Active control effort of hybrid piezoelectric absorber for structural control

This paper aims at addressing the active control effort of the active-shunted hybrid piezoelectric absorber for structural vibration suppression. Both active control efforts of the integrated and separated hybrid piezoelectric absorbers are analyzed by using a simple cantilevered beam example. It is recognized that a new hybrid piezoelectric absorber based on a switching operation is capable of reducing the active control effort. A switching type of the hybrid piezoelectric absorber can be developed by the simple combination of integrated and separated hybrid piezoelectric absorbers. It is demonstrated that the switching type of the absorber has the capability of the trade-off between the active control effort and the damping performance.     

Coupled FEM/BEM for control of noise radiation and sound transmission using piezoelectric shunt damping

In this paper, we present a coupled finite element/boundary element method (FEM/BEM) for control of noise radiation and sound transmission of vibrating structure by passive piezoelectric techniques. The system consists of an elastic structure (with surface mounted piezoelectric patches) coupled to external/internal acoustic domains. The passive shunt damping strategy is employed for vibration attenuation in the low frequency range. The originality of the present paper lies in evaluating the classically used FEM/BEM methods for structural–acoustics problems when taking account smart systems at the fluid–structure interfaces.     

FEM dynamic model for active vibration control of flexible linkages and its application to a planar parallel manipulator

Development of dynamic models of flexible linkages, with flexible motion caused by rigid body motion and electromechanical coupling of transduction devices and the host linkage, is very important for the design of active vibration control laws for flexible-link mechanisms. In the first part of this paper, the Lagrange finite element (FE) formulation is used to derive such a dynamic model for a flexible planar linkage with two translational and one rotational degrees of freedom. Linear electromechanical coupling of surface-bonded lead zirconate titanate (PZT) patches with the host linkage is incorporated into the model. In the second part of this paper, this dynamic model is applied to a flexible-link planar parallel manipulator. Based on standard kineto-elastodynamic assumptions, the linkage dynamic model is simplified and simulation of strain rate feedback control using PZT sensors and actuators is performed. Numerical results show that PZT actuators effectively damp vibration of the flexible linkages.     

Review of the design of power ultrasonic generator for piezoelectric transducer

The power ultrasonic generator (PUG) is the core device of power ultrasonic technology (PUT), and its performance determines the application of this technology in biomedicine, semiconductor, aerospace, and other fields. With the high demand for sensitive and accurate dynamic response in power ultrasonic applications, the design of PUG has become a hot topic in academic and industry. However, the previous reviews cannot be used as a universal technical manual for industrial applications. There are many technical difficulties in establishing a mature production system, which hinder the large-scale application of PUG for piezoelectric transducers. To enhance the performance of the dynamic matching and power control of PUG, the studies in various PUT applications have been reviewed in this article. Initially, the demand design covering the piezoelectric transducer application and parameter requirements for ultrasonic and electrical signals is overall summarized, and these parameter requirements have been recommended as the technical indicators of developing the new PUG. Then the factors affecting the power conversion circuit design are analyzed systematically to realize the foundational performance improvement of PUG. Furthermore, advantages and limitations of key control technologies have been summarized to provide some different ideas on how to realize automatic resonance tracking and adaptive power adjustment, and to optimize the power control and dynamic matching control. Finally, several research directions of PUG in the future have been prospected.     

Comparison of wurtzite atomistic and piezoelectric continuum strain models: Implications for the electronic band structure

We compare continuum and atomistic models for the electromechanical fields in wurtzite GaN/AlN quantum dots and their relative impact on the electronic band structure. Qualitative agreement between atomistic strain calculations and continuum elastic models for a wurtzite hexagonal quantum-dot structure is demonstrated; however, significant quantitative discrepancies of up to 100 meV are observed. A smaller difference of approximately 15 meV is found between fully coupled and semi-coupled continuum models.