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

Erik Lindgren (Institutionen för material- och tillverkningsteknik, Avancerad oförstörande provning)
EURASIP Journal on Advances in Signal Processing (1687-6180). Vol. 2014 (2014), p. 9.
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: Radiography, Nondestructive evaluation, Chain porosities, Laser welding, Image analysis, Multiple hypothesis tracker



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Denna post skapades 2014-01-27. Senast ändrad 2015-04-20.
CPL Pubid: 193091

 

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