Authors

S. Raghavan;P. Imbrie

Comments

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Abbreviated Journal Title

J. Synchrot. Radiat.

Keywords

X-ray diffraction; stress mapping; alumina; STIMULATED LUMINESCENCE SPECTROSCOPY; STRAIN; DEFORMATION; COMPOSITES; CERAMICS; STRENGTH; SAPPHIRE; COATINGS; BEHAVIOR; Instruments & Instrumentation; Optics; Physics, Applied

Abstract

The ability to achieve uniform stress in uniaxial compression tests of polycrystalline alumina is of significance for the calibration of piezospectroscopic coefficients as well as strength studies in ceramics. In this study high-energy X-rays were used to capture powder diffraction profiles over a half-section of a polycrystalline alumina parallelepiped sample under an increasing uniaxial compressive load. The data were converted to strain and results were used for stress mapping of the sample. Stress maps from the study quantify the higher stresses at the sample-platen contact interface and reveal the evolution of the stress distribution in these specimens with load. For the geometry of the samples used, at the center section of the specimen the overall magnitudes of the compressive stresses were found to be 20% higher compared with the average expected theoretical stress based on the applied load and cross-sectional area. The observed compressive stresses at the corners of the parallelepiped specimen were 62% higher and shear stresses were observed at the specimen interface to the load mechanism. The effects, seen at the interface, can lead to premature failure at these locations and can affect the accuracy of calibration of spectral peaks with stress as well as compression strength measurements. The results provide important information that can be used to establish guidelines on material and geometry considerations in developing compression tests on high-strength ceramics.

Journal Title

Journal of Synchrotron Radiation

Volume

18

Publication Date

1-1-2011

Document Type

Article

Language

English

First Page

497

Last Page

505

WOS Identifier

WOS:000291401900023

ISSN

0909-0495

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