Eddy Current for Detecting Second Layer Cracks Under Installed Fasteners

Abstract

The detection of second layer Cracks Under Fasteners (CUF) persists as an Air Force Logistics need. This work seeks to extend technology developed for detecting cracks in aluminum alloy substructure below graphite-epoxy skins, to structures with an aluminum first layer. Improvements to the design of the Northrop Low Frequency Eddy Current Array (LFECA) system are identified to improve sensitivity to CUFs in aluminum-over-aluminum structures. The probe core shape, dimensions, and coil configurations were optimized for detection with installed fasteners and metallic skin. A multiparameter analysis algorithm is applied to enable flaw discrimination from centering variations, edge responses and other sources of noise. The study also quantifies the capabilities and limitations of the LFECA system. Eddy current, Low frequency eddy current, Cracks, CUFs, Nondestructive Evaluation (NDE).

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Document Details

Document Type
Technical Report
Publication Date
Apr 01, 1994
Accession Number
ADA282412

Entities

People

  • William R. Sheppard

Tags

Communities of Interest

  • Advanced Electronics
  • Sensors

DTIC Thesaurus Topics

  • Air Force
  • Aircrafts
  • Contracts
  • Corporations
  • Detection
  • Detectors
  • Eddy Currents
  • Ferrites
  • Frequency
  • Frequency Response
  • Geometry
  • Magnetic Fields
  • Materials
  • Measurement
  • Military Aircraft
  • Two Dimensional
  • United States

Fields of Study

  • Physics

Readers

  • Aerospace Engineering
  • Medical Imaging.
  • Structural Health Monitoring of Composite Structures.