Monodomain liquid crystalline networks: reorientation mechanism from uniform to stripe domains

Zubarev, Eugene R.; Kuptsov, S. A.; Yuranova, T. I.; Talroze, R. V.; Finkelmann, Heino

doi:10.1080/026782999203869

Cited by 72 publications

(64 citation statements)

References 26 publications

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“…A similar program has been successfully pursued for nematic elastomers, where the free energy density is also nonconvex. The resulting theoretical predictions of microstructure [23][24][25] are in good agreement with experiment [26,27].…”

Section: Introductionsupporting

confidence: 75%

Numerical study of stretched smectic-Aelastomer sheets

Brown

Adams

2013

Phys. Rev. E

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We present a numerical study of stretching monodomain smectic-A elastomer sheets, computed using the finite element method. When stretched parallel to their smectic layer normal the smectic layers are unstable to a transition to a buckled state. We model macroscopic deformations by replacing the microscopic energy with a coarse grained effective free energy that accounts for the fine-scale layer buckling. We augment this model with a term to describe the energy of deforming buckled layers, which is necessary to reproduce the experimentally observed Poisson ratios postbuckling. We examine the spatial distribution of the microstructure phases for various stretching angles relative to the layer normal and for different length-to-width aspect ratios. When stretching parallel to the layer normal the majority of the sample forms a bidirectionally buckled microstructure, except at the clamps where a unidirectionally buckled microstructure is predicted. When stretching at small inclinations to the layer normal the phase of the sample is sensitive to the aspect ratio of the sample, with the bidirectionally buckled phase persistent to large angles only for small aspect ratios. We relate these theoretical results to experiments on smectic-A elastomers.

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Section: Introductionsupporting

confidence: 75%

Numerical study of stretched smectic-Aelastomer sheets

Brown

Adams

2013

Phys. Rev. E

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“…This has been shown by detailed x-ray experiments [8] and by numerical study [41,43], and is a result of the nonconvex energy of nematic LCEs [44]. The characteristic stress-strain response of Sm-A elastomers [12] also exhibits microstructure if the sample is clamped during stretching [45].…”

Section: Discussionmentioning

confidence: 84%

Negative Poisson's ratio and semisoft elasticity of smectic-Cliquid-crystal elastomers

Brown

Adams

2012

Phys. Rev. E

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Models of smectic-C liquid-crystal elastomers predict that they can display soft elasticity, in which the shape of the elastomer changes at no energy cost. The amplitude of the soft mode and the accompanying shears are dependent on the orientation of the layer normal and the director with respect to the stretch axis. We demonstrate that in some geometries the director is forced to rotate perpendicular to the stretch axis, causing lateral expansion of the sample-a negative Poisson's ratio. Current models do not include the effect of imperfections that must be present in the physical sample. We investigate the effect of a simple model of these imperfections on the soft modes in monodomain smectic-C elastomers in a variety of geometries. When stretching parallel to the layer normal (with imposed strain) the elastomer has a negative stiffness once the director starts to rotate. We show that this is a result of the negative Poisson's ratio in this geometry through a simple scalar model.

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“…Several experiments [42,64] report formation of microstructures in the central part of the sample. This is explained by the fact that, in this region, the energy is reduced by forming small-scale oscillatory patterns with alternating shears, as discussed at the end of Section 3.1.…”

Section: Finite-element Computationsmentioning

confidence: 99%

Multiscale Modeling of Materials — the Role of Analysis

Conti

DeSimone

Dolzmann

et al. 2003

Trends in Nonlinear Analysis

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We present two case studies how analysis can be used to derive a hierarchy of models to capture multiscale behavior of materials. The determination, via Γ-convergence, of the thin film limit of micromagnetism delivers a reduced two-dimensional model for soft ferromagnetic films which justifies previously known theories for small fields and extends them to the regime of field penetration. The analytic evaluation of the quasiconvex envelope of the microscopic energy density of nematic elastomers allows efficient numerical computations with finite elements and shows the existence of a new "smectic" phase. In both cases, the numerical solution of the coarse-grained model is complemented by a reconstruction of the microscopic pattern associated with the reduced field.

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Monodomain liquid crystalline networks: reorientation mechanism from uniform to stripe domains

Cited by 72 publications

References 26 publications

Numerical study of stretched smectic-Aelastomer sheets

Numerical study of stretched smectic-Aelastomer sheets

Negative Poisson's ratio and semisoft elasticity of smectic-Cliquid-crystal elastomers

Multiscale Modeling of Materials — the Role of Analysis

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