Vibration Based Structural Health Monitoring using Time Reversal Acoustics

Vibration based structural health monitoring using Time Reversal Acoustics (TRA)represents a new approach to in-situ nondestructive evaluation of airspace structures. The proposed noncontact technique is based on TRA focusing of high frequency vibrations in tested structures produced by single or several external sources and surface vibration measurements by a scanning laser vibrometer. The application of TRA principles will significantly improve the vibration based NDE system's ability to detect the presence of structural faults and localize damage due to targeted focusing of the acousto-elastic waves. In contrast to conventional acoustic methods of NDE where the dispersion of elastic waves is viewed as an unfavorable phenomena, the TRA methodology takes advantage of this previously undesirable process. Scanning of the TRA focused signal over examined surface provides information necessary for tomographic mapping of damage and degradation. During Phase I, the principles of the TRA system with external sources and a laser vibrometer for damage detection will be developed and feasibility tests will be conducted on composite and metal parts with increasing level of damage including cracks, delamination, fiber breakage, corrosion, and battle damage. The developed TRA software and hardware will form a basis for the prototype that will be built in Phase II.