We present an approach to understand geometric-incompatibility-induced rigidity in underconstrained materials, including subisostatic 2D spring networks and 2D and 3D vertex models for dense biological tissues. We show that in all these models a geometric criterion, represented by a minimal length [Formula: see text], determines the onset of prestresses and rigidity. This allows us to predict not only the correct scalings for the elastic material properties, but also the precise magnitudes for bulk modulus and shear modulus discontinuities at the rigidity transition as well as the magnitude of the Poynting effect. We also predict from first principles that the ratio of the excess shear modulus to the shear stress should be inversely proportional to the critical strain with a prefactor of 3. We propose that this factor of 3 is a general hallmark of geometrically induced rigidity in underconstrained materials and could be used to distinguish this effect from nonlinear mechanics of single components in experiments. Finally, our results may lay important foundations for ways to estimate [Formula: see text] from measurements of local geometric structure and thus help develop methods to characterize large-scale mechanical properties from imaging data.
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http://dx.doi.org/10.1073/pnas.1815436116 | DOI Listing |
Phys Rev E
November 2022
Department of Physics and BioInspired Institute, Syracuse University, Syracuse, New York, USA.
We study geometrical clues of a rigidity transition due to the emergence of a system-spanning state of self-stress in underconstrained systems of individual polygons and spring networks constructed from such polygons. When a polygon with harmonic bond edges and an area spring constraint is subject to an expansive strain, we observe that convexity of the polygon is a necessary condition for such a self-stress. We prove that the cyclic configuration of the polygon is a sufficient condition for the self-stress.
View Article and Find Full Text PDFSoft Matter
July 2022
CNRS, Centre de Physique Théorique (CPT, UMR 7332), Turing Center for Living Systems, Aix Marseille Univ, Université de Toulon, Marseille, France.
Disordered spring networks are a useful paradigm to examine macroscopic mechanical properties of amorphous materials. Here, we study the elastic behavior of under-constrained spring networks, networks with more degrees of freedom than springs. While such networks are usually floppy, they can be rigidified by applying external strain.
View Article and Find Full Text PDFPhys Rev E
February 2022
Department of Physics and BioInspired Institute, Syracuse University, Syracuse, New York 13244, USA.
This is the second paper devoted to energetic rigidity, in which we apply our formalism to examples in two dimensions: Underconstrained random regular spring networks, vertex models, and jammed packings of soft particles. Spring networks and vertex models are both highly underconstrained, and first-order constraint counting does not predict their rigidity, but second-order rigidity does. In contrast, spherical jammed packings are overconstrained and thus first-order rigid, meaning that constraint counting is equivalent to energetic rigidity as long as prestresses in the system are sufficiently small.
View Article and Find Full Text PDFSoft Matter
July 2020
Department of Chemical & Biomolecular Engineering, Rice University, Houston, TX 77005, USA. and Center for Theoretical Biological Physics, Rice University, Houston, TX 77030, USA and Departments of Chemistry and Physics & Astronomy, Rice University, Houston, TX 77005, USA.
Fibrous networks such as collagen are common in physiological systems. One important function of these networks is to provide mechanical stability for cells and tissues. At physiological levels of connectivity, such networks would be mechanically unstable with only central-force interactions.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
April 2019
Department of Physics, Syracuse University, Syracuse, NY 13244.
We present an approach to understand geometric-incompatibility-induced rigidity in underconstrained materials, including subisostatic 2D spring networks and 2D and 3D vertex models for dense biological tissues. We show that in all these models a geometric criterion, represented by a minimal length [Formula: see text], determines the onset of prestresses and rigidity. This allows us to predict not only the correct scalings for the elastic material properties, but also the precise magnitudes for bulk modulus and shear modulus discontinuities at the rigidity transition as well as the magnitude of the Poynting effect.
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