Sonlu Elemanlar Yöntemi ile Kompozit Konik Uçak Kanadının Serbest Titreşim Analizi

Öz

Mühendislik uygulamalarında kullanılan yapıların statik ve dinamik kuvvetlerin etkisi altındaki tepkileri, yapıların tasarım aşamasında önemlidir. Bir yapı için dinamik kuvvetlerin tepkisinin belirlenmesi, öncelikle yapının mod şekli ve titreşim frekansları olan serbest titreşim özelliklerinin değerlendirilmesiyle gerçekleştirilir. Bu makale, havacılık endüstrisinde kullanılan NACA4415 tasarımı ve farklı yaygın malzemelerden oluşan konik uçak kanat yapılarının modal analizlerini sunmaktadır. Ayrıca kıvrık kanatçık eklemlerinin (winglets) doğal frekanslar üzerindeki etkisi incelenmiştir. Ana kanat yapıları olan nervür (rib) ve kabuk (shell) yapıları CATIA kullanılarak oluşturulmuştur ve ANSYS Workbench'e aktarılmıştır. Analizler, uçak kanadının bir ucu (kök kiriş) serbestken diğer ucu (uç kirişi) sabitlenerek üç boyutlu bir konsol kiriş olarak düşünülerek yapılmıştır. Uçak kanat yapılarının ilk on doğal frekansları ve ilgili mod şekilleri elde edilmiştir. Sonuçlar; kanat uçlarına kıvrık kanatçık eklenmesinin doğal frekansları oldukça düşürdüğünü ve kabuk malzemesi olarak Karbon Epoksi EY kullanmanın, Kevlar Epoksi kullanımına göre daha yüksek doğal frekanslar oluşturduğunu göstermiştir.

Anahtar Kelimeler

• Serbest titreşim
• Doğal frekans
• Modal analiz
• Uçak kanadı
• Mod şekilleri

Free Vibration Analysis of Tapered Composite Aircraft Wing via the Finite Element Method

Öz

The responses of the structures used in engineering applications under the effects of static and dynamic forces are significant in the design phase. Determination of the response of dynamic forces for a structure is initially performed by the evaluation of free vibration characteristics that are mode shape of the structure and vibration frequencies. This paper presents modal analyses of tapered aircraft wing structures that consist of NACA4415 design and different common materials used in the aviation industry. Furthermore, the effect of winglets on natural frequencies is examined. The main wing structures as ribs and shells are drawn using CATIA and imported to ANSYS Workbench. Analyses have been carried out considering the aircraft wing as a three-dimensional cantilever beam by fixing one end (root chord) of the aircraft wing while the other end (tip chord) is free. The first ten modes of free vibration with their respective natural frequencies and mode shapes of the wing structures of the aircrafts are obtained. The results show that the winglets decrease the natural frequency noticeably and the shell material as Carbon Epoxy UD has been observed to have higher natural frequency compared with Kevlar Epoxy.

Anahtar Kelimeler

• Free vibration
• Natural frequency
• Modal analysis
• Aircraft wing
• Mode shapes

Kaynakça

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