The invention relates to a dynamic sparse ultrasonic full-focusing method for a large-wall-thickness structural member, belongs to the field of
nondestructive testing, and solves the problems of low full-focusing imaging efficiency, insufficient deep defect detection sensitivity and unbalanced
imaging quality at different depths caused by a fixed sparse rate during
ultrasonic testing of the large-wall-thickness structural member (the thickness is greater than or equal to 300mm) in the prior art. The method comprises the following steps: S1, acquiring medium sound velocity and
total thickness of a detected component and determining array parameters of the detected component; s2, collecting a full-matrix
signal covering a detection depth range; s3, establishing an acoustic beam
diffusion model, and calculating acoustic beam
diffusion widths at different depths; s4, dynamically distributing the
array element sparse rate of each depth; and S5, selecting an effective
array element according to the sparse rate, calculating the
delay time from the effective
array element to the focus point, and reconstructing and imaging to obtain a full-focus detection image covering the whole detection depth. Efficient and accurate
nondestructive testing of large-wall-thickness structural members such as pressure containers and heavy pipelines is achieved, and
imaging quality and detection efficiency are both considered.