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The plasticity index is the size of the range of water contents where the soil exhibits plastic properties. The PI is the difference between the liquid and plastic limits (PI = LL-PL). Soils with a high PI tend to be clay, those with a lower PI tend to be silt, and those with a PI of 0 (non-plastic) tend to have little or no silt or clay.
Though the exact cause of shear thinning is not fully understood, it is widely regarded to be the effect of small structural changes within the fluid, such that microscale geometries within the fluid rearrange to facilitate shearing. [6]
Greenwood and Williamson [31] defined a dimensionless parameter called the plasticity index that could be used to determine whether contact would be elastic or plastic. The Greenwood-Williamson model requires knowledge of two statistically dependent quantities; the standard deviation of the surface roughness and the curvature of the asperity peaks.
Figure 1. Bingham Plastic flow as described by Bingham. Figure 1 shows a graph of the behaviour of an ordinary viscous (or Newtonian) fluid in red, for example in a pipe. If the pressure at one end of a pipe is increased this produces a stress on the fluid tending to make it move (called the shear stress) and the volumetric flow rate increases proportionally.
Figure 1: View of Drucker–Prager yield surface in 3D space of principal stresses for =, =. The Drucker–Prager yield criterion [1] is a pressure-dependent model for determining whether a material has failed or undergone plastic yielding.
In materials science, Schmid's law (also Schmid factor [a]) describes the slip plane and the slip direction of a stressed material, which can resolve the most shear stress. ...
This plot shows a typical meridional profile of several plasticity models: von Mises, linear Drucker–Prager, Mohr–Coulomb, Gurson, and Bigoni–Piccolroaz. The upper portion of the plot depicts yield surface behavior in triaxial extension and the lower portion depicts yield surface behavior in triaxial compression.
The Hill yield criterion developed by Rodney Hill, is one of several yield criteria for describing anisotropic plastic deformations.The earliest version was a straightforward extension of the von Mises yield criterion and had a quadratic form.