Akademik Veri Yönetim Sistemi
Tezin Türü: Yüksek Lisans
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Havacılık ve Uzay Mühendisliği Bölümü, Türkiye
Tezin Onay Tarihi: 2018
Öğrenci: ZAFER ENGİN
Danışman: DEMİRKAN ÇÖKER
Özet:Multiaxial high cycle fatigue is an important failure mode for industrial applications as it is experienced by many engineering parts such as rotor blades and crankshafts. Determining the critical locations and especially the fatigue lives of such components have great importance. Therefore, a methodology is needed which would replace expensive and time-consuming test campaigns as it is not possible and feasible to simulate all the loading scenarios that component would experience during the service life. The purpose of this thesis is to evaluate the state-of-the-art multiaxial endurance criteria available in the literature, with respect to their capability of handling multiaxial load interactions, phase difference, mean stress, and calculation speed. The criteria transform the multiaxial stress state to a damage parameter which is compared with endurance limit to determine whether the structure endures the loading or not. In this thesis, criteria from the literature belonging to equivalent stress, invariant based and critical plane are considered. Extensive experimental data is obtained from literature to compare the estimations of the criteria and a MATLAB code is written for calculations. Life estimations are obtained for each experimental data and statistical analysis is performed for obtaining the general behavior of the criteria. Comparing each type of criteria we conclude that the equivalent stress methods give highly scattered estimations while invariant based methods yield vi more reliable results; however, best estimations are obtained by critical plane methods. For practical applications GAM (invariant based) or Papuga PCR (critical plane) may be implemented, former being fast and latter being more precise.