Smart Dampers Research Articles

Application of Smart Dampers for Prevention of Seismic Pounding in Isolated Structures Subjected to Near-fault Earthquakes

ABSTRACT This paper investigates the performance of the Magnetorheological damper as a smart dissipating device in the isolated buildings for prevention of seismic pounding. To that end, an isolated building was modeled by considering the pounding effect with different gap distances. Multi-objective optimization was performed to optimize the fuzzy logic control of damper for each gap distance. The results showed that the optimized semi-active control system can prevent the pounding of the building and greatly improve the structure’s behavior as compared to the isolated pounded building and even to the case without the pounding at some considered gap distances.

Smart dampers-based vibration control – Part 2: Fractional-order sliding control for vehicle suspension system

Semi-active suspension systems of vehicles using smart dampers (SmDs) such as magnetorheological dampers (MRDs) are actively developing as an attractive methodology to improve both ride comfort and road holding of many different vehicles including sedans. Because of the complex dynamic response of the SmDs and the whole system, an exact estimation of the time-varying control signal is difficult. Especially, the reality has shown that i) the error of the inverse SmDs (I-SmDs) due to noise in the measurement database used to build them may fade the control efficiency, and ii) for many high nonlinear systems, fractional-order derivative (FD)-based mathematical description could reflect their characteristics, attributes, and dynamic behaviors better than that using the integer-order-derivative-based traditional way. From the above aspects, we present an FD-based new control system for the half-car semi-active suspension system with MRDs. The proposed control system named FD-SMC consists of I-SmDs which are relied on measured data processed by the new filter CoFilter presented in Part 1 and FD-based sliding mode control (SMC) technique. The FD-SMC determines the control force, and subsequently, I-SmDs estimates current intensity applied to MRDs to generate the desired control forces. Surveys including a real application using an experimental apparatus are carried out to verify the control effectiveness of the proposed method as well as the possibility of development of this orientation.

4D printed multi-stable metamaterials with mechanically tunable performance

The function of the metamaterials is determined by the configuration and spatial arrangement of the lattice microstructure. Once manufactured, the geometry and function of the metamaterials are irreversible and cannot be adapted to the environment to be variable and adjustable. This paper studies a shape-reconfigurable, functionally deployable, mechanically adjustable and reusable intelligent multi-stable metamaterial. Based on a 4D printing method that combines digital additive manufacturing technique and thermally induced shape memory polymer exhibiting significant change in modulus of elasticity, this metamaterial is created with reconfigurable, self-expandable and mechanical properties adjustable features. The macroscopic deformation and the morphology change of the lattice microstructure on the metamaterial during the compression test are analyzed using experiment and finite element method. The adjustable, selectable, and controllable for micro-lattice in the metamaterial during deformation and recovery can be achieved by microstructure gradients and composite design methods. The new micro-lattice programmable mechanical metamaterial has excellent versatility and the ability to adapt to environmental changes. This 4D printed multi-stable metamaterial has broad application prospects, such as in soft robots, smart damping interfaces, aerospace adjustable and expandable structures, and tunable function devices.

Magnetic field enhancement technique in the fluid flow gap of a single coil twin tube Magnetorheological damper using magnetic shields

Smart dampers in the automobile suspension system bring a precise balance between the ride comfort and stability through a controllable damping coefficient. Energy absorbed by a Magnetorheological (MR) damper is a dependent function of flux density in the fluid flow gap. In this paper, magnetic field enhancement technique in the form of a single cylindrical shield and sandwich cylindrical shield is incorporated in a twin tube single coil MR damper. The field strength in different configurations of MR damper having various type of shield configuration is computationally investigated. Further, the effect of shield thickness on field strength is investigated. A significant overall improvement in the magnetic field strength is observed in the MR damper configuration having copper alloy shield.

Development of a Multiple Coil Magneto-Rheological Smart Damper to Improve the Seismic Resilience of Building Structures

Introduction:The incremental research progress on Magneto-Rheological (MR) damper and its response motivated many researchers and engineers to focus on this topic in the last decade.Methods:MR damper is classified as a semi-active vibration controlling device owing to its mechanical simplicity, low power usage, large response reduction, perfect damping mechanism, good stability, quick reaction time and robust interface.Results:In the current investigation, experimental studies were performed for the design, development, and testing of a new type of MR damper. A proposed approach was adopted for the magnetic generation using multi-coils to produce more shear force in the flow gap. The study investigates time history responses of the proposed system under an array of strong ground motions at both element and structure levels. Numerical hybrid simulation using OpenSees has also been carried out on a building structure to show the effectiveness of the new device.Conclusion:The performance of the investigated structure equipped with the proposed system indicates a large reduction in displacement and an increase in damping force under major seismic events.

Smart dampers-based vibration control – Part 1: Measurement data processing

Exploiting smart dampers (SmDs) based on data-driven models have been seen as an appropriate approach for many applications such as vehicle suspension system. Reality has shown that the error of SmDs’ identification due to noise in the measured data (MD) sets as well as uncertainty related to the mathematical tools selected to describe control systems reduces control efficiency. To overcome this issue we are interested in finding effective solutions for online filtering noise in MD, selecting and building data-driven models of SmDs, and seeking an appropriate approach to reduce the model errors. To undertake these, we divide the research into two parts; part 1 and part 2. In this current part, we focus on the filtering of the noise by proposing two new filters. Deriving from a discovered optimal data screening threshold (ODST), the first one is an ODST-based filter (ODSTbF) for dealing with random and impulse noise (IN). The second one named combined filter (CoFilter) is a combination of the ODSTbF and the median smoother to extend the filtering capability. To determine the ODST of a data source, a new algorithm for estimating the ODST named AfODST is proposed via an offline process. Many surveys using MD coming from a magnetorheological damper (MRD) are performed to evaluate positive effects of the proposed method.

A Novel Solution to Find the Dynamic Response of an Euler–Bernoulli Beam Fitted with Intraspan TMDs under Poisson Type Loading

This contribution considers a virtual experiment on the vibrational response of rail and road bridges equipped with smart devices in the form of damping elements to mitigate vibrations. The internal damping of the bridge is considered a discontinuity that contain a dashpot. Exact complex eigenvalues and eigenfunctions are derived from a characteristic equation built as the determinant of a 4 × 4 matrix; this is accomplished through the use of the theory of generalized functions to find the response variables at the positions of the damping elements. To relate this to real world applications, the response of a bridge under Poisson type white noise is evaluated; this is similar to traffic loading that would be seen in a bridge’s service life. The contribution also discusses the importance of smart damping and dampers to sustainability efforts through the reduction of required materials, and it discusses the role played by robust mathematical modelling in the design phase.

An improved micro-thermo-mechanics model for shape memory alloys: analysis and applications

In this paper, micro-mechanics of shape memory alloys (SMA) is investigated for design of smart structure and devices, based upon three dimensional constitutive model. In this work, a micro-mechanics based approach is presented. A modification in temperature field of the above model is proposed, where temperature is taken as function of time. Thermal parameters corresponding to transformation temperatures are introduced here. The model solution is presented for the of a set of initial and boundary conditions based upon any type of thermal parameters. Three particular cases for different thermal and structural loading-stresses are presented here. The solution given here expresses the response of smart dampers for various thermal and structural loading conditions. Moreover, the applications of this system were also investigated.

Nonlinear piezoelectricity and damping in partially-covered piezoelectric cantilever with self-sensing synchronized switch damping on inductor circuit

We examined a partially covered piezoelectric cantilever connected to a self-sensing synchronized switch damping on an inductor (SSDI) circuit. Nonlinear behavior, which cannot be explained by the single-degree-of-freedom model based on linear piezoelectricity, is observed in the frequency response as the excitation level increases. Here, we propose a new method that allows us to predict the attenuation performance in such a smart damping structure. We first derived the governing equation for a practical cantilever structure in which the piezoelectric elements are attached with glue and partially cover the cantilever. We include the nonlinear piezoelectricity and damping in the model. Then, we used a two-way coupled simulation technique to investigate the complex electromechanical dynamics for the piezoelectric cantilever connected to the self-sensing SSDI circuit. Our model replicates the nonlinear behavior observed experimentally. Intriguingly, the simulation revealed that, when connected to the SSDI circuit, the lower shift of the peak frequency observed in the open circuit vanished and the peak frequency shifted to higher frequency because of the increased piezoelectric coupling force. We emphasize the importance of nonlinear piezoelectricity and damping in the model and show that ignoring the peak frequency shift and the decrease in the displacement may lead to the wrong estimation in the attenuation performance, especially as the excitation level increases.

Proposed Theory of Semiactive Gains for Smart Dampers in MDOF Systems

AbstractThe use of smart dampers in civil engineering structures for vibration attenuation has proven to be promising in recent years. Nevertheless, evaluating the effectiveness of smart dampers in...

Application of smart electro-rheological dampers in semi-active control of electro-rheological sandwich plates with nanocomposite facesheets rested on orthotropic visco-Pasternak foundation

In this research, semi-active control of sandwich plates with electro-rheological (ER) core and carbon nanotubes-reinforced composite facesheets using smart ER dampers is studied. Sandwich plate is subjected to the external electric field and rested on orthotropic visco-Pasternak foundation. The material properties of ER core and nanocomposite facesheets are obtained by Yalcintas model and Eshelby–Mori–Tanaka approach, respectively. The governing equations of motion are solved by a combination between finite element and Newmark methods for clamped and simply supported boundary condition. The effects of various parameters such as applied voltage, controlled electric field and initial gap of the electrodes on the vibration suppression time are discussed. The results show that the settling time of system introduced in this work is much less than previous researches in this field which is a very important advantage.

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

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 composite plates. The three-dimensional fractional derivative constitutive relation is implemented for the viscoelastic layer. The constraining layer of the smart constrained layer damping treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composites. The von Kármán–type nonlinear strain–displacement relations are used to incorporate the geometric nonlinearity in the model. The main aim of this article is to numerically investigate the effect of carbon nanotube waviness on the nonlinear smart damping. Several thin laminated substrate fuzzy-fiber reinforced composite plates with straight carbon nanotubes and wavy carbon nanotubes with different waviness in different planes are considered with various boundary conditions and stacking sequences to numerically compute their effect on smart damping. The performance of the obliquely reinforced 1–3 piezoelectric composites is discussed and the efficacy of the present smart finite element model in terms of active control authority is also presented.

Dynamic performance of shear-thickening fluid damper under long-term cyclic loads

An experimental study on the effects of loading cycles on the performance of STF dampers (STFDs) are presented. The rheological properties of a STF sample are investigated under both ascending and descending loads. A smart damper is then developed and manufactured by employing the STF sample. Two series of cyclic tests were conducted to investigate the behaviour of the STFD under various sinusoidal loading conditions with a constant amplitude of 20 mm. Eight different loading frequencies (0.01, 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 Hz) were imposed to research on the effect of frequency. Three different loading frequencies (1, 2 and 3 Hz) were applied to the STFD under a constant amplitude (20 mm) with long-term loading (200 cycles). The energy dissipation and dynamic properties of STFD were investigated by analysing the force-displacement and force-velocity curves. The STF damping force is found to decay exponentially as the loading cycles increase. An equation is proposed for the description of STFD force at different loading cycles and frequencies.

Limitation of an adjustable two degree‐of‐freedom damper system for directional damping

AbstractFor a better and more flexible damping, a smart damper is required. Such damper should be able to adjust the damping magnitude and damping direction independently. In this work, two degree‐of‐freedom (DOF) damping with two fixed orthogonal damping directions is investigated. The damping magnitude can be adjusted independently for each damping direction. This kind of adjustment can be realized through the implementation of field responsive fluid, such as electro‐ or magnetorheological fluid. In order to describe the behavior of the damping system, investigations were conducted for several combinations of damping magnitude and velocity directions. It is shown that fully independent damping adjustment is only possible to be realized along the fixed orthogonal damping directions. Therefore, it is not possible to control the direction of the damping independently with only two damping elements. It can be concluded, that the possibility to influence the damping direction is found to be still challenging.

Vibration control in wind turbines to achieve desired system-level performance under single and multiple hazard loadings

The increased demand in energy and the need for sustainable and renewable sources of electricity in hazardous environments with significantly growing population yields the installation of more wind turbines in these areas. In addition, the technological development in material and construction methods has led to the building of taller and more flexible turbines, with inherent low structural damping. Installing modern wind turbines in offshore harsh environments or seismic prone areas can cause an increment in the probability of failure due to excessive vibrations. The current study evaluates the performance of onshore and offshore wind turbines under multihazard loads, including wind, wave, earthquake, and mass and aerodynamic imbalances for both parked and operating conditions. The Lagrangian approach is employed to model the wind turbine considering the blade/tower coupling. In order to lessen the vibrations induced by multihazard loads, external smart dampers are used and a novel energy-based probabilistic approach is employed to tune the semiactive controllers. The results show the effectiveness of employing an analytical approach for the design of semiactive controllers in vibration mitigation of a wind turbine subjected to multiple hazards.

Low-energy structures embedded with smart dampers

Building structures, subject to dynamic loadings or external disturbances, may undergo destructive vibrations and encounter different degrees of deformation. Modeling and control techniques can be applied to effectively damp out these vibrations and maintain structural health with a low energy cost. Smart structures embedded with semi-active control devices, offer a promising solution to the problem. The smart damping concept has been proven to be an effective approach for input energy shaping and suppressing unwanted vibrations in structural control for buildings embedded with magnetorheological fluid dampers (MRDs). In this paper, the dissipation energy in MRD is studied by using results from induced hysteretic effect of structural vibrations while the fluid is placed under a controlled magnetic field. Then, a frequency-shaped second-order sliding mode controller (FS2SMC) is designed along with a low-pass filter to implement the desired dynamic sliding surface, wherein the frequency responses of the hysteretic MRD is represented by its magnitude and phase describing functions. The proposed controller can thus shape the frequency characteristics of the equivalent dynamics for the MRD-embedded structure against induced vibrations, and hence, dissipate the energy flow within the smart devices to prevent structural damage. Simulation results for a 10-floor building model equipped with current-controlled MRDs, subject to horizontal seismic excitations validate the proposed technique for low-energy structures with smart devices. The closed-loop performance and comparison in terms of energy signals indicate that the proposed method allows not only to reduce induced vibrations and input energy, but also its spectrum can be adjusted to prevent natural modes of the structure under external excitations.

Dynamic performance and mechanical model analysis of a shear thickening fluid damper

This paper presents an experimental study of the dynamic performance of a self-developed shear thickening fluid (STF) damper and its mechanical model was proposed by nonlinear fitting. First, STF samples with different mass fraction and dispersion medium were fabricated by nano fumed silica and polyethylene glycol, and its rheological properties were investigated by a rheometer. Second, a smart STF damper was developed and manufactured. Its dynamic properties were experimentally investigated by establishing a vibration test bench, and results indicated that the STF damper can output variable damping force by controlling the loading frequency, loading amplitude and fluid gap. Third, the Bouc–Wen model was proposed to address the dynamic properties of STF damper, and mechanical model analysis was carried out by comparing several fitting functions. It verified that the Bouc–Wen hysteresis model can be better used to describe the nonlinear stiffness, nonlinear damping and rate-dependence characteristics of the STF damper. All these investigations can offer an effective guidance for further theoretical and application study of the smart STF damper in energy dissipation fields.

Smart damping of large amplitude vibrations of variable thickness laminated composite shells

This paper is concerned with the smart constrained layer damping (SCLD) treatment of laminated composite shells with variable thickness undergoing geometrically nonlinear vibrations. Three dimensional fractional derivative model (FDM) has been implemented for modelling the constrained viscoelastic layer of the SCLD treatment. The constraining layer of the SCLD treatment is made of vertically/obliquely reinforced 1–3 piezoelectric composites (PZCs) and acts as the distributed actuator. The strain-displacement relations are based on the simplified Novozhilov nonlinear shell theory to introduce the geometric nonlinearity in the large amplitude vibrations of the variable thickness shells. A three dimensional smart nonlinear finite element (FE) model has been developed for carrying out this analysis. Several numerical results are presented to check the accuracy of the present three-dimensional FDM for analyzing the passive and active control authority of the SCLD patch. Also the efficacy of the activated SCLD patch in controlling geometrically nonlinear vibration is computed for variable thickness shells and compared with shells of constant thickness.

Smart outrigger damper system for response reduction of tall buildings subjected to wind and seismic excitations

The outrigger damper system has recently been proposed to reduce the dynamic response of tall buildings subjected to lateral loads. Previous studies have shown that the outrigger damper system could effectively increase the response reduction capacity of tall buildings. The outrigger damper system was used not only for a response reduction of tall buildings, but also for adjusting the differential column shortening. When an outrigger damper system is designed optimally for wind or earthquake loads, it shows good control performance against each target excitation. On the other hand, the outrigger damper system designed for the wind load cannot effectively control the seismic responses and vice versa. This study examined the control performance of a smart outrigger damper system for reducing both the wind and seismic responses. The smart outrigger damper system was comprised of magnetorheological dampers. A fuzzy logic control algorithm, which was optimized by a multi-objective genetic algorithm, was used to control the smart outrigger damper system. Numerical analysis showed that the smart outrigger damper system could provide superior control performance for the reduction of both wind and earthquake responses compared to the general outrigger system and passive outrigger damper system.

Active damping of multiferroic composite plates using 1–3 piezoelectric composites

A layer-wise shear deformation theory is used to analyze the smart damping of multiferroic composite or magneto-electro-elastic (MEE) plates. The intent of this analysis is to investigate the need for incorporating additional smart elements for controlling the vibrations of multiferroic composite plates. Active constrained layer damping (ACLD) treatment has been incorporated to alleviate the vibration of MEE plate. A layer of viscoelastic material is used as constrained layer for the ACLD treatment. The coupled constitutive equations of multiferroic (ferroelectric and ferromagnetic) composite materials along with the total potential energy principle are used to derive the finite element formulation for the overall multiferroic or MEE plate. Maxwell’s electrostatic and electromagnetic relations are used to compute the electric and magnetic potential distribution. Influence of obliquely reinforced piezoelectric fibers in the piezoelectric layer of the ACLD treatment has also been investigated. In order to investigate the importance of using ACLD treatment for an active damping of multiferroic or MEE plate, an active control of MEE plate has also been analyzed by providing the control voltage directly to the piezoelectric layers of the MEE substrate plate without using the ACLD treatment. The present study suggests that for an optimal control of MEE plates, the smartness element such as the ACLD treatment is essentially required.