Probability of Detection in SQUID Nondestructive Evaluation
Abstract
Superconducting Quantum Interference Device (SQUID) magnetometers are being used as tools for Nondestructive Evaluation (NDE) to detect and characterize defects in aging aircraft. To evaluate SQUID NDE reliability. a Probability of Detection (POD) analysis has been done. A Boundary Element Method (BEM) measurement model using a Green's function developed specifically for crack problems has been constructed for use in the POD analysis. The model simulates the 2-D images of the magnetic field obtained by scanning a SQUID magnetometer over a plate containing a crack and carrying an injected DC current. POD curves were generated through Monte Carlo simulation using distributions derived from sensitivity analyses and experimental noise measurements. For the conditions simulated, crack lengths of 1.4 mm (DC measurement) and 0.0134 mm (AC measurement) could be found with 90% probability of detection and 95% confidence. These small crack lengths suggest that additional experimental noise factors will have be incorporated into the POD analysis before realistic SQUID NDE capability can be accurately quantified.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 21, 1998
- Accession Number
- ADA342741
Entities
People
- Anthony P. Ewing
- John P. Wikswo, Jr.
Organizations
- Vanderbilt University