Dörtçubuk mekanizmasının tam dengelenmesi
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Dosyalar
Tarih
2023
Kurum Yazarları
Ali, Mohamed Awaleh
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Bursa Uludağ Üniversitesi
Özet
Bu çalışmada bir dört çubuk mekanizmasında atalet kuvvetleri ve atalet momentlerinin tam dengelenmesi incelenmektedir. Tam dengeleme mekanizmalarda ciddi bir sorundur ve çoğu hallerde atalet kuvvetleri dengelemesiyle yetinilir veya hem atalet kuvvetleri hem de atalet momentlerinin kısmi dengelenmesi tercih edilir. Bu alanda pek çok yayın vardır; ancak daha ziyade metot önerilmektedir. Bunun dışında optimizasyon yöntemleriyle mekanizmanın tüm fiziki parametrelerini değiştirerek dengeleme problemini çözmeye yönelik çalışmalar da mevcuttur. Ancak bu durumda mekanizma uzuvlarının geometrisinde ciddi değişimler olmaktadır. Ayrıca uzuvların kütleleriyle kütle atalet momentleri arasındaki ilişkiden ötürü bunların bağımsız olarak dengeleme amaçlı optimizasyon prosesine sokulması elde edilen yeni değerlerin tasarım aşamasında kolayca sağlanamamasına yol açabilmektedir. Bu nedenle çalışmamızda klasik yaklaşımla mekanizma uzuvlarına karşı ağırlıklar ve dönen elemanlar ilave ederek mekanizmada tam dengelemenin nasıl yapılabileceği sayısal örnek yardımıyla gösterilmektedir. Bununla birlikte mekanizmada dönen ve ötelenen kütleler arttığı için ihtiyaç duyulan motor torkunda artış gözlenmektedir. Sonuç itibariyle tam dengelemeyle yüksek torklar ve dolayısıyla daha büyük motor gücü arasında bir tercih yapılması veya makul bir ara çözümde buluşulması gerekmektedir. Çalışmada önce dengelenmemiş mekanizma incelenmektedir. Mekanizma tek serbestlik dereceli olduğundan Lagrange yöntemiyle hareket denklemi elde edilmiş ve kinematik taleplerin tamamen sağlandığı kabulü altında mekanizmanın bir periyodunda ihtiyaç duyulan motor torku değişimi bulunmuştur. Bilahare Euler-Newton metoduyla hareket denklemleri çıkarılıp çözülerek mafsal reaksiyon kuvvetleri ve bu suretle mekanizmadan şasiye intikal eden kuvvetler hesaplanmıştır. Dengeleme yapıldıktan sonra sistemin yine iki farklı yöntemle hareket denklemleri çıkarılarak motor torku değişimi ve şasiye yani gövdeye aktarılan kuvvet ve moment bulunarak dengelenmemiş haldeki değerlerle mukayese edilmiştir. Sonuçlar zemine intikal eden sarsma kuvvetleri ve sarsma momentlerinin giderildiğini, buna karşılık beklendiği gibi motor torku değerlerinde ciddi artış olduğunu göstermektedir.
In this study, the exact balancing of the inertia forces and inertia moments in a four-bar mechanism are investigated. Full balancing is a significant problem in mechanisms and in most cases balancing of inertia forces is sufficient or partial balancing is preferred for both inertia forces and moments of inertia. There are many publications in this field; however, only methods are proposed in most cases. Apart from this, there are studies to solve the balancing problem by changing all the physical parameters of the mechanism with optimization methods. However, in this case, there are serious changes in the geometry of the mechanism links. In addition, due to the relationship between the masses of the links and their mass moments of inertia, putting them into the optimization process for balancing purposes independently may lead to the fact that the new values obtained cannot be easily realized at the design stage. For this reason, in our study, it is shown with the help of numerical examples how full balancing can be made in the mechanism by adding counterweights and rotating elements to the mechanism links within the classical balancing theory. However, as the rotating and translating masses in the mechanism increase, the required engine torque increases. As a result, a choice has to be made between full balancing and higher torques and therefore greater engine power, or a reasonable intermediate solution has to be found. In this study, the unbalanced mechanism is examined first. Since the mechanism has only one degree of freedom, the equation of motion is obtained with the Lagrangian method and the required motor torque change in one period of the mechanism is found under the assumption that the kinematic demands are fully satisfied. Afterwards, the equations of motion were derived with the Euler-Newton method, and solved. Later, the joint reaction forces and thus the forces transmitted from the mechanism to the chassis were calculated. After balancing, the motion equations of the system were again derived with two different methods, and the engine torque change and the force and moment transferred to the chassis, that is, to the ground, were found and compared with the values in the unbalanced state. The results show that the shaking forces and shaking moments transmitted to the body are eliminated, but there is a significant increase in the motor torque values as expected.
In this study, the exact balancing of the inertia forces and inertia moments in a four-bar mechanism are investigated. Full balancing is a significant problem in mechanisms and in most cases balancing of inertia forces is sufficient or partial balancing is preferred for both inertia forces and moments of inertia. There are many publications in this field; however, only methods are proposed in most cases. Apart from this, there are studies to solve the balancing problem by changing all the physical parameters of the mechanism with optimization methods. However, in this case, there are serious changes in the geometry of the mechanism links. In addition, due to the relationship between the masses of the links and their mass moments of inertia, putting them into the optimization process for balancing purposes independently may lead to the fact that the new values obtained cannot be easily realized at the design stage. For this reason, in our study, it is shown with the help of numerical examples how full balancing can be made in the mechanism by adding counterweights and rotating elements to the mechanism links within the classical balancing theory. However, as the rotating and translating masses in the mechanism increase, the required engine torque increases. As a result, a choice has to be made between full balancing and higher torques and therefore greater engine power, or a reasonable intermediate solution has to be found. In this study, the unbalanced mechanism is examined first. Since the mechanism has only one degree of freedom, the equation of motion is obtained with the Lagrangian method and the required motor torque change in one period of the mechanism is found under the assumption that the kinematic demands are fully satisfied. Afterwards, the equations of motion were derived with the Euler-Newton method, and solved. Later, the joint reaction forces and thus the forces transmitted from the mechanism to the chassis were calculated. After balancing, the motion equations of the system were again derived with two different methods, and the engine torque change and the force and moment transferred to the chassis, that is, to the ground, were found and compared with the values in the unbalanced state. The results show that the shaking forces and shaking moments transmitted to the body are eliminated, but there is a significant increase in the motor torque values as expected.
Açıklama
Anahtar kelimeler
Dörtçubuk mekanizması, Kütle dengelemesi, Tam dengeleme, Sarsma kuvvetleri ve momentleri, Fourbar linkage, Mass balancing, Complete balancing, Shaking forces, Shaking moments
Alıntı
Ali, M. A. (2023). Dörtçubuk mekanizmasının tam dengelenmesi. Yayınlanmamış yüksek lisans tezi. Bursa Uludağ Üniversitesi Fen Bilimleri Enstitüsü.