Full-field Ultrahigh-speed Quantification of Dynamic Shear Ruptures Using Digital Image Correlation
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In this article, the authors report on their dynamic full-field measurements of displacement, velocities, strains and strain rates associated with the spontaneous propagation of shear ruptures in the laboratory earthquake setup.Abstract:
Producing dynamic ruptures in the laboratory allows us to study fundamental characteristics of interface dynamics. Our laboratory earthquake experimental setup has been successfully used to reproduce a number of dynamic rupture phenomena, including supershear transition, bimaterial effect, and pulse-like rupture propagation. However, previous diagnostics, based on photoelasticity and laser velocimeters, were not able to quantify the full-field behavior of dynamic ruptures and, as a consequence, many key rupture features remained obscure. Here we report on our dynamic full-field measurements of displacement, velocities, strains and strain rates associated with the spontaneous propagation of shear ruptures in the laboratory earthquake setup. These measurements are obtained by combining ultrahigh-speed photography with the digital image correlation (DIC) method, enhanced to capture displacement discontinuities. Images of dynamic shear ruptures are taken at 1-2 million frames/s over several sizes of the field of view and analyzed with DIC to produce a sequence of evolving full-field maps. The imaging area size is selected to either capture the rupture features in the far field or to focus on near-field structures, at an enhanced spatial resolution. Simultaneous velocimeter measurements on selected experiments verify the accuracy of the DIC measurements. Owing to the increased ability of our measurements to resolve the characteristic field structures of shear ruptures, we have recently been able to observe rupture dynamics at an unprecedented level of detail, including the formation of pressure and shear shock fronts in viscoelastic materials and the evolution of dynamic friction.read more
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References
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Book
Image Correlation for Shape, Motion and Deformation Measurements: Basic Concepts,Theory and Applications
TL;DR: In this paper, a comprehensive overview of image correlation for shape, motion and deformation measurements is provided. But, the authors do not discuss the effect of out-of-plane motion on 2D measurements.
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TL;DR: In this article, basic elastodynamic solutions for a stationary crack and asymptotic fields near a moving crack tip are presented. But they do not consider the elasticity and rate effects during crack growth.
Journal ArticleDOI
Determination of displacements using an improved digital correlation method
TL;DR: An improved digital correlation method is presented for obtaining the full-field in-plane deformations of an object by numerically correlating a selected subset from the digitized intensity pattern of the undeformed object.
Journal ArticleDOI
Laboratory-derived friction laws and their application to seismic faulting
TL;DR: In this article, a review of the relationship between friction and the properties of earthquake faults is presented, as well as an interpretation of the friction state variable, including its interpretation as a measure of average asperity contact time and porosity within granular fault gouge.
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Heating and weakening of faults during earthquake slip
TL;DR: In this article, the authors suggest that the most relevant weakening processes in large crustal events are thermal, and to involve thermal pressurization of pore fluid within and adjacent to the deforming fault core, which reduces the effective normal stress and hence also the shear strength for a given friction coefficient.