Comparison between Microwave Infrared Thermography and CO₂ Laser Infrared Thermography in Defect Detection in Applications with CFRP

Sam-Ang Keo, Didier Defer, Florin Breaban, Franck Brachelet

Laboratory of Civil Engineering and GeoEnvironment, PRES Lille Nord of France, Lille, France; Faculty of Applied Sciences, Béthune, France.
Laboratory of Civil Engineering and GeoEnvironment, PRES Lille Nord of France, Lille, France; University Institute of Technology of Bethune, Béthune, France.

DOI: 10.4236/msa.2013.410074                

Abstract

This paper presents two infrared thermography methods with CO₂ Laser excitation and microwave excitation applied to defect detection in CFRP. The tests were conducted with two specimens, one with defect, and another one without defect. On two concrete plates 40 cm× 40 cm× 4.5 cmwere reinforced by CFRP; the defects were made by the absence of adhesive on an area10 cm× 10 cm. The specimens were heated by microwave, generated by a commercial magnetron of 2.45 GHz and guided by a pyramidal horn antenna, with a power of 360 W within 150 s. Another series of the tests was conducted with CO₂ Laser, wavelength 10.6 μm, by heating the samples with a power of 300 W within 40 s. An infrared camera sensitive to medium waves in range of 3 - 5 μm, with a detector of 320 × 256 matrix detector in InSb (Indium Antimonide), was used to record the thermograms. As a result, the CO₂ Laser excitation is better for the delamination detection in CFRP. This study opens interesting perspectives for inspecting other types of defects in materials sciences; the microwave excitation is suitable for the deep defects in the materials whereas the CO₂ Laser excitation is better for the defects near the surface of the materials.

Keywords

CFRP; Defect; Microwave; CO₂ Laser; Infrared Thermography

Conflicts of Interest

The authors declare no conflicts of interest.

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