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Optimization of a Structural Acoustic Black Hole Embedded in a Stringer Stiffened Composite Laminate Panel

Author
Moorhouse, Anna
Published
[University Park, Pennsylvania] : Pennsylvania State University, 2023.
Physical Description
1 electronic document
Additional Creators
Beck, Benjamin S. and Shepherd, Micah R. (Micah Raymond), 1981-
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Open Access.
Summary
Many modern airframes utilize carbon fiber laminates to create lightweight structures that are mechanically strong and stiff. This material has a high stiffness-to-mass ratio which allows lightweight structures to maintain structural integrity. However, when driven by gearboxes present in rotorcraft these material radiate unhealthy levels of noise into the cabin. This work looks at the design and performance of structural Acoustic Black Holes (ABH) as a passive vibration attenuation solution for a common stringer-stiffened composite panel. The structural ABH is a taper in a beam or plate which follows a power law, and has been shown to attenuate incident flexural waves with little to no reflection. A parameter study systematically compares the behavior of aluminum and composite stiffened panels with varying ABH dimensions to observe the general effect of the stiffener attachment and its effect on the base plate. A multi-objective evolutionary algorithm is employed to search for the optimal ABH panel design in a novel design space. The metrics used to optimize designs are linear density, first linear buckling mode, and the forced mobility response. These metrics allow for optimization of the mass, loadbearing, and vibration response of the stiffener designs, respectfully. These numerical results predict the ability for stiffeners with a deeper ABH and greater viscoelastic treatment to have greater plate vibration attenuation. Three panel designs were manufactured, two preliminary and one optimized design. Results of experimental modal testing show the ability of the optimized ABH to perform better as a passive vibration damper in a system with structural constraints than the preliminary designs. Tests comparing a non-tapered stiffener with equivalent damping to the optimized design confirm that the ABH taper induces greater attenuation.
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Dissertation Note
M.S. Pennsylvania State University 2023.
Technical Details
The full text of the dissertation is available as an Adobe Acrobat .pdf file ; Adobe Acrobat Reader required to view the file.
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