Dynamic tensile‐failure‐induced velocity deficits in rock

Allan M. Rubin, Thomas J. Ahrens

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Planar impact experiments were employed to induce dynamic tensile failure in Bedford limestone. Rock discs were impacted with aluminum and polymethyl methacralate (PMMA) flyer plates at velocities of 10 to 25 m/s. Tensile stress magnitudes and duration were chosen so as to induce a range of microcrack growth insufficient to cause complete spalling of the samples. Ultrasonic P‐ and S‐wave velocities of recovered targets were compared to the velocities prior to impact. Velocity reduction, and by inference microcrack production, occurred in samples subjected to stresses above 35 MPa in the 1.3 μs PMMA experiments and 60 MPa in the 0.5 μs aluminum experiments. Using a simple model for the time‐dependent stress‐intensity factor at the tips of existing flaws, apparent fracture toughnesses of 2.4 and 2.5 MPa m½ are computed for the 1.3 and 0.5 μs experiments. These are a factor of ∼ 2 to 3 greater than quasi‐static values. The greater dynamic fracture toughness observed may result from microcrack interaction during tensile failure. Data for water‐saturated and dry targets are indistinguishable.

Original languageEnglish (US)
Pages (from-to)219-222
Number of pages4
JournalGeophysical Research Letters
Volume18
Issue number2
DOIs
StatePublished - Feb 1991
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

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