Critical length scales and strain localization govern the mechanical performance of multi-layer graphene assemblies

Nanoscale ◽  
2016 ◽  
Vol 8 (12) ◽  
pp. 6456-6462 ◽  
Author(s):  
Wenjie Xia ◽  
Luis Ruiz ◽  
Nicola M. Pugno ◽  
Sinan Keten
Keyword(s):  
Strain Localization ◽  
Mechanical Performance ◽  
Critical Length ◽  
Deformation Mechanisms ◽  
Length Scales ◽  
Layer Graphene ◽  
Constitutive Response

Three critical length scales govern the deformation mechanisms and constitutive response of multi-layer graphene.

scholarly journals Fracture Mechanics of Human Blood Clots: Measurements of Toughness and Critical Length scales

2021 ◽  
Author(s):  
Shiyu Liu ◽  
Guangyu Bao ◽  
Zhenwei Ma ◽  
Christian Kastrup ◽  
Jianyu Li
Keyword(s):  
Fracture Mechanics ◽  
Whole Blood ◽  
Significant Contribution ◽  
Critical Length ◽  
Length Scale ◽  
Length Scales ◽  
Platelet Poor Plasma ◽  
Lap Shear ◽  
Blood Clots ◽  
Nonlinear Elastic

Blood coagulates to plug vascular damage and stop bleeding, and thus the function of blood clots in hemostasis depends on their resistance against rupture (toughness). Despite the significance, fracture mechanics of blood clots remains largely unexplored, particularly the measurements of toughness and critical length scales governing clot fracture. Here, we study the fracture behavior of human whole blood clots and platelet-poor plasma clots. The fracture energy of whole blood clots and platelet-poor plasma clots determined using modified lap-shear method is 5.90 +- 1.18 J/m2 and 0.96 +- 0.90 J/m2, respectively. We find that the measured toughness is independent of the specimen geometry and loading conditions. These results reveal a significant contribution of blood cells to the clot fracture, as well as the dissipative length scale and nonlinear elastic length scale governing clot fracture.

Textural evolution and fluid-rock interaction during upper crustal, seismic deformation: Insights from the carbonate-dominated fault rock suite of the Belluno Thrust, Italian Southern Alps

2020 ◽  
Author(s):  
Renato Diamanti ◽  
Costantino Zuccari ◽  
Selina Bonini ◽  
Gianluca Vignaroli ◽  
Giulio Viola
Keyword(s):  
Structural Characterization ◽  
Strain Localization ◽  
Hanging Wall ◽  
Damage Zone ◽  
Southern Alps ◽  
Deformation Mechanisms ◽  
Pressure Solution ◽  
Time Interval ◽  
Rock Interaction ◽  
Calcite Veins

<p>A multi-scalar, multi-methodological approach has been used to characterize the deformation mechanisms and fluid-rock interaction processes within the Belluno Thrust (BT), a regional-scale thrust cutting through Mesozoic carbonates of the eastern Southern Alps of Italy. We report the first results of a systematic analysis of the deformation mechanisms that steered strain localization within the BT fault zone during seismogenic faulting. The WSW-ENE-striking BT contributed to development of the south-verging thrust-and-fold belt of the Southern Alps during the Late Oligocene – present time interval.        We studied an outstanding exposure of the BT in the greater Feltre region, where the BT juxtaposes an Early Jurassic oolitic and micritic limestone (the Calcari Grigi Group) in the hanging wall against an Upper Jurassic-Early Cretaceous pelagic and cherty limestone (the Maiolica Fm.). The BT is defined by a 2 m-thick damage zone formed at the expense of both the hanging wall and footwall blocks. Atop the damage zone is a millimetric principal slip surface (PSS) that strikes WSW-ENE and dips 40° to the NNW. Kinematic analysis confirms the top-to-the SSE transport along the BT. Several structural facies have been identified by means of detailed structural mapping and sampled from the damage zone (from within both the hanging- and the footwall blocks) and the PSS. The outcrop structural characterization has revealed a number of physically juxtaposed, yet different, structural facies: i) cohesive, weakly foliated proto- to ultracataclasite; ii) uncohesive, clay-rich gouge; iii) foliated domains with SC-C’ structures. Relatively unstrained host rock lithons are wrapped by these variably strained domains. Petrographic and microstructural analyses show evidence of pervasive pressure solution, with abundant stylolites, slickolites and foliated domains indicating an overall ductile behaviour. Calcite veins are also common in all recognised structural facies showing mutual cross-cutting relationships with the pressure-solution seams. This structural characterization has provided the basis for detailed image analysis of selected cataclastic textures to calculate fractal parameters for the particle size distribution (Ds) and morphology (Dr) of the clasts aiming at better understanding the cataclastic flow active in the BT fault rocks. Results from a range of representative samples suggest corrosive wear to be the main cataclastic process (Ds 1,41 ÷ 2,00; Dr 1,51 ÷ 1,88). Cathodoluminescence imaging revealed multiple generations of cement and permitted discriminating the first-order chemical characteristics of parental fluids and constraining the relationships between calcite veining and cementation. Two syn-tectonic cements have been identified: i) a bright-orange cement, preferentially surrounding carbonate clasts with highly irregular margins, indicative of the involvement of carbonate-reactive fluids; ii) a dull, homogeneous brown/black cement coexisting with a siliceous matrix, mantled clasts and local sigmoidal structures. The latter is at times observed as thin injections and fluidized structures.        Our preliminary results suggest that overall deformation was accommodated by creep and low-T crystal-plastic deformation possibly during inter-seismic phases as indicated by the presence of pressure-solution seams and foliated fabrics. Transient spikes of coseismic rupturing possibly promoted by multiple batches of overpressured fluids were accompanied by significant cataclasis and brittle strain localization.</p>

scholarly journals Dominating deformation mechanisms in ultrafine-grained chromium across length scales and temperatures

2017 ◽  
Vol 140 ◽  
pp. 176-187 ◽  
Author(s):  
R. Fritz ◽  
D. Wimler ◽  
A. Leitner ◽  
V. Maier-Kiener ◽  
D. Kiener
Keyword(s):  
Deformation Mechanisms ◽  
Length Scales ◽  
Ultrafine Grained

FOLDING MECHANICS OF BI-LAYER GRAPHENE SHEET

Nano LIFE ◽  
2012 ◽  
Vol 02 (02) ◽  
pp. 1240007 ◽  
Author(s):  
ZHONG ZHOU ◽  
DONG QIAN ◽  
VIJAY K. VASUDEVAN ◽  
RODNEY S. RUOFF
Keyword(s):  
Graphene Sheet ◽  
Energy Barrier ◽  
Simulation Analysis ◽  
Critical Length ◽  
Activation Energy Barrier ◽  
Elastic Band ◽  
Layer Graphene ◽  
Nonlinear Mechanical ◽  
Dependent Potential ◽  
Plane Compression

Folding in graphene sheet has been extensively observed experimentally. While it is generally recognized that such a conformational state can influence the electronic, magnetic and mechanical properties of graphene nanostructures, the mechanism driving the nonlinear mechanical deformation remains an interesting subject of study. Here we present an investigation on the folding in bi-layer graphene sheet due to in-plane compression. To describe the lattice registry effect of interlay cohesion in layered graphitic structures, a registry-dependent potential model was implemented. We have determined the critical length to stabilize the graphene folding to be 5.4~10.7 nm through both theoretical and simulation analysis. The mechanism for such a stabilized fold is attributed to the variations in the inter-layer interaction energy that produces a friction-like effect. The climbing image nudged elastic band (CINEB) calculations predicted an identical activation energy barrier associated with the transition between flat and folded configurations, 0.47 eV/Å, for graphene sheets with length of 7~10 nm. When the mechanical stimulation is high enough to overcome the energy barrier, the supported graphene sheet can be folded to form a nanotube.

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