scholarly journals Diffraction of shear plane electroelastic wave on the semi-infinite electrode in the piezoelectric space with crack.

2010 ◽  
Vol 63 (1) ◽  
pp. 50-69
Author(s):  
K.L. Aghayan ◽  
E.Kh. Grigoryan
Keyword(s):  
Shear Plane ◽  
Electroelastic Wave

scholarly journals An X-ray CT study of miniature clay sample preparation techniques

2019 ◽  
Vol 92 ◽  
pp. 01004
Author(s):  
Christopher Ibeh ◽  
Matteo Pedrotti ◽  
Alessandro Tarantino ◽  
Rebecca Lunn
Keyword(s):  
Sample Preparation ◽  
Shear Plane ◽  
Cohesive Soil ◽  
Image Resolution ◽  
Particle Orientation ◽  
X Ray ◽  
High Resolution Images ◽  
X Ray Computed ◽  
Sample Disturbance ◽  
Relationship Of

The quality and reliability of cohesive soil laboratory test data can be significantlyaffected by sample disturbance during sampling or sample preparation. Sample disturbance may affect key design and modelling parameters such as stiffness, preconsolidation stress, compressibility and undrained shear strength, and ultimately determine particle mobilization and shear plane development. The use of X-ray computed tomography (X-CT) in the study of soil is restricted by the inverse relationship of specimen size and obtainable image resolution. This has led to the testing of miniature specimen sizes which are far less than conventional laboratory sample size in a bid to obtain high resolution images and detailed particle-scale soil properties; however, these miniature soil specimens are more prone to sample disturbance. In this work 2% muscovite was mixed with speswhite kaolin clay as a strain marker for use in X-CT. The clay soil sample was prepared from slurry and either consolidated using an oedometer or a gypsum mould. Specimens obtained from a 7 mm tube sampler were compared to lathe trimmed specimens with a diameter (Ø) of 7 mm. Results from X-CT imaging were used to study the influence of sampler type on specimen disturbance, by analysing the muscovite particle orientation of the obtained 3D images. The results show that; for samples subjected to large consolidation stress (>200kpa) lathe trimmed specimens may be subject to lesser disturbance compared to tube sampled specimens.

scholarly journals Investigation of a cold-based ice apron on a high-mountain permafrost rock wall using ice texture analysis and micro-14C dating: a case study of the Triangle du Tacul ice apron (Mont Blanc massif, France)

2021 ◽  
pp. 1-8
Author(s):  
Grégoire Guillet ◽  
Susanne Preunkert ◽  
Ludovic Ravanel ◽  
Maurine Montagnat ◽  
Ronny Friedrich
Keyword(s):  
Radiocarbon Dating ◽  
Boundary Migration ◽  
Ice Core ◽  
Ice Cores ◽  
Shear Plane ◽  
High Mountain ◽  
14C Dating ◽  
Rock Wall ◽  
Major Mechanism ◽  
Mont Blanc Massif

Abstract The current paper studies the dynamics and age of the Triangle du Tacul (TDT) ice apron, a massive ice volume lying on a steep high-mountain rock wall in the French side of the Mont-Blanc massif at an altitude close to 3640 m a.s.l. Three 60 cm long ice cores were drilled to bedrock (i.e. the rock wall) in 2018 and 2019 at the TDT ice apron. Texture (microstructure and lattice-preferred orientation, LPO) analyses were performed on one core. The two remaining cores were used for radiocarbon dating of the particulate organic carbon fraction (three samples in total). Microstructure and LPO do not substantially vary with along the axis of the ice core. Throughout the core, irregularly shaped grains, associated with strain-induced grain boundary migration and strong single maximum LPO, were observed. Measurements indicate that at the TDT ice deforms under a low strain-rate simple shear regime, with a shear plane parallel to the surface slope of the ice apron. Dynamic recrystallization stands out as the major mechanism for grain growth. Micro-radiocarbon dating indicates that the TDT ice becomes older with depth perpendicular to the ice surface. We observed ice ages older than 600 year BP and at the base of the lowest 30 cm older than 3000 years.

scholarly journals Design of plate and screw anchors in dense sand: failure mechanism, capacity and deformation

2019 ◽  
Vol 92 ◽  
pp. 16010
Author(s):  
Benjamin Cerfontaine ◽  
Jonathan Knappett ◽  
Michael Brown ◽  
Aaron Bradshaw
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Failure Mechanism ◽  
Progressive Failure ◽  
Vertical Direction ◽  
Shear Plane ◽  
Design Methods ◽  
Embedment Depth ◽  
Limiting State ◽  
Dense Sand

Plate and screw anchors provide a significant uplift capacity and have multiple applications in both onshore and offshore geotechnical engineering. Uplift design methods are mostly based on semi-empirical approaches assuming a failure mechanism, a normal and a shear stress distribution at failure and empirical factors back-calculated against experimental data. However, these design methods are shown to under- or overpredict most of the existing larger scale experimental tests. Numerical FE simulations are undertaken to provide new insight into the failure mechanism and stress distribution which should be considered in anchor design in dense sand. Results show that a conical shallow wedge whose inclination to the vertical direction is equal to the dilation angle is a good approximation of the failure mechanism in sand. This shallow mechanism has been observed in each case for relative embedment ratios (depth/diameter) ranging from 1 to 9. However, the stress distribution varies non-linearly with depth, due to the soil deformability and progressive failure. A sharp peak of normal and shear stress can be identified close to the anchor edge, before a gradual decrease with increasing distance along the shear plane. The peak stress magnitude increases almost linearly with embedment depth at larger relative embedment ratios. Although further research is necessary, these results lay the basis for the development of a new generation of design criteria for determining anchor capacity at the ultimate limiting state.

Position of Shear Plane at the Clay-Water Interface: Strong Polarization Effects of Counterions

2017 ◽  
Vol 81 (2) ◽  
pp. 268-276 ◽  
Author(s):  
Xinmin Liu ◽  
Wuquan Ding ◽  
Rui Tian ◽  
Wei Du ◽  
Hang Li
Keyword(s):  
Shear Plane ◽  
Water Interface ◽  
Polarization Effects ◽  
Strong Polarization

Dynamics of a non-spherical microcapsule with incompressible interface in shear flow

2011 ◽  
Vol 678 ◽  
pp. 221-247 ◽  
Author(s):  
P. M. VLAHOVSKA ◽  
Y.-N. YOUNG ◽  
G. DANKER ◽  
C. MISBAH
Keyword(s):  
Shear Rate ◽  
Shear Flow ◽  
Viscosity Ratio ◽  
Perturbation Expansion ◽  
Shear Plane ◽  
Creeping Flow ◽  
Regular Perturbation ◽  
Cell Dynamics ◽  
Initial Shape ◽  
Flow Equations

We study the motion and deformation of a liquid capsule enclosed by a surface-incompressible membrane as a model of red blood cell dynamics in shear flow. Considering a slightly ellipsoidal initial shape, an analytical solution to the creeping-flow equations is obtained as a regular perturbation expansion in the excess area. The analysis takes into account the membrane fluidity, area-incompressibility and resistance to bending. The theory captures the observed transition from tumbling to swinging as the shear rate increases and clarifies the effect of capsule deformability. Near the transition, intermittent behaviour (swinging periodically interrupted by a tumble) is found only if the capsule deforms in the shear plane and does not undergo stretching or compression along the vorticity direction; the intermittency disappears if deformation along the vorticity direction occurs, i.e. if the capsule ‘breathes’. We report the phase diagram of capsule motions as a function of viscosity ratio, non-sphericity and dimensionless shear rate.

A Suggested Origin of Continental Slopes and of Submarine Canyons

1950 ◽  
Vol 87 (2) ◽  
pp. 102-104 ◽  
Author(s):  
K. O. Emery
Keyword(s):  
Sea Level ◽  
Shear Plane ◽  
Continental Margins ◽  
Submarine Canyons ◽  
Continental Shelves ◽  
Continental Slopes

AbstractThrusting along a shear plane at the continental margins may result in a temporary up-bulging of the margins above sea-level. During the time of exposure erosion by streams should have incised canyons which now, after isostatic readjustment of the margins, constitute the widely distributed submarine canyons. Known downwarped peneplains below the surface of continental shelves may have been developed on the bulged margins by long continued erosion. The margins may, thus, have served as- sources of some sediments now found on land and believed to have been derived from a seaward direction.

Assessment of instability initiation in exposed salt rock roofs

2021 ◽  
pp. 34-38
Author(s):  
D. N. Shkuratskiy ◽  
D. S. Chernopazov ◽  
I. B. Vaulina
Keyword(s):  
Damage Zone ◽  
Shear Plane ◽  
Plane Elasticity ◽  
Mining Operations ◽  
Support Design ◽  
Salt Rocks ◽  
Main Requirement ◽  
Potash Salt ◽  
Failure Conditions ◽  
Coulomb Criterion

Stability of rocks is the main requirement for the safe operation of mines. For this purpose, certain measures are applied for the protection and support of underground openings, including roof support design and roof arrangement in the most stable rocks. Stability assessment of underground excavations is largely related to their roof stability. Determination of possible instability conditions in mine roofs governs the choice of support system design and parameters of mine excavations. The Upper Kama Potash Salt Deposit represents a stratified layer of solid salt rocks. Roof instability develops as stratification and roof collapse. The Mohr–Coulomb criterion of coherent rocks is currently used to estimate parameters of a possible damage zone in the exposed roof. This criterion allows evaluating shear plane angles in roof rocks and, as a result, finding parameters of the possible collapse zone. The experience of mining operations in the Upper Kama deposit shows different failure conditions as against the Mohr–Coulomb criterion as the stress state is scarcely included in the criterion used. This study is an attempt to assess parameters of rock exposures by solving a Lame problem in terms of a single mine excavation. The analytical results were compared with the parameters obtained from the plane elasticity solutions by the finite element method. Based on the implemented studies, an engineering approach is developed for the assessment of anticipated instability parameters in exposed roofs in horizontal excavations driven in salt rocks.

scholarly journals Electric double layer and electrokinetic potential of pectic macromolecules in sugar beet

2008 ◽  
pp. 21-28
Author(s):  
Tatjana Kuljanin ◽  
Ljubinko Levic ◽  
Nevena Misljenovic ◽  
Gordana Koprivica
Keyword(s):  
Sugar Beet ◽  
Double Layer ◽  
Electric Double Layer ◽  
Colloidal Particles ◽  
Colloidal Particle ◽  
Electrokinetic Potential ◽  
Shear Plane ◽  
Colloidal System ◽  
Cu Ions ◽  
Measurable Property

Electrokinetic potential is an important property of colloidal particles and, regarding the fact that it is a well defined and easily measurable property, it is considered to be a permanent characteristic of a particular colloidal system. In fact, it is a measure of electrokinetic charge that surrounds the colloidal particle in a solution and is in direct proportion with the mobility of particles in an electric field. Gouy-Chapman-Stern-Graham's model of electric double layer was adopted and it was proven experimentally that the addition of Cu++ ions to sugar beet pectin caused a reduction in the negative electrokinetic potential proportional to the increase of Cu++ concentration. Higher Cu++ concentrations increased the proportion of cation specific adsorption (Cu++ and H+) with regard to electrostatic Coulombic forces. Consequently, there is a shift in the shear plane between the fixed and diffuse layers directed towards the diffuse layer, i.e. towards its compression and decrease in the electrokinetic potential or even charge inversion of pectin macromolecules.

Microstructural Characterization of Chip Segmentation Under Different Machining Environments in Orthogonal Machining of Ti6Al4V

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Shashikant Joshi ◽  
Asim Tewari ◽  
Suhas S. Joshi
Keyword(s):  
Plastic Strain ◽  
Room Temperature ◽  
Microstructural Analysis ◽  
Cutting Speed ◽  
Microstructural Characterization ◽  
Shear Plane ◽  
Band Formation ◽  
Orthogonal Machining ◽  
Two Temperatures ◽  
Experimental Values

Segmented chips are known to form in machining of titanium alloys due to localization of heat in the shear zone, which is a function of machining environment. To investigate the correlation between machining environments and microstructural aspects of chip segmentation, orthogonal turning experiments were performed under three machining environments, viz., room, LN2, and 260 °C. Scanning electron and optical microscopy of chip roots show that the mechanism of chip segment formation changes from plastic strain and mode II fracture at room temperature, to predominant mode I fracture at LN2 and plastic strain leading to shear band formation at 260 °C. The chip segment pitch and shear plane length predicted using Deform™ matched well with the experimental values at room temperature. The microstructural analysis of chips show that higher shear localization occurs at room temperature than the other two temperatures. The depth of machining affected zone (MAZ) on work surfaces was lower at the two temperatures than that of at the room temperature at a higher cutting speed of 91.8 m/min.

scholarly journals Bending Behaviour of Dowelled Mortise and Tenon Joints in Kempas

2008 ◽  
Vol 5 (1) ◽  
pp. 1 ◽  
Author(s):  
Rohana Hassan ◽  
Azmi Ibrahim ◽  
Zakiah Ahmad
Keyword(s):  
Load Capacity ◽  
Plastic Hinge ◽  
Shear Plane ◽  
Strength Properties ◽  
Visual Observation ◽  
Tropical Timber ◽  
Wood Dowel ◽  
Bending Load ◽  
Timber Connections ◽  
Mortise And Tenon

Mortise and tenon are commonly used as timber connections between beam and column with enhancement by pultruded dowel. At present the data on the performance of mortise and tenon joints manufactured using Malaysian tropical timber is not available. Therefore there is a need to provide such data for better guidance and references in design purposes. This study investigates the behavior and strength properties of dowelled mortise and tenon timber connections using selected Malaysian tropical timber with different types of dowels namely steel and timber. Bending tests were performed on mortise and tenon beam-column joints of Kempas when plugged with steel or wood dowel. It is found that pegging the connections with the respective steel and timber dowels resulted in a bending load capacity of 6.09 and 5.32 kN, taken as the average of three samples, the latter being 12 % lower than former. Visual observation of the failed test pieces revealed steel dowels exhibiting yield mode Im and wood, mode IIIs. The wood dowels yielded in bending at one plastic hinge point per shear plane with an associated wood crushing while the steel dowels remained practically undeformed with an associated crushing of the main member.

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