Dynamic Response Control Research Articles

아웃리거 댐퍼 시스템의 고층건물 풍응답 진동제어 성능 평가

Recently, the concept of damped outrigger system has been proposed for tall buildings. But, structural characteristics and design method of this system were not sufficiently investigated to date. In this study, the dynamic response control performance of outrigger damper has been analyzed. To this end, a simplified analysis model with outrigger damper system has been developed. An artificial wind of 1000 seconds with 0.1 second time steps was generated by using a Kaimal spectrum. Analysis results show that outrigger damper system is more effective up to 20-23% in the control of dynamic response compared to conventional outrigger system. The increase of outrigger damper capacity usually results in the improved control performance. However, it is necessary to select that proper stiffness and damping values of the outrigger damper system because, the outrigger damper having large capacity is result in heavy financial burden.

Performance of a Single Liquid Column Damper for the Control of Dynamic Responses of a Tension Leg Platform

Tuned liquid column dampers have been proved to be successful in mitigating the dynamic responses of civil infrastructure. There have been some recent applications of this concept on wind turbines and this passive control system can help to mitigate responses of offshore floating platforms and wave devices. The control of dynamic responses of these devices is important for reducing loads on structural elements and facilitating operations and maintenance (O&M) activities. This paper outlines the use of a tuned single liquid column damper for the control of a tension leg platform supported wind turbine. Theoretical studies were carried out and a scaled model was tested in a wave basin to assess the performance of the damper. The tests on the model presented in this paper correspond to a platform with a very low natural frequency for surge, sway and yaw motions. For practical purposes, it was not possible to tune the liquid damper exactly to this frequency. The consequent approach taken and the efficiency of such approach are presented in this paper. Responses to waves of a single frequency are investigated along with responses obtained from wave spectra characterising typical sea states. The extent of control is quantified using peak and root mean squared dynamic responses respectively. The tests present some guidelines and challenges for testing scaled devices in relation to including response control mechanisms. Additionally, the results provide a basis for dictating future research on tuned liquid column damper based control on floating platforms.

Nonlinear dynamic response and active control of fiber metal laminated plates with piezoelectric actuators and sensors in unsteady temperature field

Based on the higher order shear deformation theory and the geometric nonlinear theory, the nonlinear motion equations, to which the effects of the positive and negative piezoelectric and the thermal are introduced by piezoelectric fiber metal laminated (FML) plates in an unsteady temperature, are established by Hamilton’s variational principle. Then, the control algorithm of negative-velocity feedback is applied to realize the vibration control of the piezoelectric FML plates. During the solving process, firstly, the formal functions of the displacements that fulfilled the boundary conditions are proposed. Then, heat conduction equations and nonlinear differential equations are dealt with using the differential quadrature (DQ) and Galerkin methods, respectively. On the basis of the previous processing, the time domain is dispersed by the Newmark-β method. Finally, the whole problem can be investigated by the iterative method. In the numerical examples, the influence of the applied voltage, the temperature loading and geometric parameters on the nonlinear dynamic response of the piezoelectric FML plates is analyzed. Meanwhile, the effect of feedback control gain and the position of the piezoelectric layer, the initial deflection and the external temperature on the active control effect of the piezoelectric layers has been studied. The model development and the research results can serve as a basis for nonlinear vibration analysis of the FML structures.

Application of Concrete Segment Panels for Reduction of Torsional Vibration Responses of Girder Bridges

The dynamic flexural behaviour of railway bridges is influenced by the torsional behaviour, and the flexural response tends to be amplified as the flexural natural frequency (the 1st vibrational mode) and torsional frequency (the 2nd vibrational mode) are adjoining. To avoid this phenomenon, the installation of concrete segment panels was considered for the reinforcement of torsional stiffness by connecting bottom flanges between girders. This alternative can increase the torsional stiffness by providing the restraint in torsional vibration and reduce the influence of torsional behaviour on the amplification of flexural responses. This study investigates the effect of the concrete segment panels on the control of torsional dynamic responses and on the increment of torsional frequency. The excitation tests on a full-size bridge specimen with 30 m span length were conducted with respect to the installation length of concrete panels up to 7 m from each ends. The results show that the installation of concrete segment panel augments the torsional frequency up to 22 % while the flexural frequency keeps its original value. It is concluded that the dynamic behaviour of girder bridges can be controlled by the adjustment of installation length of concrete panels, thereby reducing the torsional responses.

Parameter Design and Static Performance Analysis of a Novel Axial Magnetic Bearing for Maglev Wind Generators

As an important component of maglev wind generators, magnetic bearing should possess the merits of small volume, light weight, lower consumption and so on. A novel low-loss axial hybrid magnetic bearing (HMB) is proposed in this paper, its structure and operation principle are introduced, and the process of producing suspension force is elaborated. Based on equivalent magnetic circuit method, magnetic circuit models of PM and control coil are analyzed and established to deduce the quotation of axial levitation force. The accuracy and the reasonableness of proposed low-loss axial HMB are analyzed and validated by using finite element method (FEM), and the comparison between theoretical calculation and FEM is given, which indicates the proposed HMB exhibits good dynamic response and easy control.

Active shape and vibration control for piezoelectric bonded composite structures using various geometric nonlinearities

This paper deals with simulations of the static and dynamic response, including shape and vibration control, for piezoelectric bonded smart structures using various geometrically nonlinear shell theories based on the first-order shear deformation (FOSD) hypothesis. The nonlinear theories include refined von Kármán nonlinear shell theory (RVK5), moderate rotation shell theory (MRT5), fully geometrically nonlinear shell theory with moderate rotations (LRT5), and fully geometrically nonlinear shell theory with large rotations (LRT56). The structures simulated are mainly comprised of cross-ply or angle-ply laminated thin-walled master structures bonded with isotropic piezoelectric layers or patches that are considered as actuators. Nonlinear finite element (FE) models are constructed for shape and vibration control of structures undergoing large displacements and rotations. Various plates and shells are validated by comparison with those reported in the literature, and then simulated for the current shape and vibration control. A widely used negative proportional velocity feedback control is adopted for the active vibration control. From the simulations, it can be concluded that large rotation theory should be considered for structures undergoing deformations beyond the range of moderate rotations. Additionally, the results show that by applying an appropriate voltage, a desired shape can be achieved, as well as the vibration can be significantly suppressed.

Sliding Mode Control of Three-Phase Four-Leg Inverters via State Feedback

To optimize controller design and improve static and dynamic performances of three-phase four-leg inverter systems, a compound control method that combines state feedback and quasi-sliding mode variable structure control is proposed. The linear coordinate change matrix and the state variable feedback equations are derived based on the mathematical model of three-phase four-leg inverters. Based on system relative degrees, sliding surfaces and quasi-sliding mode controllers are designed for converted linear systems. This control method exhibits the advantages of both state feedback and sliding mode control. The proposed controllers provide flexible dynamic control response and excellent stable control performance with chattering suppression. The feasibility of the proposed strategy is verified by conducting simulations and experiments.

Dynamic Response Control of Rotating Thin-Walled Composite Blade Exposed to External Excitations

AbstractA study of the dynamic control of a rotating blade subjected to external excitations is presented. A tapered thin-walled beam of closed cross-section contour with fiber-reinforced composite material is used for present study. Since a rotating blade may be exposed to a severe environment such as high angular velocity, large external load, and so on, robust control methodology is implemented to extend the blade’s life and improve its efficiency. To verify the performance of the state estimator, a sliding mode observer is introduced, and an associated robustness test is conducted in case of model uncertainty. A robust control methodology using sliding mode control in conjunction with a sliding mode observer is implemented, and its performance toward reducing the flapping dynamic responses of a rotating blade under initial conditions and various external loadings such blast load and distributed load is demonstrated. Moreover, its control performance is compared with that of the conventional linear qua...

Simplified Reactive Power Control for Single-Phase Grid-Connected Photovoltaic Inverters

The objective of this paper is to propose a simplified reactive power control (SRPC) strategy for single-phase grid-tied photovoltaic (PV) inverters. With the proposed SRPC strategy, a cost-effective microcontroller can be adopted to achieve an effectively reactive power control. Moreover, the current-mode asynchronous sigma-delta modulation (CASDM) is adopted to enhance the current control's dynamic response and reduce both the current harmonic distortion and electromagnetic interference. In this paper, the operational principle of the proposed SRPC is introduced. Then, the small signal analysis for the PV inverter with the CASDM is presented. Finally, a 1-kVA single-phase PV inverter was built to verify the performance of the proposed control strategy.

Dynamic Response Control of Asymmetric Systems with Load Interference

The article based on the valve driving servo system of 125MN hydraulic press extruder, aimed at solving the unconformity of the dynamic property in electromechanical integration equipment or control system. It analyzed the mathematical model of the system, the influencing parameter and the regularity related to the asymmetric characteristics, when the cylinder moving forward and reverse direction. According the application in industry field, it adopts the methods by adjusting the ratio of the proportion parameters to remove the asymmetric characteristics in different direction and different loads.

Active control of dynamic frequency responses for shell structures

The active control method is a popular way to control mechanical vibration. However, for some industrial needs and military requirements, it does not only need to control vibration, but also has to change the online constant working frequency responses, for example to improve the dynamic performance of mechanical devices and the stealth of military equipment. Because the present active control methods mainly focus on vibration control, the dynamic frequency responses active control method (DFRACM) is constructed to deal with this problem. The constructed DFRACM can not only accomplish vibration control but can also arbitrarily change the dynamic frequency responses of mechanical equipment. Besides, in order to satisfy engineering requirements, the multi-objective DFRACM, which can control the dynamic frequency responses of the controlled object to reach separate specific objectives at different places in one time, is also studied in this paper. The effectiveness of the constructed method is verified through experiments of the open cylindrical shell structure.

Matrix converter for static synchronous series compensator using cooperative bacteria foraging optimisation

Static synchronous series compensator (SSSC) is utilised for power flow control and reactive power compensation in transmission lines. In this paper, a new configuration of SSSC based on matrix converter is presented. The proposed SSSC has various advantages over traditional one. It is recognised by bi-directional power flow control capability, elimination of the DC-link, fast dynamic response and simple control system. Using the introduced switching algorithm for ac/ac matrix converter, an approximately sinusoidal series compensation voltage is injected to transmission line with low total harmonic distortion. The optimal parameters of power flow controller are achieved by using cooperative bacterial foraging optimisation. The proposed SSSC is tested at different operating condition by using MATLAB/Simulink software. Results show that the designed control strategy with the new SSSC topology is robust against sudden changes in active and reactive power flow. As well as, it copes significantly with symmetrical and asymmetrical faults conditions. Finally, measurements of system performance validate the proposed technique and emphasise its feasibility.

Research of High Speed Spindle Control Method Based on Neural Network

High speed spindle is a multivariable and strong coupling complex system. In order to improve its dynamic response characteristics and control effectively, based on vector control, the high speed spindle needs to be decoupling first. Then neural network theory and BP algorithm are adopted to form a speed controller to adjust the rotational speed. In this controller, gradient searching technique is applied and the proportional and integral parameters are used as weight of neural network which is employed to adjust the corresponding control parameters. Therefore, a new model of high speed spindle is set up and simulated. The result of simulation indicates that the way combine the decoupling method and the speed controller based on neural network can track the rotational speed more accurate and promote the robustness of high speed spindle.

The Vibration Control Research of Steel Frame Structure with Shape Memory Alloy (SMA) Cables

The dynamic response control for a three layer steel frame structure with shape memory alloy (SMA) cables under seismic ground motions was studied experimentally in the paper. A three-story steel frame structure model assembling the diagonal SMA cables was tested in a shaking table. The maximum acceleration and displacement of each layer of the steel frame structure were tested under two cases: assembling with SMA cables or not. The experimental result shows that the maximum acceleration and displacement of each layer are significantly reduced by assembling the SMA cables. The vibration responses of the steel frame structure had been greatly reduced by the great dissipation efficiency for SMA dampers.

Dynamic response and microstructure control of Al–Sc binary alloy under high-speed impact

It is concluded that the secondary Al3Sc particles play a predominant role on the high-speed impact process. The secondary Al3Sc particles have two effects of stabilizing the matrix structure and acting as source of dislocation. Because the capability of Al–Sc alloy to resist high-speed projectile impact is related to the microstructure, the development of Al–Sc alloy with a combination of fine-grain strengthening and precipitation strengthening is investigated. The results show that Sc additions greater than the eutectic composition (0.55wt%) were found to produce a remarkable refinement in the grain size. Discontinuous precipitations, which are undesired, are prone to occur in the hypereutectic Al–Sc alloys. For the hypereutectic Al–Sc alloys, control of the aging temperature within a certain range can suppress the presence of discontinuous precipitation, thus the Al–Sc alloy can be strengthened by both the fine-grain strengthening and by continuous precipitation strengthening, which helps to improve the capability to resist high-speed impact.

Nonlinear Identification of a Magneto‐Rheological Damper Based on Dynamic Neural Networks

AbstractSemi‐active control of dynamic response of civil structures with magneto‐rheological (MR) fluid dampers has emerged as a novel revolutionary technology in recent years for designing “smart structures.” A small‐scale MR damper model with the valve mode mechanism has been examined in this research using dynamic recurrent neural network modeling approach to reproduce its hysteretic nonlinear behavior. Modified Bouc–Wen model based on nonlinear differential equations has not only been employed as the reference model to provide a comprehensive training data for the neural network but also for comparison purposes. A novel frequency and amplitude varying displacement input signal (modulated chirp signal) associated with a random supply voltage has been introduced for persistent excitation of the damper in such a way to cover almost all of its operating conditions. Finally a series of validation tests were conducted on the proposed model which proved the appropriate performance of the model in terms of accuracy and capability for realization.

THE SIMULATION OF HYSTERESIS DIRECT TORQUE CONTROL OF PERMANENT MAGNET SYNCHRONOUS MOTOR

In parallel to the recent developments in microprocessors technology and production of strong magnets the interest on Permanent Magnet Synchronous Motors (PMSM) increases continuously. With the use of PMSM it is now possible to work in a wide speed range in direct excitation systems. PMSM are widely used in different areas like elevators, electrical vehicles, pumps and space technology. In Direct Torque Control (DTC), one of the vector control methods of PMSM stator flux, rotor flux and torque are directly controlled using a suitable switching strategy for the inverter. Using DTC, a better dynamic response and a flexible control is obtained in variable speed applications in driver systems with respect to the other control methods. DTC is realized in two ways namely hysteresis and space vector modulation. In this study, the simulation of hysteresis DTC of PMSM is generated with Matlab/Simulink. According to the results obtained, it is observed that in the case that hysteresis DTC is used for the control of PMSM, a good dynamic response and flexible control can be obtained for variable load states in a wide speed range.

Dynamic Response Control of a Building Model using Bracings

Abstract Construction of tall and flexible structures has become easier now-a-days because of advances in analytical techniques and availability of more efficient materials. However, these structures are more sensitive towards dynamic loadings. Dynamic response of such structures under various excitations can be quantified by displacement and acceleration response time history. Excessive dynamic response of structure leads to substantial damage to the structural components and hence it need to be controlled. Passively, this is achieved by adding either mass or stiffness or both of them. This paper covers experimental study on controlling dynamic response of a building model using two types of bracings, namely, Concentric- and Eccentric bracing. A building model is fabricated using aluminum flats and plates and bracings are fabricated using linear springs of moderate stiffness. A model represented as Single Degree of Freedom (SDOF) system is subjected to sinusoidal excitations of various frequencies through small scale shake table. Acceleration response of a uncontrolled building model (model without bracings) is obtained using accelerometers and Data Acquisition System (DAQ) – LabVIEW 8.0. Displacement response is derived through numerical integration from acceleration response using LabVIEW. Acceleration and displacement response of controlled building model (model with bracings) are extracted and compared with uncontrolled system. Dynamic properties like Natural Time Period and Damping Ratio for both types of bracing systems are obtained and comparisons are made among them. It is found that natural time period and damping ratio of controlled building model is increased as compared to uncontrolled system due to stiffness addition. Displacement and Acceleration response are reduced appropriately for controlled system as compared to uncontrolled system.

Dynamic Response Control of Base Isolated Plane Frame Structure Using Multiple Tuned Mass Dampers

Dynamic response of a base isolated multi- storey plane frame structure with Multiple Tuned Mass Dampers (MTMD) subjected to harmonic ground excitation and Mexico earthquake excitations are studied. A four-storey plane frame structure having three degrees of freedom (two translations along x, y -axes and one rotation about z- axis) at each node, with MTMD on its base is considered for study. Comparison of response is made in terms of displacements and forces in order to investigate the effectiveness of the MTMD. The response of base isolated structure with MTMD is found to be less in comparison to the corresponding response without MTMD, implying that the MTMD is effective in reducing forces and displacements of the base isolated structure.

Study on High Dynamic Variable Speed Hydraulic Control System

A new type of high dynamic variable speed hydraulic control system is developed in this paper. In this system, a fixed displacement hydraulic pump is driven by an electrical motor which is controlled by a frequency inverter, so the discharge of the pump can be modified by changing the speed of the motor. A proportional directional valve is used to acquire higher low-speed control precision and faster dynamic response while the system is decelerating. In order to improve the dynamic response while the system is accelerating, an energy regulation device is employed in the system. The digital simulation results show that this system has higher efficiency than valve control system. Further more it has faster dynamic response and higher low-speed control precision than normal variable speed hydraulic control system.