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.

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.

scholarly journals Performance Characteristics of Active Constrained Layer Damping

1995 ◽  
Vol 2 (1) ◽  
pp. 33-42 ◽  
Author(s):  
A. Baz ◽  
J. Ro
Keyword(s):  
Broad Band ◽  
Structural Response ◽  
Piezoelectric Sensor ◽  
Performance Characteristics ◽  
Constrained Layer Damping ◽  
New Class ◽  
Damping Characteristics ◽  
Active Constrained Layer Damping ◽  
Passive Constrained Layer Damping ◽  
Active Constrained Layer

Theoretical and experimental performance characteristics of the new class of actively controlled constrained layer damping (ACLD) are presented. The ACLD consists of a viscoelastic damping layer sandwiched between two layers of piezoelectric sensor and actuator. The composite ACLD when bonded to a vibrating structure acts as a “smart” treatment whose shear deformation can be controlled and tuned to the structural response in order to enhance the energy dissipation mechanism and improve the vibration damping characteristics. Particular emphasis is placed on studying the performance of ACLD treatments that are provided with sensing layers of different spatial distributions. The effect of the modal weighting characteristics of these sensing layers on the broad band attenuation of the vibration of beams fully treated with the ACLD is presented theoretically and experimentally. The effect of varying the gains of a proportional and derivative controller and the operating temperature on the ACLD performance is determined for uniform and linearly varying sensors. Comparisons with the performance of conventional passive constrained layer damping are presented also. The results obtained emphasize the importance of modally shaping the sensor and demonstrate the excellent capabilities of the ACLD.

A Computational Optimal Control Approach to the Design of a Flexible Rotating Beam With Active Constrained Layer Damping

Aerospace ◽  
2004 ◽  
Author(s):  
Y. C. E. Lee ◽  
E. H. K. Fung ◽  
J. Q. Zou ◽  
H. W. J. Lee
Keyword(s):  
Optimal Control ◽  
Coordinate System ◽  
Control Voltage ◽  
Constrained Layer Damping ◽  
Shape Functions ◽  
Control Parametrization ◽  
Highly Nonlinear ◽  
Active Constrained Layer Damping ◽  
Passive Constrained Layer Damping ◽  
Active Constrained Layer

In this paper, a computational approach is adopted to solve the optimal control and optimal parameter selection problems of a rotating flexible beam fully covered with active constrained layer damping (ACLD) treatment. The beam rotates in a vertical plane under the gravitational effect with variable angular velocity and carries an end mass. Tangent coordinate system and the moving coordinate system are used in the system modeling. Due to the highly nonlinear and coupled characteristics of the system, a relative description method is used to represent the motion of the beam and the motion equations are set up by using relative motion variables. Finite element shape functions of a cantilever beam [1] are used as the displacement shape functions in this study. Lagrangian formulation and Raleigh-Ritz approach [2] are employed to derive the governing equations of motion of the nonlinear time-varying system. The problem is posed as a continuous-time optimal control problem. The control function parameters are the control gains. The two system parameters are the thickness of the constraining layer and the viscoelastic material layer. The software package MISER3.2, which is based on the Control Parametrization and the Control Parametrization Enhancing Transform (CPET) techniques is used to solve the combined problems. The optimal solution takes the end deflection, control voltage and the total weight into account. Results show that substantial improvements are obtained with ACLD as compared to the passive constrained layer damping (PCLD) treatment.

Boundary Control of Beams Using Active Constrained Layer Damping

1997 ◽  
Vol 119 (2) ◽  
pp. 166-172 ◽  
Author(s):  
A. Baz
Keyword(s):  
Boundary Control ◽  
Distributed Parameter ◽  
Constrained Layer Damping ◽  
Damping Characteristics ◽  
Distributed Parameter Model ◽  
Active Constrained Layer Damping ◽  
Cantilevered Beams ◽  
Passive Constrained Layer Damping ◽  
Active Constrained Layer ◽  
Globally Stable

A variational mathematical model is developed using Hamilton’s principle to describe the dynamics of beams fully-treated with Active Constrained Layer Damping (ACLD) treatments. The resulting distributed-parameter model is utilized in devising a globally stable boundary control strategy which is compatible with the operating nature of the ACLD treatments. The effectiveness of the ACLD in damping out the vibration of cantilevered beams is determined for different control gains and compared with the performance of conventional Passive Constrained Layer Damping (PCLD). The results obtained demonstrate the high damping characteristics of the boundary controller particularly over broad frequency bands.

Active Constrained Layer Damping of Seismic Excitations

1995 ◽  
Author(s):  
A. Baz ◽  
S. Poh
Keyword(s):  
Sliding Mode ◽  
Effective Means ◽  
Three Dimensional ◽  
Constrained Layer Damping ◽  
Seismic Excitations ◽  
Vibrating Structures ◽  
Wide Range ◽  
Active Constrained Layer Damping ◽  
Classical Control ◽  
Active Constrained Layer

Abstract This paper aims at demonstrating the feasibility of Active Constrained Layer Dampers (ACLD) as an effective means for damping out seismic-induced vibrations of structures. The ACLD concept is motivated by the destructive effects that seismic excitations have on most of the uncontrolled structures. The effectiveness of the ACLD in enhancing the damping characteristics of conventional visco-elastic dampers is demonstrated experimentally for structures subjected to base excitations. Classical identification methods are used to identify a mathematical model that describes the interaction between the vibrating structures, the ACLD system and the seismic excitation. The model is integrated with a robust Continuous Sliding Mode (CSM) controller to reject the effect of the seismic excitations acting on vibrating structures with uncertain dynamic parameters. In this manner, the ACLD and the CSM algorithm present a simple but yet powerful alternative to classical control methods for rejecting seismic excitations and accommodating wide range of parameter uncertainty. The emphasis, in this paper, is placed on multi-story two-dimensional scaled structures which are provided with diagonal braces of the ACLD. However, the techniques developed can be readily extended to three-dimensional and larger structures.

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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