Development of piezoceramic electroacoustic transducers for acoustic devices with a sound pressure of 125 dB or more

The increased sound pressure level of piezoceramic electroacoustic transducers is important for acoustic devices designed to create high-intensity sound, 125 decibels or more. This is especially true of acoustic devices that use a group of transducers. An electroacoustic transducer that develops a higher sound pressure can greatly reduce the number of radiating elements in an acoustic device. In the performed work electroacoustic transducers are created that capable to develop sound pressure level up to 125 dB. The article presents the results of the development of electroacoustic transducers for three frequency versions. The scheme of the generator of the exciting voltage for electroacoustic converters with the raised sound pressure is offered and investigated. The result is particularly relevant when used in multi-element sound-emitting devices, as repeatedly reduces the required number of converters to achieve the same result.

Ultrasonic Energy Characteristics of ZnO Piezoelectric Thin Films Array Based on MEMS

The characteristics of the ultrasonic energy transference system with MEMS ZnO square piezoelectric thin films array (SPTFA) structure has been investigated in the article. Design principle of the system has been introduced, and the ultrasonic directivity has been enhanced by the films array structure. The silicon panel with the SPTFA structure has been successfully fabricated based on MEMS technology. The ultrasonic energy transference experiment has been carried out as well in order to check the capability of the system by means of two SPTFA panel. Experiment results show that the maximum power density is 2.581mW/cm2 when the amplitude of exciting voltage is 10V, and the light emitting diode is lightened successfully by the system in a distance of 3mm.

Effect of Structure Parameters on Dynamic Characteristics of Piezoelectric Vibrator in Ultrasonic EDM Processing

A piezoelectric vibrator in ultrasonic EDM processing is designed and fabricated. The structure parameters of the vibrator have a very significant impact on the dynamic characteristics. The effect of different structural parameters on dynamic characteristics of the vibrator is analyzed by using Finite Element Method(FEM), and the modal frequency and vibration amplitude sensitivities of the vibrator to the structural parameters are investigated by modal and harmonic analysis.. According the results of the sensitivities analysis, the structural parameters which have an important impact on the working modal frequency and the vibration amplitude are achieved. The vibrator is designed and made based on the above theoretical analysis. The dynamic characteristics of the piezoelectric vibrator are tested. In the case of exciting voltage of 100V (peak-peak value), the first-order longitudinal vibration frequency (working frequency) of the vibrator is 27.36 kHz, vibration amplitude is about9.8μm, which is in compliance with the theoretically analytical results.

Optimal Design of an in-Plane Traveling Wave Rotary Ultrasonic Motor Excited by Single Composite Transducer

This paper presents an optimal design for an in-plane traveling wave rotary ultrasonic motor with a composite transducer. The structure of the stator was improved to minimize negative influence on vibration modes from the supporter, and a new stator based on it was designed and fabricated. Two operating modal frequencies of new stator have been adjusted to equality by reducing one structural parameter according to sensitivity analysis. The performance experiments of the prototype motor shows that maximum no-load speed is 450rpm and maximum torque achieves 0.04Nm at an exciting voltage of 200Vrms.

Grain refinement effect of pulsed magnetic field on solidified microstructure of superalloy IN718

The refinement mechanism of pulsed magnetic field (PMF) was discussed by experimental investigation, and the effects of exciting frequency, exciting voltage, and delay time of PMF on grains refinement of superalloy were studied. The experimental results show that, as exciting frequency or exciting voltage is increased, the grains are refined. However, the grains become coarse when frequency increases further. As delay time of PMF increases, the grain size increases. The refinement effect of PMF is attributed to the detachment of heterogeneous nuclei on the mold wall and subsequently separation of nuclei in the melt. The Joule heat can prolong the continuous nucleation process. However, the refinement effect will be impaired if the Joule heat is strong enough to remelt the detached nuclei.

Forced Response of Electromechanical Integrated Electrostatic Harmonic Drive to Voltage Excitation

In this paper, a micro electromechanical integrated electrostatic harmonic drive system is presented. The operating principle of the MEMS is introduced. The exciting electric field force under exciting voltage is given. Based on the electromechanical coupled dynamic equations of the drive system, by generalized force and generalized coordinate, the forced response of the drive system to voltage excitation are obtained. The forced frequency responses of the drive system to voltage excitation are investigated. Changes of the frequency response along with the system parameters are given as well.