Depth-Dependent Characterization of Vertical Cracks in Concrete Using Lamb Wave Active Sensing

Area of Science:

• Materials Science
• Civil Engineering
• Nondestructive Testing

Background:

• Vertical cracks in concrete pose challenges for conventional nondestructive testing (NDT) and structural health monitoring (SHM).
• Elastic wave-based methods show promise but require repeatable and tunable excitation sources for effective crack characterization.

Purpose of the Study:

• To develop and apply an active sensing system with a linear impact actuator for elastic-wave-based NDT of vertical concrete cracks.
• To investigate the influence of crack depth and propagation direction on elastic wave behavior.

Main Methods:

• Utilized a linear impact actuator as a tunable source for elastic-based NDT on a concrete slab with controlled vertical cracks.
• Employed A0 Lamb wave responses and quantified phase-velocity anisotropy and effective quality factor using crack-parallel and crack-perpendicular sensor arrays.

Main Results:

• Phase velocities were higher for crack-parallel wave propagation than crack-perpendicular, with anisotropy increasing with crack depth.
• Effective quality factor decreased with crack depth and showed anisotropic behavior, being lower for crack-perpendicular measurements.

Conclusions:

• Controllable and repeatable impact excitation provides a reliable framework for characterizing vertical concrete cracks using elastic waves.
• The developed system demonstrates potential for enhanced structural health monitoring of concrete structures.