Automatic Optical Crack Tracking for Double Cantilever Beam Specimens

Abstract

An automatic crack tracking scheme is developed for measuring the tensile opening (mode I) interlaminar fracture toughness (GIc) of continuous glass fiber-reinforced composite materials. The technique is directly compared to ASTM standard D5528, which contains a manual procedure to obtain GIc values from crack length data using a double cantilever beam (DCB) specimen. In this study, a custom computer program with edge detection software rapidly, automatically, and accurately tracks the crack front in translucent DCB specimens by optically monitoring dissimilarities between delaminated and intact portions of the sample. The program combines mechanical testing, image processing, and data collection subroutines into a single interface. The technique is compatible with sample geometries and fabrication processes described in ASTM D5528, and it requires only the addition of a charge-coupled device (CCD) and light source. Compared with the manual techniques outlined in the ASTM standard, the introduced method provides enhanced resolution and reduced workload to determine crack length and resulting GIc of continuous glass fiber-reinforced composite DCB samples.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2015
Accession Number
AD1003364

Entities

People

  • B. Krull
  • J. Patrick
  • K. Hart
  • N. R. Sottos
  • Stephen White

Organizations

  • University of Illinois Urbana–Champaign

Tags

Communities of Interest

  • Air Platforms
  • Energy and Power Technologies
  • Space

DTIC Thesaurus Topics

  • Automatic Tracking
  • Change Detection
  • Charge Coupled Devices
  • Composite Materials
  • Computer Programs
  • Digital Images
  • Fiber Reinforced Composites
  • Fibers
  • Image Processing
  • Materials
  • Materials Laboratories
  • Materials Processing
  • Materials Science
  • Materials Testing
  • Mechanics
  • Military Research
  • Polymer Matrix Composites

Readers

  • Image Processing and Computer Vision.
  • Structural Health Monitoring of Composite Structures.