Naslov
DETECTION OF MATERIAL ANOMALIES BASED ON INFRARED THERMOGRAPHY IMAGE PROCESSING

Autori
Garafulić, Endri ; Krstulović-Opara, Lovre ; Domazet, Željko

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
NDT week in Zagreb / Krstelj, Vjera - Zagreb : Croatian Society of Non Destructive Testing, 2013, 3-13

Skup
Matest & Certification 2013

Mjesto i datum
Zagreb, Hrvatska, 07.10.2013. - 12.10.2013

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
active infrared thermography; glass reinforced polymer; NDT

Sažetak
Glass rureinforced polymers (GRP) are widely used materials for laitweight structures such as airplanes, glider planes, wind turbine blades, sailing/power boats, vehicles, etc. Infrared thermography as a nondestructive testing method (NDT) is becoming a standard in airplane production industries, where structures made of carbon reinforced polymer (CRP) and GRP are tested during production process and periodically controlled in use. Methods such as passive thermography (often used for after-landing inspection of delamination), transient thermography (hot blanket transient check) and active thermography are common. Active thermography methods such as puled thermography (PT), pulsed phase thermography (PPT) and lock-in termography (LT) are all based on capturing the structure’s thermal response after heat wave propagation. In this presentation we have focused on image processing methods as they play key role in successful detection. The PT is based on analyzing the first frame of cooling after a heat source is removed. In our previous work we have developed a reliable gradient based image processing approach. The approach enables better visualization of anomalies and eliminates the influence of unequal heating. In this presentation we are introducing and comparing image processing based on Daubechies wavelets. The method enables much stronger thermal contrast from gradient approach. The PPT is based on analyzing several hundreds of frames during cooling process. The resulting phasegrams enable locating the anomalies that were not detectable by PT methods. Image processing using fast Fourier and discrete wavelet transforms are compared. The wavelet based method showed to be more powerful and robust. To compere two PT and two PPT methods, a test specimen of vacuum treated GRP with machined blind holes and grooves is used. On practical example of damaged wind blade turbine, the benefits of various approaches are demonstrated.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

POVEZANOST RADA