Computational analysis of liquid crystalline elastomer membranes: Changing Gaussian curvature without stretch energy

Cirak, Fehmi; Long, Quan; Bhattacharya, Kaushik; Warner, Mark

doi:10.1016/j.ijsolstr.2013.09.019

Cited by 40 publications

(65 citation statements)

References 24 publications

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“…When η 0 and η 1 are active, assuming that equations (3.8) can be solved explicitly, we can write 13) and then define the energy function on unloading as…”

Section: (B) the Pseudo-anelastic Energy Function For Liquid Crystal mentioning

confidence: 99%

“…In general, these responses are interpreted as being due to changes in the microstructural texture or viscoelasticity, but we do not consider microstructural or time-dependent effects here. In Section 2, we recall the neoclassical modelling strategy where we adopt the isotropic phase at high temperature as the reference configuration [13,[18][19][20][21], rather than the nematic phase in which the crosslinking was produced [4,10,76,80,81,84,90]. Our choice is phenomenologically motivated by the multiplicative decomposition of the deformation gradient from the reference configuration to the current configuration into an elastic distortion followed by a natural (stress free) shape change.…”

Section: Introductionmentioning

confidence: 99%

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A pseudo-anelastic model for stress softening in liquid crystal elastomers

Mihai

Goriely

2020

Proc. R. Soc. A.

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Liquid crystal elastomers exhibit stress softening with residual strain under cyclic loads. Here, we model this phenomenon by generalizing the classical pseudo-elastic formulation of the Mullins effect in rubber. Specifically, we modify the neoclassical strain-energy density of liquid crystal elastomers, depending on the deformation and the nematic director, by incorporating two continuous variables that account for stress softening and the associated set strain. As the material behaviour is governed by different forms of the strain-energy density on loading and unloading, the model is referred to as pseudo-anelastic. We then analyse qualitatively the mechanical responses of the material under cyclic uniaxial tension, which is easier to reproduce in practice, and further specialize the model in order to calibrate its parameters to recent experimental data at different temperatures. The excellent agreement between the numerical and experimental results confirms the suitability of our approach. Since the pseudo-energy function is controlled by the strain-energy density for the primary deformation, it is valid also for materials under multiaxial loads. Our study is relevant to mechanical damping applications and serves as a motivation for further experimental tests.

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“…When η 0 and η 1 are active, assuming that equations (3.8) can be solved explicitly, we can write 13) and then define the energy function on unloading as…”

Section: (B) the Pseudo-anelastic Energy Function For Liquid Crystal mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A pseudo-anelastic model for stress softening in liquid crystal elastomers

Mihai

Goriely

2020

Proc. R. Soc. A.

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“…If they are assumed to be totally excluded, the problem reduces to constructing a surface with a metric determined by intrinsic deformation [3,7,9]. In this approximation, deformation of a nematoelastic shell is similar to that of membranes governed by curvature-elasticity theory [44].…”

Section: Basic Equationsmentioning

confidence: 99%

“…It is, however, not sufficient for visualising the actual shape generated by embedding a surface with a given metric into 3D space, which requires numerical computation [7,9], except in simplest symmetrical settings yielding surfaces of revolution, such as a cone [3] or a (pseudo)spherical segment [4]. The often repeated statement that Gaussian curvature can be created without costs in stretching energy does not apply to the defect cores or boundary layers near interphase boundaries [10].…”

Section: Introductionmentioning

confidence: 99%

Textures and shapes in nematic elastomers under the action of dopant concentration gradients

Zakharov

Pismen

2017

Soft Matter

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We explore a novel strategy of patterning nematic elastomers that does not require inscribing the texture directly. It is based on varying the dopant concentration that, beside shifting the phase transition point, affects the nematic director field via coupling between the gradients of concentration and nematic order parameter. Rotation of the director around a point dopant source causes topological modification manifesting itself in a change of the number of defects. A variety of shapes, dependent on the dopant distribution, are obtained by anisotropic deformation following the nematic-isotropic transition.

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“…Any change in nematic order in a nematic elastomer film causes it to deform. Following the early theoretical prediction of deformation of monodomain liquid crystal elastomers [1], its first experimental realization [2], and the development of theory combining nematic and elastic contributions to the Landau -de Gennes functional [3][4][5][6], a variety of shapes in patterned nematoelastic films have been constructed in recent years [7][8][9][10][11][12]. The various shapes have been produced by imposing a desired orientation in a liquid-crystalline film prior to polymerization and heating the textured nematoelastic film above the NIT point [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Phase separation and folding in swelled nematoelastic films

Zakharov

Pismen

2017

Phys. Rev. E

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We explore reshaping of nematoelastic films upon imbibing an isotropic solvent under conditions when isotropic and nematic phases coexist. The structure of the interphase boundary is computed taking into account the optimal nematic orientation governed by interaction of gradients of the nematic order parameter and solvent concentration. This structure determines the effective line tension of the boundary. We further compute equilibrium shapes of deformed thin sheets and cylindrical and spherical shells with the rectilinear or circular shape of the boundary between nematic and isotropic domains. A differential expansion or contraction near this boundary generates a folding pattern spreading out into the bulk of both phases. The hierarchical ordering of this pattern is most pronounced on a cylindrical shell.

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Computational analysis of liquid crystalline elastomer membranes: Changing Gaussian curvature without stretch energy

Cited by 40 publications

References 24 publications

A pseudo-anelastic model for stress softening in liquid crystal elastomers

A pseudo-anelastic model for stress softening in liquid crystal elastomers

Textures and shapes in nematic elastomers under the action of dopant concentration gradients

Phase separation and folding in swelled nematoelastic films

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