Concrete Ultrasonic Nondestructive Testing Tomography Study

As an advanced detection method, ultrasonic nondestructive testing computerized tomography (CT) technology is used to detect inner quality of concrete structure. To acquire clearly and accurately inner structure image of concrete, the system and image reconstruction arithmetic about Ultrasonic-Tomography system used for concrete structure nondestructive testing are studied and improved separately.A new ultrasonic tomography system used for concrete structure nondestructive detecting is designed in the thesis. The new system uses a specially designed high power and short pulse ultrasonic emitter, and can be used to detect great bulk concrete structure in large-scale project. There are 24 channels in the new system to synchronously acquire data, thus, the work efficiency and the position precision of sampling are improved greatly. The improved image reconstruction arithmetic is used in the new system, which improves the speed and precision of image reconstruction.Based on the traditional image reconstruction arithmetic, the thesis presents two improved image reconstruction arithmetic, one is improved arithmetic on algebraic reconstruction technology (IART) arithmetic; the other is tower ART arithmetic. The following conclusions about the improved image reconstruction arithmetic are drawn and verified further through numerical simulations and experiments. First, the IART arithmetic is excellent in back analysis precision, and is good at image reconstruction; second, the speed of the tower arithmetic is very high; third, the both arithmetic fit CT based on ray theory. The correctness and validity of improved arithmetic are validated in project practice.The thesis uses the linear travel time interpolation (LTI) ray tracing arithmetic to trace curve path caused by refraction and diffraction of ultrasonic. Numerical simulations and experiments show that the speed and quality of image reconstruction are improved due to the application of LTI.