Accession Number:

ADA461299

Title:

Disbond Thickness Evaluation Employing Multiple-Frequency Near-Field Microwave Measurements

Descriptive Note:

Journal article (preprint)

Corporate Author:

MISSOURI UNIV-ROLLA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING

Personal Author(s):

Report Date:

2006-05-01

Pagination or Media Count:

19.0

Abstract:

Near-field microwave nondestructive evaluation NDE techniques have shown great potential for disbond detection in multi-layer dielectric composite structures. The high detection capability associated with these techniques stems from the fact that near-field microwave signals are sensitive to minute variations in the dielectric properties and geometry of the medium in which they propagate. In the past, the sensitivity of the near-field microwave NDE techniques to the presence and properties of disbonds in multi-layer dielectric composites has been investigated extensively. However, a quantitative disbond thickness estimation method has yet to be introduced. In this paper, we propose a maximum-likelihood ML disbond thickness evaluation method utilizing multiple independent measurements obtained at different frequencies. We also introduce a statistical lower limit on the thickness resolution based on the mean squared error MSE in thickness estimation and a given confidence interval. The effectiveness of the proposed ML method is also verified by comparing simulation results with actual measurements.

Subject Categories:

  • Couplers, Fasteners and Joints
  • Test Facilities, Equipment and Methods

Distribution Statement:

APPROVED FOR PUBLIC RELEASE