Smart materials have force-length similarities to human skeletal muscle (Klute et al). The development of such materials is based upon theoretical models used to predict force, length and velocity relationships (Klute). In the recent past, motors, hydraulics and engines have been used to replicate the motions of the human form in artificial limbs and robots. Because of their high weight, bulky size, and inefficient use of energy, these devices are impractical for use in a small sized machines, say, human sized or smaller. The use of these smart materials, with their small size/weight ratio, provides more efficient energy and vertical functionality. A viable replacement for a human muscle may not be far off. Artificial limbs that are stronger, faster and more flexible than anything available will make many debilitating disabilities a thing of the past.

There is a wide body of literature describing the behavior of a tendon under load. Some investigators have removed structural characteristics by reporting stress versus strain, while others have reported the form in which the data was recorded, namely forces versus elongation. The stress versus strain curve of a tendon exhibits a region where stress increases slowly with strain at first. Further strain results in more rapid increases in stress followed by a region where stress increases linearly with strain until failure.

TENSION		breaking point
tension= stretching force	linear elastic deformation...................... plastic deformation DELTA L (deformation)