International
Tables for
Crystallography
Volume D
Physical properties of crystals
Edited by A. Authier

International Tables for Crystallography (2006). Vol. D, ch. 1.3, p. 74

Figure 1.3.1.3 

A. Authiera* and A. Zarembowitchb

aInstitut de Minéralogie et de la Physique des Milieux Condensés, Bâtiment 7, 140 rue de Lourmel, 75015 Paris, France, and bLaboratoire de Physique des Milieux Condensés, Université P. et M. Curie, 75252 Paris CEDEX 05, France
Correspondence e-mail:  aauthier@wanadoo.fr

[Figure 1.3.1.3]
Figure 1.3.1.3

Quadric of elongations. The displacement vector, [{\bf u}({\bf r})], at P in the deformed medium is parallel to the normal to the quadric at the intersection, p, of OP with the quadric. (a) The eigenvalues all have the same sign, the quadric is an ellipsoid. (b) The eigenvalues have mixed signs, the quadric is a hyperboloid with either one sheet (shaded in light grey) or two sheets (shaded in dark grey), depending on the sign of the constant [\varepsilon] [see equation (1.3.1.7)[link]]; the cone asymptote is represented in medium grey. For a practical application, see Fig. 1.4.1.1[link] .