Modeling of ultrasonic testing Time of Flight Diffraction (ToFD) technique by Finite Element Method

Time-of-flight diffraction (ToFD) is an ultrasonic nondestructive testing technique used for detection, sizing and location of defects in industrial parts. This method has better abilities and benefits than other nondestructive testing techniques. The advantages of this method are fast speed, low cost, better evaluation of defects without depending on their orientation and high accuracy in measuring defects. This technique is usually applied for thick sections (>15 mm), the application of the ToFD technique to thin sections like pressure vessels and piping requires simulation of this technique. Also doing practical experiments for specification appropriate parameters is very time consuming and expensive. Using simulation, one can perform the experiments with low cost and fast speed. In this paper, the ultrasonic time-of-flight diffraction (ToFD) technique has been modeled in two different parts by using the finite element method (FEM). The explicit solution method of the finite element package ABAQUS is used for solving the propagation problem of ultrasonic waves. Finite element modeling of ToFD technique and in general simulation of ultrasonic wave propagation, has provided a better understanding of the propagation of ultrasonic waves and their interaction with different discontinuities.