Residual strain sensor using Al-packaged optical fiber and Brillouin optical correlation domain analysis

Area of Science:

• Materials Science
• Optical Engineering
• Structural Health Monitoring

Background:

• Residual strain in materials can impact structural integrity.
• Optical fiber sensors offer distributed sensing capabilities.
• Packaging influences optical fiber sensor performance.

Purpose of the Study:

• To propose and evaluate an Al-packaged optical fiber as a distributed residual strain sensor.
• To investigate the sensor's performance under tensile stress and impact.
• To assess the long-term reliability of the proposed sensor.

Main Methods:

• Utilized Brillouin optical correlation domain analysis (BOCDA) for strain measurement.
• Employed an Al-packaged optical fiber with varying numbers of Al layers.
• Conducted tensile stress tests, impact experiments, and long-term reliability testing over nine months.

Main Results:

• Quantified Brillouin frequency shifts in response to tensile stress.
• Achieved 87% residual strain detection after stress removal.
• Demonstrated successful detection of residual strain in a composite plate after impact.
• Observed minimal change (4% reduction) in residual strain over nine months, indicating high reliability.

Conclusions:

• The Al-packaged optical fiber functions effectively as a distributed residual strain sensor.
• The sensor exhibits robust performance and reliability for monitoring smart structures.
• This technology holds promise for applications in aerospace and other critical infrastructure.