Title: Mapping out the glassy landscape of a mesoscopic elastoplastic model
We develop a mesoscopic model to study the plastic behavior of an amorphous material under cyclic loading. The model is depinning-like and driven by a disordered thresholds dynamics that is coupled by long-range elastic interactions. We propose a simple protocol of “glass preparation” that allows us to mimic thermalization at high temperatures as well as aging at vanishing temperature. Various levels of glass stabilities (from brittle to ductile) can be achieved by tuning the aging duration. The aged glasses are then immersed into a quenched disorder landscape and serve as initial configurations for various protocols of mechanical loading by shearing. The dependence of the plastic behavior upon monotonous loading is recovered. The behavior under cyclic loading is studied for different ages and system sizes. The size and age dependence of the irreversibility transition is discussed. A thorough characterization of the disorder-landscape is achieved through the analysis of the transition graphs, which describe the plastic deformation pathways under athermal quasi-static shear. In particular, the analysis of the stability ranges of the strongly connected components of the transition graphs reveals the emergence of a phase-separation like process associated with the aging of the glass. Increasing the age and, hence, the stability of the initial glass results in a gradual break-up of the landscape of dynamically accessible stable states into three distinct regions: one region centered around the initially prepared glass phase and two additional regions characterized by well-separated ranges of positive and negative plastic strains, each of which is accessible only from the initial glass phase by passing through the stress peak in the forward and backward, respectively, shearing directions.
The temperature dependence of the thermal conductivity of amorphous solids is markedly different from that of their crystalline counterparts, but exhibits universal behaviour. Sound attenuation is believed to be related to this universal behaviour. Recent computer simulations demonstrated that in the harmonic approximation sound attenuation Γ obeys quartic, Rayleigh scattering scaling for small wavevectors k and quadratic scaling for wavevectors above the Ioffe–Regel limit. However, simulations and experiments do not provide a clear picture of what to expect at finite temperatures where anharmonic effects become relevant. Here we study sound attenuation at finite temperatures for model glasses of various stability, from unstable glasses that exhibit rapid aging to glasses whose stability is equal to those created in laboratory experiments. We find several scaling laws depending on the temperature and stability of the glass. First, we find the large wavevector quadratic scaling to be unchanged at all temperatures. Second, we find that at small wavevectors Γ ∼ k 1.5 for an aging glass, but Γ ∼ k 2 when the glass does not age on the timescale of the calculation. For our most stable glass, we find that Γ ∼ k 2 at small wavevectors, then a crossover to Rayleigh scattering scaling Γ ∼ k 4 , followed by another crossover to the quadratic scaling at large wavevectors. Our computational observation of this quadratic behavior reconciles simulation, theory and experiment, and will advance the understanding of the temperature dependence of thermal conductivity of glasses.
Coggon, R.M.; Teagle, D.A.H.; Sylvan, J.B.; Reece, J.; Estes, E.R.; Williams, T.J.; Christeson, G.L.(
, Proceedings of the International Ocean Discovery Program Expedition reports)
The South Atlantic Transect (SAT) is a multidisciplinary scientific ocean drilling experiment designed to investigate the evolution of the ocean crust and overlying sediments across the western flank of the Mid-Atlantic Ridge. This project comprises four International Ocean Discovery Program expeditions: fully staffed Expeditions 390 and 393 (April–August 2022) built on engineering preparations during Expeditions 390C and 395E (October–December 2020 and April–June 2021, respectively) that took place without science parties during the height of the Coronavirus Disease 2019 (COVID-19) pandemic. Through operations along a crustal flow line at ~31°S, the SAT recovered complete sedimentary sections and the upper ~40–340 m of the underlying ocean crust formed at a slow- to intermediate-spreading rate at the Mid-Atlantic Ridge over the past ~61 My. The sediments along this transect were originally spot cored more than 50 y ago during Deep Sea Drilling Project Leg 3 (December 1968–January 1969) to help verify the theories of seafloor spreading and plate tectonics.
The SAT expeditions targeted six primary sites on 7, 15, 31, 49, and 61 Ma ocean crust that fill critical gaps in our sampling of intact in situ ocean crust with regard to crustal age, spreading rate, and sediment thickness. Drilling these sites was required to investigate the history, duration, and intensity of the low-temperature hydrothermal interactions between the aging ocean crust and the evolving South Atlantic Ocean. This knowledge will improve the quantification of past hydrothermal contributions to global biogeochemical cycles and help develop a predictive understanding of the impacts of variable hydrothermal processes and exchanges. Samples from the transect of the previously unexplored sediment- and basalt-hosted deep biosphere beneath the South Atlantic Gyre are essential to refine global biomass estimates and examine microbial ecosystems' responses to variable conditions in a low-energy gyre and aging ocean crust.
The transect, located near World Ocean Circulation Experiment Line A10, provides records of carbonate chemistry and deepwater mass properties across the western South Atlantic through key Cenozoic intervals of elevated atmospheric CO2 and rapid climate change. Reconstruction of the history of the deep western boundary current and deepwater formation in the Atlantic basins will yield crucial data to test hypotheses regarding the role of evolving thermohaline circulation patterns in climate change and the effects of tectonic gateways and climate on ocean acidification.
During engineering Expeditions 390C and 395E (5 October–5 December 2020 and 6 April–6 June 2021, respectively), a single hole was cored through the sediment cover and into the uppermost rocks of the ocean crust with the advanced piston corer and extended core barrel systems at five of the six primary proposed SAT sites. Reentry systems with casing were then installed either into basement or within 10 m of basement at each of those five sites.
Expedition 390 (7 April–7 June 2022) conducted operations at three of the SAT sites, recovering 700 m of core (77% recovery) over 30.3 days of on-site operations. Sediment coring, basement coring, and wireline logging were conducted at two sites on ~61 Ma crust (Sites U1556 and U1557), and sediment coring was completed at the 7 Ma Site U1559. During Expedition 390, more than 1.2 km of sediments was characterized, including 793 m of core collected during Expeditions 390C and 395E at Sites U1556, U1557, and U1559 as well as Expedition 395E Site U1561, which was cored on thinly (<50 m) sedimented ~61 Ma crust. The uppermost ~342 and ~120 m of ~61 Ma ocean crust was cored at Sites U1556 and U1557, respectively. Geophysical wireline logging was achieved at both sites, but the basement hole at Site U1556 was not preserved as a legacy hole because of subsidence of the reentry cone below the seafloor. At Site U1557, the drill bit was deposited on the seafloor prior to downhole logging, leaving Hole U1557D available for future deepening and establishing a legacy borehole for basement hydrothermal and microbiological experiments.
Expedition 393 (7 June–7 August 2022) operated at four sites, drilling in 12 holes to complete this initial phase of the SAT. Complete sedimentary sections were collected at Sites U1558, U1583, and U1560 on 49, 31, and 15 Ma crust, respectively, and together with 257.7 m of sediments cored during earlier operations, more than 600 m of sediments was characterized. The uppermost ocean crust was drilled at Sites U1558, U1560, and U1583 with good penetration (~130 to ~204 meters subbasement); however, at the youngest ~7 Ma Site U1559, only ~43 m of basement penetration was achieved in this initial attempt. Geophysical wireline logs were achieved at Sites U1583 and U1560 only. Expeditions 390 and 393 established legacy sites available for future deepening and downhole basement hydrothermal and microbiological experiments at Sites U1557, U1560, and U1559 on 61, 15, and 7 Ma crust, respectively.
Highlights of the SAT expeditions include (1) recovering abundant altered glass, hydrothermal veins, complex breccias, and a wide range of alteration halos in the volcanic sequences of the uppermost ocean crust formed at 7–61 Ma, indicating low-temperature hydrothermal processes and exchanges between seawater and basalts across the western flank of the southern Mid-Atlantic Ridge for millions to tens of millions of years; (2) documenting extended redox gradients from both the seafloor and the sediment/basement interface that indicate significant subsurface fluid flow and may support a diversity of microorganisms and metabolisms; and (3) recovering an almost complete stratigraphic record of the Cenozoic (including the Paleocene/Eocene Thermal Maximum and other key climate events) composed of nannofossil oozes with varying amounts of clay indicating the shoaling and deepening of the calcite compensation depth.
Coggon, R.M.; Teagle, D.A.H.; Sylvan, J.B.; Reece, J.; Estes, E.R.; Williams, T.J.; Christeson, G.L.; Aizawa, M.; Albers, E.; Amadori, C.; et al(
, Proceedings of the International Ocean Discovery Program Expedition reports)
The South Atlantic Transect (SAT) is a multidisciplinary scientific ocean drilling experiment designed to investigate the evolution of the ocean crust and overlying sediments across the western flank of the Mid-Atlantic Ridge. This project comprises four International Ocean Discovery Program expeditions: fully staffed Expeditions 390 and 393 (April–August 2022) built on engineering preparations during Expeditions 390C and 395E (October–December 2020 and April–June 2021, respectively) that took place without science parties during the height of the Coronavirus Disease 2019 (COVID-19) pandemic. Through operations along a crustal flow line at ~31°S, the SAT recovered complete sedimentary sections and the upper ~40–340 m of the underlying ocean crust formed at a slow- to intermediate-spreading rate at the Mid-Atlantic Ridge over the past ~61 My. The sediments along this transect were originally spot cored more than 50 y ago during Deep Sea Drilling Project Leg 3 (December 1968–January 1969) to help verify the theories of seafloor spreading and plate tectonics.
The SAT expeditions targeted six primary sites on 7, 15, 31, 49, and 61 Ma ocean crust that fill critical gaps in our sampling of intact in situ ocean crust with regard to crustal age, spreading rate, and sediment thickness. Drilling these sites was required to investigate the history, duration, and intensity of the low-temperature hydrothermal interactions between the aging ocean crust and the evolving South Atlantic Ocean. This knowledge will improve the quantification of past hydrothermal contributions to global biogeochemical cycles and help develop a predictive understanding of the impacts of variable hydrothermal processes and exchanges. Samples from the transect of the previously unexplored sediment- and basalt-hosted deep biosphere beneath the South Atlantic Gyre are essential to refine global biomass estimates and examine microbial ecosystems' responses to variable conditions in a low-energy gyre and aging ocean crust.
The transect, located near World Ocean Circulation Experiment Line A10, provides records of carbonate chemistry and deepwater mass properties across the western South Atlantic through key Cenozoic intervals of elevated atmospheric CO2 and rapid climate change. Reconstruction of the history of the deep western boundary current and deepwater formation in the Atlantic basins will yield crucial data to test hypotheses regarding the role of evolving thermohaline circulation patterns in climate change and the effects of tectonic gateways and climate on ocean acidification.
During engineering Expeditions 390C and 395E (5 October–5 December 2020 and 6 April–6 June 2021, respectively), a single hole was cored through the sediment cover and into the uppermost rocks of the ocean crust with the advanced piston corer and extended core barrel systems at five of the six primary proposed SAT sites. Reentry systems with casing were then installed either into basement or within 10 m of basement at each of those five sites.
Expedition 390 (7 April–7 June 2022) conducted operations at three of the SAT sites, recovering 700 m of core (77% recovery) over 30.3 days of on-site operations. Sediment coring, basement coring, and wireline logging were conducted at two sites on ~61 Ma crust (Sites U1556 and U1557), and sediment coring was completed at the 7 Ma Site U1559. During Expedition 390, more than 1.2 km of sediments was characterized, including 793 m of core collected during Expeditions 390C and 395E at Sites U1556, U1557, and U1559 as well as Expedition 395E Site U1561, which was cored on thinly (<50 m) sedimented ~61 Ma crust. The uppermost ~342 and ~120 m of ~61 Ma ocean crust was cored at Sites U1556 and U1557, respectively. Geophysical wireline logging was achieved at both sites, but the basement hole at Site U1556 was not preserved as a legacy hole because of subsidence of the reentry cone below the seafloor. At Site U1557, the drill bit was deposited on the seafloor prior to downhole logging, leaving Hole U1557D available for future deepening and establishing a legacy borehole for basement hydrothermal and microbiological experiments.
Expedition 393 (7 June–7 August 2022) operated at four sites, drilling in 12 holes to complete this initial phase of the SAT. Complete sedimentary sections were collected at Sites U1558, U1583, and U1560 on 49, 31, and 15 Ma crust, respectively, and together with 257.7 m of sediments cored during earlier operations, more than 600 m of sediments was characterized. The uppermost ocean crust was drilled at Sites U1558, U1560, and U1583 with good penetration (~130 to ~204 meters subbasement); however, at the youngest ~7 Ma Site U1559, only ~43 m of basement penetration was achieved in this initial attempt. Geophysical wireline logs were achieved at Sites U1583 and U1560 only. Expeditions 390 and 393 established legacy sites available for future deepening and downhole basement hydrothermal and microbiological experiments at Sites U1557, U1560, and U1559 on 61, 15, and 7 Ma crust, respectively.
Highlights of the SAT expeditions include (1) recovering abundant altered glass, hydrothermal veins, complex breccias, and a wide range of alteration halos in the volcanic sequences of the uppermost ocean crust formed at 7–61 Ma, indicating low-temperature hydrothermal processes and exchanges between seawater and basalts across the western flank of the southern Mid-Atlantic Ridge for millions to tens of millions of years; (2) documenting extended redox gradients from both the seafloor and the sediment/basement interface that indicate significant subsurface fluid flow and may support a diversity of microorganisms and metabolisms; and (3) recovering an almost complete stratigraphic record of the Cenozoic (including the Paleocene/Eocene Thermal Maximum and other key climate events) composed of nannofossil oozes with varying amounts of clay indicating the shoaling and deepening of the calcite compensation depth.
Rollo, Fabio; Buscarnera, Giuseppe(
, International Journal for Numerical and Analytical Methods in Geomechanics)
Abstract
Landslide motion is often simulated with interface‐like laws able to capture changes in frictional strength caused by the growth of the pore water pressure and the consequent reduction of the effective stress normal to the plane of sliding. Here it is argued that, although often neglected, the evolution of all the 3D stress components within the basal shear zone of landslides also contributes to changes in frictional strength and must be accounted for to predict changes in seasonal velocity. For this purpose, an augmented sliding‐consolidation model is proposed which allows for the computation of excess pore pressure development and downslope sliding with any constitutive law with 3D stress evolution. Simulations of idealised infinite slope models subjected to hydrologic forcing are used to study the role of in‐situ stress conditions and stress rate multiaxiality. Specifically, a Drucker‐Prager perfectly plastic model is used to replicate frictional failure and shear deformation at the base of landslides. The model reveals that conditions amenable to the shearing of a frictional interface are met only after numerous rainfall cycles, that is, when multiaxial stress rates are suppressed. In this case, the landslide is predicted to move through a seasonal ratcheting controlled only by the effective stress component normal to the plane of sliding. By contrast, in newly formed landslides, the multiaxial stress evolution is found to produce further regimes of motion, from plastic shakedown to cyclic failure, neither of which can be captured by interface‐like frictional laws. Notably, the model suggests that a transition across these regimes can emerge in response to an aggravation of the magnitude of forcing, implying that (i) fluctuations in climate may alter the seasonal trends of motion observed today; (ii) our ability to quantify landslide‐induced risks is impaired unless proper geomechanical models are used to examine their long‐term dynamics.
Pattern switching (or transformation) widely exists in the activities of various creatures and plays an important role in designing adaptive structures in modern materials. Utilizing the glass transition behavior in amorphous polymers, thermomechanically triggered two‐stage pattern switching of 2D lattices is achieved, where components made of an amorphous polymer and a flexible elastomer are interconnected in predesigned layouts. Upon loading at room temperature, the elastomer is far more flexible than the amorphous polymer and the lattice switches into one pattern. With temperature increasing, the modulus of the amorphous polymer decreases due to glass transition. Under the proper choice of amorphous polymer whose storage modulus can decrease to below the modulus of the elastomer, a change in the relative stiffness can be achieved and can switch the overall pattern from one to another while maintaining the external load. Both the experimental and computational studies are carried out to investigate the switching mechanism. Several periodic structures are fabricated to demonstrate several switched patterns. Particularly, a proof‐of‐concept smart window design is fabricated to explore the potential engineering applications.
Kumar, D., Patinet, S., Maloney, C. E., Regev, I., Vandembroucq, D., and Mungan, M. Mapping out the glassy landscape of a mesoscopic elastoplastic model. The Journal of Chemical Physics 157.17 Web. doi:10.1063/5.0102669.
Kumar, D., Patinet, S., Maloney, C. E., Regev, I., Vandembroucq, D., & Mungan, M. Mapping out the glassy landscape of a mesoscopic elastoplastic model. The Journal of Chemical Physics, 157 (17). https://doi.org/10.1063/5.0102669
Kumar, D., Patinet, S., Maloney, C. E., Regev, I., Vandembroucq, D., and Mungan, M.
"Mapping out the glassy landscape of a mesoscopic elastoplastic model". The Journal of Chemical Physics 157 (17). Country unknown/Code not available: American Institute of Physics. https://doi.org/10.1063/5.0102669.https://par.nsf.gov/biblio/10378202.
@article{osti_10378202,
place = {Country unknown/Code not available},
title = {Mapping out the glassy landscape of a mesoscopic elastoplastic model},
url = {https://par.nsf.gov/biblio/10378202},
DOI = {10.1063/5.0102669},
abstractNote = {We develop a mesoscopic model to study the plastic behavior of an amorphous material under cyclic loading. The model is depinning-like and driven by a disordered thresholds dynamics that is coupled by long-range elastic interactions. We propose a simple protocol of “glass preparation” that allows us to mimic thermalization at high temperatures as well as aging at vanishing temperature. Various levels of glass stabilities (from brittle to ductile) can be achieved by tuning the aging duration. The aged glasses are then immersed into a quenched disorder landscape and serve as initial configurations for various protocols of mechanical loading by shearing. The dependence of the plastic behavior upon monotonous loading is recovered. The behavior under cyclic loading is studied for different ages and system sizes. The size and age dependence of the irreversibility transition is discussed. A thorough characterization of the disorder-landscape is achieved through the analysis of the transition graphs, which describe the plastic deformation pathways under athermal quasi-static shear. In particular, the analysis of the stability ranges of the strongly connected components of the transition graphs reveals the emergence of a phase-separation like process associated with the aging of the glass. Increasing the age and, hence, the stability of the initial glass results in a gradual break-up of the landscape of dynamically accessible stable states into three distinct regions: one region centered around the initially prepared glass phase and two additional regions characterized by well-separated ranges of positive and negative plastic strains, each of which is accessible only from the initial glass phase by passing through the stress peak in the forward and backward, respectively, shearing directions.},
journal = {The Journal of Chemical Physics},
volume = {157},
number = {17},
publisher = {American Institute of Physics},
author = {Kumar, D. and Patinet, S. and Maloney, C. E. and Regev, I. and Vandembroucq, D. and Mungan, M.},
}
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