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.

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.

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 Vibration Antiresonance Design for a Spacecraft Multifunctional Structure

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Dong-Xu Li ◽  
Wang Liu ◽  
Dong Hao
Keyword(s):  
Design Method ◽  
Structural Parameters ◽  
Vibration Reduction ◽  
Zero Point ◽  
Thermal Control ◽  
Structural Vibration ◽  
Load Bearing ◽  
Structural Vibration Control ◽  
Complex Zero ◽  
Noise Vibration

Spacecraft must withstand rigorous mechanical environment experiences such as acceleration, noise, vibration, and shock during the process of launching, satellite-vehicle separation, and so on. In this paper, a new spacecraft multifunctional structure concept designed by us is introduced. The multifunctional structure has the functions of not only load bearing, but also vibration reduction, energy source, thermal control, and so on, and we adopt a series of viscoelastic parts as connections between substructures. Especially in this paper, a vibration antiresonance design method is proposed to realize the vibration reduction. The complex zero-point equations of the vibration system are firstly established, and then the vibration antiresonance design for the system is achieved. For solving the difficulties due to viscoelastic characteristics of the connecting parts, we present the determining formulas to obtain the structural parameters, so that the complex zero-point equations can be satisfied. Numerical simulation and ground experiment demonstrate the correctness and effectiveness of the proposed method. This method can solve the structural vibration control problem under the function constraints of load bearing and energy supplying and will expand the performance of spacecraft functional modules.

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.

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.

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