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Öğe Effect of particle shape on the wear and friction behavior of particle-reinforced epoxy coatings(Springer, 2019) Çınar, Kenan; Eruslu, Sait Özmen; Dalmış, İbrahim Savaş; Güven, İbrahimEpoxy coatings are increasingly becoming popular choices as barriers against acids and alkali for protection of concrete and metal products. In applications, metal containers are often coated with epoxy-based coatings to prevent rusting and corrosion. In this study, an experimental examination was carried out to investigate the effect of particle shape and size on the friction and wear behavior of epoxy coatings. Friction and wear experiments were conducted using a pin-on-disk tribometer. Epoxy resin was filled with four different shapes of glass particles (spherical, flake, rod, and irregular shape) and varying particle sizes. Fillers were settled down and filler surface area fraction through thickness was characterized using microcomputed tomography (micro-CT). The wear mechanisms such as matrix wear, matrix cracking, particle fracture, particle debonding, and pullout and debris formation were studied using scanning electron microscopy. According to observations, it was found that particle shape has an effect on the wear characteristic. Particle fracture and particle pullout mainly dominated the wear in the samples of flake- and rod-shaped fillers, perpendicular matrix cracks occurred in the samples of spherical fillers, large debonding at the particle-matrix interface without particle pullout occurred in the samples of large irregular-shaped fillers (75-150 mu m), and matrix cracks dominated the wear as the size of irregular-shaped fillers decreased to 50-75 mu m. Further, it was found that friction coefficient depends on the shape of the particle. The samples with spherical- and irregular-shaped fillers had higher friction coefficient as compared to the samples with flake and rod fillers.Öğe Fatigue Life Enhancement of Three Point Hitch System Brackets in the Garden Series Tractors(Ankara Univ, Fac Agr, 2017) Dalmış, İbrahim Savaş; Tezcan, Olcay; Eruslu, Sait ÖzmenThe main objective of this research was to enhance the fatigue performance of the brackets found in the three point hitch system used in garden series tractors. This was achieved by using experimental tests and finite element analysis. The manufactured brackets were validated with fatigue rig tests, namely a lifting capacity test, a push-pull test and a lifting lowering test. The lifting capacity test of three point hitch mechanism was established according to ISO 730-1 standards. In addition to the lift capacity test, problems were also experienced with the cylinder clamping brackets during the pushpull tests. The bracket brakeage occurred during the 11,218th test cycle. According to the test results and finite element analysis, the brackets were strengthened at critical damage points. The thickness of the bracket connection surface was increased from 12 mm to 19 mm and the bracket material was changed from GG25 to GG35. The enhanced brackets passed the tests without any breakage.Öğe Finite element modeling of glass particle reinforced epoxy composites under uniaxial compression and sliding wear(Walter De Gruyter Gmbh, 2021) Eruslu, Sait ÖzmenIn this study, the failure mechanism of glass particle epoxy composites was investigated under compression and sliding wear. Random fiber distribution with minimum interfiber distance was modeled by representative volume elements (RVEs). Spherical and platelet type glass particles were used for the reinforcements. A numerical simulation of the elastic properties of composites was performed for a perfectly bonded interface, and the results were compared using the Mori Tanaka mean field approach. The elastic stiffness results indicated that the platelet reinforced composites bore more load than spherical ones because of the aspect ratio effects. The separation distance based cohesive zone model was applied to modeling the failure zone at the particle matrix interfaces to establish sliding wear. The effect of the perfectly bonded interface and the cohesive zone interface on overall stiffness and elasto-plastic behavior were discussed. The cohesive zone interface was found to be effective at the interface in terms of the strength and debonding characteristics of the composites. The results were compared with the sliding wear test results of glass particle reinforced composites. The numerical and sliding wear experimental results indicated that matrix yield stress, plastic strain, particle penetration at the contact interface and particle stress are found to be effective parameters for the debonding mechanism.Öğe Finite element modelling of crackable connecting rods at fracture splitting process(Kaunas Univ Technol, 2015) Özdemir, Tekin; Eruslu, Sait ÖzmenIn this study crack propagation analysis of impulsively loaded connecting rods with different microstuctures namely perlitic, bainitic, tempered martensitic were studied numerically for evaluation of fracture parameters. Fracture splitting parameters in experiments for uniform impact force distribution was concerned in numerical analysis. Brittle crack propagation at starting notchs was obtained by impulsive load. Dynamic crack propagation was studied by using two dimensional finite element model and crack tip positions were determined by remeshing algoritm. Dynamic stress intensity factors were calculated by J integral technique and celevage failure was detected according to dynamic fracture toughness parameters by instrumented Charpy impact test. Crack propagation, crack arrest times, cleavege times were found and compared numerically for three different microstructures. Predicted shear effective stress intensity calculations, crack tip velocity, crack extesion results are found supplementary data for experimental fracture parameter optimisation.Öğe Free vibration analysis of short fiber reinforced laminated plates with first shear deformation theory(2012) Eruslu, Sait Özmen; Aydo?du, MetinVibration analysis of simply supported square laminated plates containing randomly and unidirectionally aligned short fibers was performed. The effective elastic modulus of composite was expressed by using the Mori-Tanaka mean field approach. The results were compared with the rule of mixture and Hashin bounds. The governing equations were obtained by means of Hamilton's principle and solved by using the Navier type solution and Ritz method. The effects of the fiber orientation, the degree of orthotropy, the fiber aspect ratio, the plate span to thickness ratio, and the fiber volume fraction on the vibration behavior of the laminated plates were studied. The mode frequency results are compared with results of the finite element model. It is observed that for increasing degree of orthotropy, the difference between the frequency parameters increases for increasing aspect ratio. The mode frequency results show that for larger aspect ratios, the frequencies for short fibers approach those of continuous fibers. © TÜBİTAK.Öğe Hydroforming analysis of exhaust pipe connectors(Carl Hanser Verlag, 2020) Marangoz, Riza; Eruslu, Sait Özmen; Dalmış, İbrahim SavaşIn this work, a hydroforming analysis of an exhaust pipe clamp adaptor made of galvalume steel was performed. Deformation and failure of galvalume exhaust pipe connectors and its coatings via the hydroforming process were studied. An explicit type (LsDyna) numerical analysis approach was adapted for the development of the hydroforming process. Pressure rate, unconstraint length, residual stress, strain hardening, and spring-back effects were considered in the analysis. The failure of tubular parts was evaluated via a forming limit diagram (FLD) according to Hill- Swift criteria. The hydroforming process was developed according to three models, which are found in the safety forming region of FLD studies. Minimum thickness values obtained from the experiments were compared with finite element analysis (FEM). The maximum percentage thinning ratio in the tubular section was more than 18 - % at 65 MPa internal pressure. The relationship between thickness reduction at plastically work hardening regions and residual stress was discussed. The deformation characteristics of the produced connector headers were also analyzed by scanning electron microscopy (SEM) and micro Vickers hardening measurements. The FEM analysis and FLD examination indicated that the failure did not occur in hydroformed specimens, whereas damage was observed at coated' plastic work regions through microscopical investigation.Öğe İNCE CİDARLI BASINÇLI TÜPLERİN SONLU ELEMANLAR YÖNTEMİYLE ANALİZİ(Pamukkale Univ, 2008) Eruslu, Sait ÖzmenBu çalısmada ince cidarlı basınçlı tüplerde ASTM standartlarında belirtilen iki farklı çelik için basınç etkisi altında gerilme analizi yapılmıstır. ki boyutlu ve üç boyutlu sonlu elemanlar modelleri Ansys 9.0 yardımıyla olusturulmus, üç boyutlu model tasarım yönünden iki farklı sekilde incelenmistir. Maksimum gerilme kriteri yardımıyla patlama basınçları bulunmus, tüp üzerindeki hasarlı bölgeler belirlenmistir. Hasar sonuçları Von Mises kriteri sonuçları ve standartlardan elde edilen analitik sonuçları ile karsılastırılmıstır. nce cidarlı basınçlı tüplerin sonlu elemanlar analizinde olusturulan modelin, tasarımsal etkilerin etkinligi ortaya çıkmıstır. Analize dayalı patlama basıncı sonuçları standartlardan elde edilen analitik sonuçlara göre daha yüksek bulunmustur.Öğe İnce cidarlı basınçlı tüplerin sonlu elemanlar yöntemiyle analizi(2008) Eruslu, Sait ÖzmenBu çalışmada ince cidarlı basınçlı tüplerde ASTM standartlarında belirtilen iki farklı çelik için basınç etkisi altında gerilme analizi yapılmıştır. ki boyutlu ve üç boyutlu sonlu elemanlar modelleri Ansys 9.0 yardımıyla oluşturulmuş, üç boyutlu model tasarım yönünden iki farklı şekilde incelenmiştir. Maksimum gerilme kriteri yardımıyla patlama basınçları bulunmuş, tüp üzerindeki hasarlı bölgeler belirlenmiştir. Hasar sonuçları Von Mises kriteri sonuçları ve standartlardan elde edilen analitik sonuçları ile karşılaştırılmıştır. nce cidarlı basınçlı tüplerin sonlu elemanlar analizinde oluşturulan modelin, tasarımsal etkilerin etkinliği ortaya çıkmıştır. Analize dayalı patlama basıncı sonuçları standartlardan elde edilen analitik sonuçlara göre daha yüksek bulunmuştur.Öğe Mechanical analysis of al/foam composite sandwich panels under elastic and elastoplastic states(2024) Eruslu, Sait ÖzmenThis study performs mechanical analysis for Al/Foam composite sandwich panels under 3-point bending using numerically and experimentally. The flexural rigidity, elastic deflections, and normal, shear stresses are obtained by analytical calculations of the Timoshenko beam equation and compared finite element (FE) models for 3-point bending loading conditions. The FE models are constructed using 2D single-layer shell and 3D solid discrete-layer models. The validity of FE models at the analysis is evaluated for Al/PVC Foam sandwich composites for the elastic state. The experimental bending results of Al/XPS Foam sandwich composites are compared with numerical models at elastic and elastoplastic states. The elastic results indicate that the out-of-plane deflection results agree well across numerical and analytical models. Normal stresses at the core are higher in 3D discrete-layer solid models compared to laminated shell theory-based models for thick plates, due to the more accurate characteristics of the discrete-layer solid models. The Timoshenko beam theory-based analytical bending results show a good correlation with the results from laminated shell theory-based finite element method (FEM) analyses. Elastoplastic FEM analysis indicates that discrete-layer-based 3D solid FEM models effectively predict local effects dependent on indentation failure.Öğe Modeling of Buckling Restrained Braces (BRBs) using Full-Scale Experimental Data(Korean Society Of Civil Engineers-Ksce, 2019) Avci-Karataş, Çiğdem; Çelik, Oguz C.; Eruslu, Sait ÖzmenHysteretic performance of buckling restrained braces (BRBs) having various core materials, namely, steel and aluminum alloy and with various end connections are numerically investigated. As a computational tool, nonlinear finite element analyses (FEAs) are performed to better model the hysteretic behavior. For the simulation, various aspects such as 1) stress - strain relationship including the strain hardening effect 2) von Mises yield criterion 3) contact surface parameters between the core metal and surrounding high strength grout and 4) friction are defined. Experimental results from near-full scale cyclic tests on two steel core BRBs having steel casing as a restraining environment (named as BRB-SC4 and BRB-SC5) and an aluminum alloy core & aluminum alloy casing tube (named as BRB-AC3) are used in the analyses. All cyclically tested specimens have been designed according to AISC Seismic Provisions. Numerical results obtained from 3D models developed in ANSYS-Workbench give satisfactory response parameters when compared with the experimental ones (e.g., hysteretic curves, dissipated energies). Further, a convergence analysis regarding element numbers in the developed model is conducted for each BRB specimen. Finally, key issues that influence the hysteretic modeling of BRBs are identified.Öğe Vibration Analysis of Inclusion Reinforced Composite Square Plates under Various Boundary Conditions(Sage Publications Ltd, 2009) Eruslu, Sait Özmen; Aydoğdu, MetinThe vibration behavior of E-glass epoxy cross-ply laminated plates containing unidirectionally aligned inclusions was studied under different boundary conditions by using first-order shear deformation theory (FSDT). The effective elastic modulus of composite was expressed by using the Mori-Tanaka mean field approach for unidirectionally aligned inclusions. The governing equations were obtained by means of the Hamilton's principle and solved by using the Navier-type solution and Ritz method. The continuity of transverse shear stress between layers of the symmetric cross-ply laminated plates was satisfied by the use of the shape function incorporated into the theory. The effects of the inclusion volume fraction, the inclusion aspect ratio, and the plate span to thickness ratio on the vibration behavior of the laminated plates were studied. It was found that the dimensionless frequency increases with increasing the aspect ratio of the reinforcements and approaches asymptotically to frequency of the continuous fibers.
