Helikopterlerde kullanılan küresel elastomerik yatakların mekanik tasarımı

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Thesis Type: Doctorate

Institution Of The Thesis: Kocaeli University, Fen Bilimleri Enstitüsü, Makina Mühendisliği Bölümü, Turkey

Approval Date: 2019

Thesis Language: Turkish

Student: MEHMET SAİD BAYRAKLILAR

Supervisor: Murat Makaraci

Open Archive Collection: AVESIS Open Access Collection

Abstract:

While there are many studies on planar elastomeric bearings in the international literature, there are few studies on spherical elastomeric bearings due to their multilayered and design difficulties. The elastomeric bearings are rigid against loads perpendicular to the sheets, while being flexible against loads parallel to the sheets. Thus, the spherical elastomeric bearings are rigid against the centrifugal force caused by the rotation of the helicopter propellers and provide flexibility against the flapping and rotational movement of the propeller. Stresses on elastomer material reduce bearing life; this means that the reduction of the maximum stress is very important for the elastomeric bearing life. In this study, mechanical behavior of spherical elastomeric bearing is modeled and simulated by nonlinear finite element code ABAQUS and stress distributions in elastomer layers are determined by using hyperelastic Mooney-Rivlin approach. The effect of spherical elastomeric bearing subjected to pressure loading and angular displacement loading, hole diameter, hole shape, elastomer layer thickness, number of layers and elastomer bearing profile on the maximum stress on the elastomer layers was investigated. The results showed that; the highest stress under pressure and angular displacement load occurs in the outermost final layers. It is possible to reduce the maximum stresses on all layers by changing the shape and thickness of the elastomer layers. The most significant reduction is made possible by the change in the hole diameter, thus extending the life of the elastomeric bearing, and hence reducing associated costs. This thesis also constitutes the first study on investigation and design of spherical elastomeric bearings in Turkey.