Dalius Mazeika

Optimal Electrodes Configuration of Piezodrives

This paper presents a study of optimisation of the electrodes dislocation of piezodrives. The following conditions of optimisation problem are considered: to unify excitation voltage forms, to achieve reverse motion and maximum coefficient of efficiency. Realisation of this requirement means that current source has to generate voltage of constant frequency, amplitude and phase, reverse motion must be achieved only through changing the polarity of the current source and that the surface of the piezodrive is fully covered with electrodes. FEM modelling is performed in calculating process. The results of calculations for the piezoelectric drive are shown for two options of fixing conditions.

Minimizing heat generation in a piezoelectric Langevin transducer

High power Langevin piezoelectric transducers have large dielectric and piezoelectric losses. Most of these losses are converted into accumulating internal heat that increases the temperature of the transducer. In this paper we analyze how to minimize heat generation and reduce temperature of the transducer. The modification of transducer design is proposed by separating piezoceramic elements and adding a metal block between the elements. Analytical and numerical modeling of the Langevin transducer was carried out to find the dependence of the oscillation amplitudes and temperatures on the location of the separated piezoceramic elements and thermal properties of the additional metal part. Two prototypes of the Langevin transducer with two different locations of the piezoceramic elements were fabricated. Measurements of the vibration amplitudes of the contact point and temperature distribution along the transducers were done. Measurement results are compared with the numerical results.

Development of Traveling Wave Actuators Using Waveguides of Different Geometrical Forms

The paper covers the research and development of piezoelectric traveling wave actuators using different types of the waveguides. The introduced piezoelectric actuators can be characterized by specific areas of application, different resolution, and torque. All presented actuators are ultrasonic resonant devices and they were developed to increase amplitudes of the traveling wave oscillations of the contact surface. Three different waveguides are introduced, that is, symmetrical, asymmetrical, and cone type waveguide. A piezoelectric ring with the sectioned electrodes is used to excite traveling wave oscillations for all actuators. Operating principle, electrode pattern, and excitation regimes of piezoelectric actuators are described. A numerical modelling of the actuators was performed to validate the operating principle and to calculate trajectories of the contact points motion. Prototype actuators were made and experimental study was performed. The results of numerical and experimental analysis are discussed.

Miniature flat type inertial piezoelectric motor

Study of a novel design miniature linear piezoelectric motor is proposed in the paper. Size of the motor not exceeds 150 mm3. Piezoelectric motor consists of “butterfly” type actuator and slider. Elliptical trajectory of the actuator is achieved using bending oscillations of the plates of actuator when harmonic or short impulse type excitation is used. Contact zone trajectory of motion is analyzed for both type of excitation. Advantages of impulse type excitation are simpler electric circuit scheme, lesser dependence between the rotor torque and excitation frequency. It allows increasing torque of the rotor without increasing dimensions and mass of the actuator. Numerical modeling of the piezoelectric motor was done to analyze natural frequencies, modal shapes of the actuator and to examine actuator response to the harmonic and impulse type excitation. Experimental prototype of the piezoelectric motor was built and measurement contact zone motion was done. Results of numerical and experimental studies are discussed.

Adaptive Resource Provisioning and Auto-scaling for Cloud Native Software

Cloud-native applications (CNA) are developed to run on the cloud in a way that enables them to fully exploit the cloud computing characteristics. These applications are strongly dependent on automated machinery (i.e. auto-scaling engines, schedulers and cloud resource provisioning software), which enables elasticity and auto-healing. These features improve application availability, resource utilization efficiency and help minimizing SLA violations related to performance. This work provides a generic architecture of software system that enables elasticity of cloud native software by use of automated scaling and resource provisioning. The architecture is based on analysis of previous works presented by practitioners and academia. Also it is a cloud platform and vendor agnostic.

Piezoelectric Actuator Based on Two Bending-Type Langevin Transducers

Abstract Langevin-type piezoelectric transducers are widely used for different industrial applications such as high-accuracy positioning, ultrasonic welding, bonding, drilling, etc. Usually Langevin-type transducers operate at longitudinal mode by employing d33 vibrations of piezoceramic elements. A novel design of piezoelectric actuator based on two bending-type Langevin transducers is introduced. Two half-wavelength transducers are connected by a special aluminum plate. Piezoceramic rings with two-directional polarizations are used for bending oscillation excitation. An input voltage with phase shifted by π/2 on different transducers is applied. The forward and backward elliptical motion of the contact tip is controlled by changing phases of electric signals on different transducers. A numerical simulation was carried out to investigate the trajectories of contact point motion and to validate the operating principle of the actuator. Experimental prototype of the piezoelectric actuator was fabricated, and the measurements of driven tip movements and mechanical output were performed. The results of numerical and experimental analysis are discussed.

Multi-DOF cylindrical piezoelectric actuator with radial polarization

The paper presents the results of numerical and experimental investigation of cylindrical piezoelectric actuator used for achieving independent three degrees of freedom oscillations of the contact point. The design of actuator based on a hollow piezoelectric cylinder mounted on a metal rod. The piezoceramic cylinder has a radial polarization and special configuration of the electrodes that cover inner and outer surface of the cylinder. The main advantage of actuators design is that solid metallic rod operates as a part of inner electrode of the cylinder and a stator of actuator. The geometry of piezoelectric actuator was adopted to reach resonance of oscillations for the first longitudinal mode and the third flexural mode at same frequency. The actuator is designed to move positioned object through contact point which is located on the top of the rod. The optimal topology of electrodes was found to achieve longitudinal and flexural oscillations of the actuator in two perpendicular planes. Three degrees of freedom of the positioning object can be achieved and control of the system can be implemented by applying different excitation schemes and regimes. The numerical simulation and experimental study of piezoelectric actuator was performed. Impedance of actuator was analyzed under different excitation regimes. The results of numerical modeling and experimental study were compared. Recommendations for the further development of this type of actuator are given.

Investigation of Contact Point Trajectories of Piezoelectric Actuator with Bidirectional Polarization

Contact point trajectories of the beam type, quadratic cross-sectional piezoelectric actuator with non-uniform polarization are analyzed in the paper. Polarization vectors of the actuator have perpendicular directions on the first and second half of the actuator. Bidirectional polarization is used to achieve flexural oscillations of the actuator in perpendicular planes and to increase the number of degree of freedom of the contact point movement. A particular electrode pattern of the actuator was found and contact point trajectories are analyzed under different excitation regimes. Prototype piezoelectric actuator was build and experimental measurements of contact point trajectories were performed. The results of numerical modeling and experimental study are compared and discussed.