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‌ Experimental Effects of Employing Dynamic Absorbers on Vibration Behavior of Civil A/C Reinforced Panel

Aeeni, Hossein | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50360 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Hosseini Kordkhaili, Ali
  7. Abstract:
  8. The aim of this project is analysis of fuselage vibration reduction on turboprop aircraft, by using passive methods. In this method by design and installation of tuned vibrant absorber (a system composed of mass and auxiliary spring) which its natural frequency is tuned, taking into account the excitation frequency of the vibrant fuselage body under harmonic force. And the motion of the point which is connected to it, would be ceased. Considering the place limitations and weight in the aircraft design, the designed absorber with respect to space and occupied volume shall be mountable on the aircraft frames and for maximum reduction of skin vibrations and eventually damping of acoustic energy should have optimum mass. Since the absorber shall be tunable in a limited frequency range, hence absorber shall be continuous in mass distribution and have variable frequency capability. The natural frequency of absorber should be 110 HZ (i.e. operational frequency of the propeller blades in the proposed aircraft) which as dominant excitation frequency in sound creation and in acoustic and vibration measurements has the main role. Compared to previous studies in this study a different trend is used. Considering the natural modes of the panel, which is under study, the natural frequency of the absorber is near to bending and twisting primary modes of the panel is chosen about 130 HZ to investigate effort on the vibration reduction of the panel in this modes. The main limitation of this project is to find the optimum arrangement for installation for the absorber on the internal body of aircraft, which is due to the weight restrictions and various support conditions, on the panels. The experimental results shown, when the absorbers installing on the specific places of the structure (the sample panel under study) the proper reduction in panel vibration can be attained.in comparison to active methods, this method is more economic and compared to another passive method in which the structure elements weights are increased, this method is more economic and imposes less weight increase on the aircraft
  9. Keywords:
  10. Noise ; Sound ; Passive Methods ; Reinforced Panel ; Dynamic Absorber ; Propeller Aircraft

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