Investigation On Simulation And Visibility Of Ultrasonic Field Based On MATLAB

Simulation of ultrasonic testing progress becomes a hot issue with the development of ultrasonic testing technology. Ultrasonic sound field has a close relation of detecting the defect, quantifying its size and accuracy and sensitivity of testing, thus understanding the structure and distribution of sound field plays an important role on improving reliablility and efficiency of ultrasonic testing. Round and rectangular piston transducers are the common sound source in ultrasonic nondestructive testing, and combination plane arrays of line and rectangular array are the foundation of investigating phased array technology, so simulating these sound field is significant for studying ultrasonic field simulation.Visualization of scientific computing (called visualization simply), is a new field of Computer Graphics. Visualization includes a series of interactive handling of the theory, methods and techniques which displayed on the screen. Using computer graphics and image processing technology, the data from scientific computing and the corresponding results will be converted into graphic or image. The sound pressure distribution and directivity formulas were deducted based on the sound field model built up by Kirchhoff integral theorem. Sound field of round and rectangular piston transducers were simulated and visualized by M-language of MATLAB. Visual graphics were applied to analyze distribution and directivity, summing up the rule of sound field. A comparison has carried out on the acoustic pressure distributions among the transducers with the diameter of 10 mm, 20mm, 50mm and exciting frequency of 1 MHz, 2MHz, 5MHz, respectively. Increasing size or frequency of the sound source will lead to that the main lobe of beam become narrow, deputy flap become more, acoustic pressure in the axis become larger and the radiation of sound field become smaller. The influence of product of wave number and sound source size on directivity was discussed, and it was found that the sound field become intense, energy become focused and its directivity become better with the increase of product value. A further analysis on the directivity character of radiation sound field of combination plane arrays of line and rectangular array was carried out on the basis of investigating directivity of round and rectangular piston transducers. Distribution and directivity character of M (row)×N (column) 2×2, 3×3, 3×8 array of line combinations plane arrays and M (row)×N (column) 2×2, 2×6 rectangular combination plane arrays were analyzed respectively. It was found that the more array number, the more complex for the distribution. In the direction (a row or column) of the more array number will make sidelobe suppression, the main lobe relatively prominent and energy more concentrated. The influence of liquid/solid interface on sound field distribution has been discussed, taking the water/steel interface for example, and it was found that the acoustic pressure in the solid will increase when the wave propagates from the small acoustic impendence medium to the large one. According to all discussions above, some effective results can be obtained: sound source size and transducer working frequency are the main factors of influencing sound field distribution and its directivity character. Also is the array number and situation. Interface has a great influence on sound field distribution, and its change depends on the value of acoustic impendence and transmission coefficient. Finally, the method in our work was verified by comparing parts of the simulation results in this paper with some previous studies.Nonrepresentational sound field was converted into eyeable images on the basis of simulation and visualization. It is conducive to analyze and comprehend sound field by an image directly. At the same time, it can avoid the complex analytic calculating process so as to reduce the difficulty of investigating the sound field. Sound field simulation and visualization provide a convenient method for analyzing and researching transducer radiation field, and selecting the transducer in various testing situation, signal reception. It is also able to provide the reference for ultrasonic characterization and evaluation, and select manufacturing parameters of transducers.