Flat-cladding fiber Bragg grating sensors for large strain amplitude fatigue tests

Area of Science:

• Materials Science
• Mechanical Engineering
• Optical Engineering

Background:

• Accurate measurement of large cyclic strain amplitudes is crucial for material fatigue analysis.
• Traditional strain measurement methods face limitations in extreme strain conditions.

Purpose of the Study:

• To develop and validate a novel flat-cladding fiber Bragg grating sensor for high cyclic strain amplitude testing.
• To assess the sensor's performance and reliability in characterizing material fatigue behavior.

Main Methods:

• Development of a flat-cladding fiber Bragg grating sensor with enhanced bonding strength.
• Implementation of a new bonding process to increase interfacial contact area.
• Conducting push-pull fatigue tests on aluminum and magnesium alloys up to ± 8,000 με.

Main Results:

• The developed sensor successfully performed cyclic strain amplitude tests up to ± 8,000 με.
• High measurement accuracy was demonstrated, with minimal differences in plastic strain amplitude measurements (0.43% to 1.9%).
• The sensor effectively captured asymmetric hysteresis loops in magnesium alloys, correlating well with extensometer data.

Conclusions:

• The flat-cladding fiber Bragg grating sensor is a reliable tool for large cyclic strain amplitude measurements.
• The enhanced bonding and sensor design ensure robust performance in demanding fatigue testing applications.
• This technology offers a validated alternative for precise material fatigue characterization.