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Proceedings Paper

Wavelet analysis of wave propagation in shells with periodic stiffeners
Author(s): Massimo Ruzzene; Zheng Gu; Amr M. Baz
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Paper Abstract

The propagation of waves in cylindrical shells with periodic stiffening rings is analyzed by detecting transient waveforms of longitudinal impulse waves. The detected signals are analyzed in time-frequency domain using the Wavelet Transform. A Spectral Finite Element model is developed to predict structural response and wave dynamics of stiffened shells. The model employs spectral shape functions that accurately replicate the shell's dynamic behavior. Hence, a significantly small number of spectral elements can be used for studying the wave propagation along the structure. The model together with a Fast Fourier Transform algorithm is utilized to predict the shell response in the time domain. The analysis of the transient waveforms in the time domain shows that the stiffening rings partly reflect the propagating impulse. The reflected waveforms interact with the applied impulse and generate a constructive/destructive interference pattern, which produces pass/stop frequency bands typical of periodic structures. The filtering capabilities of periodically stiffened shells are visualized by analyzing the shell axial response using the Wavelet Transform. The Wavelet Transform indicates the location of the stop and pass bands and demonstrates that the filtering capabilities of the shell are enhanced by increasing the number of the stiffening rings. The conclusions of the numerical simulations are confirmed experimentally. Close agreement is achieved between the theoretical predictions and the experimental results. The presented theoretical and experimental techniques serve as effective means for the design of periodically stiffened shells with desirable filtering characteristics.

Paper Details

Date Published: 16 August 2001
PDF: 21 pages
Proc. SPIE 4327, Smart Structures and Materials 2001: Smart Structures and Integrated Systems, (16 August 2001); doi: 10.1117/12.436566
Show Author Affiliations
Massimo Ruzzene, Catholic Univ. of America (United States)
Zheng Gu, Univ. of Maryland/College Park (United States)
Amr M. Baz, Univ. of Maryland/College Park (United States)

Published in SPIE Proceedings Vol. 4327:
Smart Structures and Materials 2001: Smart Structures and Integrated Systems
L. Porter Davis, Editor(s)

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