Körük, Hasan
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Körük, Hasan, & Körük,Hasan & Hasan Körük & Körük, Hasan
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korukh@mef.edu.tr
korukh@mef.edu.tr
korukh@mef.edu.tr
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02.03. Department of Mechanical Engineering
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45
Citations
533
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Scholarly Output
40
Articles
30
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10043/69937
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0
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WoS Citation Count
390
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538
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1
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WoS Citations per Publication
9.75
Scopus Citations per Publication
13.45
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29
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0
| Journal | Count |
|---|---|
| Journal of Natural Fibers | 3 |
| Cellulose Fibre Reinforced Composites: Interface Engineering, Processing and Performance | 3 |
| European Journal of Physics | 2 |
| Advances in Bio-Based Fiber: Moving Towards a Green Society | 2 |
| IOP Conference Series: Materials Science and Engineering | 2 |
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40 results
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Article Citation - WoS: 19Citation - Scopus: 26Jute 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 CihanThe 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.Article Citation - WoS: 3Citation - Scopus: 3Characterization of Viscoelastic Materials Using Free-Layered and Sandwiched Samples: Assessment and Recommendations(Polish Physical Society, 2015) Özer, Mehmet Sait; Körük, Hasan; Şanlıtürk, Kenan YüceViscoelastic 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.Article Citation - WoS: 12Citation - Scopus: 14Modelling Small and Large Displacements of a Sphere on an Elastic Half-Space Exposed To a Dynamic Force(IOP Publishing, 2021) Hasan Körük; Koruk, H.Spheres at medium interfaces are encountered in many applications, including in atomic force microscopy or indentation tests. Although the Hertz theory describes the contact mechanics between an elastic sphere and an elastic half-space for static loading and small deformations very well, there is a need to consider the density of the medium, the mass of the sphere and the radiation damping for dynamic loading to obtain reliable results. In this study, an analytical model for predicting the small and large displacements of a sphere on an elastic half-space exposed to a dynamic force is developed. For this purpose, after summarizing a mathematical model that has recently been proposed for the sphere at a medium interface, a finite element model for the sphere at an elastic interface is developed. Based on the comparison of the mathematical and finite element models, an improved analytical model for the sphere at an elastic interface is developed. In addition to considering the elastic properties of the medium and the size of the sphere, the model developed here takes into account the density of the medium, the mass of the sphere, and the radiation damping, and the model is valid for small and large sphere displacements. The developed model can be used to understand the dynamic responses of spherical objects at medium interfaces in practical applications. Furthermore, the proposed model is a remarkable tool for undergraduate and graduate students and researchers in the fields of engineering, materials science and physics to gain insight into the dynamic responses of spheres at medium interfaces. © 2021 European Physical Society.Article Citation - WoS: 25Citation - Scopus: 26Acoustic Particle Palpation for Measuring Tissue Elasticity(American Institute of Physics, 2015) El Ghamrawy, Ahmed; Körük, Hasan; Choi, James J; Pouliopoulos, Antonios NWe propose acoustic particle palpation—the use of sound to press a population of acoustic particles against an interface—as a method for measuring the qualitative and quantitative mechanical properties of materials. We tested the feasibility of this method by emitting ultrasound pulses across a tunnel of an elastic material filled with microbubbles. Ultrasound stimulated the microbubble cloud to move in the direction of wave propagation, press against the distal surface, and cause deformations relevant for elasticity measurements. Shear waves propagated away from the palpation site with a velocity that was used to estimate the material’s Young’s modulus.Article Biyomalzemelerin Akustik ve Mekanik Özelliklerinin Arastırılması(2020) Genç, Garip; Körük,HasanBu 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.Article Citation - WoS: 8Citation - Scopus: 9Identification of Crack Noises in Household Refrigerators(Elsevier, 2015) Körük, Hasan; Arısoy, Ahmet; Bilgin, NecatiThe 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.Conference Object Assessment of the Models for Predicting the Responses of Spherical Objects in Viscoelastic Mediums and at Viscoelastic Interfaces(IOP Publishing Ltd, 2021) Körük, HasanSpherical 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.Conference Object Citation - Scopus: 6On the Difficulties in Manufacturing of Luffa Fibers Reinforced Biocomposites and Variations in Their Dynamic Properties(Institute of Noise Control Engineering, 2016) Genç, Garip; Körük, HasanDefects 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.Article Citation - WoS: 10Citation - Scopus: 20Assessment of the Measurement and Prediction Methods for the Acoustic Properties of Natural Fiber Samples and Evaluation of Their Properties(Taylor & Francis, 2021) Körük, HasanAlthough some studies have been conducted to show how natural fibers canreplace synthetic materials, the use of many natural fibers is still limited. Onthe other hand, the use of natural fibers can become very common in manyapplications once their performance is fully understood. This paper aims topresent a critical assessment of the acoustic properties of natural fibersamples. First, the methods commonly used for the measurement and prediction of the acoustic properties of natural fiber samples are determined.Second, the common techniques for measuring sound absorption coefficients (SACs) and sound transmission losses (STLs) are presented, and theiradvantages and limitations are evaluated. After that, the models commonlyused for the prediction of acoustic properties are presented. Then, the SACsof many natural fiber samples are presented along with the thickness, bulkdensity and flow resistivity of the samples. Furthermore, the SACs of thesamples are normalized using sample thickness and bulk density, and thesound absorption performance of the fiber samples is evaluated. Based onthe results of many natural fiber samples, an empirical model for estimatingthe SACs of natural fiber samples is presented. Finally, the STLs of someporous natural fiber samples are presented.Article Citation - WoS: 69Citation - Scopus: 91Investigation of the Acoustic Properties of Bio Luffa Fiber and Composite Materials(Elsevier, 2015) Genç, Garip; Körük, HasanConsidering the adverse effects of petroleum-based materials on nature, finding and developing new materials as alternatives to these chemical materials become a necessity in practice. On the other hand, these new materials need characterization to be considered and effectively used in practical applications. The acoustic properties of luffa bio fiber and composite materials are investigated in this study. First, the preparation of various luffa test samples and the method for acoustic characterization of the luffa samples is presented. Then, the acoustic absorption properties of both luffa fiber and composite materials are identified using the impedance tube method. After that, the transmission loss levels of the same luffa samples are determined. All the results are evaluated and the acoustic performances of luffa materials are highlighted.