The Utility of Numerical Methods in NDE

When applied with physically meaningful inputs that have been guided by analytical analysis, numerical modeling is a quick and cost-effective virtual experiment that has the added benefit of being free of experimental error. Furthermore, with the rapidly evolving processing power of modern computers, highly complex structures and physical phenomena can be modeled with relative ease. This paper discusses the application of semi-analytical and fully numerical modeling methods as employed for the study of ultrasonic techniques in complex structures and materials. A brief review of these two numerical modeling approaches is presented followed by several practical examples that highlight the utility of each technique. One example presented includes the simulation of the ultrasonic field created in a dissimilar metal weld by a linear phased array transducer. A second example presented includes the three-dimensional modeling of guided wave propagation through elbow fittings in a pipe. Finally, a metrological process for the translation of real, geometrically complex components into the modeling environment is presented and the modeled response from fatigue cracking in a thick walled carbon steel turbine shell is compared with the actual defect response.