Biyel Optimizasyonu

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Tarih
2013-01-06
Yazarlar
Kaya, Tolga
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Özet
Biyel, doğrusal hareketin dönme hareketine ya da tam tersine çevrilmesinde ve günümüzde içten yanmalı motorlarda kullanılan en önemli parçalarıdan biridir. Günümüzde hızla gelişen teknoloji ile birlikte düşük hacim ve yüksek güç değerlerinde çalışan motorların geliştirilmesiyle daha hassas, daha hafif, daha dayanıklı ve daha ekonomik motor parçalarına ihtiyaç duyulmuştur. Motora ait tüm parçalar içerisinde ani değişen yüklere maruz kalan en belirgin parça biyeldir. Yüksek hızlarda ve güçlerde çalışan biyellerde oluşan temel gerilmeler, öncelikli olarak biyel koludan başlara geçiş bölgesinde olmak üzere, ciddi deformasyon ve yorulma eğilimine sebep olmaktadır. Bu çalışma, genel olarak biyelin özellikleri, yapısal açıdan içinde bulunduğu çalışma şartlarına dayanarak krank açısına bağlı maruz kaldığı kuvvetlerin incelenmesi, bu kuvvetlere bağlı olarak stres analizlerinin gerçekleştirilmesi ve elde edilen sonuçlar ışığında biyel optimizasyonunun yapılması olarak dört ana kısımdan oluşmaktadır. Mathcad ve MS Excel programları kullanılarak biyele ait parametreler ile biyele ait yer değiştirme denklemleri, biyele bağlı hız ve ivmenin tespiti yapılmıştır. Tespiti yapılan değerlere dayanarak maksimum F kuvvetinin hangi krank açısında oluştuğu tespit edilmiştir. Krank-biyel mekanizması matematiksel olarak modellenmiştir. Daha sonra üç adet biyel modeli Solidworks progamı ile genel biyel tasarımı esaslarına göre günümüzdeki biyel tasarımlarından esinlenilerek üç boyutlu olarak tasarlanmıştır. Tasarımı yapılan üç biyel geometrisi için elde edilen kuvvetler kullanılarak FEM (sonlu elemanlar yöntemi) ile stres analizleri gerçekleştirilmiştir. Bu analizler için krank-biyel mekanizmasının analiz modeli oluşturulmuştur. Mekanizmaya ait pin, yatak ve krank muylusu modellenmiştir. Tespit edilen krank açısına bağlı maksimum F kuvveti ile stres analizleri yapılmıştır. Bu tez çalışmasında sıcaklık ve hava şartları dikkate alınmamış, yük dağılımının homojen olduğu kabul edilmiştir. Son olarak analizlerden çıkan sonuçlara göre en uygun biyel tercih edilip yük azaltma çalışmaları ile biyel optimizasyonu yapılmıştır. Böylece bir biyelin sıfırdan tasarımı gerçekleştirilip elde edilen matematiksel bilgilerin ışığında analizleri tecrübe edilip tasarımda gerekli düzeltmeler yapılarak eldeki verilere göre bir biyel elde edilmiştir.
In order to understand the true impact the automobile has had on our society, we would have to go back in time over one hundred years. A time without the simplicity of hopping into a vehicle to take us anywhere we want to go is almost unfathomable to many Americans. But for the early automotive engineers, the tremendous advancements in automotive technology would be even more surprising. In the last 50 years, cars have learned to think, adjust, and even protect. But this is just the tip of the iceberg. High performance is now the catch phrase. The vast majority of people want a vehicle that will get them from point A to point B as easily as possible, but also put a little smile on their faces. Often times, the smile is created by a quick punch of the accelerator and accompanied by a feeling of immense power and control. The auto manufacturers are well aware of this, and to achieve it, they design faster, lighter, and more efficient engines to do the job. But exactly it is known, what happens inside an engine, and what are the risks involved in designing the strongest engine on the block. Nowadays the main problems in the field of development and improvement of motor-vehicle and tractor engines are concerned with wider use of diesel engines, reducing fuel consumption and weight per horsepower of the engines and cutting down the costs of their production and service. The engine-pollution control, as well as the engine-noise control in service have been raised to a new level. Far more emphasis is given to the use of computers in designing and testing engines. Ways have been outlined to utilize computers directly in the construction of engines primarily in the construction of diesel engines. The challenge of these problems requires deep knowledge of the theory, construction and design of internal combustion engines on the part of specialists concerned with the production and service of the motor vehicle and tractor engines. In this project, one component of an engine in particular, the connecting rod, will be analyzed. Being one of the most integral parts in an engine’s design, the connecting rod must be able to withstand tremendous loads and transmit a great deal of power. It is no surprise that a failure in a connecting rod can be one of the most costly and damaging failures in an engine. But simply saying that isn’t enough to fully understand the dynamics of the situation. This work presents a three-dimensional finite element analysis, which describes the behaviour of a connecting rod under gas pressure. The connecting rod is moving in a complex environment during engin operation. The pushing force takes into account the most important load. Also there is pulling force that effects the connecting rod because of the interia loads of piston and piston elemens (pin, ring etc.). Pushing force reaches it’s maximum limits by gas pressure, pulling force reaches it’ s maximum limits at maximum speed. The response of the simulated model by critical loads makes it possible to know and to analyse the operating forces, the corresponding maximum gaz pressure and the interia load. A connecting rod is the most common part in converting linear motion to rotating motion and combustion engines in daily life. Today, the automotive industry needed less toleranced, less mass and more stable, more economic motor parts because of the less space and high torque ratings with the speedly growing technology. The most known part in a combustion engine which comes face to face with quickly changing forces is a connecting rod. Tensions and compressions couses seriously deformations and fatigue on connecting rods that works in high velocity and torque. This article includes general properties about the connecting rod, research about forces upon crank angle with corresponding to its working dependencies in a structural mentality, study on the stress analysis upon to this forces gained from calculatinos and optimization with the data that gained from the analysis. Displacement, velocity and acceleration of the system is calculated corresponding with connecting rod’s known parameters with using Mathcad and MS Excel programs. The crank angle found which crank-slider mechanism has maximum F force with calculated data. Firstly, crank-slider mechanism is designed in numerical model. After that, three of connecting rod designed as a three-dimensional model in Solidworks program corresponding with desing fundamentals of a connecting rod and affect of made designs. Stress analysis applied on this three connecting rods with using calculated forces in FEM (finite element method). A model designed as a crank-slider mechanism for this analysis. Pin of piston, housing and crank pin is created for this crank-slider mechanism. Stress analysis applied with calculated F force correponding the crank angle. In this study, temperature and operating conditions are not cared, additionally it is accepted that a homogen force is applied on the system. The connecting rod must be of a certain weight because it has an effect on the engine. It if the rod is light, then the engine will be able to move faster and accelerate more quickly. But weight is not the only important thing; the connection rod must be light and strong at the same time. It should be strong enough to resist all forces produced by the engine, as well as the powerful force that the piston creates when it is moving to the dead center. If the connection rod is weak, that force made by the piston can break it in half or pull it out from its place. After all, the most sucessfull connecting rod design selected and made optimization with weight decreasing and supporting of weak points on it. By the way, an optimized connecting rod created with design from the beginning, develop of numerical equations corresponding with calculating it’s working loads. Due to its large volume production, it is only logical that optimization of the connecting rod for its weight or volume will result in large-scale savings. It can also achieve the objective of reducing the weight of the engine component, thus reducing inertia loads, reducing engine weight and improving engine performance and fuel economy. For conclusion, the connecting rod can be designed and optimized under a load range comprising tensile load corresponding to 360o crank angle at the maximum engine speed as one extreme load, and compressive load corresponding to the peak gas pressure as the other extreme load.
Açıklama
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2012
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2012
Anahtar kelimeler
biyel, optimizasyon, analiz, connecting rod, optimization, analysis
Alıntı