This paper proposes a new approach for the analysis of shear-induced volume change of granular materials. Following a revisit to the micro-mechanical deformation mechanism and the ˆndings from discrete element method simulations, it is concluded that the double slip-rotation rate mechanism is appropriate for the description of granular materials subjected to shear. The implementation of energy ...

Fault slip distributions provide important insight into the earthquake process. We analyze high-resolution along-strike co-seismic slip profiles of the 1992 Mw = 7.3 Landers and 1999 Mw = 7.1 Hector Mine earthquakes, finding a spatial correlation between fluctuations of the slip distribution and geometrical fault structure. Using a spectral analysis, we demonstrate that the observed variation o...

While propagation of dislocations in body centered cubic metals at low temperature is understood in terms of elementary steps on {110} planes, slip traces correspond often with other crystallographic or non-crystallographic planes. In the past, characterization of slip was limited to post-mortem electron microscopy and slip trace analysis on the sample surface. Here with in-situ Laue diffractio...

A single contact point model was implemented in the open-source dynamics engine Chrono to provide a more accurate calculation of input slip quantities to the Magic Formula equations for non steady-state, or transient, slip cases. The model is formulated using a consistent ISO z-up x-forward coordinate frame, where the slip angle was shown to be invariant with the choice of coordinate system, bu...

"Walking-Mode Maps", based on Slip/Non-Slip criteria, are proposed. Slip/Non-Slip criteria are expressed as follows: for a slip to occur: |F(h)/F(n)|(h) > or = mu(s) or |F(h)/F(n)|(t) > or = mu(s); for no slip to occur: |F(h)/F(n)|(h) < mu(s) or |F(h)/F(n)|(t) < mu(s). |F(h)/F(n)|(h) and |F(h)/F(n)|(t) are the maximum peak value of the traction coefficient at heel-strike and toe-off respectivel...

We demonstrate a rupture front focusing phenomenon at the initial stage of earthquake, which causes high slip rate pulses and therefore generates high frequency seismic waves. In this computation, we assume a pre-slip region, where stress has already lowered quasi-statically to the dynamic friction level. And due to the pre-slip, we suppose a stress concentration at the edge of pre-slip area. T...

Understanding the physics of earthquake slip helps to improve seismic hazard predictions. The occurrence of quenched frictional melts along exhumed fault zones (pseudotachylytes) provides unequivocal evidence of ancient seismic slip along these faults [Sibson, 1975]. In order to better understand the evolution of friction (the ratio of shear stress over normal stress) during meltgenerating slip...

Experiments were performed in a sliding plate rheometer with a high density polyethylene to determine the conditions for the onset of slip and the relationship between slip velocity and shear stress. It was found that melt slip occurs at a critical shear stress of approximately 0.09 MPa in both steady and transient shear tests. The effect of the presence of a layer of fluorocarbon at the interf...