Photoelastic Studies of Crack Propagation and Arrest in Polymers and 4340 Steel.

Abstract

This report describes the progress made during the fourth year on a research program dealing with the dynamic characterization of fracture. The significant findings during the past year include: (1) An evaluation of the BCL procedure for determining K sub IDm' indicated that BCL reference curves predict velocities that are too high and predict values of the stress intensity factor which are too low. (2) An evaluation of the MRL procedure for determining K sub Ia showed that K sub Ia was within 4.5 per cent of the photoelastically determined value of K sub Im. (3) A new ultra high speed recording system was developed for recording dynamic fringe patterns in birefringent coatings. (4) Studies of the stress intensity factor associated with propagating cracks in 4340 steel gave a a vs K relation which compared favorably with results previously published by BCL. (5) Comparisons of crack behavior in duplex specimens fabricated from plastic/plastic and steel/steel indicate that the processes of crack propagation, crack arrest and crack re-initiation are similar in both types of specimens. (6) The investigation of crack propagation in ring specimens with mechanically simulated thermal stresses showed significant differences in the stress intensity factor associated with static crack extension and dynamic crack propagation. Dynamic propagation occurs at much lower values of K than static crack extension. (7) Studies of dynamic crack propagation in CT specimens (Homalite 100) fabricated with and without face grooves indicated that the effect of the face grooves is not significant on crack behavior. (8) The physical and mechanical properties of Araldite B were determined and found to be in close agreement with results published previously.

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Document Details

Document Type
Technical Report
Publication Date
Dec 01, 1978
Accession Number
ADA304451

Entities

People

  • G. R. Irwin
  • J. T. Metcalf
  • J. W. Dally
  • T. Kobayashi
  • W. L. Fourney

Organizations

  • University of Maryland

Tags

Communities of Interest

  • Energy and Power Technologies
  • Weapons Technologies

DTIC Thesaurus Topics

  • Computer Programming
  • Computer Programs
  • Computers
  • Creep
  • Data Analysis
  • Elastic Properties
  • Flash Lamps
  • Fracture (Mechanics)
  • Measurement
  • Mechanical Properties
  • Mechanics
  • Modulus Of Elasticity
  • Recording Systems
  • Stress Waves
  • Test And Evaluation
  • Test Methods
  • Welded Joints

Readers

  • Materials Science (Mechanical Engineering).
  • Mechanical Engineering/Mechanics of Materials.