Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
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Book Part Citation - WoS: 1Citation - Scopus: 1A Historical Review of Polyhedral Linkages(Springer, 2024) Kiper, GökhanPolyhedral linkages are linkages that resemble polyhedral shapes at different configurations. This paper summarizes the necessary geometrical fundamentals of polyhedral geometry and presents a historical and critical review of the polyhedral linkage designs available in the literature. Basic definitions of polyhedral geometry and operations are needed to comprehend and design polyhedral linkages. First, early works on polyhedral linkages are presented, where flexible polyhedra with rigid faces and flexible edges are issued. The final part is reserved to conformal polyhedral linkages, which go through shape transformations while plane, dihedral and solid angles are preserved. Conformal polyhedral linkages are examined in four categories: 1) Jitterbug-like linkages with screwing polygonal links connected to each other with dihedral angle preserving links, 2) polyhedral linkages with planar kinematic chains in radial motion planes, 3) polyhedral linkages with planar kinematic chains on faces, that are connected to each other with dihedral angle preserving links, and 4) other conformal polyhedral linkages. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.Article Citation - WoS: 2Citation - Scopus: 3Design and Manufacturing of a Hip Joint Motion Simulator With a Novel Modular Design Approach(Springer, 2024) Torabnia, S.; Mihçin, D.Ş.; Lazoglu, I.The study is aimed to develop a hip joint wear simulator using a modular design approach to help experimentally monitor and control critical wear parameters to validate in-silico wear models. The proper control and application of wear parameters such as the range of motion, and the applied force values while estimating the lost material due to wear are essential for thorough analysis of wear phenomena for artificial joints. The simulator's dynamics were first modeled, then dynamic loading data was used to calculate the forces, which were further used for topology optimization to reduce the forces acting on each joint. The reduction of the link weights, connected to the actuators, intends to improve the quality of motion transferred to the femoral head. The modular design approach enables topology-optimized geometry, associated gravitational and dynamic forces, resulting in a cost-effective, energy-efficient product. Moreover, this design allows integration of the subject specific data by allowing different boundary conditions following the requirements of industry 5.0. Overall, the in-vitro motion stimulations of the hip-joint prosthesis and the modular design approach used in the study might help improve the accuracy and the effectiveness of wear simulations, which could lead into the development of better and longer-lasting joint prostheses for all. The subject-specific and society-based daily life data implemented as boundary conditions enable inclusion of the personalized effects. Next, with the results of the simulator, CEN Workshop Agreement (CWA) application is intended to cover the personalized effects for previously excluded populations, providing solution to inclusive design for all. © 2023, The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.Article Citation - WoS: 9Citation - Scopus: 11Experimental Investigation of Spray Characteristics of Ethyl Esters in a Constant Volume Chamber(Springer, 2024) Ulu, A.; Yildiz, G.; Özkol, Ü.; Rodriguez, A.D.Abstract: Biodiesels are mainly produced via the utilization of methanol in transesterification, which is the widespread biodiesel production process. The majority of this methanol is currently obtained from fossil resources, i.e. coal and natural gas. However, in contrast with methanol, biomass-based ethanol can also be used to produce biodiesels; this could allow the production line to become fully renewable. This study aimed to investigate the spray characteristics of various ethyl ester type biodiesels derived from sunflower and corn oils in comparison to methyl esters based on the same feedstocks and reference petroleum-based diesel. Spray penetration length (SPL) and spray cone angle (SCA) were experimentally evaluated in a constant volume chamber allowing optical access, under chamber pressures of 0, 5, 10 and 15 bar and injection pressures of 600 and 800 bar. Sauter mean diameter (SMD) values were estimated by using an analytical correlation. Consequently, ethyl esters performed longer SPL (2.8–20%) and narrower SCA (5.1–19%) than diesel under ambient pressures of 5 and 10 bar. Although the SMD values of ethyl esters were 48% higher than diesel on average, their macroscopic spray characteristics were very similar to those of diesel under 15 bar chamber pressure. Moreover, ethyl esters were found to be very similar to methyl esters in terms of spray characteristics. The differences in SPL, SCA and SMD values for both types of biodiesels were lower than 4%. When considering the uncertainty (± 0.84%) and repeatability (±5%) ratios, the difference between the spray characteristics of methyl and ethyl esters was not major. Graphical abstract: [Figure not available: see fulltext.] © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Conference Object Energy and Exergy Analysis of a Roof-Mounted Photovoltaic System in Gebze-Turkey(Springer, 2024) Khalejan, Seyed Hamed Pour Rahmati; Cankurt, Tolga; Dede, Mehmet İsmet CanThis study investigates the electrical and thermal exergy, power conversion efficiency and exergy efficiency of a roof-mounted photovoltaic (PV) system considering environmental parameters such as solar irradiation, ambient temperature and wind speed over a year. The values of solar exergy and solar potential are obtained by taking into account the solar insolation. Experimental and theoretical results indicate that wind speed and surface temperature have significant effects on the thermal exergy and exergy efficiency of solar PV systems. The mean solar potential in the region was found to be 93%. In addition, the electrical exergy was varied from 9145 W to 40460 W and the thermal exergy of PV systems was varied from 1639 W to 6193 W. While the range of PV power conversion efficiency varies from 6.15% to 11.56% over a year, the range of exergy efficiency varies from 5.31% to 9.78%. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.Article Citation - WoS: 2Citation - Scopus: 4A Study on a Computationally Efficient Controller Design for a Surgical Robotic System(Springer, 2023) Ayit, Orhan; Dede, Mehmet İsmet CanThe control algorithms of the surgical robotic system using the robot’s dynamics produce a relatively high computational load on the processor. This paper develops a computationally efficient computed torque controller by using a simplified dynamic modeling method and implemented in a novel surgical robot experimentally. In addition, an independent joint controller is designed and implemented to compare the results of the computed torque controller. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Article Citation - WoS: 3Citation - Scopus: 5Single- and Multiobjective Optimizations of Dimensionally Stable Composites Using Genetic Algorithms(Springer, 2021) Aydın, Levent; Artem, Hatice Seçil; Deveci, Hamza ArdaThe present study aims to design stacking sequences of dimensionally stable symmetric balanced laminated carbon/epoxy composites, with different numbers of layers, with a low coefficient of thermal expansion and high elastic moduli. To avoid excessive interlaminar stresses in the composites, the contiguity constraint for plies is also taken into consideration. In the design process, both single- and multiobjective optimization approaches, including genetic algorithms, are utilized. Results showed that stacking sequences ensuring lower thermal expansion coefficients and higher elastic moduli than those of traditional laminate designs can be obtained.Conference Object Citation - Scopus: 26Optimization of Hip Implant Designs Based on Its Mechanical Behaviour(Springer, 2022) Göktaş, Hasan; Subaşı, Eda; Uzkut, Metin; Kara, Mustafa; Biçici, Hamit; Shirazi, Hadi; Mihçin, ŞenayTotal Hip Arthroplasty (THA) is one of the best advancements in healthcare. THA is required when the hip joint causes immobility and pain. The designed hip implants vary in geometry with different geometrical parameters. The geometry plays an important role in the mechanical behavior of the hip implant. In this study, the optimum selection of hip implant under static loading was evaluated using Finite Element Modeling (FEM). Hip implants with three different stem cross-sections including. (a) elliptic, (b) oval, and (c) trapezoidal were designed using a commercial Computer-Aided Design (CAD) software package. The FEM analysis was carried out via ANSYS R2019 to assess the key mechanical parameters of the implants such as stress distribution and deformation. The results were evaluated for the best stress and strain values. The optimum design had equivalent stress (von Misses) of 258,1 MPa, equivalent strain of 0.004, with total deformation of 0.24 mm and frictional stress of 0.362 MPa producing best values for trapezoidal cross-sectioned design. The findings of this study provided an insight into the selection of appropriate hip implant design with certain geometric design parameters to produce optimum results in clinical applications. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.Conference Object Citation - Scopus: 14Mechanical Investigation for the Use of Polylactic Acid in Total Hip Arthroplasty Using Fem Analysis(Springer, 2022) Çelik, Emre; Alemdar, Furkan; Batı, Murat; Daşdemir, Muhammed Furkan; Büyükbayraktar, Onur Alp; Chethan, K.N.; Mihçin, ŞenayPolylactic acid (PLA) is a biodegradable non-toxic, biocompatible polymer used as a popular filament material in biomedical applications with the advance of 3D printing technologies. PLA is considered a suitable implant material due to its contribution to bone regeneration. In this study, the use of PLA in Total Hip Arthroplasty (THA) as a liner material was assessed. In this regard, the PLA liner with different material combinations in THA was examined to provide evidence for its potential. The hip implant prototypewas drawn using a computer-aided design tool then transferred into a commercial finite element analysis (FEA) software. The prototypesconsisted of assemblies of PLA with titanium, chrome cobalt, stainless steels, dense NiTi shape-alloys, and Alumina-Zirconia. Simulations were run under static loading conditions. To evaluate and compare the results for the optimum design; factor of safety, total deformation and von Mises stress analysis were used. The results show that Co-Cr implemented implants produce the highest factor of safety. When Al-Zi combined with PLA, it produced least deformation and reasonable von- Mises stress values. PLA might perform best when used with Al-Zi. As a next step, experimental pre-clinical tests are planned to assess the clinical potential. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.Book Part An Experimental Setup and Procedure for Stiffness Evaluation of Robot Manipulators(Springer, 2021) Görgülü, İbrahimcan; Paksoy, Erkan; Carbone, Giuseppe; Dede, Mehmet İsmet CanIn this paper, an experimental test setup for stiffness evaluation of a spatial parallel mechanism is introduced. The parallel mechanism used in this study is R-CUBE mechanism. In the test setup, a highly rigid gantry-type manipulator’s end-effector is coupled with the R-CUBE’s mobile platform. As the gantry manipulator is actuated the resultant reaction forces/moments are measured via a force\torque sensor. Subsequently, compliant displacements of R-CUBE are measured by using a coordinate measuring machine. The obtained results are presented and discussed in this paper. © 2021, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG.Book Part Citation - Scopus: 2Computation Time Efficient Stiffness Analysis of the Modified R-Cube Mechanism(Springer, 2019) Görgülü, İbrahimcan; Dede, Mehmet İsmet CanParallel manipulators are known to be more stiff than the serial manipulators. However, modeling the stiffness for parallel manipulators are difficult compared to serial manipulators due to the constrained structure and passive joints. In addition, computation of the stiffness model for parallel manipulators are exhausting since it requires an iterative solution algorithm due requirement of force-position convergence of all serial chains connecting to the same mobile platform. Direct solutions are faster however, they lack in accuracy. In this study, direct solution is preferred for real-time application and analytic stiffness model of the modified R-CUBE mechanism is obtained by using Virtual Joint Method (VJM). The finite element (FE) model is constructed and simulated to validate the analytical model. Then, a combination of external wrenches $$\pm 5$$ N in various directions are applied on the mobile platform in both FE and VJM in some critical poses. Finally, the computed numerical results are listed and compared along with their computation times. © Springer Nature Switzerland AG 2019