Rapid Detection of Falsely Marked Bolts and Large Screws

Abstract

Falsely marked steel fasteners are of concern, particularly SAE grade 5.2 threaded fasteners marked as grade 5 and grade 8.2 threaded fasteners marked as grade 8. The object of this research was to determine if an electromagnetic nondestructive test method could be used to detect falsely marked fasteners. The proposed test method consisted of measuring the impedance of a probe at two test frequencies and two magnetic field levels when in close proximity to the fastener head. Test frequencies explored ranged from 1 khz to 2 MHz. Magnetic fields ranged up to 12 kG. The 8-dimension state vector generated by this type of measurement was insufficient to sort fastener grades. The reason for this inability to sort is not because of differences in plating, but is due to the relative insensitivity of the steel electrical conductivity and magnetic permeability to fastener grade.

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 1990
Accession Number
ADA225284

Entities

People

  • Duane P. Johnson

Organizations

  • Exponent

Tags

DTIC Thesaurus Topics

  • Alloys
  • Carbon
  • Chemical Composition
  • Chemistry
  • Conductivity
  • Contracts
  • Detection
  • Eddy Currents
  • Electrical Conductivity
  • Failure Analysis
  • Impedance
  • Impedance Bridges
  • Magnetic Fields
  • Measurement
  • Specifications
  • Steel
  • Test Methods

Readers

  • Electrical Engineering
  • Materials Science and Engineering.
  • Systems Analysis and Design