Vibration fatigue analysis of structures installed on air platforms

Eldoğan, Yusuf
Although a component satisfies all operating static requirements, failures can still occur due to vibration induced fatigue. Vibration induced fatigue is a frequent phenomenon, in cases where the natural frequencies of the structures are excited by the loading. Hence, the methods which consider all dynamic characteristic of the structure should be used to obtain accurate fatigue life predictions. These methods in frequency domain are called vibration fatigue methods which give accurate, reliable and fast results. In this thesis, a numerical code is developed in order to predict fatigue life of structures and it is used for a bracket that is installed on an air platform. However, for verification of the numerical code, a cantilever beam is used as a case study at the beginning. First, finite element model of the cantilever beam is constructed and experimental analyses are performed to verify the finite element model. Then fatigue life is calculated using the numerical code and it is verified comparing the results obtained by both commercial software and performed fatigue tests. For predicting fatigue life of the bracket, flight test is performed in order to obtain acceleration loading. Finite element modeling of bracket and verification of it by experimental analyses are performed and finally, accelerated fatigue life of the bracket is obtained by the developed numerical code, commercial software and fatigue test. It is concluded that the results obtained from the fatigue analyses and fatigue test are considerably close enough to justify that the analysis is significantly accurate.


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...
Singularity robust inverse dynamics of planar 2-RPR parallel manipulators
Ider, SK (SAGE Publications, 2004-07-01)
In planar parallel robots, limitations occur in the functional workspace because of interference of the legs with each other and because of drive singularities where the actuators lose control of the moving platform and the actuator forces grow without bounds. A 2-RPR (revolute, prismatic, revolute joints) planar parallel manipulator with two legs that minimizes the interference of the mechanical components is considered. Avoidance of the drive singularities is in general not desirable since it reduces the ...
Optimum Profile Modifications for the Minimization of Dynamic Transmission Error
ÖZTÜRK, VEYSEL YALIN; Ciğeroğlu, Ender; Özgüven, Hasan Nevzat (2014-08-28)
An optimization study is performed target being the reduction of dynamic transmission error (DTE) for a selected operational range, where the operating torque and speed ranges are defined. For this purpose, two different models, i.e. a single degree of freedom (SDOF) lumped gear dynamics model and a multi-degree of freedom (MDOF) lumped model of a gear pair which is combined with shaft and bearing dynamics are employed. The differences between the optimization results obtained through loaded static transmis...
Mechanical fatique and life estimation analysis of printed circuit board components
Genç, Cem; Ünlüsoy, Yavuz Samim; Department of Mechanical Engineering (2006)
In this thesis, vibration induced fatigue life analysis of axial leaded Tantalum & Aluminum capacitors, PDIP and SM capacitors mounted on the printed circuit boards are performed. This approach requires the finite element model, material properties and dynamic characteristics of the PCB. The young modulus of the PCB material is obtained from 3 point bending tests, resonance frequencies are obtained from modal tests and transmissibility’s of the PCB are obtained from transmissibility tests which are used as ...
Performance evaluation of piezoelectric sensor/actuator on active vibration control of a smart beam
Şahin, Melin (SAGE Publications, 2011-01-01)
In this paper the performance of a piezoelectric sensor/actuator pair and self-sensing piezoelectric actuator on the investigation of vibration characteristics and active vibration control of a smart beam are presented. The performance of piezoelectric patches on actuation and sensing is evaluated by investigating the vibration characteristics of the smart beam via various excitation mechanisms and transduction systems. For active vibration suppression of the smart beam, robust controllers are designed and ...
Citation Formats
Y. Eldoğan, “Vibration fatigue analysis of structures installed on air platforms,” M.S. - Master of Science, Middle East Technical University, 2012.