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Öğe Behaviour of bi adhesive in double strap joint with embedded to bending(Journal of Theoretical and Applied Mechanics, 2015-06-15) Adin, Hamit; Temiz, Şemsettin; Sülü, İsmail YasinIn this study, behaviour of bi-adhesive used in the repair of damaged parts was analyzed, using the finite element method. In a double-strap joint with an embedded patch, patch is embedded into the adherents for structural requirements. In addition, to increase the strength of the joint, two adhesives are used to bond the adherents. This approach reduces stress concentration at the overlap ends, increases the load capacity and delays the failure. These effects give rise to higher joint strength. For this purpose, a stiff adhesive, FM73 produced by Cytec Fiberite, was applied in the middle portion of the overlap, while a softer adhesive, SBT9244 from 3M, was applied towards the edges, prone to stress concentrations. Non-linear finite element analyses were carried out to predict the failure loads, to assist with the geometric design and to identify effective ratios of sizes to maximize joint strength. Key words: Bi-adhesive, double-strap joints, finite element analysis, mechanical properties, stress analysis, failure loadsÖğe Effect of welding parameters on microstructure and mechanical properties of AA7075/AA5182 alloys joined by TIG and MIG welding methods(SpringerLink, 2020) Çelik, Yahya Hışman; Temiz, Şemsettin; Çetkin, EdipIn this study, V and X welding grooves were opened to the forehead positions of the AA5182 and AA7075 aluminum alloy pairs and these alloy pairs were joined with tungsten inert gas (TIG) and metal inert gas (MIG) methods. Three diferent welding currents were used in joints. Gas fow rates of 12 and 17 l/min at the TIG welding and wire feed rates of 38 and 45 cm/min at MIG welding were selected. The efect of the welding grooves, welding current, gas fow rate and wire feed rate on microstructure and mechanical properties were investigated. Microstructures of welding zones were analyzed by an optical microscope and a scanning electron microscope (SEM). Vickers hardness of these zones was also measured. In addition, tensile and fatigue tests were carried out. Fracture mechanisms of failed specimens were conducted after the tensile tests were examined by using SEM. The highest hardness, tensile and fatigue strengths were obtained from the alloy pairs joined by opening X welding groove with TIG welding method. These values were 89 HV, 262.87 MPa, and 131.5 MPa, respectively. Similarly, the lowest tensile and fatigue strengths were obtained from the alloy pairs joined by opening V welding groove in the TIG welding method. These values were, respectively, 94.48 MPa and 19.1 MPa. However, the minimum hardness value was measured as 58 HV from the alloy pairs joined by opening V welding groove with MIG welding methods. In addition, it was observed on the fracture surfaces that the grain distributions and mechanisms difered depending on the welding methods, welding groove, and welding parameters.Öğe Experimental determination of the static and fatigue strength of theadhesive joints bonded by epoxy adhesive including different particles(Elsevier, 2018-12) Adin, Hamit; Saraç, İsmail; Temiz, ŞemsettinBecause of their many advantages, adhesively bonded joints are intensively used in many engineeringfields. So,the mechanical research of the adhesively bonded joints is very important to use these joints safely. There aremany studies performed by researchers to investigate the mechanical properties of the adhesive joints. There hasbeen a considerable interest in nanoparticles added to structural adhesives recently because nanoparticles im-prove the mechanical properties of adhesives and joints. In this paper, different nanoparticles reinforced byepoxy adhesive, and neat adhesive were used to produce single lap joints. The static and fatigue strengths ofsingle lap joints incorporating nanoparticles were compared to those without nanoparticles. Experiments wereperformed at 20 mm overlap length. DP460 epoxy was used as the adhesive material, and nano-Al2O3, nano-TiO2and nano-SiO2were used as the nanoparticles; and AISI 304 stainless steel plates were used as the adherents. Theresults of the experimental research revealed that average failure load increased significantly in nanoparticle-reinforced adhesive joints. The highest average failure load was obtained with 4 wt% nano-Al2O3in epoxyadhesive. Fatigue tests were performed at 10 Hz frequency, and 0.1 loading ratio (R). When the fatigue testresults were examined, it was observed that the addition of the nano-Al2O3and nano-SiO2to the adhesiveincreased fatigue strength of the adhesive joints, on the other hand, the addition of the nano-TiO2to the adhesivereduced fatigue strength of the adhesive joints.Öğe Experimental determination of the mechanical properties of adhesive joints bonded epoxy adhesive included Al2O3 nanoparticule(European Journal of Technic, 2016-08-01) Adin, Hamit; Saraç, İsmail; Temiz, ŞemsettinYapıştırma bağlantılarında, yapıştırıcı içerisine katılan nanopartiküllerin, bağlantıların mekanik özelliklerine etkisi ile ilgili araştırmalar son zamanlarda dikkat çekmektedir. Bu çalışmada; epoksi yapıştırıcı içerisine % 2 oranında Al2O3 nanopartikül katılarak ve katkısız epoksi yapıştırıcı kullanılarak tek tesirli bindirme bağlantıları oluşturulmuş ve bağlantıların mekanik özellikleri çekme yükü altında 20 mm, 25 mm ve 30 mm bindirme boylarında deneysel olarak incelenmiştir. Deneysel çalışmalarda DP460 epoksi yapıştırıcısı, Al2O3 nanopartikülleri ve yapıştırılan malzeme olarak St-37 çeliği kullanılmıştır. Deneylerden elde edilen sonuçlar incelendiğinde; % 2 Al2O3 nanopartikül katkılı yapıştırıcıların kullanılmasıyla 20 mm ve 30 mm bindirme boylu bağlantılarda genel olarak hasar yükü azalmıştır. Ancak 25 mm bindirme boyunda % 5 oranında bir artış görülmüştür. Ayrıca nanopartikül ilavesi bağlantıların uzama kapasitelerine azaltıcı yönde etki yapmıştır.Öğe Repair of an aluminum plate with an elliptical hole using a composite patch(Carl Hanser Verlag, 2018-11-15) Ergün, Raşit Koray; Adin, Hamit; Şişman, Abdullah; Temiz, ŞemsettinIn this paper, the stress on axially loaded metal sheets with elliptical holes reinforced by a double-sided composite patch was analysed. The metal sheets with elliptical holes were subjected to axial loading, although no load was applied along the edges of the holes. The central elliptical holes on the metal plates had different diameters. The overlap distance of composite patches, which were adhesively bonded on each side, was of varied lengths. Elasto-plastic stress analyses were examined by means of the finite element method (FEM). The experimental results were compared with numerical results and a convergence rate of 92 % was achieved.Öğe Microstructure and mechanical properties of AA7075/AA5182 jointed by FSW(Journals & Books, 2019-06) Çelik, Yahya Hışman; Çetkin, Edip; Temiz, ŞemsettinIn this study, AA7075 and AA5182 aluminium alloys were joined using different rotation speeds (980, 1325 and 1800 rpm), feed rates (108 and 233 mm/min) and stirred pins having two different geometries (conical helical and triangular). Microstructures of welding joints were examined by an optical microscope and a scanning electron microscope (SEM). Vickers hardness measurements were performed in the welding zone of samples removed from each welded plate. Tensile and fatigue tests were also applied to the test specimens taken from the welded plates. After the tensile tests, the surface fractures and possible welding defects were scanned via SEM. The best mechanical properties were obtained when conical helical shape stirrer pins were used. The values were 265 MPa for tensile test and 159 MPa for fatigue test. The hardness value was very close to each other and varied depending on the rotation speed. The highest hardness value was determined as 87 HV in the weld center at 1325-rpm rotation speed.Öğe Experimental and numerical strength analysis of double lap joints subjected to tensile loads(Materials Testing, 2014) Adin, Hamit; Temiz, ŞemsettinIn this paper the mechanical behaviour of double lap joints (DLJs) bonded with adhesive was analyzed. The stress-strain behaviour was investigated along the overlap length and adherend thickness in DLJs subjected to tensile loads. The stress analyses were performed by finite element method (FEM). The FEM calculations were performed using ANSYS (12.0.1). Experimental results were compared with the FEM results and were found to be quite reasonable. The results show that the failure loads are increased with an increase in adherend thickness. The stress-strain behaviour changes depending on adherend thickness and overlap length. Both FEM stress analyses and experimental results revealed that failure occurred around the edge zones of the overlap length due to the effect of shear stresses, while the failure at the edges of the adhesive layer originated from the peel stress in tensile.Öğe Microstructure and mechanical properties of AA7075/AA5182 jointed byFSW(Elsevier, 2019-06) Çetkin, Edip; Çelik, Yahya Hışman; Temiz, ŞemsettinIn this study, AA7075 and AA5182 aluminium alloys were joined using different rotation speeds (980, 1325 and 1800 rpm), feed rates (108 and 233 mm/min) and stirred pins having two different geometries (conical helical and triangular). Microstructures of welding joints were examined by an optical microscope and a scanning electron microscope (SEM). Vickers hardness measurements were performed in the welding zone of samples removed from each welded plate. Tensile and fatigue tests were also applied to the test specimens taken from the welded plates. After the tensile tests, the surface fractures and possible welding defects were scanned via SEM. The best mechanical properties were obtained when conical helical shape stirrer pins were used. The values were 265 MPa for tensile test and 159 MPa for fatigue test. The hardness value was very close to each other and varied depending on the rotation speed. The highest hardness value was determined as 87 HV in the weld center at 1325-rpm rotation speed.
