Local Near Tip Asymptotic Fields and Toughening Mechanisms

Abstract

We have examined the local near tip asymptotic fields and toughening mechanisms for 3 classes of flawed ceramics, i) nominally pure alumina as a function of grain size form 20-150 microns (Al2O3), Partially Stabilized Zirconia (Mg-ZrO2) and hot pressed SHS Titanium Diboride (TiB2). Class (i), in joint cooperation with General Electric Co. investigates the nature and existence of microcracking as a mechanism to toughen ceramics. Using more interferometry we have identified that microcracking exists below grain sizes on the order of 70 microns. Above 70 microns we have identified that crack deflection occurs along the grain boundaries and acts as the principal toughening agent. For class ii), in joint cooperation with Oak Ridge National Laboratory, we have produced for the first time, local in plane asymptotic fields, as well as wake zones for the tetragonal to monoclinic phase transformation surrounding a propagating crack.

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Document Details

Document Type
Technical Report
Publication Date
Apr 23, 1990
Accession Number
ADA221301

Entities

People

  • Jonathan S. Epstein

Organizations

  • Georgia Tech

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Acoustic Emissions
  • Civil Engineering
  • Computational Mechanics
  • Cooperation
  • Crack Tips
  • Cracks
  • Deflection
  • Engineering
  • Grain Boundaries
  • Grain Size
  • Materials
  • Microcracking
  • Military Research
  • Phase Transformations
  • White Light

Readers

  • Materials Science (Mechanical Engineering).
  • Surface Engineering/Surface Coating Technology.