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Showing papers on "Constrained-layer damping published in 2006"


Journal ArticleDOI
TL;DR: In this paper, a micromechanics model has been derived to predict the effective elastic and piezoelectric coefficients of the composite material used for the distributed actuator of smart structures.
Abstract: This paper deals with the analysis of vertically reinforced 1–3 piezoelectric composite materials as the material used for the distributed actuator of smart structures A micromechanics model has been derived to predict the effective elastic and piezoelectric coefficients of these piezoelectric composites which are useful for the analysis of smart beams In order to investigate the performance of a layer of this 1–3 piezoelectric composite material as the distributed actuator of smart structures, active constrained layer damping (ACLD) of smart laminated composite beams has been studied The constraining layer in the ACLD treatment has been considered to be made of this piezoelectric composite A finite element model has been developed to study the dynamics of the overall beam/ACLD system Both in-plane and out-of-plane actuations of the constraining layer of the ACLD treatment have been utilized for deriving the finite element model It has been found that these vertically reinforced 1–3 piezoelectric composite materials which are in general being used as distributed sensors can be potentially used as distributed actuators of smart structures

80 citations


Journal ArticleDOI
TL;DR: In this article, the authors provide the basic guidelines to design periodic structures with smart materials to achieve desired filtering characteristics and evaluate the behavior of the periodic structure at different length ratios and base beam materials.

55 citations


Journal ArticleDOI
TL;DR: In this paper, the analytical formulation and finite element modelling of arbitrary active constrained layer damping (ACLD) treatments applied to beams is discussed. But the authors focus on the partial layerwise theory to define the displacement field of beams with an arbitrary number of elastic, viscoelastic and piezoelectric layers attached to both surfaces.

45 citations


Journal ArticleDOI
TL;DR: A combination of wheel shape and damping optimization leads to the conclusion that a reduction in the wheel component of A-weighted rolling noise can be achieved if a simultaneous increase in wheel mass of 14 kg is accepted.

35 citations


Journal ArticleDOI
TL;DR: In this article, a two-step reduction method is proposed to reduce the dimension of the resulting augmented model, where the first reduction is applied to the second-order model, through a projection of the dissipative modes onto the structural modes.
Abstract: For a growing number of applications, the well-known passive viscoelastic constrained layer damping treatments need to be augmented by some active control technique. However, active controllers generally require time-domain modeling and are very sensitive to system changes while viscoelastic materials properties are highly frequency dependent. Hence, effective methods for time-domain modeling of viscoelastic damping are needed. This can be achieved through internal variables methods, such as the anelastic displacements fields and the Golla-Hughes-McTavish. Unfortunately, they increase considerably the order of the model as they add dissipative degrees of freedom to the system. Therefore, the dimension of the resulting augmented model must be reduced. Several researchers have presented successful methods to reduce the state space coupled system, resulting from a finite element structural model combined with an internal variables viscoelastic model. The present work presents an alternative two-step reduction method for such problems. The first reduction is applied to the second-order model, through a projection of the dissipative modes onto the structural modes. It is then followed by a second reduction applied to the resulting coupled state space model. The reduced-order models are compared in terms of performance and computational efficiency for a cantilever beam with a passive constrained layer damping treatment. Results show a reduction of up to 67% of added dissipative degrees of freedom at the first reduction step leading to much faster computations at the second reduction step. DOI: 10.1115/1.2202155

34 citations


Journal ArticleDOI
TL;DR: In this article, a comparison of optimization algorithms for constrained layer damping (CLD) patches' layout with an objective to minimize the maximum vibration response of the odd modes, which constitutes the dominant acoustic radiation, of a simply supported beam excited by a harmonic transverse force is presented.
Abstract: This paper presents a comparison of optimization algorithms for constrained layer damping (CLD) patches’ layout with an objective to minimize the maximum vibration response of the odd modes, which constitutes the dominant acoustic radiation, of a simply supported beam excited by a harmonic transverse force. An analytical model developed for relating the displacement response of the beam with bonded CLD patches and their layout is adopted to formulate the optimization problem. Four different nonlinear optimization methods/algorithms, sub-problem approximation method, the first-order method, sequential quadratic programming (SQP) and genetic algorithm (GA), are then, respectively, used to optimize the CLD patches’ locations and lengths with the aim of minimum displacement amplitude at the middle beam. The efficiency of each considered optimization method is evaluated and also compared in terms of obtained optimal beam displacement and the added weight owing to damping treatment. The results show that GA is most efficient in obtaining the best optimum for this optimization problem in spite of highest computation efforts required to improve its stability.

33 citations


Journal ArticleDOI
TL;DR: In this paper, an analytical approach for vibration damping analysis of beams with partial passive constrained layer damping (PCLD) treatments is extended to the case where the structure is covered by multiple patches.

22 citations


Journal ArticleDOI
TL;DR: Investigation of active, constrained layer damping (ACLD) of smart, functionally graded (FG) plates revealed that the active patches of ACLD treatment significantly improve the damping characteristics of the FG plates over the passive damping.
Abstract: This paper deals with the investigation of active, constrained layer damping (ACLD) of smart, functionally graded (FG) plates. The constraining layer of the ACLD treatment is considered to be made of a piezoelectric, fiber-reinforced composite (PFRC) material with enhanced effective piezoelectric coefficient that quantifies the in-plane actuating force due to the electric field applied across the thickness of the layer. The Young's modulus and the mass density of the FG plates are assumed to vary exponentially along the thickness of the plate, and the Poisson's ratio is assumed to be constant over the domain of the plate. A finite-element model has been developed to model the open-loop and closed-loop dynamics of the FG plates integrated with two patches of ACLD treatment. The frequency response of the plates revealed that the active patches of ACLD treatment significantly improve the damping characteristics of the FG plates over the passive damping. Emphasis has been placed on investigating the effect of variation of piezoelectric fiber angle in the constraining layer of the ACLD treatment on the attenuating capability of the patches. The analysis also revealed that the activated patches of the ACLD treatment are more effective in controlling the vibrations of FG plates when the patches are attached to the surface of the FG plates with minimum stiffness than when they are attached to the surface of the same with maximum stiffness

21 citations


PatentDOI
TL;DR: In this article, a low-profile, multi-axis, highly passively damped, vibration isolation mount which when used in multiplicity provides a complete vibration load isolation mounting system is presented.
Abstract: The invention disclosed is a low-profile, multi-axis, highly passively damped, vibration isolation mount which when used in multiplicity provides a complete vibration load isolation mounting system. The device provides in unique fashion a very low profile interface in combination with independently determinable compliance in all directions of vibration loading. Substantial passive damping is afforded without sacrifice to strength and linearity of behavior through adaptation of a shear wall type constrained layer damping. The result is a highly passively damped vibration isolation device that provides a very low profile interface, wide ranging longitudinal and lateral compliance management, in a durable, reliable, lightweight, and compact form.

13 citations


Journal ArticleDOI
TL;DR: In this article, a mathematical model based on Timoshenko beam assumption for a rotating cylindrical shaft with constrained layer damping treatment is developed, which is applied to study the effect of some geometric and material parameters on the flexural stiffness and damping of the shaft.
Abstract: A mathematical model, based on Timoshenko beam assumption, for a rotating cylindrical shaft with cylindrical constrained layer damping treatment is developed. The model is developed for a shaft made of composite materials, and treated with a cylindrical constrained layer damping partially covering the length span of the shaft. The discrete equations of motion are developed using two methods: the finite element method and the assumed mode method. The developed equations are applied to study the effect of some geometric and material parameters on the flexural stiffness and damping of the shaft, with emphasis on the coverage length of the cylindrical constrained layer treatment. The effect of the spinning speed is also considered. Initial results indicate that, for the special case covered in this paper, the finite element method renders accurateresults, whiletheassumed modemethod engenderserroneous results. Theresults, in general, conclude that the partial cylindrical constrained layer damping treatment, suggested in this paper, is not promising.

12 citations


Journal ArticleDOI
TL;DR: In this article, the authors used the multi-objective genetic algorithm (MOGA) to solve an integrated optimization problem of a rotating flexible arm with active constrained layer damping (ACLD) treatment.
Abstract: This paper describes the use of the multi-objective genetic algorithm (MOGA) to solve an integrated optimization problem of a rotating flexible arm with active constrained layer damping (ACLD) treatment. The arm is rotating in a horizontal plane with triangular velocity profiles. The ACLD patch is placed at the clamped end of the arm. The design objectives are to minimize the total treatment weight, the control voltage and the tip displacement of the arm, as well as to maximize the passive damping characteristic of the arm. Design variables include the control gains, the maximum angular velocity, the shear modulus of the viscoelastic layer, the thickness of the piezoelectric constraining and viscoelastic layers, and the length of the ACLD patch. In order to evaluate the effect of different combinations of design variables on the system, the finite element method, in conjunction with the Golla?Hughes?McTavish (GHM) method, is employed to model the flexible arm with ACLD treatment to predict its dynamic behavior, in which the effects of centrifugal stiffening due to the rotation of flexible arm are taken into account. As a result of optimization, reasonable Pareto solutions are successfully obtained. It is shown that the MOGA is applicable to the present integrated optimization problem.

Patent
30 Jun 2006
TL;DR: A constrained layer damping arrangement comprises a component 2, for example a vane of a gas turbine engine, a viscoelastic layer 4 and a constraining layer 6 as discussed by the authors.
Abstract: A constrained layer damping arrangement comprises a component 2, for example a vane of a gas turbine engine, a viscoelastic layer 4 and a constraining layer 6. The viscoelastic layer 4 comprises two different viscoelastic materials disposed in different regions of the viscoelastic layer 4. The different viscoelastic materials 8, 10 reach their maximum loss factors at different temperatures, so that the damping effectiveness of the combined layer 4 extends over a relatively wide temperature range.

Journal ArticleDOI
TL;DR: Based on full layerwise displacement shell theory, the vibration and damping characteristics of cylindrical sandwiched panels with viscoelastic layers are investigated in this article, where the transverse shear deformation and the normal strain of the hybrid panels are fully taken into account for the structural damping modeling.
Abstract: 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.

01 Jan 2006
TL;DR: In this article, the constrained damping layer (CLD), which was arranged on the outer surface of the structure components, was adopted as a means of suppressing the vibration, and the maximum vibration amplitude of the satellite has been decreased 22.3% in the 0.1g level vibration test, which is acceptable for the launch.
Abstract: In the final check-and-accept level test,the vibration of a payload bracket in a satellite failed to be qualified for the launch.Without redesigning and changing the original structure,the constrained damping layer(CLD),which was arranged on the outer surface of the structure components,was adopted as a means of suppressing the vibration.In the design procedure of the CLD,the technique of finite element analysis was used for selecting the project,which includes the thickness of damping layer and constrained layer and the position of arrangement.Then with all factors considered,such as damping ratio and additional mass,a rational project of constrained damping layer is gained.After first tested in a tested satellite to confirm the final CDL project,the CLD project was performed on the final-model satellite.With this treatment,the maximum vibration amplitude of the satellite has been decreased 22.3% in the 0.1g level vibration test,which is acceptable for the launch.The satellite was launch successfully and has been working normally in the orbit since then.The technique and the procedure of design provide valuable experience for treating similar problems in the future.


Proceedings ArticleDOI
16 Mar 2006
TL;DR: In this article, a finite element model of the stand-off layer constrained damping treatment is developed, which accounts for the geometrical and physical parameters of the slotted SOL, the viscoelastic, layer the constraining layer, and the base structure.
Abstract: Damping treatments with stand-off layer (SOL) have been widely accepted as an attractive alternative to conventional constrained layer damping (CLD) treatments. Such an acceptance stems from the fact that the SOL, which is simply a slotted spacer layer sandwiched between the viscoelastic layer and the base structure, acts as a strain magnifier that considerably amplifies the shear strain and hence the energy dissipation characteristics of the viscoelastic layer. Accordingly, more effective vibration suppression can be achieved by using SOL as compared to employing CLD. In this paper, a comprehensive finite element model of the stand-off layer constrained damping treatment is developed. The model accounts for the geometrical and physical parameters of the slotted SOL, the viscoelastic, layer the constraining layer, and the base structure. The predictions of the model are validated against the predictions of a distributed transfer function model and a model built using a commercial finite element code (ANSYS). Furthermore, the theoretical predictions are validated experimentally for passive SOL treatments of different configurations. The obtained results indicate a close agreement between theory and experiments. Furthermore, the obtained results demonstrate the effectiveness of the CLD with SOL in enhancing the energy dissipation as compared to the conventional CLD. Extension of the proposed one-dimensional CLD with SOL to more complex structures is a natural extension to the present study.

Proceedings ArticleDOI
17 Mar 2006
TL;DR: In this article, the theory governing the vibration of beams treated with CLD, that has functionally graded viscoelastic cores, was presented using the finite element method (FEM), and the predictions of the FEM were validated experimentally for plain beams, beams, and beams with conventional CLD/FGVEM of different configurations.
Abstract: Conventionally, the viscoelastic cores of Constrained Layer Damping (CLD) treatments are made of materials that have uniform shear modulus. Under such conditions, it is well-recognized that these treatments are only effective near their edges where the shear strains attain their highest values. In order to enhance the damping characteristics of the CLD treatments, we propose to manufacture the cores from Functionally Graded ViscoElastic Materials (FGVEM) that have optimally selected gradient of the shear modulus over the length of the treatments. With such optimized distribution of the shear modulus, the shear strain can be enhanced, and the energy dissipation can be maximized. The theory governing the vibration of beams treated with CLD, that has functionally graded viscoelastic cores, is presented using the finite element method (FEM). The predictions of the FEM are validated experimentally for plain beams, beams treated conventional CLD, and beams with CLD/FGVEM of different configurations. The obtained results indicate a close agreement between theory and experiments. Furthermore, the obtained results demonstrate the effectiveness of the new class of CLD with functionally graded cores in enhancing the energy dissipation over the conventional CLD over a broad frequency band. Extension of the proposed one-dimensional beam/CLD/FGVEM system to more complex structures is a natural extension to the present study.

Proceedings ArticleDOI
01 May 2006
TL;DR: In this article, a new analytical power input method is proposed for evaluating the loss factor of built-up structures, based on the finite element model with assigned properties of the con stituents.
Abstract: The Power Input Method (PIM) is used both experimentally and a nalytically to estimate the system loss factor for sandwich panels with various configurations of Constrained Layer Damping (CLD) treatments over a broad frequency range. The experimental power input method is applied to both uniformly and non -uniformly da mped structures. Results are compared with results from other experimental methods. A new analytical power input method is proposed for evaluating the loss factor of built -up structures, based on the finite element model with assigned properties of the con stituents. The new analytical power input method is evaluated by comparison with the commonly used Modal Strain Energy (MSE) method. Instead of making an approximate correction of the constant material properties, this analytical power input method directl y takes into account the frequency -dependent material properties of the viscoelastic material using the MSC/NASTRAN direct frequency response solution. Results of experimental and analytical methods are presented, compared and discussed. It is shown that: 1) all three currently available experimental methods yield consistent results, while the power input method gives damping estimation other than just at several discrete frequencies basically in the low frequency range; 2) both the analytical power input m ethod and the modal strain energy method yield consistent results with the experimental power input method. Furthermore, both experimental and analytical power input methods are used to investigate how loss factors change as the excitation position change. This shows another merit of the analytical power input method, because analytical modal methods cannot take into account the change of excitation position.

Journal ArticleDOI
TL;DR: Bochkareva et al. as mentioned in this paper investigated multilayered metal-polymer-ceramic damping coatings and their FEMbased computer modeling that can provide an alternative spacer material in a constrained layer damping configuration so as to enable design of three and more layered damping structures, but with controlled structure and mechanical properties of the gradient damping layers.
Abstract: The focus of this paper is directed toward the investigation into multilayered metal‐polymer‐ceramic damping coatings and their FEM‐based computer modeling that can provide an alternative spacer material in a constrained layer damping configuration so as to enable design of three and more layered damping structures, but with controlled structure and mechanical properties of the gradient damping layers. An advanced measuring system for the analysis of vibrating structures is based on a laser scanning vibration interferometer. The position of a ceramic layer in a constrained layer configuration does matter. The outward position is most favorable for high strength by ceramic layer and damping by constrained aluminum‐polymer layer. Modal loss factors obtained in the 60%–80% partial‐coverage test cases of cylindrical shell are higher than the maximum modal damping obtained in the case of 100% coverage. The modal damping for the target modes is higher than in the complete‐coverage case. An effective damping design involves selecting a proper combination of area coverage, relative thickness and stiffness values of the layers of the damped configuration. [Dr. Bochkareva is currently continuing her research work under 2‐year EU INTAS 2005‐2007 postdoctoral fellowship Ref. No. 04‐83‐3067.]