Research On Ultrasonic Phased Array Imaging Technology

Ultrasonic phased array testing technology can produce flexible, controllable synthesized sound beams to realize dynamic focusing and high-speed scanning by exciting each element of array with independent phase delay. In recent years, as modern industry diagnostic and testing technology is experiencing fast development toward information and visualization, digital array phased ultrasonic testing technology has been highly recognized in domestic and foreign NDT research domain.This article discusses the phased array ultrasonic testing theory, including the theory of ultrasonic radiation, phased array ultrasonic testing of the theory and testing methods of beam control. Depth analysis of phased array ultrasonic transducer array element pitch, width, number of probe array element properties for the production of high-performance phased-array probe provided a basis. An inversion method named impulse response wave front simulation was suggested based on the dynamic photoelastic experiments. Then the practical forward algorithm of acoustic field in a rod and the scattering acoustic field of a cylinder cavity were obtained. The validity of the forward algorithm was proved by the comparison between the results of the forward simulation and the dynamic photoelatic experimentsA quasi-ultrasonic phased array testing technology is proposed which is somewhat similar to the synthetic aperture focusing method. Real-time dynamic focusing is replaced by data synthetic focusing, getting the same testing information. To be specific, some units are motivated iteratively, and then the ultrasonic full-wave signals received by each unit are recorded in turn by hi-speed data acquisition and treated by software. Detection information of each focusing point can be acquired by adjusting the time delay sequence. Thus, the data processing ability of computers in the time domain is fully displayed, and the digital receiving channels is reduced to only one. The equipment cost is put down greatly, which opens the gate of phased array to the common industry testing.Based on this quasi-ultrasonic phased array testing method, a set of 49-channel experimental system to sample and process the linear phased array ultrasonic signals is developed. The signals emitted and received by the single elements are synthesized according to the wave theory, that is, the numerical signals are synthesized in the time-space domain by a computer. The same testing information as phased array focusing can be obtained. This following can be proved from the experiments done with the system: The intensity of phased array testing signals can be achieved; the SNR is improved greatly; testing sensitivity and resolution are equal to the phased array testing. The testing results conform to the real flaw situation and then the quasi-ultrasonic phased array testing method is verified as a new method of array phased ultrasonic for industry testing.