Interlaminar Toughening of GFRP: Part 2 — Characterization and Numerical Simulation of Curing Kinetics

Author(s):  
Dakai Bian ◽  
Bradley R. Beeksma ◽  
D. J. Shim ◽  
Marshall Jones ◽  
Y. Lawrence Yao

Various methods of toughening the bonding between the interleaf and laminate glass fiber reinforced polymer (GFRP) has been developed due to the increasing applications in industries. A polystyrene (PS) additive modified epoxy is used to improve the diffusion and precipitation region between polysulfone (PSU) interleaf and epoxy due to its influence on the curing kinetics without changing glass transition temperature and viscosity of the curing epoxy. The temperature dependent diffusivities of epoxy, amine hardener, and PSU are determined by using Attenuated Total Reflection-Fourier Transfer Infrared Spectroscopy (ATR-FTIR) through monitoring the changing absorbance of their characteristic peaks. Effects of PS additive on diffusivity in the epoxy system is investigated by comparing the diffusivity between non-modified and PS modified epoxy. The consumption rate of the epoxide group in the curing epoxy reveals the curing reaction rate, and the influence of PS additive on the curing kinetics is also studied by determining the degree of curing with time. A diffusivity model coupled with curing kinetics is applied to simulate the diffusion and precipitation process between PSU and curing epoxy. The effect of geometry factor is considered to simulate the diffusion and precipitation process with and without the existence of fibers. The simulation results show the diffusion and precipitation depths which matches those observed in the experiments.

Author(s):  
Dakai Bian ◽  
Bradley R. Beeksma ◽  
D. J. Shim ◽  
Marshall Jones ◽  
Y. Lawrence Yao

Various methods of toughening the bonding between the interleaf and laminate glass fiber reinforced polymer (GFRP) have been developed due to the increasing applications in industries. A polystyrene (PS) additive modified epoxy is used to improve the diffusion and precipitation region between polysulfone (PSU) interleaf and epoxy due to its influence on the curing kinetics without changing glass transition temperature and viscosity of the curing epoxy. The temperature-dependent diffusivities of epoxy, amine hardener, and PSU are determined by using attenuated total reflection–Fourier transfer infrared spectroscopy (ATR–FTIR) through monitoring the changing absorbance of their characteristic peaks. Effects of PS additive on diffusivity in the epoxy system are investigated by comparing the diffusivity between nonmodified and PS modified epoxy. The consumption rate of the epoxide group in the curing epoxy reveals the curing reaction rate, and the influence of PS additive on the curing kinetics is also studied by determining the degree of curing with time. A diffusivity model coupled with curing kinetics is applied to simulate the diffusion and precipitation process between PSU and curing epoxy. The effect of geometry factor is considered to simulate the diffusion and precipitation process with and without the existence of fibers. The simulation results show the diffusion and precipitation depths which match those observed in the experiments.


2020 ◽  
Vol 24 (1) ◽  
pp. 11-16
Author(s):  
Saddam - Husein ◽  
Rudy Djamaluddin ◽  
Rita Irmawaty ◽  
Kusnadi Kusnadi

SADDAM HUSEIN. Analisa Pola Kegagalan Balok Beton Menggunakan GFRP Bar Tanpa Selimut Beton (dibimbing oleh Rudi Djamaluddin dan Rita Irmawaty) Struktur beton bertulang yang menggunakan tulangan baja pada daerah korosif, menjadi rawan terhadap kerusakan atau penurunan kekuatannya akibat korosi.Korosi pada tulangan baja merupakan salah satu faktor penyebab menurunnya kekuatan struktur beton bertulang. Salah satu material yang dikembangkan mengatasi korosi adalah penggunaan material tulangan GFRP (Glass Fiber Reinforced Polymer). Penelitian ini bertujuan untuk menganalisa kapasitas lentur dan pola kegagalan balok beton tanpa selimut dengan menggunakan material tulangan GFRP bar.   Desain penelitian merupakan eksperimental laboratorium dengan rekapitulasi sebanyak 6 sampel yang terdiri dari 2 Balok beton menggunakan tulangan baja dengan selimut beton, 2 balok beton menggunakan tulangan GFRP bar dengan selimut beton, 2 balok beton menggunakan GFRP bar tanpa selimut beton. Metode pengujian dilakukan dengan dengan pengujian lentur statik monotonik dan Analisis data menggunakan uji kondisi retak awal dan kondisi ultimit.   Hasil penelitian ini menunjukkan bahwa kapasitas lentur pada balok dengan tulangan GFRP bar lebih besar dibandingkan dengan balok tulangan baja dan mampu meningkatkan kapasitas lentur balok dalam menahan beban sebesar 39.76 %, pola kegagalan beton yang terjadi pada balok tulangan baja mengalami kegagalan lentur tekan ditandai dengan retakan yang terjadi pada sisi tertekan dan membentuk retakan tegak dengan sumbu netral beton yang tertekan, sedangkan pada balok beton tulangan GFRP tanpa selimut mengalami kegagalan keruntuhan tekan geser dengan kondisi tulangan berdeformasi (bi-linear) dengan retak miring dan secara tiba-tiba menjalar menuju sumbu netral beton yang tertekan sehingga terjadilah keruntuhan secara tiba-tiba.     SADDAM HUSEIN.Failure mode analysis of concrete Beams Using GFRP rebar Without concrete cover (supervised by Rudi Djamaluddin and Rita Irmawaty)   Reinforced concrete that uses rebar steel in corrosive areas, are prone to damage or decreased strength due to corrosion. Corrosion in the steel reinforcement is one of the factors that decreasing strength of reinforced concrete. One of the materials developed to overcome corrosion is the use of GFRP (Glass Fiber Reinforced Polymer) reinforcement material. This study aims to analyze the flexural capacity and failure mode of concrete beams without concrete cover using material GFRP bar as reinforcement.   The research design was an experimental laboratory with a recapitulation of 6 samples consisting of 2 beams using steel reinforcement with concrete cover.2 concrete beams using reinforcement GFRP bar with concrete cover, 2 beams using GFRP bars without concrete cover. The  research method uses the monotonic static flexure and analyzing the data using the initial crack condition and ultimate conditions test.   The results of the research indicate the flexural capacity of the beams with GFRP bar reinforcement is higher than steel reinforcement beams and can increase 39.76% of the flexural capacity of the beams in holding loads , the failure mode analysis occurs in steel reinforcing beam experiences compressive failure. Failure was characterized  by cracks that occur on the depressing side and form an upright crack with the neutral axis of the compressed concrete, whereas in GFRP reinforced concrete beams without concrete cover, failure of shear compression with conditions of deformed reinforcement (bi-linear) with sloping cracks and suddenly spread towards the neutral axis of the compressed concrete so that there was a sudden collapse.


2014 ◽  
Vol 1079-1080 ◽  
pp. 258-265
Author(s):  
Chen Ning Cai ◽  
Shan He ◽  
Li Na Liu ◽  
Shi Kun Ou

Thispaper presents an experimental study to strengthen an existing bridge usingpre-stressed carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer(GFRP) materials. The method using pre-stressed hybrid fiber reinforced polymer(HFRP) to strengthened structural members is an emerging pre-stressed strengtheningtechnology. In this study, experimental data selected from result of staticloading test conducted to hollow slabs with CFRP/GFRP has been compared with specimenswithout strengthening. Test results showed that the strengthening methoddeveloped in this study could effectively reduce the stress in hollow slab,improving the flexural rigidity and inhibiting the concrete from fracture.


Machines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 16
Author(s):  
Gabriel Mansour ◽  
Panagiotis Kyratsis ◽  
Apostolos Korlos ◽  
Dimitrios Tzetzis

There are numerous engineering applications where Glass Fiber Reinforced Polymer (GFRP) composite tubes are utilized, such as desalination plants, power transmission systems, and paper mill, as well as marine, industries. Some type of machining is required for those various applications either for joining or fitting procedures. Machining of GFRP has certain difficulties that may damage the tube itself because of fiber delamination and pull out, as well as matrix deboning. Additionally, short machining tool life may be encountered while the formation of powder like chips maybe relatively hazardous. The present paper investigates the effect of process parameters for surface roughness of glass fiber-reinforced polymer composite pipes manufactured using the filament winding process. Experiments were conducted based on the high-speed turning Computer Numerical Control (CNC) machine using Poly-Crystalline Diamond (PCD) tool. The process parameters considered were cutting speed, feed, and depth of cut. Mathematical models for the surface roughness were developed based on the experimental results, and Analysis of Variance (ANOVA) has been performed with a confidence level of 95% for validation of the models.


2021 ◽  
Vol 11 (8) ◽  
pp. 3429
Author(s):  
Željka Beljkaš ◽  
Nikola Baša

Deflections on continuous beams with glass fiber-reinforced polymer (GFRP) reinforcement are calculated in accordance with the appropriate standards (ACI 440.1R-15, CSA S806-12). However, experimental research provides results which differ from the values calculated pursuant to the standards, particularly when it comes to continuous beams. Machine learning methods can be applied for predicting a deflection level on continuous beams with GFRP (glass fiber-reinforced polymer) reinforcement and loaded with a concentrated load. This paper presents research on using artificial neural networks for deflection estimation and an optimal prediction model choice. It was necessary to first develop a database, in order to train the neural network. The database was formed based on the results of the experimental research on continuous beams with GFRP reinforcement. Using the best trained neural network model, high accuracy was obtained in estimating deflection, expressed over the mean absolute percentage error, 9.0%. This result indicates a high level of reliability in the prediction of deflection with the help of artificial neural networks.


Author(s):  
Priyadarsini Morampudi ◽  
Kiran Kumar Namala ◽  
Yeshwanth Kumar Gajjela ◽  
Majjiga Barath ◽  
Ganaparthy Prudhvi

Lubricants ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 22
Author(s):  
Emadelddin Hassan ◽  
Iasonas Zekos ◽  
Philip Jansson ◽  
Toa Pecur ◽  
Christophe Floreani ◽  
...  

Erosion of tidal turbine blades in the marine environment is a major material challenge due to the high thrust and torsional loading at the rotating surfaces, which limits the ability to harness energy from tidal sources. Polymer–matrix composites can exhibit leading-blade edge erosion due to marine flows containing salt and solid particles of sand. Anti-erosion coatings can be used for more ductility at the blade surface, but the discontinuity between the coating and the stiffer composite can be a site of failure. Therefore, it is desirable to have a polymer matrix with a gradient of toughness, with a tougher, more ductile polymer matrix at the blade surface, transitioning gradually to the high stiffness matrix needed to provide high composite mechanical properties. In this study, multiple powder epoxy systems were investigated, and two were selected to manufacture unidirectional glass-fiber-reinforced polymer (UD-GFRP) plates with different epoxy ratios at the surface and interior plies, leading to a toughening gradient within the plate. The gradient plates were then mechanically compared to their standard counterparts. Solid particle erosion testing was carried out at various test conditions and parameters on UD-GFRP specimens in a slurry environment. The experiments performed were based on a model of the UK marine environment for a typical tidal energy farm with respect to the concentration of saltwater and the size of solid particle erodent. The morphologies of the surfaces were examined by SEM. Erosion maps were generated based on the result showing significant differences for materials of different stiffness in such conditions.


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