Method Of Physical Focusing Ultrasonic Transducer And Its Detection System

With the development of electronic technology and automation technology, ultrasonic testing technology has the characteristics of image, automation, digital, intelligent, and strong penetration. It has become an important research field of modern detection technology. Ultrasonic transducer(also called probe) is an important part of ultrasonic testing system. By the Shannon formula, the maximum information capacity of ultrasonic transmission is related to the channel transmission bandwidth and channel signal to noise ratio of ultrasonic transducers. If the ultrasonic transducer has a wide band and a good signal to noise ratio, it can obtain the maximum information capacity, but the present ultrasonic transducer has emission excitation time short, narrow band signal, echo signal small, resulting in information transmission capacity is small, the detection performance is not high.Therefore, by studying the spatial distribution characteristics of the common ultrasonic transducer and nonlinear acoustic field characteristics of a physical focusing in a particular probe vessel, a method based on physical focusing is proposed, which can make the local pressure at the end of transmitter become larger, the energy of the probe can be concentrated, and the detection accuracy can be improved. The main work of this paper is as follows:1. According to depth study of the common ultrasonic transducer working principle, the theoretical research which includes spatial distribution of sound field and directivity characteristic of sound beam in the single crystal disc sound source, single crystal rectangular sound source and phased array sound source was built. Then, the phenomenon of their sound pressure space distribution and sound beam directivity are simulated.Last, the spatial distribution characteristics of sound pressure and the performance of sound beam focusing and beam deflection are summarized.2. In order to study the sound pressure distribution in the detector model, a theoretical study on the spatial distribution characteristics of the nonlinear sound field is carried out. Therefore, a method of ultrasonic transducer based on physical focusing is proposed, which can overcome the shortage of direct probe, improve the local sound pressure on the basis of maintaining the probe’s transmitting power and ensuring the minimum total radiation dose, which can reduce the detection range and improve the detection accuracy. At the same time, combined with the principle of communication system, the composition and working principle of the ultrasonic testing system are studied in detail.3. Characteristic data in acoustic field of a physical focusing ultrasonic transducer is analyzed, using software of PZFLex by finite element method.Furthermore, different parameters of the transducer are set up to study the effect of beam focusing with different taper and different position.4. Three kinds of estimation of physical focus detection algorithm of response system’s channel frequency response characteristics are researched deeply. The physical focused ultrasound transducer in the actual environment of frequency response characteristic is tested and its operability in actual application is proved.