Measurement of Strain Induced by Impact with Fiber Bragg Grating

2008 ◽  
Vol 381-382 ◽  
pp. 435-438
Author(s):  
Ping Yu Zhu ◽  
D. Liu ◽  
Y. Lin
Keyword(s):  
Composite Material ◽  
Fiber Bragg Grating ◽  
Time Domain ◽  
High Frequency ◽  
Impact Test ◽  
Bragg Grating ◽  
Experiment Data ◽  
Frequency Limit ◽  
Fiber Bragg Grating Sensors ◽  
Frequency Components

After deriving the propagation formula of stress wave through incident bar, the measured signals both in horizontal impact test and drop impact tests are investigated with novel fiber Bragg grating sensors(FBGs). Especially those strain signals from FBGs which mounted on the surface of an incident bar are studied. The signals in impactor and the FBGs embedded in the composite material under similar test condition are compared. The dropping and impacting models have been setup. The experiment data measured in a lab are analyzed both in time-domain and in frequency domain. Those ultra-high frequency components in the above strain signals can not be obtained by current FBG measurement system due to frequency limit of the demodulation system. Further study to improve the frequency of demodulation system will be done in next step.

scholarly journals Fiber Bragg Grating Sensors for Underwater Vibration Measurement: Potential Hydropower Applications

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4272
Author(s):  
Oscar de la Torre ◽  
Ignazio Floris ◽  
Salvador Sales ◽  
Xavier Escaler
Keyword(s):  
Fiber Bragg Grating ◽  
Numerical Models ◽  
Vibration Measurement ◽  
Quality Data ◽  
Bragg Grating ◽  
Laser Vibrometer ◽  
Main Concern ◽  
High Expectations ◽  
Fiber Bragg Grating Sensors ◽  
Hydraulic Machinery

The present paper assesses the performance and characteristics of fiber Bragg grating sensors, with a special interest in their applications in hydraulic machinery and systems. The hydropower industry is turning to this technology with high expectations of obtaining high quality data to validate and calibrate numerical models that could be used as digital twins of key assets, further strengthening the sector’s relevant position within industry 4.0. Prior to any validation, fiber Bragg grating sensors’ ability to perform well underwater for long periods of time with minimal degradation, and their ease of scalability, drew the authors´ attention. A simplified modal analysis of a partially submerged beam is proposed here as a first step to validate the potential of this type of technology for hydropower applications. Fiber Bragg grating sensors are used to obtain the beam’s natural frequencies and to damp vibrations under different conditions. The results are compared with more established waterproof electric strain gauges and a laser vibrometer with good agreement. The presence of several sensors in a single fiber ensures high spatial resolution, fundamental to precisely determine vibration patterns, which is a main concern in this industry. In this work, the beam’s vibration patterns have been successfully captured under different excitations and conditions.

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