An Active-Passive Piezoelectric Absorber for Structural Vibration Control Under Harmonic Excitations With Time-Varying Frequency, Part 1: Algorithm Development and Analysis

2001 ◽  
Vol 124 (1) ◽  
pp. 77-83 ◽  
Author(s):  
R. A. Morgan ◽  
K. W. Wang
Keyword(s):  
Active Control ◽  
High Performance ◽  
Piezoelectric Materials ◽  
Negative Resistance ◽  
Electrical Circuit ◽  
Structural Vibration ◽  
Experimental Investigations ◽  
Electrical Networks ◽  
Practical Applications ◽  
Harmonic Excitations

It has been shown that piezoelectric materials can be used as passive electromechanical vibration absorbers by shunting them with electrical networks. Semi-active piezoelectric absorbers have also been proposed for suppressing harmonic excitations with varying frequency. However, these semi-active devices have limitations that restrict their practical applications. The approach presented here is a high performance active-passive alternative to semi-active absorbers. By utilizing a combination of a passive electrical circuit and active control actions, the system is synthesized for adaptive variable frequency narrowband disturbance rejection. The active control consists of three parts: an inductor tuning action, a negative resistance action, and a coupling enhancement action. In the current paper (Part 1), the control algorithm is developed and analyzed. Part 2 of the paper contains experimental investigations and parametric studies of the new absorber design.

An Active-Passive Piezoelectric Vibration Absorber for Structural Control Under Harmonic Excitations With Time-Varying Frequency

2000 ◽  
Author(s):  
Ronald A. Morgan ◽  
K. W. Wang
Keyword(s):  
Active Control ◽  
Structural Control ◽  
High Performance ◽  
Piezoelectric Materials ◽  
Negative Resistance ◽  
Electrical Circuit ◽  
Superior Performance ◽  
Electrical Networks ◽  
Harmonic Excitations ◽  
Time Varying Frequency

Abstract It has been shown that piezoelectric materials can be used as passive electromechanical vibration absorbers when shunted by electrical networks. Semi-active piezoelectric absorbers have also been proposed for suppressing harmonic excitations with varying frequency. However, these semi-active devices have limitations that restrict their applications. The design presented here is a high performance active-passive alternative to semi-active absorbers that uses a combination of a passive electrical circuit and active control actions. The active control consists of three parts: an adaptive inductor tuning action, a negative resistance action, and a coupling enhancement action. A formulation for the optimal tuning of the piezoelectric absorber inductance on a multiple degree of freedom (MDOF) structure is derived. The effectiveness of the proposed system is demonstrated experimentally on a system under a variable frequency excitation. Extensive parameter studies are also carried out to show that the proposed design offers superior performance and efficiency compared to other state-of-the-art control methods.

An Active-Passive Piezoelectric Absorber for Structural Vibration Control Under Harmonic Excitations With Time-Varying Frequency, Part 2: Experimental Validation and Parametric Study

2001 ◽  
Vol 124 (1) ◽  
pp. 84-89 ◽  
Author(s):  
R. A. Morgan ◽  
K. W. Wang
Keyword(s):  
High Performance ◽  
Superior Performance ◽  
Structural Vibration ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Attractive Alternative ◽  
Structural Vibration Control ◽  
Harmonic Excitations ◽  
Time Varying Frequency ◽  
Parametric Studies

In Part 1 of the paper, a new high-performance active-passive hybrid piezoelectric absorber concept was presented. This design is an attractive alternative to semi-active absorbers for the purpose of suppressing harmonic excitations with variable frequency. In this paper (Part 2), the effectiveness of the new absorber design is first demonstrated through experimental investigations. Parametric studies are then carried out to illustrate how the performance of the new design is affected by the design parameters and excitation characteristics. In these studies, two state-of-the-art control methods are used as baselines for comparison with the new absorber design, and it is shown that the proposed design offers superior performance and efficiency compared to these methods.

A Comparative Study of Actively Controlled and Shunted Piezoelectric Materials for Structural Damping

2007 ◽  
Author(s):  
Mehdi Ahmadian
Keyword(s):  
Active Control ◽  
Piezoelectric Materials ◽  
Structural Vibration ◽  
Structural Damping ◽  
Test Plate ◽  
Plate Vibrations ◽  
Positive Position Feedback ◽  
Position Feedback ◽  
Control Authority ◽  
Circuit Technique

A comparison between actively-controlled piezoelectric (PZT) material with positive position feedback (PPF) and a parallel resistor-inductor shunt circuit technique is provided. This study focuses on the performance of each technique at reducing structural vibration on a test plate for both narrowband and broadband frequency reductions. The comparison between the shunted and active PZT damping techniques used in this study shows that active control with positive position feedback was more effective at controlling vibrations of a test plate. The active PZT method was able to add damping to each of the modes targeted in the frequency range of interest. In addition, active control with positive position feedback was able to achieve this level of control authority with a single PZT patch located in the center of the test plate. Conversely, shunted PZTs used three PZT actuators to reduce the test plate vibrations. The results show that actively-controlled PZTs can provide much more damping per square area of PZT than shunted PZTs, by as much as four times more.

An Energy-Based Parametric Control Approach for Structural Vibration Suppression via Semi-Active Piezoelectric Networks

1996 ◽  
Vol 118 (3) ◽  
pp. 505-509 ◽  
Author(s):  
K. W. Wang ◽  
J. S. Lai ◽  
W. K. Yu
Keyword(s):  
Vibration Suppression ◽  
Mechanical Energy ◽  
Electrical Circuit ◽  
Structural Vibration ◽  
Structure Stability ◽  
Total System ◽  
Electrical Networks ◽  
Main Structure ◽  
Control Approach ◽  
Parametric Control

A structural vibration control concept, using piezoelectric materials shunted with real-time adaptable electrical networks, has been investigated. The variable resistance and inductance in an external RL circuit are used as control inputs. An energy-based parametric control scheme is created to reduce the total system energy (the main structure mechanical energy plus the electrical and mechanical energies of the piezoelectric material and electrical circuit) while minimizing the energy flowing into the main structure. Stability of the closed-loop system is proved. The performance of the controller is examined through analyzing a beam example. It is shown that the structure energy level and vibration amplitude can be suppressed effectively.

Experimental investigations on active control of multifrequency helicopter vibrations using discrete model predictive sliding mode control

2017 ◽  
Vol 232 (15) ◽  
pp. 2898-2909
Author(s):  
Xunjun Ma ◽  
Yang Lu ◽  
Fengjiao Wang
Keyword(s):  
Active Control ◽  
Discrete Model ◽  
Sliding Mode ◽  
Structural Response ◽  
Test System ◽  
Experimental Investigations ◽  
Least Mean Square ◽  
Single Input Single Output ◽  
Control Approach ◽  
Practical Applications

The presented experimental results illustrate the recent advances in the reduction of multifrequency vibrations of helicopter fuselage using an active control of structural response system. Recently, to cancel the multifrequency helicopter vibrations, a hybrid control approach has been proposed combining the filtered-x least mean square algorithm with a discrete model predictive sliding mode controller. To verify its effectiveness and self-adaptability, a set of active control experiments of structural response are conducted on a free–free elastic beam, which simulates a helicopter in flight. Considering that the helicopter vibrations in practical applications are much more complex, the further experiments of real-time active control are performed using a model helicopter test system. Higher discrete frequency components, which are actually of concern, are selected as the control objectives during the tests. The algorithm’s control effects are sufficiently checked by single-input single-output and multiple-input multiple-output tests under different excitation conditions. For many cases the attenuation of measured response exceed level of 20 dB, with maximum reduction reaching 34.1 dB. These two sets of tests confirm that the active control system is practical for canceling the multifrequency helicopter vibrations.

scholarly journals Flux Method Growth of Large Size Group IV–V 2D GeP Single Crystals and Photoresponse Application

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 235
Author(s):  
Shuqi Zhao ◽  
Tongtong Yu ◽  
Ziming Wang ◽  
Shilei Wang ◽  
Limei Wei ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Single Crystals ◽  
High Performance ◽  
Group Iv ◽  
X Ray Diffraction ◽  
High Quality ◽  
Practical Applications ◽  
Large Size ◽  
Growth Method ◽  
Polarized Raman

Two-dimensional (2D) materials driven by their unique electronic and optoelectronic properties have opened up possibilities for their various applications. The large and high-quality single crystals are essential to fabricate high-performance 2D devices for practical applications. Herein, IV-V 2D GeP single crystals with high-quality and large size of 20 × 15 × 5 mm3 were successfully grown by the Bi flux growth method. The crystalline quality of GeP was confirmed by high-resolution X-ray diffraction (HRXRD), Laue diffraction, electron probe microanalysis (EPMA) and Raman spectroscopy. Additionally, intrinsic anisotropic optical properties were investigated by angle-resolved polarized Raman spectroscopy (ARPRS) and transmission spectra in detail. Furthermore, we fabricated high-performance photodetectors based on GeP, presenting a relatively large photocurrent over 3 mA. More generally, our results will significantly contribute the GeP crystal to the wide optoelectronic applications.

scholarly journals Analysis of a Linear Model for Non-Synchronous Vibrations Near Stall

2021 ◽  
Vol 6 (3) ◽  
pp. 26
Author(s):  
Christoph Brandstetter ◽  
Sina Stapelfeldt
Keyword(s):  
Linear Model ◽  
Linear Models ◽  
Structural Vibration ◽  
Experimental Investigations ◽  
Vibration Modes ◽  
Critical Problem ◽  
Safety Critical ◽  
Unstable Vibration ◽  
Aero Engines ◽  
Lock In

Non-synchronous vibrations arising near the stall boundary of compressors are a recurring and potentially safety-critical problem in modern aero-engines. Recent numerical and experimental investigations have shown that these vibrations are caused by the lock-in of circumferentially convected aerodynamic disturbances and structural vibration modes, and that it is possible to predict unstable vibration modes using coupled linear models. This paper aims to further investigate non-synchronous vibrations by casting a reduced model for NSV in the frequency domain and analysing stability for a range of parameters. It is shown how, and why, under certain conditions linear models are able to capture a phenomenon, which has traditionally been associated with aerodynamic non-linearities. The formulation clearly highlights the differences between convective non-synchronous vibrations and flutter and identifies the modifications necessary to make quantitative predictions.

scholarly journals Copper-graphene heterostructure for back-end-of-line compatible high-performance interconnects

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Myungwoo Son ◽  
Jaewon Jang ◽  
Yongsu Lee ◽  
Jungtae Nam ◽  
Jun Yeon Hwang ◽  
...  
Keyword(s):  
High Performance ◽  
Direct Synthesis ◽  
Chemical Vapor ◽  
Multilayer Graphene ◽  
Time To Failure ◽  
Practical Applications ◽  
Cu Interconnects ◽  
Pressure Chemical ◽  
Cu Interconnect ◽  
Pure Cu

AbstractHere, we demonstrate the fabrication of a Cu-graphene heterostructure interconnect by the direct synthesis of graphene on a Cu interconnect with an enhanced performance. Multilayer graphene films were synthesized on Cu interconnect patterns using a liquid benzene or pyridine source at 400 °C by atmospheric pressure chemical vapor deposition (APCVD). The graphene-capped Cu interconnects showed lower resistivity, higher breakdown current density, and improved reliability compared with those of pure Cu interconnects. In addition, an increase in the carrier density of graphene by doping drastically enhanced the reliability of the graphene-capped interconnect with a mean time to failure of >106 s at 100 °C under a continuous DC stress of 3 MA cm−2. Furthermore, the graphene-capped Cu heterostructure exhibited enhanced electrical properties and reliability even if it was a damascene-patterned structure, which indicates compatibility with practical applications such as next-generation interconnect materials in CMOS back-end-of-line (BEOL).

scholarly journals Particle Size Effect of Lanthanum-Modified Bismuth Titanate Ceramics on Ferroelectric Effect for Energy Harvesting

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Sangmo Kim ◽  
Thi My Huyen Nguyen ◽  
Rui He ◽  
Chung Wung Bark
Keyword(s):  
Particle Size ◽  
Energy Harvesting ◽  
High Speed ◽  
High Performance ◽  
Bismuth Titanate ◽  
Vinylidene Fluoride ◽  
Piezoelectric Materials ◽  
Renewable Energy Sources ◽  
Particle Size Effect ◽  
Ferroelectric Materials

AbstractPiezoelectric nanogenerators (PNGs) have been studied as renewable energy sources. PNGs consisting of organic piezoelectric materials such as poly(vinylidene fluoride) (PVDF) containing oxide complex powder have attracted much attention for their stretchable and high-performance energy conversion. In this study, we prepared a PNG combined with PVDF and lanthanum-modified bismuth titanate (Bi4−XLaXTi3O12, BLT) ceramics as representative ferroelectric materials. The inserted BLT powder was treated by high-speed ball milling and its particle size reduced to the nanoscale. We also investigated the effect of particle size on the energy-harvesting performance of PNG without polling. As a result, nano-sized powder has a much larger surface area than micro-sized powder and is uniformly distributed inside the PNG. Moreover, nano-sized powder-mixed PNG generated higher power energy (> 4 times) than the PNG inserted micro-sized powder.

scholarly journals Computational and experimental investigations of one-step conversion of poly(carbonate)s into value-added poly(aryl ether sulfone)s

2016 ◽  
Vol 113 (28) ◽  
pp. 7722-7726 ◽  
Author(s):  
Gavin O. Jones ◽  
Alexander Yuen ◽  
Rudy J. Wojtecki ◽  
James L. Hedrick ◽  
Jeannette M. García
Keyword(s):  
High Performance ◽  
Density Functional ◽  
Value Added ◽  
Single Step ◽  
Nucleophilic Attack ◽  
Experimental Investigations ◽  
Aryl Ether ◽  
One Step ◽  
Poly Carbonate

It is estimated that ∼2.7 million tons poly(carbonate)s (PCs) are produced annually worldwide. In 2008, retailers pulled products from store shelves after reports of bisphenol A (BPA) leaching from baby bottles, reusable drink bottles, and other retail products. Since PCs are not typically recycled, a need for the repurposing of the PC waste has arisen. We report the one-step synthesis of poly(aryl ether sulfone)s (PSUs) from the depolymerization of PCs and in situ polycondensation with bis(aryl fluorides) in the presence of carbonate salts. PSUs are high-performance engineering thermoplastics that are commonly used for reverse osmosis and water purification membranes, medical equipment, as well as high temperature applications. PSUs generated through this cascade approach were isolated in high purity and yield with the expected thermal properties and represent a procedure for direct conversion of one class of polymer to another in a single step. Computational investigations performed with density functional theory predict that the carbonate salt plays two important catalytic roles in this reaction: it decomposes the PCs by nucleophilic attack, and in the subsequent polyether formation process, it promotes the reaction of phenolate dimers formed in situ with the aryl fluorides present. We envision repurposing poly(BPA carbonate) for the production of value-added polymers.

Sign in / Sign up

Export Citation Format

Share Document