Papers by Keyword: Piezoelectric Actuator

Abstract: The fracture performance of cracked structures is dominated by singular stress in the crack tip vicinity. In fracture mechanics most interest is focused on stress intensity factors, which describe the singular stress field ahead of a crack tip and govern fracture of structures when a critical stress intensity factor is reached. In the present work linear fracture mechanics is applied in order to obtain the fracture toughness parameters of a cracked plate integrated with piezoelectric actuator under mode I loading. Analytical model was derived to represent the relation between piezoelectric parameters and stress intensity factor and energy release rate. The results indicate that the stress intensity factor decreases linearly with the application of the different piezoelectric actuator voltages.

Abstract: In future, demand on portable electronic devices will create the requirements of enduring recharged sources of power. A non-environmental friendly conventional battery with limited lifetimes has no longer feasible option. One of the mostly used solution is the piezoelectric composite structure with sensing and also actuating capabilities, mainly as a MEMS device. The optimum between actuating and energy harvesting functions is difficult to obtain. The article is presenting a study regarding the posibility to optimize both functions, performed using an analytical model and also by simulation using a FEA model.

Abstract: Loading drops with discrete objects, such as particles and cells, is often necessary when performing chemical and biological assays in microfluidic devices. The vast majority of reported encapsulating methods of particles into monodisperse picolitre droplets are based on micro-fluidic chip using the standard soft lithography technique are necessary. This paper presents a new approach, not based on micro-fluidic chip, for encapsulating particles into droplets actuated by microfluidic pulse inertia force. The polystyrene bead suspension can be ejected out of a tapered glass capillary in mineral oil drop by drop actuated by an enough pulse inertia force which is produced by a hollow PZT stack. The polystyrene beads will be randomly encapsulated in monodisperse picolitre droplets. The tapered glass capillary has the advantages of good chemical resistance, low friction, easy to manufacture and low cost and is suitable for chemical and biological analysis. The minimum size of the spherical droplets can reach 12 μm in diameter and about 1 picolitre in volume. The percentage of the droplets with single 5 μm-diameter polystyrene bead can reach 40% when the droplet size is 40 μm and the concentration of the bead suspension is 1×10⁷ beads per milliliter. The experiment result can be applied in droplet-based single cell encapsulating and analyzing.

Abstract: Piezoelectric actuator (PEA) is widely applied in micro/nanopositioning system. However, its inherent hysteresis limits its application. Modeling of hysteresis plays an important role in solving this problem. Linear play operators (LPO) adaptive hysteresis model is introduced in this paper. LPO operators are used to replace delay operators of adaptive transversal filter to compose a new serial structure of adaptive transversal filter model, and LMS (Least Mean Square) algorithm is used to adjust the weight values. As hysteresis loop of piezoelectric actuator is asymmetric and LPO operator is symmetric, a modified LPO (MLPO) adaptive filter is proposed for asymmetric hysteresis effect. At last, the two LPO filters are applied to model hysteresis characteristic of Piezoelectric actuator, and the modeling effect is verified via a micro-positioning system experiment platform based on Piezoelectric actuator. Experimental results show that the modified LPO filters can achieve better accurate hysteresis modeling.

Abstract: An active control test is done trying to control the vibration of gun tube. A four-layer piezoelectric actuator is glued on the root of an analogue tube (a steel barrel) and a voltage amplifier is used to regulate the voltage on the actuator restraining vibration of the barrel. With 130 voltages, the vibration acceleration of the simulated free end of the barrel decreases 83 percent from the original 60 m/s² and he attenuation time is shorted greatly. It can be seen that the vibration of the barrel is decreased obviously. It is feasible and very effective to control the vibration of gun tube by using intelligent structure according to the result of the theoretical analysis and test result.

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As the sensing element and a driving element for vibration control using smart materials, the structural vibration control is very active field for research and application. This paper mainly study the characteristics of piezoelectric self-sensing vibration .Through the action analysis of research on Piezoelectric Actuator establish a self-sensing piezoelectric vibration damper and a model of self-sensing piezoelectric absorber . Then through the experiment and simulation, get the study on its characteristics.

Abstract: Recent years have faced a very modern trend for space exploration activities – constructing, launching and operating nanosatellites have become very popular. One of the major problems of implementing and taking control over the nanosatellite is ensuring accurate but simple and small dimension equipment for attitude control. Most of the equipment implemented for the introduced task was large and bulky in the past and could be hardly used on extremely small satellites. The paper describes equipment under development for attitude control over satellites. Equipment relies on the implementation of piezoelectric transducers for the rotation of a spherical body, i.e. reaction sphere, thus ensuring precise three-axis attitude control over the satellite by means of a single device. Further, the article focuses on the device under development with some calculations and examples of implementing such instruments.

Abstract: Piezoelectric actuators are widely used for the nano/micro positioning and adjustment systems. In the paper, the investigation on the oscillations of contacting surfaces of the piezoelectric thick-walled cylinder is presented. Piezoelectric cylinder is the main component of piezomechanical system named as piezo-screw and is used to turn the screw. This investigated piezomechanical system can be used for the precise positioning with a high resolution (less than 50 nanometers). Piezoelectric cylinder has radial polarization. Traveling-wave oscillations of the second circumferential modal shape (n = 2, m = 1) are excited. Three different electrode topologies are used to drive the screw. Electrodes are grouped into upper and low groups in both topology cases. Each group consists of six electrodes where positions of corresponding electrodes in upper and lower group are shifted by π/6. Numerical investigation of the traveling wave oscillation is performed and dependencies oscillation trajectories of contact surfaces on excitation schemes are determined when three different electrode topologies are used. Dependency of oscillations of contacting points upon length of the actuator is analyzed as well. Advantages and disadvantages of each excitation case are discussed.

Abstract: The electrostatic field distribution of interdigitated electrode piezoceramics (IDEPZT) and piezoelectric fiber composite (IDEPFC) are analyzed by finite element method separately. The impact of the interdigitated electrode asymmetry on the actuation performance of piezoelectric actuators with a certain interlayer thickness is studied. The influence of the interdigitated electrode asymmetry on the actuation performance, stress concentration and electrostatic field concentration with different interlayer thicknesses are also discussed and compared. For piezoceramics, the results show that the actuation performance can be influenced little by increasing the degree of the excursion with a relatively thin interlayer thickness. As the interlayer thickness increases, the actuation performance can be influenced much by increasing the degree of the asymmetry. And it results in the decrease of the longitudinal free strain overall. The electric field becomes increasingly uneven as the degree of the asymmetry increases. The actuated stress can be improved evidently by increasing the degree of the asymmetry with a relatively thin interlayer thickness while the stress concentration is not increased apparently.

Abstract: In order to improve the positioning resolution of the tool adapter on ultra-precision machine tool for KDP crystals, this paper presents a new piezo tool actuator. First, a new flexible membrane structure is designed after considering the characteristics of the machine tool for KDP crystals. Then, its detailed structural dimension is determined by finite element method. Finally, the piezo tool actuator is machined based on designs and its performance data is obtained by experiments. Experimental results indicate that its positioning resolution is superior to 0.5μm and its stroke reaches 4.7μm, which can meet the requirements of ultra-precision machine tool for KDP crystals.