Lagrangian Formulation of Rotating Beam With Active Constrained Layer Damping in Time Domain Analysis

2004 ◽  
Vol 126 (2) ◽  
pp. 359-364 ◽  
Author(s):  
E. H. K. Fung ◽  
J. Q. Zou ◽  
H. W. J. Lee
Keyword(s):  
Elastic Material ◽  
Time Domain ◽  
Loss Factor ◽  
Degrees Of Freedom ◽  
Ritz Method ◽  
Lagrangian Formulation ◽  
Constrained Layer Damping ◽  
Rotating Beam ◽  
Active Constrained Layer Damping ◽  
Active Constrained Layer

In this paper, Lagrangian formulation of a horizontal rotating beam with active constrained layer damping (ACLD) treatment is presented. The problem is approached by the Rayleigh-Ritz method. By assuming modal functions as the displacement shape functions and using effective damping model of the visco-elastic material (VEM) layer, the number of degrees of freedom of the system is greatly reduced. The damping of the visco-elastic material is characterized by a shear (storage) modulus and a loss factor. Also the dynamic behavior of the rotating ACLD beam is analyzed in the time domain. The effects of control gains, shear modulus and loss factor of the VEM on the dynamic response are also investigated.

Active Control of Vibration and Noise Radiation from Fluid-Loaded Cylinder using Active Constrained Layer Damping

2002 ◽  
Vol 8 (6) ◽  
pp. 877-902 ◽  
Author(s):  
W. Laplante ◽  
T. Chen ◽  
A. Baz ◽  
W. Sheilds
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Acoustic Radiation ◽  
Sound Radiation ◽  
Element Model ◽  
Water Tank ◽  
Constrained Layer Damping ◽  
Active Constrained Layer Damping ◽  
Active Constrained Layer ◽  
Surrounding Fluid

Vibration and sound radiation from fluid-loaded cylindrical shells are controlled using patches of Active Constrained Layer Damping (ACLD). The performance and the enhanced damping characteristics via reduced vibrations and sound radiation in the surrounding fluid is demonstrated both theoretically and experimentally. A prime motivation for this work is the potential wide applications in submarines and torpedoes where acoustic stealth is critical to the effectiveness of missions. A finite element model is also developed to predict the vibration and the acoustic radiation in the surrounding fluid of the ACLD-treated cylinders. The developed model is used to study the effectiveness of the control and placement strategies of the ACLD in controlling the fluid-structure interactions. A water tank is constructed that incorporates test cylinders treated with two ACLD patches placed for targeting specific vibration modes. Using this arrangement, the effectiveness of different control strategies is studied when the submerged cylinders are subjected to internal excitation, and the radiated sound pressure level in the water is observed. Comparisons are made between the experimental results and the theoretical predictions to validate the finite element model.

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