Nondestructive Evaluation (NDE) Technology Initiative Program (NTIP). Delivery Order 0038: NDE Sensory Monitoring System for Aircraft Structure
Abstract
The concept of a biomimetic sensor system design that can be embedded in aircraft structure is explored in this project. Signal processing techniques for quantifying the sensor responses are studied. In particular, wavelet analysis is used to extract the time frequency information about the acoustic emission (AE) signals and to separate the Lamb wave modes. The continuous sensor used in this biomimetic sensor system was used to monitor fatigue crack extensions in an aluminum plate and in a glass epoxy composite panel. The sensor was found to be sufficiently sensitive to detect fatigue crack growth rates on the order of 4 x 10(exp -6) inch/cycle. The waveforms from the mode I type crack growth showed some differences. Based on these differences, nine different AE signal types were identified and their relative frequency components were examined. Further, continuous sensor with its distributed sensing nodes was shown to be superior to traditional single node AE sensors, particularly for monitoring highly attenuated structures such as composite panels and large regions. In addition, an algorithm for locating the source of acoustic emission signals in a two-dimensional plane from the signal from a single channel continuous sensor was developed and verified through numerical simulations. As a final part of this effort, an emulator of the embedded local processor chip that is a key element in the biomimetic sensor system was developed. (22 figures, 3 refs.)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2003
- Accession Number
- ADA428848
Entities
People
- G. Grandhi
- J. Kermerling
- M. Sundaresan
- S. Uppaluri
Organizations
- North Carolina Agricultural and Technical State University