Acoustic fatigue procedure validation and application on cavity wall

Küden, Zeynep
Acoustic loading formed due to boundary layer fluctuation, engine efflux and separated aerodynamic flow cause vibration that may result in fatigue failure of the structure. The subject of this thesis deals with the analytical acoustic fatigue procedure composition and validation in addition to critical wall stress analysis of representative weapon bay. It is aimed to feed the design process of the projects during its preliminary stages from structural point of view. The thesis can be discussed into two section. Firstly, analytical procedure on acoustic fatigue is composed by Engineering Science Data Unit documents. Verification is achieved via Finite Element Method by assuming single degree of freedom theory; since, fatigue damage is usually dominated by one mode, although acoustically induced vibration usually consists of several response modes. Analytical method covers the extraction of dynamic characteristics, response under unit loading, acoustic loading generation and dynamic stress response of the simple-geometry structures. Obtained stress levels are used to predict endurance life of the structure with simplified equations. Secondly, critical wall stress response analysis of cavity shape structure, represents weapon bay of an aircraft, with different boundary conditions is carried out. These boundary conditions arise from different housing cases of the internal members of the aircraft. Effects of changes in the internal rib structures’ location on the structural response is investigated for different Mach numbers and controlling methods, spoiler and swept rear wall alike, applied to reduce the pressure fluctuation generated due to the flow over cavity.


Vibration reduction by using two tuned mass dampers with dry friction damping
Doğan, Muhammed Emin; Ciğeroğlu, Ender (null; 2019-02-20)
Vibration reduction of a single-degree-of-freedom system connected to two tuned mass dampers (TMDs) equipped with dry friction dampers is considered in this work. The system is subjected to sinusoidal base excitation. Parameters of TMDs are optimized to minimize the peak values of the response of the primary system. Harmonic balance method (HBM) is used to obtain the steady state solution of the three-degrees-of-freedom nonlinear system in frequency domain. Newton’s method with arc length continuation is ut...
Acoustic Fatigue and Dynamic Behavior of Composite Panels Under Acoustic Excitation
Uz, Canan; Ata, Tamer T. (2016-01-28)
Composite panels in aircraft structures are exposed to fluctuating sound pressure originating mostly from engine noise and air flow. In this paper, acoustic fatigue and dynamic response of composite panels under acoustic excitation are investigated numerically. Composite panel is simulated with finite element analysis. The panel is considered clamped at one edge, whereas the opposite edge is assumed to be free. The panel is subjected to random repeated loading generated by sound waves. The analysis estimate...
Vibration reduction of a structure by using nonlinear tuned vibration absorbers
Dogan, Muhammed Emin; Ciğeroğlu, Ender (2021-01-01)
Tuned Vibration Absorbers (TVA) are commonly used in reducing undesirable vibrations of mechanical structures. However, TVAs work in a very limited frequency range and if the excitation frequency is outside of this range, they become ineffective. In order to solve this problem, researchers started to consider nonlinear TVAs for vibration attenuation. In this study, dynamic behavior of a linear Euler-Bernoulli beam coupled with a nonlinear TVA is investigated. The system is subjected to sinusoidal base excit...
Seismic performance of chevron braced steel frames with and without viscous fluid dampers as a function of ground motion and damper characteristics
Dicleli, Murat (Elsevier BV, 2007-08-01)
This study is aimed at comparing the seismic performance of steel chevron braced frames (CBFs) with and without viscous fluid dampers (VFDs) as a function of the intensity and frequency characteristics of the ground motion and VFD parameters. For this purpose, comparative nonlinear time history (NLTH) analyses of single and multiple story CBFs with and without VFDs are conducted using ground motions with various frequency characteristics scaled to represent small, moderate and large intensity earthquakes. A...
Acoustic radiation from a fluid-filled, subsurface vascular tube with internal turbulent flow due to a constriction
Yazıcıoğlu, Yiğit; Spohnholtz, Todd; Martin, Bryn; Loth, Francis; Bassiouny, Hisham S. (Acoustical Society of America (ASA), 2005-08-01)
The vibration of a thin-walled cylindrical, compliant viscoelastic tube with internal turbulent flow due to an axisymmetric constriction is studied theoretically and experimentally. Vibration of the tube is considered with internal fluid coupling only, and with coupling to internal-flowing fluid and external stagnant fluid or external tissue-like viscoelastic material. The theoretical analysis includes the adaptation of a model for turbulence in the internal fluid and its vibratory excitation of and interac...
Citation Formats
Z. Küden, “Acoustic fatigue procedure validation and application on cavity wall,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Mechanical Engineering., Middle East Technical University, 2019.