Theses supervised by Doç. Dr. Ahmet Erkliğ
10 theses · Gaziantep University
A research on effect of pistachio shell on the mechanical properties of composite material
In the current study, the effect of micro-scale content of natural particle (pistachio shell) on the mechanical properties of polyester matrix composites is experimentally investigated. The particle contents of pistachio shell are 0, 5, 10, 15, 20 and 25 wt%. The tensile, flexural, and charpy impact tests were carried out on the moulded composite specimens according to ASTM and ISO standards. Good dispersion of pistachio shell particles in polymer matrix was observed using SEM micrographs. It is observed that the mechanical properties of polyester composite is increased with the increasing of pistachio shell particle content. The highest tensile strength, flexural strength, and impact strength was obtained at pistachio shell particle content of 10, 5, and 5 wt%, respectively.
Investigation of effect of borax particles on bonding and strength of adhesively bonded composites
In this study, the influence of microscale particles borax filler dispersion in the epoxy adhesive on tensile test, three point bending test of adhesively bonded single-lap and double-lap joints were experimentally investigated. Borax filler was used as additive material within the epoxy, having different mass ratios (5, 10, 15, 20, 25% wt.). Test samples were produced by plain woven S-glass fiber. Tensile test and three point bending tests were applied for single lap joint. According to the result of tensile test the maximum shear strength increased by 28.84% compared with pure epoxy at weight rate of borax 15%, and beyond that ratio it tends to decrease. According to the result of three point bending test the maximum strength increased by 13.86% compared with pure epoxy at weight rate of borax 15% , and beyond that ratio it tends to decrease. Only tensile test was applied to the double-lap joints. According to the result of tensile test the maximum strength increased by 43% compared with pure epoxy at weight rate of borax 25%. By these results it can be said that the best ratio of borax that can be used as additive material within the epoxy to improve the shear strength for single and double-lap joints are 15% - 25% respectively, in addition, reducing the cost of materials used.
A research on effect of sewage sludge ash on the bonding properties of composite materials
Adhesive bonding has considerable advantages over mechanical fasteners. Adhesively bonded joints have more fatigue resistance because of absence of stress concentrations that occurs at fasteners. Therefore, the need to improve adhesives used for bonding has acquired utmost importance. The present study aims to strengthen adhesive joints. Single lap and double lap configurations were chosen to perform this study. In order to improve the mechanical properties of adhesively bonded joints, micro-particles (45μm and below) of sewage sludge ash (SSA) were mixed with epoxy resin. The weight ratios of SSA added into epoxy were (0%, 5%, 10%, 15%, 20%, 25%) respectively. Glass fiber/epoxy composite laminates with 10 layers were chosen as adherends and the adhesive was produced from different amounts of microparticles added into the epoxy. The adhesively bonded joints with same thicknesses of adherends under tensile and bending loads were investigated experimentally to assess the effect of SSA particles on the mechanical properties of the epoxy. Depending on the tensile test results, the addition of SSA increased shear stress at specified weight ratios of ash. It was found that addition more than 20% of ash particles into the adhesive showed a negative effect on shear stress. According to the three point bending test results, flexural stress affected by addition of SSA particles.
Investigation of the effect of nanoparticles on adhesion of single lap joints in composites
Adhesively bonded joints of fiber-reinforced polymer structural components offer numerous advantages, including high strength and high stiffness-to-weight ratios, good fatigue and corrosion resistance, and high-energy absorption capacity, all of which make them more efficient compared to mechanical fasteners. Many techniques have been used to strengthen ABJs such as use of fillers, hybrid joints, and co-cured joints. The vast majority of studies have been focused on using filler materials for technical and economical reasons. In this study, three types of Nano-fillers (Nano-clay, Nano-silica and Nano-graphene) were used to reinforce epoxy resin. Based on weight content of epoxy; clay, silica, and graphene were added by (1, 2, 3, and 5 %), (1, 2, and 3 %), and (0.1, 0.2, 0.3, 0.4, and 0.5 %), respectively. Glass fiber reinforced polymer plates produced commercially were used as adherends. The experimental results obtained from lap shear test and 3-point bending test, have demonstrated that the three types of Nano-fillers positively affected the joint strength. The highest improvement in shear and flexural strength was obtained by adding graphene particles as 145% and 100%, respectively. As the joint strength increased with the Nano-particle inclusion, the adhesive failure mode of the neat epoxy joints was changing to more and more progressive mode. The most important failure mode was observed in the fracture surfaces of the joints prepared with graphene particles.
Mechanical properties of nano-silica particulate jute/glass fiber hybrid composites
Çevre dostu malzemeler için artan talep ve geleneksel elyafın maliyetinin azaltılma isteği doğal elyaf kompozitlerinin popülaritesinin artmasına yol açmaktadır. Kompozit malzemelerde kullanılan doğal lifler, düşük yoğunluk, uygun mukavemet gibi bazı önemli avantajlara sahiptir. Doğal elyaf kompozitlerin mekanik özellikleri sentetik elyaf kompozitlerden çok daha düşüktür, ancak üstün ve ekonomik bir kompozit geliştirmek için doğal bir elyaf ile bir sentetik elyaf aynı matriks malzemesinde kombine edilebilir ve böylece her iki lifin en iyi özellikleri birleştirilebilir. Bu çalışmada jüt, cam ve hibrit jüt / cam elyaf nano-silis parçacık dolgulu epoksi matriks lamine kompozitlerin gerilme, eğilme ve çarpma özellikleri incelenmiştir. Nano-silika içeriği oranları epoksi'de %1, %2 ve %3'tür. Hibrit konfigürasyonlar G8, G1J6G1, J3G2J3, J2G1J2G1J2 ve J8 olarak üretildi. Kompozit laminatlar elle yatırma yöntemi üretildi. Charpy darbe testleri ISO 179/92 standardına göre yapıldı, ASTM D638-10 standardına göre çekme testleri yapıldı ve ASTM D790-10 standardına göre bükme testleri yapıldı. Çekme, eğilme ve darbe testlerinin sonuçları, nano-silika içeriğinin %2'lik oranının tüm hibrit ve hibrit olmayan konfigürasyonlar için en iyi değerleri verdiğini göstermiştir.
Investigation of impact behavior of the nano-scaled particle filled hybrid composite plates
The present study aims to investigate the ability of graphene nanoplatelets (GnPs) inclusion effects on mechanical (tensile and flexural) and low-velocity impact (LVI) characteristics of glass, aramid, basalt and carbon fiber reinforced hybrid/non-hybrid composites. A high speed of mechanical stirrer was used for mixing of epoxy with GnPs particles at different GnPs weight contents (0, 0.1, 0.25, and 0.5 wt %), and the mixture of the GnPs enriched resin was applied to the fiber fabrics for different lay-up conditions by using the hand-layup and vacuum assisted hand lay-up method. Impact tests were performed by using a drop weight impact machine at the impact energy of 30J, and load to time/displacement history responses were evaluated and reported. Damage characteristics of the composite samples after the low-velocity impact tests were characterized and compared according to GnPs contents. In this way, the combined effects of GnPs loading and glass/aramid, glass/basalt, glass/carbon fiber hybridizations were investigated in detail. Results showed from this study that incorporation of GnPs particles at the certain concentrations significantly affected the impact resistance and mechanical properties of fiber reinforced hybrid/non-hybrid composites. However, excessive GnPs particle addition into the epoxy resin caused a reduction in mechanical and impact properties as a result of particle agglomeration with reducing load transferring from particle to matrix resin.
Mechanical properties of graphene nano-plates reinforced ldpe composites
In this thesis, the effects of graphene on the mechanical properties of low density polyethylene (LDPE) film used in packaging industry are investigated. Graphene was added to the LDPE F2-12 raw material in 0.1%, 5% and 10% by weight. The mixture prepared by twin screw extrusion machine was filmed in blown line. Film thickness was obtained as 17, 19, 25 and 27µ due to the effect of graphene addition. Thickness, heat seal, tear, coefficient of friction (COF) and tensile strength tests of the produced films were carried out in accordance with ASTM standards. When the graphene additive test results were examined in LDPE film 58.82% increase in thickness was observed. It was observed that the mechanical properties of LDPE film which was added graphene generally decreased and the film was found to be weakened compared to the non-graphene film. When a mechanical compound is tried to be combined with a standard compound twin screw machine, no chemical bond is formed between the components, since maleic anhydride is not the binding raw material, the resulting filmed dispersion has not been dispensed and regional differences have occurred.
Effects of nanographene particles on hybrid composites
Because of the great attention of researchers with composite materials, the studies deal with them are increasing day to day to satisfy the requirements of various industrial applications. A novel class of nano fillers newly discovered is graphene which had captured the attention of researchers recently due to unique features such as high absolute strength, tensile modulus, high aspect ratio, and high surface area. The present investigation was basically performed to highlight the influence of Graphene Nano-platelets (GNPs) on tensile strength, flexural strength, impact resistance and vibration properties of carbon-glass fiber/epoxy hybrid and non-hybrid composite laminates. GNPs were dispersed with different weight contents of 0.1, 0.25 and 0.5 %wt. within epoxy matrix. All tests with and without GNPs fillers were performed comparatively. From the experimental results, it can be said that the addition of GNPs into epoxy matrix has a considerable effect on the mechanical performance of the hybrid composite laminates. The improved strength refers to high bonding between GNPs, epoxy and fibers at the interphase. Key word: Graphene Nano-platelets, impact resistance, tensile strength, flexural strength, vibration
Vibration damping propertiy, tensile and flexural behaviour of kevlar-carbon/epoxy/nanographene composite
In this study, the impact, tensile, vibration and flexural properties of Kevlar, carbon and hybrid Kevlar/carbon filled epoxy with nanographene matrix based composite laminates were investigated. Multi configurations were fabricated as (C8, C2K4C2, K2C4K2, and K8) were investigated by Charpy impact, vibration, tensile and flexural test. The composite laminates were fabricated by hand lay-up process. The Charpy impact test of fabricated composite laminates was conducted following ISO 179/92 standard by Köger 3/70 Charpy impact test machine. The vibration test were conducted by ASTM E756. The tensile and flexural tests were conducted by following ASTM D638-10 for uniaxial tensile and ASTM D790-10 for three-point bending. The results of vibration showed the best ratio of nanographene was 0.1 % wt. for all configurations. Also the results of tensile stress showed the ratio of nanographene that 0.1 % wt. give best value for all configurations. But flexural strength and flexural modulus results of K8 and C8 show the best ratio of nanographene were 0.5 % wt. As well as the results of impact energy showed the best ratio of nanographene was 0.25 % wt. for all configurations. Key Words: Charpy Impact, Tensile, Flexural, Vibration, Kevlar fiber, Carbon fiber and nanographen.
Hybridization effects on tensile and flexural behavior of laminated composite plates
In this study, the influence of hybridization with different stacking configurations on tensile and flexural behavior of hybrid epoxy composites with Carbon, Glass and Kevlar- 49 fibers were investigated. Tensile properties were obtained according to ASTM: D638–10 and flexural strength of the hybrid composites were obtained from the three point bending test according to ASTM: D790-10 at a span-to-depth ratio of 32. Hybrid composites were produced with different fiber weight fractions of Carbon/Glass, Carbon/Kevlar, Glass/Kevlar and Carbon/Glass/Kevlar. It is concluded that the hybridization phenomena is dependent on the strength ratios of Carbon/epoxy, Glass/epoxy and Kevlar/epoxy layers. The maximum change in tensile strength due to hybridization effect was achieved in Carbon/Glass epoxy laminate by replacing the two layers of a full Carbon/epoxy laminate with a Glass/epoxy, the strength decreased by 17.7%, and increased by 60% compared with those of the full Carbon and full Glass configurations, respectively. And also, the maximum change in flexural due to hybridization effect was achieved in Glass/Kevlar epoxy laminate by replacing the top two layers of a full Glass/epoxy laminate with a Kevlar/epoxy, the strength decreased by 26.5% and increased by 78% compared with those of the full Glass and full Kevlar configurations, respectively.