The condition of bolted connections significantly affects the structural safety. However, conventional bolt tension sensors fail to provide precise measurements due to their bulky size or inadequate stability. This study employs the piezoresistive effect of crystalline silicon material to fabricate an ultrathin sensor. The sensor exhibits a linear relationship between pressure and voltage, an exceptional stability under varying temperatures, and a superior resistance to corrosion, making it adaptable and user-friendly for applications of high-strength bolt tension monitoring. A monitoring system, incorporating the proposed sensor, has also been developed. This system provides real-time display of bolt tension and enables the assessment of sensor and structural conditions, including bolt loosening or component failure. The efficacy of the proposed sensor and monitoring system was validated through a project carried out at the Xiluodu Hydropower Plant. According to the results, the sensor and online monitoring system effectively gauged and proficiently conveyed and stored bolt tension data. In addition, correlations were created between bolt tensions and essential unit parameters, such as water head, active power, and pressures at vital points, facilitating anomaly detection and early warning.
create, delete, and name projects; enter and modify project full-cycle information
user rights setting
create and delete user accounts; initialize passwords; assign permissions of using software, project information, and historical data
Acquisition management
acquisition instrument management
create, delete, name, and number acquisition instruments; set measuring parameters (sampling frequency, sensitivity, compensation value, etc.)
sensor management
create, delete, name, and number sensors; set sensor types and parameters; edit sensor calculation formulas; set sensor connection diagram
measuring point management
create, delete, name, number, and locate measuring points; associate measuring points with sensors
acquisition controlling
establish communication to acquisition instrument; start and stop acquisition remotely; set data transmission method and storage location
Data processing management
data writing
store measured data automatically; enter user-defined data manually; combine data from different sources
statistical analysis
summarize database according to time (weekly, monthly, or yearly) and location; calculate statistical parameters for variables (means, variances, covariances, and correlation coefficients)
time-frequency domain analysis
conduct time series analysis in time or frequency domains; identify structural parameters and modes
Display management
measuring data real-time display
real-time display of tension changes at each measuring point based on latitude and longitude coordinates
diversified display of analyzed data
diversified display for current and historical signals with the corresponding calculated parameters; modify image and table parameters (appearance style, axis, title, etc.)
Risk warning management
warning rule setting
enter warning rules based on related standards or previous researches; set warning ranges, thresholds, levels, and displaying methods
warning log recording
automatically generate, store, and sort warning logs; record abnormal data and measures taken during the whole warning process
Tab.1
Fig.7
Fig.8
Fig.9
Torque (kN·m)
First trial
Second trial
Third trial
Voltage (mV)
Tension (kN)
Voltage (mV)
Tension (kN)
Voltage (mV)
Tension (kN)
0
34
0
34
0
35
?0.5
440
?56
45
?137
85.5
?163
98.5
700
?177
105.5
?232
133
?230
132
1000
?297
165.5
?361
187.5
?314
174
Tab.2
Torque (kN·m)
First trial
Second trial
Third trial
Voltage (mV)
Tension (kN)
Voltage (mV)
Tension (kN)
Voltage (mV)
Tension (kN)
0
38
0
38
0
37
0.5
440
?168
103
?186
112
?206
122
600
?256
147
?268
153
?264
151
1050
?369
203.5
?382
210
?374
206
Tab.3
Fig.10
Fig.11
Fig.12
Fig.13
Fig.14
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