Bending-torsional Stability and Vibrations of Beams Conveying Pulsating Flow in the Presence of Free Stream

Askarian, Abdolreza | 2017

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 49774 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Haddadpour, Hassan; Dehghani Firouzabadi, Rohollah
  7. Abstract:
  8. In the current study, stability and nonlinear vibration of bending-torsional extensible beams conveying internal pulsatile and uniform external flow are studied. The internal and external fluid flows are assumed to be incompressible and frictionless. Applying the extensibility to the pipe along its length and using the nonlinear Euler-Bernoulli beam model and including some appropriate additional assumptions, the 3D nonlinear equations of motion of a cantilevered composite pipe is obtained. In order to derive the equations governing the fluid-structure interaction, the internal flow effect is modeled as a distributed load along the pipe which contains the inertia, Coriolis and centrifugal forces. The external flow is in the subsonic regime and can be modeled using the unsteady Wagner aerodynamic relations, with the Jones approximation. The derived governing partial differential equations of the coupled bending–torsional vibrations of the extensible pipe are obtained using extended Hamilton’s principle and then discretized via the Galerkin approach. The standard eigen-value analysis and the Floquet theory are applied to obtain the stability boundaries of the system for both the steady and pulsatile internal fluid flow. Additionally, adaptive time step Adams-Moulton algorithm is applied to extract the response time history, bifurcation, FFT-PSD and phase plane plots, numerically. Comprehensive verifications for the free vibrations of the coupled-field problem with internal and external flows are studied. Eventually, stability analysis and response time history for a variety of test cases with steady/pulsatile internal flow, homogenous/composite structural model for both 2D and 3D vibrations are reported and many useful conclusions are drawn
  9. Keywords:
  10. Bending-Torsion Coupling ; Floquet Eigenfunctions ; Nonlinear Vibration ; Wagner Method ; Unsteady Aerodynamic ; Extensible Pipe ; Pulsatile Flow

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