Stress non-uniformity in a hollow cylinder torsional sand specimen

Patrick J. Naughton, Brendan C. O'Kelly

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

The hollow cylinder torsional apparatus (HCTA) facilitates more generalized stress path testing although it has been criticized on account of the level of stress non-uniformity that may develop because of the curvature of the test specimen wall. The stress non-uniformity which may develop in dense sand specimens (inner radius, 35.5 mm; outer radius, 50.0 mm; height, 200 mm) over small to medium strain levels in the HCTA was studied using an isotropic linear elastic stress analysis. The stress non-uniformity, quantified in terms of the stress non-uniformity coefficient βR, increased in proportion to the stress ratio R, and was generally acceptable throughout the stress space for R < 1.5. Regions where unacceptable stress non-uniformity may develop were identified in the vicinity of (b,ασ), equal to (1,0°) and (0,90°) and for all values of the parameter b in the vicinity of ασ = 45°. It was found that placing restrictions on the difference in the confining pressures which may be applied across the specimen wall thickness reduced the stress non-uniformity but also limited the regions in stress space that could be probed.

Original languageEnglish
Pages (from-to)117-122
Number of pages6
JournalGeomechanics and Geoengineering
Volume2
Issue number2
DOIs
Publication statusPublished - Jun 2007

Keywords

  • Hollow cylinder torsional apparatus
  • Sand
  • Stress non-uniformity
  • Stress path

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