Showing papers on "Constrained-layer damping published in 2003"

Active constrained-layer damping: A state-of-the-art review:

Abstract: In this paper the authors discuss the progress that has been made over the past decade in active constrained-layer damping (ACLD). ACLD treatments combine the best features of passive and active control of structural vibrations. By way of introduction the paper describes well-established techniques for passive control of structural vibrations and noise. A concise discussion of the development of so-called ‘smart’ (or ‘intelligent’) actuators and sensors and the emergence of suitable control algorithms show how passive techniques were extended to produce ACLD. A comprehensive literature review follows. It is shown how the passive and active components of ACLD complement each other to enable control of both high and low frequency modes of vibration. The active elements allow structures to adapt to suit a changing environment while the passive elements provide a fail-safe mechanism. Because of the available technology, these benefits are available without significant penalties in terms of cost, weigh...

Design of Constrained Layer Damping Topologies

Abstract: The aim of this research is to determine the optimal topologies for viscoelastic lamina used for vibration damping. The optimization objective is to maximize the system loss factor for the first resonance frequency of a base structure. Previous optimal design studies examining viscoelastic lamina have been size or shape optimization studies, assuming a certain topology for the damping treatment. In this study, the topology is optimized to maximize vibration damping levels. The loss factor is computed using the Modal Strain Energy method in the optimization process. For the initial and optimal topologies, the loss factor results are validated by using the half-power bandwidth method, which requires obtaining the forced response of the structure. The ABAQUS finite element code is used to model the structure with two-dimensional, plane stress, continuum elements. The optimization code uses a Sequential Quadratic Programming algorithm. This study extends the results of a previous study by Lumsdaine (2002) by examining the effects of a number of parameters on the optimal damping levels and the optimal topologies. The parameters examined include the total elastic and viscoelastic material fractions and the base beam thickness. Results show that significant improvements in damping performance, over 300% in some cases, are obtained by optimizing the constrained damping layer topology.© 2003 ASME

Axial Passive Damping Testing of Mass-Produced Stress Coupled, Cocured Damped Composites

Abstract: Lightweight, dynamically stiff composite structures with in-plane damping levels one and one-half to four times greater than the control panels have been demonstrated. The structures were also compared to analytical designs using the constrained layer damping theory. The structures are created using viscoelastic material sandwiched between orthotropic composite layers. The composite layers have different orientation angles, purposefully unsymmetric. Stress coupling between the stiffness layers when excited by in-plane and/or out-of-plane vibrations produces hysteresis losses that are distributed throughout the viscoelastic layers, resulting in vibrational damping with weight savings over the constrained layer damping, free-layer treatment, and various active damping approaches. Previous testing has shown that these structures improve damping. Commercial scale production of the desired fiber patterned material has not been available. It was determined that modification of a weaving process could produce a product with the patterns shown to be effective by earlier testing and analysis.

System utilizing constrained layer damping material for control of rotational vibration

Abstract: An apparatus comprises an electronic device with a device chassis. The electronic device further has a drive mounted in the device chassis. A constrained layer damping material is connected to the electronic device in a manner to control rotational vibration initiated by the drive.

Hybrid Vibration Control of Smart Laminated Composite Beams using Piezoelectric and Viscoelastic Material

Abstract: Active control of flexural vibrations of smart laminated composite beams has been carried out using piezoceramic sensor/actuator and viscoelastic material. The beams with passive constrained layer damping hale been analyzed by formulating the equations of motion through the use of extended Hamilton's principle. The dynamic characteristics such as damping ratio and modal damping of the beam are calculated for various fiber orientations by means of iterative complex eigensolution method. This paper addresses a design strategy of laminated composite under flexural vibrations to design structure with maximum possible damping capacity.

Active/Passive Control of Sound Radiation from Panels using Constrained Layer Damping

Abstract: A hybrid passive/active noise control system utilizing constrained layer damping and model predictive feedback control is presented. This system is used to control the sound radiation of panels due to broadband disturbances. To facilitate the hybrid system design, a methodology for placement of constrained layer damping which targets selected modes based on their relative radiated sound power is developed. The placement methodology is utilized to determine two constrained layer damping configurations for experimental evaluation of a hybrid system. The first configuration targets the (4,1) panel mode which is not controllable by the piezoelectric control actuator, and the (2,3) and (5,2) panel modes. The second configuration targets the (1,1) and (3,1) modes. The experimental results demonstrate the improved reduction of radiated sound power using the hybrid passive/active control system as compared to the active control system alone.

Recent advances in active constrained layer damping treatment

Abstract: It is becoming increasingly important to add damping to structures for vibration and noise control purposes. Most damping falls in two categories: passive damping and active damping. Recently, a new subset of damping was created by combining passive and active damping, thereby producing a hybrid damping treatment. This paper is a review of these damping treatments including the recent advances in the hybrid damping using active constrained layer damping (ACLD) treatment.

Optimization of Passive Constrained Layer Damping Treatments for Vibration Control of Cylindrical Shells

Abstract: passive constrained layer damping (PCLD) treatment for vibration control of cylindrical shells under a broadband force excitation. The equations governing the vibration responses are derived using the energy approach and assumed-mode method. These equations provided relationship between the integrated displacement response over the whole structural volume, i.e. the structural volume displacement (SVD), of a cylindrical shell to structural parameters of base structure and multiple PCLD patches, Genetic algorithms (GAs) based penalty function method is employed to find the optimal layout of rectangular PCLD patches with minimize the maximum displacement response of PCLD-treated cylindrical shells. Optimization solutions of PCLD patches' locations and shape are obtained under the constraint of total amount of PCLD in terms of percentage added weight to the base structure. Examination of the optimal layouts reveals that the patches tend to increase their coverage in the axial direction and distribute over the whole surface of the cylindrical shell for optimal control of the structural volume displacement.

Constrained layer damping system

Abstract: A constrained layer damping system that reduces noise and electro-magnetic interference emitted from an engine. The constrained layer damping system comprises a wiring harness (22) coated with an encapsulant; a first layer (14) of formed material on a first side of the wiring harness (22); and a second layer (28) of formed material attached to a second side of the wiring harness (22) such that the wiring harness is between the first and the second layers (14,28). A wiring harness (22) may extend from a control module (12), with the first layer (14) of formed material being on a first side of the control module (12) and the second layer (28) of formed material being on a second side of the control module (12). The constrained layer damping system permits a powertrain control module to be mounted on an air intake manifold plenum cover (14) without being negatively affected by noise, vibration, or electro-magnetic interference from the engine.

Dynamic analysis of a flexible manipulator with passive constrained layer damping

Abstract: This paper studies the vibration behavior of a flexible manipulator with passive constrained layer damping (PCLD) treatment. The manipulator rotates in a vertical plane and carries an end mass. Due to the highly nonlinear and coupled characteristics of the beam with PCLD treatment, “relative description” method is used to define the motions of the manipulator system. Using Lagrange’s equation and Rayleigh-Ritz method, the dynamic model of the manipulator is obtained and its vibration response is analyzed in the time domain. By assuming finite element shape functions as the displacement shape functions and using the complex damping model for the visco-elastic material (VEM) layer, the number of degrees of freedom of the system or the model dimension is greatly reduced. Numerical simulations show that the VEM not only reduces the amplitude of the elastic deflection but also quickly attenuates the vibration to zero. Also, it is confirmed that the geometry and physical properties of the PCLD treatment have significant effects on the dynamic response of the manipulator.Copyright © 2003 by ASME

Optimal Design and Control of a Rotating Flexible Arm With ACLD Treatment

Abstract: In this paper, the optimal design and control of a rotating clamped-free flexible arm with fully covered active constrained layer damping (ACLD) treatment are studied. The arm is rotating in a horizontal plane in which the gravitational effect and rotary inertia are neglected. The piezo-sensor voltage is fed back to the piezo-actuator via a PD controller. Finite element method (FEM) in conjunction with Hamilton’s principle is used to derive the governing equations of motion of the system which takes into account the effects of centrifugal stiffening due to the rotation of the beam. The damping behavior of the viscoelastic material (VEM) is modeled using the complex shear modulus method. The design optimization objective is to maximize the sum of the first three open-loop modal damping ratios divided by the weight of the damping treatment. A genetic algorithm, differential evolution (DE), combined with a gradient-based algorithm, sequential quadratic programming (SQP), is used to determine the optimal design variables such as the thickness and storage shear modulus of the VEM core. Next for the determined optimal design variables, the optimal control problem is performed to determine the optimal control gains which minimize a quadratic performance index. The control performance index is normalized with respect to the initial conditions and the optimal control problem is posed to solve a min-max optimization problem. The results of this study will be useful in the optimal design and control of adaptive and smart rotating structures such as rotorcraft blades or robotic arms.© 2003 ASME

Location and coverage of enhanced self-sensing piezoelectric actuators for active-passive hybrid vibration control of beam structures

Abstract: The loss factors of a simply supported beam with an enhanced active constrained layer damping treatment (EACL) are derived by the extended Hamilton principle and Rayleigh-Ritz method while open-loop and closed-loop control systems are considered. The vibration damping characteristics for the systems with partially covered active constrained layer damping and EACL treatments, are compared. The effects of location and coverage of the self-sensing piezoelectric actuators on the system performance are studied, considering active and passive actions. The results show that the location and coverage of the actuators have significant influence on system loss factors and the corresponding physical insights are discussed.