<title>Fiber Bragg gratings for civil engineering applications</title>

Effectiveness and optimization of fiber Bragg grating sensor as embedded strain sensor

“…The fiber Bragg grating sensors (FBGSs) have attracted more and more attention as embedded sensors to monitor or measure the internal strain of composite structures [1][2][3][4][5][6][7][8][9]. They possess the inherent advantages of optic fiber sensors, such as being light in weight, small in size, flexible, easily embedded into structures and immune to electromagnetic field.…”

“…Then embedded in a host, the FBGS can be used to measure the internal strain of the host. The principle of measurement by an embedded FBGS is based on two assumptions [14]: (1) the optic fiber's axial strain is equal to that of the host in the optic fiber direction; (2) there is no transverse strain from the host to be coupled to the optic fiber. Then the shift of the Bragg wavelength has a linear relation with the strain in the host in the optic fiber direction.…”

“…The second assumption that the optic fiber's axial strain is equal to that of the host in the optic fiber direction implies that the presence of the embedded FBGS has no or little effect on the strain distribution of the host and what the sensor measures should be the strain of the host without the sensor. In real situations, therefore, there are three issues critical to the measurement effectiveness of an embedded FBGS: (1) whether the effect of an embedded optic fiber on the initial host strain field is negligible; (2) whether the optic fiber's axial strain is close enough to that of the host in the optic fiber axial direction and (3) whether EPR υ * can be regarded as a constant during the measurement. If EPR is a constant but not equal to υ, it is necessary to calibrate the sensor in order to determine the value of f after it is embedded into a host.…”

Temperature sensing in microwave heating of concrete using fibre Bragg grating sensors

“…For this reason, an enormous number of fibre optic sensor types have been developed over a very short period of time. Recently, fibre Bragg grating (FBG) optical sensors have attracted a great deal of attention as reliable temperature and strain sensors, which have found widespread applications in civil engineering (Maher et al, 1996;Wang et al, 2001;Lin et al, 2004). These sensors relate the changes in the wavelength of the reflected wave to the desired measurand.…”

Monitoring the Damage State of Fiber Reinforced Composites Using an FBG Network for Failure Prediction

“…There have been several efforts reported in the open literature proposing to utilize FBG sensors to monitor internal strain states of composite structures [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. For example, Takeda et al introduced a new method to predict damage patterns and strains of notched composite laminates with embedded FBG sensors utilizing a layer-wise finite element model [ 24 ].…”