Vibration fatigue analysis of equipments used in aerospace

Download
2005
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.

Suggestions

A detailed analysis for evaluation of the degradation characteristics of simple structural systems
Kurtman, Burak; Erberik, Murat Altuğ; Department of Civil Engineering (2007)
Deterioration in the mechanical properties of concrete, masonry and steel structures are usually observed under repeated cyclic loading in the inelastic response range. Therefore such a behavior becomes critical when these types of structures are subjected to ground motions with specific characteristics. The objective of this study is to address the influence of degrading behavior on simple systems. The Structural Performance Database on the PEER web site, which contains the results of cyclic, lateral-load ...
Inelastic seismic response analysis and design of torsionally coupled systems
Kaatsız, Kaan; Sucuoğlu, Haluk; Department of Civil Engineering (2019)
Torsional coupling due to irregular placement of load resisting members and/or uneven mass distribution along a story plan is a very common phenomenon in structural systems. Unsymmetrical-plan buildings with stiffness and/or mass asymmetry behave considerably different compared to regular buildings when they are subjected to earthquake-induced forces. Modern earthquake resistant design related code provisions that employ capacity design principles aim to achieve a certain amount of ductility in the structur...
Seismic retrofitting of highway bridges in Illinois using friction pendulum seismic isolation bearings and modeling procedures
Dicleli, Murat (Elsevier BV, 2003-07-01)
In this paper, the economical and structural efficiency of friction pendulum bearings (FPB) for retrofitting typical seismically vulnerable bridges in the State of Illinois is studied. For this purpose, a bridge was carefully selected by the Illinois Department of Transportation (IDOT) to represent typical seismically vulnerable bridges commonly used in the State of Illinois. A comprehensive structural model of the bridge was first constructed for seismic analysis. An iterative multi-mode response spectrum ...
Vibration induced stress and accelerated life analyses of an aerospace structure
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...
Seismic vulnerability, behavior and design of tunnel form building structures
Balkaya, C; Kalkan, E (Elsevier BV, 2004-12-01)
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.