Viscoelastic Damping Research Articles

Experimental and analytical study of a seismic energy dissipation device made of butterfly-shaped steel plates and viscoelastic pads

This paper presents the seismic performance of a new hybrid seismic damper combining a metallic and viscoelastic damper. Two damper specimens with different configurations were tested under cyclic loading to investigate their hysteretic response to increasing loading. A curve-fitting procedure based on genetic algorithm was developed to make an analytical model for viscoelastic dampers based on the test results, and the analytical model of the hybrid damper was constructed by combining the individual models of the metallic-yielding damper and the viscoelastic damper. Both hybrid damper configurations exhibited a high energy dissipation capacity due to the complementary behavior of their components at different loading displacements. The viscoelastic component showed a relatively higher energy-dissipation capacity but a lower strength at small displacements. In comparison, the butterfly-shaped metallic yielding component exhibited a lower energy-dissipation capacity but higher strength at the same displacement. Conversely, the opposite was true at large displacements. The effectiveness of the damper was further investigated by retrofitting a four-story case study structure. Based on the test and the analysis results, it was concluded that the proposed hybrid damper has the potential to enhance the seismic performance of structures by increasing their strength and energy dissipation capacity, and that the developed analytical model turned out to simulate the nonlinear behavior of the damper adequately.

Performance enhancement of damaged RC structures with viscoelastic dampers: Damage assessment and optimal placement

Evaluating the performance degradation of the earthquake-damaged structure and optimizing the placement of dampers is important for retrofitting post-earthquake structures. In this study, a damage evolution model is developed to evaluate the degradation of strength, stiffness, and energy dissipation capacity for earthquake-damaged structures. The proposed damage model is validated using previous experimental results based on the nonlinear finite element analysis. Then, research on the optimal design of damper parameters and quantity is carried out. Considering the optimization range of earthquake-damaged structures, a genetic algorithm with multi-objective functions is developed to determine the optimal placement of viscoelastic dampers in damaged structures. The results demonstrate that the proposed damage model can effectively describe the performance degradation of damaged structures. The control effects of the acceleration response increase exhibited a maximum enhancement of 3.38 times after accounting for the optimization range of earthquake-damaged structures. The optimization results of the multi-objective function with the optimization range are better aligned with the objectives of designers.

Energy-Based Simplified Damper Design Methodology for Seismic Torsional Vibration Control of Buildings with Experimental Verification

ABSTRACT An energy-based damper design methodology is presented to achieve equal displacement at the building edges for torsionally coupled existing new buildings. Considering ductile and non-ductile RC buildings ranging from simple to complex types involving vertical irregularities, the effectiveness of the proposed methodology is studied. Shake table tests are carried out on an L-shape small-scale building model with viscoelastic dampers. The torsional response is significantly reduced by designing the dampers as per the proposed methodology. These methodologies help the designer to achieve damping constants for multistory asymmetric plan buildings using design spreadsheets with a few iterations in the damper design.

Theoretical and Non-Dimensional Investigations into Vibration Control Using Viscoelastic and Endochronic Elements

Theoretical and non-dimensional investigations have been performed to study the vibration control potential of approaches that are not only based on viscoelastic but also on endochronic elements. The latter are known from the endochronic theory of plasticity and provide the possibility of establishing rate-independent schemes for vibration control. The main question that has to be answered is: Can rate-independent damping be efficiently used to reduce mechanical vibrations? To answer this question, non-dimensional models for dynamical systems are derived and analyzed numerically in the time domain as well as in the frequency domain. The results are used to compare the performance of an optimally tuned endochronic absorber to the performance of an optimally tuned dynamic absorber with viscoelastic damping. Based on a novel closed-form representation for non-linear systems with endochronic elements, it has been possible to prove that the rate-independent control of vibration results in an overall control profit that is close to the control profit obtained by the application of well-established approaches. It has also been found that the new concept is advantageous if anti-resonances have to be considered in broadband vibration control. Based on these novel findings, a practical realization in the context of active vibration control is proposed in which the rate-independent control law is implemented with an appropriate signal processing hardware.

Uncertain sound transmission loss of composite laminated plates with embedded viscoelastic damping layer

Laminated composite structures have been widely applied in the engineering field due to their excellent capacities such as high specific stiffness, high specific strengths and tailorable anisotropic elastic properties. Embedding the viscoelastic damping layers into the laminated composites to construct co-cured composite damping structures provides an effective way to improve the sound insulation capability. In this paper, a semi-analytical model is proposed to investigate the sound transmission loss (STL) of composite laminated structure with embedded viscoelastic damping layer considering its frequency-dependent characteristic. Furthermore, Polynomial Chaos Expansion (PCE) method in conjunction with the semi-analytical model is employed for uncertainty propagation analysis of sound transmission loss of the composite laminated plates subjected to uncertain parameters of frequency-dependent interleaved viscoelastic damping layer. Moreover, numerical simulations are conducted to demonstrate the impacts of the uncertain parameters of the embedded viscoelastic damping layer on the STL of the composite laminated plate. Finally, experiments are carried out to investigate the uncertain acoustic insulation performance of composite laminated plates with embedded damping layer. Key words: Laminated composite structure; Sound transmission loss; Uncertainty analysis; Damping layer; Frequency-dependent properties

Structural vibration damping by the use of poro-elastic layers: a summary

A properly designed limp porous materials such as fibrous layers can provide damping equivalent to conventional viscoelastic dampers while providing advantages such as light weight and effective sound absorption. This then allows porous layers to be used as multi-functional noise and vibration control solutions in automotive and aerospace applications. Further, the addition of bulk elasticity to the solid phase of the porous medium is beneficial since it improves damping performance compared to equivalent limp treatments. In the work summarized here, porous media, such as fibers and foams, were designed to serve as treatments for various vibrating structures to examine their damping effectiveness. Both analytical modeling and numerical simulation based on finite element methods were involved depending on the complexity of the structure. Specifically, a Fourier transform-based computational method was introduced as the key step to allow accurate prediction of a panel's spatial response based on its wavenumber-frequency spectrum. Parametric studies have been conducted to identify the optimal bulk properties that would allow a porous layer to provide the largest possible damping within a target frequency region. Finally, design concepts for achieving the maximum damping potential of porous layers are summarized.

Eigenvalue analysis and impact response analysis for T-shaped structures with new acoustic black hole including residual thickness supported by nonlinear concentrated springs

This paper describes numerical analysis using FEM with Model Strain Energy Method for structures having a T-shaped cross section supported by nonlinear concentrated springs under impact load. An edge of the rib plate in the T-shaped structure has an Acoustic Black Hole with residual thickness. A viscoelastic damping layer is covered on the black hole. Finite element for the nonlinear springs with hysteresis are expressed and are connected to the T-shaped structures modeled by linear solid finite elements in consideration of complex modulus of elasticity. We calculated modal loss factors and transient responses using eigenmodes including coupled motions between the nonlinear springs and the T-shaped structures. From the dominant modes and the impact responses, we clarified effects of the black hole with residual thickness on the nonlinear damped responses. By adding the black hole to the structures, modal loss factors increase. Higher modal loss factors are obtained due to set the residual thickness. As the amplitude of the impact force, the responses become complicated due to the nonlinearity, and include more super harmonic and subharmonic components. These nonlinear components are reduced by adding the black hole. The less nonlinear components are given due to set the residual thickness.

Dynamic Modeling and Vibration Suppression of a Rotating Flexible Beam with Segmented Active Constrained Layer Damping Treatment

This paper uses high-order approximate coupling (HOAC) dynamics equations for the hub–beam system with segmented active constrained layer damping treatment (SACLD). To improve the damping characteristics of traditional active constrained layer damping (ACLD), the viscoelastic damping layer, and the piezoelectric constraining layer are cut at the same position. The damping characteristics of the structure are enhanced by increasing the shear strain of the viscoelastic damping layer. The finite element method is used to discretize the SACLD beam. The discontinuity of the SACLD beam element-to-element displacement achieves the notch. Based on the theory of rigid–flexible coupling dynamics, the dynamic responses of the SACLD rotating beam under different cases are studied. The results show that the segmentation method is not always effective. A SACLD beam provides better vibration suppression than an ACLD beam only when appropriate material and dimensional parameters are used. The influences of base-layer thickness, piezoelectric constraining layer thickness, viscoelastic damping-layer thickness, angular velocity, the viscoelastic damping-layer loss factor, and control gains on the vibration of the rotating flexible beam with SACLD treatment are also discussed.

Implementation and analysis of viscoelastic damping in a 2D + 1D model of railway track vibrations

One of the most important technological challenges in the railway context nowadays is reducing the noise produced by the interaction between the train wheels and the track surface, that is the rolling noise. Introducing viscoelastic damping in the railway structure is one method to mitigate this rolling noise. In the paper, we investigate the impact of damping in the vibrational response of railway tracks using different viscoelastic models and parameters available in the literature. For this purpose, the main focus here is on developing an advanced numerical model in which viscoelastic models representing the rail foundation and/or pad are implemented in the framework of the Semi-Analytical Finite Element (SAFE) method. Linear or nonlinear viscoelastic models are considered, compared and effectively implemented for accelerance computation. The obtained numerical strategy leads to affordable and accurate predictions on dynamic features of the railway structure compared to classical methods.

Two-dimensional viscoelastic beam element for ultra-large space structures based on absolute nodal coordinate formulation

Internal damping is an important factor in the dynamic behaviors of ultra-large space structures in zero damping space environment. To precisely describe the damping, this paper proposes a two-dimensional viscoelastic Euler-Bernoulli beam element based on absolute nodal coordinate formulation and Kelvin-Voigt damping model, where the damping stress is linearly dependent on the stress rate. Firstly, a precise generalized damping force model is developed using the principle of virtual work. A simplified generalized damping force model is then proposed to improve simulation efficiency by neglecting the axial damping force and a part of the transverse damping force. Numerical simulations show that the proposed damping force models will not affect the rigid-body motion of the beam. Then, a simple formula is presented to estimate the damping ratio of the beam for different parameters, which shows good agreement with the logarithmic decrement method in simulations. Finally, the effects of viscoelastic damping on the dynamic behaviors of a Sun-facing beam in space are investigated. Simulation results reveal that the viscoelastic damping can greatly reduce the vibration amplitude of the beam near the resonance frequencies.

The vibration energy dissipation behaviour of 3D-PAM type RVD

Considering that ordinary rubber materials have problems such as insufficient mechanical properties and poor shock absorption effect, a right-angle viscoelastic damper (RVD) based on 3D printed auxetic metamaterial (3D-PAM) is proposed in this paper. According to the refined finite element simulation, a dynamic energy dissipation study was conducted on the RVD. Firstly, the 3D-PAM was fabricated by selective laser sintering printing technique, and its material properties were demonstrated. Secondly, the 3D-PAM type RVD was simulated by ABAQUS to study the characteristics of dynamic energy dissipation and to investigate the stress distribution and displacement variation of the 3D-PAM layer. The results show that the hysteresis curve shape is smooth and full under all working conditions. The hysteresis loop shows linear characteristics under small displacement amplitude. As displacement amplitude increases, a hardening nonlinear response is observed. The maximum loss factor of the 3D-PAM type RVD reaches 0.64. Under the same thickness and loading conditions, the maximum loss factor has increased by 16.4% and 100.0% respectively compared to Polyurethane type RVD and Fluororubber type RVD. In conclusion, results indicate that the 3D-PAM type RVD designed in this project exhibits superior energy dissipation characteristics.

Nonlinear nonlocal damping effects under magnetic loads of a ferromagnetic-viscoelastic nanotube exposed to a nonlinear elastic medium with nonlocal viscosity

This study presents innovative results on a nonlinear dynamic model of a ferromagnetic-viscoelastic nanotube (FVN) whose dissipation effects are captured by material behavior with a linear dissipation law operating in a nonlinear geometric regime. It investigates a possible system derived from a Kelvin–Voigt type dissipation model that describes internal viscoelastic damping in the form of a parallel spring and a dashpot. In addition, a class of losses by linear viscous media in local and nonlocal damping is presented in the modeling. Magnetic load effects are studied using axial rod theory regardless of rotational inertia and shear effects. The governing equation is derived by Hamilton's principle for the FVN subjected to a transverse magnetic field resting on a nonlinear elastic foundation with viscose effects. Formulas have been developed to obtain the nonlinear damping characteristics of a single-walled nanotube. Then, multiple scale method (MSM)-based solutions and Eringen elasticity theory are applied to demonstrate the aforementioned effects on a narrow clamped-clamped (CC) nanotube in detail. The approximate analytical solution is verified by numerical integration methods and a good agreement between the approximate analytical and numerical results is observed. The effect of all important parameters such as local and nonlocal viscosity damping, nonlinear damping coefficient, linear and nonlinear stiffness of the elastic medium due to changes in amplitude vibration of the magnetic field (AVMF) and displacement responses (DR) have been investigated. The original research proposed in this paper may enable the systematic study of nonlinear damping in nanomechanical oscillators, which may help to reveal the underlying physical mechanism.

Seismic retrofit of low-rise structures using rotational viscoelastic dampers

In this research, the efficiency of a rotational viscoelastic seismic energy dissipation device is evaluated in a theoretical framework. Unlike conventional dampers which block the bays, the main advantage of this damper lies within its vertical installation scheme that provides open space in the bay and architectural flexibility. The proposed damper consists of a steel column with viscoelastic hinges at both ends that dissipate the seismic energy. Conventional viscoelastic dampers usually act under translational deformation, whereas it acts under rotational deformations in the considered scheme. The theoretical foundation is laid for the proposed damper and is verified by comparing the results with the analytical model of the damper. The developed device is proven to be versatile in terms of stiffness and energy dissipation which can be easily adjusted. The application and efficiency of this damper is validated by retrofitting a soft-first-story structure to fulfill the enhanced performance objective. The performance of the structure under a suite of earthquakes is compared before and after the seismic retrofit in terms of maximum interstory drift ratio and residual displacement.

Seismic Mitigation Effect of Lever-Type Lead Viscoelastic Node Dampers

Energy dissipation damping technology is usually used for infrastructure construction in seismic regions. In this study, a lever-type lead viscoelastic node damper (LTLVND), which can capture small rotational displacements of the infrastructure under seismic excitation, is innovatively proposed based on the leverage effect. The characteristics of energy-absorbing capacity of the LTLVND and its mitigation effect on the dynamics of the structure under seismic excitation are studied. Testing and modelling results show that a satisfactory energy dissipation effect can be observed for the innovative lead viscoelastic damper (LTLVND). Finally, a seismic analysis of a concrete frame structure with LTLVNDs is carried out. Pushover analysis and dynamic elastoplastic analysis are included. It is shown that a significant improvement in structural performance under seismic conditions can be achieved with the addition of LTLVNDs at appropriate locations.

Reliability-based topology optimization of fractionally-damped structures under nonstationary random excitation

This contribution proposes an effective reliability-based topology optimization (RBTO) framework for the layout of viscoelastic dampers of energy-dissipating structures under nonstationary seismic excitation, in which the constitutive behavior of viscoelastic damper is described by the novel fractional derivative models. To formulate the RBTO problem, the installation number of fractional viscoelastic dampers is minimized under the constraints of dynamic reliability, and the design variables are chosen as the damper parameters and the existence variables of the potential fractional viscoelastic dampers. The explicit responses are first established for the fractionally-damped structure, and the explicit response sensitivities with respect to the design variables are further derived through the adjoint variable method (AVM). On this basis, an explicit time-domain method (ETDM) is developed for explicit formulation of the statistical moments of responses and the moment sensitivities of the fractionally-damped structure, which are further employed to analytically derive the first-passage dynamic reliabilities and the reliability sensitivities of the structure based on the classical level-crossing process theory. Finally, the RBTO problem for the layout of fractional viscoelastic dampers is solved with the gradient-based method of moving asymptotes (MMA), in which the existence variables of fractional viscoelastic dampers can be driven to binary solutions by the solid isotropic material with penalization (SIMP) technique. An engineering application involving a building frame structure installed with fractional viscoelastic dampers is presented to validate the feasibility of the proposed ETDM-based RBTO framework.

Dynamic analysis of damping structures considering support stiffness

An analysis method for the random seismic response of viscoelastic damper structures with support is proposed. This method considers the influence of support stiffness and analyzes the dynamic characteristics associated with support stiffness. It also combines the advantages of the complex modal method (CMM) and the pseudo-excitation method (PEM), improving the complex integration operation in calculating the spectral moments and variances of random seismic responses. The support and the viscoelastic damper constitute the equivalent damper. The damper's constitutive relationship and structural dynamic equations are decoupled to calculate conveniently the frequency domain solution of the responses. Second, the quadratic decomposition of the power spectral density function (QD-PSDF) is applied to simplify the power spectrum and obtain the closed-form solution of spectral moments and variances. Finally, the structural dynamic characteristics and the influence of support stiffness on the vibration control effect of the equivalent damper are investigated based on the closed-form solution. The structural dynamic reliability is also discussed according to the first excursion failure criterion. The results demonstrate that the damper's control effect and structural reactions are reduced, while the dynamic reliability is also enhanced when increasing support stiffness. The performance of the structure and damper tends to stabilize when the support coefficient reaches a specific level.

Fractional-Order Zener Model with Temperature-Order Equivalence for Viscoelastic Dampers

Viscoelastic (VE) dampers show good performance in dissipating energy, being widely used for reducing vibration in engineering structures caused by earthquakes and winds. Experimental studies have shown that ambient temperature has great influence on the mechanical behavior of VE dampers. Therefore, it is important to accurately model VE dampers considering the effect of temperature. In this paper, a new fractional-order Zener (AEF-Zener) model of VE dampers is proposed. Firstly, the important influence of fractional orders on the energy dissipation ability of materials is analyzed. Secondly, an equivalent AEF-Zener model is developed that incorporates the ambient temperature and fractional-order equivalence principle. Finally, the chaotic fractional-order particle swarm optimization (CFOPSO) algorithm is used to determine the model’s parameters. The accuracy of the AEF-Zener model is verified by comparing model simulations with experimental results. This study is helpful for designing and analyzing vibration reduction techniques for civil structures with VE dampers under the influence of temperature.

Mechanical Properties of Improved Multiple-Layers Viscoelastic Damper

Viscoelastic dampers (VEDs) have been implemented successfully to reduce structural vibrations due to earthquakes and wind events. Conventional VEDs consist of two viscoelastic (VE) layers chemically bounded at their entire contact surface to three steel plates. This configuration has proven to be efficient in controlling the structure vibration. It has also been reported that VEDs can dissipate energy at any level of vibration, producing damping forces. However, when very large damping forces are required, the shear area of the VE layers and the steel plates should be increased to reach the target damping force since the energy is dissipated by hysteretic shear deformation developed in the VE material. Two main issues are associated with this large area. First, the steel plates are more susceptible to experiencing buckling due to out-of-plane deformations. Second, the overall size of the damper becomes larger which is not desirable from the architectural perspective and sometimes from the space usage perspective. As a solution, this study proposes an innovative VED so-called multiple-layers viscoelastic damper (MLVED) able to produce larger damping forces. The proposed MLVED consists of four VE layers bounded between five steel plates. The dynamic mechanical properties of MLVED are initially investigated through a full-scale test. With the test results, the finite element model is developed and calibrated using the commercial software ABAQUS. At a later stage, the calibrated model was used to investigate numerically the mechanical performance of MLVED if different VE layers areas and thicknesses are considered. Results indicated that the proposed MLVED possesses good energy dissipation capacity and its mechanical properties are strongly influenced by strain amplitude rather than loading frequency. Numerical results also showed that the damper is effective in dissipating energy even if different VE layers areas and thicknesses are considered. However, an optimal combination between the area and thickness of the VE layers needs to be found to maximize the damper performance.

Vibration response of viscoelastic nanobeams including cutouts under moving load

This manuscript presents a mathematical model and numerical solution to predict vibration responses of nonlocal strain gradient (NLS) perforated viscoelastic nanobeam under dynamic moving loads. The microstructure and size length scales are considered in the frame of NLS theory. The viscoelastic damping of the structure is considered by linear Kelvin Voigt viscoelastic model. Timoshenko and Euler Bernoulli beam theories are developed to consider both thin and thick structure response. The moving load is portrayed by point load and harmonic type. The dynamic equations of motion incorporating viscoelasticity and size dependency effects is derived by using Hamilton principle. A differential quadrature method (DQM) with Chebyshev–Gauss–Lobatto formula is used to discretize the space domain and solve the model numerically. The obtained results are validated and compared with available literature. Numerical studies are conducted to show the influence of the material viscosity parameter, perforation parameters, shear deformation effect, nonlocal strain gradient, moving load velocity, and beams slenderness ratio on the dynamic behavior of viscoelastic perforated nanobeams under moving load. The material viscosity parameter can effectively control the magnitude and stability of the magnification factor profiles. Higher filling ratios result in larger values of the dynamic magnification factor, whereas larger numbers of hole rows lead to smaller values. The proposed procedure is supportive in the analysis and design of perforated viscoelastic NEMS structures under moving load.

New general decay results for a fully dynamic piezoelectric beam system with fractional delays under memory boundary controls

In this paper, we investigate the general stability results of a fully dynamic piezoelectric beam system with internal fractional delays under memory boundary controls. Firstly, by introducing two new equations and using two Volterra's inverse operators to deal with fractional delay terms and boundary memory terms, respectively, a new equivalent system is obtained. Secondly, by combining Faedo–Galerkin approximations with the compactness argument, we prove the local existence and uniqueness of weak solution. Finally, under a broader class of kernel functions, by constructing Lyapunov functionals and new equations and applying some technical lemmas, we establish the optimal and explicit energy decay results for two cases, namely, initial values and without imposing initial values equal to 0, that is, . It is worth pointing out that we focus more on the analysis of , because the stability results of are special cases of . This is the first time to analyze the stability of strong coupling problem by combining internal fractional delay and boundary viscoelastic damping. The obtained general decay results are not necessarily exponential or polynomial, which generalize the relevant results in the existing literature.