Control Concepts of Semi-Active Friction Dampers

2009 ◽  
Author(s):  
Lothar Gaul ◽  
Jens Becker
Keyword(s):  
Active Control ◽  
Relative Displacement ◽  
Structural Vibration ◽  
Control Algorithms ◽  
Friction Damper ◽  
Control Laws ◽  
Friction Dampers ◽  
Closed Loop Systems ◽  
Major Interest ◽  
Improving Accuracy

Reduction of structural vibrations is of major interest in mechanical engineering for lowering sound emission of vibrating structures, improving accuracy of machines and increasing structure durability. Besides design optimization and passive damping treatments, active structural vibration control can be applied to reduce unwanted vibrations. In this contribution, two semi-active control laws for control of friction dampers are derived and investigated in simulations and experiments. Thereby, semi-active control concepts have the advantage over active control to yield intrinsically stable closed-loop systems and low energy consumption. In the experimental implementation, the control makes use of piezoelectric stack actuators to apply adjustable normal forces between structure and attached friction dampers. The control uses an observer based on reduced finite-element models to estimate the unknown relative displacement beneath the normal force actuator from acceleration measurements. Experimental results of the control algorithms for a structure with attached friction damper show the effectiveness of the proposed control algorithms.

Vibration Reduction by Passive and Semi-Active Friction Joints

2011 ◽  
Author(s):  
Lothar Gaul ◽  
Jens Becker
Keyword(s):  
Active Control ◽  
Mechanical Design ◽  
Vibration Reduction ◽  
Structural Vibration ◽  
Friction Damper ◽  
Friction Dampers ◽  
Structural Vibration Control ◽  
Experimental Implementation ◽  
Major Interest ◽  
Improving Accuracy

Reduction of structural vibrations is of major interest in mechanical engineering for lowering sound emission of vibrating structures, improving accuracy of machines and increasing structure durability. Besides optimization of the mechanical design or various types of passive damping treatments, active structural vibration control concepts are efficient means to reduce unwanted vibrations. In this contribution, two different semi-active control concepts for vibration reduction are proposed that adapt the normal force of attached friction dampers. Thereby, semi-active control concepts generally possess the advantage over active control that the closed loop is intrinsically stable and that less energy is required for the actuation than in active control. In the chosen experimental implementation, a piezoelectric stack actuators is used to apply adjustable normal forces between a structure and an attached friction damper. Simulation and experimental results of a benchmark structure with passive and semi-actively controlled friction dampers are compared for stationary narrow-band excitation.

scholarly journals Reduction of Structural Vibrations by Passive and Semiactively Controlled Friction Dampers

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
L. Gaul ◽  
J. Becker
Keyword(s):  
Finite Element ◽  
Active Control ◽  
Constitutive Laws ◽  
Structural Vibration ◽  
Semiactive Control ◽  
Friction Damper ◽  
Structural Vibrations ◽  
Normal Contact ◽  
Friction Dampers ◽  
Major Interest

Reduction of structural vibrations is of major interest in mechanical engineering for lowering sound emission of vibrating structures, improving accuracy of machines, and increasing structure durability. Besides optimization of the mechanical design or various types of passive damping treatments, active structural vibration control concepts are efficient means to reduce unwanted vibrations. In this contribution, two different semiactive control concepts for vibration reduction are proposed that adapt to the normal force of attached friction dampers. Thereby, semiactive control concepts generally possess the advantage over active control in that the closed loop is intrinsically stable and that less energy is required for the actuation than in active control. In the chosen experimental implementation, a piezoelectric stack actuator is used to apply adjustable normal forces between a structure and an attached friction damper. Simulation and experimental results of a benchmark structure with passive and semiactively controlled friction dampers are compared for stationary narrowband excitation. For simulations of the control performance, transient simulations must be employed to predict the achieved vibration damping. It is well known that transient simulation of systems with friction and normal contact requires excessive computational power due to the nonlinear constitutive laws and the high contact stiffnesses involved. However, commercial finite-element codes do not allow simulating feedback control in a general way. As a remedy, a special simulation framework is developed which allows efficiently modeling interfaces with friction and normal contact by appropriate constitutive laws which are implemented by contact elements in a finite-element model. Furthermore, special model reduction techniques using a substructuring approach are employed for faster simulation.

scholarly journals SEMI-ACTIVE PREDICTIVE CONTROL OF STRUCTURES WITH CONTROLLED STIFFNESS DEVICES AND VARIABLE FRICTION DAMPER SYSTEM

2010 ◽  
Vol 13 (4) ◽  
pp. 64-73
Author(s):  
Thang Quoc Chu ◽  
Hoa Nhan Pham ◽  
Ben Van Tran
Keyword(s):  
Active Control ◽  
Predictive Control ◽  
Control Algorithms ◽  
Friction Damper ◽  
Velocity Feedback ◽  
Numerical Examples ◽  
Acceleration Feedback ◽  
Variable Friction ◽  
Instantaneous Control

This paper presents two active control algorithms (Instantaneous Control with Displacement and Velocity Feedback (ICDVF) and Instantaneous Control with Velocity and Acceleration Feedback (ICAVF)) to control the structures eqquiped Controlled Stiffness Devices and Variable Friction Damper System. The numerical examples aim to evaluate the effect structure’s response reductions between the two algorithms as well as the principal and accessory role.

A method for bidirectional active control of structures

2017 ◽  
Vol 24 (15) ◽  
pp. 3400-3417 ◽  
Author(s):  
Satyam Paul ◽  
Wen Yu
Keyword(s):  
Vibration Control ◽  
Active Control ◽  
Active Vibration Control ◽  
Sufficient Conditions ◽  
Industrial Applications ◽  
Structural Vibration ◽  
Pid Controllers ◽  
Control Algorithms ◽  
Structural Vibration Control ◽  
Active Vibration

Proportional-derivative (PD) and proportional-integral-derivative (PID) controllers are popular control algorithms in industrial applications, especially in structural vibration control. In this paper, the designs of two dampers, namely the horizontal actuator and torsional actuator, are combined for the lateral and torsional vibrations of the structure. The standard PD and PID controllers are utilized for active vibration control. The sufficient conditions for asymptotic stability of these controllers are validated by utilizing the Lyapunov stability theorem. An active vibration control system with two floors equipped with a horizontal actuator and a torsional actuator is installed to carry out the experimental analysis. The experimental results show that bidirectional active control has been achieved.

Semiactive Wind Response Control of 76-Story Benchmark Building with Smart Piezoelectric Friction Dampers

2011 ◽  
Vol 250-253 ◽  
pp. 2196-2201 ◽  
Author(s):  
Ping Dong ◽  
Jian Fan
Keyword(s):  
Control System ◽  
Active Control ◽  
Simulation Analysis ◽  
Force Model ◽  
Friction Damper ◽  
Damping Force ◽  
Friction Dampers ◽  
Benchmark Model ◽  
Active Control System ◽  
Wind Induced Vibration

A smart piezoelectric friction damper (SPFD) is presented based on improved Pall friction dampers and its damping force model is analyzed. The wind-induced vibration control of Benchmark model using semi-active control strategies based on the classical LQR is studied. The results of simulation analysis show that the semi-active control effects of the standard wind-control model with SPFD is evident. Compared to uncontrolled structures, the wind-induced vibration responses of the controlled structures are effectively reduced. In addition, parameter optimization of the semi-active control system based on the limit Hrovat optimal control algorithm is carried out. The analysis shows that the robustness of the semi-active control system to the stiffness uncertainty of Benchmark Model is very good, but the robustness to the damping uncertainty is not so good.

Optimization of Interblade Friction Damper Design

2000 ◽  
Author(s):  
Lars Panning ◽  
Walter Sextro ◽  
Karl Popp
Keyword(s):  
Equations Of Motion ◽  
Turbine Blades ◽  
Relative Displacement ◽  
Contact Forces ◽  
Hertzian Contact ◽  
Computation Method ◽  
Friction Damper ◽  
Friction Dampers ◽  
Advantages And Disadvantages ◽  
Bladed Disk

The vibration amplitudes of bladed disk assemblies can be reduced significantly by means of friction damping devices such as shrouds, damping wires and interblade friction dampers. In practice, interblade friction dampers are applied in rotating arrangements with various geometries showing curved or flat surfaces like so-called wedge-shaped dampers. This paper is focusing on a computation method to predict the dynamical behaviour of turbine blades with friction dampers including both, curved and wedge-shaped dampers with Hertzian and non-Hertzian contact conditions, respectively. The presented computation method uses a 3D contact model to calculate the contact forces, including normal and tangential stiffnesses, roughness and microslip effects. The relative displacements in the contact area can be expressed by means of 6 DOF of the blade platforms and 6 rigid body DOF of the damper including translational and rotational displacements. The relative displacement of the friction damper with respect to the adjacent blades can be derived from the contact kinematics of the blade-damper-blade system and the equations of motion of the friction damper. Thus, the model can be applied to investigate spatial motions of the bladed disk assembly including bending and torsional vibrations. A comparison of different friction damper designs with respect to an optimal damper geometry and damper mass is presented. The advantages and disadvantages of each design will be discussed. Experimental results are shown to validate the developed computation method.

The Use of Damping Based Semi-Active Control Algorithms in the Mechanical Smart-Spring System

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Wander Gustavo Rocha Vieira ◽  
Fred Nitzsche ◽  
Carlos De Marqui
Keyword(s):  
Active Control ◽  
Control Algorithm ◽  
Control Strategies ◽  
Vibration Reduction ◽  
Flow Analysis ◽  
Coupled Systems ◽  
Control Technique ◽  
Control Algorithms ◽  
Control Techniques ◽  
Spring Mechanism

In recent decades, semi-active control strategies have been investigated for vibration reduction. In general, these techniques provide enhanced control performance when compared to traditional passive techniques and lower energy consumption if compared to active control techniques. In semi-active concepts, vibration attenuation is achieved by modulating inertial, stiffness, or damping properties of a dynamic system. The smart spring is a mechanical device originally employed for the effective modulation of its stiffness through the use of semi-active control strategies. This device has been successfully tested to damp aeroelastic oscillations of fixed and rotary wings. In this paper, the modeling of the smart spring mechanism is presented and two semi-active control algorithms are employed to promote vibration reduction through enhanced damping effects. The first control technique is the smart-spring resetting (SSR), which resembles resetting control techniques developed for vibration reduction of civil structures as well as the piezoelectric synchronized switch damping on short (SSDS) technique. The second control algorithm is referred to as the smart-spring inversion (SSI), which presents some similarities with the synchronized switch damping (SSD) on inductor technique previously presented in the literature of electromechanically coupled systems. The effects of the SSR and SSI control algorithms on the free and forced responses of the smart-spring are investigated in time and frequency domains. An energy flow analysis is also presented in order to explain the enhanced damping behavior when the SSI control algorithm is employed.

scholarly journals Improved Reliability of Bladed Disks due to Friction Dampers

1997 ◽  
Author(s):  
Walter Sextro ◽  
Karl Popp ◽  
Ivo Wolter
Keyword(s):  
Dry Friction ◽  
Three Dimensional ◽  
Line Contact ◽  
Two Dimensional ◽  
Centrifugal Forces ◽  
Friction Damper ◽  
Blade Vibration ◽  
Friction Dampers ◽  
Bladed Disk ◽  
Bladed Disk Assembly

Friction dampers are installed underneath the blade platforms to improve the reliability. Because of centrifugal forces the dampers are pressed onto the platforms. Due to dry friction and the relative motion between blades and dampers, energy is dissipated, which results in a reduction of blade vibration amplitudes. The geometry of the contact is in many cases like a Hertzian line contact. A three-dimensional motion of the blades results in a two-dimensional motion of one contact line of the friction dampers in the contact plane. An experiment with one friction damper between two blades is used to verify the two-dimensional contact model including microslip. By optimizing the friction dampers masses, the best damping effects are obtained. Finally, different methods are shown to calculate the envelope of a three-dimensional response of a detuned bladed disk assembly (V84.3-4th-stage turbine blade) with friction dampers.

Frequency Shaped Semi-Active Control for Magnetorheological Fluid-Based Vibration Control Systems

2013 ◽  
Author(s):  
Young-Tai Choi ◽  
Norman M. Wereley ◽  
Gregory J. Hiemenz
Keyword(s):  
Vibration Control ◽  
Control Systems ◽  
Active Control ◽  
Control Algorithm ◽  
Active Vibration Control ◽  
Control Algorithms ◽  
Model Parameters ◽  
Mr Fluid ◽  
Control Current ◽  
Active Vibration

Novel semi-active vibration controllers are developed in this study for magnetorheological (MR) fluid-based vibration control systems, including: (1) a band-pass frequency shaped semi-active control algorithm, (2) a narrow-band frequency shaped semi-active control algorithm. These semi-active vibration control algorithms designed without resorting to the implementation of an active vibration control algorithms upon which is superposed the energy dissipation constraint. These new Frequency Shaped Semi-active Control (FSSC) algorithms require neither an accurate damper (or actuator) model, nor system identification of damper model parameters for determining control current input. In the design procedure for the FSSC algorithms, the semi-active MR damper is not treated as an active force producing actuator, but rather is treated in the design process as a semi-active dissipative device. The control signal from the FSSC algorithms is a control current, and not a control force as is typically done for active controllers. In this study, two FSSC algorithms are formulated and performance of each is assessed via simulation. Performance of the FSSC vibration controllers is evaluated using a single-degree-of-freedom (DOF) MR fluid-based engine mount system. To better understand the control characteristics and advantages of the two FSSC algorithms, the vibration mitigation performance of a semi-active skyhook control algorithm, which is the classical semi-active controller used in base excitation problems, is compared to the two FSSC algorithms.

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