Spontaneous Thermal Runaway as an Ultimate Failure Mechanism of Materials

Braeck, S.; Podladchikov, Y. Y.

doi:10.1103/physrevlett.98.095504

Cited by 103 publications

(88 citation statements)

References 19 publications

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“…Accordingly, to obtain the conditions for spontaneous runaway modes, one should analyze the case in which the initial perturbation T 0 itself becomes a steady state and therefore choose T ss ≈ T 0 in Eq. (36). This yields the equation…”

Section: Conditions For Thermal Runaway the General Casementioning

confidence: 92%

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Spontaneous dissipation of elastic energy by self-localizing thermal runaway

2009

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Thermal runaway instability induced by material softening due to shear heating represents a potential mechanism for mechanical failure of viscoelastic solids. In this work we present a model based on a continuum formulation of a viscoelastic material with Arrhenius dependence of viscosity on temperature, and investigate the behavior of the thermal runaway phenomenon by analytical and numerical methods. Approximate analytical descriptions of the problem reveal that onset of thermal runaway instability is controlled by only two dimensionless combinations of physical parameters. Numerical simulations of the model independently verify these analytical results and allow a quantitative examination of the complete time evolutions of the shear stress and the spatial distributions of temperature and displacement during runaway instability. Thus we find that thermal runaway processes may well develop under nonadiabatic conditions. Moreover, nonadiabaticity of the unstable runaway mode leads to continuous and extreme localization of the strain and temperature profiles in space, demonstrating that the thermal runaway process can cause shear banding. Examples of time evolutions of the spatial distribution of the shear displacement between the interior of the shear band and the essentially nondeforming material outside are presented. Finally, a simple relation between evolution of shear stress, displacement, shear-band width and temperature rise during runaway instability is given.

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Section: Conditions For Thermal Runaway the General Casementioning

confidence: 92%

“…[36]. Our model is based on a simple continuum formulation of a viscoelastic medium, i.e., the rheology contains both viscous and elastic components.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous dissipation of elastic energy by self-localizing thermal runaway

2009

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“…In that formulation the heat generated by plastic work raises the thermal/kinetic temperature, instead of the configurational/effective temperature. Lewandowski and Greer [31] have shown that in a bulk metallic glass the thermal temperature diffuses too quickly to control shear localization in an adiabatic description, though Braeck and Podladchikov [32] have shown that a non-adiabatic thermal theory can explain the data.…”

Section: Introductionmentioning

confidence: 99%

Strain localization in a shear transformation zone model for amorphous solids

2007

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We model a sheared disordered solid using the theory of Shear Transformation Zones (STZs). In this mean-field continuum model the density of zones is governed by an effective temperature that approaches a steady state value as energy is dissipated. We compare the STZ model to simulations by Shi, et al.[Y. Shi et al. PRL 98, 185505 (2007)], finding that the model generates solutions that fit the data, exhibit strain localization, and capture important features of the localization process. We show that perturbations to the effective temperature grow due to an instability in the transient dynamics, but unstable systems do not always develop shear bands. Nonlinear energy dissipation processes interact with perturbation growth to determine whether a material exhibits strain localization. By estimating the effects of these interactions, we derive a criterion that determines which materials exhibit shear bands based on the initial conditions alone. We also show that the shear band width is not set by an inherent diffusion length scale but instead by a dynamical scale that depends on the imposed strain rate.

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“…[4] An alternative mechanism invokes the presence of highly localized viscous creep leading to increases in temperature, weakening, and further slip in a narrow shear zone-a positive feedback mechanism referred to as a thermal shear instability [Keleman and Hirth, 2007;Braeck and Podladchikov, 2007;Houston, 2007;John et al, 2009]. Laboratory experiments of frictional properties at seismic slip velocities [Di Toro et al, 2006;Del Gaudio et al, 2009;Di Toro et al, 2011] and field observations of mafic and ultramafic rocks in subduction settings [Obata and Karato, 1995;Ueda et al, 2008] both show evidence of extremely high temperatures in the form of pseudotachylites, which are glassy veins formed by fast melting during seismic slip.…”

Section: Introductionmentioning

confidence: 99%

Seismic evidence for thermal runaway during intermediate‐depth earthquake rupture

Prieto

Florez

Barrett

et al. 2013

Geophysical Research Letters

109

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[1] Intermediate-depth earthquakes occur at depths where temperatures and pressures exceed those at which brittle failure is expected. There are two leading candidates for the physical mechanism behind these earthquakes: dehydration embrittlement and self-localizing thermal shear runaway. A complete energy budget for a range of earthquake sizes can help constrain whether either of these mechanisms might play a role in intermediate-depth earthquake rupture. The combination of high stress drop and low radiation efficiency that we observe for M w 4-5 earthquakes in the Bucaramanga Nest implies a temperature increase of 600-1000°C for a centimeter-scale layer during earthquake failure. This suggests that substantial shear heating, and possibly partial melting, occurs during intermediate-depth earthquake failure. Our observations support thermal shear runaway as the mechanism for intermediate-depth earthquakes, which would help explain differences in their behavior compared to shallow earthquakes. Citation: Prieto, G. A., M. Florez, S. A. Barrett, and G. C. Beroza (2013), Seismic evidence for thermal runaway during intermediate-depth earthquake rupture, Geophys. Res. Lett., 40,[6064][6065][6066][6067][6068]

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Spontaneous Thermal Runaway as an Ultimate Failure Mechanism of Materials

Cited by 103 publications

References 19 publications

Spontaneous dissipation of elastic energy by self-localizing thermal runaway

Spontaneous dissipation of elastic energy by self-localizing thermal runaway

Strain localization in a shear transformation zone model for amorphous solids

Seismic evidence for thermal runaway during intermediate‐depth earthquake rupture

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