Slow dynamics in the nonlinear elastic response of Berea sandstone
- Los Alamos National Laboratory, Los Alamos, New Mexico (United States)
A typical resonance curve{emdash}measured acceleration versus drive frequency{emdash}made on a thin bar of rock shows peak bending with a softening (nonlinear) modulus as drive levels are increased. The shapes of these nonlinear resonance curves were found in earlier work to depend somewhat on sweep rate; these {open_quote}{open_quote}slow dynamics{close_quote}{close_quote} are now examined and quantified. We have measured slow dynamics in a 0.3 m long, 50 mm diameter bar of Berea sandstone under ambient conditions. Peak strain levels during the experiments ranged from 10{sup {minus}11} to 10{sup {minus}5} at driving frequencies near 4 kHz, the fundamental longitudinal resonance frequency of the bar. Slow dynamics begin to manifest themselves at strain amplitudes above 10{sup {minus}6} at ambient conditions and at the onset of nonlinear peak bending. Strains above this value condition the rock, altering its response for minutes to hours after the drive has been turned off. {copyright} American Geophysical Union 1996
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 435091
- Journal Information:
- Geophysical Research Letters, Vol. 23, Issue 21; Other Information: PBD: Oct 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Laboratory study of linear and nonlinear elastic pulse propagation in sandstone
Propagation of a finite-amplitude elastic pulse in a bar of Berea sandstone: A detailed look at the mechanisms of classical nonlinearity, hysteresis, and nonequilibrium dynamics: Nonlinear propagation of elastic pulse