Определение формы объекта в ультразвуковой дефектоскопии с помощью кусочно-линейного представления

Abstract

A new way of representing the shape of an object bottom using non-destructive ultrasonic testing techniques is proposed. The image of the examined object’s bottom is represented by a set of short segments. Each of these segments is a tentative ultrasonic signal reflection place. The segment intersection place is the place at which the ultrasonic signal is reflected. An algorithm for erasing segments that are not a place at which the ultrasonic signal is reflected from the bottom is proposed. This erasing is performed using elementary logic and takes a short time to do. The segments that remain after erasing are the places at which the ultrasonic signal is reflected from the bottom. Since the medium is constant and remains unchanged, it becomes possible to accumulate the obtained echo signals. Owing to this feature, the synthetic aperture method is used. An ultrasonic pitch-catch sensor moving with a constant step is used. Each signal is saved in memory. The total number of steps is N. After obtaining the echo oscillograms, the signals are subjected to processing. It is assumed that strong attenuation of ultrasound is observed in the object being examined, due to which a complex modulated signal is used. Computer-aided simulation was carried out. A new shape of the object bottom is used in each computer model. The proposed method for visualizing the object’s bottom shape is compared with a tomogram. A homogeneous medium with strong damping is used in the computer model. Experiments with a new object bottom shape in each of them are carried out. The tomogram and the proposed method for visualizing the object bottom shape are compared with each other. Water was used in the experiment as the medium. The obtained results have been compared with each other, and conclusions have been drawn. In many cases, the new representation of an object gives a clearer picture.