Passive Tuned Mass Damper Research Articles

Finite Element Model for Vibration Serviceability Evaluation of a Suspended Floor with and without Tuned Mass Dampers

This study aims to provide an accurate finite element (FE) modeling method for structural vibration serviceability evaluation of the suspended floor under human-induced excitation. The fundamental dynamic characteristics and human-induced vibration responses of a typical suspended floor were first measured via a series of field tests. Subsequently, the overall and local equivalent FE models of the suspended floor were respectively established, and their applicability was then verified by comparing the predicted dynamic characteristics and responses of the suspended floor with the corresponding field test results. Finally, passive tuned mass dampers (TMDs) were designed for vibration control of the suspended floor using the local equivalent FE model, and the applicability of the local FE model in assessing the vibration serviceability of the suspended floor with TMDs was further confirmed via pedestrian-induced vibration tests. Results demonstrate that the simplified local equivalent FE model proposed in this study can well replace the complicated overall FE model to evaluate the vibration serviceability of the suspended floor with and without TMDs.

Minimization of the Primary Structure Response Under Random Excitation Using High-Performance Passive Tuned Mass Damper Ineter Control Configurations

Minimization of the Primary Structure Response Under Random Excitation Using High-Performance Passive Tuned Mass Damper Ineter Control Configurations

A novel active tendon pendulum tuned mass damper and its application in transient vibration control

Enhancing the performance characteristics of Tuned Mass Dampers (TMDs), in particular extending their narrow frequency band of operation, has been the subject of many researches. In the adaptive type of TMDs, the device's properties can be adjusted gradually in response to a slight alteration in the excitation characteristics and physical properties of the main structure. A novel vibration absorbing system, namely Active Tendon Pendulum TMD (AT-PTMD), is proposed in the present study. The device consists of a simple pendulum whose horizontal movement is restricted by a tendon with an adjustable tensile force which is attached to the pendulum’s rod. The device is designed and formulated, and its efficiency is assessed numerically and experimentally. For this purpose, a 3-degree of freedom structure is considered. Scrutinizing the responses of the uncontrolled, passively controlled and actively controlled structure shows the appropriate performance of the AT-PTMD in comparison with the passive TMD system in transient vibration reduction, particularly in reducing the total vibrational energy of the structure's response. Considering the achieved results, the proposed AT-PTMD system is capable of reducing the maximum displacement and acceleration of the main structure up to 43% and 37%, respectively, which substantiates its excellence over the common passive vibration absorbing devices. The case study also proves that the utilized mechanism for adjusting the equivalent stiffness of AT-PTMD increases its operating frequency range by 105% compared to common TMDs. Unlike active structural control systems, the suggested approach will not induce structural instability in any operating mode.

Passive, semi-active, active and hybrid mass dampers: A literature review with associated applications on building-like structures

In this paper, a state-of-the-art literature review is presented emphasising on the development of control variants for mass damper schemes on building-like structures. Additionally, a systematic literature review is conducted addressing three relevant questions: What type of mass damper is preferable by the associated industry? How are mass dampers distributed around the world? Is industry following research? Through the systematic literature review, updated lists of mass damper implementations and control algorithm applications in real-life structures were compiled. 208 case-studies are discussed in total. It is found that, 63% of them refer to passive tuned mass dampers, 31% to hybrid mass dampers, 4.0% to active mass dampers and only 2% to semi-active mass dampers. Regarding control algorithms, controllers of 24 structures driving semi-active, active or hybrid mass dampers are presented. It is concluded that the industry considerably lags behind latest structural control research both regarding implementations and overall management.

A novel semi-active tuned mass damper with a continuously tunable stiffness

A passive tuned mass damper can only be designed to have a good damping effect near the resonance frequency of the primary structure. To overcome this limitation, a novel semi-active tuned mass damper with continuously tunable stiffness is proposed in this paper. The proposed design features a compact mechanism that can vary its stiffness by changing the number of active coils in parallel and series configurations of helical springs. The real-time control of the stiffness is achieved by designing and implementing a driving system for this mechanism. The motion characteristics and required driving torque for the designed prototype are also examined during the stiffness tuning process. It is demonstrated that the novel semi-active tuned mass damper can tune its stiffness over a wide range, and consequently tune its working frequency band to a desirable region with a proper control law. The effectiveness of the proposed prototype was investigated numerically and experimentally with respect to one-degree-of-freedom harmonic excitations in the frequency ratio range of 0.8–1.2. The results indicate that the prototype preserves optimal vibration suppression performance across a broad frequency range. Thus, the proposed semi-active tuned mass damper can provide a simple and effective in-situ tunable tool for suppressing primary structure vibration in the presence of non-stationary vibratory excitations.

Comparison of Passive and Active Tuned Mass Dampers for Structures Subjected to Earthquake Excitations

Passive and active control systems have been used in practical applications for new or existing structures. Active systems have generally better performance compared to passive ones, but the control force ad time-delay effects in the production of this control force are needed to be considered. In this study, passive tuned mass dampers (TMDs) and active tuned mass dampers (ATMDs) are compared for structures subjected to earthquake motions. For optimization of both systems, an improved harmony search algorithm is proposed. In the optimum design of ATMD, time-delay and control force limitation are considered. The comparison is presented for a 15-story reinforced concrete (RC) frame structure. According to the results, ATMD is effective than TMD in the reduction of structural displacement.

Design and Application of Double-Parallelograms-Based Tuned Mass Damper for Low-Frequency Vibration Absorption

Abstract Low-frequency vibration suppression is challenging in practical engineering problems due to the harsh requirement for vibration reduction devices, which requires constant low stiffness over a wide amplitude range. A passive tuned mass damper (TMD) composed of a positive stiffness module (PSM) in parallel with a negative stiffness module (NSM) is proposed, which are implemented by serial double-parallelograms (DP) and parallel-DP, respectively. The PSM has a large deflection range of constant stiffness for a given beam length, while the NSM offers negative stiffness within a certain deflection range when applied with axial load above the critical threshold. Based on the closed-form modeling of the stiffness modules using the beam constraint model (BCM), the design and analysis of the PSM and NSM are carried out considering the nonlinearity under large deflections. Afterward, with the structure of TMD implemented, its stiffness characteristics and low-frequency tunability are experimentally validated. Finally, the application on a suspension bridge model shows that a maximum of 29.8-dB vibration reduction of low-frequency mode is attained within the frequency range of interest. The proposed TMD well attenuates the vibrations excited by sweep sinusoidal and harmonic excitations under prespecified threshold levels of acceleration.

Adaptive-passive tuned mass damper for structural aseismic protection including soil–structure interaction

As one of the most traditional vibration mitigation devices, tuned mass dampers (TMDs) are applied widely in aseismic protection of building structures. The control effect of a passive TMD is depended on its parameters, especially the frequency ratio. Nevertheless, passive TMDs are high sensitive to the frequency detuning issue, and a mistuned TMD will lose its aseismic protection. Soil-structure interaction (SSI) will deviate the structural frequency and lead to a mistuned TMD. Besides, different soil conditions will lead to different frequency deviations of the primary structure. However, it may be difficult to obtain parameters of the soil exactly. To solve this problem, a recently developed adaptive-passive eddy current pendulum TMD (APEC-PTMD) is applied to a benchmark 40-story tall building including SSI in this study, and four different soil conditions are considered. The APEC-PTMD can identify the optimal TMD frequency in the building with different soil types, and then retune itself through adjusting the pendulum length, and also the air gap between the conduct plate and permanent magnets to reset its damping ratio. Therefore, no prior knowledge of the soil condition is needed for the APEC-PTMD. To verify the aseismic protection effect, 44 far-field earthquake excitations are chosen, and two passive TMDs are used for comparison, while one is optimized for the base-fixed structure and the other is optimized based on the dense-soil model. The passive TMD will become mistuned when SSI is considered or soil parameters are changed, while APEC-PTMD can adapt to the structural dominant frequency with different SSI. Therefore, it always works as a passive TMD with well-tuned parameters. Results show that the APEC-PTMD has a better aseismic protection than the passive TMD, especially in the soft-soil model, and it has an excellent control effect compared to the without TMD case at the same time.

Design and Simulation of a Passive Absorber to Reduce Measured Postural Tremor Signal.

Tremor is a semirhythmic oscillatory movement of a body part caused by alternating simultaneous contractions of an antagonistic muscle group. Medical and surgical treatments used to reduce the symptoms of involuntary tremor can cause negative side effects. This study examined the ability of passive vibration absorbers in reducing the amplitude of postural tremor (PT). Inertial measurement unit (IMU) was used to record PT signals at the forearm and hand of a patient. IMU signal was used to excite an upper limb modeled to represent the flexion-extension vibrational motion at the joints. Equations of motion were solved numerically to obtain a response that fits the measured tremor signal. Passive tuned mass damper (TMD) was modeled as a cantilever beam and a screw placed along its length, at a position reflecting its operational frequency. Natural frequency of the TMD was derived for different mass positions and validated numerically and experimentally. Modal damping ratio of the TMD, for each mass position, was also estimated. Mass position and damping coefficient of the TMD were optimized depending on the minimization in the power spectral density (PSD) of angular displacement amplitude at the wrist joint. Optimized three-TMD system of 28.64 g total effective mass with the estimated modal damping ratio reduced 83.1% of the PSD of the angular displacement amplitude. This study showed the performance ability of a lightweight passive absorber in controlling the involuntary tremor of a system excited by the measured tremor signal of a patient.

Design of a Semiactive TMD for Lightweight Pedestrian Structures Considering Human–Structure–Actuator Interaction

Lightweight pedestrian structures constructed with high strength-to-weight ratio materials, such as fiber-reinforced polymers (FRP), may experience large accelerations due to their lightness, thus overcoming the serviceability limit state. Additionally, uncertainties associated with human–structure interaction phenomena become relevant. Under these circumstances, variations in pedestrian actions could modify the modal properties of the coupled human–structure system and classical approaches based on passive Tuned Mass Dampers (TMD) do not offer an effective solution. An alternative solution is to use a Semiactive TMD (STMD), which includes a semiactive damper that, when properly designed, may be effective for a relatively broad frequency band, offering a robust solution when significant uncertainties are present. Thus, this paper presents a design methodology for the design of STMDs applied to lightweight pedestrian structures including human–structure and actuator–structure interaction. A multiobjective optimization procedure has been proposed to simultaneously minimize structure acceleration, inertial mass, and maximum damper force. The methodology has been applied to a lightweight FRP footbridge. Realistic simulations, including system uncertainties, interaction phenomena, nonlinear damper model, noise-contaminated signals, and the practical elements (in-line digital filters) needed for the successful implementation of the control law, validate the methodology. As a conclusion, the STMD is more effective than its passive counterpart in both, canceling the response or achieving similar performance with significant lower inertial mass.

Design Method of Tuned Mass Damper by Linear-Matrix-Inequality-Based Robust Control Theory for Seismic Excitation

AbstractThis paper presents a new design method based on a robust-control strategy in the form of a linear matrix inequality (LMI) approach for a passive tuned mass damper (TMD), which is one of the common passive-control devices for structural vibration control. To apply the robust control theory, we first present an equivalent expression that describes a passive TMD as an active TMD. Then, some LMI-based condition is derived that not only guarantees robust stability but also allows us to adjust the robust H∞ performance. In particular, this paper considers the transfer function from a seismic-wave input to structural responses. Unlike other methods, this method formulates the problem to be a convex optimization problem that ensures a global optimal solution and considers uncertainties of mass, damping, and stiffness of a structure for designing a TMD. Numerical example uses both a single-degree-of-freedom (SDOF) and 10DOF models and seismic waves. The simulation results demonstrated that the TMD that is designed by the presented method has good control performance even if the structural model includes uncertainties, which are the modeling errors.

Vibration Mitigation of Tunnel Structures via a Novel Passive Tuned Mass Damper

In this work, a novel passive tuned mass damper is introduced to mitigate the harmful vibrations in tunnel structures under moving trains/vehicles. First, a mechanism with inertial amplification effect is introduced. The transfer function of an SDOF system with the proposed inertial amplification system (SDOF-IAM) is presented. The adjustability of the proposed IAM is discussed. Second, replacing the SDOF by using the SDOF-IAM system, a novel passive tuned mass damper is proposed. Superior to the traditional TMD, the geometrical parameters of the present IAM-TMD can be changed to adjust to the vibration mitigation property of the TMD. A parametric study is also conducted to evaluate the influences of the geometrical parameters on the critical parameters of the TMD (the anti-resonant frequency, the effective mass parameter, and so on). Superior to the TMD, the vibration mitigation effect of the IAM-TMD can be adjusted effectively, which can be used to suppress vibrations of tunnel structures under moving trains.

Vibration control of submerged floating tunnel in waves and earthquakes through tuned mass damper

In this study, a passive tuned mass damper (TMD) is investigated to dampen resonant motions of a submerged floating tunnel (SFT) in waves and earthquakes. TMD is adopted to control resonant lateral motion. A time-domain dynamics simulation model that considers the elasticity of the tunnel and mooring lines is first established, which is based on the lumped mass method and Morison equation, and the SFT-TMD interaction is considered through springs and dampers. Next, by using the harmony search (HS) algorithm, TMD's spring and damping coefficients are optimized; the dynamics simulations under white noise seismic excitations are continuously carried out with updated spring and damping coefficients produced by HS rules until the designed maximum iteration number. The influence of TMD's mass is individually investigated through a parametric study. After the optimization process is completed, the global performances of SFT with and without TMD are systematically evaluated in both waves and earthquakes. It is found that TMD plays a crucial role in controlling SFT vibrations when environmental loads are close to the system's fundamental lateral natural frequency under both wave and seismic excitations. TMD also enhances the comfort of passengers and reduces static and dynamic mooring tensions. • A time-domain dynamics simulation model is built for the interaction of a submerged floating tunnel and a tuned mass damper. • The harmony search algorithm shows good optimization performance for the tuning mass damper parameters. • A tuned mass damper effectively reduces resonant motions and mooring tensions under wave and seismic excitations.

Emotional Learning based adaptive control algorithm for Semi-Active seismic control of structures

A tuned mass damper (TMD) is a passive mass-spring system, widely accepted as an effective response control strategy for a structure under external excitation. The inherent passive nature, optimum tuning requirements of TMDs are known to lead to sensitivity problems and/or detuning of the TMDs for changing vibration conditions, limiting their performance to narrow band of input excitation. Due to these limitations, semi-active control concepts are used to introduce adaptability in passive TMDs. Semi-active response control using TMD is much researched in recent years for protection of civil engineering structures against earthquake. In this study, the efficacy of a semi-active mass driver (MD) system coupled with magnetorheological (MR) damper is investigated for seismic response control of a primary structure. The input current to the MR damper in the semi-active MR-MD is controlled using an adaptive Brain Emotional Learning Based Intelligent Controller (BELBIC) control algorithm in a closed loop architecture. The efficiency of the damping addition from the MR damper to the mass driver which is reducing the response of the primary structure is investigated using analytical and simulation studies, considering off-tuning, emulated using three different tuning cases of the MR-MD. From the studies, it is found that semi-active MR-MD is performing satisfactorily in reducing the seismic response of the primary structure and BELBIC algorithm performs efficiently even during off-tuning conditions and presence of physical constraints.

Tuning of passive TMD for floating offshore wind turbine using linear matrix inequalities

Over the last several years, the number of offshore wind turbine installations has increased exponentially. A change from shallow to deep marine waters will be seen in future installations. As we move further away from the shore, the loading on the floating offshore wind turbine (FOWT) system increases. This higher load may have a negative impact on the wind turbine's efficiency. It may also lead to power fluctuations, large tower displacements and increased fatigue loads. In order to circumvent these effects, passive secondary devices are installed. A tuned mass damper (TMD) is one such device that may be utilized for load mitigation. In this paper, an efficient method is presented for the design of TMD for FOWT. The design problem is posed as feedback response control problem for the plant represented by the FOWT-TMD system. The design objective is to evaluate the static controller such that the response of the FOWT is minimized. The controller gains correspond to the TMD properties. The TMD parameters are obtained using iterative LMI, which uses a combination of convex and metaheuristic optimization. The proposed TMD is found to be useful in lowering the FOWT response. The methods described in this paper can be utilized to determine the best TMD configuration.

Design of an Active Damping System for Vibration Control of Wind Turbine Towers

The vibration of wind turbine towers is relevant to the reliability of the wind turbine structure and the quality of power production. It produces both ultimate loads and fatigue loads threatening structural safety. This paper aims to reduce vibration in wind turbine towers using an active damper named the twin rotor damper (TRD). A single degree of freedom (SDOF) oscillator with the TRD is used to approximate the response of wind turbines under a unidirectional gusty wind with loss of the electrical network. The coincidence between the wind gust and the grid loss is studied to involve the maximum loading on the structure. The performance of the proposed damping system under the maximum loading is then evaluated on the state-of-the-art wind turbine NREL 5 MW. The effectiveness of the TRD is compared to a passive tuned mass damper (TMD) designed with similar requirements. The numerical results reveal that, at the 1st natural mode, the TRD outperforms the passive TMD by three to six times. Moreover, the results show that the TRD is effective in reducing ultimate loads on wind turbine towers.

Experimental Testing of Passive Linear TMD for Postural Tremor Attenuation

Research interest to provide a mechanical solution for involuntary tremors is increasing due to the severe side effects caused by the medications used to lessen its symptoms. This paper deals with the design of a cantilever-type tuned mass damper (TMD) used to prove the effectiveness of passive controllers in reducing the involuntary tremor’s vibrational signals transmitted by the muscles to the hand segment. TMD is tested on an experimental arm, reflecting the flexion-extension motion of the wrist, excited by a mechanical shaker with the measured tremor signal of a patient with essential tremor. The designed TMD provides a new operational frequency for each position of the screw fixed to its beam. Modal damping ratios are also calculated using different methods for each position. The effectiveness of the TMD is quantified by measurements using a vibrometer and inertial measurement unit. Three TMDs, representing 15.7% total mass ratio, cause a reduction of 29% for the acceleration, 69% for the velocity, 79% for the displacement, 67% for the angular velocity, and 82% for the angular displacement signals. These encouraging results will allow the improvement of the design of the passive controller in the form of a wearable bracelet suitable for daily life.

Analysis of Load Reduction of Floating Wind Turbines Using Passive Tuned Mass Dampers

Abstract: An efficient method for restraining the large vibration displacements and loads of offshore floating wind turbines under harsh marine environment is proposed by putting tuned mass dampers in the cabin. A dynamics model for a barge-type offshore floating wind turbine with a fore–aft tuned mass damper is established based on Lagrange’s equations; the nonlinear least squares Leven berg–Marquardt algorithm is employed to identify the parameters of the wind turbine; different parameter optimization methods are adopted to optimize tuned mass damper parameters by considering the standard deviation of the tower top longitudinal displacement as the objective function. Aiming at five typical combined wind and wave load cases under normal running state of the wind turbine, the dynamic responses of the wind turbine with/without tuned mass damper are simulated and the suppression effect of the tuned mass damper is investigated over the wide range of load cases. The results show that when the wind turbine vibrates in the state of damped free vibration, the standard deviation of the tower top longitudinal displacement is decreased approximately 60% in 100 s by the optimized tuned mass damper with the optimum tuned mass damper mass ratio 1.8%. The standard deviation suppression rates of the longitudinal displacements and loads in the tower and blades increase with the tuned mass damper mass ratio when the wind turbine vibrates under the combined wind and wave load cases. When the mass ratio changes from 0.5% to 2%, the maximum suppression rates vary from 20% to 50% correspondingly, which effectively reduce vibration responses of the offshore floating wind turbine. The results of this article preliminarily verify the feasibilities of using a tuned mass damper for restraining vibration of the barge-type offshore floating wind turbine

Load Reduction of Floating Wind Turbines Using Tuned Mass Dampers

Abstract: Offshore wind turbines have the potential to be an important part of the United States’ energy production profile in the coming years. In order to accomplish this wind integration, offshore wind turbines need to be made more reliable and cost efficient to be competitive with other sources of energy. To capitalize on high speed and highquality winds over deep water, floating platforms for offshore wind turbines have been developed, but they suffer from greatly increased loading. One method to reduce loadsin offshore wind turbines is the application of structural control techniques usuallyused in skyscrapers and bridges. Tuned mass dampers are one structural control system that have been used to reduce loads in simulations of offshore wind turbines. This thesis adds to the state of the art of offshore wind energy by developing a set of optimum passive tuned mass dampers for four offshore wind turbine platforms and byquantifying the effects of actuator dynamics on an active tuned mass damper design. The set of optimum tuned mass dampers are developed by creating a limited degree-of-freedom model for each of the four offshore wind platforms

Dynamic testing and numerical simulation of human-induced vibration of cantilevered floor with tuned mass dampers

The vibration control of a cantilevered floor with tuned mass dampers (TMDs) was investigated using dynamic testing and numerical simulation methods to better satisfy the structural serviceability requirement. The human-induced vibration response under walking and running conditions were firstly presented based on a series of dynamic testing with a single pedestrian and groups of pedestrians. A fast-evaluated frequency response function (FRF) method suggested by AISC Design Guide 11 was also used to evaluate the vibration response and further verified by the dynamic testing. A passive TMDs system was applied to reduce the vibration response; the vibration control of the cantilevered floor with TMDs was also evaluated by the dynamic testing with a single pedestrian and groups of pedestrians. The results showed that the maximum acceleration response of the cantilevered floor under the running load exceeded the limit, which was on average nine times that of the values under the walking condition. The FRF method could provide a fast and conservative vibration evaluation, in which the maximum acceleration response was 26% higher than that from dynamic testing. The acceleration response was significantly reduced with a maximum reduction effect of 64% after the installation of TMDs, resulting in satisfactory vibration serviceability of the cantilevered floor; the numerical simulation of that agreed well with the dynamic testing results. The vibration control of the cantilevered floor as a case study can serve as reference for the application of TMDs.