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Analyzing the Influence of Thermal NDT Parameters on Test Performance

Authors :
Joaquim Mendes
A. Silva
Sofia Leite
Mário Vaz
Source :
Russian Journal of Nondestructive Testing. 57:727-737
Publication Year :
2021
Publisher :
Pleiades Publishing Ltd, 2021.

Abstract

Thermography is an imaging technique that uses the infrared radiation to create a thermal image. Due to changes induced in the thermal conductivity of materials, the superficial temperature pattern of a defected component can reveal delamination, voids, insertions, moisture, or changes in material continuity when heated. High power light can be used to produce, without contact, a slight increase in the temperature of the component that creates a specific thermal pattern in the vicinity of a defect. The aim of this work is to analyze the influence of thermal NDT parameters on the performance of composite materials boards with simulated defects test using lock-in thermography, and thus find the optimal parameters that maximizes the signal/noise ratio. Four samples were submitted to 60 thermal tests to evaluate the detectability performance c (defect with/defect depth). The results were processed using custom scripts developed in LabVIEW to crop, scale, and extract the thermal information at the sample' slots and sound areas. The results indicated that the parameter with higher influence is the stimulation duration. The best time to conduct a thermal analysis is also very important, which is usually right after the end of the stimulation in order to have the maximum contrast in the thermal images and to minimize the artifacts. In this work, the defect detectability was between 1.25 and 1.67, which shows an higher sensitivity than reported in previous works (c = 2).

Details

ISSN :
16083385 and 10618309
Volume :
57
Database :
OpenAIRE
Journal :
Russian Journal of Nondestructive Testing
Accession number :
edsair.doi...........b91b729db398566642a37cd42164752d