Optimum placement and control of active constrained layer damping using the modal strain energy approach

1998 ◽  
Author(s):  
Jeng-Jong Ro ◽  
Amr M. Baz
Keyword(s):  
Strain Energy ◽  
Energy Approach ◽  
Constrained Layer Damping ◽  
Modal Strain Energy ◽  
Optimum Placement ◽  
Active Constrained Layer Damping ◽  
And Control ◽  
Active Constrained Layer

Optimum Placement and Control of Active Constrained Layer Damping using Modal Strain Energy Approach

2002 ◽  
Vol 8 (6) ◽  
pp. 861-876 ◽  
Author(s):  
J. Ro ◽  
A. Baz
Keyword(s):  
Strain Energy ◽  
High Efficiency ◽  
Effective Means ◽  
Optimization Technique ◽  
Optimal Placement ◽  
Constrained Layer Damping ◽  
Modal Strain Energy ◽  
Damping Characteristics ◽  
Active Constrained Layer Damping ◽  
Active Constrained Layer

The Active Constrained Layer Damping (ACLD) treatment has been used successfully for controlling the vibration of various flexible structures. It provides an effective means for augmenting the simplicity and reliability of passive damping with the low weight and high efficiency of active controls to attain high damping characteristics over broad frequency bands. In this paper, optimal placement strategies of ACLD patches are devised using the modal strain energy (MSE) method. These strategies aim at minimizing the total weight of the damping treatments while satisfying constraints imposed on the modal damping ratios. A finite element model is developed to determine the modal strain energies of plates treated with ACLD. The treatment is then applied to the elements that have highest MSE in order to target specific modes of vibrations. Numerical examples are presented to demonstrate the utility of the devised optimization technique as an effective tool for selecting the optimal locations of the ACLD treatment to achieve desired damping characteristics over a broad frequency band.

Optimum Design and Control of Active Constrained Layer Damping

1995 ◽  
Vol 117 (B) ◽  
pp. 135-144 ◽  
Author(s):  
A. Baz ◽  
J. Ro
Keyword(s):  
Rational Design ◽  
Broad Band ◽  
Design Parameters ◽  
Constrained Layer Damping ◽  
Wide Range ◽  
Active Constrained Layer Damping ◽  
Operating Temperatures ◽  
And Control ◽  
Passive Constrained Layer Damping ◽  
Active Constrained Layer

Conventional Passive Constrained Layer Damping (PCLD) treatments with viscoelastic cores are provided with built-in sensing and actuation capabilities to actively control and enhance their vibration damping characteristics. The design parameters and control gains of the resulting Active Constrained Layer Damping (ACLD) treatments are optimally selected, in this paper, for fully-treated beams using rational design procedures. The optimal thickness and shear modulus of the passive visco-elastic core are determined first to maximize the modal damping ratios and minimize the total weight of the damping treatment. The control gains of the ACLD are then selected using optimal control theory to minimize a weighted sum of the vibrational and control energies. The theoretical performance of beams treated with the optimally selected ACLD treatment is determined at different excitation frequencies and operating temperatures. Comparisons are made with the performance of beams treated with optimal PCLD treatments and untreated beams which are controlled only by conventional Active Controllers (AC). The results obtained emphasize the potential of the optimally designed ACLD as an effective means for providing broad-band attenuation capabilities over wide range or operating temperatures as compared to PCLD treatments.

Vibration Control of a Flexible Arm with Active Constrained Layer Damping

1997 ◽  
Vol 16 (4) ◽  
pp. 271-287 ◽  
Author(s):  
S. R. Tawfeic ◽  
A. Baz ◽  
A. A. Ismail ◽  
O. A. Azim ◽  
S. S. Karar
Keyword(s):  
Elastic Layer ◽  
Polyvinylidene Fluoride ◽  
Lateral Displacement ◽  
Flexible Manipulator ◽  
Constrained Layer Damping ◽  
Modal Strain Energy ◽  
Order Polynomial ◽  
Active Constrained Layer Damping ◽  
Active Constrained Layer ◽  
Piezo Electric

The vibration of a single link flexible manipulator is attenuated using the Active Constrained layer damping (ACLD) treatment. The ACLD treatment consists of a viscoelastic layer sandwiched between two piezo-electric layers acting as constraining layers with sensing and actuation capabilities. The shear deformation of the visco-elastic layer is controlled to enhance the energy dissipation mechanism and attenuate the vibration of the flexible manipulator. A finite element model is used to describe the dynamics of the system. A third order polynomial is used to describe the lateral displacement of the manipulator and a second order polynomial is used to describe the longitudinal displacements of the different layers of the manipulator. An appropriate control law is used to control the system. The Coupled Modal Strain energy technique is used to compute the equivalent viscous damping ratios for the elastic layer using the loss factor data of the material. The theoretical predictions of the model are compared with the experimental performance of a manipulator fully treated with a Dyad 606 visco-elastic layer sandwiched between two layers of polyvinylidene fluoride (PVDF) piezo-electric films. The results obtained clearly demonstrate the attenuation capabilities of the Actively-Controlled Constrained Layer Damping.

Optimum Design and Control of Active Constrained Layer Damping

1995 ◽  
Vol 117 (B) ◽  
pp. 135-144 ◽  
Author(s):  
A. Baz ◽  
J. Ro
Keyword(s):  
Rational Design ◽  
Broad Band ◽  
Design Parameters ◽  
Constrained Layer Damping ◽  
Wide Range ◽  
Active Constrained Layer Damping ◽  
Operating Temperatures ◽  
And Control ◽  
Passive Constrained Layer Damping ◽  
Active Constrained Layer

Conventional Passive Constrained Layer Damping (PCLD) treatments with viscoelastic cores are provided with built-in sensing and actuation capabilities to actively control and enhance their vibration damping characteristics. The design parameters and control gains of the resulting Active Constrained Layer Damping (ACLD) treatments are optimally selected, in this paper, for fully-treated beams using rational design procedures. The optimal thickness and shear modulus of the passive visco-elastic core are determined first to maximize the modal damping ratios and minimize the total weight of the damping treatment. The control gains of the ACLD are then selected using optimal control theory to minimize a weighted sum of the vibrational and control energies. The theoretical performance of beams treated with the optimally selected ACLD treatment is determined at different excitation frequencies and operating temperatures. Comparisons are made with the performance of beams treated with optimal PCLD treatments and untreated beams which are controlled only by conventional Active Controllers (AC). The results obtained emphasize the potential of the optimally designed ACLD as an effective means for providing broad-band attenuation capabilities over wide range or operating temperatures as compared to PCLD treatments.

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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