Effect Of Simple Shear Research Articles

Investigation of regularities of variations in the structure of metal under simple shear

The effect of simple shear on the structure and properties of metals and alloys subjected to forging is considered. An analysis of the results of the investigation the structure of the material, which was carried out for samples of defined configuration, showed that the treatment of metal under conditions of the development of shear deformations across the workpiece section causes an intense decrease in the grain size.

Erratum: Effect of simple shear on liquid drainage within foams [Phys. Rev. E73, 061408 (2006)

Erratum: Effect of simple shear on liquid drainage within foams [Phys. Rev. E<b>73</b>, 061408 (2006)

Effect of simple shear on liquid drainage within foams

This paper examines the impact of shear on the drainage of liquid through a foam. The effect on drainage of changes in the Plateau border network brought about by shear is examined. This effect of shear was modeled using both a detailed three-dimensional simulation of foam structure, and an idealized two-dimensional hexagonal foam. The main phenomenon that has been discovered is that shear induces an anisotropy in the drainage of liquid through the foam. If the foam is strained and liquid flows under gravity either perpendicular or parallel to the shear direction, a net liquid flow in the direction perpendicular to the direction of gravity is induced. It was found that the degree of anisotropy increases nearly linearly with increasing strain until the foam yields, after which the degree of flow anisotropy remains roughly constant. This is not a small effect, with the flow in the direction perpendicular to gravity being up to about 20% of the flow in the direction of gravity at the yield strain. This shear-induced anisotropy provides a potential explanation for the hitherto puzzling phenomenon of the convective roll in foam. The other two effects examined are the effect of shear on the length of Plateau borders per volume of foam, which increases as strain increases, and the resistance of the foam to flow in the direction of gravity, which increases if the strain direction is perpendicular to gravity, but decreases if the strain is parallel to gravity.

4116 線形剪断流中に置かれた角柱の周囲流れのPIV解析(G05-10 複雑流の光学的可視化計測,G05 流体工学)

Simple shear flow was generated by using a multi-fan type wind tunnel. With the shear parameter β ranging 0.0275-0.11, the effect of simple shear on the flow around rectangular cylinders was investigated. The depth-to-height ratio was varied in a range of d/h=0.2-3.0. The flow was visualized using the same wind tunnel. We also carried out PIV mesurements in a water tank. For the case of d/h&ge;2.0 with β=0.092, the time-averaged reattachment of separeted shear layer occurred on the high-speed side.

Rheology of a two-phase material with applications to partially molten rocks, plastic deformation and saturated soils

Abstract A global model is presented to account for the specific rheology of a two-phase material. Examples of observations are taken from a crystallizing magma and these are applied to a partially molten rock, plastic deformation and soil liquefaction. The general behaviour of the viscosity is drawn as a function of the strain rate and the amount of solid phase. It constitutes a 3D diagram developing a cubic surface. The cubic equation is justified by thermodynamic considerations. It results from the mixing of a Newtonian ( n = 1) and a power law ( n = 3) type of deformation. The diagram shows two types of rheological response. At high strain rate values, the viscosity contrast between the two phases is the lowest. The resulting en masse behaviour is observed during tectonic activity. It manifests itself by homogeneous transport of magma during emplacement and fabric development. An equivalent medium, with average viscosity is a good proxy. Conversely, at low strain rate values, the viscosity contrast between the two phases is the highest. The two end members behave according to their respective rheology. In between, a transitional state develops, in which instability occurs depending on the strain rate and stress conditions. In the 3D diagram it appears as a cusp shape. Rheology presents continuous jumps between the liquid-like and the solid-like rheology. They result in strain localization or phase segregation. The latter preferentially develops during magma crystallization. Deformation under a constant amount of each phase is also possible, resulting in pressure dissolution-like processes. A bifurcation in the solution plane of the equation of viscous motion causes instability. It is comparable with strain softening. A similar situation should develop when mixing Newtonian and power law rheology, for example during diffusion and dislocation creep, or water-saturated sediment deformation. Owing to the continual jumps between the two types of rheology, hysteresis or memory effect may develop. Rapid cyclic deformation may drive strain to extreme straining. The effect of simple shear seems much more effective than pure shear (compaction) to separate the weak phase from its strong matrix. The development of instabilities and continuous jumps from one rheology to the other lead to discontinuous motion of the weak phase. In a molten region, it corresponds to discontinuous bursts of magma that are extracted.

Reflection and transmission of plane waves at a shear-twin interface

This paper is concerned with the effect of simple shear on the reflection and transmission of plane waves at the boundary between two half-spaces of incompressible elastic material, and, in particular, two half-spaces which form a twin in the sense that equal and opposite simple shears are applied to the two half-spaces. The objective is to simulate the (plastic) deformation associated with the twinning of crystals and thereby to provide a theoretical framework for the non-destructive evaluation of twinned interfaces. For a special class of constitutive laws it is shown that an incident plane harmonic (shear) wave propagating in the plane of shear in one half-space gives rise to an interfacial wave in each half-space in addition to a reflected and a transmitted plane wave in the respective half-spaces for every angle of incidence, although the amplitudes of the waves may vanish at certain discrete angles (different for each type of wave) depending on the state of deformation. For a specific material not in this special class, corresponding calculations for a particular value of shear show that the nature of the resulting waves is similar to that for the special class of materials. On the other hand, we note that for values of the shear beyond a certain critical value there are certain ranges of angles of incidence for which, instead, two homogeneous plane (shear) waves are reflected and also two transmitted. The dependence of the amplitudes of the reflected, transmitted and interfacial waves on the angle of incidence, the magnitude of the shear strain and the material properties is illustrated graphically.

Light-scattering properties of undiluted human blood subjected to simple shear.

An experimental investigation was performed into the effect of simple shear on the light-scattering properties of undiluted human blood. Undiluted human blood was enclosed between two glass plates with an adjustable separation between 30 and 120 microns and with one plate moving parallel to the other. For various shear rates and layer thicknesses, the angular light distribution and the collimated transmission were measured for 633-nm light. For shear rates above 150 s-1, the transmission results directly yielded a total attenuation coefficient of 120 mm-1. At lower shear rates the total attenuation followed an irregular pattern. From the angular intensity distributions, the anisotropy for single scattering was deduced by inverse Monte Carlo simulations. A continuous increase of the average cosine g with the shear rate was observed, with g in the range 0.95-0.975.

The Surface Evolver and the stability of liquid surfaces

The Surface Evolver is an interactive program for studying the shapes of liquid surfaces. Recently added features permit the calculation of the Hessian matrix of second derivatives of the energy. The Hessian can be used for fast convergence to an equilibrium, and eigenvalue analysis of the stability of that equilibrium. This paper describes the use of the Hessian by the Surface Evolver, presents some sample stability analyses, and gives some numerical results on the accuracy and convergence of the methods. It is also shown how one can evolve unstable surfaces.