PSI - Issue 16

Valentyn Uchanin et al. / Procedia Structural Integrity 16 (2019) 198–204 Valentyn Uchanin, Giuseppe Nardoni / Structural Integrity Procedia 00 (2019) 000 – 000

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4. Applications 4.1. Eddy current inspection of gas turbine blades by double differential type EC probe

The fillet areas of gas turbine blade are very critical from the fracture mechanic point of view (Abassi et al. (2008)), Blahnio et al. (2011)). Special double differential type EC probe with long handle was developed for blade inspection. To validate new technology based on new probes application special reference blade with two 0,2 × 0,2 × 4 mm size slits were produced (Fig. 6, left).

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Fig. 6. (left) Reference blade for validation of EC testing with two 0,2 × 0,2 × 4 mm size slots and (right) EC probes during fillet area inspection.

Anyone could see (Fig. 6, right) that the EC probe situated in fillet area has some clearance with inspected surface. But even in this case good enough sensitivity was achieved. Due high lift-of suppression the noise produced by changing of the radius along the scanning path also can be suppressed and don’t confuse the real indications. Results obtained were used for development of inspection technologies applied for gas turbine blade monitoring in different countries (Fig. 7).

Fig. 7. On-site inspection of gas turbine blades with long handle EC probe in Algeria 4.2. Detection of flaws in gas turbine holes Special rotating EC explorer with double differential EC probe based on ELOTEST SR-1 rotor was developed for detection of flaws on the side wall of gas turbine holes (Fig. 8, left). Developed technique was based on ELOTEST 300 type flaw detector application. For EC flaw detector calibration spatial reference standard with 39 mm hole and 4 artificial 0.2; 0.3; 0.5 and 1.0 mm depth like crack flaws situated on hole sidewall was developed and produced. c