Strain-stiffening critical exponents of fiber networks under uniaxial deformation
Universität Augsburg（奥格斯堡大学）；Rice University（莱斯大学）；Institut für Physik, Universität Augsburg（奥格斯堡大学物理研究所）；Department of Chemical and Biomolecular Engineering, Rice University（莱斯大学生物化学工程系）；Center for Theoretical Biological Physics, Rice University（莱斯大学理论生物物理中心）；Department of Chemistry, Rice University（莱斯大学化学系）；Department of Physics and Astronomy, Rice University（莱斯大学物理与天文系）；Bereich Theorie der Polymere, Leibniz-Institut für Polymerforschung（莱布尼茨高分子研究所聚合物理论部）
Atharva Pandit, Fred C. MacKintosh, Abhinav Sharma
Disordered fiber networks exhibit a floppy to rigid mechanical phase transition as a function of connectivity. Sub-isostatically connected networks can undergo this transition via straining. Critical exponents governing this transition have been estimated theoretically and by numerical simulations of various types of networks. In this study, we present improved results, achieved through a combination of refined numerical simulations, larger system sizes and incorporation of theoretical predictions for better post-simulation analysis. We also report the evolution of the critical strain and critical exponents as the network is sheared while being subjected to non-volume-preserving uniaxial deformations.
Packings of macroscopic granular chains capture some of the essential aspects of molecular polymer systems and have been suggested as a paradigm to understand the physics on a molecular scale. However, here we demonstrate that the interparticle friction $μ$ in granular chain packings, which has no counterpart in polymer systems, leads to a nontrivial yielding and rheological response. Based on discrete element simulations we study the nonlinear rheology of random packings of granular chains under large amplitude oscillatory shear. We find that the maximum stress and the penetration depth of th…
Stress induced yielding/fluidization in disordered solids, characterized by irreversibility and enhanced dissipation, is important for a wide range of industrial and geological processes. Although, such phenomena in thermal systems have been extensively studied, they remain poorly understood for granular solids. Here, using oscillatory shear rheology and in-situ optical imaging, we study energy dissipation in a dense granular suspension of adhesive particles that forms yield stress solids far below the isotropic jamming point obtained in the limit of hard-sphere repulsion. We find interesting …
Bistability of cellular traction on strain-stiffening substrates
Universitat de Barcelona（巴塞罗那大学）；Institució Catalana de Recerca i Estudis Avançats (ICREA)（加泰罗尼亚研究与高等学院）；Max Planck Institute for the Physics of Complex Systems（马克斯·普朗克复杂系统物理研究所）；TU Dresden（德累斯顿工业大学）
Emergent Strain-Stiffening in Interlocked Granular Chains
颗粒链填料表现出惊人的紧急应变硬化行为，尽管个别松散的本构链。使用这样的组件上的压痕实验，我们测量的集体阻力$F$的压痕深度$z$的指数增加，并与每链的珠的数量$\mathcal{N}$的平方根。这两个观察结果分别让人想起绞盘或交错书籍中摩擦力的自放大，以及聚合物物理学。基于这两种成分的新模型很好地捕获了实验数据。具体地说，阻力被发现根据通用关系：$\log F \sim μ\sqrt{\mathcal{N}} Φ^{11/8}z/ b $，其中$μ$是两个基本珠之间的摩擦系数，$b$是它们的大小，和$Φ$是链珠的体积分数时，在周围介质中的未连接的珠半稀释。我们的研究表明，通常局限于分子水平的高分子物理领域的理论可以用来解释宏观水平的现象。这类系统可以研究复杂组件中的摩擦，对新材料的设计，纺织工业和生物学具有实际意义。
This paper presents an electromechanical analysis of the nonlinear static response and the superimposed small-amplitude wave characteristics in an infinite periodic compressible dielectric elastomer (DE) laminate subjected to electrostatic excitations and prestress in the thickness direction. The enriched Gent material model is employed to account for the effects of strain stiffening and electrostriction of the DE laminate. The theory of nonlinear electroelasticity and related linearized incremental theory are exploited to derive the governing equations of nonlinear response and the dispersion…
Disordered spring networks are a useful paradigm to examine macroscopic mechanical properties of amorphous materials. Here, we study the elastic behavior of under-constrained spring networks, i.e.\ networks with more degrees of freedom than springs. While such networks are usually floppy, they can be rigidified by applying external strain. Recently, an analytical formalism has been developed to predict the mechanical network properties close to this rigidity transition. Here we numerically show that these predictions apply to many different classes of spring networks, including phantom triangu…
We investigate the cyclic mechanical behavior in uniaxial tension of three different commercial thermoplastic polyurethane elastomers (TPU) often considered as a sustainable replacement for common filled elastomers. All TPU have similar hard segment contents and linear moduli but sensibly different large strain properties as shown by X-Ray analysis. Despite these differences, we found a stiffening effect after conditioning in step cyclic loading which greatly differs from the common softening (also referred as Mullins effect) observed in chemically crosslinked filled rubbers. We propose that t…
Uniaxial-strain Control of Nematic Superconductivity in Sr$_{x}$Bi$_2$Se$_3$
向列相态的特征在于没有平移有序的旋转对称性破缺。近年来，人们发现了超导能隙自发地提升晶格转动对称性的超导现象。然而，配对机制和机制决定的取向仍然没有得到解决。第一步是通过施加外部破缺磁场来证明向列性的控制，以确定耦合到晶格的符号和强度。在这里，我们报告的第一次控制的超导性的Sr $_x$ Bi $_2$ Se $_3$，通过外部施加的单轴应力的取向。亚结构域的抑制表明，它是$Δ_{4y}$状态，是最有利的压缩下沿基础Bi-Bi键。这些结果提供了一个不可避免的一步，了解独特的拓扑超导电性的微观起源。
