STRAIN MEASURES, INTEGRABILITY CONDITION AND FRAME INDIFFERENCE IN THE THEORY OF ORIENTED MEDIA

This paper is concerned with the appropriate choice of state variables within the continuum model or oriented media. It is shown that residu al deformation, strain and wryness can be considered as such quantitie s. The compatibility conditions for them are derived, which make the i nverse problem of determining the displacement and director triad fiel ds well-posed. The principle of frame indifference justifies the use o f these quantities as stale variables in the free energy density. Gove rning and constitutive equations are studied in detail. A comparison w ith the continuum model of crystals with continuously distributed disl ocations is provided. (C) 1997 Elsevier Science Ltd.