Makine Mühendisliği Bölümü Koleksiyonu

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

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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.
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 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.
Citation - WoS: 27
Citation - Scopus: 33
Acoustic and Mechanical Properties of Luffa Fiber-Reinforced Biocomposites
(Elsevier, 2019) Genç, Garip; Körük, Hasan
This chapter presents an overview of acoustic and mechanical behaviors of luffa fiber reinforced biocomposites. A growing number of studies are examining the composites of biodegradable fibers such as flax, hemp, kenaf and luffa due to the adverse effects of chemical materials on nature. The low cost and superior acoustic and acceptable mechanical properties of biocomposites make them very attractive for practical applications such as sound and vibration isolation. However, the acoustic and mechanical characteristics of biocomposites and their dynamic behaviors should be fully determined before considering them for practical applications. In this chapter, acoustic properties, such as sound absorption and transmission loss, and mechanical properties, such as damping and elasticity of luffa fiber reinforced composites, are presented. The variations in acoustic and mechanical properties due to different samples and manufacturing process are explored.
Advances on Laser-Generated Surface Acoustic Wave-Based Characterization of Thin Films and Skin Tissues
(2016) Dorantes-Gonzalez, Dante Jorge
...
Citation - WoS: 6
Citation - Scopus: 6
Computational Alloy Design, Synthesis, and Characterization of Wmonbvcrx Refractory High Entropy Alloy Prepared by Vacuum Arc Melting
(Elsevier Ltd, 2024) Alkraidi, A.B.N.; Mansoor, M.; Boztemur, B.; Gökçe, H.; Kaya, F.; Yıldırım, C.; Öveçoğlu, M.L.
Prior investigations have demonstrated enhanced mechanical properties, such as hardness and wear resistance, through high-entropy alloy designs that contain refractory metals. We propose the WMoNbVCrx alloy phase space as a single-phase BCC-structured, hard, and refractory high-entropy alloy for the first time. The WMoNbVCrx alloy (x = 0, 0.25, 0.5, 0.75, and 1) system is investigated computationally through CALPHAD and DFT for the equimolar and non-equimolar compositional phase spaces and synthesized through vacuum arc melting. The DFT calculations demonstrated the excellence of specific non-equimolar compositional spaces. It was found that stoichiometries rich in W and poor in V are exceptionally hard, while those rich in V and poor in W demonstrate unprecedented toughness, as determined by the ductility descriptor (Pugh's Ratio). The computational analysis shows the significance of microstructures that contain both (W-rich and W-poor) solid solution, where a synergy between hardness and toughness is created. Our experimental synthesis using vacuum arc melting demonstrated the possibility of successfully producing these alloys with W-rich (dendritic) and W-poor (interdendritic) solid solution regions, starting from elemental powders. The introduction of chromium (Cr) resulted in enhanced microhardness and wear resistance. The peak microhardness was attained when 0.5 moles of Cr were added, reaching 7.03 ±0.24 GPa, accompanied by the least wear volume loss. The produced alloys were found to align with the computationally predicted-designed alloys in terms of the hardness and Young's modulus trends that they follow. This comprehensive investigation underscores the synergistic application of CALPHAD and DFT techniques in the tailored design of novel high-entropy alloys, explaining their synthesis, structural correspondence, and the pivotal role of Cr in enhancing the mechanical properties of these alloys. © 2024 Elsevier B.V.
Citation - WoS: 38
Citation - Scopus: 38
Development of a Multigenerational Energy System for Clean Hydrogen Generation
(Elsevier Ltd, 2021) Dinçer, İbrahim; Karapekmez, Aras
The existing fueling options for many power plants are still dependent primarily on fossil fuel resources, which in return cause serious local and global environmental problems. Therefore, in order to reduce the detrimental effects of greenhouse gas emissions, the use of cleaner production methods has been accelerated to develop and implement environmentally- friendly energy systems. In this regard, the combination of renewable energy systems and hydrogen production methods will definitely play a crucial role in the energy sector’s transition to a carbon-free production. In order to make the use of geothermal energy cleaner and more sustainable, some obstacles need to be eliminated. Most importantly, the hydrogen sulfide emissions may cause serious concerns in public acceptance of geothermal power plants. In the current study, solar, wind and geothermal energy resources are integrated to develop an integrated renewable-based energy system with a key objective of higher environmental and system performance. The underlying motivation is to propose a model which consists of a hydrogen sulfide abatement unit and an electrolyzer to produce hydrogen from hydrogen sulfide and hence eliminites the hydrogen sulfide emissions. A detailed thermodynamic analysis is carried out using Engineering Equation solver (EES) software. In addition, the effects of key design parameters and operating conditions (such as wind inlet speed and average hourly solar radiation) are analyzed, and their effects on the system overall performance are investigated. When 60 kg/s of geothermal fluid is supplied to the designed system, assuming that the NCG composition is equal to 15%, 0.7388 kg hydrogen sulfide will be emitted and 0.0433 kg hydrogen will be produced per second. The first-law (energy) and second-law (exergy) efficiencies are found to be 52.97% and 55.69% respectively.
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: 31
Citation - Scopus: 34
Development of a New Solar, Gasification and Fuel Cell Based Integrated Plant
(Elsevier, 2021) Dinçer, İbrahim; Karapekmez, Aras
Despite its shortcomings, fossil-based fuels are still utilized as the main energy source, accounting for about 80% of the world's total energy supply with about one-third of which comes from coal. However, conventional coal-fired power plants emit relatively higher amounts of greenhouse gases, and the derivatives of air pollutants, which necessitates the integration of environmentally benign technologies into the conventional power plants. In the current study, a H2–CO synthesis gas fueled solid oxide fuel cell (SOFC) is integrated to the coal-fired combined cycle along with a concentrated solar energy system for the purpose of promoting the cleaner energy applications in the fossil fuel-based power plants. The underlying motivation of the present study is to propose a novel design for a conventional coal-fired combined cycle without altering its main infrastructure to make its environmentally hazardous nature more ecofriendly. The proposed SOFC integrated coal-fired combined cycle is modeled thermodynamically for different types of coals, namely pet coke, Powder River Basin (PRB) coal, lignite and anthracite using the Engineering Equation Solver (EES) and the Ebsilon software packages. The current results show that the designed hybrid energy system provide higher performance with higher energy and exergy efficiencies ranging from 70.6% to 72.7% energetically and from 35.5% to 43.8% exergetically. In addition, carbon dioxide emissions are reduced varying between 18.31 kg/s and 30.09 kg/s depending on the selected coal type, under the assumption of 10 kg per second fuel inlet.
Citation - WoS: 8
Citation - Scopus: 10
Development of an Equivalent Shell Finite Element for Modelling Damped Multi-Layered Composite Structures
(Elsevier, 2020) Şanlıtürk, Kenan Y.; Özer, Mehmet Sait; Körük, Hasan
A new equivalent shell finite element (FE) for modelling damped multi-layered structures is presented in this study. The method used for developing the new FE for such structures is based on the idea that the strain energy of the equivalent single-layer FE must be equal to the sum of the strain energies of individual layers. The so-called energy coefficients are defined for this purpose for the extensional, bending and shear deformations of the composite structure. These coefficients are then determined and used as correction multipliers during stacking the elemental matrices of individual layers. Two approaches, based on second-order strain or stress distribution assumption through the composite thickness, are investigated for deriving the shear energy coefficients. The damping capability of the FE developed here originates from using complex Young's modulus to define the material properties of individual layers. The resulting equivalent single-layer shell element with four nodes has six degrees-of-freedom per node. The accuracy, advantages and limitations of the composite FE developed in this work are investigated using experimental as well as theoretical results. In the light of the finding of these investigations, further enhancement in the formulation is made by also utilising a new shear correction factor for the individual layers in the equivalent shell element. Final results for free- and constrained-layered structures confirm that the equivalent shell FE developed here can be used effectively for the prediction of the modal properties of damped multi-layered structures.
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 - Scopus: 3
Effects of Machining on the Acoustic and Mechanical Properties of Jute and Luffa Biocomposites
(Elsevier, 2023) Genç, Garip; Körük, Hasan
After their production, biocomposite structures do not always have the final shape or dimensions required for their purpose, hence, they need machining. However, the effects of machining on the acoustic and mechanical properties of many biocomposites are still not well known. The effects of machining on the acoustic and mechanical properties of jute and luffa biocomposites are revealed in this chapter. To do this, the sound absorption coefficients (or SACs) and transmission losses (or TLs) of jute and epoxy and luffa and epoxy composite samples, with and without a turning process, are determined using the impedance tube method. The loss factors and Young’s moduli of the jute and epoxy and luffa and epoxy composite samples, with and without a milling process, are identified using experimental and theoretical modal analyses. The results show that, when the samples are machined, the sound absorption coefficients reduce by 3%-7%, the transmission loss levels increase by 6-11dB, and the damping levels and Young’s moduli reduce by 0.1%-0.5% and 3%-4%, respectively. © 2023 Elsevier Ltd. All rights reserved.
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.
Citation - WoS: 7
Citation - Scopus: 9
Identification of the Viscoelastic Properties of Soft Materials Using a Convenient Dynamic Indentation System and Procedure
(Elsevier, 2022) Körük, Hasan,; Beşli, Ayça,; Koç, Ömer Hayati,; Yurdaer, Berk Salih,
The responses of soft structures such as tissue depend on their viscoelastic properties. Therefore, the knowledge of the elastic and damping properties of soft materials is of great interest. This paper presents the identification of the viscoelastic properties of soft materials using a convenient dynamic indentation system and procedure. Using an electromagnet, a force is applied to a rigid sphere located at the soft-material interface and the dynamic response of the sphere is recorded using a high-speed camera. The recorded video is processed to identify the displacement of the sphere as a function of time. The dynamic response of the sphere located at the soft-material interface is predicted using an analytical model that considers the shear modulus and density of the soft sample, the radiation damping due to shear waves, and the radius and density of the sphere. By matching the measured and predicted steady-state displacements of the sphere, the shear modulus of the soft sample is determined. The viscous damping ratio of the soft sample is identified by using an equivalent viscous damping ratio for the soft sample in the analytical model and matching the measured and predicted oscillation amplitudes of the sphere. Experiments and analyzes are performed using gelation phantoms with different mechanical properties, spheres of different materials and sizes, and different force levels to verify the system and procedure. Three experiments are performed for each gelation phantom, sphere, and external force, and the repeatability of the results is presented. The results show that the dynamic indentation system and procedure presented in this study can be conveniently used to determine the viscoelastic properties of soft materials in practical applications.
Citation - Scopus: 4
Jute and Luffa Fibers: Physical, Acoustical, and Mechanical Properties
(Elsevier, 2022) Yüce, Hüseyin; Genç, Garip; Körük, Hasan
In this study, the physical, acoustical, and mechanical properties of jute and luffa fibers are presented. It should be noted that, although the main materials of jute and luffa fibers are cellulose, hemicellulose, and lignin, the mechanical properties of jute and luffa fibers and the acoustical properties of jute and fiber samples can be quite different. It is worth noting that jute fibers are bidirectional while luffa fibers are random-oriented. Furthermore, the diameters and lengths of these two fibers can be quite different. One problem with these natural fibers is that very different values for their diameter, length, and density have been reported in the literature. Therefore, the diameter, length, and density of a huge number of jute and luffa fibers were measured using precise equipment to determine their average values and deviations in this study. In addition to the results of these measurements, the results of a comprehensive literature review on the physical, acoustical, and mechanical properties of jute and fibers and their green samples (i.e., fiber samples without any resin) were presented in this study. © 2023 Elsevier Ltd. All rights reserved.
Kabarcık Dinamiği için Gaz Basıncı Yasası
(2015) Delale, Can Fuat; Pasinlioglu, Şenay
...
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.
Nbmovta Refractory High-Entropy Alloy Incorporated Wni Matrix Composite as a Future Plasma-Facing Material: Evaluation of Mechanical Properties and Helium Ion Irradiation Behavior
(Elsevier Sci Ltd, 2025) Boztemur, Burcak; Filiz, Kaan; Karaguney, Zahide; Gokaydin, Eyupcan; Bozkurt, Yasin; Ozbasmaci, Ceren; Ovecoglu, M. Lutfi
Refractory high-entropy alloys (RHEAs) have gained attention in the last decades with their high mechanical strength, self-healing mechanism, and high irradiation resistance. These materials are evaluated to have a high potential as plasma-facing materials for fusion reactors. In this study, helium ion irradiation and mechanical behaviors of the RHEA-reinforced WNi matrix composites were investigated based on this perspective. Equimolar molybdenum, niobium, tantalum and vanadium powders were mechanically alloyed for 6 h to produce NbMoVTa RHEA with a single BCC phase. Then, different amounts (10, 20, 30, and 40 wt%) of RHEA were added into the W1Ni (containing 99 wt% W and 1 wt% Ni) matrix by planetary ball milling for 72 h. Consolidation was conducted by spark plasma sintering technique (1410 degrees C, 1 min). X-ray diffraction, scanning electron microscopy coupled with energy dispersion spectroscopy, and Archimedes' density analyses were performed on the composites. Moreover, wear and hardness properties of the composites were examined, and the lowest specific wear rate (0.59 mm3/N.m x 10- 5) and the highest hardness value (10.10 GPa) were found for the W1Ni-40RHEA composite. Helium irradiation was exposed to the composites to observe their irradiation resistance. It was observed that the lowest increment and the least deformation were obtained with the SPS'ed W1Ni-40RHEA composite. With the analysis of He+ irradiation, it was determined that the effect of radiation on mechanical properties is irrelevant. Also, it was observed that the addition of RHEA into the W matrix can create a high potential for using plasma-facing material. Moreover, it decreased the problems of tungsten against He+ irradiation.
Citation - WoS: 5
Citation - Scopus: 6
On the Gas Pressure Inside Cavitation Bubbles
(Aip Publishing, 2023) Pasinlioğlu, Şenay; Delale, Can F. F.
The validity of the reduced order [Delale and Pasinlioglu, Acoustic cavitation model based on a novel reduced order gas pressure law, AIP Adv. 11, 115309 (2021)] and of classical polytropic gas pressure laws during the response of a bubble to variations in the pressure of the surrounding liquid is investigated. In particular, from the exact expression of the gas pressure coupled to the thermal behavior of gas bubbles, we identify the conditions where the reduced order gas pressure law and the classical polytropic law hold. We then distinguish three regimes for the change of state of the bubble during its nonlinear oscillations as the nearly isothermal, transition, and nearly adiabatic regimes, depending on the value of the polytropic index, and we determine the mean value of the polytropic index in each regime by averaging over a parameter, which is a function of the Peclet number based on the characteristic thermal diffusion time. The results of the temporal evolution of the bubble radius, the bubble wall temperature, and the partial gas pressure inside the bubble are presented using an acoustic cavitation model based on the reduced order gas pressure law for both constant and variable interface properties.

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