• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.269-278
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• 2003

In this study, the method of the finite element modeling for free vibration control of beam-type smart structures with bonded plate-type piezoelectric sensors and actuators is proposed. Constitutive equations for the direct piezoelectric effect and converse piezoelectric effect of piezoelectric materials are considered. By using the variational principle, the equations of motion for the smart beam finite element are derived, The proposed 2-node beam finite element is an isoparametric element based on Timoshenko beam theory. Therefore, by analyzing beam-type smart structures with smart beam finite elements, it is possible to simulate the control of the structural behavior by applying voltages to piezoelectric actuators and monitoring of the structural behavior by sensing voltages of piezoelectric sensors. By using the smart beam finite element and constant-gain feed back control scheme, the formulation of the free vibration control for the beam structures with bonded plate-type piezoelectric sensors and actuators is proposed.

• Structural Engineering and Mechanics
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• v.12 no.5
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• pp.491-506
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• 2001

In this paper, a new three-dimensional piezoelectric thin shell element containing an integrated distributed piezoelectric sensor and actuator is proposed. The distributed piezoelectric sensor layer monitors the structural shape deformation due to the direct effect and the distributed actuator layer suppresses the deflection via the converse piezoelectric effect. A finite element formulation is presented for static response of laminated shell with piezoelectric sensors/actuators. An eight-node and forty-DOF shell element is built. The performance of the shell elements is improved by reduced integration technique. The static shape control of structure is derived. The shell element is verified by calculating piezoelectric polymeric PVDF bimorph beam. The results agreed with those obtained by theoretical analysis, Tzou and Tseng (1990) and Hwang and Park (1993) fairly well. At last, the static shape control of a paraboloidal antenna is presented.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.3-10
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• 2000

In this study, a new smart beam finite element is proposed for the finite element modeling of the beam-type smart structure with bonded plate-type piezoelectric sensors and actuators. Constitutive equations far the direct piezoelectric effect and converse piezoelectric effect of piezoelectric materials are considered. By using the variational principle, the equations of motion for the smart beam finite element are derived. The presented 2-node beam finite element is isoparametric element based on Timoshenko beam theory. The validity of the proposed beam element is shown through comparing the analysis results of the verification examples with those of other previous researches. Therefore, by analyzing smart structures with smart beam finite elements, it is possible to simulate the control of the structural behavior by piezoelectric actuators with applied voltages and the monitoring of the structure behavior by piezoelectric sensors with sensed voltages.

• Structural Engineering and Mechanics
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• v.19 no.5
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• pp.477-501
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• 2005

In this study, a new smart beam finite element is proposed for the finite element modeling of beam-type smart structures that are equipped with bonded plate-type piezoelectric sensors and actuators. Constitutive equations for the direct piezoelectric effect and converse piezoelectric effect of piezoelectric materials are considered in the formulation. By using a variational principle, the equations of motion for the smart beam finite element are derived. The proposed 2-node beam finite element is an isoparametric element based on Timoshenko beam theory. The proposed smart beam finite element is applied to the free vibration control adopting a constant gain feedback scheme. The electrical force vector, which is obtained in deriving an equation of motion, is the control force equivalent to that in existing literature. Validity of the proposed element is shown through comparing the analytical results of the verification examples with those of other previous researchers. With the use of smart beam finite elements, simulation of free vibration control is demonstrated by sensing the voltage of the piezoelectric sensors and by applying the voltages to the piezoelectric actuators.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.2
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• pp.183-195
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• 2003

In this study, the method of the finite element modeling for free vibration control of beam-type smart structures with bonded plate-type piezoelectric sensors and actuators is proposed. Constitutive equations for the direct piezoelectric effect and converse piezoelectric effect of piezoelectric materials are considered. By using the variational principle, the equations of motion for the smart beam finite element are derived. The proposed 2-node beam finite element is an isoparametric element based on Timoshenko beam theory. Therefore, by analyzing beam-type smart structures with smart beam finite elements, it is possible to simulate the control of the structural behavior by applying voltages to piezoelectric actuators and monitoring of the structural behavior by sensing voltages of piezoelectric sensors. By using the smart beam finite element and constant-gain feed back control scheme, the formulation of the free nitration control for the beam structures with bonded plate-tyPe Piezoelectric sensors and actuators is proposed.

• Journal of Power System Engineering
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• v.13 no.3
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• pp.65-71
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• 2009

This paper presents the energy harvesting technique which is carried out by vibration system with a piezoelectric element. In this study, low frequency characteristics of the piezoelectric element bonded to the aluminum cantilever were experimentally investigated. The piezoelectric element of size of $45L{\times}11W{\times}0.6H$ and piezoelectric constant($d_{31}$ ) of $-180{\times}10^{-12}C/N$ was used. The material of cantilever is an aluminum and two kinds of cantilever of which dimensions are (150, 190)$[mm]{\times}13[mm]{\times}1.5[mm]$ were experimented, respectively. The cantilever was fixed on the magnetic type vibrator and the vibrator was operated by power input with a sine wave. The characteristics of requency and mass variation of cantilever end part such as 0, 2.22, 4.34, 5.87, 8.66, 11.01 [g] were investigated. Finally, this paper suggests a method of generating electrical energy with a piezoelectric element using wind, an energy source that is easily applied and from which we can obtain "clean" energy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.250-259
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• 2010

The ability for energy harvesting via the piezoelectric effect was studied for a unimorph element such as piezo buzzer. A simple equivalent circuit was proposed to predict the energy generated based on the internal stress. Unimorphs with a metal-cavity were used as a driving device of the generation panel. Both the AC open voltage and DC output voltage as a function of pressure period and number of element were measured. For the unimorph generation circuit, DC output voltage varies with pressure period, reaching a maximum value at $470{\mu}F$. The maximum output voltage a according to load resistance was measured at $1M{\Omega}$. Data analysis of the DC output voltage and time constant indicated that number of piezoelectric element of optimum was 60~80. It was found that piezoelectric unimorph has the possibility to be used as the driving element of the electric generation.

• Smart Structures and Systems
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• v.16 no.6
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• pp.1091-1105
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• 2015

Piezoelectric coefficient and dielectric constant of PZT-5H vary with electric field. In this work, variations of these coefficients with electric field are included in finite element modelling of a cantilevered plate instrumented with piezoelectric patches. Finite element model is reduced using modal truncation and then converted into state-space. First three modal displacements and velocities are estimated using Kalman observer. Negative first modal velocity feedback is used to control the vibrations of the smart plate. Three cases are considered v.i.z case 1: in which variation of piezoelectric coefficient and dielectric constant with electric field is not considered in finite element model and not considered in Kalman observer, case 2: in which variation of piezoelectric coefficient and dielectric constant with electric field is considered in finite element model and not considered in Kalman observer and case 3: in which variation of piezoelectric coefficient and dielectric constant with electric field is considered in finite element model as well as in Kalman observer. Simulation results show that appreciable amount of change would appear if variation of piezoelectric coefficient and dielectric constant with r.m.s. value of electric field is considered.

• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.411-420
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• 2010

In general, moving vehicles generate continuous and repetitive strain of energy on bridges. The strain energy can convert to electric energy due to its piezoelectric element. However, some factors should be considered in order to reasonably assess the feasibility such as load distribution applied on bridges and the relationship of strains generated according to loads. This study was carried out to estimate the generated voltage when piezoelectric elements were installed to a bridge. A steel-concrete composite specimen was fabricated and loads were applied, considering vehicle load-effects. As a result, the voltage generated in the element was evaluated and compared with the analysis equation of the piezoelectric effect.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.204-209
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• 2000

It is the first step to establish the exact vibration model of the structure when constructing the smart structure with desired vibration scheme. In this paper, vibration model of beam with piezoelectric element boned on the surface is presented by considering the thickness effect of the bond layer. In contrast to the previous papers which neglect the effect of bond layer, the presented vibration model considers the effect of bond layer assuming the prefect bond condition. The perfect bond condition is tested by comparing the controllability of beams with three types of bond layer. An optimal vibration control of the beam can be performed when there exists perfect-bond condition between the piezoelectric element and the main structure.