Mohammad Riahi - Iran University of Science and Technology, Department of mechanical Engineering;
Mohammad R. Khademikhaledi - Iran University of Science and Technology, Department of mechanical Engineering
Ali Valipour - Iran University of Science and Technology, Department of mechanical Engineering;

The Time -Of-Flight Diffraction (TOFD) technique is rapidly gaining importance as a stand-alone inspection technique. TOFD technique is an advanced ultrasonic technique that fulfills the need for reliable inspections. TOFD is routinely used in a wide range of applications such as inspection of piping and pressure vessels. The principle of TOFD technique is based on mapping of the position of the edges of defects. This is in contrast with conventional ultrasonic, which relies on the amplitude of specula reflections received from defects. Defect’s length can be readily measured by subtraction of the depth of lower and higher edges. Like any other technique, TOFD also has its limitations. In this investigation, this technique has been applied to thick sections (> 15 mm). This paper discusses the application of finite element method to simulate the ultrasonic time-of- flight diffraction technique in a two-dimensional geometry. The finite element package ABAQUS was used to model the propagation of ultrasonic waves. This study helps in the design and setup of TOFD testing measurements. Especially when dealing with thin sections and complex geometry, the findings of this study are viable. The simulated results were compared with experimental observations, and found to be in good agreement with each other.

Wave propagation, Time-of-flight Diffraction (TOFD) , Finite element method, Flaw sizing