Seminar - Yixiang Gan - Formation of Pseudotachylytes: A Study using Meltable Discrete Element Method

Wednesday 7th September 2011, 1.00 pm - 2.00 pm
Lecture Room 3, School of Civil Engineering

Dr Yixiang Gan
Particles &Grains Laboratory, School of Civil Engineering

Abstract:
Pseudotachylyte is a fault rock that records ancient earthquakes and provides information of those seismic events, such as the magnitudes and associated displacements. Field evidences from pseudotachylyte faults have disclosed cyclical episodes of frictional melting, ductile deformations, overprinted at a later stage by a new generation of pseudotachylytes. Here we connect these cycles to earthquake dynamics using a development of discrete element model (Meltable-DEM) with solid grains that can melt during frictional heating and viscous melts that can bond through solidification during cooling. A new earthquake episode initiates with the crushing of bonded clusters once the bond strength is exceeded, with frictional shear heating being activated again. We explore the competitions between melting and solidification in terms of phase transitions using scaling laws dependent on the characteristic times for melting, thermal diffusion, and loading rates. Some other applications of Meltable-DEM will also be discussed.

Biography:
Yixiang received his Bachelor and Master degrees from Xi'an Jiaotong University, China, in 2002 and 2005, and Dr.-Ing in mechanical engineering from Karlsruhe Institute of Technology (KIT), Germany, in 2008. Then he worked as a research associate at KIT for one and half years to develop predictive tools for functional materials in the experimental nuclear fusion reactor (ITER project). He has been working as a postdoctoral fellow at The University of Sydney since May 2010.