Cycle energy control of magnetorheological dampers on cables

SUMMARYA negative stiffness damper (NSD) is proposed, and its performance on suppressing stay cable vibrations is investigated by numerical simulations and experimental tests. First, the NSD consists of two pressed springs and an oil damper. The two pressed springs are attached perpendicularly to the piston rod of the oil damper in symmetrical configuration. Mechanical model of this damper is derived according to the geometrical configuration and validated experimentally. Considering the simplified model of single-mode vibration of a cable, the cable frequency with the NSD is investigated theoretically by average method, and the lower limit on the pressed degree of two springs is proposed. Numerical examples of cable with NSD and oil damper under sinusoidal excitations are conducted. The NSD shows the superior reduction performance of both amplitudes in time history and peak values of frequency response. A series of single-mode and multi-mode cable vibration control experiments are carried out to evaluate mitigation performance achieved by the NSD. The results indicate that this NSD can provide larger additional modal damping ratio to the cable regardless of single-mode and multiple-mode vibration. Thus, this NSD achieves further reduction of the cable than the oil damper through negative stiffness behavior, instead of complex active or semi-active devices with real-time feedback.

“…A linear viscous damper with the optimal coefficient is assumed to be attached at location x d / L = 2 %. The harmonic excitation of the first mode of the cable is similar to

f_{w} ((),, x, t) = ({, \begin{array}{c} center & 0.6 normalsin ((), π x true/ L) normalsin ((), ω_{1} t) & t ⩽ 10 normals \\ center & 0 & t > 10 normals \end{array})

…”

Section: Numerical Simulation On Control Of Stay Cable Vibration Usinmentioning

confidence: 99%

“…However, the current driver is necessary to control the MR damper in real time. To avoid the using of current driver, amplitude‐independent and frequency‐independent cycle energy control by MR dampers have been studied and applied in some bridges by Weber et al .…”

Section: Introductionmentioning

confidence: 99%

Modeling and control performance of a negative stiffness damper for suppressing stay cable vibrations

Zhou

2015

“…This observation is in agreement with the numerical analysis of a taut string with uncontrolled friction damper as shown in and the experimental results shown in . It is therefore concluded that the predominant friction force must be controlled depending on the actual vibration state of the cable as shown in where a controllable friction damper was used. If c mr ≠ 0 , the friction force must also be controlled to avoid the aforementioned drawbacks.…”

Section: Magnetorheological Damper In Passive Modementioning

confidence: 99%

Amplitude and frequency independent cable damping of Sutong Bridge and Russky Bridge by magnetorheological dampers

Weber

Distl

2014

SUMMARY Two control approaches for magnetorheological (MR) dampers on cables based on collocated control without state estimation are formulated, which generate amplitude and frequency independent cable damping: cycle energy control and controlled viscous damping (CVD). The force tracking is solved by the inverted Bingham model whose parameters are fitted as function of current and frequency. Cycle energy control and CVD are experimentally validated by hybrid simulations and free decay tests on stay cables of the Sutong Bridge, China, and the Eiland Bridge, the Netherlands. The implementation of CVD on the Russky Bridge, Russia, includes two novelties: the force tracking also takes the actual MR damper temperature into account to ensure precise force tracking for MR damper temperatures −40 to +60 °C and the decentralised real‐time control units with pulse width current modulation are installed next to each MR damper to avoid long direct current (DC) power lines with associated losses and thereby minimise power consumption. Copyright © 2014 John Wiley & Sons, Ltd.

“…Magnetorheological (MR) dampers have been used for controlled structural damping because these semi‐active devices provide the possibility to combine the advantages of passive and active control, and the residual force at 0 A ensures some failsafe performance during a power break down . As shown in, for example, , MR dampers have been successfully used for controlled damping and optimal control of stay cables. Similar numerical and experimental investigations including hybrid testing were conducted in, for example, , for the vibration reduction of buildings equipped with controlled MR dampers.…”

Section: Introductionmentioning

confidence: 99%

Extended neural network-based scheme for real-time force tracking with magnetorheological dampers

Weber

Bhowmik

Høgsberg

2013

This paper validates numerically and experimentally a new neural network-based real-time force tracking scheme for magnetorheological (MR) dampers on a five-storey shear frame with MR damper. The inverse model is trained with absolute values of measured velocity and force because the targeted current is a positive quantity. The validation shows accurate results except of small current spikes when the desired force is in the vicinity of the residual MR damper force. In the closed-loop, higher frequency components in the current are triggered by the transition of the actual MR damper force from the pre-yield to the post-yield region. A control-oriented approach is presented to compensate for these drawbacks. The resulting control force tracking scheme is validated for the emulation of viscous damping, clipped viscous damping with negative stiffness, and friction damping with negative stiffness.The tests indicate that the proposed tracking scheme works better when the frequency content of the estimated current is close to that of the training data. The LuGre friction model was adopted as observer in [18] to solve the force tracking task. This short review on existing real-time force tracking schemes shows that the nonmodel-based Heaviside step function approach only works with force feedback; the Dahl model leads to precise current estimation only in special cases, and the LuGre friction model can only be used as observer because this approach cannot be inverted. In this study, the real-time force tracking task without force feedback is therefore investigated by the adoption of soft-computing techniques that allow modeling the inverse MR damper dynamics directly and thereby circumvent the aforementioned drawbacks.Besides the fuzzy logic approach that is used in [19] to directly estimate the inverse MR damper behavior, the neural network method is seen to be able to capture the nonlinear inverse MR damper dynamics. Recurrent neural network models were constructed in [20] to emulate both the forward and inverse MR damper dynamics. Both models take the previous values of the estimated force and voltage, respectively, as inputs among other states. The validation of the inverse model shows some high frequency spikes in the estimated voltage. In the work of Xia [21], the inverse MR damper behavior was modeled by using a multilayer perceptron optimal neural network and system identification. The inverse model is trained and validated with simulated data taking into account the previous values of the voltage. The authors of [22] studied the modeling of the inverse MR damper dynamics using feedforward and recurrent neural networks. For the targeted constant voltage of 1.5 V, the predicted voltage showed spikes of up to AE0.17 V at a frequency that seems to be equal to the damper motion frequency. If the targeted voltage is a sinusoidal function with constant frequency, the time history of the estimated voltage does not describe a pure sine, and thereby, the resulting error is larger than AE0.17 V. In contrast, the forward mo...