Non-destructive transmission tomography

Based on theoretical analysis, a new method of transmission tomography of surface defects of pipelines using ultrasonic waves propagating along their walls is proposed. The waves are excited and received by sensors on two ring-shaped lines spaced along the top of the tube. These waves, spreading over the surface of the pipe, are rectilinear cylindrical waves that twist either to the left or to the right along the pipe like torsion waves. When a defect appears on the surface, the resulting waves are accompanied by changes in the thermal projections at the controlled end of the pipe. The problem of defect tomography is to determine the location and shape of defects by reversing the resulting projections. The physical feature of this problem from traditional tomography is that all these projections occur on mutually intersecting and left and right trajectories. The solution of the problem is achieved by repeated transverse prolongation of the forming cylindrical surface of the tube, on which all wave paths become straight. The paper provides a number of examples that confirm the possibility of restoring the proposed method of location and shape of defects of various shapes.

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