to acquire some particular skills related to various aspects of organ transplantation and provides them with specific and hands-on training opport...

  1. Photovoltaic systems. Program summary

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-12-01

    Each of the Department of Energy's Photovoltaic Systems Program projects funded and/or in existence during fiscal year 1978 (October 1, 1977 through September 30, 1978) are described. The project sheets list the contractor, principal investigator, and contract number and funding and summarize the programs and status. The program is divided into various elements: program assessment and integration, research and advanced development, technology development, system definition and development, system application experiments, and standards and performance criteria. (WHK)

  2. Probabilistic programming (ECAI tutorial)

    OpenAIRE

    De Raedt, Luc; Kimmig, Angelika

    2014-01-01

    Probabilistic programming is an emerging subfield of AI that extends traditional programming languages with primitives to support probabilistic inference and learning. It is closely related to statistical relational learning, but focuses on a programming language perspective rather than on a graphical model one. This tutorial provides a gentle and coherent introduction to the field by introducing a number of core probabilistic programming concepts and their relations. It focuses on probab...

  3. Probabilistic logic programming

    OpenAIRE

    Kimmig, Angelika

    2014-01-01

    Probabilistic programming is an emerging subfield of AI that extends traditional programming languages with primitives to support probabilistic inference and learning. It is closely related to statistical relational learning, but focuses on a programming language perspective rather than on a graphical model one. This talk provides a gentle and coherent introduction to the field by introducing a number of core probabilistic programming concepts and their relations. It focuses on probabilistic ...

  4. The robot programming network

    OpenAIRE

    Cervera Mateu, Enric; Martinet, Philippe; Marín Prades, Raúl; Moughlbay, Amine A.; Pascual del Pobil Ferré, Ángel; Alemany, Jaime; Esteller Curto, Roger; Casañ Núñez, Gustavo Adolfo

    2016-01-01

    The Robot Programming Network (RPN) is an initiative for creating a network of robotics education laboratories with remote programming capabilities. It consists of both online open course materials and online servers that are ready to execute and test the programs written by remote students. Online materials include introductory course modules on robot programming, mobile robotics and humanoids, aimed to learn from basic concepts in science, technology, engineering, and math...

  5. Special Milk Program

    Science.gov (United States)

    US Department of Agriculture, 2009

    2009-01-01

    The Special Milk Program provides milk to children in schools, child care institutions and eligible camps that do not participate in other Federal child nutrition meal service programs. The program reimburses schools and institutions for the milk they serve. In 2008, 4,676 schools and residential child care institutions participated, along with…

  6. Language Program Evaluation

    Science.gov (United States)

    Norris, John M.

    2016-01-01

    Language program evaluation is a pragmatic mode of inquiry that illuminates the complex nature of language-related interventions of various kinds, the factors that foster or constrain them, and the consequences that ensue. Program evaluation enables a variety of evidence-based decisions and actions, from designing programs and implementing…

  7. PLS Program and Documentation

    Science.gov (United States)

    This program for discriminant analysis using SAS Partial Least Squares (PLS) has been developed as a major modification of a previously published SAS program for quantitative analysis using PLS which is available at http://www.nirpublications.com/software/index.html. That program implemented multip...

  8. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Member Chapter Leader RAS-ACS Leader YFA Leader Leadership & Advocacy Summit Operation Giving Back Operation Giving Back Operation Giving Back About OGB Opportunities Resources and Toolkits ... Quality Programs Quality Programs Overview About Quality Programs ACS Leadership in Quality ACS Leadership in Quality Inspiring Quality ...

  9. Programming the BBC micro

    CERN Document Server

    Ferguson, John D; Macari, Louie; Williams, Peter H

    1983-01-01

    Programming the BBC Micro is a 12-chapter book that begins with a description of the BBC microcomputer, its peripheral, and faults. Subsequent chapters focus on practice in programming, program development, graphics, words, numbers, sound, bits, bytes, and assembly language. The interfacing, file handling, and detailed description of BBC microcomputer are also shown.

  10. Honors Scholar Program.

    Science.gov (United States)

    Lehner, Margaret

    A proposal is presented for an Honors Scholar Program at Moraine Valley Community College in response to the need to provide gifted students with the extra challenges they seek. After providing a rationale for the program, the membership of the steering committee and curriculum committees that would develop and guide the program is designated.…

  11. Masonry Program Guide.

    Science.gov (United States)

    Georgia Univ., Athens. Dept. of Vocational Education.

    This masonry program guide presents the standard curriculum for technical institutes in Georgia. The curriculum addresses the minimum competencies for a masonry program. The general information section contains the following: purpose and objectives; program description, including admissions, typical job titles, and accreditation and certification;…

  12. The Zero Program

    Science.gov (United States)

    Roland, Erling; Midthassel, Unni Vere

    2012-01-01

    Zero is a schoolwide antibullying program developed by the Centre for Behavioural Research at the University of Stavanger, Norway. It is based on three main principles: a zero vision of bullying, collective commitment among all employees at the school using the program, and continuing work. Based on these principles, the program aims to reduce…

  13. The School Breakfast Program

    Science.gov (United States)

    US Department of Agriculture, 2009

    2009-01-01

    The School Breakfast Program is a federally assisted meal program operating in public and nonprofit private schools and residential child care institutions. It began as a pilot project in 1966, and was made permanent in 1975. The School Breakfast Program is administered at the Federal level by the Food and Nutrition Service. At the State level,…

  14. Dropout Retrieval Programs.

    Science.gov (United States)

    Salerno, Anne; Fink, Mary

    This paper describes 15 dropout retrieval programs that have components with potential for helping migrant dropout youth return to an educational program. Each profile contains information on eligibility, identification or recruitment method, funding, services, and contacts. In addition, each program is categorized as to type of sponsoring…

  15. Customer Service Programming

    Science.gov (United States)

    1982-01-01

    Use of computer program STRCMACS has enabled Illinois Bell Telephone, a subsidiary of American Telephone and Telegraph to cut software development costs about 10 percent by reducing program maintenance and by allowing the department to bring other software into operation more quickly. It has also been useful in company training of programming staff.

  16. Modern programming language

    Science.gov (United States)

    Feldman, G. H.; Johnson, J. A.

    1980-01-01

    Structural-programming language is especially-tailored for producing assembly language programs for MODCOMP II and IV mini-computes. Modern programming language consists of set of simple and powerful control structures that include sequencing alternative selection, looping, sub-module linking, comment insertion, statement continuation, and compilation termination capabilities.

  17. Weatherization and Intergovernmental Program - Weatherization Assistance Program

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-06-01

    The U.S. Department of Energy’s (DOE) Weatherization Assistance Program reduces energy costs for low-income households by increasing the energy efficiency of their homes, while ensuring their health and safety.

  18. Wind Energy Program: Top 10 Program Accomplishments

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-01-18

    Brochure on the top accomplishments of the Wind Energy Program, including the development of large wind machines, small machines for the residential market, wind tunnel testing, computer codes for modeling wind systems, high definition wind maps, and successful collaborations.

  19. Equipment qualification research program: program plan

    International Nuclear Information System (INIS)

    The Lawrence Livermore National Laboratory (LLNL) under the sponsorship of the US Nuclear Regulatory Commission (NRC) has developed this program plan for research in equipment qualification (EQA). In this report the research program which will be executed in accordance with this plan will be referred to as the Equipment Qualification Research Program (EQRP). Covered are electrical and mechanical equipment under the conditions described in the OBJECTIVE section of this report. The EQRP has two phases; Phase I is primarily to produce early results and to develop information for Phase II. Phase I will last 18 months and consists of six projects. The first project is program management. The second project is responsible for in-depth evaluation and review of EQ issues and EQ processes. The third project is responsible for detailed planning to initiate Phase II. The remaining three projects address specific equipment; i.e., valves, electrical equipment, and a pump

  20. Scallop License Limitation Program (SLLP) Permit Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A federal Scallop License Limitation Program (SLLP) license is required onboard any vessel deployed in scallop fisheries in Federal waters off Alaska (except for...

  1. Clean Coal Technology Programs: Program Update 2009

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-10-01

    The purpose of the Clean Coal Technology Programs: Program Update 2009 is to provide an updated status of the U.S. Department of Energy (DOE) commercial-scale demonstrations of clean coal technologies (CCT). These demonstrations have been performed under the Clean Coal Technology Demonstration Program (CCTDP), the Power Plant Improvement Initiative (PPII), and the Clean Coal Power Initiative (CCPI). Program Update 2009 provides: (1) a discussion of the role of clean coal technology demonstrations in improving the nation’s energy security and reliability, while protecting the environment using the nation’s most abundant energy resource—coal; (2) a summary of the funding and costs of the demonstrations; and (3) an overview of the technologies being demonstrated, along with fact sheets for projects that are active, recently completed, or recently discontinued.

  2. Program Development and Evaluation - Education / Program Design

    OpenAIRE

    2004-01-01

    Susan Barkman: Evaluation Made Easy – Designing Instruments to Measure Program Impact. Cassandra S. Corridon: Meeting the Needs of Our Audience: Child Care Connections. Jerry Culen: Assessing Environmental Literacy in a 4-H Program. Ken Culp III: University of Kentucky Volunteer Administration Academy. Louise E. Davis: Mississippi’s Goal of Improving Quality Childcare in Unlicensed Settings. Theresa M. Ferrari: Hours of Opportunity or Hours of Risk. Martha S. Garton: Does a Week Long 4-H Cam...

  3. Choosing the Right Program

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Given the transient nature of the job market, fewer companies are willing to fund the better quality international or global programs, programs that can clearly add value for those focusing on a career in China. "The connection between the pricing point and the perceived value is missing, even when the same program, quality and degree are twice as much in the US. There is absolutely a disconnection between the local market and the high-end foreign or joint programs," says Ira Cohen, Rutgers International Executive MBA Program China director.

  4. FORTRAN and ASSEMBLER programs

    International Nuclear Information System (INIS)

    A collection of programs written in FORTRAN and ASSEMBLER programming languages used in DOS-IBM is presented. The problems solved are of different sorts: linear programming, integration, matrix calculus, computation of absorbed doses in teletherapy, data sets (files) on magnetic tapes and disks, completion of DOS operating system etc. For reasons of space no details are given on the numerical methods or supplements and devices developed in order to achieve superior programs as to computation time and accuracy of result, although these might have been of use. All the programs in the collection have been checked up on an IBM 370/135 computer. (author)

  5. C++ how to program

    CERN Document Server

    Deitel, Paul J

    2014-01-01

    This best-selling comprehensive text is aimed at readers with little or no programming experience. It teaches programming by presenting the concepts in the context of full working programs and takes an early-objects approach. The authors emphasize achieving program clarity through structured and object-oriented programming, software reuse and component-oriented software construction. The Ninth Edition encourages students to connect computers to the community, using the Internet to solve problems and make a difference in our world. All content has been carefully fine-tuned in response to a team of distinguished academic and industry reviewers.

  6. Programming in COBOL

    CERN Document Server

    Lancaster, G T

    2014-01-01

    Programming in COBOL is a simple yet concise how-to book that teaches the programming language in a short yet effective step-by-step manner, which can be easily understood by anyone with sufficient knowledge in information technology. Covering first the advantages of COBOL over other programming languages, the book discusses COBOL's divisions - identification, environment, procedure, and data, and then describes the testing of the COBOL source programs and program questions. The book is valuable for those who wish to learn basic COBOL language, but do not have the time to take manufacturers' o

  7. Beginning programming for dummies

    CERN Document Server

    Wang, Wallace

    2011-01-01

    Do you think the programmers who work at your office are magical wizards who hold special powers that manipulate your computer? Believe it or not, anyone can learn how to write programs, and it doesn't take a higher math and science education to start. Beginning Programming for Dummies shows you how computer programming works without all the technical details or hard programming language. It explores the common parts of every computer programming language and how to write for multiple platforms like Windows, Mac OS X, or Linux. This easily accessible guide provides you with the tools

  8. Foreign criteria and programs

    International Nuclear Information System (INIS)

    The concept of measurement quality assurance (MQA) as embodied in National Institute of Standards and Technology (NIST) programs is not generally used within European programs for testing or accreditation. Although the essential elements of quality control and quality assurance are in the European programs, the concept of testing the capability of the laboratory itself, in terms of its performance for the designated measurements, may not be included. Rather, the European programs use the concept of periodic calibration of laboratory reference standards against the next highest level of standards. Thus, they embody the concept of measurement traceability to appropriate primary standards. Within Europe a series of calibration accreditation programs has been established in the various countries tied together through a multilateral agreement. The radiation measurement programs are based on the International Organization for Standardization (ISO) 9000 series of standards. The purpose of this paper is to outline the overall operation of European Accreditation Programs in the radiation calibration and measurement areas. The operation of the radiation measurement programs of the National Measurement Accreditation Service (NAMAS) in the United Kingdom is described in detail along with other European programs. The manner in which these programs relate to individual dosimetry service programs is also described

  9. SSCL quality program overview

    International Nuclear Information System (INIS)

    The Quality Program for the Superconducing Super Collider Laboratory (SSCL) was developed for a number of reasons. The need for a quality program not only is a contractual requirement, but it also makes good economic sense to implement such a program. The quality program is the device used to coordinate the activities of different Laboratory organizations, such as Engineering and Procurement, and to improve operational reliability and safety. To be successful, the QA Program not only must satisfy Department of Energy (DOE) requirements and provide for flowdown of requirements to performing organizations, but must also be flexible enough so that the program is tailored to meet the needs of each internal organization. The keys to success are management support, acceptance by personnel, and cost effectiveness. These three items are assured by involving appropriate management at each step of program development, by personnel training and by feedback, and by programs to reduce defects and improve quality. Equally valuable is involvement of key organizations in program development. We will describe the basic SSCL Quality Program requirements, how the requirements are tailored to the needs of Laboratory organizations, and how the effectiveness of the program is validated

  10. Mini Project Programming Exams

    DEFF Research Database (Denmark)

    Nørmark, Kurt; Thomsen, Lone Leth; Torp, Kristian

    2008-01-01

    A number of different types of final programming exams used or considered at the Department of Computer Science, Aalborg University, are identified and analyzed. Based on this analysis, a new type of programming exam is introduced called a Mini Project Programming (MIP) exam. MIP is a group......-based programming assignment that is intended as a medium-scale programming effort followed by a final oral exam. MIP is characterized and compared to existing types of final programming exams by use of a number of independent criteria. The paper motivates the MIP approach and reports on our experience over four...... years. The MIP exam is a compromise between (1) a long problem-based project exam and (2) a short oral or written programming exam. It is concluded that the strengths of MIP are the high degree of realism in the exam assignment and comprehensiveness relative to the course syllabus. The main challenge...

  11. Interactive MESY-programs (IM-programs)

    International Nuclear Information System (INIS)

    MESY means MEchanical SYstems. The word is an abbreviation for a unique concept comprising the theoretical background, the philosophy and the related code of a programming system for the analysis of mechanical system. The term 'programming system' is used because the system consists of procedures the calls of which can be used to formulate the processes of problem solutions. The concept has been developed since 1966. Two special branches of it are the MESY-ROTRA and the DSS-MESY3 systems, which have now been widely utilized for ten years by and in partnership with KWU and NUCLEN. The core of the second system consists of FORTRAN routines from the MESY3 implementation. The IM-programs, interactive branches, which have been implemented since 1983, are prefabricated MESY3 programs to be used advantageously with workstations. In this context interactive means controlling the computation process from the screen while the process is going on: By answering questions with YES or NO or/and, by choosing control numbers from a menu or/and, by typing numbers or words and names of files as input data, by typing a question mark to display more explaining text, by typing an exclamation mark to accept user input e.g. as suggestions. The reason why the IM-programs are introduced here is not their interactive mode only, but also some characteristic attributes due to the concept. This paper is to make apparent its potential possibilities. (orig.)

  12. Inservice testing bases program

    International Nuclear Information System (INIS)

    Inservice testing (IST) programs generally address those components necessary for safe operation as specified in Subsections IWP-1100 and IWV-1100 of Section 11 (American Society of Mechanical Engineers Boiler and Pressure Vessel Code) and Position 11 of the US Nuclear Regulatory Commission Generic Letter 89-04. Program tables, generated manually or from computer databases, are frequently used to describe those components and testing requirements contained in IST programs. Table entries are usually derived from review of system drawings, accident analysis, and other technical documents; however, the bases for such entries are not always documented. Because IST programs are dynamic, the continual evaluation of program entries may be inhibited if bases for program entries are unclear. When IST programs have been developed by architect-engineers, nuclear steam supply system suppliers, or other contractors, the bases for IST program contents become even more nebulous to the program users. The presentation provides a discussion of IST bases programs used by Entergy Operations' four nuclear plants, and the benefits derived from their use

  13. Aspect-Oriented Programming

    Science.gov (United States)

    Elrad, Tzilla (Editor); Filman, Robert E. (Editor); Bader, Atef (Editor)

    2001-01-01

    Computer science has experienced an evolution in programming languages and systems from the crude assembly and machine codes of the earliest computers through concepts such as formula translation, procedural programming, structured programming, functional programming, logic programming, and programming with abstract data types. Each of these steps in programming technology has advanced our ability to achieve clear separation of concerns at the source code level. Currently, the dominant programming paradigm is object-oriented programming - the idea that one builds a software system by decomposing a problem into objects and then writing the code of those objects. Such objects abstract together behavior and data into a single conceptual and physical entity. Object-orientation is reflected in the entire spectrum of current software development methodologies and tools - we have OO methodologies, analysis and design tools, and OO programming languages. Writing complex applications such as graphical user interfaces, operating systems, and distributed applications while maintaining comprehensible source code has been made possible with OOP. Success at developing simpler systems leads to aspirations for greater complexity. Object orientation is a clever idea, but has certain limitations. We are now seeing that many requirements do not decompose neatly into behavior centered on a single locus. Object technology has difficulty localizing concerns invoking global constraints and pandemic behaviors, appropriately segregating concerns, and applying domain-specific knowledge. Post-object programming (POP) mechanisms that look to increase the expressiveness of the OO paradigm are a fertile arena for current research. Examples of POP technologies include domain-specific languages, generative programming, generic programming, constraint languages, reflection and metaprogramming, feature-oriented development, views/viewpoints, and asynchronous message brokering. (Czarneclu and

  14. Radioisotope Power Systems Program: A Program Overview

    Science.gov (United States)

    Hamley, John A.

    2016-01-01

    NASA's Radioisotope Power Systems (RPS) Program continues to plan, mature research in energy conversion, and partners with the Department of Energy (DOE) to make RPS ready and available to support the exploration of the solar system in environments where the use of conventional solar or chemical power generation is impractical or impossible to meet potential future mission needs. Recent programs responsibilities include providing investment recommendations to NASA stakeholders on emerging thermoelectric and Stirling energy conversion technologies and insight on NASA investments at DOE in readying a generator for the Mars 2020 mission. This presentation provides an overview of the RPS Program content and status and the approach used to maintain the readiness of RPS to support potential future NASA missions.

  15. Site Support Program Plan Infrastructure Program

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-09-26

    The Fiscal Year 1996 Infrastructure Program Site Support Program Plan addresses the mission objectives, workscope, work breakdown structures (WBS), management approach, and resource requirements for the Infrastructure Program. Attached to the plan are appendices that provide more detailed information associated with scope definition. The Hanford Site`s infrastructure has served the Site for nearly 50 years during defense materials production. Now with the challenges of the new environmental cleanup mission, Hanford`s infrastructure must meet current and future mission needs in a constrained budget environment, while complying with more stringent environmental, safety, and health regulations. The infrastructure requires upgrading, streamlining, and enhancement in order to successfully support the site mission of cleaning up the Site, research and development, and economic transition.

  16. Site Support Program Plan Infrastructure Program

    International Nuclear Information System (INIS)

    The Fiscal Year 1996 Infrastructure Program Site Support Program Plan addresses the mission objectives, workscope, work breakdown structures (WBS), management approach, and resource requirements for the Infrastructure Program. Attached to the plan are appendices that provide more detailed information associated with scope definition. The Hanford Site's infrastructure has served the Site for nearly 50 years during defense materials production. Now with the challenges of the new environmental cleanup mission, Hanford's infrastructure must meet current and future mission needs in a constrained budget environment, while complying with more stringent environmental, safety, and health regulations. The infrastructure requires upgrading, streamlining, and enhancement in order to successfully support the site mission of cleaning up the Site, research and development, and economic transition

  17. Programming Scala Scalability = Functional Programming + Objects

    CERN Document Server

    Wampler, Dean

    2009-01-01

    Learn how to be more productive with Scala, a new multi-paradigm language for the Java Virtual Machine (JVM) that integrates features of both object-oriented and functional programming. With this book, you'll discover why Scala is ideal for highly scalable, component-based applications that support concurrency and distribution. Programming Scala clearly explains the advantages of Scala as a JVM language. You'll learn how to leverage the wealth of Java class libraries to meet the practical needs of enterprise and Internet projects more easily. Packed with code examples, this book provides us

  18. Exobiology: The NASA program

    Science.gov (United States)

    Rummel, John D.; Harper, Lynn; Andersen, Dale

    1992-01-01

    The goal of NASA's Exobiology Program is to understand the origin, evolution, and distribution of life in the universe. To do this, the Exobiology Program seeks to provide a critical framework and some key research to allow NASA to bear the combined talents and capabilities of the agency and the scientific community, and the unique opportunities afforded by space exploration. To provide structure and direction to the quest for answers, the Exobiology Program has instituted a comprehensive research program divided into four elements which are being implemented at several of NASA's research centers and in the university community. These program elements correspond to the four major epochs in the evolution of living systems: (1) cosmic evolution of the biogenic compounds; (2) prebiotic evolution; (3) origin and early evolution of life; and (4) evolution of advanced life. The overall research program is designed to trace the pathways leading from the origin of the universe through the major epochs in the story of life.

  19. Test-driven programming

    Science.gov (United States)

    Georgiev, Bozhidar; Georgieva, Adriana

    2013-12-01

    In this paper, are presented some possibilities concerning the implementation of a test-driven development as a programming method. Here is offered a different point of view for creation of advanced programming techniques (build tests before programming source with all necessary software tools and modules respectively). Therefore, this nontraditional approach for easier programmer's work through building tests at first is preferable way of software development. This approach allows comparatively simple programming (applied with different object-oriented programming languages as for example JAVA, XML, PYTHON etc.). It is predictable way to develop software tools and to provide help about creating better software that is also easier to maintain. Test-driven programming is able to replace more complicated casual paradigms, used by many programmers.

  20. Programming in Biomolecular Computation:

    DEFF Research Database (Denmark)

    Hartmann, Lars; Jones, Neil; Simonsen, Jakob Grue;

    2011-01-01

    Our goal is to provide a top-down approach to biomolecular computation. In spite of widespread discussion about connections between biology and computation, one question seems notable by its absence: Where are the programs? We identify a number of common features in programming that seem...... conspicuously absent from the literature on biomolecular computing; to partially redress this absence, we introduce a model of computation that is evidently programmable, by programs reminiscent of low-level computer machine code; and at the same time biologically plausible: its functioning is defined...... by a single and relatively small set of chemical-like reaction rules. Further properties: the model is stored-program: programs are the same as data, so programs are not only executable, but are also compilable and interpretable. It is universal: all computable functions can be computed (in natural ways...

  1. Programming in Biomolecular Computation

    DEFF Research Database (Denmark)

    Hartmann, Lars; Jones, Neil; Simonsen, Jakob Grue

    2010-01-01

    Our goal is to provide a top-down approach to biomolecular computation. In spite of widespread discussion about connections between biology and computation, one question seems notable by its absence: Where are the programs? We introduce a model of computation that is evidently programmable......, by programs reminiscent of low-level computer machine code; and at the same time biologically plausible: its functioning is defined by a single and relatively small set of chemical-like reaction rules. Further properties: the model is stored-program: programs are the same as data, so programs are not only...... in a strong sense: a universal algorithm exists, that is able to execute any program, and is not asymptotically inefficient. A prototype model has been implemented (for now in silico on a conventional computer). This work opens new perspectives on just how computation may be specified at the biological level....

  2. Distributed programming using AGAPIA

    Directory of Open Access Journals (Sweden)

    Ciprian I. Paduraru

    2014-01-01

    Full Text Available As distributed applications became more commonplace and more sophisticated, new programming languages and models for distributed programming were created. The main scope of most of these languages was to simplify the process of development by a providing a higher expressivity. This paper presents another programming language for distributed computing named AGAPIA. Its main purpose is to provide an increased expressiveness while keeping the performance close to a core programming language. To demonstrate its capabilities the paper shows the implementations of some well-known patterns specific to distribute programming along with a comparison to the corresponding MPI implementation. A complete application is presented by combining a few patterns. By taking advantage of the transparent communication model and high level statements and patterns intended to simplify the development process, the implementation of distributed programs become modular, easier to write, in clear and closer to the original solution formulation.

  3. Parallel logic programming systems

    OpenAIRE

    Chassin De Kergommeaux, J.; Codognet, Philippe

    1992-01-01

    Parallelizing logic programming has attracted much interest in the research community, because of the intrinsic or and and parallelisms of logic programs. One research stream aims at transparent exploitation of parallelism in existing logic programming languages such as Prolog while the family of concurrent logic languages develops constructs allowing programmers to express the concurrency, that is the communication and synchronization between parallel process, inside their algorithms. This p...

  4. Computer Programming Job Analysis

    OpenAIRE

    Debdulal Dutta Roy

    2002-01-01

    This study investigated relative uses of computer programming job characteristics across different organizations and effects of different demographic variables on job analysis ratings. Data were collected from 201 computer programers of 6 different organizations through checklist. Principal component analysis noted four mostly used job characteristics as program writing and testing, human relations, data analysis and user satisfaction. Of them only data analysis differed among different organ...

  5. Explicit parallel programming

    OpenAIRE

    Gamble, James Graham

    1990-01-01

    While many parallel programming languages exist, they rarely address programming languages from the issue of communication (implying expressability, and readability). A new language called Explicit Parallel Programming (EPP), attempts to provide this quality by separating the responsibility for the execution of run time actions from the responsibility for deciding the order in which they occur. The ordering of a parallel algorithm is specified in the new EPP language; run ti...

  6. Smokeless Tobacco Reduction Program.

    OpenAIRE

    Glidden, L; Whigam, K

    1987-01-01

    To reduce the incidence and prevalence of oral cancer, the Smokeless Tobacco Reduction Program will consist of a mass media campaign, public oral screening, and a week-long school health program for 350 students in the seventh, eighth, and ninth grades in Willows, Glenn County, CA. Mass media will include radio, television, newspapers, posters, and literature. The program will use resources of the public health department and junior high school; it will also depend on 8 teachers and 25 peer l...

  7. Automatic Inductive Programming Tutorial

    OpenAIRE

    Aler, Ricardo

    2006-01-01

    Computers that can program themselves is an old dream of Artificial Intelligence, but only nowadays there is some progress of remark. In relation to Machine Learning, a computer program is the most powerful structure that can be learned, pushing the final goal well beyond neural networks or decision trees. There are currently many separate areas, working independently, related to automatic programming, both deductive and inductive. The first goal of this tutorial is to give to the attendants ...

  8. Child Care Subsidy Programs

    OpenAIRE

    David Blau

    2000-01-01

    Child care and early education subsidies are an important part of government efforts to increase economic independence and improve development of children in low-income families in the United States. This chapter describes the main subsidy programs in the U.S., discusses economic issues that arise in designing such programs and evaluating their effects, and surveys evidence on the effects of the programs. An important theme of the chapter is the tradeoff between the policy goals of increasing...

  9. A Radioisotope Inventory Program

    International Nuclear Information System (INIS)

    The Radioisotope Inventory Program maintains an accurate and up-to-date inventory of all radioisotopes used on campus. An instruction manual provides easy to use directions for using the program. The program is implemented on a Hewlett-Packard HP-85 microcomputer and can be used on other systems. The commands allow updating and changing licensee information easily and quickly. Data Security is maintained by placing the data on a removable tape cartridge and locking the cartridge

  10. The Greenfoot Programming Environment

    OpenAIRE

    Kölling, Michael

    2010-01-01

    Greenfoot is an educational integrated development environment aimed at learning and teaching programming. It is aimed at a target audience of students from about 14 years old upwards, and is also suitable for college- and university-level education. Greenfoot combines graphical, interactive output with programming in Java, a standard, text-based object-oriented programming language. This article first describes Greenfoot and then goes on to discuss design goals and motivations, strengths and...

  11. Programming as Metacalculation

    OpenAIRE

    Bantchev, Boyko

    2013-01-01

    Report published in the Proceedings of the National Conference on "Education in the Information Society", Plovdiv, May, 2013 Elements of an approach to teaching programming in school are described, based on the functional paradigm and harmonically blending programming, calculation, and algebra. We believe that it ensures a smooth introduction to programming, free of contrived concepts and constructs, and also fosters the teaching of a wider and deeper mathematics in school. Ass...

  12. Wetlands Reserve Program

    OpenAIRE

    US Government

    2007-01-01

    The Wetlands Reserve Program (WRP) is a voluntary program. It provides technical and financial assistance to eligible landowners to restore, enhance, and protect wetlands. Landowners have the option of enrolling eligible lands through permanent easements, 30-year easements, or restoration cost-share agreements. This program offers landowners an opportunity to establish, at minimal cost, long-term conservation and wildlife habitat enhancement practices and protection.

  13. Concept-Oriented Programming

    OpenAIRE

    Savinov, Alexandr

    2008-01-01

    Object-oriented programming (OOP) is aimed at describing the structure and behaviour of objects by hiding the mechanism of their representation and access in primitive references. In this article we describe an approach, called concept-oriented programming (COP), which focuses on modelling references assuming that they also possess application-specific structure and behaviour accounting for a great deal or even most of the overall program complexity. References in COP are completely legalized...

  14. Meteorological Monitoring Program

    International Nuclear Information System (INIS)

    The purpose of this technical report is to provide a comprehensive, detailed overview of the meteorological monitoring program at the Savannah River Site (SRS) near Aiken, South Carolina. The principle function of the program is to provide current, accurate meteorological data as input for calculating the transport and diffusion of any unplanned release of an atmospheric pollutant. The report is recommended for meteorologists, technicians, or any personnel who require an in-depth understanding of the meteorological monitoring program

  15. Los Alamos Programming Models

    Energy Technology Data Exchange (ETDEWEB)

    Bergen, Benjamin Karl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-07-07

    This is the PDF of a powerpoint presentation from a teleconference on Los Alamos programming models. It starts by listing their assumptions for the programming models and then details a hierarchical programming model at the System Level and Node Level. Then it details how to map this to their internal nomenclature. Finally, a list is given of what they are currently doing in this regard.

  16. Programming Language Pragmatics

    CERN Document Server

    Scott, Michael L

    2009-01-01

    Programming Language Pragmatics is the most comprehensive programming language textbook available today. Taking the perspective that language design and language implementation are tightly interconnected, and that neither can be fully understood in isolation, this critically acclaimed and bestselling book has been thoroughly updated to cover the most recent developments in programming language design. With a new chapter on run-time program management and expanded coverage of concurrency, this new edition provides both students and professionals alike with a solid understanding of the most impo

  17. An extended day program

    Directory of Open Access Journals (Sweden)

    Ševkušić-Mandić Slavica G.

    2002-01-01

    Full Text Available The paper presents the results of a pilot project evaluation, carried out as an action investigation whose aim was to provide a better quality extended day for primary school students. The project included the training of teachers involved in extended day program, designing of special activities performed by teachers with children once a week as well as changes and equipping of premises where children stay. The aims of the program were conception and performance of activities in a less formal way than during regular instructional days, linking of learning at school and acquired knowledge to everyday experiences, and work on contents contributing to the development of child's interests and creativity. The program was accomplished in a Belgrade primary school during the 2001/2002 academic year, comprising students of 1st and 2nd grades (N=77. The effects of the program were monitored throughout the academic year (observation and teachers' reports on accomplished workshops and at the end of the academic year (teachers and students' opinions of the program, academic achievement and creativity of students attending the extended day program compared with students not attending it. Findings about positive effects of the program on students' broadening of interests and willingness to express themselves creatively, indicate unequivocally that there is a need for developing special extended day programs. The extended day program is an opportunity for school to exert greater educational influence that has yet to be tapped.

  18. Parallel programming with PCN

    Energy Technology Data Exchange (ETDEWEB)

    Foster, I.; Tuecke, S.

    1993-01-01

    PCN is a system for developing and executing parallel programs. It comprises a high-level programming language, tools for developing and debugging programs in this language, and interfaces to Fortran and Cthat allow the reuse of existing code in multilingual parallel programs. Programs developed using PCN are portable across many different workstations, networks, and parallel computers. This document provides all the information required to develop parallel programs with the PCN programming system. It includes both tutorial and reference material. It also presents the basic concepts that underlie PCN, particularly where these are likely to be unfamiliar to the reader, and provides pointers to other documentation on the PCN language, programming techniques, and tools. PCN is in the public domain. The latest version of both the software and this manual can be obtained by anonymous ftp from Argonne National Laboratory in the directory pub/pcn at info.mcs. ani.gov (cf. Appendix A). This version of this document describes PCN version 2.0, a major revision of the PCN programming system. It supersedes earlier versions of this report.

  19. Construction program management

    CERN Document Server

    Delaney, Joseph

    2013-01-01

    Although construction is one of the largest industries in the United States, it lags behind other industries in its implementation of modern management techniques such as those contained in the Standard for Program Management (the Standard) by the Project Management Institute (PMI(R)). Construction Program Management details the successful use of the PMI(R) approach for the construction of capital programs. It demonstrates, through case studies, how implementation of PMI's set of tools and techniques can improve the chances of program success. Exploring tactical and strategic management method

  20. California's congestion management program

    International Nuclear Information System (INIS)

    One of the hottest topics in transportation planning today is California's Congestion Management Program (CMP). California's program has been suggested as a model to the rest of the United States for addressing transportation problems and for conforming to the federal Clean Air Act. This article introduces California's Congestion Management Program, describes some problems related to California's CMP legislation, outlines the major CMP elements, and briefly explains the issue of the environmental impact of CMPs. This information might assist others in developing their own CMP programs

  1. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Overview of Medicare Quality Programs Phases of Surgical Care Physician Quality Reporting ... Practice Management Practice Management Practice Management CPT Coding Bulletin Articles ...

  2. Practical C programming

    CERN Document Server

    Oualline, Steve

    1997-01-01

    There are lots of introductory C books, but this is the first one that has the no-nonsense, practical approach that has made Nutshell Handbooks® famous. C programming is more than just getting the syntax right. Style and debugging also play a tremendous part in creating programs that run well and are easy to maintain. This book teaches you not only the mechanics of programming, but also describes how to create programs that are easy to read, debug, and update. Practical rules are stressed. For example, there are fifteen precedence rules in C (&& comes before || comes before ?:). The practi

  3. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Payment Modifier Quality and Resource Use Reports Electronic Health Records (EHR) Incentive Program ... Practice Management Practice Management Practice Management CPT Coding Bulletin Articles ...

  4. Construction Experience Program (CONEX)

    International Nuclear Information System (INIS)

    A summary of the activities of the NEA WGRNR is introduced. In particular the following tasks related to the ConEx (Construction Experience Program) are presented: Rationale and goals of the ConEx program, Development of the event construction database ConEx and its structure, ConEx procedure for program management (uses of ConEx to create knowledge, conclusions of the ConEx synthesis first report on lessons learned during construction, Potential ConEx program uses for operating experience, training, etc.)

  5. Ostomy Home Skills Program

    Medline Plus

    Full Text Available ... Overview of Medicare Quality Programs Phases of Surgical Care Physician Quality Reporting System ... Practice Management Practice Management Practice Management CPT Coding Bulletin Articles ...

  6. Veterinary Services Program

    Data.gov (United States)

    Federal Laboratory Consortium — Mission: To provide quality veterinary medical care and environmental enrichment programs for all animals, representing nine different species. To provide guidance...

  7. Thermal-Radiation Program

    Science.gov (United States)

    Anderson, Gordon

    1993-01-01

    Thermal Radiation Analyzer System (TRASYS) computer program is software program having generalized capability to solve equations of radiation-related aspects of thermal-analysis problems. Computes total thermal-radiation environment for spacecraft in orbit. Software calculates internode-radiation-interchange data as well as data on rates of incidence and absorption of heat originating from environmental radiant sources. Provides data of both types in format directly usable by such thermal-analyzer programs as SINDA '85/FLUINT (available from COSMIC, program number MSC-21528). CRAY version of TRASYS (P25) written in FORTRAN 77. Other versions available upon request.

  8. Distributed computing support program`s databases

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, Amy [Saint Cloud State Univ., MN (United States)

    1996-05-01

    The Distributed Computing Support Program (DCSP) is the current system for keeping track of computer hardware maintenance throughout the Lawrence Livermore National Laboratory. DCSP consists of four separate Ingres databases each with their own support files. The process of updating and revising the support files, to make the business process more efficient is described in this paper.

  9. Program Performance Inventory: Six Juvenile Offender Programs.

    Science.gov (United States)

    Thomalla, Terri Groff; Dougherty, Victoria J.

    This report describes the performance of 6 Connecticut juvenile justice alternative sanction programs in 14 qualitative areas: community reintegration; outcomes and evaluation; assessment methods; risk factors; escalation of criminal activity; family involvement; community involvement; work ethic and vocational training; education and life skills;…

  10. A Silent Safety Program

    Science.gov (United States)

    Goodin, James Ronald

    2006-01-01

    NASA's Columbia Accident Investigation Board (CAIB) referred 8 times to the NASA "Silent Safety Program." This term, "Silent Safety Program" was not an original observation but first appeared in the Rogers Commission's Investigation of the Challenger Mishap. The CAIB on page 183 of its report in the paragraph titled 'Encouraging Minority Opinion,' stated "The Naval Reactor Program encourages minority opinions and "bad news." Leaders continually emphasize that when no minority opinions are present, the responsibility for a thorough and critical examination falls to management. . . Board interviews revealed that it is difficult for minority and dissenting opinions to percolate up through the agency's hierarchy. . ." The first question and perhaps the only question is - what is a silent safety program? Well, a silent safety program may be the same as the dog that didn't bark in Sherlock Holmes' "Adventure of the Silver Blaze" because system safety should behave as a devil's advocate for the program barking on every occasion to insure a critical review inclusion. This paper evaluates the NASA safety program and provides suggestions to prevent the recurrence of the silent safety program alluded to in the Challenger Mishap Investigation. Specifically targeted in the CAM report, "The checks and balances the safety system was meant to provide were not working." A silent system safety program is not unique to NASA but could emerge in any and every organization. Principles developed by Irving Janis in his book, Groupthink, listed criteria used to evaluate an organization's cultural attributes that allows a silent safety program to evolve. If evidence validates Jams's criteria, then Jams's recommendations for preventing groupthink can also be used to improve a critical evaluation and thus prevent the development of a silent safety program.

  11. Building Technologies Program Multi-Year Program Plan Program Overview 2008

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2008-01-01

    Building Technologies Program Multi-Year Program Plan Program Overview 2008, including market overview and federal role, program vision, mission, design and structure, and goals and multi-year targets.

  12. Bruce NGS rehabilitation program

    International Nuclear Information System (INIS)

    The paper summarizes the status at the time of writing of the program to rehabilitate the 4-unit Bruce A Nuclear Generating Station. The aim of the program was to restore the target 85% capacity factor by repair and proactive maintenance

  13. Programs as Data Objects

    DEFF Research Database (Denmark)

    This book constitutes the refereed proceedings of the Second Symposium on Programs as Data Objects, PADO 2001, held in Aarhus, Denmark, in May 2001. The 14 revised full papers presented were carefully reviewed and selected from 30 submissions. Various aspects of looking at programs as data objects...

  14. Learning Apex programming

    CERN Document Server

    Kaufman, Matt

    2015-01-01

    If you are a developer who has some object-oriented programming experience, Learning Apex Programming is the perfect book for you. This book is most appropriate for developers who wish to gain an understanding of the Force.com platform and how to use Apex to create business applications.

  15. Marketing University Outreach Programs.

    Science.gov (United States)

    Foster, Ralph S., Jr., Ed.; And Others

    A collection of 12 essays and model program descriptions addresses issues in the marketing of university extension, outreach, and distance education programs. They include: (1) "Marketing and University Outreach: Parallel Processes" (William I. Sauser, Jr. and others); (2) "Segmenting and Targeting the Organizational Market" (Vaughan C. Judd); (3)…

  16. Air Pollution Training Programs.

    Science.gov (United States)

    Public Health Service (DHEW), Rockville, MD.

    This catalog lists the universities, both supported and not supported by the Division of Air Pollution, which offer graduate programs in the field of air pollution. The catalog briefly describes the programs and their entrance requirements, the requirements, qualifications and terms of special fellowships offered by the Division of Air Pollution.…

  17. Marketing a laser program.

    Science.gov (United States)

    Pfister, J I

    1992-04-01

    The objective of a marketing program is to enhance knowledge and perceived desirability of a laser service, thereby improving profitability. Among the 15 tools that make up an effective marketing program are researching the market, identifying an appropriate niche, developing a marketing plan, using publications and advertising, and generating public relations. PMID:1301873

  18. Secure Dynamic Program Repartitioning

    DEFF Research Database (Denmark)

    Hansen, Rene Rydhoff; Probst, Christian

    2005-01-01

    Secure program partitioning has been introduced as a language-based technique to allow the distribution of data and computation across mutualy untrusted hosts, while at the same time guaranteeing the protection of confidential data. Programs that have been annotated with security types are...

  19. Child Nutrition Program

    Institute of Scientific and Technical Information of China (English)

    潘志强

    2005-01-01

    The Child Nutrition Program invites all students to participate in the school breakfast and lunch program at school. Our goal is to improve the health and education of students by providing nutritious meals that promote food choices for a healthy diet. Failure to eat balanced meals increases the risk of illness including obesity ,

  20. INEL BNCT Program

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, A.L. (ed.)

    1991-08-01

    This Bulletin presents a summary of accomplishments and highlights in the Idaho National Engineering Laboratory's (INEL) Boron Neutron Capture Therapy (BNCT) Program for August 1991. This bulletin includes information on the brain tumor and melanoma research programs, Power Burst Facility (PBF) technical support and modifications, PBF operations, and updates to the animal data charts.