Research Of Ray Tracing Methods With Ultrasonic CT And Its Application

As one of the most economical methods of non-destructive test, ultrasoniccomputerized tomography (UCT) can reflect the quality of tested across section in anobject precisely and integrally. So UCT have been a kind of efficient methods ofnon-destructive test method. On the other hand, in the circle of engineering, UCT is atthe beginning of its application stage, and there are still some problems in dataacquisition and data processing that are holding the application of UTC in thenon-destructive testing in engineering. The algorithm for image reconstruction is one of the key techniques forcomputerized tomography (CT). Singular value decomposition (SVD) is widelyaccepted as a kind of right algorithm for ill-conditioned matrix. Numerical simulationsin this paper reveal that simultaneous iterative reconstruction (SIRT) can lead moresatisfactory result than that from SVD when data are gotten at limited observing anglesor data are deficient for processing, because SIRT method can use preexistentinformation. Numerical simulations and tests show that among three ray tracing methods ofstraight ray, 3-point disturbing in rectangle cell and linear traveltime interpolation (LTI),LTI is mostly effective to trace the shortest path, and is suitable for CT to complexobjects; the effect of 3-point disturbing in rectangle cell is in the middle from straightray tracing to LTI. If the variety of wave velocity distribution is not too intense, theanalytical results from 3-point disturbing method and from LTI are almost same, but3-point disturbing method takes less processing time than that LTI takes. At last, numerical simulations and actual projects are calculated to prove the effectof the three ray tracing methods Results show that the effect of image reconstructionbase on bended ray tracing is much better than that on straight ray tracing.