Finite element analysis and experimental study of dovetail attachments

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Havacılık ve Uzay Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2016

Öğrenci: AHMET ARDA AKAY

Danışman: ERCAN GÜRSES

Özet:

Dovetail-rim attachment is a critical component of an aeroengine compressor disc. Fretting fatigue is commonly seen in these attachments, which results to premature failures such as cracking or wear. Main cause of the fretting fatigue is high stress gradients occuring near the edges of contact. Since the problem involves contact, the effect of the certain contact parameters on the stress gradients is investigated. These contact stresses are non-singular and can converge to a value with successive mesh refinement. For this purpose, a submodelling procedure is introduced which can provide an accurate solution without the requirement of high computational resource. Submodelling is implemented on two different models and convergence of the peak stresses is observed within about five percent. Hence, three experimental studies are carried out on dovetail-rim attachments. For this purpose, an experimental setup is designed. Comparison of the finite element analysis and the experiment is performed. In the first two experiments, it is seen that the misalignment of the specimens causes asymmetric contact condition in the contact pairs between the disc and the blade parts of dovetail. Therefore, inconsistencies between finite element and experiment are observed. Certain changes are made in the experimental setup for the third experiment. Due to the alterations made, the third experiment gives results more consistent to the finite element. It is concluded that the measurements during the experiment are highly sensitive to the tolerances and imperfections in the experiment of the dovetail specimen.