PSI - Issue 13

Hikaru Yamaguchi et al. / Procedia Structural Integrity 13 (2018) 1183–1188 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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From the above experiment, it might be concluded that the CTOA resistance value is different between the DWTT and full-scale pipe burst test. Therefore, a care should be taken when using CTOA resistance value obtained by DWTT for analyzing dynamic crack propagation behavior in pipelines. There might be some reasons for the discrepancy: difference in crack velocity and difference in plastic constraint between the tests. Because the present experiment is limited to only one material, more data must be necessary for establishing factors controlling CTOA resistance value.

(a) Before bust

(b) After burst

Fig.6 Tested pipe before and after burst.

Fig.7 Crack velocity determined from strain changes. 0 100 200 300 400 -1.600-1.200-800 -400 0 400 800 1.2001.600 Crack velocity [m/s] Distance from center [mm] North South

Fig.8 High-speed camera images of burst test, north side.

(a) higher magnification (b) spatial arrangement of camera and crack, schematic Fig.9 Higher magnification near crack-tip and schematic of calculating CTOA.