HR: 14:25h
AN: V13E-04    [Abstracts]
TI: Simulations of Stiffness and Yield Stress Growth in Crystal Networks
AU: Saar, M O
EM: saar@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota-Twin Cities, Pilsbury Hall, Minneapolis, MN 55455,
AU: * Walsh, S D
EM: sdcwalsh@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota-Twin Cities, Pilsbury Hall, Minneapolis, MN 55455,
AB: Magmas experience a change in rheology from Newtonian to Bingham flow upon developing a space-spanning crystal network. The crystal volume fraction at which this transition occurs can be predicted with percolation theory; however, the manner in which the yield stress grows with increasing crystal number densities is less-well understood. This presentation discusses a simple numerical model that aims to predict the growth of yield stress in bonded crystal assemblies above (and close to) the percolation threshold. The crystal assemblies are represented by soft-core interpenetrating cuboid particles, whose mechanical properties are reproduced in a network model. The model is used to investigate the influence of particle shape and alignment anisotropy on the yield stress of crystal networks with particle volume fractions above the percolation threshold. The predictions of the model are compared with results obtained from a critical path analysis. Good agreement is found between a characteristic stiffness obtained from critical path analysis, the growth in assembly stiffness predicted by the model (both of which have approximately cubic power-law exponents) and, to a lesser extent, the growth in yield stress (with a power-law exponent of 3.5). The effects of preferred particle alignment and the presence of bubbles on the yield stress are also briefly discussed.
DE: 0545 Modeling (4255)
DE: 0560 Numerical solutions (4255)
DE: 8429 Lava rheology and morphology
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting