Environmental Engineering Reference
In-Depth Information
Fig. 9.29 The logarithm of the curve length log(L(k)) versus log(k)
We define FD-based damage acuteness index as follows:
J
¼ð
b
max
;
k
=
bx
min
;
k
Þ
FD
max
1
ð
9
:
18
Þ
where b
max,k
is the largest length of the signal curve of every time series as the
interval time is k; b
min,k
is the length of the signal curve which passes through no
damaged region as the interval time is k; FD
max
is the largest value of estimated
FD of the curve of each time series.
Finally, the proposed damage acuteness index was applied to the data from the
PZT sensors 5 and 6 during the second part of the testing procedure. The results
are shown in Fig.
9.30
, where the x and y axis represent respectively the time and
the damage index. These two figures show that the damage index increases greatly
(a)
(b)
20
12
16
10
12
8
8
6
4
4
0
0
100
200
300
400
500
600
0
100
200
300
400
500
600
Time (s)
Time (s)
Fig. 9.30 The damage acuteness index J along the loading time: a the damage index calculated
from PZT sensor 5, b the damage index calculated from PZT sensor 6
