PİSTONLU YARI-HERMETİK SOĞUTMA KOMPRESÖRÜ KRANK MİLİNİN SANKİ-STATİK YAKLAŞIMLA SONLU ELEMANLAR ANALİZİ

Year 2018, Volume: 23 Issue: 1, 97 - 110, 20.04.2018

Hüseyin Lekesiz

https://doi.org/10.17482/uumfd.301655

Cited By: 2

Abstract

Yarı-hermetik soğutma kompresörleri, arıza
durumunda kolay müdahale kolaylığı sağlarlar. Bu kompresörlerde kullanılan
krank milleri hem hafif hem de dayanıklı olmalıdır. Bu sebeple, doğru tasarım
ve doğru malzeme seçimi çok önemlidir. Bu kompresörler yüksek hızda
çalıştığından, zamana bağlı dinamik analiz kaçınılmaz olmaktadır. Ancak bu
yöntemle problem çözümü çok uzamaktadır ve yakınsama sağlamak zorlaşmaktadır.
Özellikle yataklardaki yağ basıncı değişimi vs gibi yapıdaki tüm dinamik
etkiler dikkate alındığında problem iyice karmaşıklaşmaktadır.  Probleme hızlı ancak statik yaklaşımdan daha
doğru bir çözüm elde etmek amacıyla bu çalışmada sanki-statik yaklaşım
kullanılmıştır. Kinematik ve kinetik analiz sonucu elde edilen kuvvetler yapıya
belli kabuller altında statik olarak uygulanmıştır. Ortaya çıkan maksimum
gerilme krank milinin yağlama plakasına bağlanan ucundaki fatura dibinde olup,
bu literatürdeki hasar örnekleriyle uyuşmaktadır. Analizler sonucunda atalet
etkisi %1.7 civarında olup, ele alınan krank mili için sanki-statik yaklaşımın oldukça
doğru bir yaklaşım olduğu gösterilmiştir.

Keywords

Yarı-hermetik, Kompresör, Krank Mili, Sonlu Elemanlar Yöntemi, Sanki-statik Yaklaşım, Atalet Kuvvetleri

Finite Element Analysis of Crankshaft of a Reciprocating Semi-Hermetic Compressor based on Quasi-Static Approach

Abstract

Semi-hermetic compressors brings the advantage
of easy repair in case of a breakdown. Crankshafts used in these compressors
are required to be light-weight and durable at the same time therefore, a
proper design along with a proper material selection becomes important. Due to
high speed of operation, a transient dynamic analysis may become necessary for
a proper evaluation of stresses and strains for the crankshaft. However,
dynamic analysis is computationally demanding especially when all dynamic
aspects are considered such as the influence of hydrodynamics of bearings etc.
Considering only static part of the loading may be oversimplified approach for
the problem. In this work, a quasi-static approach is used for the structural
analysis of crankshaft by performing kinematic and kinetic analysis to
determine forces with inertial effects included and then finite element
analysis to determine stresses and deflections. 
As expected, the maximum stress occurs in the radius of shaft connecting
to the bearing on oil spreader side. 
This is also verified in literature that fatigue cracks initiate at this
site of crankshaft.  The inertial effects
are investigated in detail and approximately around 1.7% of the loading is due
to inertial effect of piston and connecting rod. Therefore, it is anticipated
that quasi-static approach provides sufficiently accurate results. 

Keywords

Semi-hermetic, compressor, crankshaft, Finite Element Method, Quasi-Static Approach, Inertial Forces

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