Quantitative flaw reconstruction from ultrasonic surface wavefields measured by electronic speckle pattern...

Area of Science:

• Non-destructive testing
• Materials science
• Wave mechanics

Background:

• Plate and shell structures are critical in various engineering applications.
• Detecting internal flaws is essential for structural integrity and safety.
• Existing ultrasonic imaging methods have limitations in resolution and applicability to complex geometries.

Purpose of the Study:

• To present a new two-dimensional ultrasonic imaging method for flaws in plate and shell structures.
• To demonstrate the capability of the method to image small defects and complex structures.
• To provide quantitative images of internal inhomogeneities based on material property variations.

Main Methods:

• Utilizing two-dimensional ultrasonic surface wave data acquired via electronic speckle pattern interferometry (ESPI).
• Processing the out-of-plane displacement field of externally excited ultrasonic Lamb waves.
• Deconvolving a free space Green's function from the wavefield to obtain effective scattering source images.

Main Results:

• Simulations confirmed accurate imaging of flaws across various sizes and material contrasts.
• The method successfully imaged flaw features smaller than the acoustic wavelength by utilizing scattered evanescent waves.
• Experimental reconstructions from a flawed aluminum plate demonstrated potential for complex structures.

Conclusions:

• The developed ultrasonic imaging method provides a direct map of internal inhomogeneities.
• The technique shows promise for non-destructive evaluation of complex structures where traditional ESPI interpretation is challenging.
• This advancement offers enhanced capability for detecting subtle flaws in critical engineering components.