Phononic Crystal Waveguides for Structural Health Monitoring Applications

Abstract

This paper reported applications of 3D printed acrylic phononic crystal (PC) waveguide transducers for application within NEWS methods. Experimental evidence has shown to support the mathematical formulation of the imaginary component of the complex wavenumber shift used in the design of circular PCs with sinusoidally corrugated profiles. Experimental evidence has also supported the existence of band gaps resultant from the destructive interference of both incident and reflected fundamental Lamb waves at specific frequency band gaps. These stop bands allow PC transducers to possess their unique feature of natural filters undesired frequencies, for example those originated from the ultrasonic equipment. NEWS tests have finally shown that second harmonic waves generated from the contact surfaces of micro-cracks could be accurately detected with PC waveguide transducers used during ultrasonic transmission. This technology can be applied, in future, for more accurate, automatable, and simpler microcrack detection.