• Title/Summary/Keyword: Epoxy-based composite

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Patch Plate Repair Method for Steel Structures Combining Adhesives and Stud Bolts

  • Ishikawa, T.;Ikeda, T.
    • International journal of steel structures
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    • v.18 no.4
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    • pp.1410-1419
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    • 2018
  • Recently, a repair method by bonding patch plates is being applied to corroded steel structures. However, one of the issues of patch plate bonding repair is the brittle debonding of the patch plates. Generally, when the delamination of the patch plates occurs, the composite effect acting between the steel members and patch plates abruptly decreases. Therefore, to prevent the brittle debonding of the patch plates, a repair method combining an adhesive and stud bolts is proposed. Till date, tensile and compressive tests have been performed for the proposed method. In this study, plate bending tests were conducted to verify the effectiveness of this method under bending conditions. Furthermore, two types of epoxy resin-based adhesives were prepared to evaluate the effectiveness of the proposed method with different adhesive properties. The test results show that the proposed method is able to prevent the brittle debonding of the patch plates in the case of both epoxy resins.

The Effect of Bias and Shear Angles on Compressive Characteristics of Carbon/Epoxy Plain Weave Fabrics (편향각과 전단각이 탄소섬유/에폭시 평직 복합재료의 압축특성에 미치는 영향)

  • Kim Sung-Jip;Chang Seung-Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.7 s.250
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    • pp.857-864
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    • 2006
  • Various compressive specimens were fabricated using autoclave do-gassing moulding to find out the compressive characteristics of the carbon/epoxy plain weave fabric composites with respect to the bias and shear angles. The stacking angles of the bias specimens are $[0]_{10T,}\;[3]_{10T,}\;[6]_{10T,}\;[9]_{10T,}\;[12]_{10T,}\;[15]_{10T,}\;[30]_{10T,}\;[45]_{10T}$ and those of the sheared specimens are $[{\pm}37]_{10T,}\;[{\pm}32]_{10T,}\;[{\pm}28]_{10T,}\;[{\pm}22]_{10T,}$ respectively. In order to verify the effect of micro-tow structures on compressive strength and modulus of the composites, compressive test specimens of uni-directional carbon/epoxy composites with the same materials and the same stacking conditions were fabricated. The modulus and strength of both types of composite specimens were compared with the prediction results based on the CLPT and a proposed strength formula. The tow deformation and fracture modes were investigated by microscopic observation.

Carbon rich fly ash and their nanostructures

  • Salah, Numan;Habib, Sami S.;Khan, Zishan H.;Alshahrie, Ahmed;Memic, Adnan;Al-ghamdi, Attieh A.
    • Carbon letters
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    • v.19
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    • pp.23-31
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    • 2016
  • Carbon rich fly ash was recently reported to have compositions that are ideal for use as a precursor and catalyst for carbon nanotube growth. This fly ash powder is mostly composed of pure carbon, predominantly present as sp2. In this work, the effect of sonication time on the morphology and structural properties of carbon rich fly ash particles is reported. The obtained results show that ultrasound treatment is an effective tool for producing ultrafine particles/fragments with higher porosity, which might be suitable for the adsorption of gasses. Moreover, carbon nanoparticles (CNPs) of this fly ash were produced in parallel using the ball milling technique, and were evaluated as reinforcements for epoxy based composites. These CNPs have almost spherical shapes with particle sizes of around 30 nm. They were found to have strong C=O carbonyl group bonds, which might be generated during the ball milling process. The tensile testing results of a fly ash CNP reinforced epoxy composite showed significant improvements in the mechanical properties, mainly in the stiffness of the polymer. The stiffness value was increased by around 23% of that of neat epoxy. These CNPs with chemically active groups might also be useful for other applications.

Acoustic Emission during Crack Propagation Process of Rubber-Modified Epoxy Resin (고무변성 에폭시 수지의 균열진전과정과 음향방출 특성)

  • 이덕보;김현수;최낙삼;남기우;문창권
    • Composites Research
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    • v.16 no.4
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    • pp.44-50
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    • 2003
  • The damage zone around a crack tip occurring before the fracture is a significant domain. which affects the toughening mechanism of materials. In this study. the growth process of damage zone in the vicinity of crack tip for rubber-modified epoxy resin is investigated using an acoustic emission(AE) analysis. The weight fractions of rubber(CTBN 1300$\times$B) in rubber-modified epoxy resin are 5 wt% and 15 wt%. The fracture toughness($K_{IC}$) and the fracture energy($G_{IC}$) were measured using 3 point bending single-edge notched specimens. The damage zone and rubber particles distributed around the crack tip were observed by a polarized optical microscope and an atomic force microscope(AFM). The damage zone around crack tip of rubber-modified epoxy resin was formed at 13 % loading and developed until 57 % loading of the fracture load. The crack initiated at 57 % loading grew repeatedly in the stick-slip propagation behavior. Based on time-frequency analysis, it was confirmed that AE signals with frequency bands of 0.15~0.20 MHz and 0.20~0.30 MHz were generated from cavitation and stable/unstable cracking inside the damage zone.

A New Mixing Method of SiC Nanoparticle Reinforced Epoxy Composites with Large Concentration of SiC Nanoparticle (대용량 SiC 나노입자 강화 에폭시 복합재료의 새로운 분산방법)

  • Kwon, Dong-Jun;Shin, Pyeong-Su;Kim, Jong-Hyun;Park, Joung-Man
    • Composites Research
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    • v.29 no.4
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    • pp.223-229
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    • 2016
  • SiC nanoparticles were used to increase flexural properties of polymer matrix. This study was to manufacture huge concentration SiC nanoparticle/epoxy composites and to evaluate the dispersion. During mixing SiC nanoparticle and epoxy, 20 wt% SiC nanoparticle in total composites was used with both stirrer and sonication equipment together. Mixing speed and dispersion were improved with the method by using both stirrer and sonication equipment at the same time via mechanical test and FE-SEM. Based on the results, modeling of SiC nanoparticle dispersion could be established. Ultimately, unidirectional carbon fiber reinforced composites was manufactured using 20 wt% SiC nanoparticle/epoxy. Mechanical property of CFRP using dual stirrer and sonication mixing method was better than composites by single sonication mixing method.

Cure Behavior and Chemorheology of Low Temperature Cure Epoxy Matrix Resin (저온 경화형 에폭시 매트릭스 수지의 경화거동 및 화학유변학에 대한 연구)

  • Na, Hyo Yeol;Yeom, Hyo Yeol;Yoon, Byung Chul;Lee, Seong Jae
    • Polymer(Korea)
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    • v.38 no.2
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    • pp.171-179
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    • 2014
  • Low temperature cure prepregs are being developed for use in the preparation of large-structured fiber-reinforced polymer (FRP) composites with good performance. Cure behavior and chemorheology of low temperature cure epoxy resin system, based on epoxy resin, curing agent, and accelerators, were investigated to provide a matrix resin suitable for the prepreg preparation. Characteristics of cure reaction were studied in both dynamic and isothermal conditions by means of differential scanning calorimetry and rheometry. The low temperature cure epoxy resin system suggested in this study as a matrix resin was curable at $80^{\circ}C$ for 3 h, and showed the gel times of 120 and 20 min at 80 and $90^{\circ}C$, respectively. Thermal and mechanical properties of the cured sample were almost the same as high temperature cure counterparts.

Laser micro-drilling of CNT reinforced polymer nanocomposite: A parametric study using RSM and APSO

  • Lipsamayee Mishra;Trupti Ranjan Mahapatra;Debadutta Mishra;Akshaya Kumar Rout
    • Advances in materials Research
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    • v.13 no.1
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    • pp.1-18
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    • 2024
  • The present experimental investigation focuses on finding optimal parametric data-set of laser micro-drilling operation with minimum taper and Heat-affected zone during laser micro-drilling of Carbon Nanotube/Epoxy-based composite materials. Experiments have been conducted as per Box-Behnken design (BBD) techniques considering cutting speed, lamp current, pulse frequency and air pressure as input process parameters. Then, the relationship between control parameters and output responses is developed using second-order nonlinear regression models. The analysis of variance test has also been performed to check the adequacy of the developed mathematical model. Using the Response Surface Methodology (RSM) and an Accelerated particle swarm optimization (APSO) technique, optimum process parameters are evaluated and compared. Moreover, confirmation tests are conducted with the optimal parameter settings obtained from RSM and APSO and improvement in performance parameter is noticed in each case. The optimal process parameter setting obtained from predictive RSM based APSO techniques are speed=150 (m/s), current=22 (amp), pulse frequency (3 kHz), Air pressure (1 kg/cm2) for Taper and speed=150 (m/s), current=22 (amp), pulse frequency (3 kHz), air pressure (3 kg/cm2) for HAZ. From the confirmatory experimental result, it is observed that the APSO metaheuristic algorithm performs efficiently for optimizing the responses during laser micro-drilling process of nanocomposites both in individual and multi-objective optimization.

Evaluation on Adiabatic Property for Vehicular Sandwich Composite Structure (차체 구조용 샌드위치 복합소재 단열 특성 평가)

  • Lee Sang Jin;Oh Kyung Won;Jeong Jong Cheol;Kong Chang duk;Kim Jeong Seok;Cho Se Hyun
    • Composites Research
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    • v.19 no.1
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    • pp.9-14
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    • 2006
  • Experimental investigation on heat transfer ratio was firstly performed with three types of sandwich panels such as the Carbon/Epoxy Skin-Aluminum Honeycomb and Balsa Core Sandwich Panel of 37mm thickness, the Carbon/Epoxy Aluminum Skin-Honeycomb Core Sandwich Panel of 57mm thickness (including insulator) and the Carbon/Epoxy Skin-Aluminum Honeycomb Core Sandwich Panel of 37mm thickness based on the KS F 2278:2003(Insulation test method of windows). In additional to this investigation, experimental tests were also done for evaluation of heat transportation ratio with the Aluminum Skin- Aluminium Honeycomb Sandwich Panels of 27mm and 35mm thickness, and Aluminum Skin-Foaming Aluminum Sandwich Panel of 27mm thickness by the KS F2277:2002 (Insulation measuring method of construction component-Calibration heat box method or protective heat box method). In this study, it was found that the larger net heat transfer cross sectional area between the skin and the sandwich core is given, the higher heat transportation ratio occurs. It was also found that the hybrid type insulation had better insulation characteristics compared to the non-hybrid type insulation.

Monitoring the water absorption in GFRE pipes via an electrical capacitance sensors

  • Altabey, Wael A.;Noori, Mohammad
    • Advances in aircraft and spacecraft science
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    • v.5 no.4
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    • pp.499-513
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    • 2018
  • One of the major problems in glass fiber reinforced epoxy (GFRE) composite pipes is the durability under water absorption. This condition is generally recognized to cause degradations in strength and mechanical properties. Therefore, there is a need for an intelligent system for detecting the absorption rate and computing the mass of water absorption (M%) as a function of absorption time (t). The present work represents a new non-destructive evaluation (NDE) technique for detecting the water absorption rate by evaluating the dielectric properties of glass fiber and epoxy resin composite pipes subjected to internal hydrostatic pressure at room temperature. The variation in the dielectric signatures is employed to design an electrical capacitance sensor (ECS) with high sensitivity to detect such defects. ECS consists of twelve electrodes mounted on the outer surface of the pipe. Radius-electrode ratio is defined as the ratio of inner and outer radius of pipe. A finite element (FE) simulation model is developed to measure the capacitance values and node potential distribution of ECS electrodes on the basis of water absorption rate in the pipe material as a function of absorption time. The arrangements for positioning12-electrode sensor parameters such as capacitance, capacitance change and change rate of capacitance are analyzed by ANSYS and MATLAB to plot the mass of water absorption curve against absorption time (t). An analytical model based on a Fickian diffusion model is conducted to predict the saturation level of water absorption ($M_S$) from the obtained mass of water absorption curve. The FE results are in excellent agreement with the analytical results and experimental results available in the literature, thus, validating the accuracy and reliability of the proposed expert system.

Shear Resistance Evaluation of Steel Grid Composite Deck Joint (격자형 강합성 바닥판 이음부의 전단내력 평가)

  • Shin, Hyun-Seop;Park, Ki-Tae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.10
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    • pp.5290-5298
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    • 2013
  • In order to apply a mechanical deck joint to the prefabricated steel grid composite decks, shear resistance of a joint composed of concrete shear key and high-tension bolt is experimentally evaluated by the push-out test. Shear resistance evaluated by the test is compared with resistance estimated by empirical and design equations based on the shear friction theory. Test results show that joint specimens bonded by epoxy have about 10% more shear resistance than specimens with strengthened shear key by steel plates, but in the case of specimens with strengthened shear key there is smaller resistance deviation than specimens bonded by epoxy. In comparison with resistances estimated by empirical and design equations, the deck joint can be safely designed. But because the existed shear resistance of deck joint is underestimated by the ACI-318, application of the LRFD design equation could be more reasonable.