Traditional ultrasonic TOFD （ time of flight diffraction） has the major shortcoming of low amplitude of diffractive wave which brings about lack of sensitivity for weld defect detection. Aimed at the technological l...Traditional ultrasonic TOFD （ time of flight diffraction） has the major shortcoming of low amplitude of diffractive wave which brings about lack of sensitivity for weld defect detection. Aimed at the technological limitation, a novel TOFD method is proposed by developing a focusing probe. Through the analyses and calculation of sound field distribution based on geometric acoustics, a cylindrical surface wedge is designed and produced. Artificial defect containing testing piece is made and tested using both traditional and focusing TOFD, and the received signal and image are compared. The result shows that the proposed focusing method can converge the emitted sound energy effectively and improve testing sensitivity greatly. Compared with traditional TOFD tested data, focusing TOFD tested defect wave in A-scan line and defect diffractive stripe in D-scan image can be identified easily.展开更多
The traditional one-dimensional ultrasonic beam steering has time delay and is thus a complicated problem. A numerical model of ultrasonic beam steering using Neumann boundary condition in multiplysics is presented in...The traditional one-dimensional ultrasonic beam steering has time delay and is thus a complicated problem. A numerical model of ultrasonic beam steering using Neumann boundary condition in multiplysics is presented in the present paper. This model is based on the discrete wave number method that has been proved theoretically to satisfy the continuous conditions. The propagating angle of novel model is a function of the distance instead of the time domain. The propagating wave fronts at desired angles are simulated with the single line sources for plane wave. The result indicates that any beam angle can be steered by discrete line elements resources without any time delay.展开更多
基金Supported by the International Cooperation Project （2007DFR70070）, the National Natural Science Foundation of China （51005056, 50775054） and the Research Fund for the Doctoral Program of Higher Education （20102302120045 ）.
文摘Traditional ultrasonic TOFD （ time of flight diffraction） has the major shortcoming of low amplitude of diffractive wave which brings about lack of sensitivity for weld defect detection. Aimed at the technological limitation, a novel TOFD method is proposed by developing a focusing probe. Through the analyses and calculation of sound field distribution based on geometric acoustics, a cylindrical surface wedge is designed and produced. Artificial defect containing testing piece is made and tested using both traditional and focusing TOFD, and the received signal and image are compared. The result shows that the proposed focusing method can converge the emitted sound energy effectively and improve testing sensitivity greatly. Compared with traditional TOFD tested data, focusing TOFD tested defect wave in A-scan line and defect diffractive stripe in D-scan image can be identified easily.
基金supported by the National Natural Science Foundation of China (10972014)
文摘The traditional one-dimensional ultrasonic beam steering has time delay and is thus a complicated problem. A numerical model of ultrasonic beam steering using Neumann boundary condition in multiplysics is presented in the present paper. This model is based on the discrete wave number method that has been proved theoretically to satisfy the continuous conditions. The propagating angle of novel model is a function of the distance instead of the time domain. The propagating wave fronts at desired angles are simulated with the single line sources for plane wave. The result indicates that any beam angle can be steered by discrete line elements resources without any time delay.
