Double-exposure PLIF imaging of compressible shear layers

A Device for Magnification Measurement

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100096369 ◽

1972 ◽

Vol 30 ◽

pp. 622-623

Author(s):

J.A. Eades ◽

A. van Dun

Keyword(s):

Electron Microscope ◽

Small Displacement ◽

Private Communication ◽

Piezoelectric Crystal ◽

Double Exposure ◽

Standard Methods ◽

Elegant Method ◽

The Right ◽

Piezo Electric

The measurement of magnification in the electron microscope is always troublesome especially when a goniometer stage is in use, since there can be wide variations from calibrated values. One elegant method (L.M.Brown, private communication) of avoiding the difficulties of standard methods would be to fit a device which displaces the specimen a small but known distance and recording the displacement by a double exposure. Such a device would obviate the need for changing the specimen and guarantee that the magnification was measured under precisely the conditions used.Such a small displacement could be produced by any suitable transducer mounted in one of the specimen translation mechanisms. In the present case a piezoelectric crystal was used. Modern synthetic piezo electric ceramics readily give reproducible displacements in the right range for quite modest voltages (for example: Joyce and Wilson, 1969).

Download Full-text

Therapist in Double Exposure

Contemporary Psychology ◽

10.1037/007350 ◽

1964 ◽

Vol 9 (1) ◽

pp. 2-3

Author(s):

FRED FOSMIRE

Keyword(s):

Double Exposure

Download Full-text

The Structures of the Shear Layers in Box Shear Test of Soil

Landslides ◽

10.3313/jls1964.31.10 ◽

1994 ◽

Vol 31 (1) ◽

pp. 10-20_1

Author(s):

Ryojiro KISHIMOTO

Keyword(s):

Shear Test ◽

Shear Layers

Download Full-text

Analysis of shear bands in slow granular flows using a frictional Cosserat model

MRS Proceedings ◽

10.1557/proc-627-bb4.3 ◽

2000 ◽

Vol 627 ◽

Author(s):

Prabhu R. Nott ◽

K. Kesava Rao ◽

L. Srinivasa Mohan

Keyword(s):

Scaling Laws ◽

Shear Bands ◽

Shear Layers ◽

Theoretical Description ◽

Field Variable ◽

Cosserat Continuum ◽

Momentum Balance ◽

Rigid Plastic ◽

Independent Field ◽

Cosserat Model

ABSTRACTThe slow flow of granular materials is often marked by the existence of narrow shear layers, adjacent to large regions that suffer little or no deformation. This behaviour, in the regime where shear stress is generated primarily by the frictional interactions between grains, has so far eluded theoretical description. In this paper, we present a rigid-plastic frictional Cosserat model that captures thin shear layers by incorporating a microscopic length scale. We treat the granular medium as a Cosserat continuum, which allows the existence of localised couple stresses and, therefore, the possibility of an asymmetric stress tensor. In addition, the local rotation is an independent field variable and is not necessarily equal to the vorticity. The angular momentum balance, which is implicitly satisfied for a classical continuum, must now be solved in conjunction with the linear momentum balances. We extend the critical state model, used in soil plasticity, for a Cosserat continuum and obtain predictions for flow in plane and cylindrical Couette devices. The velocity profile predicted by our model is in qualitative agreement with available experimental data. In addition, our model can predict scaling laws for the shear layer thickness as a function of the Couette gap, which must be verified in future experiments. Most significantly, our model can determine the velocity field in viscometric flows, which classical plasticity-based model cannot.

Download Full-text