THE RELATIONSHIP BETWEEN GRAIN SHAPE AND CRYSTALLOGRAPHIC ORIENTATION OF QUARTZ PORPHYROCLASTS FROM A MID-CRUSTAL SHEAR ZONE, ROCKFISH VALLEY DEFORMATION ZONE, VIRGINIA

2016 ◽  
Author(s):  
Jenna Biegel ◽  
◽  
Jeffrey M. Rahl
Keyword(s):  
Shear Zone ◽  
Crystallographic Orientation ◽  
Deformation Zone ◽  
Grain Shape ◽  
The Relationship

scholarly journals Review of the relationship between aggregates geology and Los Angeles and micro-Deval tests

2021 ◽  
Vol 80 (3) ◽  
pp. 1963-1980
Author(s):  
Solomon Adomako ◽  
Christian John Engelsen ◽  
Rein Terje Thorstensen ◽  
Diego Maria Barbieri
Keyword(s):  
Los Angeles ◽  
Crystal Size ◽  
Grain Shape ◽  
Mechanical Performance ◽  
Pore Space ◽  
Construction Material ◽  
Engineering Properties ◽  
Coarse Grained ◽  
The Impact ◽  
The Relationship

AbstractRock aggregates constitute the enormous volume of inert construction material used around the globe. The petrologic description as igneous, sedimentary, and metamorphic types establishes the intrinsic formation pattern of the parent rock. The engineering properties of these rocks vary due to the differences in the transformation process (e.g. hydrothermal deposits) and weathering effect. The two most common mechanical tests used to investigate the performance of aggregates are the Los Angeles (LA) and micro-Deval (MD) tests. This study reviewed the geological parameters (including mineralogy, grain and crystal size, grain shape, and porosity) and the relationship to Los Angeles and micro-Deval tests. It was found that high content of primary minerals in rocks (e.g. quartz and feldspar) is a significant parameter for performance evaluation. Traces of secondary and accessory minerals also affect the performance of rocks, although in many cases it is based on the percentage. Furthermore, some studies showed that the effect of mineralogic composition on mechanical strength is not sufficient to draw final conclusions of mechanical performance; therefore, the impact of other textural characteristics should be considered. The disposition of grain size and crystal size (e.g. as result of lithification) showed that rocks composed of fine-grain textural composition of ≤ 1 mm enhanced fragmentation and wear resistance than medium and coarse grained (≥ 1 mm). The effect of grain shape was based on convex and concave shapes and flat and elongated apexes of tested samples. The equidimensional form descriptor of rocks somehow improved resistance to impact from LA than highly flat and elongated particles. Lastly, the distribution of pore space investigated by means of the saturation method mostly showed moderate (R = 0.50) to strong (R = 0.90) and positive correlations to LA and MD tests.

TiO2 mesocrystals built of nanocrystals with exposed {001} facets: facile synthesis and superior photocatalytic ability

2014 ◽  
Vol 2 (46) ◽  
pp. 19589-19593 ◽  
Author(s):  
Yanna Guo ◽  
Hui Li ◽  
Jin Chen ◽  
Xuejing Wu ◽  
Lei Zhou
Keyword(s):  
Photocatalytic Activity ◽  
Specific Surface ◽  
Crystallite Size ◽  
Surface Area ◽  
Crystallographic Orientation ◽  
Low Cost ◽  
Facile Synthesis ◽  
Photocatalytic Ability ◽  
Similar Crystallographic Orientation ◽  
The Relationship

A totally novel, extremely easy, much greener and low-cost method has been developed to synthesize TiO2 mesocrystals. These materials are built of TiO2 nanocrystals with similar crystallographic orientation and largely exposed {001} facets. Their unique structure optimizes the relationship between specific surface area, crystallite size and active facets, and therefore leads to superior photocatalytic activity.

The Influence of Friction Coefficient on Tenon/Groove Contact Performance in Nickel-Based Turbine Blade-Disc

2014 ◽  
Vol 940 ◽  
pp. 74-80 ◽  
Author(s):  
Guo Cai Zhou ◽  
Zhi Xun Wen ◽  
Zhu Feng Yue ◽  
Yu Fen Gao
Keyword(s):  
Fatigue Life ◽  
Friction Coefficient ◽  
Contact Stress ◽  
Crystallographic Orientation ◽  
Contact Region ◽  
Complex Loading ◽  
Plastic Slip ◽  
Rate Dependent ◽  
Stress Fatigue ◽  
The Relationship

This paper presented the influence of crystallographic orientation and friction coefficient on the contact stress and fatigue life in the tenon/groove contact region. A rate-dependent crystallographic plastic slip theory was used to calculate the contact stress and fatigue life in [001], [011] and [111] orientations. In the calculation, complex loading conditions and different friction coefficients of 0, 0.2, 0.4, 0.6, 0.8 and 1.0 were taken into account in tenon/groove. Then the relationship between contact stress, fatigue life and friction coefficient was discussed. Simulation results show that: friction coefficient and crystallographic orientation have significant effect on contact stress and fatigue life. Contact stress in [001], [011] and [111] orientation increases with increasing friction coefficient generally. For [001] and [011] orientation, the fatigue life decreases with increasing friction coefficient firstly. When friction coefficient is 0.4, the fatigue life meets its minimum. Then the fatigue life will increase with increasing friction coefficient. For [111] orientation, the change of fatigue life has no obvious trend, and while friction coefficient exceeds 0.6, the life almost constant.

Geochronological evidence for repeated brittle reactivations of a pre-existing plastic shear zone: The Himdalen–Ørje deformation zone, Southern Norway

2021 ◽  
Author(s):  
Espen Torgersen ◽  
Roy Gabrielsen ◽  
Johan Petter Nystuen ◽  
Roelant van der Lelij ◽  
Morgan Ganerød ◽  
...  
Keyword(s):  
Shear Zone ◽  
Deformation Zone ◽  
Shear Zones ◽  
White Mica ◽  
Fault Gouge ◽  
Plastic Shear ◽  
Brittle Deformation ◽  
Sveconorwegian Orogen ◽  
Fault Gouges ◽  
Southern Norway

<p>It is well known that faults, once formed, become permanent weaknesses in the crust, localizing subsequent brittle strain increments. The case of repeated brittle reactivations localized along pre-existing plastic shear zones is less recognized, although this situation is frequently observed in many geologically old terranes.</p><p>We have studied the prolonged deformation history of the Himdalen–Ørje Deformation Zone (HØDZ) in SE Norway by combining K–Ar and <sup>40</sup>Ar–<sup>39</sup>Ar geochronology with structural analysis. The HØDZ consists of a large variation of deformation products from mylonites and cataclasites to pseudotachylites and fault gouge. Several generations of mylonites make up the ductile part of HØDZ, called the Ørje shear zone, a km-think SW-dipping shear zone within the late Mesoproterozoic Sveconorwegian orogen. <sup>40</sup>Ar–<sup>39</sup>Ar dating of white mica from one of these mylonites give a plateau age of c. 908 Ma, interpreted to constrain the timing of late-Sveconorwegian extensionial reactivation of the Ørje shear zone.</p><p>This mylonitic fabric is extensively reworked in a brittle fashion along the SW-dipping Himdalen fault, a 10–25 m thick fault zone of cataclasite, breccia, fault gouge and, in places, abundant pseduotachylite veins. <sup>40</sup>Ar–<sup>39</sup>Ar dating of pseduotachylite material gives several small plateaus between c. 375 and 300 Ma, whereas K-feldspar clasts from the cataclasitically deformed host rock carry a Caledonian signal (plateau at c. 435 Ma). K–Ar dating of three fault gouges constrain the timing of gouge development at c. 270 and 200 Ma. Two of the fault gouges also contain protolithic K-bearing mineral phases that overlap in age with the c. 375 Ma pseudotachylite <sup>40</sup>Ar–<sup>39</sup>Ar plateau age, consistent with field observations of the former reworking the latter.</p><p>In sum, the HØDZ records multiple Paleozoic and Mesozoic brittle reactivations of the early Neoproterozoic (and older) mylonitic Ørje shear zone. Most of the brittle deformation is interpreted to have accumulated during development of the Permian Oslo rift and its subsequent latest Triassic evolution. The suggested late Devonian (c. 375 Ma) initiation of brittle deformation does not have a clear tectonic association, but we speculate that it relates to strike-slip displacements caused by the Variscan orogen, as also suggested for the sub-parallel Tornquist zone to the south.</p>

The analytic study on the heavy steel plate snake rolling with the different roll diameters

2019 ◽  
Vol 116 (4) ◽  
pp. 402 ◽  
Author(s):  
Qing-cheng Meng ◽  
Lian-yun Jiang ◽  
Li-feng Ma ◽  
Jun-yi Lei
Keyword(s):  
Shear Zone ◽  
Deformation Zone ◽  
Steel Plate ◽  
Rolling Force ◽  
Slip Zone ◽  
Mechanical Parameters ◽  
Rolling Method ◽  
Rolling Torque ◽  
Inner Region ◽  
Rolling Deformation

The deformation in the inner region along the thickness of the heavy steel plate can be improved by snake rolling method. Then the microstructure and property will be refined and the crack in the inner region may be avoided. So the in-depth research on snake rolling method mechanics parameter modeling should be conducted to guide production. The rolling deformation zone will be divided into back slip zone, cross shear zone, front slip zone and reverse deflection zone according to the direction of the friction during the snake rolling process. The four zones may not exist at the same time. The boundary conditions of existence of the back slip zone, cross shear zone and front slip zone were established by calculating the position of neutral point by a special method. The calculating models which were used to calculate the snake rolling mechanical parameters including the rolling force and rolling torque were setup. The calculated models of unit compressive pressure in the four zones were setup by the slab method, and at this basis, the accurate calculating models of the rolling force and rolling torque were setup according to the composition of the rolling deformation zone and the boundary condition. The mechanical parameters were calculated by the analytic method and the numerical method, and the relative deviation is less than 5% which can satisfy the industrial requirement. The present analytical model can predict the characteristics during snake rolling easily and quickly and it is also suitable for online control applications.

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