MR Damper Controlled Vibration Absorber for Enhanced Mitigation of Harmonic Vibrations

Abstract

This paper describes a semi-active vibration absorber (SVA) concept based on a real-time controlled magnetorheological damper (MR-SVA) for the enhanced mitigation of structural vibrations due to harmonic disturbing forces. The force of the MR damper is controlled in real-time to generate the frequency and damping controls according to the behaviour of the undamped vibration absorber for the actual frequency of vibration. As stiffness and damping emulations in semi-active actuators are coupled quantities the control is formulated to prioritize the frequency control by the controlled stiffness. The control algorithm is augmented by a stiffness correction method ensuring precise frequency control when the desired control force is constrained by the semi-active restriction and residual force of the MR damper. The force tracking task is solved by a model-based feed forward with feedback correction. The MR-SVA is numerically and experimentally validated for the primary structure with nominal eigenfrequency and when de-tuning of −10%, −5%, +5% and +10% is present. Both validations demonstrate that the MR-SVA improves the vibration reduction in the primary structure by up to 55% compared to the passive tuned mass damper (TMD). Furthermore, it is shown that the MR-SVA with only 80% of tuned mass leads to approximately the same enhanced performance while the associated increased relative motion amplitude of the tuned mass is more than compensated be the reduced dimensions of the mass. Therefore, the MR-SVA is an appropriate solution for the mitigation of tall buildings where the pendulum mass can be up to several thousands of metric tonnes and space for the pendulum damper is limited.

A Review on Parametric Dynamic Models of Magnetorheological Dampers and Their Characterization Methods

“…In [45] a non-symmetric hysteretic response of Force/Velocity data has been reported, especially near the zero velocity (shifted Hysteresis). To take account of this phenomenon the expression ofż changed to z = (A − (β + γsgn(zẋ))|z| n )ẋ (22) and:ẋ = (ẋ − µsgn(x)) (23) So (22) became:…”

Curved surface sliders with friction damping, linear viscous damping, bow tie friction damping, and semiactively controlled properties

“…The stiffness emulation in semiactive dampers is realized by the modulation of their dissipative force during each half cycle . The controlled stiffness emulated by semiactive dampers therefore only exists under dynamic conditions, whereby it is denoted as “dynamic”; other publications use the term “pseudo.” It is suggested to use the term “dynamic” because the emulated stiffness is a physical quantity that can be measured under dynamic conditions, but it does not exist under static conditions.…”

“…The concept to split the total restoring stiffness into one passive part and one controlled part is proposed because then the maximum negative dynamic stiffness is only −( N S / R eff /2), which improves the emulation accuracy as stiffness emulation in semiactive dampers is constrained …”

Piezoelectric Plates Distribution for Active Control of Torsional Vibrations

“…The first one is simpler and less expensive but has a small bandwidth. The second one has a large bandwidth and can adapt the damping to time-dependent loads so that they turn out to be more efficient [1][2][3][4]. In recent years, the development of the smart materials for application in damping systems has made considerable progress and among these, the piezoelectric materials have a great adaptability [5][6][7][8][9][10][11][12].…”