• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.5
• /
• pp.839-854
• /
• 2018

This study was performed to evaluate the performance of GFRP plate reinforced segments for TBM tunnel support. Recently, the SFRC segment has been applied to prevent local damage such as reduction of the amount of reinforcing bars of the segment, crack control and breakage. However, the steel fiber used in the SFRC segment has a problem of durability deterioration due to fiber corrosion. Compared with the RC segment, the maximum flexural load reduction of the SFRC segment hinders the broad application range of the TBM tunnel segment. Therefore, GFRP plate was considered as a stiffener for the maximum load increase of SFRC segment, and structural synthetic fiber without corrosive concern was used as a substitute for steel fiber. The flexural performance of the segment was evaluated by using the type of reinforcing fiber and GFRP plate thickness as the main parameters. As a result, the maximum load and the flexural toughness were increased by 21.78~23.03% and 0.5~7.96%, respectively, as compared with the segments reinforced with reinforcing fiber and GFRP plate of 3 mm thickness.

• Journal of the Korean Geosynthetics Society
• /
• v.4 no.1
• /
• pp.27-36
• /
• 2005

Discharge capacity of the fiber mat and the fiber drain made with natural fibers abstracted from plant source was evaluated by permeability test for fiber mat and Delft type test and composite discharge capacity test using disturbed clayey soils for fiber drain. The permeability test results for environmentally friendly coconut fiber mat prove that fiber mat has outstanding permeability in substituting permeable sand. However, discharge capacity of fiber drain evaluated by conventional Delft type discharge capacity test was relatively lower than that of plastic drain board. Nevertheless, settlement and pore pressure dissipation behaviors of fiber drain and plastic drain board installed clay soil during the composite discharge capacity test were almost similar to that of plastic drain board. It is found that the natural fiber drain satisfies requiring minimum discharge capacity in substituting the conventional plastic drain board.

• Composites Research
• /
• v.22 no.6
• /
• pp.23-31
• /
• 2009

This paper investigated acoustic emission (AE) characteristics in association with various fracture processes of glass fiber reinforced plastic skin/ aluminum honeycomb core (GF-AH) hybrid composites under compressive and bending loads. Various failure modes such as skin layer fracture, skin/core interfacial fracture, and local plastic yield buckling and cell wall adhesive fracture occurring in the honeycomb cell wall were classified through the fracture identification in association with the AE frequency and amplitude analysis. The distribution of the event-rate in which it has a high amplitude showed a procedure of cell wall adhesive fracture, skin/core interfacial debonding and fiber breakage, whereas distribution of different peak frequencies indicated the plastic deformation of aluminum cell wall and the friction between honeycomb walls. Consequently, the fracture behaviors of GF-AH hybrid composites could be characterized through a nondestructive evaluation employing the AE technique.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.31 no.1
• /
• pp.53-61
• /
• 2011

Edge notched A16061-T6 aluminum was repaired with a GFRP composite patch as a function of the number of stacking, Damage progress of specimen for tension load has been monitored by acoustic emission(AE), AE energy rate, hit rate, amplitude, waveform and 1st peak frequency distribution were analyzed. Fracture processes were classified into Al cracking, Fiber breakage, Resin cracking and Delamination. Displacement of a specimen can be divided into Region I, II and ill according to acoustic emission characteristics. Region II where the patch itself was actually fractured was focused on to clarify the AE characteristics difference for the number of stacking.

• Composites Research
• /
• v.31 no.6
• /
• pp.332-339
• /
• 2018

Fiber metal hybrid laminate (FML) can be used as an economic material with superior mechanical properties and light weight than conventional metal by bonding of metal and FRP. However, there are disadvantages that it is difficult to predict fracture behavior because of the large difference in properties depending on the type of fiber and lamination conditions. In this paper, we study the failure behavior of hybrid materials with laminated glass fiber reinforced plastics (GFRP, GEP118, woven type) in Al6061-T6 alloy. The Al alloys were coated with GFRP 1, 3, and 5 layers, and fracture behavior was analyzed by using a static test and a low cycle fatigue test. In the low cycle fatigue test, strain - life analysis and the total strain energy density method were used to analyze and predict the fatigue life. The Al alloy did not have tensile properties strengthening effect due to the GFRP coating. The fatigue hysteresis geometry followed the behavior of the Al alloy, the base material, regardless of the GFRP coating and number of coatings. As a result of the low cycle fatigue test, the fatigue strength was increased by the coating of GFRP, but it did not increase proportionally with the number of GFRP layers.

• Composites Research
• /
• v.27 no.3
• /
• pp.83-89
• /
• 2014

The purpose of this study is to improve the strength and thermal conductivity of polybutylene terephthalate (PBT) by embedding various additives. Specimens were prepared using PBT pellets embedded with glass fibers (GF) and boron nitride (BN) powders. The test results showed that tensile strength decreased, and thermal conductivity increased with increasing BN contents. with thermal shock cycles conducted, unfilled PBT showed a considerable decrease in failure strain and strength, whereas strength and thermal conductivity of glass fiber and BN particle-embedded PBT had little differeces. With increasing BN, the thermal conductivity of PBT composites was highly improved.

• Applied Chemistry for Engineering
• /
• v.34 no.5
• /
• pp.515-521
• /
• 2023

In this study, waste carbon fiber obtained by pyrolysis of carbon fiber reinforced plastic (CFRP) was used to produce carbon fluoride through vapor phase fluorination and recycled as a reducing electrode material for lithium primary batteries. First, the physicochemical properties of the waste carbon fiber obtained by pyrolysis were determined, and the structural and chemical properties of carbon fluoride were analyzed to evaluate the effect of vapor phase fluorination on the waste carbon fiber. XRD analysis confirmed that the hexagonal network carbon laminated structure (002 peak) of the waste carbon fiber was gradually converted into a carbon fluoride structure (CF_X, 001 peak) as the temperature of gas phase fluorination increased. The discharge capacity of the lithium primary battery produced using this carbon fluoride was up to 862 mAh/g. This was compared to the discharge capacity of carbon fluoride-based Li-ion batteries made of other carbon materials. These results suggest that carbon fluoride made from waste CFRP-based carbon fibers can be used as a reducing electrode material for Li-ion batteries.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.21 no.6
• /
• pp.920-925
• /
• 2012

A study of vehicle weight lightening has been progressed to reduce the fuel consumption. In this paper, the body floor in an EV (Electric Vehicle) bus has been applied by composites as CFRP and GFRP. In order to analyse a various reliability and safety, an experiment and FEM analysis was carried out to obtain weight lightening. Especially, the joint. An effective design is obtained through an experiment as well as FEM analysis. Results of stress analysis of GFRP material showed twice as much displacement than those of CFRP material. Among three kinds of joint methods, the bond joint method is occurred to a substantial shape change in the body and floor. It is found that the rivet joints are fairly suitable for stress sustaining capability.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.3
• /
• pp.262-268
• /
• 2014

This research introduces the structural design and the validation results of the flexible high speed coupling for 2MW class wind turbine which transmit and cut off torque between gear box and generator. The high speed coupling requires electrical insulation to prevent electrical surface damages on gear box. Therefore glass fiber reinforced plastics is applied to absorb the vibration and deformation of power train and to transmit required torque. Finite element analysis was performed to optimize the thickness and accumulation number of glass fiber reinforced plastics. Torque limiter which cut off the abnormal torque is designed in frictional disc type. The design of the coupling was validated with the performance test of prototype.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.5
• /
• pp.869-886
• /
• 2018

Rockbolt is one of the most common supports used to reinforce discontinuous rock during underground excavation. Extra drain pipes are installed to improve excavation workability and the anchorage of rockbolts in water bearing ground. The drain pipe is effective in improving the workability by providing drainage path, but it is difficult to expect the reinforcement effect, increasing disturbance of the discontinuous rock mass and the construction cost. To solve this problem, dual purpose rockbolt (DPR) has been developed for the reinforcement of rock and the drainage of ground water. DPR was able to improve the mechanical and hydraulic stability of the rocks quickly and economically. Two kinds of DPRs using FRP (Fiber Reinforced Plastic) and steel were investigated for the mechanical and hydraulic performance. Also, the workability and stability of DPR were analyzed.