Computerized Ultrasonic Raytracing Model for C-scans of Solid Steel Bridge Pins

This report describes the results of computerized ultrasonic C-scanning of solid steel bridge pins using a raytrace model. The raytrace model was developed to facilitate interpretation of data obtained from an ultrasonic C-scanning system for the Virginia Transportation Research Council (VTRC). The report discusses the reasons behind the development of the raytrace model, as well as specifications of the model, the input conditions, and the data output and visualization.

The model uses as input, various "boundary" conditions of the solid steel pin with reduced diameter pin ends, as well as size and location information of a flaw or a wear groove placed within the main pin body. The model considers sound beams to be composed of rays and calculates ray reflections/conversions. This is done until the ray returns to a receiver location or is lost due to exceeding the time-of-flight. Once the model has returned with the received ray data, it uses the receiver conditions provided (transducer used, size of scanning grid, grid resolution, etc.), and calculates a 2-Dimensional C-scan image for each particular depth/time selected. Using PV-Wave visualization software, it is possible to plot the values for each depth to view a color graph. This graphical plot can then be analyzed/compared with the field C-scans to determine the closest match of a flaw or a wear groove inside the bridge pin. This helps in deciding if the condition of the pin is acceptable.