Discontinuous constrained layer damping treatments applied to a vibrating free‐free beam.

1996 ◽  
Vol 99 (4) ◽  
pp. 2586-2603 ◽  
Author(s):  
Samir Uppal ◽  
Alison B. Flatau ◽  
Theodore B. Bailey
2000 ◽  
Vol 122 (4) ◽  
pp. 434-439 ◽  
Author(s):  
Eric M. Austin ◽  
Daniel J. Inman

It is commonplace in academia to base models of constrained-layer damping treatments on the assumption that the facesheets displace identically during transverse vibrations. This assumption is valid for a large range of problems, particularly for problems common in the era when damping was achieved by applying foil-backed treatments to thin panels. The authors show using a very simple example that oversimplified modeling can skew distributions of modal strain energy, a common indicator of damping. [S0739-3717(00)00204-X]


2006 ◽  
Vol 324-325 ◽  
pp. 699-702 ◽  
Author(s):  
Il Kwon Oh ◽  
Tai Hong Cheng

Based on full layerwise displacement shell theory, the vibration and damping characteristics of cylindrical sandwiched panels with viscoelastic layers are investigated. The transverse shear deformation and the normal strain of the cylindrical hybrid panels are fully taken into account for the structural damping modeling. The layerwise finite element model is formulated by using Hamilton’s virtual work principle and the cylindrical curvature of hybrid panels is exactly modeled. Modal loss factor and frequency response functions are analyzed for various structural parameters of cylindrical sandwich panels. Present results show that the full layerwise finite element method can accurately predict the vibration and damping characteristics of the cylindrical hybrid panels with surface damping treatments and constrained layer damping.


2004 ◽  
Vol 127 (2) ◽  
pp. 173-187 ◽  
Author(s):  
J. X. Gao ◽  
W. H. Liao

In this paper, an energy-based approach is developed to investigate damping characteristics of beams with enhanced self-sensing active constrained layer (ESACL) damping treatments. Analytical formulations for the active, passive, and total hybrid modal loss factors of the cantilever and simply-supported beams partially covered with the ESACL are derived. The analytical formulations are validated with the results in the literature and experimental data for the cantilever beam. Beams with other boundary conditions can also be solved and discussed using the presented approach. The results show that the edge elements in the ESACL can significantly improve the system damping performance as compared to the active constrained layer damping treatment. The effects of key parameters, such as control gain, edge element stiffness, location, and coverage of the ESACL patch on the system loss factors, have been investigated. It has also been shown that the boundary conditions play an important role on the damping characteristics of the beam structure with the ESACL treatment. With careful analysis on the location and coverage of the partially covered ESACL treatment, effective vibration control for beams under various boundary conditions for specific modes of interest would be achieved.


2002 ◽  
Vol 124 (4) ◽  
pp. 612-616 ◽  
Author(s):  
Yi-Chu Hsu ◽  
I. Y. Shen

This paper presents a bulk micromachining process to fabricate micro-constrained layer treatments (MCLT) on a microstructure to increase its damping, and demonstrates the damping improvement through calibrated experiments. MCLT consists of a silicon base structure (e.g., beams or plates), a viscoelastic photoresist layer, and an aluminum constraining layer. Silicon base beams and plates are fabricated from {100} wafer through Ethylene-Diamine-Pyrocatechol etch and buffered oxide etch. A 4.5-μm thick photoresist AZ4620 is spun on the silicon base beam as the viscoelastic layer. Finally, an aluminum layer is deposited through low-pressure vapor deposition as the constraining layer. To evaluate damping performance of MCLT, silicon beams with and without MCLT are subjected to swept-sine excitations by PZT from 0 to 100 kHz. In addition, a laser Doppler vibrometer and a spectrum analyzer measured frequency response functions (FRF) of the specimen. A finite element analysis identifies the resonance modes measured in FRF. Experimental results confirm that MCLT can increase damping of silicon beams by at least 40%. Significantly better damping performance is expected, if the loss factor of the viscoelastic layer is increased.


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