Mechanical instabilities of smectic-A liquid crystals under dilative or compressive stresses

Abstract

Résumé. 2014

Numerical study of stretched smectic-Aelastomer sheets

“…At larger strain this degeneracy is removed and bidirectional modulation is lower in energy. This theory of bidirectional buckling is consistent with experiments on liquid smectics, where two directions of buckling are observed in x-ray-scattering patterns [3]. The layer buckling is relaxed away in liquid smectics by the propagation of dislocations into the layers that relieve the strain.…”

Undulation instability in stripe domain structures of « bubble » material

“…To quadratic order in u, expression (12) [7] and is illustrated in figure 3 Consequently, a x-deformation corresponds to a pure rotation and does not involve additional energy. A true x-deformation is therefore aulax -1/2 ( au/ay ) 2 and expression (13) must be modified and reads up to third order in u : This is precisely the form obtained directly in equation (12) for q = qo within the phase approximation (11).…”

“…This type of Hamiltonian is well known in the context of smectic A elasticity and is responsible for the undulation instability occurring under extensional strain [7]. Below [2] and outlined in equation (1) (2) and (3) yielding equations (6) and (7) where only local correlations are described.…”

Self-Organized Periodic Photonic Structure in a Nonchiral Liquid Crystal

“…In chiral liquid crystals the competition between the favored twist state due to the chiral characteristics and the uniform state due to the applied electric or magnetic field or geometic constraints often causes the formation of periodic frustration structures [3]. However, there appears to be no mention of a frustration structure for the case of nonchiral liquid crystals even though there are many theoretical and experimental studies [4][5][6][7][8] concerning defect structures of smectic liquid crystals.…”