33 Experiment Research on Acoustic Emission of Impact-Damaged …
389
Fig. 33.7 AE energy VS time of pressurization after a 1500 cycle times, b 7000 cycle times,
c 19,000 cycle times, d 23,000 cycle times, e 31,500 cycle times, f 34,000 cycle times
33.3.4 Comparisons and Analysis
According to the results above listed, characteristics of AE cumulative hit number
were closely in accordance with characteristics of AE energy.
Combining with results of cumulative hit number and AE energy, more information can be acquired. Overall process could be divided in four phases according
to the diagram of Fig. 33.6. At initial phase(i.e. 0–1500 cycles), because of impact
damage in cylinder, stress distribution was uneven and cylinder composite had stress
concentration in site of impact damage, fiber bearing high stress in the location of
stress concentration may fracture when pressured, accounting for the relatively high
AE cumulative hit number and energy of signals.
In the second phase (1500–15,000 cycles), localized high stress released in
previous phase and new damage had not initiated or propagated to a certain degree, so
cylinder was in a stable state with less and less AE hit number and few signals with
high energy. In the third phase (17,000–25,000 cycles), AE hit number increased
and signals with high energy were captured again. It was a gradual process of
accumulation of damage.
Through the diagram in Fig. 33.6, cumulative hit number which reflected AE
activity after 1500 cycle times was nearly the same as the number after 23,000
cycle times. There were AE signals with high energy in AE testing. AE testing
results showed certain damage in cylinder composite in two cases. One case was that
impacted damage and other case was that damage accumulated with cycle testing.
Therefore, AE testing is an effect method to detect potential impact damage in fullwrapped composite cylinder with non-metallic liner.
In the four phase (26,000–31,500 cycles), slope of the curve, which represents
growth rate of AE cumulative hit number was more steep. More signals with high
energy were collected. Damage was propagating severely and cylinder was very
389
Fig. 33.7 AE energy VS time of pressurization after a 1500 cycle times, b 7000 cycle times,
c 19,000 cycle times, d 23,000 cycle times, e 31,500 cycle times, f 34,000 cycle times
33.3.4 Comparisons and Analysis
According to the results above listed, characteristics of AE cumulative hit number
were closely in accordance with characteristics of AE energy.
Combining with results of cumulative hit number and AE energy, more information can be acquired. Overall process could be divided in four phases according
to the diagram of Fig. 33.6. At initial phase(i.e. 0–1500 cycles), because of impact
damage in cylinder, stress distribution was uneven and cylinder composite had stress
concentration in site of impact damage, fiber bearing high stress in the location of
stress concentration may fracture when pressured, accounting for the relatively high
AE cumulative hit number and energy of signals.
In the second phase (1500–15,000 cycles), localized high stress released in
previous phase and new damage had not initiated or propagated to a certain degree, so
cylinder was in a stable state with less and less AE hit number and few signals with
high energy. In the third phase (17,000–25,000 cycles), AE hit number increased
and signals with high energy were captured again. It was a gradual process of
accumulation of damage.
Through the diagram in Fig. 33.6, cumulative hit number which reflected AE
activity after 1500 cycle times was nearly the same as the number after 23,000
cycle times. There were AE signals with high energy in AE testing. AE testing
results showed certain damage in cylinder composite in two cases. One case was that
impacted damage and other case was that damage accumulated with cycle testing.
Therefore, AE testing is an effect method to detect potential impact damage in fullwrapped composite cylinder with non-metallic liner.
In the four phase (26,000–31,500 cycles), slope of the curve, which represents
growth rate of AE cumulative hit number was more steep. More signals with high
energy were collected. Damage was propagating severely and cylinder was very