Simply Supported Boundary Bending Vibration Ladder Disc Sound Field Calculation

Power ultrasound mainly researches high-power or high-intensity sound generating system, sound's mechanism to material and a variety of ultrasonic processing techniques and applications. With the development of ultrasonic technology, the applications of strong-power sound waves in the air become more extensive, Such as acoustic levitation, acoustic dry ,the dust clearance with acoustic waves, ultrasonic level measurement, etc. In order to produce and propagate power sound in the air, the main problem is the low impedance of air medium and high absorption. This requires radiator with high efficiency and good directivity can achieve good impedance matching with air.A longitudinal transducer and front-end sheet metal composite transducer, due to a combination of vertical and efficient high-power transducer, as well as sheet metal bending vibration of the low impedance and radiation characteristics of the area, strong in the air field of power ultrasound was widely used. This longitudinal transducer and flat-panel composite disc transducer has a wide range of applications in the actual production, However, when the disc does a pitch or number of vibrations, due to pitch on both sides of the vibration phase contrast, the sound field generated interference cancellation, partly offsets ultrasonic energy and reduces efficiency by radiation.In order to improve radiation efficiency, radiation circular plate's surface can be modified the form of the ladder, and its step height equal to the radiation medium 1 / 2 wavelength, it can avoid the phase-contrast interference cancellation to improve the radiation efficiency. In the sixties and seventies of last century, Spain Gallego scholars first proposed using composite bending vibration transducer, that consists of disc-shaped radiator, ladder-shaped horn and piezoelectric sandwich transducer component. The disc's vibration is from the disc center. Horn excitation generated in the disc surface vibration system for the acoustic radiation into the air to provide a good mechanical impedance matching and thus improve transducer electro-acoustic conversion efficiency.This article on such front-end sheet metal radiator ladder for simply supported circular plate when the vibration of the case study and its design, innovation and research results mainly in the following areas:Study calculated the bending of simply supported boundary conditions the frequency of vibration ladder disc equation: different boundary conditions on the ladder plate bending vibration frequency of the impact is different in the thin plate theory, based on the numerical method used to solve a programming and two sections of the simply supported circular plate the frequency of the ladder equation. At the same time, give a simply supported disc ladder directional sound field calculation method, and draw a point of Fig.Simply supported stepped plate finite element simulation: in order to verify the accuracy of numerical calculation using the finite element simulation software ANSYS, a simulation of the vibration mode ladder disc distribution, obtained a ladder on the particle diameter disc displacement, intuitively ladder disc showing the location of the pitch circle.On the ladder with a horn radiator disc were studied: Luffing's resonant frequency of the ladder with a single disc and the fundamental frequency horn is different from the horn and stepped into the disc horns , we must consider the mutual influence between the two. Design and calculation of a conical horn, and then with the ladder horn disc through the combination of different ways, through the finite element simulation to identify deficiencies; and then optimize the portfolio approach, have better results.The results of the analysis of the study has a certain reference value to the use of such radiator to improve the application of ultrasound in the efficiency of the air.