Generic elasticity of thermal, under-constrained systems

Fuente: arXiv
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Auteurs principaux: Lee, Cheng-Tai, Merkel, Matthias
Format: Preprint
Publié: 2023
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author Lee, Cheng-Tai
Merkel, Matthias
author_facet Lee, Cheng-Tai
Merkel, Matthias
contents Athermal (i.e. zero-temperature) under-constrained systems are typically floppy, but they can be rigidified by the application of external strain, which is theoretically well understood. Here and in the companion paper, we extend this theory to finite temperatures for a very broad class of under-constrained systems. In the vicinity of the athermal transition point, we derive from first principles expressions for elastic properties such as isotropic tension $t$ and shear modulus $G$ on temperature $T$, isotropic strain $\varepsilon$, and shear strain $γ$, which we confirm numerically. These expressions contain only three parameters, entropic rigidity $κ_S$, energetic rigidity $κ_E$, and a parameter $b_\varepsilon$ describing the interaction between isotropic and shear strain, which can be determined from the microstructure of the system. Our results imply that in under-constrained systems, entropic and energetic rigidity interact like two springs in series. This also allows for a simple explanation of the previously numerically observed scaling relation $t\sim G\sim T^{1/2}$ at $\varepsilon=γ=0$. Our work unifies the physics of systems as diverse as polymer fibers & networks, membranes, and vertex models for biological tissues.
format Preprint
id arxiv_https___arxiv_org_abs_2304_07266
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Generic elasticity of thermal, under-constrained systems
Lee, Cheng-Tai
Merkel, Matthias
Soft Condensed Matter
Statistical Mechanics
Biological Physics
Athermal (i.e. zero-temperature) under-constrained systems are typically floppy, but they can be rigidified by the application of external strain, which is theoretically well understood. Here and in the companion paper, we extend this theory to finite temperatures for a very broad class of under-constrained systems. In the vicinity of the athermal transition point, we derive from first principles expressions for elastic properties such as isotropic tension $t$ and shear modulus $G$ on temperature $T$, isotropic strain $\varepsilon$, and shear strain $γ$, which we confirm numerically. These expressions contain only three parameters, entropic rigidity $κ_S$, energetic rigidity $κ_E$, and a parameter $b_\varepsilon$ describing the interaction between isotropic and shear strain, which can be determined from the microstructure of the system. Our results imply that in under-constrained systems, entropic and energetic rigidity interact like two springs in series. This also allows for a simple explanation of the previously numerically observed scaling relation $t\sim G\sim T^{1/2}$ at $\varepsilon=γ=0$. Our work unifies the physics of systems as diverse as polymer fibers & networks, membranes, and vertex models for biological tissues.
title Generic elasticity of thermal, under-constrained systems
topic Soft Condensed Matter
Statistical Mechanics
Biological Physics
url https://arxiv.org/abs/2304.07266