Comparison of the mechanism and effectiveness of position and velocity feedback in active constrained-layer damping treatments

2000 ◽  
Author(s):  
Farhan Gandhi ◽  
Brian E. Munsky
Keyword(s):  
Constrained Layer Damping ◽  
Velocity Feedback ◽  
Active Constrained Layer Damping ◽  
Damping Treatments ◽  
Active Constrained Layer

Damping Characteristics of Beams with Enhanced Self-Sensing Active Constrained Layer Treatments Under Various Boundary Conditions

2004 ◽  
Vol 127 (2) ◽  
pp. 173-187 ◽  
Author(s):  
J. X. Gao ◽  
W. H. Liao
Keyword(s):  
Boundary Conditions ◽  
Careful Analysis ◽  
Constrained Layer Damping ◽  
Various Boundary Conditions ◽  
Damping Characteristics ◽  
Control Gain ◽  
Active Constrained Layer Damping ◽  
Damping Treatments ◽  
Active Constrained Layer ◽  
Loss Factors

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.

Support design of secondary mirror based on active constrained layer damping treatments

2016 ◽  
Vol 45 (11) ◽  
pp. 1118001
Author(s):  
田士涛 Tian Shitao ◽  
徐振邦 Xu Zhenbang ◽  
秦 超 Qin Chao ◽  
夏明一 Xia Mingyi ◽  
吴清文 Wu Qingwen
Keyword(s):  
Constrained Layer Damping ◽  
Support Design ◽  
Secondary Mirror ◽  
Active Constrained Layer Damping ◽  
Damping Treatments ◽  
Active Constrained Layer

Effectiveness of Active Constrained Layer Damping Treatments in Attenuating Resonant Oscillations

2002 ◽  
Vol 8 (6) ◽  
pp. 747-775 ◽  
Author(s):  
Farhan Gandhi ◽  
Brian Munsky
Keyword(s):  
Excitation Level ◽  
Viscoelastic Layer ◽  
Constrained Layer Damping ◽  
Velocity Feedback ◽  
Vibration Attenuation ◽  
Position Feedback ◽  
Active Constrained Layer Damping ◽  
Excitation Force ◽  
Viscoelastic Layers ◽  
Active Constrained Layer

This paper highlights the importance of considering the piezoelectric constraining layer voltage (or electric field) limits when evaluating the effectiveness of an active constrained layer damping treatment in attenuating resonant vibration. It is seen that, when position feedback is used, intermediate viscoelastic layer stiffness values are always optimal, and maximum allowable control gains and possible vibration attenuation progressively decrease with increasing excitation force levels. On the other hand, with velocity feedback, the optimal viscoelastic layer stiffness is dependent on the excitation level. For low excitation force amplitudes, stiff viscoelastic layers are most effective, with large velocity feedback gains producing substantial vibration attenuation without exceeding piezoelectric layer voltage limits. However, for higher excitation force levels, stiff viscoelastic layers result in excess voltages even at very small velocity feedback gains, and are unable to provide any vibration attenuation. In such a case, intermediate viscoelastic layer stiffness values are preferable, and maximum velocity feedback gains and possible vibration attenuation progressively decrease with increasing excitation level, as in the case of position feedback. For both position and velocity feedback, when excitation forces are beyond a certain level the allowable control gains are so limited that no additional damping is obtained beyond that already available through the passive treatment.

Torsional Vibration Control of a Shaft Through Active Constrained Layer Damping Treatments

1997 ◽  
Vol 119 (4) ◽  
pp. 504-511 ◽  
Author(s):  
I. Y. Shen ◽  
Weili Guo ◽  
Y. C. Pao
Keyword(s):  
Torsional Vibration ◽  
Angular Displacement ◽  
Circular Cross Section ◽  
Critical Factor ◽  
Constrained Layer Damping ◽  
Active Constrained Layer Damping ◽  
Piezoelectric Strain ◽  
Damping Treatments ◽  
Active Constrained Layer ◽  
Hybrid Damping

This paper proposes a hybrid damping design to control torsional vibration of a shaft with a circular cross section through use of actively constrained layer (ACL) damping treatments proposed by Baz (1993) and Shen (1993, 1994a). The ACL damping treatment consists of a piezoelectric constraining layer and a viscoelastic shear layer wrapping around the shaft in the form of a helix. In addition, the angular displacement of the shaft is fed back to regulate the helical motion of the piezoelectric constraining layer. The equation of motion of this design is derived, and its stability and controllability are discussed. Finally, numerical examples show that this ACL design can reduce torsional vibration of a shaft. A sensitivity analysis shows that ACL is most effective in suppressing those modes with significant torsional vibration response. Stability, in general, is not a critical factor in designing ACL systems, because the piezoelectric strain of the constraining layer at the threshold of instability is too large to occur.

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