Ultrasonic Signal Simulation for Thick-Walled Welds Based on Ray-Tracing Algorithm and Ultrasonic Field Calculation

Thick-walled welds are one of the most important components of large structures, which requires effective NDT and NDE techniques. UT technique is commonly used for welds, but does not perform well in thick-walled welds because of the coarse-grained microstructures. This paper introduces an efficient method to simulate ultrasonic signals in thick-walled welds, based on an anisotropic and inhomogeneous weld model in 2D. The method consists of three major steps, including ray-tracing, field calculation and signal simulation. The ray-tracing algorithm is developed based on Ogilvy’s RayTRAIM. The ultrasonic field is calculated along the traced ultrasonic rays using the multi-Gaussian beam model. The simulated defect echoes are generated based on a flaw scattering model, according to the calculated ultrasonic fields. All the algorithms and models have been improved and optimized for higher efficiency, based on the characteristics of the 2D weld model. UT experiments were performed to verify the simulation method. An austenitic weld with four SDHs was inspected using the phased array technique. The simulated defect echoes fit with the experimental signals with acceptable deviations, indicating the validity of the simulation method. Improvement of the method is required in future study, in order to predict the ultrasonic signals more precisely.