Makine Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.11779/1944

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Assessment of the Models for Predicting the Responses of Spherical Objects in Viscoelastic Mediums and at Viscoelastic Interfaces
(IOP Publishing Ltd, 2021) Körük, Hasan
Spherical objects, such as bubbles and spheres, embedded in mediums and atviscoelastic interfaces are encountered in many applications, including the determination ofmaterial properties. This paper assesses the models for predicting the responses of sphericalobjects in viscoelastic mediums and at viscoelastic interfaces used in various applications. Themodels are presented very compactly, and evaluations are performed based on the analyses ofthe models for the spherical objects in viscoelastic mediums and at viscoelastic interfaces. First,the models for predicting the static displacements of spherical objects are presented andassessed. After that, the models for predicting the dynamic responses of spherical objects arepresented and their dynamic behaviours are compared. Then, the models for the deformation ofthe medium around spherical objects and stress distribution are presented and evaluated. Themodels and evaluations presented in this study can be exploited in various applications,including biomedical applications.
The Minimum Variance Distortionless Response Beamformer for Damage Identification Using Modal Curvatures
(Association of American Publishers, 2023) Eroğlu, Uğurcan; Pau, A.
This study presents a damage identification procedure in beams based on the use of beamforming algorithms, which are mostly utilized in inverse problems of source identification and image reconstruction. We choose the modal curvatures as observed quantities and compare the performance of the Bartlett beamformer, minimum variance distortionless response (MVDR) processor, and of a conventional objective function based on the modal curvatures. By means of a set of experiments, we show that the MVDR processor can overcome some of the difficulties encountered with other estimators, especially in cases of slight damage, or damage located between two sensors. © 2023, Association of American Publishers. All rights reserved.
Citation - Scopus: 6
On the Difficulties in Manufacturing of Luffa Fibers Reinforced Biocomposites and Variations in Their Dynamic Properties
(Institute of Noise Control Engineering, 2016) Genç, Garip; Körük, Hasan
Defects in raw bio materials such as luffa plant effect the characteristics of the composites of these materials. These defects results in structural differences and large scattering mechanical properties such as density, damping and elasticity modulus. There are difficulties during the manufacturing of the composites from bio materials inherent to their nature. The major problems and restrictions encountered with the use of green luffa materials as reinforcement are studied in this study. First, the structural differences in the raw luffa plants are presented and the difficulties in their manufacturing are discussed. After that, the variations in measured modal parameters of luffa composites such as natural frequencies and loss factors and mechanical properties such as density and elasticity modulus are presented. Some solutions are provided to minimize the problems in manufacturing and identifying properties of luffa composites. The results show that the luffa composites can be produced with similar properties without any special selection of fibers to homogenize the batches of fibers for controlling the defects. However, a preliminary selection of fibers is required if the mechanical or dynamic properties of the luffa composites are desired to have small variations.
Technology of Mental Functional Representations as a First Stage of Conceptualization and Implementation of Complex Scientific Knowledge in Innovation Processes
(Transfer-Innovations, 2019) Dorantes-Gonzalez, Dante Jorge; Balsa-Yepes, Aldrin
In innovation processes, it is common to deal with highly cross-multidisciplinary topics. For example, an innovation process may integrate psychological, neuroscientific, biological and engineering disciplines, among many others dealing with bio-cybernetic systems. One specific type of those theories is related to cognitive processes, knowledge representation, and self-learning systems. Therefore, there is a need to easily and rapidly understand, as well as apply and share knowledge of complex theories by innovation managers, engineers, scholars, training practitioners, computational modelers, managers, and stakeholders, among others. In this regard, the present article provides with a graphical tool to represent complex cross- multidisciplinary theories, concepts and processes in a simple, concise, and logical manner, by using functional principles and graphical representations that have been successfully used in engineering and technology areas such as adaptive control systems, algorithmic flow charts, and computational cognitive neuroscience. Once described the models that have been typically used to represent and model knowledge and cognition, functional cognitive modeling is introduced, and then applied to represent and model complex cognitive theories from psychology and neuroscience such as Jean Piaget’s Theory of Intellectual Growth, Antonio Damasio’s Somatic Marker Hypothesis, and Dante Dorantes’ Soft Skills Model.
Advances on Laser-Generated Surface Acoustic Wave-Based Characterization of Thin Films and Skin Tissues
(2016) Dorantes-Gonzalez, Dante Jorge
...
A Novel Business Model Frame for Innovative Startups - (may 12-14, 2017)
(World Conference on Technology, Innovation and Entrepreneurship, 2017) Dorantes-Gonzalez, Dante Jorge
The business model canvas has been used in business and entrepreneurship to sketch and frame the key points behind the development of a startup, and it was meant to strategically analyze and develop startups or documenting existing businesses. The business model canvas describes the firm’s value proposition, partners, resources, activities, customer relationships, distribution channels, customers, revenue streams and cost structure. However, when it comes to innovative startups, this template does not explicitly include innovation measures, no problem/opportunity formulation, or even such a basic component of a business model, as the profit formula. The present paper proposes a novel business model frame to visually and concisely sketch, besides accurately state traditional business concepts, key innovation concepts that any startup should integrate to be a game-changer in a competitive market. This new model is based on a combination of key principles of the theory of inventive problem solving (TRIZ) applied to business and management, such as multi-screen analysis of value-conflict mapping, trends of ideality of business system evolution positioning, among others; but also intellectual property, disruptive strategies, and open innovation, as well as startup metrics to describe the business differentiation and attractiveness to potential investors, incubators and accelerators.
Citation - Scopus: 3
Identification of Material Viscoelastic Properties Using the Motion of a Rigid Sphere Located at Tissue-Mimicking Material Interface in Response To a Dynamic Force
(Trans Tech Publications, 2022) Koç, Hayati Ömer; Körük, Hasan; Beşli, Ayça; Yurdaer, Berk Salih
The motion of a rigid sphere located at tissue-mimicking material interface in response to a dynamic force of short duration for the purpose of the determination of material viscoelastic properties was investigated in this study. The experiments were performed using a rigid sphere located at tissue-like material (gelatin phantom) interfaces. An electromagnet was used to apply the desired dynamic force to the sphere and a high-speed camera was used to track the movement of the sphere. Using the experimentally measured response of the sphere and the dynamic response of the sphere predicted by a sophisticated analytical model of the sphere located at a medium interface, the shear modulus, density and damping of the tissue-mimicking material were determined. The procedure followed in this study successfully produced the shear modulus, density and viscous damping ratio of the 20% (and 30%) gelation phantom as 1320 Pa, 1040 kg/m3 and 0.12 (and 2580 Pa, 1180 kg/m3 and 0.2), respectively. As the sophisticated theoretical model that is valid for small and large sphere displacements includes many parameters for the system such as the mass and size of the sphere, the inertia force of the medium involved in motion and the radiation damping due to shear waves and the experimental setup is very straightforward, it is believed that the procedure proposed in this study can be widely exploited to identify accurate material viscoelastic properties in practice.
The Direct Numerical Simulation of the Deflected Wake Phenomenon Around a Plunging Naca0012 Airfoil at Low Reynolds Numbers
(2015) Yılmaz, S.B.; Sahin, Mehmet; Ünal, M. Fevzi
...
17th International Conference on Mechatronics Technology, October 15-18, 2013, Jeju Island, Korea
(Elsevier, 2015) Hwang, Sung Ho; Kim, Joon-wan; Dorantes-Gonzalez, Dante Jorge
In recent years, Mechatronics has gained a lot of interest as more applications have been introduced to industry and society. The need for new mechatronic technologies in the form of advanced production systems, mechatronic devices, control systems, robotics, biomedical applications, MEMS, and measurement systems, among others, is very much required in improving productivity and competitiveness in many industries. Thus, this conference was organized to address the state-of-the-art technology for the benefit of researchers and users, and this time the conference made a special focus on the topic: Sustainable Mechatronics Technology.
Tri̇bi̇ne Vertical Axis Wind Turbine Efficiency Analysis
(TÜBİTAK, 2019) Dorantes-Gonzalez, Dante Jorge; Layegh Khavidaki, Seyed Ehsan
Proje konusu, savonius tip dikey eksenli rüzgar türbini verim kıyaslamasıdır. Proje kapsamında dört farklı yarim cembersel tasarimli model tasarlanmış ve karşılaştırılması yapılmıştır. Bu modeller bıçaklar arası açıklık ve bıçak sayısının model üzerindeki verim etkisini gözlemlemeyi hedef almıştır.
Citation - WoS: 5
Citation - Scopus: 7
Development of an Improved Mathematical Model for the Dynamic Response of a Sphere Located at a Viscoelastic Medium Interface
(IOP, 2021) Körük, Hasan
A comprehensive investigation on the static and dynamic responses of a sphere located at elastic and viscoelastic medium interfaces is performed in this study. First, the mathematical models commonly used for predicting the static displacement of a sphere located at an elastic medium interface are presented and their performances are compared. After that, based on the finite element analyses, an accurate mathematical model to predict the static displacement of a sphere located at an elastic medium interface valid for different Poisson's ratios of the medium and small and large sphere displacements is proposed. Then, an improved mathematical model for the dynamic response of a sphere located at a viscoelastic medium interface is developed. In addition to the Young's modulus of the medium and the radius of the sphere, the model takes into account the density, Poisson's ratio and viscosity of the medium, the mass of the sphere and the radiation damping. The effects of the radiation damping, the Young's modulus, density and viscosity of the medium and the density of the sphere on the dynamic response of the sphere located at a viscoelastic medium interface are explored. The developed model can be used to understand the dynamic responses of spherical objects located at viscoelastic medium interfaces in practical applications. Furthermore, the proposed model is a significant tool for graduate students and researchers in the fields of engineering, materials science and physics to gain insight into the dynamic responses of spheres located at viscoelastic medium interfaces.
Citation - WoS: 7
Citation - Scopus: 9
Displacement of a Bubble Located at a Fluid-Viscoelastic Medium Interface
(Acoustical Society of America, 2019) Körük, Hasan; Choi, James J.
A model for estimating the displacement of a bubble located at a fluid-viscoelastic medium interface in response to acoustic radiation force is presented by extending the model for a spherical object embed- ded in a bulk material. The effects of the stiffness and viscosity of the viscoelastic medium and the amplitude and duration of the excitation force on bubble displacement were investigated using the proposed model. The results show that bubble displacement has a nonlinear rela- tionship with excitation duration and viscosity. The time at which the steady state is reached increases with increasing medium viscosity and decreasing medium stiffness.
Citation - WoS: 8
Citation - Scopus: 9
Identification of Crack Noises in Household Refrigerators
(Elsevier, 2015) Körük, Hasan; Arısoy, Ahmet
The crack noises propagating from a refrigerator disturb residents in a household; however, the reasons behind the mechanisms of such noises have not been identified yet. In this study, the crack noises in modern household refrigerators are identified and their root causes are explored. The appropriate parameters for overall and Fourier analyses are first determined and the noise characteristics of typical household refrigerators under various conditions are presented. Then, a special test rig providing remote control of the subcomponents including the compressor, fan and heater is designed and structural acceleration and sound pressure measurements inside and outside the test rig in a quiet room are performed. The acoustic and vibration measurements are conducted under various conditions by separately controlling each subcomponent. The crack noises in typical household refrigerators are identified and their root causes are explored by using the results of the overall and Fourier analyses. Some solutions to minimize the crack noises in household refrigerators are also summarized.
Citation - WoS: 4
Citation - Scopus: 4
Vibration of Locally Cracked Pre-Loaded Parabolic Arches
(Academic Press, 2022) Tüfekci, Ekrem; Eroğlu, Uğurcan; Giuseppe, Ruta
We study linear dynamics of an initially parabolic arch deformed by a uniform ‘dead’ load. The arch is seen as a fully deformable one-dimensional continuum with rigid cross-sections, one of which suffers from a small local crack at its boundary. The crack is simulated by springs, the stiffnesses of which are evaluated via stress intensity factors. By two first-order perturbations we investigate a non-trivial equilibrium adjacent to the reference configuration and small vibration superposed on it. The modulation of the initial load on the natural angular frequencies and its consequences on damage detection is described and commented. It turns out that neglecting the initial load, recalling for actual ‘dead’ structural actions, can be misleading in damage identification, while its inclusion leads to better results.
Method and Device for Acoustic Particle Palpation
(2017) Choi, James; Körük, Hasan
The present invention relates to a method of measuring the elasticity of a material of interest, the method comprising palpation of the material of interest using at least one acoustically responsive particle which has been administered into or adjacent to said material, wherein said palpation comprises the use of acoustic waves to push the at least one acoustically responsive particle against the material of interest to cause transient deformation of the material and measuring the transient deformation of the material and/or the force response. The present invention also relates to a device for palpating a material of interest with at least one acoustic ally responsive particle and measuring the resulting deformation of the material of interest and/or force response, the device compris ing a palpation component comprising one or more transducers configured to generate an acoustic wave suitable for pushing at least one acoustically responsive particle against the material of interest to cause transient deformation of the material of interest within a region of palpation and an active monitoring component configured to actively image the material of interest and/or the acoustically responsive particle.
Citation - WoS: 27
Citation - Scopus: 28
Development of a New Integrated Energy System With Compressed Air and Heat Storage Options
(Elsevier, 2020) Javania, Nader; Dinçer, İbrahim; Karapekmez, Aras
The present study investigates a biomass driven power plant integrated with compressed air and thermal energy storage subsystems. Compressed air energy storage system exploits the pressurized air at non-peak periods to be used in peak times when there is a need for extra energy. Thermal energy storage systems including phase change material, allow the solar subsystem to operate independently in order to produce hot air when solar irradiation is insufficient. The energy stored in the present system is then supplied to both the gasifier and combustion chamber in order to achieve a higher combustion efficiency. Three different phase change materials (PCMs) are investigated and their efficiencies are comparatively evaluated. Among the considered PCMs, LiNO3 is the most suitable material for the considered system with 82% energy efficiency and 84% exergy efficiency. The current study also aims at designing a renewable energy based power plant which operates continuously through using storage subsystems and is more environmental benign compared to fossil fuel based conventional systems. In this regard, wet wood (CH1.46O0.64N0.002) with 15% moisture content is selected as a fuel instead of fossil-based fuels in order to reduce the greenhouse gas emissions and eliminate the dep endency on fossil fuels. A comprehensive thermodynamic analysis is conducted to evaluate the entropy generations, exergy destructions, and energy and exergy efficiencies. The highest overall energy and exergy efficiencies are obtained as 28.58% and 24.08% in the discharging period, respectively.
Citation - WoS: 4
Citation - Scopus: 4
Application of Ultrasonic Vibrations for Minimization of the Accumulation of Limescale in Steam Irons
(Elsevier, 2018) Körük, Hasan; Şanlıtürk, Kenan Yüce; Serenli, Muzaffer
The accumulation of limescale in steam irons can significantly reduce the ironing efficiency. It is this problem that inspired us to introduce ultrasonic vibrations to irons in order to minimize limescale accumulation. This study describes a methodology for designing, modelling and optimizing an iron fitted with an ultrasonic exciter in an attempt to minimize limescale accumulation. In our methodology, first, an experimental demonstration of the potential benefits of ultrasonic vibrations in steam irons was conducted, using two existing irons, one of which was equipped with an ultrasonic exciter. Having confirmed the benefits, an experimental iron was designed and then optimized to maximise ultrasonic vibrations using finite element analyses within a predefined frequency range. To validate the results of the finite element analyses, a prototype iron base was built, and forced vibrations of this prototype, at ultrasonic frequencies ranging from 35 to 40 kHz, were measured using a laser vibrometer. The results of the theoretical and experimental vibration analyses as well as the physical experiments on the steam irons indicate that it is possible for ultrasonic vibrations to be utilized in irons to minimize the accumulation of limescale.
Citation - Scopus: 2
Strong Transient Effects of the Flow Around a Harmonically Plunging Naca0012 Airfoil at Low Reynolds Numbers
(Springer, 2015) Yücel, S. Banu; Şahin, Mehmet; Ünal, M. Fevzi
Abstract The flow pattern around a NACA0012 airfoil undergoing harmonic plunging motion corresponding to the deflected wake phenomenon reported by Jones and Platzer (Exp Fluids 46:799–810, 2009) is investigated in detail using direct numerical simulations. An arbitrary Lagrangian–Eulerian formulation based on an unstructured side-centered finite volume method is utilized in order to solve the incompressible unsteady Navier–Stokes equations. The Reynolds number is chosen to be 252, and the reduced frequency of plunging motion (k = 2?fc/U?) and the plunge amplitude non-dimensionalized with respect to chord are set to be 12.3 and 0.12, respectively, as in the experimental study of Jones and Platzer (2009). The present numerical simulations reveal a highly persistent transient effect, and it takes two orders of magnitude larger duration than the heave period to reach the time-periodic state. In addition, the three-dimensional simulation reveals that the flow field is three-dimensional for the parameters used herein. The calculation reproduces the deflected wake and shows a good agreement with the experimental wake pattern. The instantaneous vorticity contours, finite-time Lyapunov exponent fields and particle traces are presented along with the aerodynamic parameters including the lift and thrust coefficients.
Citation - WoS: 12
Citation - Scopus: 12
Mechanics of Milling 48-2 Gamma Titanium Aluminide
(Elsevier, 2020) Layegen, S. Ehsan; Lazoğlu, İsmail; Hussain, Abbas; Arrazola, Pedro-J.; Subaşı, Ömer; Yavaş, Çağlar; Lazcano, Xabier; Öztürk, Çağlar; Yiğit, İ. Enes; Aristimuno, Patxi-X.
Accurate and fast prediction of cutting forces is important in high-performance cutting in the aerospace industry. Gamma titanium aluminide (gamma-TiAl) is a material of choice for aerospace and automotive applications due to its superior thermo-mechanical properties. Nevertheless, it is a difficult to machine material. This article presents the prediction of cutting forces for Ti-48Al-2Cr-2Nb (48-2-2) gamma-TiAl in milling process using orthogonal to oblique transformation technique. The novelty of this paper lies in reporting the orthogonal database of 48-2-2 gamma-TiAl. Fundamental cutting parameters such as shear stress, friction angle and shear angle are calculated based on experimental measurements. Friction coefficients are identified for two different coating conditions which are AlTiN, and AlCrN on carbide tools. Predicted results are validated with the experimental cutting forces during end milling and ball-end milling operations for different cutting conditions. The simulated results showed good agreement with the experimental results, which confirms the validity of the force model
Citation - WoS: 19
Citation - Scopus: 26
Jute and Luffa Fiber-Reinforced Biocomposites: Effects of Sample Thickness and Fiber/Resin Ratio on Sound Absorption and Transmission Loss Performance
(Taylor & Francis, 2021) Şanlıtürk, Kenan Y.; Genç, Garip; Körük, Hasan; Özcan, Ahmet Cihan
The acoustic properties of natural fiber-reinforced composites should be identified before using these materials in various engineering applications including sound and vibration isolation. This study investigates the effects of sample thickness and fiber/resin ratio on the acoustic performance of jute and luffa fiber-reinforced biocomposites. For this purpose, jute and luffa composite samples with different thicknesses and fiber/epoxy ratios are manufactured and their sound absorption coefficients (SACs) and transmission losses (TLs) are determined using impedance tube method. Thickness-dependent tendencies of the SACs and TLs of jute and luffa composites for low-, medium-, and high-frequency ranges are identified. The effect of fiber/epoxy ratio on the acoustic properties of jute and luffa composites as a function of frequency are determined. Furthermore, the SACs and TLs of some natural fiber-based samples with different thicknesses are predicted using mathematical models and the theoretical and experimental results are compared and evaluated.

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