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Octahedral plane 1 11 in .NET Add Code 39 Extended in .NET Octahedral plane 1 11

Octahedral plane 1 11 generate, create code 39 none with .net projects GS1 Barcodes Knowledge The ow law The most commonly used ow law for ice is Glen s ow law, named after John W. Glen upon whose experiments it is based (Glen, 1955). We will normally write Glen s ow law in the form he originally used:.

e = e B (2.15). where B is a viscosity .NET USS Code 39 parameter that increases as the ice becomes stiffer, and n is an empirically determined constant. Most studies have found that n 3.

At very low stresses, however, there is some evidence that n 1. An alternative form of the ow law that is commonly used is:. e = A en (2.16). Figure 2.7. A plane th bar code 39 for .

NET at intersects the x-, y-, and z-axes at points equidistant from the origin, in this case a unit distance, is called the octahedral plane. If similar planes are drawn involving the negative directions along the axes, the solid gure formed is a regular octahedron..

Here, B is normally gi ven in MPa a1/n , while A is in MPa n a 1 or kPa n s 1 . If the octahedral shear stress and strain rate are used, the numerical values of B and A must be adjusted accordingly, but the units stay the same..

Some basic concepts Both forms of the ow law have their advantages, and as A = (1/B)n it is easy to convert between the two forms as long as n is known. The form e = A en resembles conventional constitutive relations in rheol ogy, and is also easier to generalize if greater precision is needed in situations involving complicated stress con gurations (Glen, 1958). For example, some materials, when subjected to a shear stress, swell or contract perpendicular to the plane of shear.

In other words, deformation occurs in directions in which the stress is zero. Such rheologies require an extra term in the ow law, and this is more readily accommodated with a ow law of the form e = A en . So far, however, the forms presented in Equations (2.

16) and (2.17) seem adequate to represent phenomena observed in studies of ice deformation, both in the laboratory and on glaciers, so the additional term is not needed. The form e = ( e /B)n is similar to that used in uid mechanics with the viscosity, , de ned by:.

= du dz (2.17). Here is the shear st ress. Thus B, like , is a ratio of stress to strain rate. An increase in B results in a decrease in strain rate.

Scientists interested in geomorphological applications of glaciological principles are more likely to be familiar with principles of uid mechanics than with those of rheology, so the form e = ( e /B)n is used throughout this book. In 9, we will show that if the principle axes of stress and strain rate coincide, as is normally the case, the ow law can be written as:. i j = en 1 Bn i barcode 39 for .NET j (2.18).

where i and j can repr esent x or y or z. Eliminating e from Equations (2.15) and (2.

18) yields:. i j = e n B ij (2.19). Equation (2.18) re-emp 3 of 9 barcode for .NET hasizes a fundamental tenet of Glen s ow law mentioned above: namely that the strain rate in a given direction is a function not only of the stress in that direction, but also of all of the other stresses acting on the medium.

Equation (2.19) shows that we can express this concept in terms of strain rates, which are generally easier to measure than stresses. In the next several chapters we will be dealing with situations in which it is feasible to assume that one stress so dominates all of the others that the others can be neglected.

However, the reader should be aware of the implications of this assumption..
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