Hot-Spot Damage Monitoring in Aerospace Composites Using Acoustic Bandgap (ABG) Sensors

Acoustic bandgap (ABG) sensors are made of a periodic array of inclusions/scatterers embedded in a homogenous elastic matrix. ABG sensors can be thought of as the mechanical analogues of semiconductors. In a semiconductor the electronic bandgap arises as the result of a periodic array in electronic potentials. In an ABG sensor an acoustic bandgap arises as the result of a periodic array of differing acoustic impedances. We suggest that acoustic bandgap sensors can be used to detect and quantify submicron damage in composite laminates. Monitoring changes in the acoustic response of ABG sensors, will allow us to detect submicron damage in the substrate to which the ABG sensors are adhered. We present the results of our recent simulations demonstrating the ability of an ABG sensor made of epoxy matrix with Tungsten inclusions to detect submicron damage in a composite laminate adhered to the ABG sensor. A finite element simulation coupled with acoustic wave analysis using finite difference in time domain (FDTD) method is used to present the ability of ABG crystals to be employed as sensors for submicron damage detection.