Acoustic Emission Signal Entropy as a Means to Estimate Loads in Fiber Reinforced Polymer Rods

Area of Science:

• Materials Science
• Civil Engineering
• Structural Health Monitoring

Background:

• Fiber-reinforced polymer (FRP) rods are crucial for corrosion resistance in civil infrastructure.
• Accurately determining loads on in-service FRP structures is a significant challenge.

Purpose of the Study:

• To develop a novel method for estimating applied loads on FRP rods using acoustic emission (AE) entropy.
• To investigate the relationship between AE signal entropy and applied load levels in FRP materials.

Main Methods:

• Utilizing the entropy of acoustic emissions (AE) generated by FRP rods to infer applied loads.
• Defining high-entropy AE hits based on the one-sided Chebyshev's inequality (k=2) using a baseline entropy histogram.
• Analyzing the fraction of high-entropy AE hits in glass FRP and carbon FRP rods under increasing loads.

Main Results:

• A direct correlation was observed between increasing applied loads and a higher fraction of AE hits with elevated entropy.
• In glass FRP rods, a 20% high-entropy AE hit fraction was reached around 40% of ultimate load.
• In carbon FRP rods, this 20% threshold was observed at approximately 50% of ultimate load.

Conclusions:

• Monitoring the fraction of high-entropy AE hits provides a viable approach for estimating the in-service loads on FRP rods.
• This AE-based method offers a promising tool for structural health monitoring and integrity assessment of FRP civil structures.