Exploring the Acoustic Nonlinearity for Monitoring Complex Aerospace Structures
Abstract
The project explores the acoustic nonlinearity for monitoring complex aerospace structures. A particular attention is given to structural connectors and joints. For these structural elements, am embedded nonlinear ultrasonic (ENU) approach is developed that utilizes unobtrusive piezoelectric wafer active sensors bonded to or embedded into structural elements. The nonlinear manifestation of structural damage is studied and various damage identification methodologies are suggested. Experimental results show feasibility of ENU monitoring of bolted joints in thin-walled aeronautical structures and complex space structures with iso-grinds. The proposed acousto-elastic method has shown potential in quantifying the torque level on a bolt and locating loosened bolts. Promising results were obtained for ENU monitoring of epoxy bonds. Classical and new nonlinear acoustic methods were found to be effective in detecting relatively large damage, but showed misinterpretation errors for specimens with damage of smaller size. A new nonlinear acoustic technique was suggested for short pulse measurements in aerospace structures. Correlation of experimental results obtained with a classical nonlinear acoustic approach and a new technique was established. It is suggested that ENU may be used either as a stand-alone SHM technique or as a complement to existing embedded ultrasonic methods.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 27, 2008
- Accession Number
- ADA479504
Entities
People
- Andrei N. Zagrai
- Derek T. Doyle
Organizations
- New Mexico Institute of Mining and Technology