Related papers: Dislocation interactions in olivine control postse…
The rheological behaviour of olivine deforming by dislocation creep controls geodynamic processes that involve steady-state flow or transient viscosity evolution. Longstanding rheological models applied to both contexts assume that…
To examine the microstructural evolution that occurs during transient creep, we deformed olivine aggregates to different strains that spanned the initial transient deformation. Two sets of samples with different initial grain sizes of 5…
The strength of the lithosphere is typically modelled based on constitutive equations for steady-state flow. However, models of lithospheric flexure reveal differences in lithospheric strength that are difficult to reconcile based on such…
Olivine is the dominant mineral in Earth's upper mantle and therefore controls mantle rheology and the mechanics of plate tectonics. The constitutive laws for dislocation-mediated deformation of olivine depend on the nature, density, and…
The grain size of olivine influences mass and heat flux in Earth's upper mantle. We performed annealing experiments on synthetic olivine-pyroxene aggregates (6-13 vol.%) at 1-12 GPa and 1323-1793 K. Grain-size analysis via EBSD reveal an…
The thermally activated motion of dislocations across fields of obstacles distributed at random and in a correlated manner, in separate models, is studied by means of computer simulations. The strain rate sensitivity and strength are…
The flow of Earth's upper mantle has long been considered to occur by slow and near-continuous creep. Such behaviour is observed in classical high-temperature deformation experiments and is a fundamental component of geodynamic models.…
Sloped terrains tend to creep downward over time, even when their slope is below the nominal angle of repose. This behavior can result from periodic variations in environmental conditions, such as daily or seasonal fluctuations in…
A continuum theory based on thermodynamics has been developed for modeling diffusional creep of polycrystalline solids. It consists of a coupled problem of vacancy diffusion and mechanics where the vacancy generation/absorption at grain…
Deep-focus earthquakes that occur at 350-660 km, where pressures 12-23 GPa and temperature 1800-2000 K, are generally assumed to be caused by olivine-spinel phase transformation (PT). However, there are many existing puzzles: (a) What are…
To explore the role of the olivine grain size and crystal preferred orientation (CPO) on the evolution of the microstructure and the mechanical behaviour of upper mantle rocks up to large strains, we performed axial extension experiments at…
Thermomechanical processes such as fatigue and shock have been suggested to cause and contribute to rock breakdown on Earth, and on other planetary bodies, particularly airless bodies in the inner solar system. In this study, we modeled…
We investigate the depinning transition occurring in dislocation assemblies. In particular, we consider the cases of regularly spaced pileups and low angle grain boundaries interacting with a disordered stress landscape provided by solute…
Olivine comprises approximately 70 $\%$ by volume of the Earth's upper mantle, making it likely that it controls the mechanical, electrical and seismic properties of the upper mantle. All rocks are composed of crystals separated by grain…
Disordered materials under an imposed forcing can display creep and aging effects, accompanied by intermittent, spatially heterogeneous dynamics. We propose a unifying microscopic description of these phenomena, based on the notion that as…
Pinning interaction between a screw dislocation and a void in fcc copper is investigated by means of molecular dynamics simulation. A screw dislocation bows out to undergo depinning on the original glide plane at low temperatures, where the…
A certain appeal to the alpha model for turbulence and related viscosity in accretion disks was that one scales the Reynolds stresses simply on the thermal pressure, assuming that turbulence driven by a certain mechanism will attain a…
The dynamics of dislocation assemblies in deforming crystals indicate the emergence of collective phenomena, intermittent fluctuations and strain avalanches. In polycrystalline materials, the understanding of plastic deformation mechanisms…
We investigate the down-hill creep of a layer of granular material on a slope caused by an oscillatory variation of the size of the particles. The material is modeled as an athermal two dimensional polydisperse system of soft disks under…
Polycrystalline materials have a viscoelastic rheology where the strains produced by stresses depend on the timescale of deformation. Energy can be stored elastically within grain interiors and dissipated by a variety of different…