Measurement of Nonlinear Mechanical Properties of Surfactant-Added Poly(dimethylsiloxane)

Although meta-generalized-gradient approximations (meta-GGAs) are believed potentially the most accurate among the efficient first-principles calculations, the performance has not been accessed on the nonlinear mechanical properties of two-dimensional nanomaterials. Graphene, like two-dimensional silicon carbide g-SiC, has a wide direct band-gap with applications in high-power electronics and solar energy. Taken g-SiC as a paradigm, we have investigated the performance of meta-GGA functionals on the nonlinear mechanical properties under large strains, both compressive and tensile, along three deformation modes using Strongly Constrained and Appropriately Normed Semilocal Density Functional (SCAN) as an example. A close comparison suggests that the nonlinear mechanics predicted from SCAN are very similar to that of Perdew-Burke-Ernzerhof (PBE) formulated functional, a standard Density Functional Theory (DFT) functional. The improvement from SCAN calculation over PBE calculation is minor, despite the considerable increase of computing demand. This study could be helpful in selection of density functionals in simulations and modeling of mechanics of materials.

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A Higher-order Three-scale Reduced Homogenization Approach for Nonlinear Mechanical Properties of 3D Braided Composites

International Journal of Mechanical Sciences ◽

10.1016/j.ijmecsci.2021.106684 ◽

2021 ◽

pp. 106684

Author(s):

Zhiqiang Yang ◽

Yi Sun ◽

Shanqiao Huang ◽

Zihao Yang

Keyword(s):

Mechanical Properties ◽

Higher Order ◽

Braided Composites ◽

3D Braided Composites ◽

Nonlinear Mechanical ◽

Homogenization Approach

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Internal constraints and arrested relaxation in main-chain nematic elastomers

Nature Communications ◽

10.1038/s41467-021-21036-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Takuya Ohzono ◽

Kaoru Katoh ◽

Hiroyuki Minamikawa ◽

Mohand O. Saed ◽

Eugene M. Terentjev

Keyword(s):

Mechanical Properties ◽

Main Chain ◽

Polymer Networks ◽

Nematic Order ◽

Nematic Elastomers ◽

Nematic Director ◽

Highly Nonlinear ◽

Nonlinear Mechanical ◽

Liquid Crystal Elastomers ◽

Memory Applications

AbstractNematic liquid crystal elastomers (N-LCE) exhibit intriguing mechanical properties, such as reversible actuation and soft elasticity, which manifests as a wide plateau of low nearly-constant stress upon stretching. N-LCE also have a characteristically slow stress relaxation, which sometimes prevents their shape recovery. To understand how the inherent nematic order retards and arrests the equilibration, here we examine hysteretic stress-strain characteristics in a series of specifically designed main-chain N-LCE, investigating both macroscopic mechanical properties and the microscopic nematic director distribution under applied strains. The hysteretic features are attributed to the dynamics of thermodynamically unfavoured hairpins, the sharp folds on anisotropic polymer strands, the creation and transition of which are restricted by the nematic order. These findings provide a new avenue for tuning the hysteretic nature of N-LCE at both macro- and microscopic levels via different designs of polymer networks, toward materials with highly nonlinear mechanical properties and shape-memory applications.

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A Molecular Dynamics Study of the Mechanical Properties of Twisted Bilayer Graphene

Micromachines ◽

10.3390/mi9090440 ◽

2018 ◽

Vol 9 (9) ◽

pp. 440 ◽

Cited By ~ 4

Author(s):

Aaron Liu ◽

Qing Peng

Keyword(s):

Mechanical Properties ◽

Molecular Dynamics ◽

Mechanical Strain ◽

Bilayer Graphene ◽

Pristine Graphene ◽

Linear Elastic ◽

Nonlinear Mechanical ◽

Twisted Bilayer Graphene ◽

Dynamics Simulations ◽

Peak Pattern

Graphene is one of the most important nanomaterials. The twisted bilayer graphene shows superior electronic properties compared to graphene. Here, we demonstrate via molecular dynamics simulations that twisted bilayer graphene possesses outstanding mechanical properties. We find that the mechanical strain rate and the presence of cracks have negligible effects on the linear elastic properties, but not the nonlinear mechanical properties, including fracture toughness. The “two-peak” pattern in the stress-strain curves of the bilayer composites of defective and pristine graphene indicates a sequential failure of the two layers. Our study provides a safe-guide for the design and applications of multilayer grapheme-based nanoelectronic devices.

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The Ocular Motor Periphery

The Neurology of Eye Movements ◽

10.1093/med/9780199969289.003.0002 ◽

2015 ◽

pp. 24-54

Author(s):

R. John Leigh ◽

David S. Zee

Keyword(s):

Mechanical Properties ◽

Eye Movements ◽

Neuromuscular Disorders ◽

Cranial Nerves ◽

Fiber Types ◽

Electrophysiological Properties ◽

Nonlinear Mechanical ◽

Clinical Disorders ◽

New Models ◽

Extraocular Proprioception

This chapter reviews contributions of orbital tissues and extraocular muscles (EOM) to the control of eye movements. The anatomy of the orbit, fascia, fibromuscular pulleys, and EOM are described and related to the kinematics of 3-D eye rotations. Current concepts of the embryology of the EOM and their unique and diverse characteristics are described, suggesting why they are more vulnerable to certain neuromuscular disorders and less susceptible to others, compared with skeletal muscles. Electrophysiological properties of different EOM fiber types (and their motor neuron innervation) are contrasted, describing new models that attempt to account for nonlinear mechanical properties of the orbit. The substrate and roles of extraocular proprioception in the control of eye movements are summarized and related to clinical disorders affecting EOM. The anatomy of the cranial nerves supplying the EOM is summarized, diagrammed and highlighted to aid diagnosis of common palsies of the oculomotor, trochlear, and abducens nerves.

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