Bonding Performance of Glulam Reinforced with Textile Type of Glass- and Aramid-Fiber, GFRP and CFRP

Keon Ho Kim,Soon Il Hong 한국목재공학회 2011 목재공학 Vol.39 No.2

To evaluate the bonding performance of reinforced glulam, the textile type of glass fiber and aramid fiber, and the sheet type of glass fiber reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP) were used as reinforcements. The reinforced glulam was manufactured by inserting reinforcement between the outmost and middle lamination of 5ply glulam. The types of adhesives used in this study were polyvinyl acetate resins (MPU500H, and MPU600H), polyurethane resin and resorcinol resin. The block shear strengths of the textile type in glass fiber reinforced glulam using MPU500H and resorcinol resin were higher than 7.1 N/mm2, and these glulams passed the wood failure requirement of Korean standards (KS). In case of the sheet types, GFRP reinforced glulams using MPU500H, polyurethane resin and resorcinol resin, and CFRP reinforced glulams using MPU500H and polyurethane resin passed the requirement of KS. The textile type of glass fiber reinforced glulam using resorcinol resin after water and boiling water soaking passed the delamination requirement of KS. The only GFRP reinforced glulam using MPU500H after water soaking passed the delamination requirement of KS. We conclude that the bonding properties of adhesive according to reinforcements are one of the prime factors to detennine the bonding performance of the reinforced glulam.

Interlaminar fracture toughness of CFRP laminates with silk fibers interleave

정종설,정성균 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.12

Interlaminar fracture toughness of CFRP laminates with silk fibers interleave was evaluated in this paper. Silk fibers were obtained from silkworm cocoon. Long silk fibers were wound around a bobbin and cut into specimen size. Resin films were bonded on both sides of a sheet of silk fibers. Silk fibers with resin films were put between [012] and [012] and cured by following the curing process. Evaluation of mode I and mode II interlaminar fracture toughness was accomplished by DCB and ENF test, respectively. Mode I interlaminar fracture toughness of CFRP laminates with silk fibers interleave was 59% higher than that of CFRP. Mode II interlaminar fracture toughness of CFRP laminates with silk fibers interleave was 44% higher than that of CFRP. It seems that CFRP laminates with silk fibers interleave will be useful to structures which need high interlaminar fracture toughness.

Feasibility of concrete-filled fiber-reinforced plastic piles for deep foundation: a comprehensive review on geotechnical and structural characteristics

이학성,최만권,김병주 한국탄소학회 2024 Carbon Letters Vol.34 No.1

Traditional piles used for deep foundation, such as steel, concrete, and timber, are susceptible to corrosion and a reduction in structural capacity over time. This has led to the development of new materials like concrete-filled FRP piles (CFFP). CFFP is a composite pile filled with concrete and covered with a fiber-reinforced plastic (FRP) shell, providing non-corrosive reinforcement and protection to the concrete. As a result, CFFP is a highly promising candidate for implementation in various fields due to its structural advantages and necessity. Compared to traditional concrete piles, CFFP can be installed with less damage and a lower blow range due to its elastic modulus, damping ratio, and specific weight. The bearing capacity of a pile is influenced by various factors, including its stiffness, residual stress, and axial load resistance. Due to competitive pricing, glass fiber has been widely utilized, and there is a growing interest regarding carbon-fiber-reinforced concrete piles due to the excellent mechanical properties of carbon fiber. The remarkable stiffness and strength attributes of carbon fibers are evident in CFRP-confined piles, which present a notably wide range of load-bearing capacities, boasting an ultimate axial load capacity ranging from 500 to 4000 kN. Furthermore, CFFPs have been confirmed to have superior lateral load resistance compared to conventional piles, attributed to the reinforcement provided by FRP materials. Conventional piles face a challenge in that their structural characteristics deteriorate in the corrosive marine environment, with a projected lifespan of less than 20 years. In contrast, the service life of CFFPs is estimated to range from 50 to 75 years.

탄소섬유 드레이핑 및 수지 유동 해석을 통한 CFRP 제조용 RTM 금형 설계

최광묵,채홍준 한국금형공학회 2019 한국금형공학회지 Vol.13 No.1

This paper presents the design strategy for the optimal RTM molds of Carbon Fiber Reinforced Plastic (CFRP) by carbon fiber draping and resin flow simulation. First, the mold shape and molding condition were determined considering the undercut and die face of the product in the draping simulation, which made the preliminary shape of the product by compressing the carbon fiber. After that, the diffusion behavior during the injection of resin in the mold was predicted by the resin flow simulation. Finally, the optimal mold shape was designed by selecting the locations of resin injection port and vent based on total results of simulations. In this paper, the mold of automotive side mirror case was selected as the representative product. Also, the actual mold was manufactured based on the simulation design to confirm the practicality of it. This study is expected to contribute to the industry as a technology to improve the reliability and productivity of CFRP producted by RTM process.

탄소섬유 복합재료 구조부재 물성 획득 및 원형부재 충격 전산모사

나승우,김대영,신광수,김지훈 조선대학교 공학기술연구원 2022 공학기술논문지 Vol.15 No.2

Carbon Fiber Reinforced Plastics (CFRP) is composed of carbon fiber and resin. Carbon fiber has superior strength and stiffness and is lighter than primary light metals. When CFRP is applied to structural parts, these general mechanical properties depend on the orientation of the carbon fiber. The mechanical properties of CFRP are obtained through material testing, such as applying tension or compression in different fiber directions. In this study, the physical properties of CFRP were acquired to investigate the impact characteristics of structural members to which CFRP with different layer structures was applied through impact tests and simulations, and based on this, an impact simulation was performed on circular structural members. Three failure criteria were applied to investigate the collapse behavior due to impact loading in the finite element model of the simulation. Moreover, the simulation results according to each failure criterion were compared and considered.

Investigation of Formability and Fiber Orientation in the Square Deep Drawing Process with Steel/CFRP Hybrid Composites

이민식,김성진,서형윤,Chung-Gil Kang 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.11

Recently, vehicle parts such as center pillars and impact beams used in automobiles have been requiring materials that satisfy both high strength and impact absorption. Therefore, in this study, the applicability of the forming process of CR340 (cold rolled steel sheet)/carbon fiber reinforced plastic (CFRP) hybrid composites which are a bonded material of cold rolled steel sheet having excellent formability and carbon fiber prepreg having high strength and high collision absorption in the vehicle parts was investigated. Hybrid composites are fabricated by stacking CFRP prepreg on a cold rolled steel sheet (CR340) with Zn coating. Bonding materials were used at the interface between the CFRP prepreg and steel sheet. This study investigated the formability and fiber orientation of CR340/CFRP hybrid composite after deep drawing. Square cup deep drawing tests were conducted with various process parameters to evaluate the formability of CR340/CFRP hybrid composite. The square deep drawing process parameters and the thinning rate at each position of the drawing product were measured, and the various problems encountered during the deep drawing process were reviewed with the thermal flow of epoxy. Experimental data between the forming depth and blank holding force was introduced with CFRP/CR340 with Zn coating sheet hybrid composite. The thickness variations of the materials and the fiber orientations were observed using cross sections at each position. Void and delamination defects were observed at the die round and were discussed in detail.

EFFECT OF THE FIBER LAMINATION ANGLE OF A CARBON-FIBER, LAMINATED COMPOSITE PLATE ROOF ON THE CAR INTERIOR NOISE

Sungil Bang,Yoojin Park,Yeonsoo Kim,Tae Jin Shin,Jiseon Back,이상권 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.1

The paper presents the change of the interior noise according to the lamination angles of the carbon fiber in the carbon-fiber reinforced plastic (CFRP) laminated composite plate. In the previous paper, the charateristics of the sound radiated from a CFRP plate was studied in the free field condition. In this paper, vibro-acoustic interaction for the CFRP plate with various lamination angles was studed considering the application of the CFRP plate to car roof. In order to study the vibro-acoustic interaction, a certain enclosure with flexible wall was required and then the closed rectangular box was prepared. The one flexible wall of the rectangular box consisted of CFRP plate. Three CFRP plates with fiber lamination angles of [−15/15/15/−15]s, [−30/30/30/−30]s, and [−75/75/75/−75]s were fabricated and used as one flexible wall of the closed box. These plates were excited by an impact force, and the interior sound pressure within the closed box was calculated both theoretically and experimentally. Then, the identified vibro-acoustic characteristics were used to apply the CFRP plate to the roof of a car, thereby shifting the resonance frequency of the interior noise.

SENT시험편을 이용한 CFRP/GFRP 하이브리드 적층재의 노치선단부 변형률 평가

강지웅 ( Ji Woong Kang ) 한국안전학회(구 한국산업안전학회) 2014 한국안전학회지 Vol.29 No.5

The aim of this work is conduct the study on light weight and structural performance improvement of the composite windpower blade. GFRP (Glass Fiber Reinforced Plastic) pre-empted by CFRP(Carbon Fiber Reinforced Plastic), the major material ofwind power blade, was identified the superiority of mechanical performance through the tensile and fatigue test. SENT(Single EdgeNotched Tension) specimen fracture test was conducted on the specimen that laminated together 2 ply CFRP with 4 ply GFRP throughDIC(Digital Image Correlation) analysis. The SENT specimen thickness and a0/W ratio is 1.45 mm and 0.2, respectively. The fracturetest accomplished with displacement control with 0.1 mm/min at the room temperature. The experimental apparatus used for thefracture test consisted of a 50kN universal dynamic tester and CCD camera connected to a personal computer (PC), which was used torecord images of the specimen surface. Following data acquisition, the images and load-displacements were transferred to the PC, onwhich the DIC software was implement. The experiment and DIC analysis results show that CFRP/GFRP laminated composite exhibitsimprovement of the strength, compared with that of the existing blade material. This study shows the result that the strength of CFRProtor blade of wind turbine satisfies through the experimental and DIC method.

공기결합 초음파탐상에 의한 CFRP 복합재의 흡습 특성 평가

이주민(Joo-Min Lee),이주성(Joo-Sung Lee),김용권(Yong-Kwon Kim),박익근(Ik-Keun Park) 한국비파괴검사학회 2014 한국비파괴검사학회지 Vol.34 No.2

탄소섬유강화 복합재료(carbon fiber reinforced plastics; 이하 CFRP)는 금속재료에 비해 중량이 가벼우면서도 비강도와 비강성이 높은 재료로 항공기, 자동차, 선박 등의 다양한 분야에서 적용이 증가하고 있다. CFRP는 정적부하에 대해서는 우수한 역학적 특성을 가진 반면에 고온·다습한 환경에서는 우수한 역학적 특성을 기대할 수 없고, 복합재료의 유용한 기계적 성질이 장시간 주위 환경에 놓여 있어도 충분히 유지되어야 하지만 온도, 습도 등과 같은 환경적 요인으로 수분이 복합재료 내로 침투하여 기지의 분자 배열 및 화학적 성질을 변화시키고 복합재료의 계면 특성 및 구성 재질의 기계적 성질을 저하시킨다. 항공기의 경우 운항 시에 CFRP가 고온 다습한 환경조건에 장시간 노출되게 되면 CFRP 내부로 수분이 흡수되게 되는데 CFRP 내부에 흡수된 수분은 체적팽창을 야기시키고 내부 응력상태를 변화시킬 뿐만 아니라 섬유와 기지의 화학적 결합을 분리시킴으로써 접합강도를 급격히 저하시키게 된다. 따라서 CFRP를 사용하는 항공기의 구조 건전성확보를 위하여 실제 환경에서의 특성 변화를 연구할 필요가 있다. 본 연구에서는 공기결합 초음파탐상검사(air coupled ultrasonic testing; 이하 ACUT) 시스템을 이용하여 흡습된 CFRP의 비파괴적 특성을 평가하고자 하였다. CFRP 시험편을 직접 제작한 후 고온다습한 환경을 설정하기 위해 항온수조를 이용하여 75℃의 증류수에 30일, 60일, 120일간 침지하였고, ACUT를 이용하여 흡습에 의한 CFRP 시험편의 특성 변화를 초음파C-scan 이미지와 흡습 전과 후의 신호의 전파시간 변화를 통해 초음파 신호 특성 변화를 고찰하였다. 또한 전단강도 평가를 통해 흡습에 의한 기계적 특성 변화를 실험적으로 검증하였다. Carbon-fiber-reinforced plastic (CFRP) composites are increasingly being used in a variety of industry applications, such as aircraft, automobiles, and ships because of their high specific stiffness and high specific strength. Aircraft are exposed to high temperatures and high humidity for a long duration during flights. CFRP materials of the aircraft can absorb water, which could decrease the adhesion strength of these materials and cause their volumes to change with variation in internal stress. Therefore, it is necessary to estimate the characteristics of CFRP composites under actual conditions from the viewpoint of aircraft safety. In this study air-coupled ultrasonic testing (ACUT) was applied to the evaluation of water absorption properties of CFRP composites. CFRP specimens were fabricated and immersed in distilled water at 75℃ for 30, 60, and 120 days, after which their ultrasonic images were obtained by ACUT. The water absorption properties were determined by quantitatively analyzing the changes in ultrasonic signals. Further, shear strength was applied to the specimens to verify the changes in their mechanical properties for water absorption.

Design and testing of CFRP sleeve for a high-speed permanent magnet synchronous motor with surface-mounted rotor

Yong Zhou,Lei Tian,Sheng-Hua Gao,Jing-Wei Zhang,Lin-Ke Yang,Rui-Guang Xie 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.1

A high-speed (HS) permanent magnet (PM) synchronous motor (HSPMSM) with a carbon fiber-reinforced plastic (CFRP) protective sleeve in the surface-mounted rotor was explored in this study. In view of retaining the PMs at HS operations, the high-strength CFRP sleeve was designed on the basis of a process that could be summarized as follows. First, a multi-physics analysis of the rotor was conducted. The requirements to the CFRP sleeve were obtained from electromagnetic analysis, loss analysis, heat flow coupling computational fluid dynamics analysis, structural analysis, and rotor dynamics analysis. Second, the CFRP sleeve was designed by theoretical analysis. From the results, the thickness values of the carbon fibers in the circumferential and helical directions were chosen to be 4 and 1 mm, respectively, while the helical angle of carbon fibers was chosen to be 70°. Then, a plateshaped CFRP product and a cylindrical CFRP product were fabricated to verify the strength and stiffness of the CFRP sleeve. The performance test results show that the hoop strength and elastic modulus and the axial strength and elastic modulus of the plate-shaped CFRP products at 20 °C are 1963 MPa @ 156 GPa and 550 MPa @ 36 GPa, respectively. The hoop strain and axial strain of the cylindrical CFRP product under 35 MPa are about 3000 and 1900 με, which meet the design requirements of the HSPMSM.