A refined Lamb wave reciprocity-based method with enhanced sensitivity for damage detection in composite laminates.

Area of Science:

• Structural Health Monitoring
• Non-Destructive Testing
• Composite Materials

Background:

• Lamb wave reciprocity-based methods are used for composite plate health monitoring.
• Symmetric damage between transmitter-receiver pairs can lead to misjudgment by traditional reciprocity methods.
• Existing methods struggle to detect damage in symmetric locations, compromising structural integrity assessment.

Purpose of the Study:

• To develop a novel method for computing the reciprocity index (RI) using extended Lamb wave signal data.
• To improve the detection of symmetrically located damage in composite plates.
• To enhance the reliability of Lamb wave-based structural health monitoring.

Main Methods:

• Proposed a new method for calculating the reciprocity index (RI) by extending the data length of Lamb wave signals.
• Exploited indirect Lamb waves that interact with damage and other reflectors via multiple paths.
• Defined and validated two modified RIs using experimental data from two case studies.

Main Results:

• The modified RIs demonstrated high sensitivity to damage, including cases located symmetrically between transmitter-receiver pairs.
• The new indices effectively distinguished between healthy and damaged states, showing a low threshold for pristine conditions.
• Indirect waves provided crucial information, revealing damage missed by direct wave analysis.

Conclusions:

• The proposed method using indirect Lamb waves significantly enhances the detection capabilities for symmetrically located damage.
• Modified reciprocity indices offer a more robust and reliable approach to structural health monitoring of composite plates.
• This advancement improves the accuracy and effectiveness of non-destructive testing for composite structures.