Makine Mühendisliği Bölümü Koleksiyonu

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

Browse

Now showing 1 - 20 of 26

Citation - Scopus: 5
18 - Acoustic and Mechanical Properties of Biofibers and Their Composites
(Elsevier, 2022) Koç, Büşra; Genç, Garip; Körük, Hasan
In this study, the acoustic and mechanical properties of many biofibers and their composites are presented. First, the sound absorption coefficients and transmission losses of commonly used natural fibers and their composites are presented, by clearly reporting the thickness of the samples, for three different frequency ranges (<500 Hz: low, 500–2000 Hz: medium, and >2000 Hz: high). In addition, the sound absorption coefficients (for low- and medium-frequency ranges) and noise reduction coefficients of some 40-cm-thick samples are overlaid in order to directly compare their performances. Second, the physical properties, such as the density, diameter, and length of biofibers, and mechanical properties, such as the damping (or loss factor) and Young’s modulus of biofibers and their composites, are presented in detail. For comparison purposes, the acoustic and mechanical properties of some conventional materials, such as carbon and glass fibers, are included in the tables and figures. Finally, the effects of some parameters, such as pretreatment, fiber diameter, fiber/matrix ratio, moisture content, manufacturing and machining parameters/techniques, and measurement conditions/methods, on the acoustic and mechanical properties of natural materials are presented. Furthermore, current applications and potential usage areas of natural fibers are briefly discussed.
Citation - Scopus: 3
19 - Identification of the Elastic and Damping Properties of Jute and Luffa Fiber-Reinforced Biocomposites
(Elsevier, 2022) Genç, Garip; Saygılı, Yusuf; Körük, Hasan; Şanlıtürk, Yusuf Kenan
Although there are many studies in the literature on the static mechanical properties of biomaterials such as tensile strength, the dynamic mechanical properties of biomaterials such as modal loss factors have not been investigated in detail. In this study, the Young’s moduli and damping (or loss factors) of some jute and luffa fiber-reinforced biocomposites are investigated. The effects of fiber/resin ratio and thickness on the mechanical properties of the jute and luffa composites are identified via an experimental approach. For this purpose, acoustic and structural frequency response functions of some homogeneous and hybrid jute and luffa composite plates with different fiber/resin ratios and thicknesses are measured. By analyzing the measured frequency response functions using the circle-fit method, the modal frequencies and loss factors of the homogeneous and hybrid composite plates are determined. By assuming that the homogeneous plates are isotropic, the same plates are modeled using the finite element method, and by comparing the experimental and theoretical natural frequencies, the elastic properties of the homogeneous plates are determined. In addition, the same homogeneous plates are modeled by considering an anisotropic material model, and the associated material properties are determined. By using the identified material properties, the finite element models of the hybrid composite plates are developed, and by comparing their experimental and theoretical natural frequencies, the identified elastic material properties are evaluated and validated.
A Business Model Frame for Innovative Startups - (july 11-15, 2017)
(Global Business & Technology Association, 2017) Dorantes-Gonzalez, Dante Jorge
Current business model frames such as the Business Model Canvas and the Lean Canvas do not address aspects of open innovation, problem statement, innovative problem solving, business metrics and disruptive strategies; therefore, a novel business model frame is introduced to cover these aspects. This new model is based on a combination of key principles of the theory of inventive problem solving 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. The entrepreneur designing his/her own startup should be able to justify if not all, most of the items to be able to demonstrate the idea strengths. And regarding both building blocks “Product Formulation and Inventive Problem Solving” and “Disruption Strategy”, certain training should be necessary.
A Novel Business Model Frame for Innovative Startups – (Article)
(2017) Dorantes-Gonzalez, Dante Jorge
Purpose- This paper presents a novel business model frame that is meant to explicitly include several approaches of the Theory of Inventive Problem Solving, disruptive strategies, business metrics, problem statement and opportunity formulation, as well as improvements on the profit formula. Methodology- The analysis first addresses the business model canvas, sketching and framing key points behind the development of startups. The analysis on existing business models covers the firm’s value proposition, partners, resources, activities, customer relationships, distribution channels, customers, revenue streams and cost structure. When it comes to innovative startups, the author emphasizes that existing template do not explicitly include innovation measures, no problem/opportunity formulation, intellectual property, or even basic business model concepts as the profit formula. Hence, an innovative frame is developed primarily using the Theory of Inventive Problem Solving technique 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. Findings- A novel frame is proposed, providing general guidelines for each of the sections. Any entrepreneur designing his/her own startup should be able to justify, if not all, most of the items to be able to demonstrate the idea strengths. Regarding the specific building blocks: “Product Formulation and Inventive Problem Solving” and “Disruption Strategy”, certain short training should be necessary. Conclusion- The proposed business model frame visually and concisely sketches, besides accurately stating traditional business concepts, the key innovation concepts that any startup should integrate to be a game-changer in a competitive market. The developed frame is a helpful mapping and evaluation tool to accurately describe the business differentiation and innovation attractiveness to potential investors, incubators and accelerators.
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.
Advances on Laser-Generated Surface Acoustic Wave-Based Characterization of Thin Films and Skin Tissues
(2016) Dorantes-Gonzalez, Dante Jorge
...
Citation - WoS: 2
Citation - Scopus: 2
Approximate Closed-Form Solutions for Vibration of Nano-Beams of Local/Non-local Mixture
(Springer, 2022) Ruta, Giuseppe; Eroğlu, Uğurcan
This paper presents an approach to natural vibration of nano-beams by a linear elastic constitutive law based on a mixture of local and non-local contributions, the latter based on Eringen's model. A perturbation in terms of an evolution parameter lets incremental field equations be derived; another perturbation in terms of the non-local volume fraction yields the variation of the natural angular frequencies and modes with the 'small' amount of non-locality. The latter perturbation does not need to comply with the so-called constitutive boundary conditions, the physical interpretation of which is still debated. The possibility to find closed-form solutions is highlighted following a thorough discussion on the compatibility conditions needed to solve the steps of the perturbation hierarchy; some paradigmatic examples are presented and duly commented.
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.
Biyomalzemelerin Akustik ve Mekanik Özelliklerinin Arastırılması
(2020) Genç, Garip; Körük,Hasan
Bu proje kapsamında, jüt lifleri ve çesitli luffa lifleri kullanılarak, farklı kalınlıklarda reçinesiz (hiçbir reçine kullanılmayan) homojen ve hibrit jüt ve luffa yapılar ve yine farklı kalınlıklarda ve farklı lif/reçine oranlarında reçineli homojen ve hibrit jüt ve luffa yapılar üretilerek, bu yapıların akustik ve mekanik özellikleri ile ilgili kapsamlı bir resmin ortaya konulması hedeflenmistir. Bu kapsamda kullanılan yöntemler/sonuçlar su sekildedir: (i) Akustik testler için farklı kalınlıklarda hem reçinesiz hem de farklı lif/reçine oranlarına sahip reçineli homojen ve hibrit numuneler üretilmistir. Empedans tüp yöntemi kullanılarak bu akustik numunelerin ses yutma ve ses iletim kaybı gibi akustik özellikleri deneysel olarak belirlenmistir. Homojen ve hibrit kompozit yapıların akustik performansları karsılastırılmıstır. Sonuçta, kalınlık ve lif/reçine oranın bu yapıların akustik özellikleri üzerindeki etkisi ortaya konulmustur. (ii) Farklı frekans aralıkları için kalınlıgın ve lif/reçine oranının bir fonksiyonu olarak ölçülen akustik verilere egriler uydurularak, malzemelerin akustik özelliklerini belirlemeye yönelik basit ampirik modeller ortaya konulmustur. Dahası, malzemelerin ses yutma katsayıları Delany-Bazley ve Johnson- Champoux-Allard gibi teorik modeller kullanılarak tahmin edilmis ve sonuçlar deneysel sonuçlarla karsılastırılmıstır. Benzer sekilde, numunelerin ses iletim kayıpları teorik olarak hesaplanmıs ve deneysel sonuçlarla karsılastırılmıstır. Sonuçta, bu yapıların tasarımında akustik amaçla kullanılabilecek ampirik ve teorik modeller ortaya konulmustur. (iii) Titresim testleri için farklı kalınlık ve lif/reçine oranlarına sahip reçineli homojen ve hibrit numuneler üretilmis, üretilen bu yapılar üzerinde akustik ve yapısal frekans tepki fonksiyonları ölçülmüs ve aynı yapıların teorik modellerinden yararlanılarak malzemelerin elastik ve sönüm gibi mekanik özellikleri belirlenmistir. Homojen jüt ve luffa kompozit yapıları hem izotropik varsayılarak hem de bu yapıların yöne baglı elastik özelliklerinin olması durumu dikkate alınarak modellenmislerdir. Sonuçta, kalınlık ve lif/reçine oranın mekanik özellikler üzerindeki etkisi ortaya konulmus ve pratikte bu yapıların tasarımı için kullanılabilecek bazı yaklasımlar ortaya konulmustur.
Citation - WoS: 3
Citation - Scopus: 3
Characterization of Viscoelastic Materials Using Free-Layered and Sandwiched Samples: Assessment and Recommendations
(Polish Physical Society, 2015) Özer, Mehmet Sait; Körük, Hasan; Şanlıtürk, Kenan Yüce
Viscoelastic materials are widely used in many applications in practice. However, determination of the elastic and damping properties of these materials is quite difficult in the sense that the identified results may contain high degree of uncertainty. The characterization of viscoelastic materials using the Oberst beam method, based on non-contact excitation and response measurements, is revisited in this paper. The effects of signal processing parameters such as frequency resolution in Frequency Response Function (FRF) measurements, as well as the effects of various single-degree-of-freedom modal analysis methods, including circle-fit, half-power and line-fit are investigated first. Then, the modal loss factors, Young's modulus and shear modulus of some sample viscoelastic materials are identified using both the free-layered and sandwiched samples. The results obtained from different tests are compared, discussed and some recommendations are made so as to identify the damping and elastic properties of typical viscoelastic materials with better accuracy. Analyses of a large number of FRF measurements show that the selection of the appropriate signal processing parameters and the use of appropriate modal analysis method can be very significant during the identification of viscoelastic materials. By following the approach presented in this paper, the damping and elastic properties of viscoelastic materials can be identified with better accuracy using either free-layered or sandwiched samples. The material properties obtained by this approach can be used for developing valid structural models and/or for damping optimization purposes.
Development of a Model for Predicting Dynamic Response of a Sphere at Viscoelastic Interface: a Dynamic Hertz Model
(IOP Publishing Ltd, 2021) Körük, Hasan
A model for predicting the dynamic response of a sphere at viscoelastic interface is presented. The model is based on Hertz contact model and the model for a sphere in a medium.In addition to the elastic properties of medium and the size of sphere, the model considers thedensity of sphere, the density and viscosity of medium, and damping of oscillations of spheredue to radiation of shear waves. The model can predict not only the effects of the mechanicalproperties of medium, the physical properties of sphere, and the amplitude of excitation forceon sphere displacement, but also the effects of these parameters on shift of resonancefrequency. The proposed model can be used to identify the elastic and damping properties ofmaterials, and to understand the dynamic responses of spherical objects at viscoelasticinterfaces in practical applications.
Citation - WoS: 4
Citation - Scopus: 6
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.
Improved Business Model Representation of Innovation Concepts
(World Conference on Technology, Innovation and Entrepreneurship, 2015) Dorantes-Gonzalez, Dante Jorge; Küçükaydın, Hande; Özlem, Şirin; Bulgan, Gökçe; Aydın, Utkun; Son Turan, Semen; Karamollaoğlu, Nazlı; Teixeira, Frederico Fialho
Except for academics and consultants, the concept and purpose of innovation (not to mention related concepts such as “Open Innovation", "Free-Intellectual Property Innovation," or "Open Source Innovation") is usually unclear for most entrepreneurs and other practitioners. It often times happens that newly coined terminology becomes misleading or may even include a certain degree of sensationalism, hence turning into a matter of debate for specialists in the realm of technology management. Such has been the case for the term “Open Innovation”, since the word “open” is mainly related to crowd sourced innovation, but not for the openness on intellectual property rights. Since innovation is about the commercialization of original ideas, so we propose a simple and visual business model setting to resolve these concepts. To this regard, the “Business Model Canvas” has been used in business and entrepreneurship to sketch and frame the key points behind the development of a startup. This model was suggested by Alexander Osterwalder (2008) in his work on Business Model Ontology, as a strategic analysis template for developing startups or documenting existing businesses. It 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 such significant innovation components as intellectual property, its alignment to strategies, and intellectual property flow. The present paper proposes the use of an improved version of the Business Model Canvas to originally represent different models of innovation like Open Innovation, thus providing a clear, visual and quick representation of their meaning, and consequently, contribute to a better understanding of different concepts of innovation.
Citation - WoS: 15
Citation - Scopus: 18
Investigation of the Acoustic and Mechanical Properties of Homogenous and Hybrid Jute and Luffa Bio Composites
(Taylor & Francis, 2020) Garip Genç; Hasan Körük; Kenan Y. Sanlıtürk; Yusuf Saygılı
Design and development of new biomaterials has become a necessity due to adverse effects of chemical materials on people and nature. As the mechanical properties of biomaterials are not as good as those of chemical materials, their different configurations should be developed and tested before considering them for practical applications. Acoustic and mechanical properties of homogenous and hybrid jute and luffa biocomposites are investigated here. Homogenous and hybrid composites using jute and luffa fibers and epoxy are designed and manufactured and methods for identification of the acoustic and mechanical properties are summarized. Acoustic and structural frequency response functions are measured using homogenous and hybrid composite plates to determine their natural frequencies and loss factors. Using the experimental modal parameters of the plates and their theoretical models, elasticity moduli of biomaterials are determined. The acoustic absorption properties and transmission losses of homogeneous and hybrid composites are determined using impedance tube method. Results show that homogenous and hybrid jute and luffa composites can have moderate absorption coefficients (0.1 for a thickness of 4 mm) and superior damping performance of luffa and stiffness property of jute can be used together to produce hybrid composites with high damping (2.2–2.6%) and elasticity modulus (3–5 GPa).
Citation - WoS: 17
Citation - Scopus: 24
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.
Kabarcık Dinamiği için Gaz Basıncı Yasası
(2015) Delale, Can Fuat; Pasinlioglu, Şenay
...
Laser-Generated Surface Acoustic Wave-Based Study and Detection of Surface Cracks
(Int. Sc. & Tech. Conf. Beam technologies & Laser Applications, 2015) Chen, Kun; Fu, Xing; Li, Tingting; Dorantes-Gonzalez, Dante Jorge; Li, Yanning; Wu, Sen
Monitoring cracks to check the integrity of engineering materials by Non- Destructive Testing (NDT) in industry is significant in industry. And within the NDT techniques, Laser-Generated Surface Acoustic Wave technique (LSAW) has shown to be a promising technique. To further develop non-contact and accurate testing strengths of this method, models for analyzing the generation, propagation and tracking of surface acoustic waves (SAW’s) changes in S45C steel samples with distributed cracks are developed by using Finite Element Method (FEM). Time and frequency domain analyses are used to process the acoustic wave signals after the interaction with cracks. The simulation results and preliminary analyses reveal the good potential LSAW’s have to monitor cracks. First results in developing an experimental setup for crack detection are also provided.
Mechanical Design and Fluid Analysis of a Vertical-Axis Wind Turbine "tribine"
(MEF Üniversitesi, 2018) Dorantes-Gonzalez, Dante Jorge; Khavidaki, Ehsan Layegh
Purpose of the final project is to design a wind turbine with an artistic view, choose proper wind turbine axis and comparison of them. The chosen wind turbine should be manufacturable, eco friendly and innovative. After the wind turbine blade selection, flow simulations were done by Solidworks.
Mef Üniversitesi Mühendislik Fakültesi, Makine Mühendisliği Bölüm Başkanı Prof. Dr. Can Fuat Delale ile Röportaj
(Moment Expo Dergisi, 2016) Delale, Can Fuat
“Amacımız Fark Yaratacak Makine Mühendisleri Yetiştirmek” Gelişen teknolojiye ayak uydurabilen, teknik bilgi ve becerilere sahip fark yaratacak lider makine mühendisleri yetiştirmek üzere yola çıktıklarını belirten MEF Üniversitesi Makine Mühendisliği Bölüm Başkanı Prof. Dr. Can Fuat Delale, eğitim ve öğretimde kullandıkları “Flipped Classroom” (ters yüz edilmiş sınıf) yöntemiyle öğrencilerin; önceden hazırlanmış kısa süreli videoları online izleyip, gerekli diğer gereçleri de kullanarak derslere hazırlıklı geldiğini, ders esnasında da üç ya da dört kişilik gruplar halinde öğretim üyesinin yardımıyla etkileşerek öğrenme ve uygulama süreçlerini daha sağlıklı gerçekleştirebildiklerinin altını çiziyor. Prof. Dr. Can Fuat Delale, bölümün yapısı, sunduğu eğitim olanakları ve sanayi kuruluşlarıyla birlikte yürütülen projelerle ilgili Moment Expo Dergisi’nin sorularını yanıtladı.

Browse

Browsing Makine Mühendisliği Bölümü Koleksiyonu by Scopus Q "N/A"