Showing papers on "Constrained-layer damping published in 2019"

Simplification of finite element modeling for plates structures with constrained layer damping by using single-layer equivalent material properties

Abstract: As an effective approach of suppressing vibrations, the constrained layer damping (CLD) has drawn wide attention from the automotive and aerospace industries. However, most of the existing investigations focus on the beam structures with CLD and few studies have been done on the plate structures with CLD. Considering the practical applications, this work studies the finite element (FE) modeling of plate structures with CLD by considering the shear and extension strains in all of three layers. To reduce the computational cost and ensure the accuracy, a simplified single-layer equivalent method is originally proposed to model the plate structure with CLD based on the equivalent material properties. In this method, the equivalent material properties are obtained by defining a new equation which includes the equivalent bending stiffness. By nonlinear regression of these responses at resonance frequencies, the equivalent bending stiffness can be obtained, and the plate structure with CLD can be regarded as a regular single-layer plate for modeling. The simulation result shows that the proposed simplified single-layer equivalent method using single-layer equivalent material properties is efficient and accurate for modeling plate structures with CLD.

Finite element simulation of controlled frequency response of skew multiphase magneto-electro-elastic plates:

Abstract: The linear frequency response of skew multiphase magneto-electro-elastic composite plate embedded with active constrained layer damping treatment has been studied. The volume fraction of piezoelect...

Vibration Control of an Aero Pipeline System with Active Constraint Layer Damping Treatment

Abstract: In this paper, vibration control of an aero pipeline system using active constrained layer damping treatment has been investigated in terms of the vibration and stress distribution. A three-dimensional finite element model of such a pipeline with active constrained layer damping (ACLD) patches is developed. The transfer of the driving force under harmonic voltage is analyzed based on the finite element model. The vibration control of the pipeline with active constrained layer damping treatment under different voltages is computed to analyze the influence of control parameters and structural parameters on the control effect. An experiment platform is developed to validate the above relations. Results show that the performance of the active constrained layer damping treatment is affected by the elastic modulus and thickness of the viscoelastic layer, control voltage and structure size. The performance increases significantly with the rising of the control voltage and cover area of ACLD patches among these parameters.

Damping Characterization of Hybrid Carbon Fiber Elastomer Metal Laminates using Experimental and Numerical Dynamic Mechanical Analysis

Abstract: Lightweight structures which consist to a large extent of carbon fiber reinforced plastics (CFRP), often lack sufficient damping behavior. This also applies to hybrid laminates such as fiber metal laminates made of CFRP and aluminum. Since they are usually prone to vibrations due to their high stiffness and low mass, additional damping material is required to meet noise, vibration and harshness comfort demands in automotive or aviation industry. In the present study, hybrid carbon fiber elastomer metal laminates (HyCEML) are investigated which are intended to influence the damping behavior of the laminates by an elastomer interlayer between the CFRP ply and the aluminum sheets. The damping behavior is based on the principle of constrained layer damping. To characterize the damping behavior, dynamic mechanical analyses (DMA) are performed under tension on the elastomer and the CFRP, and under three point bending on the hybrid laminate. Different laminate lay-ups, with and without elastomer, and two different elastomer types are examined. The temperature and frequency dependent damping behavior is related to the bending stiffness and master curves are generated by using the time temperature superposition to analyze the damping behavior at higher frequencies. A numerical model is built up on the basis of DMA experiments on the constituents and micro mechanical studies. Subsequently, three point bending DMA experiments on hybrids are simulated and the results are compared with the experimental investigations. In addition, a parameter study on different lay-ups is done numerically. Increasing vibration damping is correlated to increasing elastomer content and decreasing elastomer modulus in the laminate. A rule of mixture is used to estimate the laminate loss factor for varying elastomer content.

A four-node quadrilateral element for vibration and damping analysis of sandwich plates with viscoelastic core:

Abstract: Constrained layer damping treatments have been widely used as an effective way for vibration control and noise reduction of thin-walled plates and shells. Despite extensive application in vibration...

Damping Analysis of Cylindrical Composite Structures with Enhanced Viscoelastic Properties

Abstract: Constrained layer damping treatments are widely used in mechanical structures to damp acoustic noise and mechanical vibrations. A viscoelastic layer is thereby applied to a structure and covered by a stiff constraining layer. When the structure vibrates in a bending mode, the viscoelastic layer is forced to deform in shear mode. Thus, the vibration energy is dissipated as low grade frictional heat. This paper documents the efficiency of passive constrained layer damping treatments for low frequency vibrations of cylindrical composite specimens made of glass fibre-reinforced plastics. Different cross section geometries with shear webs have been investigated in order to study a beneficial effect on the damping characteristics of the cylinder. The viscoelastic damping layers are placed at different locations within the composite cylinder e.g. circumferential and along the neutral plane to evaluate the location-dependent efficiency of constrained layer damping treatments. The results of the study provide a thorough understanding of constrained layer damping treatments and an improved damping design of the cylindrical composite structure. The highest damping is achieved when placing the damping layer in the neutral plane perpendicular to the bending load. The results are based on free decay tests of the composite structure.

Chatter stability of the constrained layer damping composite boring bar in cutting process

Abstract: Traditional boring bars are generally made up of isotropic metallic materials and exhibit extremely poor chatter suppression ability. For enhancing the chatter stability, using anisotropic composit...

Active control of doubly curved laminated composite shells using elliptical smart constrained layer damping treatment

Abstract: In this paper, performance of the smart constrained layer damping (SCLD) treatment with elliptical geometrical plan form is investigated for controlling the vibrations of various types of doubly curved composite shells. The SCLD treatment is composed of a viscoelastic layer and an advanced constraining piezoelectric composite (PZC) layer attached at the top surface of the composite shell. A mesh free (MF) model of the smart composite shell has been developed based on the element free Galerkin approach to study its dynamic behaviour within the framework of a mixed layerwise displacement field theory considering transverse extensibility. Spherical, paraboloid and hyperboloid type composite shells with antisymmetric/symmetric cross-ply as well as general angle-ply lamination sequences are considered for the analysis. The numerical results demonstrated that the elliptical SCLD patches are more efficient in attenuating the vibration of the spherical and paraboloid laminated shells while the regular rectangular/square plan form patches are effective for the hyperboloid shells. The numerical results also indicate that the elliptical patches are having higher performance index in enhancing the active damping characteristics of the composite shells. Investigations are also carried out to analyze the effect of the variation in orientation of the piezoelectric fibers in the active PZC layers in attenuating the vibration of shells.

Sound Radiation Analysis of Constrained Layer Damping Structures Based on Two-Level Optimization.

Abstract: Constrained layer damping (CLD) is an effective method for suppressing the vibration and sound radiation of lightweight structures. In this article, a two-level optimization approach is presented as a systematic methodology to design position layouts and thickness configurations of CLD materials for suppressing the sound power of vibrating structures. A two-level optimization model for the CLD structure is developed, considering sound radiation power as the objective function and different additional mass fractions as constraints. The proposed approach applies a modified bi-directional evolutionary structural optimization (BESO) method to obtain several optimal position layouts of CLD materials pasted on the base structure, and sound power sensitivity analysis is formulated based on sound radiation modes for the position optimization of CLD materials. Two strategies based on the distributions of average normalized elemental kinetic energy and strain energy of the base plate are proposed to divide optimal position layouts of CLD materials into several subareas, and a genetic algorithm (GA) is employed to optimally reconfigure the thicknesses of CLD materials in the subareas. Numerical examples are provided to illustrate the validity and efficiency of this approach. The sound radiation power radiated from the vibrating plate, which is treated with multiple position layouts and thickness reconfigurations of CLD materials, is emphatically discussed.

Active damping of geometrically nonlinear vibrations of smart composite plates using elliptical SCLD treatment with fractional derivative viscoelastic layer

Abstract: In this paper, the performance of elliptical smart constrained layer damping treatments on active damping of geometrical nonlinear vibrations of smart laminated composite plates are analyzed. The constraining layers of the damping treatments are comprised of vertically/obliquely reinforced 1–3 piezoelectric composites, while the constrained layers are of isotropic viscoelastic material, modelled using the three dimensional fractional order derivative model. A meshfree model of the smart composite plate is developed for analyzing its nonlinear transient responses within the framework of a layerwise shear and normal deformation theory considering the von-Karman type geometric nonlinearity. Thin composite plates integrated with elliptical/rectangular patches of the smart constrained layer damping treatments and having different stacking sequences and boundary conditions are considered for presenting the numerical results. The numerical analyses demonstrate the higher effectiveness of the elliptical patches over the rectangular ones in attenuating the nonlinear vibrations of laminated composite plates.

Effect of carbon nanotube waviness on smart damping of geometrically nonlinear vibrations of fuzzy-fiber reinforced composite plates:

Abstract: In this article, we present a finite element model for the three-dimensional analysis of smart constrained layer damping of geometrically nonlinear vibrations of laminated fuzzy-fiber reinforced co...

A reduced passive constrained layer damping finite element model based on the modified improved reduced system method

Abstract: This paper proposed a new reduced passive constrained layer damping finite element model. The passive constrained layer damping structure is a sort of sandwich plate made up of a viscoelastic core ...

Dynamic Behaviour Adaptation of Lightweight Structures by Compressible Constrained Layer Damping with Embedded Polymeric Foams and Nonwovens

Abstract: Evanescent morphing in combination with an original concept of Compressible Constrained Layer Damping (CCLD) is a novel and promising approach for dynamic behaviour adaptation. The crucial component of the CCLD is a compressible intermediate layer with its thickness and material properties controlled by fluid actuation, enabling the adjustment of the damping and stiffness of the overall system. To estimate the potential of the CCLD, an analytical model was developed which describes the vibration behaviour of the overall structure, taking into account the compression-driven properties of the intermediate layer. The results confirm the principal correctness of the initial theoretical assumptions regarding the adaptive dynamic behaviour of structures with CCLD treatment. A significant vibration mitigation as well as a high adaptability of dynamic behaviour were observed, however, they show a complex dependence on the system configuration. Nevertheless, the developed analytical modelling approach can already be used for a preliminary system design. Besides the analysed polymer-based foams as the intermediate layer, nonwovens also exhibit compression-dependent shear properties and can therefore be used in CCLD. First preliminary investigations show that the damping performance is on average about ten times better than that of the polymeric foams.

On Brake Pad Shim Characterization: a Homogenization Approach and Finite Element Analysis

Abstract: Brake squeal is a typical problem of “Noise, Vibration, Harshness” (NVH) phenomena in the automotive world leading to potential customer complaints. This high frequency noise in the audible frequency range of approximately 1 kHz to 15 kHz is induced by self excitation resulting from the frictional contact between brake pad and disk. A typical industrial countermeasure to address this problem is the mounting of thin composite structures consisting of elastomer and steel layers, so called shims, on the pad backplates. They are applied to increase the damping and to influence the vibration shapes.

Effectiveness of piezoelectric fiber reinforced composite laminate in active damping for smart structures

Abstract: This paper deals with the effect of ply orientation and control gain on tip transverse displacement of functionally graded beam layer for both active constrained layer damping (ACLD) and passive constrained layer damping (PCLD) system. The functionally graded beam is taken as host beam with a bonded viscoelastic layer in ACLD beam system. Piezoelectric fiber reinforced composite (PFRC) laminate is a constraining layer which acts as actuator through the velocity feedback control system. A finite element model has been developed to study actuation of the smart beam system. Fractional order derivative constitutive model is used for the viscoelastic constitutive equation. The control voltage required for ACLD treatment for various symmetric ply stacking sequences is highest in case of longitudinal orientation of fibers of PFRC laminate over other ply stacking sequences. Performance of symmetric and anti-symmetric ply laminates on damping characteristics has been investigated for smart beam system using time and frequency response plots. Symmetric and anti-symmetric ply laminates significantly reduce the amplitude of the vibration over the longitudinal orientation of fibers of PFRC laminate. The analysis reveals that the PFRC laminate can be used effectively for developing very light weight smart structures.

Multilayer constrained-layer damping

Abstract: Provided herein is are multilayer damping laminates comprising alternating damping and constraining layers. The materials and configurations of the damping layers are selected such that the damping layers have a decreasing glass transition temperature profile beginning at the first damping layer, allowing the laminates to effectively dissipate vibrations over a wider range of operating temperatures and/or frequencies. Also provided are systems and methods using the multilayer damping laminates.

Passive vibration control of plate using nodal patterns of mode shape

Abstract: Passive constrained layer damping (PCLD) is nowadays a general method for reducing vibrations. Constrained layer damping (CLD) is a very good technology in terms of reducing vibration energy. This paper deals with optimal damping of first three modes of a thin square cantilever plate by constrained viscoelastic layers which are positioned according to the nodal patterns of the mode. In essence, the CLD patches are cut according to the nodal patterns and then applied on to the bare plate. Thus, this approach uses prior information of the deformation patterns of the plate. The ABAQUS finite element analysis software was used to create viscoelastically damped plate models subjected to forced vibration. The direct steady-state dynamic analysis was used to obtain the frequency response functions from which the resonance frequencies of the models were derived. Vibration control using nodal pattern CLD patches is a better way to apply CLD treatment to a plate. This is because the mode shapes give good predictions of where the maximum strains are in the plate as well as the design and size of the damping patches required. It is believed that the methodology proposed in this research work is capable of providing good results.

Experiment Investigation of Constrained Layer Damping Used for Vibration Suppression of Railway Wheel

Abstract: Noise is one of the major factors restricting the development of rail transit. Wheel/rail noise, especially wheel noise is one of the most important sources of rail traffic noise. Wheel noise is usually divided into rolling noise, curve squeal noise and impact noise. The rolling noise occurs on straight rail is considered to be generated by the web coupling vibration caused by the radial excitation of the wheel. In this paper, the axial and radial coupling frequencies of wheels are extracted by modal testing, and the dominant modes in each coupling frequencies are indicated. A constrained layer damping (CLD) ring mounted on the wheel tire is proposed. The principle of the damping ring is to reduce the vibration of the coupled web by reducing the radial vibration of the wheel tread so as to reduce the noise radiation. The experiments not only including the vibration suppression characteristics of the constrained damping ring, but also compares it with the friction damping ring which is widely used nowadays. The data of modal frequency and modal damping ratio are extracted, and the transfer functions of the wheels under the conditions of the constrained layer damping ring, the friction damping ring and the non-installed damping ring are tested. The results show that the constrained layer damping ring can effectively reduce the vibration of wheels in wide frequency domain.