Makine Mühendisliği Bölümü

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Citation Count: Saltık, S.; Esen Ziya; Dericioğlu, Arcan F. (2023). "A Comparative Study of Effects of Additive Particle Size and Content on Wetting Behavior and Brazing Performance of C/SiC Composite". Journal Of Materıals Engineering And Performance, Vol. 32, No. 13, pp. 5946-5955.
A Comparative Study of Effects of Additive Particle Size and Content on Wetting Behavior and Brazing Performance of C/SiC Composite
(2023) Saltık, Simge; Esen, Ziya; Dericioğlu, Arcan F.; 52373
This study has focused on the influence of size and content of SiC particle incorporation on the wetting behavior of the Ticusil brazing filler alloy and on its brazing performance in C/SiC composite/Ti6Al4V alloy joints. The effect of the size and content of additive SiC particles on the variation of molten brazing filler alloy contact angle was recorded at various brazing time and temperatures. Moreover, the microstructural evolution and mechanical properties of the additive containing C/SiC composite/Ti6Al4V alloy joints produced by the brazing method were investigated. The contact angles in both brazing filler alloys containing nano- and micro-sized SiC particles exhibited a sudden decrease with time during isothermal holding as observed in as-received brazing filler alloys. As the quantity of the SiC particles increased in the brazing alloy, the recorded contact angle values including the final, stable contact angle increased, while the time for the drastic contact angle change also increased remarkably. Compared to as-received counterparts, the addition of 2 wt.% nano-sized SiC and 1 wt.% micro-sized SiC particles improved the shear strength of the joints by 35 and 8%, respectively. Although the recorded contact angle values were close to each other in brazing alloys containing SiC particles with different sizes (37 and 42 degrees for 1 wt.% micro-sized and 2 wt.% nano-sized additions), higher increment was achieved in the mechanical performance of the joints with nano-sized SiC additive due to more homogeneous reinforcement effect of the nanoparticles. The results indicated that the optimum brazing filler alloy contact angle for the highest shear strength is similar to 40 degrees for both nano- and micron-sized additive containing Ticusil filler alloy.
Citation Count: Koçak, Eyüp; Aylı, Ece; Türkoğlu, Haşmet (2022). "A Comparative Study of Multiple Regression and Machine Learning Techniques for Prediction of Nanofluid Heat Transfer", JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS, Vol. 14, No. 6.
A Comparative Study of Multiple Regression and Machine Learning Techniques for Prediction of Nanofluid Heat Transfer
(2022) Koçak, Eyüp; Aylı, Ece; Türkoğlu, Haşmet; 283455; 265836; 12941
The aim of this article is to introduce and discuss prediction power of the multiple regression technique, artificial neural network (ANN), and adaptive neuro-fuzzy interface system (ANFIS) methods for predicting the forced convection heat transfer characteristics of a turbulent nanofluid flow in a pipe. Water and Al2O3 mixture is used as the nanofluid. Utilizing fluent software, numerical computations were performed with volume fraction ranging between 0.3% and 5%, particle diameter ranging between 20 and 140 nm, and Reynolds number ranging between 7000 and 21,000. Based on the computationally obtained results, a correlation is developed for the Nusselt number using the multiple regression method. Also, based on the computational fluid dynamics results, different ANN architectures with different number of neurons in the hidden layers and several training algorithms (Levenberg-Marquardt, Bayesian regularization, scaled conjugate gradient) are tested to find the best ANN architecture. In addition, ANFIS is also used to predict the Nusselt number. In the ANFIS, number of clusters, exponential factor, and membership function (MF) type are optimized. The results obtained from multiple regression correlation, ANN, and ANFIS were compared. According to the obtained results, ANFIS is a powerful tool with a R-2 of 0.9987 for predictions.
Citation Count: Yıldırım, Ender; Özgür, E.; Külah, H.; "A Droplet Based Multi-Drug Screening System Controlled With Electrostatic Microvalves", Proceedings of the 16th International Conference On Miniaturized Systems for Chemistry and Life Sciences, Microtas 2012, pp. 959-961, (2012).
A Droplet Based Multi-Drug Screening System Controlled With Electrostatic Microvalves
(Chemical and Biological Microsystems Society, 2012) Yıldırım, Ender; Özgür, E.; Kulah, Haluk; 31835
This paper presents a droplet-based drug effect analysis system utilizing electrostatically-actuated normallyclosed microvalves to screen the effect of multiple drugs on a single type of cell. Proposed system minimizes the need for off-chip equipment by utilizing parylene based electrostatic microvalves. Prototypes of the system were fabricated and tested using colored DI water and 3 μm diameter micro beads, emulating drugs and cells respectively. During the tests, micro beads could be successfully entrapped in 137 pl droplets. Tests carried out with yeast cells also yielded successful encapsulation of the cells. It was shown that, switching between the drugs could be achieved by applying 200 V dc to operate the microvalves.
Citation Count: Cakmak, Cumhur; Schmidt, Ece Guran; Schmidt, Klaus Werner, "A fast and optimal static segment scheduling method for FlexRay v3.0", 2017 25th Signal Processing And Communications Applications Conference (SIU), (2017).
A fast and optimal static segment scheduling method for FlexRay v3.0
(IEEE, 2017) Çakmak, Cumhur; Schmidt, Ece Güran; Schmidt, Klaus Werner
We propose a novel and fast frame scheduling method for the Static Segment (SS) of the new in-vehicle network standard FlexRay v3.0 in this paper. The proposed methods assigns frames to the SS using the minimum number of time slots based on an Integer Linear Programming formulation. Different. from the existing method in the literature, the proposed method computes optimal frame schedules within miliseconds.
Citation Count: Yegül, M.F., Agpak, K., Yavuz, M. (2010). A new algorithm for u-shaped two-sided assembly line balancing. Transaction of the Canadian Society For Mechanical Engineering, 34(2), 225-241.
A new algorithm for u-shaped two-sided assembly line balancing
(CSME Trans, 2010) Yegül, Mustafa Fatih; Agpak, Kürşat; Yavuz, Mustafa
This study introduces a new hybrid design for a specific case-of assembly lines, and proposes a multi-pass random assignment algorithm to find the minimum number of stations required. The algorithm also finds the sequence and the schedule of the tasks assigned. The new design is a combination of two-sided lines and U-shaped lines, which benefits from the advantages of both designs at the same time. One side of the line is arranged in U-shape allowing stations with crossovers, and the other side of the line is balanced like a traditional straight flow. Depending on product direction, either Left or Right side of the line can be designed in U-shape. Small and large-sized two-sided assembly line test-bed problems were solved using the algorithm. Optimal results are achieved for all small-sized problems. Due to the novelty Of the design, results of large-sized problems are compared to findings of studies on simple two-sided balancing. Algorithm produced better results in most of the cases
Citation Count: Eıldırım, E., Arıkan, M.A.S., Külah, H. (2012). A normally closed electrostatic parylene microvalve for micro total analysis systems. Sensors And Actuators A-Physical, 181, 81-86. http://dx.doi.org/10.1016/j.sna.2012.05.008
A normally closed electrostatic parylene microvalve for micro total analysis systems
(Elsevier Science SA, 2012) Yıldırım, Ender; Arıkan, M. A. Sahir; Kulah, Haluk; 120121
This paper presents an electrostatically actuated, normally closed microvalve for parylene microfluidics. The proposed valve structure isolates the fluid from the electric field, and hence results in relatively low actuation potentials (<60 V) irrespective of the working fluid. Hereby, the microvalve solves electrolysis or electrode shielding problems observed in electrostatic actuation in micro total analysis systems. To investigate leakage properties, microvalves were tested under pressurized flow with de-ionized (DI) water. No detectable leakage ratio was observed up to 20 kPa inlet pressure, due to the unique semicircular valve seat design. It was shown that the valve seat could be reconfigured to enable sealing at various pressure levels for different applications.
Citation Count: Kaak, Abdul Rahman Sabra...et al. (2024). "A novel CFD-ANN approach for plunger valve optimization: Cost-effective performance enhancement", Flow Measurement and Instrumentation, Vol. 97.
A novel CFD-ANN approach for plunger valve optimization: Cost-effective performance enhancement
(2024) Kaak, Abdul Rahman Sabra; Çelebioğlu, Kutay; Bozkuş, Zafer; Ulucak, Oğuzhan; Aylı, Ece; 265836
This paper introduces a novel computational fluid dynamics-artificial neural network (CFD-ANN) approach that has been devised to enhance the efficiency of plunger valves. The primary emphasis of this research is to achieve an optimal equilibrium between hydraulic flow and geometric configuration. This study is a novel contribution to the field as it explores the flow dynamics of plunger valves using Computational Fluid Dynamics (CFD) and proposes a unique methodology by incorporating Machine Learning (ML) for performance forecasting. An artificial neural network (ANN) architecture was developed using a thorough comprehension of flow physics and the impact of geometric parameters acquired through computational fluid dynamics (CFD). Using optimization, the primary aspects of the Artificial Neural Network (ANN), including the learning algorithm and the number of hidden layers, have been modified. This refinement has resulted in the development of an architecture exhibiting a remarkably high R2 value of 0.987. This architectural design was employed to optimize the plunger valve. By utilizing Artificial Neural Networks (ANN), a comprehensive analysis comprising 1000 distinct configurations was effectively performed, resulting in a significant reduction in time expenditure compared to relying on Computational Fluid Dynamics (CFD). The result was a refined arrangement that achieved maximum head loss, subsequently verified using computational fluid dynamics (CFD) simulations, resulting in a minimal discrepancy of 2.66%. The efficacy of artificial neural networks (ANN) becomes apparent due to their notable cost-efficiency, along with their capacity to produce outcomes that are arduous and expensive to get through conventional optimization research utilizing computational fluid dynamics (CFD).
Citation Count: Hatipoğlu, U., Çetin, B., Yıldırım, E. (2018). A novel zero-dead-volume sample loading interface for microfluidic devices: flexible hydraulic reservoir (FHR). Journal Of Micromechanics And Microengineering, 28(9). http://dx.doi.org/ 10.1088/1361-6439/aac333
A novel zero-dead-volume sample loading interface for microfluidic devices: flexible hydraulic reservoir (FHR)
(IOP Publishing LTD, 2018) Hatipoğlu, Utku; Çetin, Barbaros; Yıldırım, Ender; 158278; 31835
Infusing minute amounts of valuable liquids such as samples to microfluidic chips by using common pumping schemes such as syringe pumps often result in an excessive dead-volume. We present a simple yet effective sample loading interface, which helps by pumping the sample to the chip by using the hydraulic pressure generated by the syringe pump. Results show that sample volumes as low as 25 mu l can be delivered at flow rates ranging between 10-30 mu l min(-1). Maximum dead volume ratio was observed to be 3% when infusing 200 mu l of sample at 10 mu l min(-1).
A Reconfigurable Microfluidic Transmitarray Unit Cell
(IEEE, 2013) Erdil, Emre; Topallı, Kağan; Zorlu, Özge; Toral, Taylan; Yıldırım, Ender; Kulah, Haluk; Aydın Çivi, Özlem; 31835)
This paper presents a novel microfluidics based approach to develop a reconfigurable circularly polarized transmitarray unit cell. The unit cell comprises double layer nested split ring slots formed as microfluidic channels that can be filled by fluids. Split regions in the slots are realized by injecting liquid metal into the channels. Beam steering is obtained by implementing rotational phase shifting via manipulating the liquid metal in the slots. X-band unit cell prototypes are fabricated on glass substrate carrying a patterned metal film, and the slot channels are formed by Polydimethylsiloxane (PDMS) using soft lithography techniques.
Citation Count: Yilmaz, E.; Yavuz, S.,"A Simple Way for Estimating Mechanical Properties From Stress-Strain Diagram Using Matlab and Mathematica", 3Rd International Symposium on Multidisciplinary Studies and Innovative Technologies, Ismsıt 2019 - Proceedings, (2012).
A Simple Way for Estimating Mechanical Properties From Stress-Strain Diagram Using Matlab and Mathematica
(Institute of Electrical and Electronics Engineers Inc., 2019) Yılmaz, Emre; Yavuz, Samet; 237938
In this paper, mechanical properties of materials, e.g. ultimate tensile strength, yield stress, elastic modulus, ductility, resilience, toughness, etc., are calculated using MATLAB and Mathematica programming language and stress-strain data of any alloy.
Citation Count: Mahmoud, A.K...et al. "A Study of the Structural and Mechanical Characterization of Hybrid Nanocomposite Material", Materials Science Forum, Vol. 909, pp. 111-115, (2017).
A Study of the Structural and Mechanical Characterization of Hybrid Nanocomposite Material
(Trans Tech Publications LTD, 2017) Mahmoud, A. K.; Al-Nassar, S. I.; Demiral, Murat; Kadhim, H. M.
This work is devoted on the synthesized new hybrid nanocomposite materials by using mechanical stirring method through a combination of different types of material; epoxy based matrix and nanofiller (TiO2 nanoparticles) as a reinforcement material. In additional this paper studies the effect of TiO2 nanoparticles with percentage 2-8 wt% added to epoxy based matrix on the mechanical properties (tensile properties and hardness property). The results showed that the tensile strength of nanocomposite material increased gradually by increasing the weight percentage of TiO2 nanoparticles from 2 wt % to 8 wt % TiO2, while the best tensile strength was at 8 wt % TiO2. The maximum value of tensile strength was 270% higher than the neat epoxy matrix. The hardness increase gradually with increasing percentage of TiO2 nanoparticles from 2wt% TiO2 up to 8wt% TiO2, the maximum value of hardness was at 8wt % TiO2, so the hardness of nanocomposite is around 86% higher than the neat epoxy matrix
Citation Count: Akar, Samet; Seyedzavvar, Mirsadegh; Boğa, Cem. (2023)." A study on the μwire-EDM of Ni55.8Ti shape memory superalloy: an experimental investigation and a hybrid ANN/PSO approach for optimization", Journal Of The Brazilian Society Of Mechanical Sciences And Engineering, Vol.45, No.3.
A study on the μwire-EDM of Ni55.8Ti shape memory superalloy: an experimental investigation and a hybrid ANN/PSO approach for optimization
(2023) Akar, Samet; Seyedzavvar, Mirsadegh; Boğa, Cem; 315516
The unique properties of high hardness, toughness, strain hardening, and development of strain-induced martensite of nickel-titanium superalloys made the micro-wire electro discharge machining (mu wire-EDM) process one of the main practical options to cut such alloys in micro-scale. This paper presents the results of a comprehensive study to address the response variables of Ni55.8Ti superalloy in mu wire-EDM process, including the kerf width (KW), material removal rate (MRR), arithmetic mean surface roughness (R-a) and white layer thickness (WLT). To this aim, the effects of pulse on-time (T-on), pulse off-time (T-off), discharge current (I-d) and servo voltage (SV) as input parameters were investigated using the experiments conducted based on Taguchi L-27 orthogonal array. The results were employed in the analysis of variance (ANOVA) to examine the significance of input parameters and their interactions with the output variables. An optimization approach was adopted based on a hybrid neural network/particle swarm optimization (ANN/PSO) technique. The ANN was employed to achieve the models representing the correlation between the input parameters and output variables of the mu wire-EDM process. The weight and bias factor matrices were obtained by ANN in MATLAB and together with the feed forward/backpropagation model and developed functions based on PSO methodology were used to optimize the input parameters to achieve the minimum quantities of KW, R-a and WLT and the maximum value of MRR, individually and in an accumulative approach. The results represented a maximum accumulative error of nearly 8% that indicated the precision of the developed model and the reliability of the optimization approach. At the optimized level of input parameters obtained through the accumulative optimization approach, the KW, R-a, and WLT remained nearly intact as compared with the levels of responses obtained in the individual optimization approach, while there was a sacrifice in the machining efficiency and reduction in the MRR in the mu wire-EDM process of Nitinol superalloy.
Citation Count: Özdemir, M., İder, S.K. (2016). A switching inverse dynamics controller for parallel manipulators around drive singular configurations. Turkish Journal Of Electrical Engineering And Computer Sciences, 24(5), 4267-4283. http://dx.doi.org/10.3906/elk-1502-50
A switching inverse dynamics controller for parallel manipulators around drive singular configurations
(TUBİTAK Scientific&Technical Research Council Turkey, 2016) Özdemir, Mustafa; İder, Sıtkı Kemal; 108608
Despite many advantages, parallel manipulators are known to possess drive singularities where the control of one or more degrees of freedom is lost. Around these singular configurations, the required actuator forces grow unbounded. Previous efforts in the literature put forward singularity-consistent trajectory planning and singularity robust modification of the dynamic equations as a solution to this problem. However, this previous method is applicable only for the open-loop operation of the manipulator, whereas initial configuration errors, external disturbances, and modeling errors should necessarily be taken into account in a closed-loop sense in real-life applications. With this aim, a switching inverse dynamics controller is proposed in this study for the trajectory tracking control of parallel manipulators as they pass through drive singular configurations. Simulations of the application of the developed controller result in good tracking performance, even in the presence of modeling errors, while the actuator efforts remain bounded and continuous in the neighborhood of the singularity
Citation Count: Yildirim, E.; Kulah, H.; Arikan, M.A.S.,"An Electrostatically Actuated Parylene Microvalve for Lab-On-A-Chip Applications", 2011 16th International Solid-State Sensors, Actuators and Microsystems Conference, Transducers'11, pp. 250-253, (2011).
An Electrostatically Actuated Parylene Microvalve for Lab-On-A-Chip Applications
(2011) Yıldırım, Ender; Arıkan, M. A. Sahir; Kulah, Haluk; 31835
This paper presents a novel electrostatic microvalve to control in-plane flow on parylene based lab-on-a-chip-devices. Normally-closed design of the microvalve insulates the working fluid from the electric field, while providing low leakage up to 40 kPa inlet pressure. Prototypes are fabricated and tested for pull-in and flow characterization. Pull-in voltage is measured to be 150 V independent of the working fluid. No leakage is detected up to 20 kPa inlet pressure.
Citation Count: Yaman, K., Çoğun, C. (2014). An experimental work on using conductive powder-filled polymer composite cast material as tool electrode in EDM. International Journal of Advanced Manufacturing Technology, 73(1-4), 535-543. http://dx.doi.org/10.1007/s00170-014-5839-y
An experimental work on using conductive powder-filled polymer composite cast material as tool electrode in EDM
(Springer London Ltd, 2014) Yaman, Kemal; Çoğun, Can; 3837
This paper introduces the composite tool electrodes made of electrical conductive powder-filled polyester resin matrix material, providing promise for the electrical discharge machining (EDM) process. The dendrite-shaped copper powder, graphite powder, and their mixture were used as conductive fillers. Six different types of composite electrodes, namely, plain copper-polyester, pressed copper-polyester, furnaced copper-polyester, plain copper-graphite-polyester, pressed copper-graphite-polyester, and furnaced copper-graphite-polyester were prepared. It is found experimentally that increasing v (f) improved workpiece material removal rate, tool wear rate, relative wear, and electrical conductivity of electrodes. The pressed copper-polyester electrodes were found to be promising in the ED finishing of workpieces at low machining current settings. The practical applicability of the proposed composite electrodes in the industry was also illustrated
Citation Count: Akyürek, T. (2022). "Analyses of plate perforation for various penetrator-target plate combinations", Journal of Mechanical Science and Technology, Vol.36, No.4, pp.1749-1760.
Analyses of plate perforation for various penetrator-target plate combinations
(2022) Akyürek, Turgut
In this study, kinetics and kinematics of perforation process for various penetrator-target plate combinations is analyzed, a methodology in a flow chart format to decide on failure mode, and for each failure mode, an appropriate combined analytical model that requires only common test data is proposed. The proposed methodology and analytical models that are recommended for the related failure mode are assessed by using a huge amount of test data from the literature. The penetrator-target plate configurations cover the penetrators with ogive, conical, hemi-spherical and blunt noses, at different plate thicknesses, and plate thickness to penetrator diameter ratios, made of different metallic materials. Analyzed failure modes include ductile hole enlargement, plugging, dishing, and petal forming. Assessment is done for impact velocities ranging between 215–863 m/s. The estimations based on the proposed flow chart and recommended failure models are in good agreement with the related test data and numerical analysis results.
Citation Count: Yıldırım, E., Külah, H. (2011). Analysis and characterization of an electrostatically actuated in-plane parylene microvalve. Journal of Micromechanics and Microengineering, 21(10). http://dx.doi.org/10.1088/0960-1317/21/10/105009
Analysis and characterization of an electrostatically actuated in-plane parylene microvalve
(IOP Publishing LTD, 2011) Yıldırım, Ender; Kulah, Haluk; 31835; 120121
This paper presents analysis and implementation of a simple electrostatic microvalve designed for use in parylene-based lab-on-a-chip devices. The microvalve utilizes an in-plane collapsing diaphragm. To investigate the pull-in behavior of the diaphragm and flow characteristics, a thorough analysis is carried out using the finite element method. Microvalves with different diaphragm radii are fabricated using surface micromachining techniques. Pull-in tests are carried out under the no-flow condition with air, oil and water as the working fluid. Test results show that the pull-in occurs around 20 V for 450 mu m radius diaphragms with oil and air. However, it is not possible to observe pull-in up to 100 V (both ac and dc) for the case of water as the working fluid, due to its relatively high dielectric constant and conductivity. The flow tests show that no leakage flow was observed up to 4 kPa inlet pressure under 85 V actuation potential. The leakage ratio becomes 17% at 10 kPa inlet pressure. It is observed that the leakage can be reduced controllably by increasing the actuation potential, enabling the precise control of the flow rate
Citation Count: Akyurek, Turgut, "Analysis and simplified modelling of simulation of tests for medium-duty truck collision with twin anti-ram bollards", International Journal of Crashworthiness, (2019).
Analysis and simplified modelling of simulation of tests for medium-duty truck collision with twin anti-ram bollards
(Taylor&Francis LTD, 2019) Akyürek, Turgut; 48511
An actual test of medium-duty truck collision with twin anti-ram bollards of steel tube is analysed and simulated with different mass-spring-damper models to study bollard design requirements. Test data is obtained from test report of a medium-duty truck crashed into two fixed twin bollards at speed 78.3 km/h. Maximum impact load and impact height at that time is important in the analysis. Bollard height should be close to or larger than the vehicle's centre of gravity height to avoid climbing of the truck on the bollard. However, increasing impact height yields also increase in failure risk of bollard. Foundation is also critical in success of the bollard in successfully stopping the vehicle. The bollard should be fixed to the frame embedded in the concrete foundation so that the deformation in concrete be minimised. The bollard should be so stiff to stop the vehicle while most of the impact energy is absorbed by the vehicle through deformation of its frontal sections. A single-degree freedom linear mass-spring-damper model is the simplest model, but its results are not in line with test data. Single-degree non-linear model simulates the peak load but not the load history. However, using engine mass instead of truck mass in the single-degree model provides acceptable impact force data for the bollard. Two-degree freedom mass-spring damper linear model seems to simulate both truck's and bollard's deformation in a good manner. Non-linear analysis simulates the collision in a more realistic way, but it requires more data to be determined with testing.
Citation Count: Türkoğlu, Haşmet. "Analysis and simplified modelling of simulation of tests for mediumduty truck collision with twin antiram bollards", Trabzon: 5 th International Anatolian Energy Symposium.
Analysis and simplified modelling of simulation of tests for mediumduty truck collision with twin antiram bollards
(2020) Türkoğlu, Haşmet; 12941
Citation Count: Yıldırım, E. (2017). Analysis and testing of a contraction-and-expansion micromixer for micromilled microfluidics. Microsystem Technologies-Micro-And Nanosystems-Information Storage And Processing Systems, 23(10), 4797-4804. http://dx.doi.org/10.1007/s00542-017-3291-2
Analysis and testing of a contraction-and-expansion micromixer for micromilled microfluidics
(Springer, 2017) Yıldırım, Ender; 31835
In this paper, numerical analysis and experimental investigation of a micromixer, which was specifically designed for microfluidic devices fabricated by micromilling, is presented. The mixer is composed of series of contractions and expansions in zigzag arrangement along a mixing channel. Mixers, fabricated by micromilling on polymethylmethacrylate (PMMA), were tested with %0.1 Ponceau 4R red food dye solution and distilled water. According to experiment results, over 70% mixing efficiency could be obtained for the flows with Reynolds number (Re) greater than 40. It was also numerically shown that by increasing the number of successive contractions and expansions, it could be possible to achieve over 80% mixing efficiency when Re = 55 for the species with diffusion coefficient of 5 x 10(-9) m(2)/s. Although the micromixer was specifically designed for micromilling, it is expected that the mixer can be useful in any microfluidic device fabricated by any other technique.

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