Smart Beam Research Articles

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.

A balanced laminate of piezoelectric fiber composite for improved shear piezoelectric actuation of beams

A new balanced laminate of piezoelectric fiber composite (PFC) is presented for the improved shear mode piezoelectric actuation of beams. A micromechanics formulation is first presented for determination of its effective electromechanical properties, and then its shear actuation capability is investigated by means of utilizing it for actuation of bending deformation of a smart sandwich beam. The results reveal an indicatively higher shear actuation capability of the present balanced laminate of PFC over that of the monolithic shear piezoelectric actuators, and thus this laminate of PFC may be a potential material for shear piezoelectric actuators in control of flexible structures.

Gust load alleviation in a flexible smart idealized wing

Among the aeroelastic phenomena most commonly affecting flexible and very flexible aircraft, those caused by gusts deserve special attention due to their potential either in degrading flying qualities and ride comfort or in increasing structural loads. It is then of interest to structural loads and flight controls engineers that solutions be developed to attenuate the effects of gusts on aircraft. Particularly, the use of piezoelectric transducers arises as one of the potential solutions in the design of gust load alleviation and structural mode suppression systems. In this paper, the gust load alleviation on a flexible smart idealized wing using only piezoelectric transducers is analyzed and experimentally tested. The numerical model includes a finite-element model of the wing, employing two-node, seven-degree-of-freedom smart beam elements, assuming small deformations and neglecting transverse shear. A quasi-steady, strip-theory-based aerodynamic model is used. Two control laws are evaluated: one based on output feedback, and the other based on feedback of observed states of a truncated system. Using a gust generator, wind-tunnel tests were performed at different flow speeds and gust frequencies to validate the computational model and to verify the performance of piezoelectric transducers. The results show a considerable attenuation of the wing root bending moment, especially using two piezoelectric actuators. Important performance improvements were overall verified with feedback of observed states when compared with static output feedback, specially to decrease the participation of the elastic modes in the gust response.

A Switched Beamforming Network for 5G Modern Wireless Communications Applications.

Abstract This work presents compact design of a smart beam steerable array antenna based on branch-line hybrid coupler by using meander-line and open stubs technique to achieve a good performance and miniature structure at 26GHz frequency band for 5G wireless communication applications. The proposed hybrid coupler achieved an impedance bandwidth over 46% with coupling coefficient -3.48dB, isolation coefficient of below -25dB and reflection coefficient of below -24dB. The result shows a good performance. To implement the new hybrid coupler. The proposed series-fed array antenna can produce radiation patterns that can be changed to different beam for reduce the existing interference. The designed array has ten elements series antenna and is fed by a branch-line hybrid coupler, which serves as a beam-former to obtain the beam scanning ranging from -32 to +32 degrees. The simulation results show the return loss of the switched beam antenna can be achieved below -18dB over a 20% bandwidth with a center frequency at 26GHz The maximum gain of 12.398dB and a wideband that cover from 23.34GHz to 28.25GHz was obtained by simulation using Keysight ADS software. All simulated results are clearly presented.

Disturbance rejection control with H∞ optimized observer for vibration suppression of piezoelectric smart structures

In this paper, a disturbance rejection (DR) control with H∞ optimized observer is developed for vibration suppression of smart structures considering model uncertainties and measurement noise. An electro-mechanically coupled dynamic finite element (FE) model of piezoelectric smart structures is firstly built for control design. Based on the dynamic FE model, the H∞ optimized observer is designed with a dynamic feedback gain which is calculated by H∞ mixed sensitivity optimization. Expected response speed and robustness to model uncertainties and measurement noise are obtained by configuring proper weighting functions. In the closed-loop system, estimated disturbances and state variables are fed back through a conventional DR controller to counteract disturbances and stabilize the system. In order to validate the DR control with H∞ optimized observer, vibration suppression simulations of a piezoelectric smart beam are implemented in the absence and presence of model uncertainties and measurement noise, respectively. Furthermore, DR control with generalized proportional integral observer and DR control with high-gain proportional integral observer are added for comparison. Results show that excellent vibration suppression performance and better robustness to model uncertainties and measurement noise are achieved by the DR control with H∞ optimized observer.

Active control of micro Reddy beam integrated with functionally graded nanocomposite sensor and actuator based on linear quadratic regulator method

In this paper, optimal active vibration control of a micro sandwich beam is studied. Face sheets are made from piezoelectric materials and reinforced by functionally graded distributions of carbon nanotubes. Also bottom and top face sheets operate as distributed sensor and actuator, respectively. Based on modified strain gradient theory and Hamilton's principle, the governing equations of motion for presented smart micro Reddy beam are derived and optimal active vibration control is applied using state-space form of equations of motion and linear quadratic regulator algorithm. The results show that considering MSGT, the amplitude of the center point deflection and settling time decrease. Also CNTs distributions effect on stability and active vibration control of the smart structure and LQR algorithm is essentially an automated way of finding an appropriate state-feedback controller. This study is a theoretical background for more research and further experimental investigation, in the field of micro smart structures.

Comprehensive Analysis of Smart Beams

This paper introduces a comprehensive analysis tool and framework for studying the structural dynamic and aeroelastic behavior of smart beams. It includes the theory behind the components of this comprehensive analysis tool and a verification of the proposed framework. This tool is used to study the aeroelastic behavior of a smart beam. This analysis is followed by a failure analysis in order to ensure the integrity of the structure under operation. This comprehensive analysis tool couples the variational asymptotic beam sections, geometrically exact fully intrinsic beam equations, and the circuit equation for smart materials. It takes into account the electromechanical coupling behavior of smart materials both in the cross-sectional analysis and in the one-dimensional generalized beam theory.

Active Vibration Control of Cantilever Beam by Using Optimal LQR Controller

Many of mechanical systems are exposed to undesired vibrations, so designing an active vibration control (AVC) system is important in engineering decisions to reduce this vibration. Smart structure technology is used for vibration reduction. Therefore, the cantilever beam is embedded by a piezoelectric (PZT) as an actuator. The optimal LQR controller is designed that reduce the vibration of the smart beam by using a PZT element. 
 In this study the main part is to change the length of the aluminum cantilever beam, so keep the control gains, the excitation, the actuation voltage, and mechanical properties of the aluminum beam for each length of the smart cantilever beam and observe the behavior and effect of changing the length of the smart cantilever beam. A cantilever beam with piezoelectric is modeled in Mechanical APDL ANSYS version 15.0 and verified this by using experimental work. The AVC was tested on a smart beam under different control gains in experimental work and chose the best control gain depending on FEM results for each length of the smart beam. The response of the smart beam is noticed to be different for every length and the reduction percentage for settling time was different for every length.

Adaptive vibration control for a cantilevered beam using actuating and sensing functions of a piezoelectric bimorph

The paper investigates that the free vibration for a smart cantilevered beam utilizing actuating and sensing properties of a piezoelectric bimorph is suppressed by a adaptive controller. Through the bimorph, the suppression vibration of a flexible cantilevered beam is studied. Because of uncertain parameters in the dynamic model, a adaptive control is adopted with a minimum variance self-tuning direct regulator to control the free vibration of the smart beam. By some simulation and experiment verifications, the adaptive control is proved to be feasible for attenuating the free vibration of the smart beam.

MWCNT/epoxy strip-like sensors for buckling detection in beam-like structures

Buckling of slender structures constitutes a hazardous failure mechanism that can yield partial or total collapses. Nonetheless, given that buckling failure is characterized by a highly non-linear and sudden loss of stability, most off-the-shelf monitoring systems fail to detect buckling and very few research works in the literature can be found in this regard. Recent advances in the field of Nanotechnology have fostered the development of innovative composite materials with multifunctional properties, offering vast possibilities in the field of Structural Health Monitoring. Along these lines, the present work proposes a novel concept of smart beams for buckling detection applications. This consists of the deployment of carbon nanotube-reinforced epoxy strip-like sensors on the upper and bottom faces of a beam-like structure. Carbon nanotube-reinforced composites exhibit strain self-sensing capabilities, that is to say, these composites provide measurable variations in their electrical properties under the action of mechanical strains. In this way, the proposed sensing strips not only act as mechanical reinforcements, but also confer self-diagnostic properties to the system. The failure detection principle of the proposed smart beams consists of the assessment of the bending-induced variations of the normal strains during buckling. To do so, the electrical resistance of the sensing strips is continuously monitored through a two-probe resistivity measurement scheme. The present research furnishes detailed numerical parametric analyses to investigate the effectiveness of the proposed smart beams to detect buckling under uniaxially compression, as well as to evaluate the influence of design parameters such as filler volume fraction, boundary conditions and electrodes layouts. The macroscopic behaviour of the smart beams is simulated by a micromechanics-based piezoresistivity model and a multiphysics finite element code. The numerical results demonstrate that the buckling failure can be tracked through sudden disturbances in the electrical output of the smart strips.

First two modal adaptive vibration control for a smart beam with two piezoelectric bimorphs by a self-tuning PID control

This paper presents model and simulation verification of vibration suppression to two-input two-output system of a smart cantilever beam bonded with piezoelectric bimorphs by Self-tuning PID controller. The Self-tuning PID controller is designed for the smart cantilever beam with pole-placement method theory and recursive algorithm. The displacement is acquired by the Piezoelectric bimorph on the root of the smart cantilever beam. The control voltage is calculated by the designed Self-tuning PID control parameters. The established model realizes simulation through Simulink of MATLAB. Through some simulation verification results, it is indicated that the suppressed amplitude of free vibration is obvious. Therefore, it is demonstrated that the Self-tuning PID control for two-input two-output smart beam system with Piezoelectric bimorphs is feasible to reduce free vibration.

Dynamic buckling of smart sandwich beam subjected to electric field based on hyperbolic piezoelasticity theory

In this paper, dynamic buckling of the smart subjected to blast load subjected to electric field is studied. The sandwich structure is rested on Pasternak foundation with springs and shear elements. Applying piezoelasticity theory and hyperbolic shear deformation beam theory (HSDBT), the motion equations are derived by energy method. For calculating the dynamic instability region (DIR) of the sandwich structure, differential quadrature method (DQM) along with Bolotin method is used. The aim of this study is to investigate the effects of applied voltage, geometrical parameters of structure and boundary conditions on the DIR of the structure. The results show that applying negative voltage, the DIR will be happened at higher excitation frequencies. In addition, the clamped-clamped beam leads to higher excitation frequency with respect to simply supported boundary condition.

Different fractional order models for an experimental smart beam system

Different fractional order models for an experimental smart beam system

Active vibration control of smart beam under parametric variations

Vibration control is one of the prominent factors, especially in lightweight structures in space technology. These structures, due to their low mass and thinness, frequently lose the stability under environmental disturbances. Piezoelectric materials as sensors/actuators have been widely used to control vibrations and mode shapes of such structures. Nowadays, piezoelectric and passive materials like viscoelastic materials have shown combined advantage of hybrid damping (active constrained layer damping) and with different parametric variations in them have shown remarkable property for control authority. This paper presents the details of parametric variations in smart structure using energy methods to demonstrate the utility for further structure design. Finite element model has been implemented using MATLAB software to analyze its effect of various parameters. Different environmental temperatures as thermal loads have been considered, and their effect on damping ratio is investigated. Parameters like percentage coverage of viscoelastic, piezoelectric material patches and the shape of patches on damping characteristics have been demonstrated.

Dynamic Simulation of a Metamaterial Beam Consisting of Tunable Shape Memory Material Absorbers

Metamaterials are materials with an artificially tailored internal structure and unusual physical and mechanical properties such as a negative refraction coefficient, negative mass inertia, and negative modulus of elasticity, etc. Due to their unique characteristics, metamaterials possess great potential in engineering applications. This study aims to develop new acoustic metamaterials for applications in semi-active vibration isolation. For the proposed state-of-the-art structural configurations in metamaterials, the geometry and mass distribution of the crafted internal structure is employed to induce the local resonance inside the material. Therefore, a stopband in the dispersion curve can be created because of the energy gap. For conventional metamaterials, the stopband is fixed and unable to be adjusted in real-time once the design is completed. Although the metamaterial with distributed resonance characteristics has been proposed in the literature to extend its working stopband, the efficacy is usually compromised. In order to increase its adaptability to time-varying disturbance, several semi-active metamaterials have been proposed. In this study, the incorporation of a tunable shape memory alloy (SMA) into the configuration of metamaterial is proposed. The repeated resonance unit consisting of SMA beams is designed and its theoretical formulation for determining the dynamic characteristics is established. For more general application, the finite element model of this smart metamaterial is also derived and simulated. The stopband of this metamaterial beam with different configurations in the arrangement of the SMA absorbers was investigated. The result shows that the proposed model is able to predict the unique dynamic characteristics of this smart metamaterial beam. Moreover, the tunable stopband of the metamaterial beam with controlling the state of SMA absorbers was also demonstrated.

Active, artificial hair cells for biomimetic sound detection based on active cantilever technology.

We aim at building and studying artificial hair cells (AHC) based on MEMS technology to understand the extraordinary sound perception of the human ear and build a sensor system with similar properties. These perception properties, i.e. detecting six orders of sound pressure level and simultaneously frequency differences of only 3-5 Hz, are obtained mainly due to the sophisticated biological sensors in the inner ear, called hair cells, which convert the acoustic waves into electric signals. They amplify weak inputs and compress larger ones, known as compressive nonlinearity, thus enabling this impressive dynamic range, typically not captured by current engineering solutions. We tackle this demand by building artificial hair cells on the basis of smart, self-actuated and self-sensing mechanical resonator beams with suitable actuation feedback. Thereby, we take advantage of the fact that the compressive nonlinearity arises naturally in dynamical systems tuned to a bifurcation point. This tuning is achieved by an appropriate feedback loop inspired by physiological models. Initial results on the detection properties of a single AHC will be shown demonstrating amplification and a decreased width of the resonance peak.

A new nonlinearly tapered FGM piezoelectric energy harvester

This work presents an analytical model for the development of a piezoelectric energy harvester with general nonlinear geometry and functionally graded material (FGM) properties based on Adomian decomposition method. The model is applied to geometrically and materially non-uniform beams with structural strain rate damping and surface bonded piezoelectric layers to derive the dynamic response of the smart structure to base motion excitations and efficiently harvesting the subsequent vibrational energy. Firstly, the steady state vibration response of the smart non-uniform FGM beam subjected to a harmonic base motion is obtained and then electromechanical outputs of the piezoelectric patches are analytically derived. Furthermore, a comprehensive parametric study for bimorph piezoelectric energy harvesters with different nonlinearly tapered geometry and FGM properties in a wide frequency range has been done. Considering the same volume of the harvester, it is demonstrated that the novel non-uniform FGM design can significantly increase the electrical output of the harvester by more than 19.76 times compared to the traditional uniform homogenous design. With the presented methodology, optimum structural design for piezoelectric energy harvesters with respect to the operation frequency domain can be effectively achieved.

Active vibration control of a smart beam by a tuner-based PID controller

In this study, a tuner-based Proportional-Integral-Derivative controller is proposed to actively control a smart beam. In numerical simulation environment, the performance of the tuner-based PID and a positive position feedback controller in damping the forced vibrations of a smart beam using a piezoelectric actuator are investigated. The finite element method is used to numerically model the smart beam by exporting the state-space matrices that are characterized with regard to the active vibration control loop. Two types of vibration data with sine tones are comprised in order to stimulate behavior of the proposed system. The first one is the composition of the first and second natural frequencies of smart beam. The second one is the composition of the first to the third natural frequencies of smart beam. In the tuner-based PID, controller design tuner toolbox is used to obtain suitable PID coefficients. In this simulation environment active vibration control based on the proposed tuner-based PID and on positive position feedback controllers is studied and compared. Additionally, the controller power consumption levels are determined for the proposed controller design. Numerical results show that the overall tuner-based PID control performance of flexible smart beam system is more effective than the positive position feedback controlled system for forced vibration control. Also, the tuner-based PID controller provides more energy savings than the positive position feedback controller.

Active vibration control of piezoelectric smart beams with radial basis function generated finite difference collocation method

A local collocation method based on finite difference generated radial basis functions considering supplementary polynomials is used to solve the governing equations of cantilever piezoelectric smart beams. The natural modes of vibration of a bimorph and a three-layered smart beam with an interior aluminium core are analysed for both open-circuit and closed-circuit electrical boundary conditions. Very accurate results are obtained at a low computational cost. Subsequently, a constant gain velocity feedback active vibration control system is implemented, and the time and frequency response functions of both beams subjected to initial impulse and displacement conditions are investigated. Different values of the applied gain and varying thickness of the piezoelectric layers are analysed. The governing equations are established using equivalent-single-layer first-order-shear-deformation theory with through-the-thickness quadratic layerwise electric potential for improved accuracy.