Lamb wave line sensing for crack detection in a welded stiffener

Area of Science:

• Materials Science
• Mechanical Engineering
• Non-Destructive Testing

Background:

• Lamb wave-based structural health monitoring is crucial for detecting damage in metallic structures.
• Detecting cracks in welded joints presents challenges due to complex wave reflections and stress concentrations.
• Existing methods struggle to differentiate crack signals from structural noise in real-world applications.

Purpose of the Study:

• To propose and validate a novel Lamb wave line sensing technique for accurate crack detection.
• To overcome the challenge of mixed Lamb wave modes and reflections in complex waveguides, particularly in welded joints.
• To enhance crack detectability and minimize false alarms in structural health monitoring systems.

Main Methods:

• Utilizing a frequency-wavenumber domain analysis to extract crack-induced Lamb wave modes.
• Employing a line sensing approach along a single measurement path.
• Experimental and numerical validation on vertically stiffened metallic structures.

Main Results:

• The proposed technique successfully identifies and localizes subsurface cracks in welded stiffeners.
• It effectively distinguishes crack signals from reflections originating from the welded joint and the stiffener.
• The method demonstrates robustness against environmental and operational variations by avoiding baseline data comparison.

Conclusions:

• The novel Lamb wave line sensing technique offers enhanced crack detectability in welded structures.
• This method provides a reliable approach for structural health monitoring, minimizing false alarms.
• The technique is validated for identifying and localizing subsurface cracks in complex metallic structures.