386
K. Bo et al.
Table 33.1 Details of cycle test
Testing medium
Lower pressure
(MPa)
Lower pressure
holding time (s)
Upper pressure
(MPa)
Upper pressure
holding time (s)
46# hydraulic oil 0.2
2.5
2.1
2.5
Table 33.2 Project of cycle and AE testing
Order for collecting AE signal
Cycle times 1
Order for collecting
AE signal
Cycle times
1
500
11
17,000
2
1500
12
19,000
3
2500
13
21,000
4
3500
14
23,000
5
5000
15
25,000
6
7000
16
27,000
7
9000
17
29,000
8
11,000
18
31,500
9
13,000
19
34,000
10
15,000
Note 1: After certain number of cycle times given in this column, cycle testing was suspended and
detected cylinder by AE testing
Fig. 33.3 The graph of cycle and AE testing project
Thresholds were settled at 40 dB. Eight sensors with 150 kHz frequency were
used. Each sensor was connected with a 40 dB pre-amplifier, as shown in Fig. 33.4a.
The coupling agent was vacuum grease. From Fig. 33.4b, sensors were fastened
firmly with scotch tape and fixed with elastic rubber belt. The maximum distance
between two sensors was 303 mm.
In the process of cycling and AE testing, cylinder appearance was monitored and
the AE data was recorded by AE system.