Full matrix focusing method of ultrasonic phased array has been proved with advantages of good signal-to-noise ratio and imaging resolution in the field of Ultrasonic NDT. However, it is still suffering from the time-consuming data acquisition and processing. In order to solve the problem, two simplified matrix focusing methods are provided in the paper. One provided method is a triangular matrix focusing algorithm based on the principle of reciprocity for the multi-channel ultrasonic system. The other provided method is a trapezoidal matrix focusing algorithm based on the energy weight of the different channel to the focusing area. Time of data acquisition and computational is decreased with the provided simplified matrix focusing methods. In order to prove the validity of two provided algorithms, both side-drilled holes and oblique cracks are used for imaging experiments. The experimental results show that the imaging quality of the triangular matrix focusing algorithm is basically consistent to that of the full matrix focusing method. And imaging quality of the trapezoidal matrix focusing algorithm is slightly reduced with the amount of multi-channel data decreasing. Both data acquisition and computational efficiency using the triangular matrix focusing algorithm and the trapezoidal matrix focusing algorithm have been improved significantly compared with original full matrix focusing method.

Large time-bandwidth product coded signal and pulse compression in radar field have been introduced into ultrasonic testing. Linear frequency modulation (LFM), a frequency coded signal, is usually used to improve the time resolution, but the sidelobe of LFM should be suppressed to detect smaller flaws nearby. Barker coded signal of length 13, a binary phase coded signal, is usually used to suppress the sidelobe, but the wave width of results is larger than LFM. So a frequency-phase coded excitation is proposed to obtain good testing results with higher time resolution and lower sidelobe of. It combines the frequency and phase coded signal. LFM is applied to each subpulse of Barker code, and it is called LFM-B 13. The simulations are carried out using K-wave toolbox in Matlab. The results of simulations demonstrate that, when using LFM-B 13 excitation, the main sidelobe level is suppressed better and the time resolution is improved higher than using LFM excitation. The time resolution of LFM-B 13 excitation is approximately 40% higher than that of LFM excitation, and the sidelobe of LFM-B 13 excitation is approximately 4 dB lower than that of LFM excitation, when 60% bandwidth of 5 MHz central frequency transducers are used in penetrating experiments' simulations.