Detection, 3-D positioning, and sizing of small pore defects using digital radiography and tracking

Abstract

This article presents an algorithm that handles the detection, positioning, and sizing of submillimeter-sized pores in welds using radiographic inspection and tracking. The possibility to detect, position, and size pores which have a low contrast-to-noise ratio increases the value of the nondestructive evaluation of welds by facilitating fatigue life predictions with lower uncertainty. In this article, a multiple hypothesis tracker with an extended Kalman filter is used to track an unknown number of pore indications in a sequence of radiographs as an object is rotated. Each pore is not required to be detected in all radiographs. In addition, in the tracking step, three-dimensional (3-D) positions of pore defects are calculated. To optimize, set up, and pre-evaluate the algorithm, the article explores a design of experimental approach in combination with synthetic radiographs of titanium laser welds containing pore defects. The pre-evaluation on synthetic radiographs at industrially reasonable contrast-to-noise ratios indicate less than 1% false detection rates at high detection rates and less than 0.1 mm of positioning errors for more than 90% of the pores. A comparison between experimental results of the presented algorithm and a computerized tomography reference measurement shows qualitatively good agreement in the 3-D positions of approximately 0.1-mm diameter pores in 5-mm-thick Ti-6242.

Applications in X-ray Testing

“…In the last few years, some methods based on the tracking principle (as explained in Sect. 8.2.2) have been developed [25,26].…”

Non-Destructive Detection of Real Defects in Polymer Composites by Ultrasonic Testing and Recurrence Analysis

“…Radiography testing using X-rays is a common method for detecting voids, cracks, inclusions and various types of fibre orientation. An important advantage of this method is the ability to detect defects at a level of 50 µm [ 13 ]. Thermographic testing using heat is based on the change in thermal conductivity at the location of the defects.…”

Frequency Optimization for Enhancement of Surface Defect Classification Using the Eddy Current Technique

“…Non-destructive testing (NDT) is an invaluable tool to detect, identify and characterize defects in a component or system without hindering its future usability. Compared to common ultrasonic [ 4 , 5 ] and X-ray [ 6 , 7 ] techniques, eddy current testing (ECT), which operates on the principles of electromagnetic induction, has many advantages such as its efficiency, low cost, noncontact nature, implementation and so on. Currently, ECT has been widely accepted as a desirable technique for characterization of defects in metallic parts [ 8 , 9 , 10 ].…”