Zeki Kiral - Academia.edu (original) (raw)

Papers by Zeki Kiral

Yapısal cevap kontrol sistemlerinin araştırılması ve geliştirilmesi araştırmacıların önemli bir i... more Yapısal cevap kontrol sistemlerinin araştırılması ve geliştirilmesi araştırmacıların önemli bir ilgi alanıdır. Farklı dinamik yüklerin etkisi altında mühendislik yapılarının titreşim tepkilerini azaltmak için yapısal kontrol sistemlerinin kullanılması bir gereklilik haline gelmiştir. Yapısal cevap kontrolü kavramını uygulanabilir bir teknolojiye dönüştürmek için ciddi çabalar sarf edilmiştir. Farklı çalışma ortamlarında veya operasyonel işlemlerde kullanılan yapıların dinamik davranışlarının iyileştirilmesi için yenilikçi aktif titreşim kontrol sistemlerine ihtiyaç vardır. Bu konuda, hava jet itkileri kullanılarak yapıların titreşimlerini azaltma düşüncesi hala araştırılmaya ve uygulamaya açıktır. Bu çalışmada, örnek bir mühendislik yapısının harmonik zemin zorlaması altında verdiği cevaplar ve hava jet itkileri yardımıyla titreşim kontrolü incelenmiştir. Harmonik zemin zorlaması, yapının en yüksek yer değiştirmeye sahip olduğu birinci doğal frekans civarında verilmiştir. Yapının titreşim kontrolü için, durum geri besleme kontrol yöntemi kullanılmıştır. Örnek yapının titreşim kontrolü için gerekli olan kuvvetler hesaplanmıştır. Ayrıca, Matlab Simscape Multibody yardımıyla hem sistemin fiziksel olarak modellenmesi, hem de oluşan titreşimin görselleştirilmesi sağlanmıştır. Elde edilen sonuçlar karşılaştırılmış ve önerilen sistem ile yapının titreşimlerini sönümlenebileceği sonucuna ulaşılmıştır. Son olarak, kontrol kuvvetlerinin sisteme hava jet itkileri kullanılarak verilmesi için lüle tasarımı yapılmıştır.

Journal of Composite Materials, Sep 3, 2009

This article reports the experimental analysis of free and forced vibrations of a cantilever symm... more This article reports the experimental analysis of free and forced vibrations of a cantilever symmetric laminated composite beam with different lay-up sequences. The free vibrations generated due to initial displacements are recorded by two laser displacement sensors. The damping ratios for different ply orientations are determined by using the ratios between the successive peaks in the free vibration responses and the corresponding envelope curves. The dynamic response of the beam to a moving load with constant velocity is also investigated. The pressured air is blown out onto the beam to create the load and the movement of the load is achieved by an industrial robot manipulator. The moving load mechanism is peculiar to this study. The free and moving load responses are also examined by the finite element method. A commercial finite element package ANSYS® is used for numerical analyses. The results reported in this study show that the lay-up sequence has an important role on the dynamic response of the laminated composites and the velocity of the moving load affects the dynamic response considerably, especially for [90]2s lay-up.

Aircraft Engineering and Aerospace Technology, Jul 31, 2023

Purpose The purpose of this study is to identify the possible relation between the vibration and ... more Purpose The purpose of this study is to identify the possible relation between the vibration and the stall by using the vibration response of the airfoil. For this purpose, the root mean square values of the acceleration signals are evaluated to demonstrate the compatibility between the stall angles and the vibration levels. Design/methodology/approach An experimental study is conducted on NACA 4415 airfoil at Reynolds numbers 69e3, 77e3 and 85e3. Experiments are performed from 0° to 25° of the angles of attack (AoA) for each Reynolds number condition. To observe the change of the vibration values at the stall region clearly, experiments are performed with the AoA ranging from 10° to 25° in 1° increments. Three acceleration sensors are used to obtain the vibration data. Findings The results show that the increase in the amplitude of the vibration is directly related to the decrease in lift. These findings indicate that this approach could be beneficial in detecting stall on airfoil-type structures. Originality/value This study proposes a new approach for detecting stall over the airfoil using the vibration data.

MP MATERIALPRUEFUNG - MP MATERIALS TESTING, Oct 1, 2022

In this study, low velocity single and repeated impact behaviors of 3D printed curved honeycomb c... more In this study, low velocity single and repeated impact behaviors of 3D printed curved honeycomb cellular panels that can be used for impact protection are investigated. The energy absorbing capacity of the 3D printed honeycomb curved panels is predicted by evaluating the results. In addition, the changes in the fundamental free vibration frequencies of the panels subjected to impact are examined to have an idea about the presence of the damage. The effect of curvature on the damage mechanisms of 3D printed honeycomb panels is studied by examining the contact force–deformation curves, energy profile diagrams, and SEM images. The experimental results indicate that the radius of curvature of the cellular panels highly affects the impact and free vibration behavior, and the change in the natural frequency due to the impact damage is more considerable for ABS than PLA.

Materialwissenschaft Und Werkstofftechnik, 2023

This study reports the results of a preliminary study of manufacturing aluminum–potassium feldspa... more This study reports the results of a preliminary study of manufacturing aluminum–potassium feldspar metal matrix composites including its castability and mechanical properties. The material was composed considering 0.25 %, 0.5 %, and 0.75 % additive ratios to examine the impact of the amount of potassium feldspar on the material and mechanical properties of the manufactured aluminum metal matrix composite material. Aluminum alloy (A356) was utilized as the matrix of the composition. The composite material was manufactured by the stir casting technique. The modulus of elasticity, yield strength, tensile strength, elongation, density, and quality index of the material parameters was taken into account to determine the materials′ practicality. The preliminary results indicated that potassium feldspar is a promising mineral to be utilized as an additive for aluminum metal matrix composites since it has a positive impact on mechanical properties. By optimizing the casting parameters, the positive aspects of the potassium feldspar may make the material more practical to be utilized in vast engineering applications.

SN Applied Sciences, 2021

This study presents the severity detection of pitting faults on worm gearbox through the assessme... more This study presents the severity detection of pitting faults on worm gearbox through the assessment of fault features extracted from the gearbox vibration data. Fault severity assessment on worm gearbox is conducted by the developed condition monitoring instrument with observing not only traditional but also multidisciplinary features. It is well known that the sliding motion between the worm gear and wheel gear causes difficulties about fault detection on worm gearboxes. Therefore, continuous monitoring and observation of different types of fault features are very important, especially for worm gearboxes. Therefore, in this study, time-domain statistics, the features of evaluated vibration analysis method and Poincaré plot are examined for fault severity detection on worm gearbox. The most reliable features for fault detection on worm gearbox are determined via the parallel coordinate plot. The abnormality detection during worm gearbox operation with the developed system is perform...

Applied Acoustics, Aug 1, 2022

Tekstil Ve Konfeksiyon, Dec 13, 2022

6th International Students Science Congress Proceedings Book

In this study, the Reynolds number effect on the aerodynamic coefficients is investigated using N... more In this study, the Reynolds number effect on the aerodynamic coefficients is investigated using NACA 4415 airfoil profile section. In the literature, there are quite a few experimental results for the low Reynolds numbers. The aim of the study is to fill this gap. For this purpose, three different Reynolds numbers which are 138e3, 154e3, and 170e3, are investigated during the experiments. The aspect ratio of the used airfoil is 4.76. The measurements of the aerodynamic forces are carried out using an open-jet type wind tunnel coupled with a three-component balance. Throughout the experiments, it is observed that the lift coefficients increase with the increasing Reynolds number.

Experimental Techniques, 2019

This paper focuses on extracting vibration region of gearboxes, monitoring parameters of the cond... more This paper focuses on extracting vibration region of gearboxes, monitoring parameters of the condition and detecting faults. When the gear contact surface tension exceeds the fatigue limit of the gear material because of excessive loading, inadequate lubrication, oil contamination and so on, tooth surface failures such as pitting, wear, tooth breakage, etc. occur. These types of defects in gear systems cause deterioration in the performance of gears, and thus significant operational problems may occur in the industry. In addition to existing studies related to fault detection, this study proposes extracting of vibration region to map the accelerations of the gearboxes. The proposed method consists of the following steps: the two-dimensional vibration region of the gearbox is created by using instantaneous accelerations taken from gearboxes in horizontal and vertical directions. Features of vibration region give valuable detail about the condition of gearboxes. Therefore, it is transformed into a binary image, and the features are extracted by using image processing algorithms. Finally, these features are used as inputs to the artificial neural network for classification of fault severity. To validate the proposed method, a two-stage helical gearbox and a worm gearbox are utilized as an experimental setup. As a result of the experiments carried out, it has been seen that the proposed method can accurately monitor the condition of the gearboxes and classify the severity of faults.

2012 11th International Conference on Machine Learning and Applications, 2012

ABSTRACT In this paper, we develop a web based interface which performs a wireless communication ... more ABSTRACT In this paper, we develop a web based interface which performs a wireless communication with ZigBee protocol for monitoring wind energy potential and also gathering custom reports for determination of the interested wind field. A custom printed circuit board layer is designed for interfacing with all the sensors that are in use. Web based interface is a product of responsive design for platform and device independency. This system enables scalable, accessible, reliable, low cost and low power consumption solution for renewable energy systems.

Tribology International, 2003

Dynamic loading of a rolling element bearing structure is modeled by a computer program developed... more Dynamic loading of a rolling element bearing structure is modeled by a computer program developed in Visual Basic programming language. The vibration response of the structure to the dynamic loading is obtained using a standard finite element package IDEAS. A force model is proposed to model the localized rolling element bearing defects. Time and frequency domain analyses are performed for diagnostics of rolling element bearing structures. Statistical properties of the vibration signals for healthy and defected structures are compared. The envelope (HFRT) method is employed in the frequency domain analysis. The effect of the rotational speed on the diagnostics of rolling element bearing defects is investigated. An optimum sensor location on the structure is sought. Effect of the structure geometry on the monitoring techniques is studied. An optimum monitoring method can be employed by analyzing the rolling element bearing structure following the procedure proposed in this study. The present commercial computer aided engineering packages can be used in special engineering applications such as condition monitoring of rolling element bearings.

Aviation, 2022

There are different types of airfoil used in many applications such as energy production, aerospa... more There are different types of airfoil used in many applications such as energy production, aerospace, mixing of fluid products. Design optimization studies are still being carried out on the airfoil type structures. The airfoil section is the most important factor affecting the quality and efficiency of the performed work. The aim of this study is the optimization of the airfoil shape to generate more lift than the original airfoil shape creates. For this purpose, Bézier curves are used to generate the airfoil polar points, XFOIL is used as a flow solver and MATLAB is used to create optimization codes using the genetic algorithm. The results show that the created optimal airfoil shape produces more lift than the original airfoil shape. In this study, design optimization studies are supported by flow analysis using ANSYS Fluent.

ABSTRACT: The aim of this study is to present the damped dynamic response of a symmetric laminate... more ABSTRACT: The aim of this study is to present the damped dynamic response of a symmetric laminated composite beam with different boundary conditions. A three-dimensional finite element model based on the classical laminated plate theory is used together with the Newmark integration method in order to obtain the dynamic response of the beam. A computer code written in MATLAB was developed in order to perform the dynamic analyses. The proportional damping which is referred to as Rayleigh damping is employed in the dynamic analyses. The impulse, step and moving load responses of the composite beam are presented for different damping ratios. The effect of the damping ratio on the dynamic magnification value, which is defined as the ratio between the dynamic and static displacements calculated for the mid point of the beam, is investigated. The normalized time values at which the maximum mid-point displacements occur are presented. The results reported in this article show that the large...

Disli kutularinin durum izlemesi, maliyet ve durus surelerinin azaltilmasi acisindan endustride o... more Disli kutularinin durum izlemesi, maliyet ve durus surelerinin azaltilmasi acisindan endustride onem verilen bir konudur. Bu calisma, bir helisel disli kutusunun durum izlemesi ve dis yuzeyinde olusturulmus oyukcuk hatalarinin disli kutusunun titresimine etkisinin tespiti uzerine odaklanmaktadir. Literaturde disli kutularinda ariza tespitiyle ilgili bulunan calismalara ek olarak, helisel disli kutusundan iki yonde ayni anda alinan anlik ivme degerleri kullanilarak disli kutusunun calisma anindaki titresim bolgesi cikartilir. Bu titresim bolgesi ikilik sistemde goruntu olarak kaydedilir ve goruntu isleme algoritmalari kullanilarak titresim bolgesinin alani hesaplanir. Titresim bolgesinin alani, disli kutusunun durumu hakkinda bilgi verir. Yapilan deneyler sonucunda, titresim bolgesi analizinin disli kutularinin durum izlemesi icin basarili bir yontem oldugu gorulmustur.

The monitoring of gearbox is a matter of concern to the industry in terms of cost and downtime re... more The monitoring of gearbox is a matter of concern to the industry in terms of cost and downtime reduction. This work focuses on the condition monitoring of a helical gearbox and the determination of the effect of pitting faults formed on tooth surface on vibration of helical gearbox. In addition to studies related to determination of faults in gearboxes in the literature, the vibration zone of the gearbox is extracted by using instantaneous acceleration values taken from the helical gearbox on the two directions. This vibration zone is recorded as an image in a binary system and the area of the vibration zone is calculated by using image processing algorithms. The area of the vibration zone gives information about the condition of the gearbox. As a result of the experiments carried out, it has been seen that the vibration zone analysis is a successful method for condition monitoring of a gearbox.

Journal of Vibration and Control, 2020

This study deals with the vibration reduction of a cantilever beam using air-jet thruster actuato... more This study deals with the vibration reduction of a cantilever beam using air-jet thruster actuators controlled by the particle swarm optimized quasi bang–bang controller. In this study, the finite ...

Diagnosis of worm gear faults using vibration analysis is difficult, for this reason; there have ... more Diagnosis of worm gear faults using vibration analysis is difficult, for this reason; there have been quite little publications, although worm gears are used significant machines in assorted industrial fields. Whenever a defect occurs in a worm system (e.g. pitting, abrasive wear), the performances of the gears deteriorate. Therefore, transmission of motion and power cannot be transferred as demanded. As a result, occurrence of fatal defects becomes inevitable. This paper focuses upon the early detection of localized pitting damages in a worm gearbox using artificial neural networks (ANN) and vibration analysis. Worm gear vibrations are acquired from an experimental rig utilizing a 1/15 worm gearbox. Statistical parameters of vibration signals in the frequency domains are used as an input to classifier ANN for multi-class recognition.