Stored energy function Subject

Previous formulations of ruhber elasticity theory have been based on the assumption that either the defonmtion , or force field associated with crosslink deformations is the same as in a continuum. There is no apriori justification for such an assumption. In the present theory, consideration is given to a completely arbitrary distribution of crosslink deformations. Generalized equations for the six components of the macroscopic stress tensor and for the stored strain energy function are formulated. The unknown deformation functions of the radius vectors between crosslinks are then found by postulating that the deformation functions are such as to minimize the free energy of the network, subject to the constraints imposed by the macroscopic stress components applied to the body. 

Prosthetic Feet. With the exception of partial foot amputees, the prostheses for all lower extremity amputees require a prosthetic foot. The prescription criteria for these feet take into consideration the amputation level, residual limb length, subject activity level, cosmetic needs, and the weight of the individual. Prosthetic feet range from the SACK (solid ankle cushioned heel) foot, which is relatively simple and inexpensive, to dynamic-response or energy-storing feet that are more complicated and considerably more costly. Note that prosthetic feet are often foot and ankle complexes. As such, prosthetic feet may replace plantarflexion/dorsiflexion, pronation/supination, and inversion/eversion. Prosthetic feet are typically categorized in terms of the function(s) they provide or replace and whether or not they are articulated. 

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