A direct theory of affine bodies

A direct derivation of the theory of affine bodies is presented, with empha sis posed to the constitutive principles underlying the theory and to the r ole of the group of invariance of the theory (the congruences of physical s pace). To reconcile our abstract presentation with the standard one, an ide ntification procedure of the constitutive relations of an affine body from that of a three-dimensional Cauchy body is also presented. (C) 2000 Elsevie r Science Ltd, All rights reserved.