Researcher:
Oral, Atacan

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PhD Student

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Atacan

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Oral

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Oral, Atacan

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2019 - 201912020 - 20234

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    In silico analysis of elastomer-coated cerclage for reducing sternal cut-through in high-risk patients
    (The American Society of Mechanical Engineers (ASME), 2021) Erdoğan, Mustafa Bilge; N/A; N/A; N/A; Department of Mechanical Engineering; Department of Mechanical Engineering; Subaşı, Ömer; Oral, Atacan; Torabnia, Shams; Erdoğan, Deniz; Lazoğlu, İsmail; PhD Student; PhD Student; PhD Student; Undergraduate Student; Faculty Member; Department of Mechanical Engineering; Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; N/A; 179391
    Background: AISI 316 L stainless steel wire cerclage routinely used in sternotomy closure causes lateral cut-through damage and fracture, especially in cases of high-risk patients, which leads to postoperative complications. A biocompatible elastomer (Pellethane(R)) coating on the standard wire is proposed to mitigate the cut-through effect. Methods: Simplified peri-sternal and transsternal, sternum-cerclage contact models are created and statically analyzed in a finite element (FE) software to characterize the stress-reduction effect of the polymer coating for thicknesses between 0.5 and 1.125 mm. The performance of the polymer-coated cerclage in alleviating the detrimental cortical stresses is also compared to the standard steel cerclage in a full sternal closure FE model for the extreme cough loading scenario. Results: It was observed via the simplified contact simulations that the cortical stresses can be substantially decreased by increasing the coating thickness. The full closure coughing simulation on the human sternum further corroborated the simplified contact results. The stress reduction effect was found to be more prominent in the transsternal contacts in comparison to peri-sternal contacts. Conclusions: Bearing in mind the promising numerical simulation results, it is put forth that a standard steel wire coated with Pellethane will majorly address the cut-through complication.
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    In silico analysis of modular bone plates
    (Elsevier, 2021) N/A; N/A; Department of Mechanical Engineering; N/A; Department of Mechanical Engineering; Subaşı, Ömer; Oral, Atacan; Noyan, Sinan; Tunçözgür, Orçun; Lazoğlu, İsmail; PhD Student; PhD Student; Undergraduate Student; Master Student; Faculty Member; Department of Mechanical Engineering; Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; 179391
    Background: Inventory management or immediate availability of fracture plates can be problematic since for each surgical intervention a specific plate of varying size and functionality must be ordered. Modularization of the standard monolithic plate is proposed to address this issue. Methods: The effects of four different unit module design parameters (type, degree of modularization, connector screw diameter, sandwich ratio) on the plate bending stiffness and failure are investigated in a finite element four-point-bending analysis. A chosen, best-performing modular plate is then tested in silico for a simple diaphyseal tibial fracture scenario under anatomical compressional, torsional, and bending loads . Results: A modularization strategy is proposed to match the monolithic plate bending properties as closely as possible. With the best combination of design parameters, a fully modularized equivalent length plate with a 42.3% decrease in stiffness and 46.2% decrease in strength could be assembled. The chosen modular plate also displayed sufficient mechanical performance under the fracture fixation scenarios for a potentially successful osteosynthesis. Conclusions: Via computational methods, the viability of the modularization strategy as an alternate to the traditional monolithic plate is demonstrated. As a further realized advantage, the modular plates can alleviate stress shielding thanks to the reduced stiffness.
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    A novel approach to tube design via von Mises probability distribution
    (Taylor & Francis Ltd) Subay, Şehmuz Ali; N/A; N/A; N/A; Department of Mechanical Engineering; Oral, Atacan; Subaşı, Ömer; Öztürk, Çağlar; Lazoğlu, İsmail; PhD Student; Researcher; PhD student; Faculty Member; Department of Mechanical Engineering; Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; N/A; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 179391
    Discharge tube is a critical component in a reciprocating compressor that carries the refrigerant. It also transmits vibrations from compressor body to housing, making the design of tube a complex engineering problem combining static, modal and flow behaviour. This study proposes a novel design algorithm for discharge tube, to decrease the dependency on the trial-and-error approach commonly used by manufacturers. The computational approach creates a tube that connects the inlet and outlet using von Mises probability distribution. The created geometries are checked for static and dynamic properties using FEA. The algorithm continues until a candidate design passes the imposed thresholds. The candidate designs perform similarly to benchmark in evaluated aspects, demonstrating promising results. The presented algorithm is successful in generating alternative tube designs from scratch and can accommodate varying requirements. The main novelty of this study is the development of a comprehensive decision algorithm that considers multiple engineering parameters simultaneously.
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    Effect of starting position of crankshaft on transient body vibrations of reciprocating compressor
    (Elsevier, 2023) Sahin C.; Haque U.U.; N/A; N/A; Department of Mechanical Engineering; Oral, Atacan; Subaşı, Ömer; Lazoğlu, İsmail; PhD Student; PhD Student; Faculty Member; Department of Mechanical Engineering; Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 179391
    The maximum reciprocating compressor vibrations occur during the startup and shutdown operations and understanding the factors that influence the transient vibrations can help in developing solutions to reduce the excessive displacements. In this study, the effect of crankshaft starting position on the vibration phenomenon is investigated and the optimal starting position to deliver a smooth start is proposed. The structural forces are analytically modeled to estimate the body displacements by considering the system resonance frequencies and modal vectors. An experimental setup is also constructed to validate the prediction model results, with the integration of an encoder to track the crankshaft angular position and transducers to measure the discharge and suction pressures. The transient responses of three different crankshaft start positions are then compared using the experimental setup and the analytical model. The results indicate that if the crankshaft starts to rotate from positions close to the bottom dead center, a higher amount of startup vibrations is observed, revealing the optimal starting position zone. The magnetization effect can potentially be addressed by the sensorless starting strategy developed by Lee et al. (2008) that implements a phase current controller for a smoother startup. While out of scope for this study, shutdown strategies can also be devised to have the piston consistently land at the favorable SAP range. By separately investigating the instances when the ‘stop’ command is provided to the steady-state operating compressor, solutions that attempt to replicate the conditions that lead to the favorable stop position can be developed; a limiting factor in mass production will be implementing the encoder for continuous position tracking and an accompanying undesirable cost increase in manufacturing. Nevertheless, the investigation of passive and active strategies is ripe for research in literature. 2022 Elsevier Ltd and IIR
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    A novel adjustable locking plate (ALP) for segmental bone fracture treatment
    (Elsevier Sci Ltd, 2019) N/A; N/A; Department of Mechanical Engineering; Subaşı, Ömer; Oral, Atacan; Lazoğlu, İsmail; PhD Student; PhD Student; Faculty Member; Department of Mechanical Engineering; Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 179391
    A novel Ti6Al4V adjustable locking plate (ALP) is designed to provide enhanced bone stability for segmental bone fractures and to allow precise positioning of disconnected segments. The design incorporates an adjustable rack and pinion mechanism to perform compression, distraction and segment transfer during plate fixation surgery. The aim of this study is to introduce the advantages of the added feature and computationally characterize the biomechanical performance of the proposed design. Structural strength of the novel plate is analyzed using numerical methods for 4-point bending and fatigue properties, following ASTM standards. An additional mechanical failure finite element test is also conducted on the rack and pinion to reveal how much torque can be safely applied to the mechanism by the surgeon. Simulation results predict that the new design is sufficiently strong to not fail under regular anatomical loading scenarios with close bending strength and fatigue life properties to clinically used locking compression plates. The novel ALP design is expected to be a good candidate for addressing problems regarding fixation of multi-fragmentary bone fractures.
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    A novel transient vibration and noise reducer (TVR) for vibratory machines
    (Elsevier Ltd, 2022) Korkmaz, Cansın; N/A; N/A; Department of Mechanical Engineering; Oral, Atacan; Subaşı, Ömer; Lazoğlu, İsmail; PhD Student; Researcher; Faculty Member; Department of Mechanical Engineering; Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; N/A; College of Engineering; N/A; N/A; 179391
    Maximum vibration and maximum noise are generated during the transient startup and shut down operational phases of machines that demonstrate harmonic motion. Such vibrations and noise are especially undesired in household products. To abate such undesired effects associated with excessive body displacements and noise, a transient vibration and noise reducer (TVR) design is proposed, and a reciprocating compressor of a refrigerator is utilized in this study as an example. Polymer mount-spring sleeves with a stepwise geometry that allows free vibration during steady-state and vibration suppression only at transient phases are 3D printed to be installed at each leg of compressor body-outer housing linkage. Finite element analysis coupled design of experiments are conducted to characterize the vibration suppression response and to optimize the critical dimensional parameters of the TVR. The best candidate design is then implemented to a compressor to be compared against the performance of a compressor without the attachment of TVRs. The experimental results reveal a 51% decrease in peak transient displacement and a decrease from average 41 dBA to 25 dBA in peak transient noise level which are testaments to the success of the prospective design addition to the vibratory machines. © 2022 Elsevier Ltd