Nihat YILDIRIM

University of Oxford, Mechanical Enginering, Faculty Member

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Ettore Pennestri'

"Tor Vergata" University of Rome

lotfi romdhane

American University of Sharjah

Minas Liarokapis

The University of Auckland

Isad Saric

University of Sarajevo

Daniel Condurache

Technical University of Iasi

Diyar Khalis Bilal

Salahaddin University-Erbil

Essam Esmail

University of Al-Qadisiyah

Ahmet Oven

Yildiz Technical University

Emmanouil Athanasopoulos

Aristotle University of Thessaloniki

Aris Zainul Muttaqin

Jember University, Indonesia

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Papers by Nihat YILDIRIM

Non Circular Gear Design Elliptical Gears as an Example

EJONS VI -INTERNATIONAL CONFERENCE ON MATHEMATICS -ENGINEERING -NATURAL & MEDICAL SCIENCES Adana/ TURKEY, 2019

Non-Circular gears (NCG) are special gears, designed with special characteristics and purposes. W... more Non-Circular gears (NCG) are special gears, designed with special characteristics and purposes. While a regular circular gear is optimized to transmit torque and speed to another engaged member with fixed transmission ratio and with minimum noise, wear and with maximum efficiency, a non-circular gear&#39;s main objective might be transmission ratio variations, axle displacement oscillations and more. Non-circular gears are widely used in various industrial fields because they can meet special variable transmission requirements. Center-distance of non-circular gears is usually fixed as circular gears, but the main difference is that the radius of each gear is a function of the rotating angle in case of non-circular gears. What makes the non-circular gears unique is the fact that although cams or linkages can provide these special types of motion requirements, non-circular gears can provide simpler, more compact and more accurate solutions. This paper is about applying the design method to elliptical gears as an example, including generation of the mating pitch curves and teeth profiles for each gear of the set, by utilizing the MATLAB software. The method of designing non-circular gears is relatively simple enough, but the irregular shapes of the pitch curves come with difficulties of finding the proper equations and dealing with them. The design method can be explained briefly as finding the pitch curves of gears and generating the teeth profiles on each gear to satisfy the meshing and rolling of the gearset. In other words, this method depends on obtaining the gear tooth surfaces as the envelope to the family of tool surfaces, which can be achieved by using the same tools (rack cutters, hobs, and shapers) that are conventionally used for the manufacture of circular gears. The process of imaginary rolling of the tool on the noncircular pitch curve can be accomplished by proper relations between the motions of the tool and the non-circular gear&#39;s work piece in the process of cutting. Based on the general method stated, it will be possible to apply the same method for special cases of non-circular gears such as elliptical gears, triangular gears, logarithmic gears, …etc and the work here focuses on the design and construction of elliptical gears.

Ağır Yük Düz ve Helis Dişlilerin Performans Analizi ve Profil Optimizasyonu

Makina Tasarım ve İmalat Dergisi, Nov 2, 2003

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Alumi̇nyum Alaşimlarinin Mekani̇k Özelli̇kleri̇

The use of fusion welding process for 2024-T3 and 6061-T6 alloys is not preferred because of the ... more The use of fusion welding process for 2024-T3 and 6061-T6 alloys is not preferred because of the heat generated from the thermal cycle of the welding which can affect the heat treatments of base metals. Therefore, solid state nature of friction stir welding (FSW) process is generally used in order to join these dissimilar alloys. This experimental study presents the effect of variable rotational and traverse speeds on hardness, bending, and tensile properties of 2024-T3 and 6061-T6 alloys joints produced by FSW. Experimental results have shown that defect free friction stir welded joints of good quality successfully produced from 3 mm thick sections of these alloys.

Some Guidelines on the Use of Profile Reliefs of High Contact Ratio Spur Gears

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2005

With reference to the previous articles of the author(s) based on the systematic approach to the ... more With reference to the previous articles of the author(s) based on the systematic approach to the profile relief design of both low contact ratio and high contact ratio spur gears, some guidelines are drawn for the use of short and double reliefs of the HCRG profile design under the effect of realistic parameters like variable tooth stiffness and manufacturing errors regarding the profile relief values. Root stress of the double relief can be minimized by optimizing the maximum tooth load value, hence the tooth load diagram with constant and variable tooth stiffness. Interaction of the manufacturing errors with the relief parameters is put into a form of analytical relation between manufacturing grades, hence the manufacturing tolerance and some gear parameters such as contact ratio, base pitch, and the load at which the smooth transmission error curve is required. In case of double relief, design load plays a major role in its selection. A relation and also a tabular form of guideli...

CFD Simulation of Turbulent Flow Around a Shrouded Spur Gear for Predicting Load-Independent Windage Power Losses

Load-independent power losses, namely windage power losses, are of big concern when the gearbox i... more Load-independent power losses, namely windage power losses, are of big concern when the gearbox is loaded without oil lubrication. Air and/or oil mist are the fluid medium and should be studied before the addition of oil churning and squeezing losses. In this study, firstly, two dimensional computational fluid dynamics (CFD) approaches are followed to understand the behavior of the medium around the shrouded, rotating spur gear for the 40 teeth geometry of Seetharaman and Kahraman. For the sake of simplicity and fast convergence, periodic boundary conditions are employed with addition of carefully selected turbulence models in ANSYS Fluent 18.2. In the second part, same boundary conditions are applied to three dimensional study for the 23 teeth geometry of Seetharaman and Kahraman. Secondary flows and pressure contours are captured well. Windage power loss calculations are compared with the numerical study of Chaari et al. for different angular velocities for two-dimensions. As the ...

Recent Developments in Aerospace Gears and Gearbox Designs

Aerospace power transmission elements and units like gears and gearboxes are critical componentsw... more Aerospace power transmission elements and units like gears and gearboxes are critical componentswhich need to be designed, manufactured and installed for a well performing fail-safe operation. Recent development of such components has seen rather satisfying improvements regarding different subjects like materials, design, manufacturing processes, surface treatment, etc. While cleanliness of material and special alloys help increase the strength of gear material, different design methods help reduce stresses under service loads. Similarly, different manufacturing methods help reduce surface burn like defects while material surface coatings help increase the resistance to wear and pitting like failures of both gears and bearings. Different examples of recent developments in aerospace gears and gearbox designs are provided in this paper to keep readers up to date with the aerospace power transmission technology. Keywords : aerospace, development, design, gear, gearbox, performance

Effect of Welding Parameters on the Mechanical Properties of Dissimilar Aluminum Alloys 2024-T 3 to 6061-T 6 Joints Produced by Friction Stir Welding

A study on prediction validation of meshing gear pair backlash under various manufacturing and assembly errors

MATEC Web of Conferences

Backlash is a need for proper gear mesh but also a defect if not controlled closely. Few studies ... more Backlash is a need for proper gear mesh but also a defect if not controlled closely. Few studies have focused on controlling backlash with some mechanical solutions that can be applied. Few other studies have shown interest in estimation of minimum / maximum variable backlash. The operating backlash of meshing gears is affected by many factors among which runouts, pitch errors and tooth thicknesses are the three most pronounced manufacturing errors. All these three parameters are the measurable ones once the gears are manufactured. Center distance and phasing of meshing gears are the examples of assembly errors which may affect the operating backlash. A software has been developed to predict likely maximum and minimum backlash of a gear pair selected arbitrarily and assembled together. For the validation of software predictions an experimental setup is needed for backlash measurements. Thus, a special test rig is designed and constructed for experimental measurements of the operatin...

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Kaynak Parametreleri̇ni̇n Sürtünme Kariştirma Kaynaği İle Bi̇rbi̇ri̇ne Kaynaklanmiş 2024-T3 6061-T6 Alumi̇nyum Alaşimlarinin Mekani̇k Özelli̇kleri̇ Üzeri̇ndeki̇ Etki̇leri̇ni̇n İncelenmesi̇

Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi

An improvement on helicopter transmission performance through use of high contact ratio spur gears with suitable profile modification design

Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering

This is a design/development study on helicopter transmission that had improved performance in te... more This is a design/development study on helicopter transmission that had improved performance in terms of vibration and noise behaviour, in compliance with surface durability requirement, compared with what was achievable with previous designs. Different spur gears of both low and high contact ratios (HCRs) have previously been designed and tested in helicopter transmissions with different profile modifications but with limited performance improvement. The desired performance, however, was achieved through the use of a suitable profile modification for the HCR spur gears in mesh. Profile modification type of ‘double relief’ was applied for the first time to two sets of helicopter transmission spur gears, both with HCRs. Possibility of corner contact was avoided while achieving a relatively low value of peak-to-peak transmission error in ‘full load range of gears operating conditions’, which was not usually satisfied by conventional profile designs. With the new profile modification de...

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Unité de percolation permettant d’extraire une huile de qualité élevée à partir d’olives et de fruits oléagineux de type olive

Aircraft with a Modified Gear, and Method of Producing the Gear

Asme DETC47404 2011

Aerospace applications require special procedures for component design and manufacturing. Spur ge... more Aerospace applications require special procedures for component design and manufacturing. Spur gears of different designs, because of their simpler geometries, are used in vital units-transmissions of helicopters and alike aerospace vehicles. In this study, performances of various profile designs of previously researched low and high contact ratio spur gears with some realistic design parameters are studied. Effects of the realistic parameters of variable tooth pair stiffness, relief shape, and adjacent pitch error on Transmission Error (TE), tooth loads and root stresses are presented; composition of these parameters determines the efficiency of the gearbox assembly. Detail of minimization of tooth root stress through optimized/proper design of relief is described. More comprehensive comparison of the gear tooth profile design cases is done to be able to guide aerospace transmission designers for practical applications with realistic parameters for each of the design cases. A preference order is done among the design cases, depending on effect of some design parameters on the results such as tooth loads, tooth root stresses, TE curves and peak-to-peak TE values. NOMENCLATURE F transmitted load per unit facewidth, N/mm F d design load per unit facewidth, N/mm f normalized transmitted load f d normalized design load fopt normalized load at which smooth TE curve is obtained f t,max normalized maximum tooth load PE adjacent pitch error PL pivotal point of the double relief (see figure 1) TEpp peak-to-peak transmission error value ε α transverse contact ratio

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A TRIZ Approach to Present and Future Development of the Oliveoil Processing Technology

Based on background knowledge and well proven methods of the TRIZ - Theory of Inventive Problem S... more Based on background knowledge and well proven methods of the TRIZ - Theory of Inventive Problem Solving- an approach is introduced to analyze the present developments of the olive-oil processing technologies. Some of the processing stages like preperation of the olive paste and extraction of the liquid phase from the paste are analyzed and discussed in the lights of the

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Further Evaluation of Spur Gear Tooth Profile Designs Used in Heavily Loaded Transmissions

Volume 8: 11th International Power Transmission and Gearing Conference; 13th International Conference on Advanced Vehicle and Tire Technologies, 2011

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A study on prediction & validation of meshing gear pair backlash under various manufacturing and assembly errors

6th International BAPT Conference “Power Transmissions 2019” MATEC Web Conf. Volume 287, 2019, 2019

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Non Circular Gear Design Elliptical Gears as an Example

EJONS VI -INTERNATIONAL CONFERENCE ON MATHEMATICS -ENGINEERING -NATURAL & MEDICAL SCIENCES Adana/ TURKEY, 2019

Ağır Yük Düz ve Helis Dişlilerin Performans Analizi ve Profil Optimizasyonu

Makina Tasarım ve İmalat Dergisi, Nov 2, 2003

Download

Alumi̇nyum Alaşimlarinin Mekani̇k Özelli̇kleri̇

Some Guidelines on the Use of Profile Reliefs of High Contact Ratio Spur Gears

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2005

CFD Simulation of Turbulent Flow Around a Shrouded Spur Gear for Predicting Load-Independent Windage Power Losses

Recent Developments in Aerospace Gears and Gearbox Designs

Effect of Welding Parameters on the Mechanical Properties of Dissimilar Aluminum Alloys 2024-T 3 to 6061-T 6 Joints Produced by Friction Stir Welding

A study on prediction validation of meshing gear pair backlash under various manufacturing and assembly errors

MATEC Web of Conferences

Download

Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi

An improvement on helicopter transmission performance through use of high contact ratio spur gears with suitable profile modification design

Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering

Download

Unité de percolation permettant d’extraire une huile de qualité élevée à partir d’olives et de fruits oléagineux de type olive

Aircraft with a Modified Gear, and Method of Producing the Gear

Asme DETC47404 2011

Download

A TRIZ Approach to Present and Future Development of the Oliveoil Processing Technology

Download

Further Evaluation of Spur Gear Tooth Profile Designs Used in Heavily Loaded Transmissions

Volume 8: 11th International Power Transmission and Gearing Conference; 13th International Conference on Advanced Vehicle and Tire Technologies, 2011

Download

A study on prediction & validation of meshing gear pair backlash under various manufacturing and assembly errors

6th International BAPT Conference “Power Transmissions 2019” MATEC Web Conf. Volume 287, 2019, 2019

Download

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