Showing papers on "Constrained-layer damping published in 2012"

Active constrained layer damping of smart laminated composite sandwich plates using 1–3 piezoelectric composites

Abstract: This paper deals with the analysis of active constrained layer damping (ACLD) of sandwich plate with laminated composite faces. The constraining layer of the ACLD treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composites. Several honeycomb core materials like HEREX honeycomb and honeycomb with foam fill separated by different facing materials have been studied and a three-dimensional finite element model has been developed considering first order shear deformation theory individually for each layer of the sandwich plate. The effect of the ratio between the face sheet thickness and the core thickness of the sandwich plate on the frequency response has been studied. Particular emphasis has been placed on investigating the effect of the variation of piezoelectric fiber orientation angle on the performance of the ACLD treatment.

Sole structure with alternating spring and damping layers

Abstract: A sole structure may include multiple macrolayers. Each of those macrolayers may include a spring plate and a layer of damping material. Macrolayers may be bonded or otherwise fixed relative to one another and provide constrained layer damping in response to impact forces occurring as a result of activity of a wearer of an article of footwear incorporating the sole structure.

Active constrained layer damping of geometrically nonlinear vibrations of smart laminated composite sandwich plates using 1–3 piezoelectric composites

Abstract: This paper deals with the analysis of active constrained layer damping (ACLD) of geometrically nonlinear vibrations of sandwich plate with orthotropic laminated composite faces separated by a flexible core. The constraining layer of the ACLD treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composites. The Golla–Hughes–McTavish method has been implemented to model the constrained viscoelastic layer of the ACLD treatment in time domain. The first-order shear deformation theory and the Von Karman type nonlinear strain displacement relations are used for analyzing this coupled electro-elastic problem. A three dimensional finite element model of smart laminated composite sandwich plate integrated with ACLD patches has been developed to investigate the performance of these patches for controlling the geometrically nonlinear vibrations of the plates. The numerical results indicate that the ACLD patches significantly improve the damping characteristics of the sandwich plates with laminated cross-ply and angle-ply facings for suppressing their geometrically nonlinear vibrations. Particular emphasis has been placed on investigating the effect of the variation of piezoelectric fiber orientation angle on the performance of the ACLD treatment.

Active control of laminated composite truncated conical shells using vertically and obliquely reinforced 1-3 piezoelectric composites

Abstract: This paper deals with the analysis of active control of vibration of thin laminated composite truncated circular conical shells using vertically and obliquely reinforced 1-3 piezoelectric composite (PZC) materials as the constraining layer of the active constrained layer damping (ACLD) treatment. A finite element model of smart truncated conical laminated shells integrated with the patches of such ACLD treatment has been developed to demonstrate the performance of these patches on enhancing the damping characteristics of thin symmetric and antisymmetric cross-ply and antisymmetric angle-ply laminated truncated conical shells. Velocity feedback control loop has been implemented to activate the patches. The effect of variation of semi-cone angle on the performance of the patches for controlling first few modes of the truncated conical laminated shells has been demonstrated. Emphasis has also been placed on exploring the effect of variation of piezoelectric fiber orientation angle in the constraining layer on the control authority of the ACLD patches.

Smart control of nonlinear vibrations of laminated plates using active fiber composites

Abstract: This paper deals with the geometrically nonlinear dynamic analysis of smart laminated composite plates integrated with the patches of active constrained layer damping (ACLD) treatment. The constraining layer of the ACLD treatment is made of active fiber composite (AFC) materials. The Von Karman type nonlinear strain–displacement relations and the first-order shear deformation theory (FSDT) are adopted in deriving the coupled electromechanical nonlinear finite element (FE) model. The Golla–Hughes–McTavish (GHM) method is implemented to model the constrained viscoelastic layer of the ACLD treatment in time domain. Symmetric/antisymmetric cross-ply and antisymmetric angle-ply laminated substrate plates are considered in the numerical analyses. The results indicate that the ACLD patches significantly improve the damping characteristics of the plates for suppressing the geometrically nonlinear transient vibrations of the plates. The effects of variation of piezoelectric fiber orientation in the AFC constraining layer on the control authority of the ACLD patches have also been investigated.

Vibration mitigation for wind-induced jitter for the Giant Magellan Telescope

Abstract: The Giant Magellan Telescope (GMT) is a planned large terrestrial telescope with a segmented primary mirror with a 24.5 meter overall diameter. Like most terrestrial telescopes, the GMT resides within an enclosure designed to protect the telescope from the elements and to reduce the effects of wind on the optical performance of the telescope. Wind impingement on the telescope causes static deformation and vibration in the telescope structure that affects the alignment and image jitter performance of the telescope. Actively controlled primary mirror segments and a secondary mirror can correct for the static and low frequency portions of the wind effects, but typically the actuators do not have the bandwidth to address higher frequency components of the wind environment. Preliminary analyses on the GMT indicate that the image jitter associated with wind effects meets budgeted allowances but without much margin. Preliminary models show that the bulk of the residual jitter arises from excitation of a small number of modes in the 9 to 12 Hz range. Therefore, as a risk mitigation effort to increase the margin on the wind induced jitter, passive and active vibration mitigation approaches have been examined for the GMT, which will be the focus of this paper. Using a finite element model of the GMT along with wind loading load cases, several passive and active vibration mitigation approaches were analyzed. These approaches include passive approaches such as tuned mass dampers targeting the worst offending modes, and constrained layer damping targeting all of the modes within the troublesome frequency range. Active approaches evaluated include two active damping approaches, one using several reaction mass actuators and the other using active strut type actuators. The results of the study show that although all approaches are successful in reducing the jitter, the active damping approach using reaction mass actuators offers the lightest weight, least implementation impact, and most adaptability of any of the approaches.

Active Damping of Nonlinear Vibrations of Functionally Graded Laminated Composite Plates using Vertically/Obliquely Reinforced 1-3 Piezoelectric Composite

Abstract: This paper deals with a study on the active constrained layer damping (ACLD) of geometrically nonlinear vibrations of functionally graded (FG) laminated composite plates. The constraining layer of the ACLD treatment is considered to be made of the vertically/obliquely reinforced 1-3 piezoelectric composites (PZCs). The substrate FG laminated composite plate is composed of generally orthotropic FG layers. The generally orthotropic FG layer is a fiber reinforced composite layer in which the fibers are longitudinally aligned in the plane parallel to the top and bottom surfaces of the layer and their orientation angle is assumed to vary in the thickness direction according to a simple power-law in order to make it as a graded layer only in the thickness direction. The constrained viscoelastic layer of the ACLD treatment is modeled by implementing the Golla-Hughes-McTavish (GHM) method. Based on the first order shear deformation theory, the finite element (FE) model is developed to model the open-loop and closed-loop nonlinear dynamics of the overall FG laminated composite plates integrated with a patch of such ACLD treatment. The analysis suggests the potential use of the ACLD treatment with its constraining layer made of the vertically/obliquely reinforced 1-3 PZC material for active control of geometrically nonlinear vibrations of FG laminated composite plates. The effect of piezoelectric fiber orientation in the active 1-3 PZC constraining layer on the damping characteristics of the overall FG laminated composite plates is also investigated.

Development of a new finite element and parametric study for plates with compressible constrained layer damping

Abstract: Constrained layer damping (CLD) is widely used in many structures for vibration reduction. It is necessary to model CLD structures precisely. Most existing research studies have modeled the structures as beams, which in many cases is not a sufficient approach. These existing models are based on the assumption that shear deformation in the core layer is the only source of damping in the structure. However, previous research has shown that other types of deformation in the core layer, such as deformations from longitudinal extension and transverse compression, can also be important. To more accurately model CLD, a new plate finite element is developed in this study by assuming that there is shear as well as longitudinal and transverse deformations in the damping layer. This model can be used to better predict the structure’s dynamic characteristics, such as resonant frequencies and modal loss factors. By comparing the new model to experimental results from the open literature, this newly developed plate fin...

An experimental comparative study on non-conventional surface and interface damping techniques for automotive panel structures

Abstract: In order to increase the comfort of vehicle drivers, automotive panel structures are normally damped on their surfaces. Common surface damping treatments like free layer damping or constrained layer damping have the drawback of heavy weight and temperature as well as frequency dependent damping performance. New alternatives with simple structure, high robustness and light weight are sought. In this contribution, three different passive and active damping approaches were investigated: interface damping (ID), active constrained layer damping (ACLD) and particle damping (PD). They were surveyed under same boundary conditions and their performances were compared in terms of weight. The results show that ID strongly decouples the vibration from the source to the panel and provides steady performance over the whole frequency range. ACLD is a lightweight treatment with high damping capability for special mode shapes. PD is an effective simple damper providing excellent damping performance.

Performance Analysis of Finite Element and Energy Based Analytical Methods for Modeling of PCLD Treated Beams

Abstract: For active/passive vibration control applications, low order models of flexible structures are always preferable. Mathematical models of passive constrained layer damping (PCLD)/active constrained layer damping (ACLD) treatment generated by energy based analytical methods are of much smaller orders as compared to finite element methods (FEM). Using these analytical methods, one can get rid of complex model reduction techniques, since these model reduction techniques are subjected to errors if applied directly to PCLD or ACLD systems. However, analytical techniques cannot be applied blindly to any PCLD system. There is significant error in loss factor prediction for certain boundary conditions. This error is also dependent on the relative thicknesses of Viscoelastic material layer, constraining layer and base beam. For certain combination of the above thicknesses and under certain boundary conditions, the models generated are useless for controller design purposes. On the other hand, FEM are highly robust and can be applied easily to any set of boundary conditions with guaranteed accuracy. Also, results predicted by this method are of high accuracy for any combinations of thicknesses of different layers. The only disadvantage of this technique is the high order of the developed model. Detailed performance comparison of both the techniques to predict the modal parameters of the PCLD treated beam is presented.

A Mechanics Model and Active Control for Smart Constrained Layer Damping Structure

Abstract: The active vibration control of beam is researched by using piezoelectric constrained damping structure. The energy characteristic of each layer for the piezoelectric smart constrained damping beam is completely expressed based on the finite element method and the damping layer shearing movement relationship is described by ADF model. Then the structure mechanics model for dynamic parameters is established. Applying displacement error signal, an adaptive filter controller is designed. Under the different outside disturbance, structure vibration responses with active control are analyzed. It shows that the piezoelectric smart constrained damping structure can have good control performance for the active and it has a good engineering prospects.

Modeling and analysis of rotating plates by using self-sensing active constrained layer damping

Abstract: This paper proposes a new finite element model for active constrained layer damped (CLD) rotating plate with self-sensing technique. Constrained layer damping can effectively reduce the vibration in rotating structures. Unfortunately, most existing research models the rotating structures as beams that are not the case many times. It is meaningful to model the rotating part as plates because of improvements on both the accuracy and the versatility. At the same time, existing research shows that the active constrained layer damping provides a more effective vibration control approach than the passive constrained layer damping. Thus, in this work, a single layer finite element is adopted to model a three-layer active constrained layer damped rotating plate. Unlike previous ones, this finite element model treats all three layers as having the both shear and extension strains, so all types of damping are taken into account. Also, the constraining layer is made of piezoelectric material to work as both the self-sensing sensor and actuator. Then, a proportional control strategy is implemented to effectively control the displacement of the tip end of the rotating plate. Additionally, a parametric study is conducted to explore the impact of some design parameters on structure’s modal characteristics.

Optimal vibration control of a rotating plate with self-sensing active constrained layer damping

Abstract: This paper proposes a finite element model for optimally controlled constrained layer damped (CLD) rotating plate with self-sensing technique and frequency-dependent material property in both the time and frequency domain. Constrained layer damping with viscoelastic material can effectively reduce the vibration in rotating structures. However, most existing research models use complex modulus approach to model viscoelastic material, and an additional iterative approach which is only available in frequency domain has to be used to include the material's frequency dependency. It is meaningful to model the viscoelastic damping layer in rotating part by using the anelastic displacement fields (ADF) in order to include the frequency dependency in both the time and frequency domain. Also, unlike previous ones, this finite element model treats all three layers as having the both shear and extension strains, so all types of damping are taken into account. Thus, in this work, a single layer finite element is adopted to model a three-layer active constrained layer damped rotating plate in which the constraining layer is made of piezoelectric material to work as both the self-sensing sensor and actuator under an linear quadratic regulation (LQR) controller. After being compared with verified data, this newly proposed finite element model is validated and could be used for future research.

Numerical Modeling and Control of Rotating Plate with Coupled Self-Sensing and Frequency-Dependent Active Constrained Layer Damping

Abstract: This work proposes a coupled finite element model for actively controlled constrained layer damped (CLD) rotating plate with self-sensing technique and frequency-dependent material property in both the time and frequency domain analyses. Constrained layer damping with viscoelastic material can effectively reduce the vibration in rotating structures. However, most existing research models use complex modulus approach to model the viscoelastic material, but it limits to frequency domain analysis and the frequency dependency of the viscoelastic material is not well-included as well. It is meaningful use of the anelastic displacement fields (ADFs) that is done in order to include the frequency dependency of the material for both the time and frequency domains. Also, unlike previous ones, all types of damping are taken into account by this finite element model. Thus, in this work, a single layer finite element is adopted to model a three-layer active constrained layer damped rotating plate in which the constraining layer is made of piezoelectric material to work as both the self-sensing sensor and actuator. This newly proposed finite element model is validated, and then, as shown in numerical studies, this proposed approach can achieve effective vibration reduction in both the frequency and time domains.

Damping Characteristics of a Cantilever Plate Using Permanent Magnetic Constrained Layer Damping Strip Treatment

Abstract: Significant improvement of damping characteristics can be achieved by using the new class of magnetic constrained layer damping treatment (MCLD). This paper presents the damping properties of the first and second torsional mode for a five-layer cantilever rectangular plate treated with partial MCLD. The Rayleigh-Ritz method and Hamilton’s principle are employed in the analysis. We have chosen both single and segmented patches with different sizes. It can be observed that for the two modes single-patched MCLD treatment induces less improvement of damping characteristics especially for the short patch. The effects of calculation of parameters like placement strategies of discrete patches, the length of patches are analyzed and discussed. The results obtained from analytical show that the optimum location of the patch, for the torsional mode, is at edge of the plate. Favorable comparisons with the conventional passive constrained layer damping treatment (PCLD) on various special cases of the problem are obtained. The results demonstrate MCLD treatment still improvements over PCLD in damping structural vibrations.