Carbon Fiber Plate Research Articles

Dispersion curve estimation via phased array beamforming methods

Localization of scattering sources via active ultrasonic inspection in plate-like structures requires knowledge of the structure’s dispersion relation and material properties. Often the dispersion relation and material properties are unknown, uncertain, or difficult to model due to material complexity and variability in material properties, geometry, and/or environment, thereby requiring in situ estimation. Two methods are presented for estimating guided wave dispersion curves (phase and group velocity) in a multimodal, multipath environment using a phased array. Phase and group velocities are estimated in situ on an aluminum and carbon fiber plate and compared to theoretical values. Scattering from plate boundaries is localized using the estimated phase and group velocity curves through beamforming and ranging via time of flight.

A force sensor with five degrees of freedom using optical intensity modulation for usage in a magnetic resonance field

In this paper, a precise small 5-DOF (degree of freedom) force sensor is proposed for use in a strong EMF (electromagnetic field) environment. Detecting modules using CFPs (carbon fiber plates) and transducing modules using the optical modulation principle are adopted in order not to be affected by the EMF. For miniaturization of the multi-DOF force sensor, a 2-DOF transducing module using a spherical mirror and a 3-DOF transducing module using a plane mirror were designed and integrated. The design parameters of highly sensitive transducing modules were investigated and determined experimentally. To combine with these transducing modules, a 2-DOF detecting module using CFP single leaf springs and a 3-DOF detecting module using a CFP tripod spring were also designed. Considering the easy calibration process and convenient design change, the elastic detecting modules were designed so that they deform independently according to each input force component. A calibration test confirmed that the detecting modules deform linearly and independently of the input force. The results of the evaluation tests showed that the range and resolution of forces were ±4 N and 0.94–7.1 mN and the range and resolution of moments were ±120 N mm and 0.023–0.034 N mm, respectively. The high sensitivity and the linearity of the measuring results were also verified.

Composite-Antenna-Structure for Broadband Frequency

We study a composite-antenna-structure (CAS) having high electrical and mechanical performances that we have designed and fabricated. The CAS, consisting of a glass/epoxy face sheet and a honeycomb core, acts as a basic mechanical structure, in which a spiral antenna type is embedded. To increase the intensity, a carbon fiber plate is used as a bottom sheet. This structure of the 0.5 ~ 2 GHz band has a gain of 5 ~ 9 dBi with circular polarization characteristics and reflection loss below -10 dB within the desired frequency band.

Guided viscoelastic wave in circumferential direction of orthotropic cylindrical curved plates

In this paper, guided circumferential wave propagating in an orthotropic viscoelastic cylindrical curved plate subjected to traction-free conditions is investigated in the frame of the Kelvin-Voight viscoelastic theory. The obtained three wave equations are decoupled into two groups, Lamb-like wave and SH wave. They are separately solved by the Legendre polynomial series approach. The availability of the method is confirmed through the comparison with the published data of the SH wave for a viscoelastic flat plate. The dispersion curves and attenuation curves for the carbon fiber and prepreg cylindrical plates are illustrated and the viscous effect on dispersion curves is shown. The influences of the ratio of radius to thickness are analyzed.

다자유도 탄소섬유판 힘/토크 센서 개발

A force/torque sensor using carbon fiber plate was designed and developed to make the sensor be able to measure a wide range of multi degree of force and torque. Using carbon fiber plate of 0.3 mm thickness, the sensor was designed and developed, which has a μN level order of resolution and about 0.01 N ~ 390 N of wide measurement range. The elastic deformation part has a tripod plate structure and strain gauges are attached on the part to detect the force/torque. The coefficient of determination for the sensor is over 0.955 by the calibration experiment so that the linearity of the sensor is confirmed to be good. Also, experiments on applying 0.005 ~ 40 ㎏ (0.05 ~ 390 N) to each axis were implemented and the sensor is proved to be safe under a high load. Finally, to verify the function calculating the direction of load vector, the directions of various load vectors which have the same magnitude but different directions and the directions of the calculated load vectors are compared and analyzed to accord well.

Terahertz thermal wave nondestructive test

This work aims at developing a new excitation method for thermal wave nondestructive test(NDT)-Terahertz excitation. In the paper we introduce a theoretical model of heat conduction for periodical THz excitation. BWO (backward wave oscillator) terahertz source is employed to heat a carbon fiber plate with wave absorbing coating, surface temperature variations and distributions are captured by an infrared camera, and Canny edge algorithm is used to process thermal images to show the defects. Result of flash pulse thermography serves as comparison, and the advantages of THz thermal wave NDT are discussed. The combination of THz technology and infrared thermal wave NDT is realized.

Design and fabrication of a composite-antenna-structure for broadband frequency with microwave absorber

Here we design, fabricate, and study a composite-antenna-structure (CAS) with excellent electrical and mechanical properties. The CAS, consisting of a glass/epoxy face sheet and a honeycomb core, acts as a basic mechanical structure in which a spiral type antenna is embedded. To increase the signal intensity, a carbon fiber plate is used as the bottom sheet. This reflector interrupts radiation, causing the wave from the antenna source to flow to the end of the arms without sufficient radiation. To overcome this problem, a microwave absorber is used for unwanted radiation to reduce the effect of the reflector. We measured the antenna performance by the return loss, axial ratio, gain, and radiation pattern. The structure showed a bandwidth of 0.5–2 GHz and a gain of 5–9 dBi, with circular polarization characteristics and a reflection loss below −10 dB within the desired frequency band.

Research on Debonding Formula Model of RC Beams Strengthened with CFRP Sheets

Debonding of concrete occurs when the interface principal stress reaches the ultimate tensile strength. We propose the use of carbon fiber plate attached to the beam bottom, which makes finite element analysis of the mechanical properties of debonding concrete beams more reasonable. In addition, formulas of this theory are given and applied in the finite element analysis. Finally, it is shown by a number of experimental results.

The Principle and Calculation Method of Carbon Fiber Reinforcement for Tunnels and Underground Structures

There will emerge cracks or damage due to the action of rock pressure or its own shortcomings and low strength for the lining structure in tunnel or underground engineering, especially at the places of excessive bending moment and tensile stress because of bias pressure where concrete will be pull apart for the deficiency of strength even to cause leakage and durability insufficient. Conventional maintenance and reinforce methods are time-consuming and laborious, and the effect is also not ideal. It is simple, timesaving and having a significant and lasting effect to use carbon fiber reinforcement method. This paper studied structure’s failure mechanism and on the basis of that the principle of fiber-plate reinforcement from the angle of structural plastic development, then studied the improvement of structure’s mechanical character and the change of design calculation method for single section of underground structure with carbon fiber plates by using the research method of plane-strain. At the same time, the typical model of integral failure for single section was analyzed and the calculation method and formulae of bearing capacity and reinforcing steel bars were deduced, which remedied the shortfall in the design specification for concrete structure. In the end, by comparing the calculation results of structure with fiber plates and that with not fiber plates based on engineering example, the conclusion that structure’s bearing capacity and capability of resistance to deformation had obvious improvement was obtained.

External bonded shear reinforcement for T‐section beams

AbstractStrengthening reinforced concrete (RC) beams in shear using carbon fibre‐reinforced polymer (CFRP) has been found to enhance, significantly, the shear capacity of existing RC beams. In previous studies the use of steel plates bonded externally to the RC beams was found to improve the shear performance of these beams. Most of the previous work was conducted on RC beams having rectangular sections. The main objective of this paper is to gain a better understanding and enhance the experimental database of shear behaviour of RC T‐beams strengthened with externally bonded reinforcement (EBR) systems. The present study encompasses some of the important parameters such as direction of EBR fibre alignment and the strengthening materials made of carbon‐fibre sheets, steel plates or steel bars for shear strengthening. The contribution of EBR to the shear capacity of the T‐beams was computed using three design codes and compared with the experimental output. A series of RC T‐beams was tested experimentally with the CFRP and steel strips carefully aligned and spaced. A reference T‐beam and a rectangular beam were tested as well to explore the effect of the internal shear reinforcement and the existence of the flange on the shear capacity of the beam.

Load Test on Reinforced Concrete Beams Strengthened by Carbon Fiber Laminated Plates - A Case Study

A load test was performed on reinforced concrete beams that were strengthened with carbon fibers. Seventy five thousands blocks were placed in four stages. A quality and management team worked continuously in the testing process. No creep effects were noticed with the use of carbon fiber plates, an interesting observation.

Shear tests of carbon fiber plates bonded to concrete with control of snap-back

In the present paper the problem of brittle debonding between carbon-fiber plates (FRP) and concrete was studied by means of single lap shear tests. Driving the test by controlling the displacement of the free edge of the plate made it possible to describe the pull-out curve up to complete debonding, including the snap-back branch. This permitted to observe that, in the present tests, failure mode and brittleness strongly depend upon the bond length. In particular, specimens with long bond length display a snap-back in the pull-out curve, whereas specimens with short bond length display a softening. Besides, debonding occurs with a transition from mode II to a mixed mode fracture as the bond length decreases, showing different failure mechanisms and a remarkable reduction of the dissipated fracture energy. Moreover, the measured bond-slip relationships show a reduction of the bond strength close to the free edge of the plate that is caused by peeling stresses. Finally, results of the experimental tests are compared with finite element simulations with standard bond-slip laws.

Experimental Study on Strengthened Bridge Structures with Carbon Fiber Plate

In order to analyze the impact of anchor length, ends anchorage measures, strength of concrete, shear-span ratio, reinforcement ratio and the amount of carbon fiber plate on the bearing capacity of strengthened bridge structures with carbon fiber plate, 11 pieces of rectangle beams are fabricated for flexural experimental study. The experimental results show that the ultimate bearing capacity of the specimens increase different degree as different strengthened schemes: the bearing capacity of rectangle beams with plate end anchorage has increased remarkably; The beams have greater bearing capacity with more anchorage length in contrast to those without any anchorage measure; The ultimate bearing capacity enhanced more prominent for those specimens with low shear-span ratio and low reinforcement ratio.

SU-E-T-541: A Clinical Approach to Account for the Attenuation of Varian Exact IGRT Couch Top for Spine Stereotatic Radiosurgery Patients

Purpose: The purpose of this work is to develop an approach to account for the attenuation of Varian Exact IGRT couch top for spine cancer patients in spine stereotatic radiosurgery. Methods: Varian Exact IGRT couch which has carbon fiber plates sandwiched with a plastic foam core was used for this study. Transmission of 6MV x‐rays through the couch was measured at various oblique beam angles. Based on the measured values, we modeled the couch top as a stored organ in Pinnacle treatment planning system (TPS) for spine stereotatic radiosurgery (SSRS) patients. A planner can load the virtual couch top and override the density when designing a treatment plan to account for the couch attenuation explicitly. The dosimetric impact of the couch top on DVHs was investigated in 3 representative patients. Results: At normal incidence, percentage of the attenuation of the Exact IGRT couch for a 6MV beam was measured to be 2.40% and 2.68% for field size of and , respectively. The attenuation was found to be gantry angle dependent, with maximum attenuation 3.90% at 120° for field size of and 4.25% at 130° for , respectively. By using a fixed density of 1.05 within the thin carbon fiber layers, the calculated attenuation for the virtual couch top were 2.38% and 2.94% for field, 4.15%, and 4.57% for field, respectively, which agreed well with the measurement. Without considering the couch attenuation, the average loss of target coverage was 7.1% in three representative cases we analyzed. Conclusions: The attenuation of Varian Exact IGRT Couch Top should not be ignored when using the couch top for SSRS patients. A clinical approach was developed to account for the attenuation. A calibrated virtual couch model can be used to account for the attenuation in the treatment planning process.

Influence of footwear typically worn during field hockey participation, velocity and surfaces on tibial accelerations during locomotion

INTRODUCTION Field Hockey is a popular sport played predominantly on artificial sports surfaces requiring sustained periods of locomotion at various velocities. During human locomotion the body is exposed musculoskeletal transient shocks that have been linked to various injuries (Aguinaldo and Mahar 2003). The magnitude of the impact shocks have been reported as being affected by the velocity of locomotion, movement strategies, the surface and the footwear worn (Clarke et al 1983). Therefore choosing appropriate conditions should reduce the levels of impact shock experienced reducing the risk of injury. PURPOSE OF THE STUDY The Purpose of this study was to investigate the influence of footwear, surface and speed on the magnitude of tibial shock. METHODS Nine male participants, (Age 21 + 1.69, Height 175.75 + 6.56 and Mass 78.13 + 12.11) volunteered to take part in this study. All participants were injury free at the time of data collection and completed an informed consent form. A tri-axial accelerometer (Biometrics ACL300) sampling at 1000Hz was mounted to a lightweight carbon-fibre plate via a securely glued lightweight bolt and thread. The accelerometer signal was recorded by a Biometrics DataLog system (Biometrics Ltd, Gwent, UK). The accelerometer signal was filtered at 60Hz using a Butterworth 4th order zero-lag low-pass filter. The concrete surface at the side of the pitch was typical of the sort of surface on which field hockey participants would warm up prior to matches. Participants were required to run in each of the footwear at 5m.s-1 (running) and 3.3m.s-1 (jogging). RESULTS Significant differences were observed between running and jogging for the different surfaces. Significant differences in the tibial axial peak were also reported when comparing the effects of surface during running, however during jogging significant differences were not found. Significant differences between mean tibial acceleration values in the Saucony Running, Umbro Soccer Astroturf, and Gryphon Venom, when compared to Umbro Soccer Moulded during running on synthetic surfaces. No other significant differences were found across the population of participants between the shoes for the 3 other surface and velocity conditions (running on synthetic surface, jogging on concrete, running on concrete). DISCUSSION It appears that footwear only has a measureable effect across the population of participants, during running at a higher speed (5m.s-1). The significant differences recorded were all cases where the Umbro Moulded shoes exposed the athlete to higher tibial axial accelerations than the other shoe conditions. This occurred only in the running group on the synthetic sports surface This may have been replicated on the concrete but it was considered not safe for participants to run in Umbro Moulded shoes on a concrete surface. Furthermore, the same footwear (Umbro Moulded) as in the previous chapter was highlighted as exposing the population to a significant increase in detrimental kinetic factors. The results of this research suggest that participating in high velocity activities on hard concrete surfaces, exposes the musculoskeletal to significantly larger impact shocks. This information can be used by coaches to select suitable activities with the surfaces available to them. This investigation also identified that during running on synthetic sports surfaces, moulded soccer shoes with hard deep cleats expose the body to larger impact shocks than shoes designed for running and synthetic sports surfaces. Therefore these types of shoes should not be used in field hockey participation on such surfaces. Significant differences in the magnitude of tibial shock between similar footwear designs used by field hockey participants were also identified using the methodologies in this study. The evidence from individual participant provides some assistance for footwear selection. However, the findings of this study demonstrated that shoes can reduce impact shock for one individual while increasing it for another. Therefore, for a participant to be confident of making the correct choice of footwear in relation to exposure to tibial shock, the footwear needs to be tested on an individual basis.

Evaluation of two‐dimensional bolus effect of immobilization/support devices on skin doses: A radiochromic EBT film dosimetry study in phantom

In this study, the authors have quantified the two-dimensional (2D) perspective of skin dose increase using EBT film dosimetry in phantom in the presence of patient immobilization devices during conventional and IMRT treatments. For 6 MV conventional photon field, the authors evaluated and quantified the 2D bolus effect on skin doses for six different common patient immobilization/support devices, including carbon fiber grid with Mylar sheet, Orfit carbon fiber base plate, balsa wood board, Styrofoam, perforated AquaPlast sheet, and alpha-cradle. For 6 and 15 MV IMRT fields, a stack of two film layers positioned above a solid phantom was exposed at the air interface or in the presence of a patient alpha-cradle. All the films were scanned and the pixel values were converted to doses based on an established calibration curve. The authors determined the 2D skin dose distributions, isodose curves, and cross-sectional profiles at the surface layers with or without the immobilization/support device. The authors also generated and compared the dose area histograms (DAHs) and dose area products from the 2D skin dose distributions. In contrast with 20% relative dose [(RD) dose relative to dmax on central axis] at 0.0153 cm in the film layer for 6 MV 10 x 10 cm2 open field, the average RDs at the same depth in the film layer were 71%, 69%, 55%, and 57% for Orfit, balsa wood, Styrofoam, and alpha-cradle, respectively. At the same depth, the RDs were 54% under a strut and 26% between neighboring struts of a carbon fiber grid with Mylar sheet, and between 34% and 56% for stretched perforated AquaPlast sheet. In the presence of the alpha-cradle for the 6 MV (15 MV) IMRT fields, the hot spot doses at the effective measurement depths of 0.0153 and 0.0459 cm were 140% and 150%, (83% and 89%), respectively, of the isocenter dose. The enhancement factor was defined as the ratio of a given DAH parameter (minimum dose received in a given area) with and without the support device. For 6 MV conventional 10 x 10 cm2 field, the enhancement factor was the highest (3.4) for the Orfit carbon fiber plate. As for the IMRT field, the enhancement factors varied with the size of the area of interest and were as high as 3.8 (4.3) at the hot spot of 5 cm2 area in the top film layer (0.0153 cm) for 6 MV (15 MV) beams. Significant 2D bolus effect on skin dose in the presence of patient support and immobilization devices was confirmed and quantified with EBT film dosimetry. Furthermore, the EBT film has potential application for in vivo monitoring of the 2D skin dose distributions during patient treatments.

Experimental study on the reinforcement of secondary flexural members with prestressed carbon fiber plates

Experimental study on the reinforcement of secondary flexural members with prestressed carbon fiber plates

Development of a yield monitoring system for citrus mechanical harvesting machines

A load cell based yield monitoring system was developed for the Oxbo citrus mechanical harvesting machines. The yield monitoring system consisted of a GPS receiver, a mass flow sensor and data processing and storage units. The mass flow sensor consisted of four load cells attached to a carbon-fiber plate which sensed the impact force created by the oranges hitting the plate. A mathematical model was developed to relate the impact force to fruit mass. Laboratory tests were conducted on a test rig that replicated the flow of oranges to measure the accuracy of the system under a controlled environment. The system performed very well under laboratory conditions (R 2 = 0.99 and an average error of 3.3%). In addition, a field test was conducted in a citrus orchard in Florida to evaluate the performance of the system under field conditions. Of the 72 rows used in the field test, the first 10 rows were used to calibrate the computed weight. A correlation of R 2 = 0.97 between the actual weight and the computed weight was found from the field data with an average error of 7.81%.

지속하중을 받는 탄소섬유판의 장기 거동

본 연구에서는 외부프리스트레스 탄소섬유판에 의한 보강기술에서 긴장력을 포함하는 지속하중이 작용하였을 때의 장기거동을 평가하기 위한 실험연구를 수행하였다. 지속하중 도입을 위한 실험계획은 탄소섬유판에 직접 인장력을 도입하는 직접 지속하중 방식과 휨 실험체를 통한 휨 지속하중으로 구분하여 실시하였다. 직접 지속하중에 의한 실험은 탄소섬유판의 종류별로 약 700일에 걸쳐 실시하여 탄소섬유판의 장기 크리프/릴렉세이션 등의 변형을 주로 평가하였으며, 휨 지속하중 실험에서는 탄소섬유판의 정착시 정착장치에서의 슬립량을 주로 평가하기 위해 약 90일 간으로 수행되었다. 일방향 탄소섬유판에 대한 2년간의 지속하중 실험 결과에 의하면, 탄소섬유판의 크리프나 릴렉세이션과 같은 재료자체의 변형 및 정착장치에서의 슬립에 기인한 응력손실은 적은 것으로 나타났다. 그러나, 강판매입형 탄소섬유판은 강판의 항복변형률을 초과하여 도입된 긴장력으로 인하여 재료 자체의 변형에 의한 자체 응력손실이 발생되었으므로 이에 대한 보완이 필요한 것으로 판단된다. 아울러, 탄소섬유판의 정착과정에 발생되는 긴장력의 즉시 손실량은 응력도입 초기의 약 10% 정도이므로 프리스트레스의 도입시에는 이를 고려하여 긴장력을 결정할 필요성이 있을 것으로 판단된다.

RC beam strengthened with pre-stressed CFP under the secondary load

Abstract Feasibility of using pre-stressed carbon fiber plates to strengthen reinforced concrete beams was studied. Based on the characteristics of carbon fiber plates, we developed a pre-stress clamp and a device for applying the pre-stress. Contrast tests were conducted between ordinary carbon fiber plates and a pre-stressed carbon fiber plate and between secondary loaded carbon fiber plates and a concrete beam strengthened with a secondary loaded carbon fiber plate. On this basis, we analyzed the failure pattern, the width of cracks and their distribution, the cracking load, the yield load, the limit load and the relation between load and deflection. The results indicate that using pre-stressed carbon fiber plates to strengthen concrete beams is feasible and effective.