Journal of Sensors

Research Article

Comparative Assessment and Experimental Validation of a Prototype Phase-Optical Time-Domain Reflectometer for Distributed Structural Health Monitoring

Table 3

The dominant frequencies revealed by each technology: PO (Phase-OTDR), FBG, GBRI, and LT. Bold values: frequencies common to all the sensors of the same technology; nonbold values: weak frequency signals, present in many but not all sensors of a technology; values in square brackets: correspond to the excitation frequencies and, therefore, are expected; values in parenthesis: frequencies that appear only for certain technologies and are related to the method used.
ExcitationTest #Dominant frequencies revealed [Hz]
1 Hz
No damage		1
LT pos. 1		PO: [1], 72
FBG: [1], 72
GBRI: [1], (9.5, 25, 50), 72, (90.6)
LT: [1]
8
LT pos. 2		PO: [1], 72
FBG: [1], 72
GBRI: [1], (9.5, 50), 72, (90.6)
LT: [1], 51.6
23 Hz3
no damage
LT pos. 1		PO: [23], 46, 66, 69, 72, 89, 92, 112, 115
FBG: [23], 46, 66, 69, 72, 89, 92, 112, 115
GBRI: (9.4), [23], 46, (50), 69, (90.6)
LT: [23], 46, 69
10
no damage
LT pos. 2		PO: 7.7, 15.3, [23], 46, 69, 72, 92, 112, 115
FBG: 7.7, 15.3, [23], 46, 69, 72, 92, 112, 115
GBRI: 7.7, 15.3, [23], 46, (50), 69, (90.6)
LT: 7.7, 15.3, [23], 46, 69
14
no damage
LT pos. 2		PO: 11.5, [23], 34.5, 46, 57.5, 66, 69, 89, 92, 112, 115
FBG: 11.5, [23], 34.5, 46, 57.5, 66, 69, 89, 92, 112, 115
GBRI: 11.5, [23], 34.5, 46, (90.6)
LT: 11.5, [23], 46, 69
18
damage shaker south
LT pos. 2		PO: [23], 46, 66, 69, 72, 89, 92, 112
FBG: 20, [23], 46, 66, 69, 72, 89, 92, 112
GBRI: (9.4), 21.5, [23], 46, 69, (90.6), 92
LT: [23], 46
White noise6
no damage
LT pos. 1		PO: 24, 72
FBG: 23, 24, 72
GBRI: (9.5, 25, 50, 90.6)
LT: 7.6, (9.5), 14.2, 24
13
no damage
LT pos. 2		PO: 7.6, 23, 24, 72
FBG: 7.6, 23, 24, 72
GBRI: 7.6, (9.4), 23, 24, (25, 50, 90.6)
LT: 7.6, 24
15
no damage
LT pos. 2		PO: 20.3, 23, 24, 72
FBG: 7.6, 20.3, 23, 24, 72
GBRI: 7.6, (9.5), 20.3, 23, 24, (25, 50), 81, (90.6)
LT: 7.6, (9.5), 23
7.4 Hz
No damage		2
LT pos. 1		PO: 1.62, [7.4], 72
FBG: [7.4], 22.2, 72
GBRI: [7.4], (9.4), 22.2, (50, 90.6)
LT: [7.4], 22.2
9
LT pos. 2		PO: [7.4], 22.2, 72
FBG: [7.4], 22.2, 72
GBRI: [7.4], (9.4, 50, 90.6)
LT: [7.4], (9.3)
1-10 Hz sweep
No damage		4
LT pos. 1		PO: 7.5, 14.2, 16, 17.5, 20.5, 72
FBG: 7.5, 14.2, 16, 17.5, 20.5, 72
GBRI: 7.5, 17.5, 20.5, (25, 50, 90.6)
LT: 7.5, 16, 17.5
11
LT pos. 2		PO: 7.6, 16, 17.5, 20.5, 72
FBG: 7.6, 16, 17.5, 20.5, 72
GBRI: 7.6, 17.5, 20.5, (25, 50, 90.6)
LT: 7.6, 16, 17
5-50 Hz sweep
No damage		5
LT pos. 1		PO: 7.5, 20.5, 23, 91.2
FBG: 7.5, 20.5, 23, 25, 91.2
GBRI: 7.5, 20.5, 23, 24, (25, 50, 90.6)
LT: 7.5, 16, 20.5, 23
12
LT pos. 2		PO: 20.3, 23
FBG: 20.3, 23
GBRI: 7.5, (9.4), 20.3, 23, (25), 44.7, (50, 90.6)
LT: 7.5, 23
White noise16
damage 1 center north
LT pos. 2		PO: 20.3, 23, 24, 72
FBG: 7.6, 20.3, 23, 24, 72
GBRI: 7.6, (9.5), 23, 24, (25, 50), 81, (90.6)
LT: 7.6, (9.5), 14, 16, 23, 24
17
damage 2 shaker south LT pos. 2		PO: 20.3, 23, 24, 72
FBG: 7.6, 20.3, 23, 24, 72
GBRI: 7.6, (9.5), 23, 24, (25, 50), 81, (90.6)
LT: 7.6, (9.5), 14, 16, 23, 24
Shock
No damage		7
LT pos. 1		PO: 7.6, 72
FBG: 7.6, 72
GBRI: 7.6, (50, 90.6)
LT: 7.6