Negative Velocity Feedback Control Research Articles

Vibration Control of Fgm Thick Shells Using Higher Order Shear Deformation Theory

Analytical solutions of Functionally Graded Material (FGM) shells with embedded magnetostrictive layers are presented in this study. These magnetostrictive layers are used for the vibration suppression of the functionally graded shells. The higher order shear deformation theory (HSDT) is employed to study the vibration suppression characteristics. The exact solution for the FGM shell with simply supported boundary conditions is based on the Navier solution procedure. Negative velocity feedback control is used. The parametric effect of the location of the magnetostrictive layers, material properties, and control parameters on the suppression effect are investigated in detail. Higher order shear deformation theory has significant influence on prediction of vibration response of thick shells. Further, it is found that (i) the shortest vibration suppression time is achieved by placing the actuating layers farthest from the neutral plane (ii) the use of thinner smart material layers leads to better vibration attenuation characteristics, and (iii) the vibration suppression time is longer for a smaller value of the feedback control coefficient.

Vibration Control of Composite Thick Shells Using Magnetostrictive Material and Higher Order Shear Deformation Theory

Analytical solutions of laminated composite shells with embedded actuating layers are presented in this study. The actuating layers are used to control natural vibration of laminated composite shell panels. The first order shear deformation theory (FSDT) and higher order shear deformation theory (HSDT) for shells are used to represent the shell kinematics and equations of motion. The exact solution for symmetric laminated shells with embedded actuating layers under simply supported boundary conditions is obtained using the Navier solution procedure. Negative velocity feedback control is used. The parametric effect of the position of the magnetostrictive layers, material properties and control parameters on the vibration suppression are investigated in detail. It is found that (i) the shortest vibration suppression time is achieved by placing the actuating layers farthest from the neutral axis (ii) using thinner smart material layers leads to better vibration attenuation characteristics and, (iii) the vibration suppression time is longer for a lower value of the feedback control coefficient. For thicker shells HSDT predicts larger amplitude of vibration and longer vibration suppression time as compared to FSDT predictions.

Effect of negative velocity feedback control on the vibration of a nonlinear dynamical system

Effect of negative velocity feedback control on the vibration of a nonlinear dynamical system

Vibration Control of a Dynamic Structure Using PLZT Sensor and Actuator with Temperature Variation

Piezoelectric material PLZT exhibits non-linearity in the dielectric constant and piezoelectric strain coefficient with respect to the temperature. In this paper, the active vibration control technique is employed on a cantilevered plate structure using PLZT piezoelectric material as a sensor as well as an actuator. The variation in dielectric constant and piezoelectric strain coefficient with change in temperature is considered while actively controlling the vibrations of the plate instrumented with PLZT patches. The finite element modeling of the structure is done using Hamilton’s principle. The modified constitutive equations of piezoelectric material PLZT are included for dielectric constant and piezoelectric strain coefficient with respect to the temperature variation. The vibrations are sensed by one piezoelectric patch at different ambient temperatures ranging from 27 °C to −15 °C. The negative velocity feedback control law is used for the active vibration control of the structure. The second piezoelectric patch is used as an actuator in the same temperature range of 27 °C to −15 °C. The experiments are performed for two cases: in case 1 the effect of temperature on dielectric constant and piezoelectric strain coefficient is ignored in the control law for active vibration control of the structure. In case 2 the effect of temperature on dielectric constant and piezoelectric strain coefficient is considered in the control law. In this work, the active vibration control of a dynamic structure is achieved by using PLZT piezoelectric material with the variation in ambient temperature.

Effect of porosity on active vibration control of smart structure using porous functionally graded piezoelectric material

The present work investigates the active vibration control of host structure bonded with functionally graded piezoelectric material (FGPM) as sensor and actuator layer. The effect of porosity volume fraction (ψ) and volume fraction index (λ) on active vibration attenuation is investigated and compared with the dense FGPM sensor and actuator layer. For more real life applications of FGPMs, two piezoelectric materials (PZT-5H and PZT-4) are modelled smoothly in a particular direction. The mechanical and piezoelectric properties of FGPMs vary across the thickness and calculated using power – law expressions. In addition to dense FGPM, two different distributions of the porosities are investigated. Shear deformation theory of first order is used to simulate the vibration response of the host composite plate based on Hamilton’s principle. A well-established negative velocity feedback controller is deployed to obtain active vibration control of the composite structure. The numerical results reveal that the volume fraction index (λ) plays vital role in the active damping of structural vibration. The FGPM-◊ demonstrates 5.7% and 6.32% improved active vibration damping performance compared to FGPM-UD at ψ = 0.1 and ψ = 0.2 respectively. The present investigation can be utilized for further studies on active vibration control of host structures integrated with FGPMs.

Active vibration suppression of wind turbine blades integrated with piezoelectric sensors

Abstract As the wind turbine size gets larger, the optimal design of blades, which is a major source of energy for the wind turbines and also the cause of loads, is becoming more important than anything else. Therefore, reducing the load on the blade should be the top priority in designing a blade. In this article, we studied the vibration control of the stiffened wind blades subjected to a wind load with piezoelectric sensors and actuators to mitigate fluctuations in loading and adding damping to the blade. The model is a laminated composite blade with a shear web and the PZT piezomaterial layers embedded on the top and bottom surfaces act as a sensor and actuator, respectively. A uniformly distributed external wind load is assumed over the entire plate surface for simplicity. The first-order shear deformation (FSDT) theory is adopted, and Hamilton’s principle is used to derive the finite element equation of motion. The modal superposition technique and the Newmark- β \beta method are used in numerical analysis to calculate the dynamic response. Using the constant gain negative velocity feedback control algorithm, vibration characteristics and transient responses are compared. Furthermore, vibration control at various locations of the shear webs subjected to an external load is discussed in detail. Through various calculation results performed in this study, this article proposes a method of designing a blade that can reduce the load by actively responding to the external load acting on the wind turbine blade.

Vibration Control for a Coupled Pitch- roll Ship Model Via a Negative Cubic Velocity Feedback Control

One of the most essential ship reactions to waves is roll motion. Due to the intricacy of ship wave interactions and their sensitivity, predicting such a reaction is extremely challenging. Because vibration motion is an undesirable occurrence, it must be removed, decreased, or controlled. A coupled Pitch- roll ship model with negative cubic velocity feedback control subjected to parametric excitations is premeditated and solved in this paper. The method of multiple time scales is applied to scrutinize the response of the two modes of the system neighbouring the simultaneous sub-harmonic, and internal resonance situation. Besides, the steady-state solution is determined through the Rung-Kutta Method (RKM) of fourth order. Stability of the steady state solution near this resonance case is discussed and studied applying Lyapunov’s first indirect method and Routh- Hurwitz criterion. The influences of the different parameters on the steady state solution are reconnoitred and discussed. The controller effects on the stability are clarified. Simulation results are accomplished with the help of MATLAB and Maple software programs.

Effect of the Negative Velocity Feedback Control for Reducing the Primary Resonance Vibration of a Magnetic Levitation System using the Harmonic Balance Method

Effect of the Negative Velocity Feedback Control for Reducing the Primary Resonance Vibration of a Magnetic Levitation System using the Harmonic Balance Method

Duffing Oscillator’s Vibration Control under Resonance with a Negative Velocity Feedback Control and Time Delay

An externally excited Duffing oscillator under feedback control is discussed and analyzed under the worst resonance case. Multiple time scales method is applied for this system to find analytic solution with the existence and nonexistence of the time delay on control loop. An appropriate stability analysis is also performed and appropriate choices for the feedback gains and the time delay are found in order to reduce the amplitude peak. Different response curves are involved to show and compare controller effects. In addition, analytic solutions are compared with numerical approximation solutions using Rung-Kutta method of fourth order.

Optimal distribution of active piezoelectric elements for noise attenuation in sandwich panels

ABSTRACT In this paper, a multiobjective optimization approach for obtaining the optimal distribution of surface-bonded piezoelectric sensors and actuators for noise attenuation in sandwich panels is presented. The noise attenuation is achieved by using negative velocity feedback control with co-located sensors and actuators. The control gains are also optimized in order to obtain the most efficient noise attenuation in a given frequency band. An in-house implementation of a viscoelastic soft core sandwich plate finite element, including surface-bonded piezoelectric sensors and actuators with active control capabilities, is used for obtaining the frequency response of the panels. The sound transmission capability of the panels is evaluated using the radiated sound power, along with the Rayleigh integral approach, which is suitable for lightly coupled structural/acoustic problems. The Direct MultiSearch (DMS) optimization algorithm is used to minimize the added weight due to the piezoelectric material, minimizing also the number of required controllers and maximizing the noise attenuation. The total length of the radiated sound power curve is shown to be an effective measure of noise attenuation in a given frequency band. Trade-off Pareto fronts and the obtained optimal configurations are presented and discussed.

Temperature Variation Effect on the Active Vibration Control of Smart Composite Beam

Abstract Due to their impressive capacity of sensing and actuating, piezoelectric materials have been widely merged in different industrial fields, especially aeronautic and aerospace area. However, in the aeronautic industry, the structures are operating under critical environmental loads such as high and very low temperature, which made the investigation of the effect of thermal forces on the piezoelectric structures indispensable to reach the high functionality and performance. The present paper focuses on the effect of thermal loads on the active vibration control (AVC) of structures like beams. For this purpose, a finite element model of composite beam with fully covered piezoelectric sensor and actuator based on the well-known high order shear deformation theory is proposed by taking into account the electrical potential field and a linear temperature field. Hamilton’s principle is used to formulate the electro-thermo-mechanical governing equations. The negative velocity feedback controller is implemented to provide the necessary gain for the actuator. Different analyses are effectuated to present the effect of the temperature ranging from -70°C to 70°C on the active vibration control of the composite beam.

Multiobjective optimization solutions for noise reduction in composite sandwich panels using active control

In this paper, optimal solutions for noise reduction in laminated viscoelastic soft core sandwich plates are obtained, using active control with surface bonded piezoelectric sensors and actuators. An in–house finite element implementation of the active laminated sandwich plate is used to obtain the frequency response of the panels. Since the structural/acoustic problem is lightly coupled, the sound transmission characteristics of the panels are evaluated by computing their radiated sound power, using the Rayleigh integral method. A negative velocity feedback control law has been used to implement the active damping. The optimal location of the surface co-located pairs of piezoelectric patches is then obtained, using the Direct MultiSearch (DMS) optimization algorithm to minimize simultaneously the added weight, the number of controllers and noise radiation. The minimization of noise radiation is accomplished by minimizing the total length of the radiated sound power frequency response curve. Trade-off Pareto fronts and the respective optimal active patch configurations are obtained and discussed.

Optimal locations of discontinuous piezoelectric laminated cylindrical shell with point supported elastic boundary conditions for vibration control

In this paper, the vibration control of discontinuous piezoelectric laminated shell with point supported elastic boundary conditions are investigated, and the location of piezoelectric layer are optimized. The point supported boundary condition are simulated by using artificial springs. The position with the piezoelectric layer are considered to be a laminated shell, and the position without the piezoelectric layer are regarded as a thin-walled cylindrical shell. The strain and curvature expressions of the cylindrical shell are obtained by the first-order shear shell theory, and the Chebyshev polynomial is used as the admissible displacement functions. Then, the differential equation of coupling motion of piezoelectric laminated cylindrical shells is established by using Lagrange equation, and the negative velocity feedback control is used as the control strategy. The Newmark method is used to obtain the response curves. The accuracy of the model are verified by comparing with the ANSYS results. For better vibration control, the optimal locations of the piezoelectric layer are obtained by using the Multi-Objective Particle Swarm Optimization algorithm based on the crowding distance. Finally, the optimization results and the vibration control of the piezoelectric layer are verified by analyzing the radial displacement response of the cylindrical shell.

Active control of adaptive thin-walled beams incorporating bending-extension elastic coupling via piezoelectrically induced transverse shear

Abstract Problems related to mathematical modeling and active control of adaptive composite thin-walled beams incorporating lateral bending-extension elastic coupling and piezoelectrically induced transverse shear-extension actuation coupling are considered. The adaptive capabilities are provided by anisotropic piezo-actuators embedded into the host structure. Based on classical negative velocity feedback control and linear-quadratic regulator optimal control, the control authority played by the directionality property of piezo-actuators on vibration suppression is discussed, considering in conjunction with that of the structural tailoring. The results show that the control strategy based on the piezoelectrically induced transverse shear-extension coupling can be more efficient than that based on the piezoelectrically induced bending. In addition, the control effectiveness based on the piezoelectrically induced transverse shear is sensitive to the bending-extension elastic coupling.

Multidimensional Vibration Suppression Method with Piezoelectric Control for Wind Tunnel Models.

In wind tunnel tests, the low-frequency and large-amplitude vibration of the cantilever sting result in poor test data in pitch plane and yaw plane, more seriously, even threatens the safety of wind tunnel tests. To ensure the test data quality, a multidimensional vibration suppression method is proposed to withstand the vibration from any direction, which is based on a system with stackable piezoelectric actuators and velocity feedback employing accelerometers. Firstly, the motion equation of the cantilever sting system is obtained by Hamilton’s principle with the assumed mode method. Then, the multidimensional active control mechanism is qualitatively analyzed and a negative velocity feedback control algorithm combined with a root mean square (RMS) evaluation method is introduced to realize active mass and active damping effect, meanwhile, a weight modification method is performed to determine the sequence number of the stacked piezoelectric actuators and the weight of control voltages in real time. Finally, a multidimensional vibration suppression system was established and verification experiments were carried out in lab and a transonic wind tunnel. The results of lab experiments indicate that the damping ratio of the system is improved more than 4.3 times and the spectrum analyses show reductions of more than 23 dB. In addition, wind tunnel test results have shown that for the working conditions (α = −4~10° with γ = 0° or α = −4~10° with γ = 45°) respectively at 0.6 Ma and 0.7 Ma, the remainder vibration is less than 1.53 g, which proves that the multidimensional vibration suppression method has the ability to resist vibration from any direction to ensure the smooth process of wind tunnel tests.

Temperature-Robust Active Vibration Controller Using MWCNT/Epoxy Strain Sensor and PZT-5H Actuator

Active vibration control (AVC) of a cantilevered beam using a multiwalled carbon nanotube (MWCNT)/epoxy nanocomposite strain sensor and piezoelectric actuator at elevated temperature has been performed. The resistance of the nanocomposite strain sensor varies nonlinearly with the change in temperature. To use a carbon nanotube (CNT) nanocomposite strain sensor in AVC applications, the temperature variation of the sensor must be taken into account. A control law for AVC of the first mode of vibration of the cantilevered beam was derived using a negative velocity feedback control law. AVC of the first mode of the smart cantilevered beam instrumented with a collocated CNT nanocomposite strain sensor and piezoelectric actuator was performed at temperatures in the range of 40°C to 60°C under two cases, viz. without and with consideration of the temperature dependence of the CNT strain sensor in the control law, revealing that AVC performance was only maintained at elevated temperature in the latter case. These results suggest a strategy for AVC of a structure using a MWCNT/epoxy strain sensor and PZT-5H actuator that is robust to variations in temperature.

Multiwalled Carbon Nanotube Film Composite for Active Vibration Control of Cantilevered Beam

A novel scheme for active vibration control using MWCNT/epoxy strain sensor is analytically derived and experimentally verified. Mathematical model of smart cantilevered beam instrumented with collocated CNT strain sensor and PZT-5H actuator is derived. Fabrication process of CNT strain sensor and instrumentation of signal-conditioning unit is also detailed. Active vibration control (AVC) of the first mode of vibration of smart cantilevered beam instrumented with CNT stain sensor and PZT-5H actuator is conducted experimentally at ambient temperature. It is observed from experiments that the AVC scheme is realized by using negative first modal velocity feedback control law.

Modeling and control for rotating pretwisted thin-walled beams with piezo-composite

In this paper, a rotating thin-walled beam theory incorporating fiber-reinforced and piezo-composite is developed and used to study the active control for vibration suppression. The structural model accounts for transverse shear strain, primary and secondary warpings, pretwist and presetting angles. In addition, the centrifugal stiffening effect, tennis-racket effect, flapping-lagging-transverse shear and extension-twist couplings are accounted as well. Based on a negative velocity feedback control algorithm, the effective damping performance is optimized by studying anisotropic characteristics of piezo-actuators and elastic tailoring of the host structure. Moreover, relations between damping control authority and design factors, such as rotor speed, presetting and pretwist angles are investigated in detailed.

Velocity feedback damping of piezo-actuated wings

A geometrical nonlinear model of thin-walled beams with fiber-reinforced and piezo-composite is developed for smart aircraft wing structures. Some non-classical effects such as warping inhibition and three-dimensional (3-D) strain are accounted for in the beam model. The governing equations and the corresponding boundary conditions are derived using the Hamilton’s principle. The Extended Galerkin’s Method is used for the numerical study. A negative velocity feedback control algorithm is adopted to control the aircraft wing response. The effective damping performance is optimized by studying anisotropic characteristics of piezo-composite and elastic tailoring of the fiber-reinforced host structure. The relations between active vibration control effect and design factors, such as the size and position of piezo-actuator are investigated in detailed.

AVC of a smart plate with PZT sensor-actuator using direct method of model updating

ABSTRACTThis paper presents a novel technique for Active Vibration Control (AVC) based on updated mathematical model of a mechanical structure. Vibrations of a smart plate instrumented with PZT sensor and actuator are suppressed using a negative velocity feedback controller. The AVC controllers are designed and compared for two cases. In first case it is assumed that there is a mismatch between the analytical model and the actual structure. In the second case the mismatch in analytical model and actual structure is compensated using direct method of model updating. Numerical simulations carried out in MATLAB software for these two cases demonstrate the improvement in performance of the AVC controller when updation is carried out.