U. Introduction In Doyle and Bricksen [1956. p. 77] it is observed that the Cauchy stress tensor 0 can be derived by varying the internal energy e with respect to the Riemannian metric on space: oab =Zpae/agab. Their formula has gone virtually unnoticed in the elasticity literature. In this lecture we shall explain some of the reasons why this formula is, in fact, of fundamental significance. S...
