Stem Tilt in the Contact Plane of Epitaxially Grown Polylactide Lamellae and Its Direct Correlation with Lamellar Bending

2011 ◽  
Vol 44 (11) ◽  
pp. 4335-4341 ◽  
Author(s):  
Feng-Der Wang ◽  
Jrjeng Ruan ◽  
Yi-Fang Huang ◽  
An-Chung Su
Keyword(s):  
Contact Plane

scholarly journals Хаотический потенциал заряженных дислокаций в гетероконтактах III-нитридов

2021 ◽  
Vol 47 (1) ◽  
pp. 12
Author(s):  
В.Б. Бондаренко ◽  
А.В. Филимонов ◽  
Ravi Kumar
Keyword(s):  
Electrostatic Field ◽  
Dielectric Response ◽  
Spatial Dispersion ◽  
Electron Gas ◽  
Surface States ◽  
Two Dimensional ◽  
Dimensional Electron ◽  
Two Dimensional Electron Gas ◽  
Contact Plane ◽  
Dimensional Electron Gas

In this work, the structure of the chaotic potential in heterocontacts of III-nitrides, caused by the electrostatic field of charged dislocations, is studied. Taking into account the spatial dispersion of the dielectric response of a two-dimensional electron gas, the amplitude and scale of the chaotic potential in the contact plane are determined. The dependence of the parameters of the chaotic potential on the surface states density and the concentration of dislocations is shown.

Multidigit Control of Contact Forces During Transport of Handheld Objects

2007 ◽  
Vol 98 (2) ◽  
pp. 851-860 ◽  
Author(s):  
Sara A. Winges ◽  
John F. Soechting ◽  
Martha Flanders
Keyword(s):  
Contact Force ◽  
Muscle Activity ◽  
Center Of Mass ◽  
Contact Forces ◽  
Load Force ◽  
Emg Activity ◽  
Experimental Conditions ◽  
Contact Plane ◽  
Grasping Forces ◽  
Grasp Stability

When an object is lifted vertically, the normal force increases and decreases in tandem with tangential (load) force to safely avoid slips. For horizontal object transport, horizontal forces at the contact surfaces can be decomposed into manipulation forces (producing acceleration/deceleration) and grasping forces. Although the grasping forces must satisfy equilibrium constraints, it is not clear what determines their modulation across time, nor the extent to which they result from active muscle contraction or mechanical interactions of the digits with the moving object. Grasping force was found to increase in an experimental condition where the center of mass was below the contact plane, compared with when it was in the contact plane. This increase may be aimed at stabilizing object orientation during translation. In another experimental condition, more complex moments were introduced by allowing the low center of mass to swing around a pivot point. Electromyographic (EMG) activity recorded from several intrinsic and extrinsic hand muscles failed to reveal active feedback regulation of contact force in this situation. Instead, in all experimental conditions, EMG data revealed a strategy of feedforward stiffness modulation. Multiple regression analysis revealed that muscle activity at remote digits (e.g., the index and ring fingers) was highly correlated with the contact force measured at another digit (e.g., the thumb). The data suggest that to maintain grasp stability during horizontal translation, predictable as well as somewhat unpredictable inertial forces are compensated for by controlling the stiffness of the hand through cocontraction and modulation of hand muscle activity.

scholarly journals Stress Tensor and Gradient of Hydrostatic Pressure in the Contact Plane of Axisymmetric Bodies Under Normal and Tangential Loading

2020 ◽  
Author(s):  
Emanuel Willert ◽  
Fabian Forsbach ◽  
Valentin L. Popov
Keyword(s):  
Hydrostatic Pressure ◽  
Stress Tensor ◽  
Normal Component ◽  
Hertzian Contact ◽  
Von Mises Stress ◽  
Axially Symmetric ◽  
Principal Stresses ◽  
Contact Plane ◽  
Stress Components ◽  
Von Mises

The Hertzian contact theory, as well as most of the other classical theories of normal and tangential contact, provides displacements and the distribution of normal and tangential stress components directly in the contact surface. However, other components of the full stress tensor in the material may essentially influence the material behaviour in contact. Of particular interest are principal stresses and the equivalent von Mises stress, as well as the gradient of the hydrostatic pressure. For many engineering and biomechanical problems, it would be important to find these stress characteristics at least in the contact plane. In the present paper, we show that the complete stress state in the contact plane can be easily found for axially symmetric contacts under very general assumptions. We provide simple explicit equations for all stress components and the normal component of the gradient of hydrostatic pressure in the form of one-dimensional integrals.

Prediction of Resonant Response of Shrouded Blades With 3D Shroud Constraint

1998 ◽  
Author(s):  
B. D. Yang ◽  
J. J. Chen ◽  
C. H. Menq
Keyword(s):  
Relative Motion ◽  
Normal Load ◽  
Three Dimensional ◽  
Force Model ◽  
Resonant Response ◽  
Equivalent Stiffness ◽  
Stick Slip ◽  
Contact Plane ◽  
Blade System ◽  
Stiffness And Damping

In this paper, the 3D shroud contact kinematics of a shrouded blade system is studied. The assumed blade motion has three components, namely axial, tangential, and radial components, which result in a three dimensional relative motion across the shroud interface. The resulting relative motion can be decomposed into two components. The first one is on the contact plane and can induce stick-slip friction. The other component is perpendicular to the contact plane and can cause variation of the contact normal load and, in extreme circumstances, separation of the two contacting surfaces. In order to estimate the equivalent stiffness and damping of the shroud contact an approach is proposed. In this approach, the in-plane slip motion is assumed to be elliptical and is decomposed into two linear motions along the principal major and minor axes of the ellipse. A variable normal load friction force model (Yang and Menq, 1996) is then applied separately to each individual linear motion, and the equivalent stiffness and damping of the shroud contact can be approximately estimated. With the estimated stiffness and damping, the developed shroud contact model is applied to the prediction of the resonant response of a shrouded blade system. The effects of two different shroud constraint conditions, namely 2D constraint and 3D constraint, on the resonant response of a shrouded blade system are compared and the results are discussed.

Glacier movement, ice structures, and medial moraine form at a glacier confluence, Berendon Glacier, British Columbia, Canada

1977 ◽  
Vol 14 (12) ◽  
pp. 2807-2816 ◽  
Author(s):  
N. Eyles ◽  
R. J. Rogerson
Keyword(s):  
British Columbia ◽  
Strain Rate ◽  
Lateral Compression ◽  
Ice Streams ◽  
Glacier Surface ◽  
Ice Flow ◽  
Contact Plane ◽  
Confluence Zone ◽  
Ice Velocity ◽  
Surface Ice

On Berendon Glacier, Canada, at the asymmetric Y junction of two large valley glaciers, observations of ice velocity, strain rate, and ice structures indicate that the form of a medial moraine is determined by severe lateral compression between the two ice streams. Debris of the moraine is recycled along complex transport paths determined by ice structures. For example, supraglacial debris is precipitated into the confluence zone between the two glaciers forming a subglacial debris reservoir. Debris is evacuated from the reservoir by shearing between the two glaciers and is revealed on the glacier surface as debris dykes and melt-out tills along the contact plane. Important implications regarding the sedimentology of the moraine can be stated. Elsewhere debris is precipitated into transverse crevasses subsequently resulting in transverse till ridges at the glacier surface.Annually-formed wave ogives, bulges in surface ice, and overriding along the glacier contacts result from severe lateral compresssion, and add further diversity to the moraine.Downglacier, confluence ice structures are destroyed by ablation, the pattern of ice flow becomes less complex, unified flow between the two glaciers is established, and a distinct structurally-determined moraine morphology is replaced by one dependent upon the differential ablation of debris covered and clean ice.

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