Research on Radiation Characteristics of Polymeric Plastic Fiber

The anti-radiation mechanism of polymeric plastic fiber is analyzed. The radiation characteristic of this type fiber is studied. Our experimental results indicate that under the low radiation dosage (below 1 kGy) the plastic optical fiber’s transmission rate rises instead of descends while this type of fiber is radiated by γ ray, electron beam and proton beam respectively. After a period of time, it gradually reaches a constant value. But under the high radiation dosage (above 1 kGy) the fiber’s transmission rate descends after radiation. Later, it gradually goes up to a constant value.

Monte-Carlo simulation to determine detector efficiency of plastic scintillating fiber

Fundamental characteristics of the plastic scintillating fiber (PSF) as a detector for electromagnetic radiation (X & γ) are obtained by GEANT4 detector simulation tool package. The detector response to radiation with energy of 10~400 keV is found out. Energy deposition as well as detector efficiency (DE) of the PSF are studied. In order to make linear array of the PSF for imaging purpose, the optimum length of fiber is also estimated.

Performance of a plastic scintillation fiber dosimeter based on different photoelectric devices

The photoelectric device of a scintillation dosimeter converts photons produced by radiation into an electrical signal.Its features directly determine the overall performance of the dosimeter.For a plastic scintillation fiber dosimeter(PSFD)with a current readout mode,systematic studies of the stability and light-dose response were performed for the photomultiplier tube(PMT),silicon photomultiplier(SiPM),avalanche photodiode(APD),and photodiode(PD).The temperature stability,long-term stability,repeatability,signal-to-noise ratio(SNR),and current dose response of the PSFD with the abovementioned photoelectric devices were studied using a pulsed LED light source and the Small Animal Radiation Therapy platform.An exponential relationship between the dark/ne current and temperature was obtained for all the devices.I is shown that the APD is the most sensitive device to temperature,with a current dependence on temperature reaching 6.5%C^(-1)at room temperature,whereas for the other devices this dependence is always<0:6%C^(-1).In terms of long-term stability,the net current of PD can change by up to 4%when working continuously for 8 h and 2%when working intermittently for 32 h,whereas for the other devices,the changes are all<1%.For the dose response,the PMT and SiPM exhibit excellent linear responses and SNRs within the range of 0.1-60 Gy/min For the PSFD with a current readout mode,the performance of the PMT and SiPM is concluded to be better than that of the other devices in the study.In particular,the SiPM,which has a compact size,low bias voltage,and antimagnetic interference,has great advantages for further applications.

Quasi-plane-hypothesis of strain coordination for RC beams seismically strengthened with externally-bonded or near-surface mounted fiber reinforced plastic

The application of fiber reinforced plastic（FRP）,including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement（EBR） and near-surface mounted（NSM） strengthening techniques.This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods,including externally-bonded and near-surface mounted FRP,to study the strain coordination of the FRP and steel rebar of the RC beam.Since there is relative slipping between the RC beam and the FRP,the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis;that is,the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height（h 0） of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of the FRP and steel rebar satisfies the equation：ε FRP =βε steel,and the value of β is equal to 1.1-1.3 according to the test results.

Study on plant fiber/plastic composites as the substrate of floorboard

三种 composites (纤维 / 聚丙烯， fiber/Polyethelene， andfiber/Polystyrene ) 被为地板的底层使用热紧迫的过程做，每种 composites 的性质被测试。分别地，没有联合代理人，有联合增加的代理人的 PP/wood 纤维， PS/fiber，和 PE/fibercomposites 的粗腐殖质被 18.4% ， 37.1% ，和 42% 与那些相比提起。在三种纤维 / 塑料 composites 之中， fiber/PP 合成最好的机械性能，和它能满足合格等级产品的优秀标准并且当联合代理人被增加时，达到中国的优秀等级产品。表演用 PE/fiber 或 PS/fiber 做的合成能仅仅与联合超过合格产品等级增加的代理人。

Development and Properties of Glass Fiber Reinforced Plastics Geogrid

Glass fiber reinforced plastics geogrid has a wide application in the field of soil reinforcement because of its high strength, good toughness, and resistance to environmental stress, creep resistance and strong stability. In order to get high-powered glass fiber reinforced plastics geogrid and its mechanical characteristics, the properties and physical mechanical index of geogrid have been got through the study of its raw material, production process and important quality index. The analysis and study have been made to the geogrid＇s mechanical properties with loading speed, three-axial compression, temperature tensile test and FLAC3D numerical simulation, thus obtain the mechanical parameters of its displacement time curve, breaking strength and elongation at break. Some conclusions can be drawn as follows： （a） Using glass fiber materials, knurling and coated projection process, the f^acture strength and corrosion resistance of geogrid are greatly improved and the interlocking bite capability of soil is enhanced. （b） The fracture strength of geogrid is related to temperature and loading rate. When the surrounding rock pressure is fixed, the strength and anti-deformation ability of reinforced soil are significantly enhanced with increasing reinforced layers. （c） The pullout test shows the positive correlation between geogrid displacement and action time. （d） As a new reinforced material, the glass fiber reinforced plastics geogrid is not mature enough in theoretical research and practical experience, so it has become an urgent problem both in theoretical study and practical innovation.

Entrance and Exit Defects During Coarse Pitch Orbital Drilling of Carbon Fiber Reinforced Plastic Plates

Formation of entrance and exit defects in coarse pitch orbital drilling(CPOD)of carbon fiber reinforced plastic(CFRP)plates was investigated.Deep observation on entrance and exit morphology shows tear and burr are typical defects.Meanwhile,tear is more obvious than burr,and more entrance tears emerge than exit tears.As one of the major causes of entrance and exit defects in CPOD,cutting forces were substaintially studied by contrast experiments.Then,the effect of cutting parameters on entrance and exit tear was qualitatively analyzed through a single factor test.Experiment results indicate that the variation of rotation speed has little influence on entrance and exit tear.Increasing tangential feed per tooth can enlarge entrance tear,but bring little effect on exit tear.By increasing axial feed pitch,the hole entrance and exit show severe tear.When revolution radius grows bigger and bigger,entrance and exit tear firstly decreases,and then increases.Finally,the models of tear and delamination during CPOD of CFRP were established,the formation mechanisms of entrance and exit defects were revealed,and the control strategies were accordingly put forward.

Determination of spatial resolution of plastic scintillation fiber array with a simple method

The spatial resolution of a position sensitive gamma-ray detector configuration based on plastic scintillation fiber array was measured using a Monte Carlo simulation method. Both point spread function and modulation transfer function (MTF) were presented. The factors that influence the spatial resolution were also discussed. The results of the simulation showed that the intrinsic spatial resolution was consistent with the size of the physical pixels and a few centimeters spatial resolution could be obtained under certain circumstances.

Feasibility study of wave-motion milling of carbon fiber reinforced plastic holes

Carbon fiber reinforced plastic(CFRP)has been applied in aeronautics,aerospace,automotive and medical industries due to its superior mechanical properties.However,due to its difficult-to-cut characteristic,various damages in twist drilling and chip removal clog in core drilling could happen,inevitably reducing hole quality and hole-manufacturing efficiency.This paper proposes the wave-motion milling(WMM)method for CFRP hole-manufacturing to improve hole quality.This paper presents a motion path model based on the kinematics of the WMM method.The wave-motion cutting mode in WMM was analyzed first.Then,comparison experiments on WMM and conventional helical milling(CHM)of CFRP were carried out under dry conditions.The results showed that the hole surface quality of the CFRP significantly improved with a decrease of 18.1%–36%of Ra value in WMM compared to CHM.WMM exerted a significantly weaker thrust force than that of CHM with a reduction of 12.0%–24.9%and 3%–7.7%for different axial feed per tooth and tangential feed per tooth,respectively.Meanwhile,the hole exit damages significantly decreased in WMM.The average tear length at the hole exit in WMM was reduced by 3.5%–29.5%and 35.5%–44.7%at different axial feed per tooth and tangential feed per tooth,respectively.Moreover,WMM significantly alleviated tool wear.The experimental results suggest that WMM is an effective and promising strategy for CFRP hole-manufacturing.

Strain coordination of quasi-plane-hypothesis for reinforced concrete beam strengthened by epoxy-bonded glass fiber reinforced plastic plate

The testing of thirteen reinforced concrete （RC） beams strengthened by epoxy-bonded glass fiber reinforced plastic plate （GFRP） shows that the RC beam and the GFRP plate with epoxy bonding on it can work fairly well in coordination to each other. But there is relative slipping between RC beam and GFRP plate. And the strain of GFRP and steel rebar of RC beam satisfies the quasi-plane-hypothesis, that is, the strain of longitudinal fiber that parallels to the neutral axis of plated beam within the scope of effective height （h0） of the cross section is in direct proportion to the distance from the fiber to the neutral axis. The strain of GFRP and steel rebar satisfies the equation: ε GFRP =Kε steel .

Thermal Structure of Glass Fiber Reinforce Plastic Support Structure

The assembled form of thick-wall glass fiber reinforced plastics (GFRP) tube and 0Cr18Ni9 austenitic stainless steel pipes was designed as the radius thermal-insulating and load-supporting structure in cryogenic vessels. In order to study the thermal leakage and gap changes on the support structure, as well as radius temperature and stress distribution on GFRP tube, an experimental investigation has been taken. The results indicate that the support structure is proved to fit well as thermal-insulating and load-supporting part in cryo-genic vessels, furthermore has high security during cryogenic applications.

BUCKLING AND POSTBUCKLING ANALYSIS OF ELASTO-PLASTIC FIBER METAL LAMINATES

The elasto-plastic buckling and postbuckling of fiber metal laminates （FML） are studied in this research. Considering the geometric nonlinearity of the structure and the elasto- plastic deformation of the metal layers, the incremental Von Karman geometric relation of the FML with initial deflection is established. Moreover, an incremental elasto-plastic constitutive relation adopting the mixed hardening rule is introduced to depict the stress-strain relationship of the metal layers. Subsequently, the incremental nonlinear governing equations of the FML subjected to in-plane compressive loads are derived, and the whole problem is solved by the iterative method according to the finite difference method. In numerical examples, the effects of the initial deflection, the loading state, and the geometric parameters on the elasto-plastic buckling and postbuckling of FML are investigated, respectively.

Square concrete columns strengthened with carbon fiber reinforced plastics sheets at low temperatures

Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceability of damaged concrete columns at low temperatures. The failure of the specimens,in most cases,takes place within the middle half of the columns. And the failure of strengthened columns is sudden and explosive. The CFRP sheets increase both the axial load capacity and the ultimate concrete compressive strain of the columns. The ultimate loads of strengthened columns at-10,0 and 10 ℃ increase averagely by 9.09%,6.63% and 17.83%,respectively,as compared with those of the control specimens. The axial compressive strength of strengthened columns is related to the curing temperatures. The improvement of axial compressive strength decreases with reducing temperature,and when the temperature drops to a certain value,the improvement increases with falling temperature.

Double linear strain distribution assumption of RC beam strengthened with external-bonded or near-surface mounted fiber reinforced plastic

Rehabilitation of existing structures with fiber reinforced plastic(FRP)has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high specific stiffness.The strain coordination results of 34 reinforced concrete beams(four groups)strengthened with different methods were presented including external-bonded or near-surface mounted glass or carbon FRP or helical rib bar in order to study the strain coordination of the strengthening materials and steel rebar of RC beam.Because there is relative slipping between concrete and strengthening materials(SM),the strain of SM and steel rebar of RC beam satisfies the double linear strain distribution assumption,that is,the strain of longitudinal fiber parallel to the neutral axis of plated beam within the scope of effective height(h0)of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of SM and steel rebar satisfies the equation εGCH=βεsteel,where the value of β is equal to 1.1-1.3 according to the test results.

Behaviour of Multiscale Progressive Damage for Different Matrix Glass Fiber Reinforced Plastics Bars

The damage formation and evolution of glass fiber reinforced plastics( GFRP) bar on mechanical properties were mainly evaluated by theoretical analysis and numerical calculations which lack of test basis of damage process. The two different matrices of unsaturated polyester and vinylester GFRP bars were selected to carry out a series of macro-mesoscopic physical and mechanical tests to analyze the tensile progressive damage process on a multiscale. The formation of apparent crack,the bonding of internal components as well as the strain change were all reflected damage evolution of GFRP bar,and a certain correlation existed between them. Wherein the matrix has an obvious impact on the damage of bar,the component stress transfer effect of vinylester bar is better than unsaturated polyester from crack propagation observation and scanning electron microscopy( SEM). The cyclic loading tests quantitatively reflect the difference of damage accumulation between different matrix bars,and the failure load of bars decreases nearly 10%.

Experimental study on ductility improvement of reinforced concrete rectangular Columns retrofitted with a new fiber reinforced plastics method

Reinforced concrete （RC） columns lacking adequately detailed transverse reinforcement do not possess the necessary ductility to dissipate seismic energy during a major earthquake without severe strength degradation. In this paper, a new retrofit method, which utilized fiber-reinforced plastics （FRP） confinement mechanism and anchorage of embedded bars, was developed aiming to retrofit non-ductile large RC rectangular columns to prevent the damage of the plastic hinges. Carbon FRP （CFRP） sheets and glass FRP （GFRP） bars were used in this test, and five scaled RC columns were tested to examine the function of this new method for improving the ductility of columns. Responses of columns were examined before and after being retrofitted. Test results indicate that this new composite method can be very effective to improve the anti-seismic behavior of non-ductile RC columns compared with normal CFRP sheets retrofitted column.

Two-dimensional X-ray imaging using plastic scintillating fiber array

Due to its low cost, flexibility and convenience for long distance data transfer, plastic scintillation fiber (PSF) have been increasingly used in building detectors or sensors for detecting various radiations and imaging. In this work, the performance of using PSF coupled with charge-coupled devices (CCD) to build area detectors for 2D X-ray imaging is studied. We describe the experimental setup and show the obtained images from CCD. Modulation Transfer Function (MTF) of the PSF array is also presented and compared to earlier reports.

Microstructure of Carbon Fiber and Carbon Reinforced Plastic

This study is the investigation of the microstructure of different types of carbon fiber. They were compared with the carbonized and graphitized fibers. Results of structural researches have been presented. It was found that the damage varies from different pollution and the damage of the monofibers. The effect of the pollution of the monofiber was determined.

Some characteristics of X-ray imaging for energy region of over 100 keV using plastic scintillation fiber array

In this work, characteristics of using PSFs (plastic scintillation fibers) coupled with CCD (charge-coupled devices ) to build area detectors for high energy X-ray imaging are studied with a Monte Carlo simulation, which cover an energy range of a few hundred keV to about 20 MeV. It was found that the efficiency of PSF in detecting X-ray with energy above a few hundred keV is low. We can use large incident flux to increase the output signal to noise ratio (SNR). The performance can also be improved by coating PSF with X-ray absorption layers and the MTF of the system is presented. By optimizing the absorption layer thickness, the crosstalk of the area detector built with PSF decreases.

Efficiency of employing fiber-based finite-length plastic hinges in simulating the cyclic and seismic behavior of steel hollow columns compared with other common modelling approaches

The accuracy and effi ciency of the modelling techniques utilized to model the nonlinear behavior of structural components is a signifi cant issue in earthquake engineering. In this study, the suffi ciency of three diff erent modelling techniques that can be employed to simulate the structural behavior of columns is investigated. A fi ber-based fi nite length plastic hinge (FB-FLPH) model is calibrated in this study. In order to calibrate the FB-FLPH model, a novel database of the cyclic behavior of hollow steel columns under simultaneous axial and lateral loading cycles with varying amplitudes is used. By employing the FB-FLPH model calibrated in this study, the interaction of the axial force and the bending moment in columns is directly taken into account, and the deterioration in the cyclic behavior of these members is implicitly considered. The superiority of the calibrated FB-FLPH modelling approach is examined compared with the cases in which conventional fi ber-based distributed plasticity and concentrated plasticity models are utilized. The effi ciency of the enumerated modelling techniques is probed when they are implemented to model the columns of a typical special moment frame in order to prove the advantage of the FB-FLPH modelling approach.