33 Experiment Research on Acoustic Emission of Impact-Damaged …
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Fig. 33.1 Drop test and punch designed for this work
Fig. 33.2 a Actual drop test, b impact damage in surface of cylinder
33.2.2 Cycling Test and AE Testing Procedure
To replicate the in-service condition of repeated depressurization-pressurisation,
cylinder with artificial impact damage was subjected to pressure cycles ranging from
a lower pressure of 0.2 MPa to a upper pressure of 2.1 MPa at a constant frequency
of 7.5 cycles per minute by a 10 MPa fatigue testing machine. The upper pressure
was the same as working pressure of the cylinder. More information of cycle test
was shown in Table 33.1.
Cycle testing was suspended after a certain number of cycles and detected the
cylinder by AE testing. In AE testing, pressurization was from 0.2 to 2.4 MPa by a
manual pump, then decompressed the cylinder after holding for 10 min in the pressure
of 2.4 MPa. AE signals were collected during this overall process. The project of
cycle and AE testing was shown in Table 33.2 and Fig. 33.3.