Vibration fatigue analysis of equipments used in aerospace

Aykan, Murat
Metal Fatigue of dynamically loaded structures is a very common phenomenon in engineering practice. As the loading is dynamic one cannot neglect the dynamics of the structure. When the loading frequency has a wide bandwidth then there is high probability that the resonance frequencies of the structure will be excited. When this happens then one cannot assume that the structures response to the loading will remain linear in the frequency domain. Thus to overcome such situations frequency domain fatigue analysis methods exist which include the dynamics of the structure. In this thesis, a Helicopters Self-Defensive System̕s Chaff/Flare Dispenser Bracket is analyzed by Vibration Fatigue Method as a part of an ASELSAN project. To obtain the loading (boundary conditions), operational flight tests with accelerometers were performed. The obtained acceleration versus time signals are analyzed and converted to Power Spectral Densities (PSD), which are functions of frequency. In order to obtain the stresses for fatigue analysis, a finite element model of the bracket has been created. The dynamics of the finite element model was verified by performing experimental modal tests on a prototype. From the verified model, stress transfer functions have been obtained and combined with the loading PSD̕s to get the response stress PSD̕s. The fatigue analysis results are verified by accelerated life tests on the prototype. Also in this study, the effect of single axis shaker testing for fatigue on the specimen is obtained.


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Özsoy, Serhan; Kadıoğlu, Fevzi Suat; Department of Mechanical Engineering (2006)
Fatigue failure of metallic structures operating under dynamic loading is a common occurrence in engineering applications. It is difficult to estimate the response of complicated systems analytically, due to structure̕s dynamic characteristics and varying loadings. Therefore, experimental, numerical or a combination of both methods are used for fatigue evaluations. Fatigue failure can occur on systems and platforms as well as components to be mounted on the platform. In this thesis, a helicopter̕s Missile W...
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Multi-story reinforced concrete tunnel form buildings are one of the common structural types in regions prone to high seismic risk due to the buildings inherent earthquake resistance and ease of construction. Despite their good performance during earthquakes in 1999 in Turkey, and abundance of such structures scattered worldwide, current seismic codes and design provisions provide insufficient guidelines for their seismic design. As a compensatory measure, a series of modal and nonlinear static analyses are...
Citation Formats
M. Aykan, “Vibration fatigue analysis of equipments used in aerospace,” M.S. - Master of Science, Middle East Technical University, 2005.