Simple tension with hydrostatic

If the direction of pull is denoted hy the subscript 1 and the two transverse directions by the subscripts 2 or 3 then simple tension with superimposed hydrostatic pressure is characterized by the following statement ... 

Neither of these conditions is easily maintained. In the laboratory it is easier to maintain P and one of the lengths (i ) constant. Thus in order to compute the thermostatic quantities presented in the preceding section, it is necessary to reconstruct these formulae for the case of simple tension with superimposed hydrostatic pressure. We shall not do this in general, but will present the results for one candidate strain energy density. 

The profiles of pendant and sessile bubbles and drops are commonly used in determinations of surface and interfacial tensions and of contact angles. Such methods are possible because the interfaces of static fluid particles must be at equilibrium with respect to hydrostatic pressure gradients and increments in normal stress due to surface tension at a curved interface (see Chapter 1). It is simple to show that at any point on the surface... 

The effects of surface tension on sessile and pendent drops or lenses are but a simple manifestation of capillary hydrostatics. The field of capillarity can be far more extensive, principally when coupled with electromagnetic forces and also for liquid interfaces in motion, or in the motion in liquid interfaces that may result from local variations in surface tension as may be caused, for example, by local variations in temperature, or by the localized introduction of surfactants (interfacial tension modifiers), or by localized space-delimited chemical reactions. Wicking flows (as in heat pipes ) and flows in porous media (as in petroleum reservoir displacement) are a few of many other examples in which interfacial forces play a predominant role. ... 

In order to determine which is the most appropriate yield criterion for a particular material it is necessary to follow the yield behaviour by using a variety of different combinations of multiaxial stress. However, with polymers rather unusual features are revealed when the yield stress of the same polymer is measured just in simple uniaxial tension and compression. Both the Tresca and von Mises criteria predict that the yield stress should be the same in both cases and this is what is found for metals. But for polymers the compressive yield stress is usually higher than the tensile one. This difference between the compressive and tensile yield stress can be taken as an indication that the hydrostatic component of the applied stress... 

One of the most striking effects associated with surface tension is the rise (sometimes a fall) of a liquid in a vertical tube partly immersed in it, to a height above (or below) that predicted by simple hydrostatic conditions. 

Our previous discussions [3,4] calling attention to the use of the Interaction Matrix concept dealt with associations between the chain stiffness in terms of the simple Rouse Theory and (1) the stress at a spherical flaw in a linearly incompressible viscoelastic material loaded in hydrostatic tension, and (2) cyclic fatigue life in essentially the same geometrical configuration. In the first case [3] it was shown that at the flaw radius, a, and at the time, t = Tq (the center of the transition region), for example,... 

---