Lightweight Piezo-composite Actuator Research Articles

Integrated Localized MicroCooling Using High-Displacement Piezoelectric Actuators

RF communication and radar systems present an extreme thermal management challenge. These systems are comprised of tightly packaged, high-power components requiring a controlled temperature to meet performance and reliability parameters. In these systems, there is little space available for macro-scale air flow or other traditional cooling methods. In addition, heat generating components are typically microscale semiconductor devices fabricated on integrated circuit substrates buried deeply within the system. Localized cooling using integrated microsystems may provide a solution to these thermal management issues. One approach is the integration of miniature synthetic air jets near the heat generating components. Synthetic jets are generated using oscillating piezoelectric actuators that force air through a small nozzle at high flow rates and in close proximity to the heat generating component. The resulting jets provide vorticity within the fluid, leading to enhanced mixing with the surrounding lower temperature environment and a subsequent increase in the heat transfer coefficient. The US Army AMRDEC has been developing and operating microactuator test beds, utilizing high-displacement actuator architectures, including THUNDER and Lightweight Piezo-Composite Actuator (LIPCA) approaches, to reduce actuator size while maintaining sufficient flow rates and vorticity. This investigation has modeled and fabricated potential high-displacement miniature actuators, as well as predicted and characterized resulting jet parameters and heat transfer coefficients utilizing these actuators. This paper will present actuator designs, fabrication process, and cooling results using these high-displacement piezoelectric actuators as the drive element.

Increment thrust of fish robot by using Compressed Unimorth Piezoelectric Composite Actuator

In this work, we have presented a fish robot actuated by four compressed light-weight piezo-composite actuators. Swimming speed, thrust, and drag of the fish robot were experimentally examined to verify effect of the applied compressive force on force actuation, consequently on swimming speed of fish robot. The swimming speed of the fish robot was measured for four different tail fin areas. The drag of the fish robot was estimated by experiment and computational fluid dynamics (CFD) simulation. For drag measurement, we have presented an apparatus to measure relatively small drag by using a high speed camera. The measured drag agreed well with the calculated one by the CFD. We have also suggested a thrust measurement apparatus, where we can ignore effect of vibratory motion of the system. The thrust of the fish robot was increased about 11% due to the applied compressive force on the piezoceramic actuators. However, the drag of the fish robot was also increased due to increment of the cross section area.

Actuation characterization of the lightweight unimorph piezo-composite actuator for different loading cases

In this study, we focused on the actuation behavior of the lightweight piezo-composite unimorph actuator (LIPCA). Common loading configurations found in real applications of LIPCA have been studied including the center loading and tip loading cases. The domain switching effect that has strong influence on the performance of LIPCA was recorded. While a longitudinally compressed stress state within the PZT (lead zirconate titanate, Pb[Zr(x)Ti(1–x)]O3) layer in LIPCA is preferable to avoid failure during operation, experimental results showed that, for the transverse loading cases, the actuator should be arranged in a manner such that the stress state within the PZT is in as much tension as possible to encourage the non-180° domain switching. With investigated loading cases in this paper, suitable arrangements could help improve the actuation performance. The improvement can be up to almost 33% in simply-supported with center loading and 140% in clamped tip loading case.

Development of a Peristaltic Micropump with Lightweight Piezo-Composite Actuator Membrane Valves

A peristaltic micropump with lightweight piezo-composite actuator (LIPCA) membrane valves is presented. The micropump contained three cylinder chambers that were connected by microchannels and two active membrane valves. A circular miniature LIPCA was developed and manufactured to be used as actuating diaphragms. The LIPCA diaphragm acted as an active membrane valve that alternate between open and closed positions at the inlet and outlet in order to produce high pumping pressure. In this LIPCA, a lead zirconium titanate ceramic with a thickness of 0.1 mm was used as an active layer. The results confirmed that the actuator produced a large out-of-plane deflection. During the design process, a coupled field analysis was conducted in order to predict the actuating behavior of the LIPCA diaphragm; the behavior of the actuator was investigated from both a theoretical and experimental perspective. The active membrane valve concept was introduced as a means for increasing pumping pressure, and microelectromechanical system techniques were used to fabricate the peristaltic micropump. The pumping performance was analyzed experimentally in terms of the flow rate, pumping pressure and power consumption.

Modification of a Four-Bar Linkage System for a Higher Optimal Flapping Frequency

The goal of this work is to increase the optimal flapping frequency, at which the flapper produces maximum vertical force, of a previously developed flapper actuated by a lightweight piezocomposite actuator (LIPCA). We tested the dynamic response of the LIPCA and conducted a parametric study of a four-bar linkage system. An appropriate combination of linkage lengths can provide a better moment transmission and enhance the optimal flapping frequency. The newly designed flapper was tested with five different flapping frequencies. The experimental results confirm that the optimal flapping frequency of the modified flapper is about 17 Hz, and the flapping angle is 92°. The results show 70% increase in the optimal flapping frequency; however, only 8% decrease in the flapping angle compared with the corresponding values of the previous flapper. The highest vertical force produced by the newly designed flapper is 3.6 g at the optimal flapping frequency.

Modeling and Design of H-Infinity Controller for Piezoelectric Actuator LIPCA

We proposed a dynamic model identification and design of an H-Infinity (i.e. H 8) controller using a Lightweight Piezo-Composite Actuator (LIPCA). A second-order dynamic model was obtained by using input and output data, and applying an identification algorithm. The identified model coincides well with the real LIPCA. To reduce the resonating mode that is typical of piezoelectric actuators, a notch filter was used. A feedback controller using the H 8 control scheme was designed based on the identified dynamic model; thus, the LIPCA can be easily used as an actuator for biomemetic applications such as artificial muscles or macro/micro positioning in bioengineering. The control algorithm was implemented using a microprocessor, analog filters, and power amplifying drivers. Our simulation and experimental results demonstrate that the proposed control algorithm works well in real environment, providing robust performance and stability with uncertain disturbances.

Performance evaluation of an improved fish robot actuated by piezoceramic actuators

This paper presents an improved fish robot actuated by four lightweight piezocompositeactuators. Our newly developed actuation mechanism is simple to fabricate because itworks without gears. With the new actuation mechanism, the fish robot has a 30% smallercross section than our previous model. Performance tests of the fish robot in waterwere carried out to measure the tail-beat angle, the thrust force, the swimmingspeed for various tail-beat frequencies from 1 to 5 Hz and the turning radius atthe optimal frequency. The maximum swimming speed of the fish robot is 7.7 cm s − 1 at a tail-beat frequency of 3.9 Hz. A turning experiment shows that the swimming directionof the fish robot can be controlled by changing the duty ratio of the driving voltage; thefish robot has a turning radius of 0.41 m for a left turn and 0.68 m for a right turn.

무밸브 마이크로 펌프의 성능평가를 위한 3차원 전기-유체-구조 상호작용 해석

본 논문에서는 압전 작동기로 구동되는 무밸브 마이크로 펌프의 펌프 성능을 계산하였다. 선행연구에서 개발된 마이크로 펌프는 4층의 경량 압전 복합재료 작동기, PDMS로 된 챔버와 2개의 디퓨져로 이루어져 있다. 유한요소 해석은 압전 영역, 구조 영역 및 유체 영역을 완전 연성하여 수행되었다. 구조 및 압전 영역의 해석은 ANSYS를 사용하였으며, 유체영역의 해석은 ANSYS CFX를 사용하여 수행하였다. 작동 주파수가 10 Hz와 40 Hz인 경우에 대한 해석을 수행하여 작동 주파수가 유동 특성에 미치는 영향을 고찰하였다. 또한 300 Hz까지의 유동 해석을 통하여 작동 주파수에 따른 유량을 계산하였다. In this study, the pumping performance of a piezoelectric valveless micropump is simulated. The micropump, which was developed in the previous work, is composed of a four-layer lightweight piezocomposite actuator, a polydimethylsiloxane (PDMS) pump chamber, and two diffusers. The piezoelectric domain, the fluid domain and the structural domain are coupled in the three-dimensional simulation. We used ANSYS for the piezoelectric and structural domains and ANSYS CFX for the fluid domain. The effects of driven frequency on the flow rate have been investigated by simulating the flow characteristics for 10 Hz and 40 Hz driven frequencies. The flow rates with respect to driven frequencies up to 300 Hz have been calculated.

A fish robot driven by piezoceramic actuators and a miniaturized power supply

In this paper, we have introduced a prototype of a fish robot driven by unimorph piezoceramic actuators. To improve the swimming performance of the fish robot in terms of tail-beat angle, swimming speed, and thrust force, we used four light-weight piezo-composite actuators (LIPCAs) instead of the two LIPCAs used in the previous model. We also developed a new actuation mechanism consisting of links and gears. Performance tests of the fish robot were conducted in water at various tail-beat frequencies to measure the tail-beat angle, swimming speed, and thrust force. The tail-beat angle was significantly better than that of the previous model. The best tail-beat frequency of the fish robot was 1.4 Hz and the maximum thrust force was 0.0048 N. A miniaturized power supply, which was developed to excite the LIPCAs, was installed inside the fish robot body for free swimming. The maximum free-swimming speed was 3.2 cm/s.

Design and Experimental Parameteric Study of a Fish Robot Actuated by Piezoelectric Actuators

This paper presents the design and experimental parametric study of a biomimetic fish robot actuated by two lightweight piezo-composite actuators. The biomimetic aspects in this work are the mimicking of an oscillating tail-beat motion and the shape of an artificial caudal fin. Artificial caudal fins that resemble the fins of fish propelled by the body-and-caudal fin mode are fabricated for a parametric study of the way caudal fin characteristics affect the production of thrust at an operating frequency range. The observed caudal fin characteristics are the shape, area, and aspect ratio. A caudal fin with a high aspect ratio contributes to the high swimming speed of the present fish platform. A fish robot propelled by an artificial caudal fin shaped like the fin of a thunniform fish, which has a relatively high aspect ratio, produces a swimming speed as high as 2.364 cm/s for a 300 Vpp input voltage excited at 0.9Hz. The thrust performance of the biomimetic fish robot is examined in terms of the Strouhal number, the Froude number, the Reynolds number, and power consumption.

Development of a Peristaltic Micropump for Bio-Medical Applications Based on Mini LIPCA

This paper presents the design, fabrication, and experimental characterization of a peristaltic micropump. The micropump is composed of two layers fabricated from Polydimethylsiloxane (PDMS) material. The first layer has a rectangular channel and two valve seals. Three rectangular mini lightweight piezo-composite actuators are integrated in the second layer, and used as actuation parts. Two layers are bonded, and covered by two Polymethyl Methacrylate (PMMA) plates, which help increase the stiffness of the micropump. A maximum flow rate of 900 μL·min −1 and a maximum backpressure of 1.8 kPa are recorded when water is used as pump liquid. We measured the power consumption of the micropump. The micropump is found to be a promising candidate for bio-medical application due to its bio-compatibility, portability, bidirectionality, and simple effective design.

시뮬레이션을 통한 무밸브 마이크로 펌프의 전기-유체-구조 상호작용에 대한 연구

본 논문에서는 유한요소법을 기반으로 한 소프트웨어 COMSOL Multiphysics를 이용하여 압전 복합재료 작동기를 이용하여 제작한 무밸브 마이크로펌프의 성능을 연구하였다. 압전 마이크로펌프는 4층의 경량 압전 복합재료 작동기, PDMS으로 된 챔버와 2개의 디퓨저로 이루어졌다. 시뮬레이션에서는 압전 재료 영역, 구조 영역과 유체 영역을 완전 연성하여 해를 계산하였다. 물을 유체로 사용하였으며, 유량을 마이크로펌프의 구조적 파라미터에 대하여 계산하였다. 이 연구에 기초하여 보다 성능이 좋은 마이크로펌프를 제시하였다. In this paper, the pumping performance of a piezoelectric valveless micropump is simulated with a commercial finite element analysis software, COMSOL Multiphysics. The micropump developed in the previous work is composed of a 4-layer lightweight piezo-composite actuator (LIPCA), a polydimethylsiloxane (PDMS) pump chamber, and two diffusers. The piezoelectric domain, structural domain and fluid domain are coupled in the simulation. Water flow rates are numerically predicted for geometric parameters of the micropump. Based on this study, the micropump is optimally designed to obtain its highest pumping performance.

Effect of an Artificial Caudal Fin on the Performance of a Biomimetic Fish Robot Propelled by Piezoelectric Actuators

This paper addresses the design of a biomimetic fish robot actuated by piezoceramic actuators and the effect of artificial caudal fins on the fish robot's performance. The limited bending displacement produced by a lightweight piezocomposite actuator was amplified and transformed into a large tail beat motion by means of a linkage system. Caudal fins that mimic the shape of a mackerel fin were fabricated for the purpose of examining the effect of caudal fin characteristics on thrust production at an operating frequency range. The thickness distribution of a real mackerel's fin was measured and used to design artificial caudal fins. The thrust performance of the biomimetic fish robot propelled by fins of various thicknesses was examined in terms of the Strouhal number, the Froude number, the Reynolds number, and the power consumption. For the same fin area and aspect ratio, an artificial caudal fin with a distributed thickness shows the best forward speed and the least power consumption.

Actuation Performance Improvement of Lightweight Piezo-Composite Actuator with an Inter Digital Electrode Actuation Layer

Actuation Performance Improvement of Lightweight Piezo-Composite Actuator with an Inter Digital Electrode Actuation Layer

Application of a LIPCA for the structural vibration suppression of an aluminum cantilever beam with a tip mass

Use of bare PZT as an actuator in the field of active vibration suppression may cause some drawbacks such as critical breaks in the installation process, short circuits in the host material and low fatigue performance. To alleviate these problems, we developed a new actuator called a lightweight piezocomposite actuator (LIPCA). The LIPCA has five layers: three glass-epoxy layers, a carbon-epoxy layer and a PZT layer. We implemented a LIPCA as an actuator to suppress the vibration of an aluminum cantilever beam with a tip mass. For the control algorithm in our test, we used positive position feedback. The filter frequency for this type of feedback should be tuned to the frequency of the target mode. The first three experimental natural frequencies of the aluminum cantilever beam agree well with the results of finite element methods. The effectiveness of using a LIPCA as an actuator in active vibration suppression was investigated with respect to the time and frequency domains, and the experimental results show that LIPCAs can significantly reduce the amplitude of forced vibrations as well as the settling time of free vibrations.

경량 압전 복합재료 작동기를 이용한 끝단 질량이 부착된 보의 진동 제어

PZT와 같은 압전 재료는 능동 진동 억제 분야에서 널리 사용되고 있지만 단일 PZT의 경우 장착 과정에서의 손상, 전기 누전, 낮은 피로 성능과 같은 문제가 지적되고 있다. 이러한 문제를 해결하기 위하여 개발된 LIPCA 작동기는 여러 층의 복합재료와 PZT 층으로 구성되어 있다. 본 연구에서는 LIPCA 작동기를 끝단 질량이 부착된 알루미늄 외팔보의 진동을 억제하는데 적용하였다. 양변위 되먹임 제어 알고리듬을 사용하였으며, 필터 주파수를 대상 모드의 첫 번째 고유진동수에 맞추었다. 실험적으로 구한 알루미늄 보의 고유 진동수는 유한요소 해석의 결과와 잘 일치하였다. LIPCA 작동기를 능동 진동제어에 적용할 때 효율성을 시간과 주파수 영역에서 확인하고자 하였는데, 실험 결과 PPF제어를 사용한 LIPCA 작동기가 자유 진동의 안정화 시간과 강제 진동의 진폭을 효과적으로 제어할 수 있었다. 사례 연구로 다른 두께를 가지는 보의 강제 진동 제어를 수행하였다. Although piezoelectric materials such as PZT have been widely used as actuators in the field of active vibration suppression, the use of bare PZT as an actuator may cause some drawbacks such as critical breaks in the installation process, short circuits in the host material and low fatigue performance. The LIPCA-C2 (lightweight piezocomposite actuator) was developed to alleviate these problems. We implemented the LIPCA as an actuator to suppress the vibration of an aluminum cantilever beam with a tip mass. In our test, we used positive position feedback control algorithm. The filter frequency for this type of feedback should be tuned to the natural frequency of the target mode. The first three experimental natural frequencies of the aluminum cantilever beam agree well with the results of finite element analysis. The effectiveness of using the LIPCA as an actuator in active vibration suppression was investigated with respect to the time and frequency domains, and the experimental results show that LIPCAs with PPF control can significantly reduce the amplitude of forced vibrations and the settling time of free vibrations. For a case study, the forced vibration control of several beams with different thicknesses were performed.

Use of Lightweight Piezo-composite Actuators to Suppress the Free Vibration of an Aluminum Beam

A lightweight piezo-composite actuator (LIPCA) is used to suppress the vibration of an aluminum beam. Composed of a piezoelectric layer, a carbon-epoxy layer, and glass-epoxy layers, the LIPCA has better performance and durability than bare piezoelectric ceramics (PZT). This study estimates the actuation performances of a LIPCA in an active vibration control as well as a static actuation test. Experiments are performed on an aluminum beam in a cantilever configuration. The LIPCA, a bare PZT, and a 3GE+PZT actuator are attached to the aluminum beam with adhesive in order to investigate their performance. A comparison of the equivalent actuation moment and the tip deflection of the beam between the LIPCA, the bare PZT, and the 3GE + PZT actuator shows that the LIPCA has a better actuation performance than the bare PZT and the 3GE + PZT actuator. In addition, a digital PID control algorithm is applied to the active vibration control system to show how the LIPCA performs as an actuator in an active vibration suppression system. The results show that the LIPCA can effectively suppress free vibration of the aluminum beam, compared to the bare PZT and the 3GE + PZT actuator. The experiment confirms that the LIPCA can be used as an actuator to suppress vibration of dynamic structures.

Behavior of Lightweight Piezoceramic Composite Actuator under Compressive Load

In this work, behavior of a unimorph piezoceramic actuator, LIPCA (Lightweight Piezo- Composite Actuator) has been numerically and experimentally investigated. By measuring the lateral displacement created by the compressive load, the buckling load of the LIPCA was determined. Under simply supported configuration, the measured buckling load agreed well with the geometrically nonlinear buckling load from the finite element analysis. The measured data shows that the lateral displacement of the LIPCA is significantly increased when the electric field is prescribed to the LIPCA in addition to the compressive load. The measured data was compared with the computed results from the geometrically nonlinear finite element analysis. The numerical simulation agreed well with the measurement for low compressive load and low electric field.

A Novel PDMS Valveless Micropump with a Circular Lightweight Piezo-Composite Actuator

This paper presents a design and performance evaluation of a valveless micropump fabricated from polydimethylsiloxane (PDMS) based on molding techniques. A circular lightweight piezo-composite actuator (LIPCA) was successfully developed for the actuating diaphragm of the micropump. The LIPCA is a composite actuator designed and fabricated with piezoceramics in combination with carbon fabric and glass epoxy. Numerical and experimental methods were used to investigate the performance of the circular LIPCA. The LIPCA was glued to a PDMS membrane to form the diaphragm of the micropump. The diaphragm has several advantages, such as high displacement, dome-shaped deformation and geometrically independent actuation profile. The diaphragm based on a LIPCA 9 mm in diameter produces a deflection of 27 μm at the applied voltage of ± 200 V and a frequency of 1 Hz. The micropump has a maximum water flow rate of 0.95 ml/min and a maximum backpressure of 3.8 kPa. The merits of the present micropump are low cost, ease of manufacturing and high level of effectiveness. The proposed LIPCA is proven to be a promising alternative to the conventional piezoelectric actuator used in micropumps.

Mechanical Design of Biomimetic Fish Robot Using LIPCA as Artificial Muscle

This paper presents a mechanical design of biomimetic fish robot using the Lightweight Piezo-Composite Actuator (LIPCA). We have designed a mechanism for converting actuation of the LIPCA into caudal fin movement. The linkage mechanism consists of rack-pinion and four-bar linkage systems. Two kinds of caudal fins are fabricated such that the shapes resemble subcarangiform and ostraciiform caudal fin shape, respectively, and then attached to the linkage system. The swimming test using 300 Vpp input with 1 Hz to 3 Hz frequency was conducted to investigate the effect of tail beat frequency and shape of caudal fin on the swimming speed. The maximum swimming speed was reached when the device was operated at its natural swimming frequency. At the natural swimming frequency of 1.016 Hz, maximum swimming speeds were 1.267 cm/s and 1.041 cm/s for ostraciiform and subcarangiform caudal fin, respectively. The Strouhal numbers, which are a measure of thrust efficiency, were also calculated in order to examine thrust performance of the present biomimetic fish robot.