FRP Composite Material Research Articles

EFEKTIVITAS ANGKUR EPOKSI TERHADAP KEKANGAN EKSTERNAL BALOK BETON BERTULANG DENGAN PERKUATAN CFRP

Externally Bonded Carbon Fiber Reinforced Polymer (EB-CFRP) with U-wrap is one of the alternative external strengthening of modern reinforced concrete beams, which has been proven effective in significantly increasing flexural and deformation capacities. Although quite effective in increasing the structural capacity, external reinforcement needs to be studied further about its failure behavior, the avoided failure is called debonding, an interface bond failure between the FRP composite material and the concrete material. Epoxy has a fairly high material resistance, but its use as a reinforcing composite bonding material needs further investigation. Adding epoxy anchors at the ends of CFRP can mobilize the tensile strength in CFRP, eliminating or delaying debonding failure. Epoxy anchors (epoxy-filled grooves) are expected to be effective and flexible for application to various forms of components of reinforced concrete structures that have been reinforced with EB-CFRP. Currently, there are no standards and guidelines for applying FRP anchors. However, research has been conducted on the failure pattern of FRP anchors with U-style wrapping which can avoid debonding so that failure with FRP rupture can be achieved. This study examines the effectiveness of epoxy anchorage in improving the external strengthening of reinforced concrete beams with EB-CFRP reinforcement. The behavior of epoxy anchors in reinforced concrete beams with EB-CFRP will be investigated through experimental tests.

Design and Analysis of FRP Composite Drive Shaft for Light Motor Vehicle

To make light vehicles such as cars fuel-efficient, which in turn cars make economical, the vehicle should have a lighter weight. The composite materials are lightweight with extra strength as well as stiffness; the replacement of FRP composite materials to conventional metal (SM45C) materials applied in automotive car components can cut back the weight and enhance the mechanical properties of those components. This task deals with the power shaft of MARUTI OMNI to design the shaft for its minimal dimensions and fulfil modern-day disadvantages with specification then replace traditional metallic material with Carbon/Epoxy FRP composite material. Then a component version created for individual dimensions in CATIA V5R19 software. As soon as modeling, Torsional buckling evaluation and Modal analysis could be carried out for propeller shafts the use of ANSYS R14.5 to validate the theoretical calculations and analytical outcomes. The received outcomes are compared and Carbon/Epoxy Fiber Reinforced Polymer composite material is selected as a better alternative material for normal steel material in terms of many mechanical properties for light motor cars.

Cyclic Behavior of FRP Strengthened Beam-Column Joints under Various Concrete Damage Levels

This paper is intended to examine the efficiency of utilizing the FRP composite material with an externally bonded technique in enhancing the behavior of the damaged B-C joints and controlling their failure mode using the NLFEA approach. At first, the modeled Beam-Column joint was validated as per the previously-attained experimentally-attained results. Later, the model was widened to experiment with the impact of axial-column load and the concrete compressive strength on the reinforced and un-reinforced models with FRP. To run the experiment, there were three cases of applying the axial column load: no load applied (0%), applying 25%, applying 50%, and applying 75%, while the concrete compressive strength degradation level was (0% damage), (25% damage), and (50% damage). All models were evaluated for structural performance, considering: the failure mode, stresses distribution, and the ultimate capacities in pulling and pushing with its corresponding displacements. However, the horizontal load-displacement hysteretic loops and envelopes, stiffness degradation, displacement ductility, and energy dissipation were reported. The experimental results revealed that using FRP to externally-reinforce B-C joints improved overall cyclic performance, as the FRP caused a rise in the ultimate load capacity, horizontal displacement, ductility of displacement, and displacement energy dissipation, while it slowed down the stiffness degradation. In addition, the FRP material converted the failure mode of the region between the joint and column from brittle to ductile due to the formation of a plastic hinge only on the side of the beam when the axial column load exceeded 25%. It must be noticed that when the column’s axial load is less than 25%, the ultimate capacity of axial load and resultant deflection is solely improved. However, it has been stated that increasing the column’s axial loading by 25% increases the resulting stiffness degradation by 3% for undamaged joints, which further increases by 16% for each increased damage level. In contrast, the absorbed energy is increased by 170% under axial loading, increasing by 25%, which is reduced to only one-fourth under the various damage levels. Generally, the resulting observations help specialized engineers retrofit appropriate B-C joints in already-standing buildings due to their accuracy.

Study on the Effect of Salt Solution on Durability of Basalt-Fiber-Reinforced Polymer Joints in High-Temperature Environment.

Due to the low price and good comprehensive properties, FRP composite material has become a new type of civil application material in recent years. In this paper, Araldite® 2012 adhesive was used to bond basalt-fiber-reinforced polymer (BFRP), and the durability of its bonded joints was investigated. Experiments were carried out at 80 °C/DI water (deionized water), 80 °C/3.5% NaCl solution (3.5% SS), and 80 °C/5.0% NaCl solution (5.0% SS) at 0- (unaged), 10-, 20-, and 30-day aging. The specimen and BFRP in the environment of 80 °C/DI water, 80 °C/3.5% SS, and 80 °C/5.0% SS found salt solution under the condition of all sample water absorption decreases, and the activity of salt solution chemistry was weaker compared with deionized water. The load–displacement curve of the joint failure was obtained through quasi-static tensile experiments, and it was found that the adhesive would undergo a post-curing reaction that had a positive impact on the stiffness of the joint in a high-temperature environment. At the same time, it was found that the joint failure strength decreased less in the salt solution environment, and deionized water was more destructive than the salt solution. Referring to the change in water absorption, it was found that the change in the mechanical properties of the joint was mainly related to the permeation effect of the polymer. The change in the Tg of adhesive was measured by differential scanning calorimetry (DSC). It was found that Tg would decrease after aging, and the change in Tg was mainly related to the mobility of the molecular chain. Thermogravimetric analysis (TGA) was used to analyze the thermal behavior of the epoxy resin and some organic matter, and the main weight loss stage was 340–450 °C, which was the complete degradation of epoxy resin and some organic matter. Macro visual and microscopic scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to analyze the failure section, and it can be concluded that the failure mode of joint tear failure transitioned to cohesion in the late–mixed interface failure, at the visible interface between the fiber and the resin matrix.

Design, pultrusion manufacturing, characterization, and reliability testing of a novel PMMA-based glass FRP composite material

Thermosetting resins have a limited ability to absorb impacting energy and deform in the transversal direction. Thermoplastics, on the other hand, are reformable meaning their shape can be modified after the polymerization process has occurred. However, they are generally more viscous, making them non-ideal candidates in impregnation-based pultrusion manufacturing. This paper presents the experimental design, manufacturing, microstructural characteristics, and mechano-environmental testing results of pultruded Ø9.3 mm poly-methyl methacrylate (PMMA) thermoplastic GFRP rebars. The mechanical and environmental testing, performed via heat/UV/water exposure, cold environment, and corrosion followed by a series of 3-point flexural bending tests, revealed no statistical difference in the means of the flexural strengths between the thermoset- and thermoplastic-based GFRPs.

Effect of drilling process parameters on delamination factor in drilling of pultruded glass fiber reinforced polymer composite

Drilling of FRP composite materials finds widespread applications in many engineering fields but the Fiber breakage, delamination, spalling, pull-out, fuzzing are some of the difficulties This distinguishes FRP composite material drilling from ordinary material drilling. In the current work, The Pultruded glass fiber reinforced polymer composite (PGFRP) with hybrid filler produced at optimum pultrusion process parameters. Drilling characteristics such as drill bit lip angle, spindle speed, and feed rate have all been studied in view of delamination factor in the PGFRP composites with hybrid filler. Taguchi's single response optimization approach was used to find the best drilling parameters. It was found That optimum drilling parameter for optimal delamination factor in the PGFRP composite of given composition are spindle speed 3000 rpm, feed rate 200 mm/min and 1000 lip angle of twist drill.

Research on the aging characteristics for different FRP composite material before and after 5000h multi-factor aging

In order to reveal the the aging characteristics for different FRP composite material before and after 5000h multi-factor aging, different resin-based/glass fiber composites are prepared, and the effects of various factors such as mechanical strength, microscopic interface and thermal stability on the aging resistance of composites are discussed. The results shows that the flexural strength retention rates of the composite samples are above 90% after 5000h multi-factor aging, and the aging resistance is good and meets the project requirements, SEM scanning displays that there is no obvious cracks on the interface between the glass fibers and the resin matrix after multi-factor aging test, and the interface is not affected obviously by various aging factors, the modified polyurethane PU and modified polyurethane PUR composite materials also show good aging resistance.

Artificial Neural Network Applied to Prediction of Buckling Behavior of the Thin Walled Box

Composite materials are mostly used in applications where stiffness-to-weight or strength-to-weight ratios are critical. For example, there can be produced a large number of acceptable designs that support a specific loading condition by varying fibre orientation in each ply, or in a certain number of plies. Due to ease of construction, structural elements, such as box structures, are widely used as a load bearing member in the fields of civil, mechanical and aeronautical engineering. The paper presents an analysis of finite element stability of a thin-walled structure which can be used in civil constructions. The structure is made of FRP composite material. The structure is stiffened with ribs which are made of the same composite, steel and aluminum. The critical buckling pressure was determined for this structure. The advantage of using FRP and sandwich composite, compared to conventional materials as steel or aluminum, consists in high strength to weight ratios, high corrosion resistance, lightweight and excellent fatigue performance. A neural network model was created and used for the prediction of stability behavior of the analyzed elements.

Experimental analysis of Delamination, Thrust Force and Surface roughness on Drilling of Glass Fibre Reinforced Polymer Composites Material Using Different Drills

This work mainly focus on the drilling of GFRP composite material. Drilling of FRP composite material is different than the other material due to its anisotropic behaviour. During drilling of FRP composites some serious damage are occur such as; fiber pull-out, metric cracking and delamination. Drilling induced delamination is the major problem during mechanical drilling. Thrust force plays important role in drilling of FRP composite material. In this experiment, three different types of drills; helical flute (HSS) drill, Carbide tipped straight shank (K20) drill and Solid carbide 8 facet drills has been used. Tool materials are consider as major factor, which is responsible for drilling induced damage. Cutting parameters also influence drilling induced damage. Drilling induced delamination has been measured by using image processed technique. The results indicate that qualities of drill holes significantly improved when solid a carbide 8 facet drill was used.

Numerical simulation of squat reinforced concrete wall strengthened by FRP composite material

The advanced design rules and the latest known earthquakes, have imposed a strengthening of reinforced concrete structures. Many research works and practical achievements of the application of the external reinforcement by using FRP composite materials have been particularly developed in the recent years. This type of strengthening seems promising for the seismic reinforcement of buildings. Among of the components of structures that could affect the stability of the structure in case of an earthquake is the reinforced concrete walls, which require in many cases a strengthening, especially in case where the diagonal cracks can be developed. The intent of this paper is to present a numerical simulation of squat reinforced concrete wall strengthened by FRP composite material (carbon fiber epoxy). The intent of this study is to perform finite element model to investigate the effects of such reinforcement in the squat reinforced concrete walls. Taking advantage of a commercial finite element package ABAQUS code, three-dimensional numerical simulations were performed, addressing the parameters associated with the squat reinforced concrete walls. An elasto-plastic damage model material is used for concrete, for steel, an elastic-plastic behavior is adopted, and the FRP composite is considered unidirectional and orthotropic. The obtained results in terms of displacements, stresses, damage illustrate clearly the importance of this strengthening strategy.

Prediction of Load Capacity Variation in FRP Bonded Concrete Specimens Using Brownian Motion

In wet lay-up process, dry fiber sheets are saturated with a polymer and applied to the concrete surface by hand. This causes relatively large variation in properties of the cured FRP composite material. It is hard to know the exact mechanical properties of the FRP constructed by wet lay-up process. In addition, the stiffness of FRP changes during debonding process due to different amount of concrete attached to the debonded FRP at different locations. It is also inevitable to have considerable variations in the strength of concrete. Therefore, the behaviour of FRP bonded concrete members varies among specimens even when the same materials are used. The variation of localized FRP stiffness and concrete strength can be combined in a single parameter as variation of the localized interfacial fracture energy. In an effort to effectively model the effects of the variation of interfacial fracture energy on the load versus deflection responses of FRP bonded concrete specimens subjected to Mode I and Mode II loading, a random white noise using a one-dimensional standard Brownian motion is added to the governing equations, yielding stochastic differential equations. By solving these stochastic equations, the bounds of load carrying capacity variation with 95% probability are found for different experimental tests.

Design and installation of floating type photovoltaic energy generation system using FRP members

In this paper, we present the result of investigations pertaining to the development of floating type photovoltaic energy generation system. For the floating structure, durable and light-weight materials such as a pultruded FRP composite material are essential. Pultruded FRP has superior mechanical properties and excellent corrosion–resistance compared with those of conventional structural materials. In the paper, we discussed the development concepts of the floating type photovoltaic energy generation system briefly. The mechanical properties of the FRP structural member used in the structural system are investigated through the tensile and shear tests. Test results are used in the finite element analysis and design of the system. Link system which is composed of pultruded FRP, used tire, and PE rope is also analyzed by the finite element method. Finally, floating type photovoltaic energy generation system is designed, fabricated, and installed successfully at the sea site in Korea. In addition, the energy production of floating PV energy generation system is measured and compared with that of land type plant. Energy productions of floating type from June to August are significantly higher, but the energy productions from September to October are lower.

Current Situation and Prospect of the Application of FRP in Material Engineering

The FRP composite material can replace the traditional under certain conditions, the wood structure of steel and reinforced materials, with high strength, light weight, resistance to corrosion and fatigue resistance, temperature stability and good special, because by civil engineeringcircles. This paper introduces the characteristics of FRP composites, the application of FRP composites in civil engineering are discussed, finally, the prospect of FRP materials are introduced.

FRP 복합재료 방향타 장착 근해어선의 해상시운전시험 결과분석

This paper reports the results of a comparative study on rudder performance between the steel rudders that have been used in coastal angling fishing boats in the 20-GT class and the newly developed FRP composite material rudders. In order to compare the rudder performances of these two types, a sea trial test was carried out to investigate the speed performance, fuel consumption, and ship's turning ability. The results showed that the sea trial performance of the FRP composite rudder was better than that of the steel rudder type in terms of the sea speed, fuel consumption rate, and turning ability.

Advanced T-ray nondestructive evaluation of defects in FRP solid composites

Nondestructive testing technique using T-ray (terahertz ray) receives attention these days as a new field of test engineering. In this study, T-ray time-domain spectroscopy was used for inspecting and evaluating physical property and defect characteristics in FRP composite material. Also, general refraction and transmission mode of this T-ray spectrography was used for finding refraction coefficient (n) and for obtaining T-ray image. First, in order to obtain the terahertz ray refraction index, refractive and transmission mode technique was induced, with which refraction index of GFRP composites, balsa and epoxy of wind turbine blade could be obtained. In GFRP and CFRP composites, T-ray propagation faces hindrance by carbon fiber. Accordingly, the authors have analyzed directional dependence between E-field of T-ray and the carbon fiber. Also, evaluating method of wind turbine blade composites having two (2) saw-blade delaminations integrally inserted was presented in this study. It was found that the time of flight of T-ray using T-ray transmission mode technique coincides well with that using refractive index in the wind turbine blade.

FRP 복합재료의 온도변화 및 제작인자별 비선형 전단거동 조사

복합재료의 경우 다양한 재료에 따라 제작이 가능하며 이들 완성재료의 경우 다양한 재료특성을 나타낸다. 이 연구는 건설용 FRP복합재료의 재료특성 중 선형거동이 뚜렷이 나타나는 인장, 압축과는 달리 비선형 거동이 발생되는 전단거동 특성에 대한 실험적 연구로서 ASTM D4255 규정에 의한 2-Rail 전단시험 방법을 토대로 각각의 시편들을 제작, 실험결과를 분석하였다. 고려된 실험변수로는 함침 수지류의 종류와 섬유 체적비, 섬유배열 방향 및 온도 특성, 공장용 생산제품의 균질성 등을 고려하였다. 섬유배열 방향에 따른 특성조사의 경우 섬유 배열방향을 <TEX>$0^{\circ}$</TEX>, <TEX>$30^{\circ}$</TEX>, <TEX>$45^{\circ}$</TEX>, <TEX>$60^{\circ}$</TEX>로 각각 시편을 제작하였으며, 온도에 따른 외부환경 변화에 의한 FRP재료의 전단거동을 조사하기 위하여 실험온도를 <TEX>$25^{\circ}C$</TEX>, <TEX>$40^{\circ}C$</TEX>, <TEX>$60^{\circ}C$</TEX>, <TEX>$80^{\circ}C$</TEX>로 각각 고려하여 시험을 수행하였다. 이 연구를 통하여 대부분의 복합재료 시편에서 비선형 전단거동이 확인되었으며 비닐에스테르수지를 사용하고, 높은 섬유체적비와 <TEX>$45^{\circ}$</TEX>의 섬유배열방향을 가진 시편에서 비선형 전단거동이 가장 두드러지게 나타나는 것으로 조사되었다. 온도변화에 따른 실험결과의 경우, 온도가 증가함에 따라 전단 내 비선형 거동의 감소가 나타났으며 공장용 제작제품의 경우 hand lay-up 제작시편에 비하여 비선형 전단거동이 비교적 동등하게 나타냈다. In the case of composite material, a variety of characteristics were expressed depending on the materials that were composed of. In this study, the materials showing non-linear shear behavior were investigated among FRP composite. Each specimen was designed and analyzed according to ASTM D4255 method: regulations on the 2-rail. The dependent variables included in this experiment were a variety of fiber, fiber volume ratio, fiber array direction, temperature, material homogeneity. For determination of characteristics based on the fiber array, fiber array direction of 0, 30, 45, and 60 degrees were selected for test specimen. Temperature of 25, 40, 60, and <TEX>$80^{\circ}C$</TEX> were considered for investigation of FRP materials'shear behavior based on the external temperature. Nonlinear shear behavior was observed throughout the FRP composite material in this study. Also, using vinyl ester resins, high fiber volume ratio, and fiber array direction of 45 degree appeared to show the most prominent nonlinear shear behavior. As for the findings related to the temperature change, non-linear behavior was decreased as the external temperature increased. For factory manufactured product, non-linear behavior was relatively at parity in comparison to the behavior found in the hand lay-up FRP composite specimen.

지하터널의 기둥보강에 따른 내진성능평가에 대한 해석적 연구

Due to the recent earthquakes, more interests have been focused on the retrofitting of existing structures. Especially, FRP composite material is actively used in the seismic resting design. Usually the destruction and damage of the under ground tunnel causes much impact to the social system since it contains a lot of life lines including subway, power and water lines, and so on. However, the retrofitting is more difficult due to the spacial limitation. The numerical simulation of underground tunnel using FE analysis can provide some guideline for the retrofitting rather than the experimental approach which is not simple and very expensive. In this study, the underground tunnel is evaluated through the nonlinear push over analysis and nonlinear dynamic analysis with modeling of soild as infinite elements.

기둥의 내진성능 향상을 위한 섬유보강 복합체의 적용성에 대한 해석적 연구

최근 발생한 대규모 지진으로 구조물의 내진보강에 대한 사회적 관심도가 높아지고 있다. 내진성능 향상을 목적으로 FRP 복합재료의 사용성에 대한 연구 및 개발이 활발히 진행되고 있다. 복합재료를 사용한 내진보강재는 강성과 연성을 가진 재료이어야 하므로 복합재료 보강재 설계 시 강성재와 섬유의 선택이 중요한 변수이다. 내진성능 향상을 위한 섬유보강 복합재료의 최적조합을 인장 테스트를 통하여 선정하였다. 선정된 섬유보강 복합재료 보강재를 실제 구조물에 적용하기 위하여 실제 기둥부재에 보강하는 것을 가정하여 유한요소 해석하였다. 유한요소 해석을 통하여 구조물의 내진성능 향상효과를 변위-하중 관계를 통하여 평가하였다. 섬유보강 복합재료 보강재를 사용할 경우 구조물의 내진성능이 증가한다는 해석적인 연구 결과를 도출하였다. As increasing number of large-size earthquake around Korean peninsula, many interests have been focused to the earthquake strengthening of existing structures. Fiber reinforced plastic composite material is one of strengthening material widely used to increase seismic performance of structures. It should have high stiffness as well as large ductility to provide best strengthening result. Thus selection of stiffener and fiber in composite is of important. In this study, the optimal combination of fiber and stiffener is selected with variety of tensile tests. In order to investigate performance of chosen composite material, several finite element analyses are performed with proposed FRP composite material for existing RC columns. It is discussed that the seismic performance of strengthened columns through the load-displacement relationship. It is shown that the proposed composite material can increase the strength as well as ductility of exiting RC columns.

A method for flexural reinforcement of old wood beams with CFRP materials

This paper presents a study on the reinforcement of existing wood elements under bending loads through the use of FRP materials. An analytical investigation was first conducted on the behavior of a generic FRP-reinforced wood section. This study, in turn, led to a numerical procedure based on non-linear wood properties, suitable for application in the design of FRP reinforcement of old, pre-existing wood beams under varying configurations of intervention layouts and materials. An experimental programme based on a four-point bending test configuration is proposed to characterize the stiffness, ductility and strength response of FRP-wood beams. Mechanical tests on the reinforced wood showed that external bonding of FRP materials may produce increases in flexural stiffness and capacity. The FRP composite material was made of High Tensile Carbon monodirectional reinforcing fabrics embedded in an epoxy resin matrix. This reinforcing method can be applied without necessitating the removal of the overhanging part of the pre-existing wood structure, thus maintaining the original historical structure. In addition, a beam non-linear model was proposed to predict ultimate load. At the end of this paper results of the experimental programme are presented and used for comparison with the numerical procedure.