Damping Behavior Research Articles

Analytical development and experimental investigation of the casting multi-plate damper (CMPD)

In parallel to efforts of enhancing the seismic performance of structures, this paper emphasizes the potential of applying casting technology into steel dampers in frame structures for seismic energy dissipation. Casting multi-plate damper (CMPD), which composed of a set of energy-dissipating plates, is proposed in this study. Based on the mechanical concept, the behavior of the damper could be adjusted for specific structures by changing the number and dimension of the energy-dissipating plates. Thus, two types of dampers (S1 and S2) with different configurations of energy-dissipating plates were designed and fabricated for comparison. A mechanical model is presented first to get a better understanding of the damper behavior. Then the experimental investigation follows, and it starts with the tensile test on bar samples. All these tensile bar samples were taken from critical locations of the damper so that the full picture of the material property could be obtained. In subsequent hysteretic tests, dampers display reasonably good seismic performance with sufficient deformation and energy dissipation capacity. In the final, the proposed mechanical model is validated by comparing with test results and the corresponding finite element (FE) models.

Equivalent circuit model of eddy current damping regarding frequency-dependence with test validation

This study proposes an equivalent circuit model to simulate the mechanical behavior and frequency-dependent characteristic of eddy current (EC) damping, with the validations from multi-physics finite element (FE) modeling and dynamic testing. The equivalent circuit model is first presented with a theoretical expression of the EC damping force. Then, the transient analysis with an ANSYS-based FE model of an EC damper is performed. The time-history forces from the FE model are compared with that from the proposed equivalent circuit model. The favorable agreement indicates that the proposed model can simulate the nonlinear behavior of EC damping under different excitation scenarios. A noncontact and friction-free planar EC damper is designed, and its dynamic behavior is measured by employing shake table testing. The experimental observations can be reproduced by the proposed equivalent circuit model with reasonable accuracy and reliability. The proposed equivalent circuit model is compared with the classical viscous model and the higher-order fractional model using a complex EC damper simulated in ANSYS to show the advantages of the proposed model regarding model simplicity and prediction accuracy. A single-degree-of-freedom (SDOF) structure with different EC damping models is further analyzed to illustrate the need for accurate EC damping modeling.

Velocity auto correlation function of a confined Brownian particle

Motivated by the simple models of molecular motor obeying a linear force-velocity relation, we have studied the stochastic dynamics of a Brownian particle in the presence of a linear velocity dependent force, $$f_s(1-\frac{v}{v_0})$$ where $$f_{s}$$ is a constant. The position and velocity auto correlation functions in different situations of the dynamics are calculated exactly. We observed that the velocity auto correlation function shows an exponentially decaying behaviour with time and saturates to a constant value in the time asymptotic limit, for a fixed $$f_s$$ . It attains saturation faster with increase in the $$f_{s}$$ value. When the particle is confined in a harmonic well, the spectral density exhibits a symmetric behaviour and the corresponding velocity auto correlation function shows a damped oscillatory behaviour before decaying to zero in the long time limit. With viscous coefficient, a non-systematic variation of the velocity auto correlation function is observed. Further, in the presence of a sinusoidal driving force, the correlation in velocities increases with increase in the amplitude of driving in the transient regime. For the particle confined in a harmonic well, the correlation corresponding to the shift relative to the average position is basically the thermal contribution to the total position correlation. Moreover, in the athermal regime, the total correlation is entirely due to the velocity dependent force.

Experimental Study on Steel Slit and Shear Panel for Seismic Resistance

AbstractThis paper summarizes the experimental campaign carried out for the development of new steel energy dissipative devices named Slit Dampers (SDs) designed for earthquake protection of structures. A total of eighty‐two steel shear plates with different openings and thicknesses are tested to investigate their behaviour under cyclic pseudo‐static loading. Eight types of steel shear plates are studied, including the SD with narrow slits that divide the plate into rectangular links, and the butterfly fuse with a diamond‐shaped opening that creates butterfly shape links in the plate. Other varying test parameters are loading rate, material strength, and the number of in‐parallel damper elements. It is expected that the proposed model can be successfully used to predict the behaviour of dampers in real‐world applications.

Viscoelastic damped response of laminated composite shells subjected to various dynamic loads

In this study, viscoelastic damped dynamic behaviors of laminated composite shells (LCS) under different dynamic loads were investigated. In order to obtain better numerical stability, the truncated series method was used in the formation of equations governing the system. While deriving the equations governing the system, the z/R terms are usually neglected, whereas only 3 and higher order terms are truncated here. The method of truncated equations has been used for the first time as suggested here to obtain viscoelastic damped behavior of dynamically loaded LCS. The governing equation of composite shells was obtained with the help of Hamilton’s principle. Afterwards, time dependent partial differential equations were obtained by applying Navier solution method to these valid equations. These equations were transformed into Laplace space in order to solve time dependent partial differential equations. The transformation of the resulting calculations from Laplace domain into the time domain was conducted with the help of Modified Durbin algorithm. In addition, one of the goals of this research is to highlight the importance of including the (1+z/R) part in the equations to account for the curvature effect of the shells. The addition of these effects and truncated series method to the equations and the investigation of their effects are the originalities of the present study. The present work obtained values were compared with the results obtained with Newmark’s approach and ANSYS finite element methods. The numerical results showed that the proposed approach is a highly effective and efficient solution that can be easily applied to laminated viscoelastic shell problems.

Hygrothermoelastic damping of beam resonators with non-Fourier and non-Fick effects

In heat and moisture environments, the coupling effects of temperature and moisture on the vibration of structures play a significant role. In this paper, a coupled hygrothermoelastic model with non-Fourier and non-Fick effects is established by introducing relaxation times or phase lags of heat flux and moisture flux. The hygrothermoelastic damping behaviors and hygrothermal distributions of an Euler–Bernoulli beam with rectangular cross-section are analyzed and an explicit formula is derived by mode analysis. The distribution of hygrothermal fields are also obtained in time domain. Numerical results are analyzed for various aspect ratios and different end supports. The effects of relaxation times of both heat and moisture flux on the damping and frequency shift of slender hygrothermoelastic beams are illustrated graphically. The obtained numerical results imply that the presence of moisture enlarges the damping of the beams and leads to more energy dissipation. Compared with the non-Fourier effect, the non-Fick effect or the relaxation time of moisture flux nearly does not affect the damping and frequency shift.

Inspection of U-shaped steel dampers based on residual plastic deformation

Hysteretic dampers are widely applied as earthquake-induced energy dissipation devices in the design practice of seismic isolated structures. Therefore, an indispensable condition of urban function recovery determines whether the dampers can be used immediately after an earthquake. The deformation behavior of U-shaped steel dampers under uniaxial (in-plane) loading was the focus of investigation in this study. In this regard, two sets of loading tests on full-scale specimens were conducted: (i) cyclic loading tests with constant deformation amplitude, and (ii) cyclic loading tests with complicated loading histories. Image analysis was used to reproduce the deformation behavior of the dampers in loading tests. According to the obtained results in the tests with constant deformation amplitude, a numerical model that can describe the relation between residual plastic deformation and cumulative damage was adopted. Important findings were provided by the experimental results of the cyclic loading tests with complicated loading histories. Additionally, an evaluation method for the residual plastic deformation–cumulative damage of U-shaped steel dampers that are loaded with in-plan excitations was proposed.

Damped harmonic vibrations of axisymmetric graphene‐enhanced cylinders in thermal environment

AbstractIn this paper, the structural damping behavior of axisymmetric nanocomposite cylinders enhanced with randomly oriented graphene nanosheets has been explored by a mesh‐free solution. The static responses of such nanocomposite cylinders under internal pressure and exposed to thermal environment are assumed as the initial condition of harmonic vibrations. Using the shape functions of moving least squares (MLS), an axisymmetric mesh‐free solution has been developed to approximate the displacement field of the graphene‐enhanced nanocomposite (GEN) cylinders. Along the thickness of these cylinders, different nonlinear functionally graded (FG) patterns are considered for the distribution of graphene nanosheets. The mechanical properties of graphene and polymer are considered to vary with temperature, and the overall properties of nanocomposite are calculated using a modified Halpin‐Tsai (HS) technique. The effects of thermal environment, graphene content, graphene dispersion, and cylinder dimension on the structural damped harmonic vibrations of axisymmetric GEN cylinders have been examined. The results indicate that the use of graphene nanosheets and their distribution significantly affect the damped harmonic vibrations of axisymmetric polymeric cylinders such that the increase of graphene content results in damped vibrations with higher frequency and shorter stationary time. In addition, thermal environment reduced the frequency of vibrations, but it has an insignificant impact on the stationary time of vibrations.

Feasibility Assessment of Stiff Seismic Base Absorbers

In this paper, a radically new concept of a Stiff Seismic Base Absorber (SBA) is proposed for seismic protection of multistory building structures. An inerter is first implemented, connecting directly the structure to the ground. This results in the decrease of the natural frequency of the structure, without decreasing its structural stiffness. Parallel, a negative stiffness-based absorber is used to increase the apparent damping behavior of the inerter. The additional mass of the SBA is connected to the structure with a negative stiffness (NS) element and to the base with a positive one. Also, an artificial damper is placed in parallel with each stiffness element. The design of the SBA includes the following novel features: (1) the SBA foresees variation in all stiffness elements, (2) the optimal system parameters are selected based on engineering criteria with proper constraints and limitations to the system dynamic responses, (3) the earthquake input motion is selected according to the seismic design codes, (4) a displacement-dependent non-linear configuration is proposed for the realization of the NS element, and (5) the detuning phenomena are observed via sensitivity analysis. Compared to other vibration absorbers, the SBA presents several advantages. An improved superstructure dynamic behavior is observed combined with small base displacements, in the order of a few centimeters. The drastically reduced base displacements render the implementation of the SBA feasible using conventional structural elements. As a result, the SBA is a realistic retrofitting option for seismic protection.

Vibration Damping Behavior of Composite Laminates Interleaved with PZT- and SMA-Particle-Dispersed Resin Mixture Films

In this study, functional particles such as piezoelectric (PZT) ceramic and shape memory alloy (SMA) particles have been incorporated in composite laminates to accelerate the loss of vibration energy. PZT ceramic particles and SMA particles are mixed with epoxy resin and rolled into a film shape before they are interleaved between prepreg plies for better distribution of the particles. Loss factor (tan δ) was measured with various particle loadings to verify the effectiveness of interleaving in the vibration damping of laminate specimens. It was observed that there existed an optimal content for maximizing the damping ability avoiding an aggregation of the particles. In addition, when PZT and SMA particles are applied simultaneously, PZT could enhance the vibration damping capability of SMA because PZT particles could generate thermal energy, and it would accelerate the phase change of the SMA particles. In this research, the effective way for enhancing the particle dispersion was suggested, and the particle loading could be controlled by finding an optimal content. Flexural moduli of the specimens were also measured, and they exhibited no change as the content of the particles increases. Therefore, dispersed particles used in this study increased the vibration damping capacity without reducing the mechanical properties.

Effect of Waste Ground Rubber Tire Powder on Vibrational Damping Behavior and Static Mechanical Properties of Polypropylene Composite Plates: An Experimental Investigation

Effect of Waste Ground Rubber Tire Powder on Vibrational Damping Behavior and Static Mechanical Properties of Polypropylene Composite Plates: An Experimental Investigation

A generalized compliance model for study of acoustic damping behavior of mixed porosity segmented perforated liner

Acoustic liners play a vital role in the reduction of aero-engine noise and combustion instabilities. In the present work, acoustic damping behavior of perforated cylindrical liners of mixed porosities is investigated both analytically and experimentally. The aim of the paper is to propose a generalized analytical model for the compliance of mixed porosity liners. The analytical results are obtained by considering the compliance of each segment of distinct porosities. Experimental results are compared with the analytical predictions to validate the proposed generalized compliance expression. Predicted results are in reasonable good agreement with the experimental results. A parametric study is carried out for different flow with variably segmented liner configurations. The effect of number of liner segments is studied. Liners with higher number of segments are shown to perform better than the liners having lesser number of segments.

Microstructure and Damping Behavior of Continuous W-Core-SiC Fiber-Reinforced Aluminum Matrix Composites

Microstructure and Damping Behavior of Continuous W-Core-SiC Fiber-Reinforced Aluminum Matrix Composites

Finite Element Modelling and Simulation of the Hysteretic Behaviour of Single- and Bi-metal Cantilever Beams using a Modified Non-linear Beta-damping Model

This paper explores a novel non-linear hysteresis model obtained from the modification of the conventional Kelvin-Voigt model, to produce a non-viscous hysteretic behaviour that is closer to metal damping. Two case studies are carried out for a vibrating cantilever beam under tip loading (bending), the first considering a single uniform material and the second considering a bimetallic structure. The damping behaviour is studied in the frequency domain (constant damping ratio model vs. Kelvin-Voigt/ beta damping model) and time-domain (proposed modified hysteresis model vs. Kelvin-Voigt/ beta damping model). In the frequency domain, it was found that the Kelvin-Voigt model essentially damps out the displacement response of the modes more than the constant damping ratio model does. In the transient analysis, the Kelvin-Voigt model likewise produced unnaturally rapid damping of the oscillations for both the single- and bi-metal beam, compared to the modified hysteretic damping model, which produced a damping behaviour closer to actual metal behaviour. This was consistent with results obtained in the frequency domain.

On the uniqueness of advancing contact angle – Water drop on smooth wood

An advancing contact angle (CA) can be measured by numerous different techniques that monitor different time intervals of a dynamic wetting process. This does raise the question: would the same value of advancing CA be obtained at different time intervals of the wetting process? This study monitored the relaxations of CA and wetting diameter of a water drop on a Diospyros crassiflora substrate (Rq = 0.41 μm) from 0.001 to 0.3 s and from 0.1 to 70 s by utilizing the same sessile drop contact angle analyzer with two different acquisition rates of 6770 and 30 fps, respectively. Subsequent analysis of the data showed that when the relaxations of the CA and wetting diameter were monitored from the moment a water drop came in contact with wood the substrate, two regions having a near-constant CA with a near quasi-equilibrium advance of the triple line were observed, and both these regions matched well with the definition of an advancing CA. For a water drop, the average CA at these two regions were found to be significantly different; ∼66° and ∼50°. The damped oscillatory behavior exhibited by the water drop during these two regions was discussed in detail as well.

Analysis of Damping and Wear Characteristics of Tungsten Carbide reinforced AA6061 Composites

In this research, vibration damping property and dry sliding wear resistance of tungsten carbide reinforced aluminium AA6061 composites were investigated. The fabrications of test specimen were carried out using stir casting method. Three samples were taken for study with percentage of reinforcements as 0%, 4% and 8% of tungsten carbide by volume fraction. The samples are cut and machined to cylindrical pin as per ASTM standard for pin-on-disc wear analysis. Another set of samples with rectangular cross section is used as beam for experimental modal analysis using Impact hammer test to study the damping factor and natural frequency. Based on the test results, it was found that there is minimum wear resistance in reinforced alloy when compared to unreinforced alloy and also reinforced alloy had improved coefficient of friction. From the impact hammer test, the result shows that reinforced alloy had high natural frequency and improved damping factor when compared with unreinforced alloy. The hard ceramic tungsten carbide particulate improves the resistance to wear as well as improved the damping behaviour. This research can be helpful in many industrial application, heavy machineries, automotive applications This material can be developed to use as machine base, chassis where wear resistance and vibration damping needs to predominantly monitored.

Can a Semi-Active Energy Harvesting Shock Absorber Mimic a Given Vehicle Passive Suspension?

Energy harvesting shock absorbers (EHSA) have made great progress in recent years, although there are still no commercial solutions for this technology. This paper addresses the question of whether, and under what conditions, an EHSA can completely replace a conventional one. In this way, any conventional suspension could be replicated at will, while recovering part of the wasted energy. This paper focuses on mimicking the original passive damper behavior by continuously varying the electrical parameters of the regenerative damper. For this study, a typical ball-screw EHSA is chosen, and its equivalent suspension parameters are tried to be matched to the initial damper. The methodology proposes several electrical control circuits that optimize the dynamic behavior of the regenerative damper from the continuous variation of a load resistance. The results show that, given a target damper curve, the regenerative damper can adequately replicate it when there is a minimum velocity in the damper. However, when the damper velocity is close to zero, the only way to compensate for inertia is through the introduction of external energy to the system.

Damping prediction of particle dampers for structures under forced vibration using effective fields

Particle damping is a promising damping technique for a variety of technical applications. However, their non-linear behavior and multitude of influence parameters, hinder currently its wide practical use. So far, most researchers focus either on determining the energy dissipation inside the damper or on the overall damping behavior when coupled to a structure. Indeed, currently almost no knowledge exchange between both approaches occurs. Here, a bridge is build to combine both techniques for systems under forced vibrations by coupling the energy dissipation field and effective particle mass field of a particle damper with a reduced model of a vibrating structure. Thus, the overall damping of the structure is estimated very quickly. This combination of both techniques is essential for an overall efficient dimensioning process and also provides a deeper understanding of the dynamical processes. The accuracy of the proposed coupling method is demonstrated via a simple application example. Hereby, the energy dissipation and effective mass of the particle damper are analyzed for a large excitation range first using a shaker setup. The particle damper exhibits multiple areas of different efficiency. The underlying structure is modeled using FEM and modal reduction techniques. By coupling both parts it is shown that multiple eigenmodes of the structure are highly damped using the particle damper. The damping prediction using the developed coupling procedure is validated via experiments of the overall structure with particle damper.

Controllability of higher order stochastic fractional control delay systems involving damping behavior

This article focuses on the problem of controllability of both cases linear and nonlinear higher order stochastic fractional control delay systems with damping behavior, which involving Caputo fractional derivative (CFD). The proposed approach utilizes the ideas of controllability Grammian matrix involving Mittag-Leffler function (MLF) and Burkholder-Davis-Gundy’s inequality. By employing Banach fixed point theorem, we establish the exact method to design a stochastic perturbation to control the considered nonlinear higher order fractional differential systems. As a final point, the derived design is illustrated with two numerical examples.

Damping characterization and its underlying mechanisms in CNTs/AZ91D composite processed by cyclic extrusion and compression

The proper combination of strength and damping performance has been a major challenge for the wide use of Mg alloys/composites in many fields. In this regard, this research focused on the effect of the CEC process and the CNTs addition on the damping behavior of AZ91D alloy. The damping capacity of CEC-processed CNTs/AZ91D composite is significantly improved compared with the initial solid-solution state. Also, although 0.5 wt% addition of CNTs to AZ91D decreases the room-temperature damping of the base alloy, its performance can be improved by the addition of 2.0 wt% CNTs. Besides, the addition of CNTs, regardless of its amount regularly increases the high-temperature damping behavior compared to the base alloy. For the solid-solution alloy/composite, when the test temperature is lower than the critical temperature, the damping is mainly advanced by the movement of dislocations between a large number of weak pinning points and a low amount of strong pinning points. Contrarily, the damping mechanism of the same material at higher than critical temperatures is mainly progressed by grain boundary sliding.