Person: ÇAKIR, MUSTAFA CEMAL
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ÇAKIR
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MUSTAFA CEMAL
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Publication Experimental and numerical investigation of in-plane and out-of-plane impact behaviour of auxetic honeycomb boxes produced by material extrusion(Gazi Üniversitesi, 2021-02-21) Çakan, Betül Gülçimen; Ensarioğlu, Cihat; Küçükakarsu, Volkan M.; Tekin, İbrahim E.; Çakır, M. Cemal; GÜLÇİMEN ÇAKAN, BETÜL; ENSARİOĞLU, CİHAT; Küçükakarsu, Volkan M.; Tekin, İbrahim E.; ÇAKIR, MUSTAFA CEMAL; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0003-4118-8639; 0000-0003-1739-1143; F-9772-2018; AFD-6959-2022; DAO-6186-2022; HQW-4065-2023; JIT-5147-2023Auxetic structures, which have a negative Poisson's ratio, have good mechanical energy/impact absorption properties. These structures have found application in sandwich composites in the aerospace and defence industries, in the production of armour or protective sports equipment. In this study, the mechanical behaviour of the auxetic honeycomb structure in different directions (in-plane and out-of-plane) under impact loading was investigated. For the in-plane (x and y) and out-of-plane (z) directions, boxes with an auxetic honeycomb structure were produced by material extrusion method using Power ABS filament. In the experimental study, dynamic tests were carried out with a drop test machine. Besides, explicit analyses were performed by creating finite element models for these 3 directions. The experimental and numerical results have shown that the energy absorption property of auxetic honeycomb geometry is superior in the case of out-of-plane loading, in agreement with each other. In in-plane loadings, crush force efficiency (CFE) and crush forces were lower.Publication Process optimisation of hmdso polymerisation in pvd vacuum medium by numerical analysis for automotive industry(Gazi Üniversitesi, 2021-01-01) Geçim, Serkan; Kıdık, Gökmen; ; Sözer, İbrahim Emrah; Çakır, Mustafa Cemal; ÇAKIR, MUSTAFA CEMAL; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; 0000-0002-8774-7048A protective film layer is formed over aluminum coating with Physical Vapor Deposition (PVD) processes to ensure the resistance to environmental factors of the sub-components that include headlight reflective surfaces. Increasing endurance of the sub-components to environmantol factors is demanded with the development of automotive quality demands. In this study, Hexamethyldisiloxane (HMDSO) monomer releasing system that is used to form a protective film layer in PVD processes, has been optimized for releasing homogenously through the pipeline to the vacuum chamber by using finite volumes method. In addition, for uniform distribution of the HMDSO monomer release before polymerization into the vacuum medium, the substrate's jig revolution mechanics were analyzed by Computational Fluid Dynamics (CFD) simulations and the results were verified by experimental applications. The Sodium Hydroxide (NaOH) resistance of parts in various regions of the vacuum chamber was between 350-550 seconds before the study. However, it has been carried to over 1000 seconds for all regions after the optimisation process. Thus, ultimate life of the part and parts' resistance to environmental factors are increased. Thanks to this study, the desired quality requirement for the sub-components that are coated in the vacuum chamber with a volume of 2,84 m(3) was provided for all parts in different regions within the chamber. There is no need for new single planet machines with 1,13 m(3) volume vacuum chamber and production output that was obtained with the bigger chamber machine is doubled. No similar works have been found that are carried out by suppliers or in the literature.Publication Investigating the benefits of using circular die springs instead of rectangular die springs(Wiley, 2015-07-01) Gönen, D.; Oral, A.; Çakır, Mustafa Cemal; ÇAKIR, MUSTAFA CEMAL; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü; HOR-0562-2023Die springs with rectangular cross section (rectangular die springs) are common in the industry. However, the production of rectangular die springs is difficult, and the cost of production is high. In this study, we examined the use of die springs with circular cross section (circular die springs), which are both easier to produce and less costly, in place of rectangular ones. To this aim, the fatigue life values of both die spring with equivalent specifications were compared experimentally. The results obtained were transferred to the finite element methods software to run the simulation of the fatigue test. From the experimental results obtained, it has been observed that using circular die springs in place of rectangular die springs is always possible, provided that the springs are guided with cast polyamide guides.Publication Influence of cutting parameters on the chip-tool interface temperature during the turning of Waspaloy(Carl Hanser Verlag, 2015-09-01) Işık, Yahya; Kuş, Abdil; Çakır, Mustafa Cemal; IŞIK, YAHYA; KUŞ, ABDİL; ÇAKIR, MUSTAFA CEMAL; Uludağ Üniversitesi/Teknik Bilimler Meslek Yüksekokulu; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü; AAG-9412-2021; FBP-1850-2022; HOR-0562-2023Waspaloy, as a nickel superalloy, is a difficult-to-machine material used for gas turbine engine components that require considerable strength and corrosion resistance at high operating temperatures. The machining of nickel-based alloys generates high temperatures at the cutting tool edge. This research investigated the relationship between cutting parameters and cutting temperature, using a remote temperature measurement method employing an infrared thermometer. In addition, the effects of cutting parameters on surface roughness were examined. Experiments were conducted on Waspaloy AMS5708 superalloy samples and a PVD TiAlN-TiN-coated WNVG 080404-IC907 carbide insert was used during the turning process. It was observed that the highest cutting speed and highest feed rate generated higher temperatures and higher surface roughness. Better surface roughness was obtained with the lowest feed rate, the highest cutting speed and the higher cutting depth. No cutting fluid was used in the experiments.Publication Wear and residual stress in high-feed milling of aisi h13 tool steel(Walter De Gruyter Gmbh, 2023-09-28) Koca, Selim; Bakırcı, Altuğ; Erdoğan, Özlem; Çakır, Mustafa Cemal; ÇAKIR, MUSTAFA CEMAL; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; HMV-8715-2023With the new manufacturing technologies, it has been possible to machine hard metals efficiently. During high-speed machining (HSM) of high-strength steel, the poor surface integrity of the workpiece affects the performance of the process. Surface roughness, microstructure, micro hardness and residual stress are key performance indices for surface integrity directly controlled by tool wear and cutting parameters. In this study, high-feed milling (HFM) of a pocket on test samples made of DIN 1.2344 ESR mould steel with 55 HRc hardness was carried out on the CNC vertical milling machine. Three different cutting speeds and five different feed rates were used. At the end of the machining, tool wear was measured using a microscope. Subsequently, X-ray diffraction and hole drilling procedures were used to quantify residual stresses on machined test specimens. The results showed that under cutting conditions, the highest tensile residual stress was attained at f(z )= 0.78 mmtooth(-1), v = 127.58 mmin(-1), and the highest compressive residual stress at f(z) = 0.5 mmtooth(-1), v = 127.58 mmin(-1), on the workpiece surface. The most suitable cutting parameters were reported as f(z) = 0.63 mmtooth(-1) and v = 70 mmin(-1) cutting speed when tool wear and residual stresses are considered together.Publication Investigation of the effect and optimization of material properties on the printed circuit board(Sage Publications Ltd, 2023-10-01) Berk, Bilbay Fahri; Erhan, Arslan; Baris, Ediz; Çakır, Mustafa Cemal; ÇAKIR, MUSTAFA CEMAL; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.Printed circuit boards (PCBs) have a sandwich structure consisting of an insulating composite layer between conductive copper layers. The material property of the PCB cannot be defined as isotropic due to this special structure. In addition, variables such as the types of hundreds of components on the PCB, material properties, types of solder leads, and thickness of the sandwich structure make it very difficult to create and verify the finite element model of the PCB. The aim of this study is to perform a sensitivity analysis by defining the strain values measured from three points on the PCB with the help of strain gauges as responses and to find the best design variables that correlate with the physical test. The effect of each design parameter on the response function was examined, and the results were obtained with statistical data. The objective function and constraints were determined to find the best correlated finite element model with a physical test, and the best design was obtained by running the optimization model. In this way, the finite element model was calibrated by taking into account the thermal stresses resulting from the heat generated by the transistors and by using optimization methods.Publication Improving the load distribution in the automobile front collision zone by adding 's' shaped curved collision rail(Pamukkale Univ, 2023-01-01) Bilbay, Fahri Berk; REİS, MURAT; Bilbay, Fahri Berk; Reis, Murat; Gülçimen Çakan, Betül; Ensarıoğlu, Cihat; ENSARİOĞLU, CİHAT; Çakır, Mustafa Cemal; ÇAKIR, MUSTAFA CEMAL; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/ Makine Mühendisliği Bölümü.; F-9772-2018In this study, the performance of the front collision zone of the vehicle, reinforced with an S-shaped front collision rail, was compared to that of the classic straight front collision rail. In order to create a safe living cage in automobiles, half vehicle model was used and the collision performances of two different front collision zone models were compared. Torsion, bending and frontal impact scenarios were created with Hyperworks-Optistruct software to obtain versatile and continuous load paths in the vehicle. Vehicle front collision zone elements were designed with Siemens NX software based on the resulting load paths. Altair Hypermesh software was used to create the material properties, connection/contact zones and element mesh structures of the front collision zone components, and thus the preprocessing step was completed. Two different collision zone models were used to compare the collision zone with the classic arm and the one reinforced with the "S" shaped collision arm. The amount of energy absorbed by the collision zone components, the total displacement in the collision zone, the loads transmitted to the passenger cabin and the efficiency of the collision force (CFE) were obtained from each simulation.Publication Innovative low-cost, cold-walled CVD process development and CNT production by ethanol decomposition on iron-nanoparticles(Taylor & Francis Ltd, 2022-08-31) Cilsal, O. Ozan; Çakır, M. Cemal; Uğuz, Agah; Cilsal, O. Ozan; ÇAKIR, MUSTAFA CEMAL; UĞUZ, AGAH; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0002-5736-8557; CKX-4912-2022; HOR-0562-2023; EBY-1783-2022A novel cold-walled CVD reactor has been designed for low-cost CNT synthesis. Aim was to eliminate the need for electric furnace, carbon-containing gas tanks and flowmeters, reducing energy consumption and gas emissions. Iron nanoparticles emulsion dip coating was preferred to simplify the catalyst preparation process. As carbon precursor, ethanol is used. Cost analysis was made to determine the initial investment needed. Design is also patented against unauthorized commercial usage. Samples obtained were characterized using SEM and Raman spectroscopy. Multi-walled CNTs and CNFs with diameters from 50nm to700 nm in straight and helical form have been synthesized. It has been observed that increase of the process duration and remaining soot on the reactor components has a diameter reducing and yield increasing effect on CNTs. Raman spectroscopy results show D, G and 2D Bands on the samples.