Force-Displacement Analysis in Diaphragm-Embedded Fiber Bragg Grating Sensors

Area of Science:

• Optical Engineering
• Materials Science
• Sensor Technology

Background:

• Fiber Bragg Grating (FBG) sensors offer precise strain measurement capabilities.
• Diaphragm-embedded FBG sensors are explored for simultaneous force and displacement sensing.
• Understanding strain transmission in FBG sensors under mechanical load is crucial.

Purpose of the Study:

• To analyze the force and displacement characteristics of a diaphragm-embedded FBG sensor.
• To investigate the correlation between FBG wavelength shift, optical power, and applied force/displacement.
• To evaluate the potential for simultaneous force and displacement estimation and material characterization.

Main Methods:

• Numerical analysis using the finite element method (FEM) for linear elastic materials.
• Experimental analysis with controlled displacement and force application on the FBG sensor.
• Analysis of reflected optical power variations and wavelength shift responses.

Main Results:

• A high correlation (R²=0.998) was found between wavelength shift and displacement, indicating direct strain transmission.
• Force showed an indirect relation to strain, dependent on material properties.
• Simultaneous force and displacement estimation achieved RMSE of 0.37 N and 0.05 mm within a limited range.
• FBG sensor demonstrated potential for in situ characterization of viscoelastic material properties.

Conclusions:

• Diaphragm-embedded FBG sensors can accurately measure displacement and, indirectly, force.
• The sensor enables simultaneous estimation of force and displacement with high precision.
• The FBG sensor is suitable for in situ characterization of viscoelastic materials.