Researcher:
Lazoğlu, İsmail

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İsmail

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Lazoğlu

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Researcher Of Publications: search.filters.isAuthorOfPublication.6004e693-d61c-4c6f-9d78-c213559a4e99

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Now showing 1 - 10 of 147
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    Sculpture surface machining: a generalized model of ball-end milling force system
    (Elsevier Sci Ltd, 2003) N/A; Department of Mechanical Engineering; Lazoğlu, İsmail; Faculty Member; Department of Mechanical Engineering; College of Engineering; 179391
    A new mechanistic model is presented for the prediction of a cutting force system in ball-end milling of sculpture surfaces. The model has the ability to calculate the workpiece/cutter intersection domain automatically for a given cutter location (CL) file, cutter and workpiece geometries. Furthermore, an analytical approach is used to determine the instantaneous chip load (with and without runout) and cutting forces. In addition to predicting the cutting forces, the model also employs a Boolean approach for a given cutter, workpiece geometries, and CL file to determine the surface topography and scallop height variations alone, the workpiece surface which can be visualized in 3-D. The results of model validation experiments on machining Ti-6A1-4V are also reported. Comparisons of the predicted and measured forces as well as surface topography show good agreement.
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    Dynamic analysis of a novel moving magnet linear actuator
    (IEEE-Inst Electrical Electronics Engineers Inc, 2017) N/A; N/A; N/A; Department of Mechanical Engineering; Hassan, Adnan; Bijanzad, Armin; Lazoğlu, İsmail; PhD Student; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 179391
    A novel moving magnet linear actuator is proposed for linear oscillations in the linear resonant compressors for household refrigerators. This paper provides stator and armature design including CAD model and geometric parameters. Furthermore, the working principle of the proposed actuator is explained. The stator assembly is composed of two reversely wound coils, which are electrically excited with single phase ac power and oscillates the radially magnetized armature. With the help of the electromechanical analytical model, the dynamic parameters such as stroke, velocity, and acceleration of the armature are derived. Additionally, the time-dependent current model of the stator winding is proposed. An experimental setup is used to validate these responses at the resonance excitation frequency with the help of sensors. The system kinetics are discussed to estimate the spring, damping, inertial, and magnetic forces. A simulation is executed to estimate the time-domain responses of these dynamic parameters and the effects of excitation frequency are discussed. The force models are experimentally validated at the resonance frequency excitation. In order to evaluate the performance of the proposed actuator, a comparison of the performance parameters, such as efficiency, stroke, current, and mass flow rate is demonstrated with the conventional rotary as well as the linear motors for linear compressor application.
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    Flow simulation and optimization of a left ventricular assist device
    (American Society of Mechanical Engineers (ASME), 2007) Sorguven, Esra; Ciblak, Namik; Okyar, A. Fethi; Akgun, Mehmet A.; Egrican, A. Nilufer; Safak, K. Koray; Ahn, Hojin; Kucukaksu, Suha; Department of Mechanical Engineering; Lazoğlu, İsmail; Faculty Member; Department of Mechanical Engineering; College of Engineering; 179391
    Artificial assist devices offer a promising treatment option for patients with congestive heart failure, especially when the patient is not eligible for heart transplantation. In order to develop a left ventricular assist device an interdisciplinary research, involving engineering and medical research teams, is conducted. The left ventricular assist device investigated in this study is the MicroMed DeBakey VAD [1], an axial blood pump that provides flow from the left ventricle to the aorta. The geometry of this baseline design is generated via parametric modeling. An optimization surface around the baseline design is formed by using the design of experiments method. Accordingly, eighty parameter sets and the corresponding CAD models are created. Flow through these pumps is simulated at the operation point. Flow data are evaluated to predict the pump performance, blood damage and bearing friction. An axial pump, closer to the optimum, is found that provides 8635 Pa pressure increase at a flow rate of 6 l/min and a rotational speed of 10000 rpm. Pressure head of the selected pump is 18% higher and blood damage is 4% less than the baseline design.
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    A new model and direct slicer for lattice structures
    (Springer, 2021) N/A; N/A; Department of Mechanical Engineering; Mustafa, Syed Shahid; Lazoğlu, İsmail; PhD Student; Faculty Member; Department of Mechanical Engineering; Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; College of Engineering; N/A; 179391
    This paper presents a model for generating strut-based lattice structures using topology optimization and their efficient direct slicing. These structures exhibit better physical properties and can represent the partial densities at the macro-scale level, which often appear in designs based on topology optimization. The fabrication of such large member structures with intricate geometries is possible by the additive manufacturing technologies which offer design freedom to produce the optimized parts for engineering applications. However, these structures generate millions of planer manifolds describing the strut members and result in large data files, thus making conventional procedures in additive manufacturing highly ineffective. Therefore, the design process for such structures requires efficient data manipulation and storage of the lattice topology. In the current work, a mathematical model for the strut primitive which connects two nodes in a cell is developed. Based on the proposed strut model, a structural optimization formulation is presented for lattice structures design under volume fraction constraint. A matrix-oriented compact data structure to express the lattice topology and the direct slicing algorithm which makes queries on the proposed compact data structure is presented as part of this work. The slicing kernel has been tailored for parallel implementation to handle engineering-scale applications which often consist of structures over a million struts. The article is organized into the "Introduction" section explaining the requirement and the novelty of this work. Following which, the automated design framework based on topology optimization procedure for lattice structures is given. The mathematical derivations and data structure of the strut-based lattice will be explained and the operations on model data for the direct slicing procedure are elaborated. Numerical experiments verifying the proposed method will be presented toward the end.
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    Development of a finite element model of the human cervical spine
    (Turkish Neurosurgery Society, 2014) N/A; N/A; Department of Mechanical Engineering; N/A; Zafarparandeh, Iman; Erbulut, Deniz Ufuk; Lazoğlu, İsmail; Özer, Ali Fahir; PhD Student; Researcher; Faculty Member; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; School of Medicine; College of Engineering; School of Medicine; N/A; 37661; 179391; 1022
    The finite element model has been used as an effective tool in human spine biomechanics. Biomechanical finite element models have provided basic insights into the workings of the cervical spine system. Advancements in numerical methods during the last decade have enabled researchers to propose more accurate models of the cervical spine. The new finite element model of the cervical spine considers the accurate representation of each tissue regarding the geometry and material. The aim of this paper is to address the new advancements in the finite element model of the human cervical spine. The procedures for creating a finite element model are introduced, including geometric construction, material-property assignment, boundary conditions and validation. The most recent and published finite element models of the cervical spine are reviewed. / Sonlu eleman yöntemi efektif bir araç olarak omurga biyomekaniğinde yaygın kullanılmaktadır. Servikal omurga içerisinde meydana gelebilecek biyomekanik değişimlerin incelenmesine fırsat verebilmektedir. Geçtiğimiz on yıl içerisinde, geliştirilmiş olan nümerik metodlar sayesinde, daha gerçekçi omurga modellerinin çıkarılması sağlanmıştır. Günümüzde, servikal omurga modellerinde kullanılan geometri ve malzeme özellikleri olabildiğince gerçeğe yakın oluşturulabilmektedir. Bu makalenin amacı, sonlu eleman yöntemi kullanılarak insan servikal modellinin oluşturulmasını örneklerle açıklamaktır. Servikal omurga modelinin sonlu eleman yöntemi ile oluşturulmasının her bir adımı detaylı ele alınmıştır. Literatürde en son yayınlanan servikal omurga sonlu eleman modelleri incelenmiş ve karşılaştırılmıştır.
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    Feedrate scheduling strategies for free-form surfaces
    (Elsevier Sci Ltd, 2006) N/A; Department of Mechanical Engineering; N/A; Erdim, Hüseyin; Lazoğlu, İsmail; Öztürk, Burak; PhD Student; Faculty Member; N/A; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 179391; N/A
    Free-form machining is one of the commonly used manufacturing processes for several industries such as automobile, aerospace, die and mold industries. In 3D complicated free-form surfaces, it is critical, but often difficult, to select applicable cutting conditions to achieve high productivity while maintaining high quality of parts. It is essential to optimize the feedrate in order to improve the machining efficiency of the ball-end milling. Conservative constant feedrate values have been mostly used up to now since there was a lock of physical models and optimization tools for the machining processes. The common approach used in feedrate scheduling is material removal rate (MRR) model. In the MRR based approach, feedrate is inversely proportional to either average or instantaneous volumetric removal rate. Commonly used CAM programs and NC code generators based on only the geometric and volumetric analysis, but they do not concern the physics of the free-form machining process yet. The new approach that is also introduced in this paper is based on the mechanics of the process. In other words, the force-based models in which feedrate is set to values which keep either average or instantaneous machining forces to prescribed values. In this study, both feedrate scheduling strategies are compared theoretically and experimentally for 3D ball-end milling of free-form surfaces. It is shown that MRR based feedrate strategy outputs higher feedrate values compared to force based feedrate strategy. High feedrate values of the MRR strategy increase the cutting forces extensively which can be damaging to the part quality and to the CNC Machine. When the new force based feedrate-scheduling strategy introduced in this paper is used, it is shown that the machining time can be decreased significantly along the tool path. The force-based feedrate scheduling strategy is tested under various cutting conditions and some of the results are presented in the paper. (C) 2005 Elsevier Ltd. All rights reserved.
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    Analysis of thermal fields in orthogonal machining with infrared imaging
    (Elsevier Science Sa, 2008) Department of Mechanical Engineering; Department of Mechanical Engineering; Department of Physics; Lazoğlu, İsmail; Serpengüzel, Ali; N/A; Faculty Member; Faculty Member; Department of Mechanical Engineering; Department of Physics; Manufacturing and Automation Research Center (MARC); Manufacturing and Automation Research Center (MARC); N/A; College of Engineering; College of Engineering; College of Sciences; N/A; 179391; 27855
    The validation of a previously developed finite difference temperature prediction model is carried out for orthogonal machining process with a high precision infrared camera set-up, considering the temperature distribution in the tool. the thermal experiments are conducted with two different materials; al 7075, AISI 1050, with two different tool geometries; inserts having a rake angle of 6 degrees and 18 degrees, for different cutting velocities and feedrates. an infrared camera set-up is utilized for the thermal experiments. the results of the high precision infrared thermal measurements are compared with the outputs of the finite difference temperature model, considering the maximum and the mean temperatures in the tool-chip interface zone and the temperature distributions on the tool take face. the maximum tool-chip interface temperature increases with increasing cutting velocity and feedrate. the relationship between the maximum tool-chip interface temperature and the rake angle of the tool is not distinctive. the experimental results show good agreement with the simulations. (c) 2007 Elsevier B.V. all rights reserved.
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    A monolithic opto-coupler based sensor for contact force detection in artificial hand
    (Ieee, 2016) N/A; N/A; Department of Mechanical Engineering; Shams, Sarmad; Lazoğlu, İsmail; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 179391
    This paper presents a monolithic opto-coupler based force sensor design to detect the contact forces of the fingertip of the artificial hand during grasp process. Effective and precise measurement of the contact force is always a challenge for the humid and temperature varying environment. In this paper, we propose a novel design of force sensor with optical technique. The optical technique is preferred over other techniques because of its simpler electronics and less immunity to temperature variation under humid environment. Simulation results conducted using Finite Element Method (FEM) analysis confirmed the deflection is linear for the forces from 0 to +/- 100 N. The maximum stress found at 100 N is 252.39 MPa. Also, modal analysis is performed to ensure the sensor is durable and operative while handling different vibrating objects. Calibration experiment of the sensor is performed using multipoint calibration process and curve fitting technique.
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    Analysis of tool orientation for 5-axis ball-end milling of flexible parts
    (Elsevier, 2015) N/A; N/A; Department of Mechanical Engineering; Khavidaki, Sayed Ehsan Layegh; Yiğit, İsmail Enes; Lazoğlu, İsmail; PHD Student; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 179391
    This article investigates the effects of lead and tilt angles in 5-axis ball-end milling of flexible freeform aerospace parts by considering process mechanics. In current CAM technology, tool posture is determined by geometrical analysis only. However, in high-performance 5-axis milling, not only the geometry, but also the mechanics of the process is critical. Therefore, a new and comprehensive mechanics-based strategy is proposed for selection of tool postures considering process parameters such as cutting force, torque, part vibration, and surface quality. Effectiveness of the proposed strategy is validated by conducting experiments on 5-axis ball-end milling of flexible freeform structures. (C) 2015 CIRP.
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    Direct ink writing (DIW) of structural and functional ceramics: recent achievements and future challenges
    (Elsevier Sci Ltd, 2021) N/A; Department of Mechanical Engineering; Shahzad, Aamir; Lazoğlu, İsmail; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 179391
    Along with vast research on the additive manufacturing (AM) of polymeric and metallic materials, three-dimensional (3D) manufacturing of ceramic materials is now the modern trend. Among all the additive manufacturing techniques, Direct Ink Writing (DIW) permits the ease of design and rapid manufacturing of ceramic-based materials in complicated geometries. This paper presents an outline of the contributions and tasks in the fabrication 3D ceramic parts by the DIW technique. The current state-of-the-art manufacturing of various ceramics such as alumina, zirconia, and their composites through Direct Ink Writing (DIW) is described in detail. Moreover, this review paper aims at the innovations in the DIW approach of ceramic materials and introduces the progression of the DIW for the manufacturing of ceramics. Most importantly, the DIW technique has been explained in detail with illustrations. The prospects and challenges related to the DIW technique are also underscored.