scholarly journals Active Actuating of a Simply Supported Beam with the Flexoelectric Effect

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1735
Author(s):  
Mu Fan ◽  
Hequn Min
Keyword(s):  
Coupling Effect ◽  
Rank Order ◽  
Transverse Displacement ◽  
Control Force ◽  
Engineering Structures ◽  
Simply Supported Beam ◽  
Mechanical Coupling ◽  
Simply Supported ◽  
Flexoelectric Effect ◽  
Probe Location

Piezoelectric materials with the electro-mechanical coupling effect have been widely utilized in sensors, dampers, actuators, and so on. Engineering structures with piezoelectric actuators and sensors have provided great improvement in terms of vibration and noise reduction. The flexoelectric effect—which describes the coupling effect between the polarization gradient and strain, and between the strain gradient and electric polarization in solids—has a fourth-rank order tensor electro-mechanical coupling coefficient, and in principle makes the flexoelectricity existing in all insulating materials and promises an even wider application potential in vibration and noise control. In the presented work, a flexoelectric actuator was designed to actuate a simply supported beam. The electric field gradient was generated by an atomic force microscopy probe. Flexoelectric control force and moment components could be induced within the flexoelectric control layer. As flexoelectricity is size-dependent, the key parameters that could affect the actuating effect were examined in case studies. Analytical results showed that the induced flexoelectric control moment was strongly concentrated at the probe location. The controllable transverse displacement of the simply supported beam was calculated with the modal expansion method. It was found that the controllable transverse displacement was dependent on the probe location as well.

Feed-Forward Control of a Cracked Simply Supported Beam

2011 ◽  
Author(s):  
Sudhir Kaul
Keyword(s):  
Crack Propagation ◽  
Control Algorithm ◽  
Control Algorithms ◽  
Transverse Displacement ◽  
Control Force ◽  
Simply Supported Beam ◽  
Feed Forward ◽  
Simply Supported ◽  
Crack Location ◽  
Feed Forward Control

This paper demonstrates the use of two feed-forward control algorithms in order to mitigate crack propagation in a simply supported beam with a pre-existing crack. The main objective of the control algorithms is to minimize or reduce transverse deflection at the crack location so as to contain the damage resulting from the pre-existing crack and, thereby, reduce the rate of crack propagation. A point-load sinusoidal excitation, from a known disturbance, is used as the input load acting on the beam. Two control algorithms are used — the first control algorithm computes a control force to eliminate transverse displacement at the crack location resulting from the excitation force, and the second control algorithm minimizes the mean square transverse displacement over a section of the beam that contains the crack. Both the control algorithms are a-causal and assume that the excitation input is completely known a-priori. Simulation results for a simply supported beam are presented and discussed in detail. It is observed that the rate of crack propagation can be significantly reduced by implementing the proposed feed-forward control algorithms, increasing the useful life of the damaged beam. Also, it is found that the transverse displacement over a significant length of the beam can be substantially reduced when the beam response is dominated by a specific mode.

scholarly journals Peridynamic Higher-Order Beam Formulation

2020 ◽  
Author(s):  
Zhenghao Yang ◽  
Erkan Oterkus ◽  
Selda Oterkus
Keyword(s):  
Finite Element Method ◽  
Cantilever Beam ◽  
Higher Order ◽  
Point Load ◽  
Transverse Displacement ◽  
Lagrange Equations ◽  
Concentrated Load ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Good Agreement

Abstract In this study, a novel higher-order peridynamic beam formulation is presented. The formulation is obtained by using Euler-Lagrange equations and Taylor’s expansion. To demonstrate the capability of the presented approach, several different beam configurations are considered including simply supported beam subjected to distributed loading, simply supported beam with concentrated load, clamped-clamped beam subjected to distributed loading, cantilever beam subjected to a point load at its free end and cantilever beam subjected to a moment at its free end. Transverse displacement results along the beam obtained from peridynamics and finite element method are compared with each other and very good agreement is obtained between the two approaches.

Flexoelectric Vibration Control of Plates by Line Electrodes

2016 ◽  
Author(s):  
X. F. Zhang ◽  
H. Y. Li ◽  
H. S. Tzou
Keyword(s):  
Electric Field ◽  
Vibration Control ◽  
Bottom Surface ◽  
Modal Control ◽  
Sensors And Actuators ◽  
Structural Dynamic ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Flexoelectric Effect ◽  
Conductive Line

The electric polarization induced by the strain gradient is the direct flexoelectric effect; the mechanical stress/strain induced by the electric field gradient is the converse flexoelectric effect. Accordingly, flexoelectric sensors and actuators are respectively designed to monitor the structural dynamic behavior and to control the structural vibration. In this study, a line-electrode induced flexoelectric actuation is designed to control the plate vibrations. A flexoelectric layer laminated on the thin plate is used as a distributed actuator. The bottom surface of the flexoelectric actuator is a common electrode and the top surface is driven by a conductive line to generate an inhomogeneous electric field. Based on the converse flexoelectric effect, the electric filed gradient induces mechanical stresses in the flexoelectric layer resulting in induced bending moments to the plate structure. With the control moment imposed on the plate, flexoelectric vibration control of the plate is evaluated in this study. The objective of this study is to explore the modal control effects of the plate by the conductive line excitation. For a plate with two opposite sides simply supported and the other two are free (SS-F-SS-F), vibration control response of the plate is studied when the conductive line locates parallel to the y width direction. Then, independent modal control effects (i.e., the induced or controllable displacements by the flexoelectric actuator) are evaluated for the modes (1,1), (1,2), (1,3), (2,1) and (3,1) with different line actuation locations. Control effects of the conductive line location to various plate modes are explored and results show that the optimal conductive line location differs for different plate modes. When the FF width decreases to far less than the SS length, the SS-F-SS-F plate is degraded to a simply supported beam. Then, control effects for modes (1,1), (2,1) and (3,1) with different conductive line locations are discussed. The results are compared with the control effect derived directly by the simply supported beam theory. Thus, this study suggests that plate vibration can be controlled by the line-electrode induced converse flexoelectric effect. Conductive line locations are critical to control of various plate modes.

scholarly journals Research on the Dynamic Responses of Simply Supported Horizontal Pipes Conveying Gas-Liquid Two-Phase Slug Flow

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 83
Author(s):  
Gang Liu ◽  
Zongrui Hao ◽  
Yueshe Wang ◽  
Wanlong Ren
Keyword(s):  
Slug Flow ◽  
Peak Frequency ◽  
Dynamic Responses ◽  
Piping System ◽  
Transverse Displacement ◽  
Vibration Acceleration ◽  
Two Phase ◽  
Horizontal Pipes ◽  
Simply Supported ◽  
Superficial Gas Velocity

The dynamic responses of simply supported horizontal pipes conveying gas-liquid two-phase slug flow are explored. The intermittent characteristics of slug flow parameters are mainly considered to analyze the dynamic model of the piping system. The results show that the variations of the midpoint transverse displacement could vary from periodic-like motion to a kind of motion whose amplitude increases as time goes on if increasing the superficial gas velocity. Meanwhile, the dynamic responses have certain relations with the vibration acceleration. By analyzing the parameters in the power spectrum densities of vibration acceleration such as the number of predominant frequencies and the amplitude of each peak frequency, the dynamic behaviors of the piping system like periodicity could be calculated expediently.

Analysis of the Electro-Mechanical Responses of the Piezoelectric Motor Based on Finite Element Method

2014 ◽  
Vol 697 ◽  
pp. 181-186
Author(s):  
Zi Lei Wang ◽  
Tian De Qiu
Keyword(s):  
Finite Element ◽  
Coupling Effect ◽  
Complex Stress ◽  
Piezoelectric Resonator ◽  
Element Analysis ◽  
Mechanical Coupling ◽  
Mechanical Responses ◽  
Stress Boundary Condition ◽  
Piezoelectric Field ◽  
Stress Boundary

The piezoelectric field and structure field of piezoelectric resonator of ultrasonic motor are intercoupling. It is difficult to obtain the solution under some circumstances because of the complex stress boundary condition and the influence of coupling effect. An electro-mechanical coupling finite-element dynamic equation is established on the basis of the Hamilton’s Principle about piezoceramic and elastomer. The equation is decoupled through the shock excitation of the piezoelectric resonator and the piezoelectricity element and material provided by finite-element analysis. As a result, an admittance curve as well as the distribution status of the nodal DOF is obtained, which provides an effective method to solve electro-mechanical coupling problems.

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