Emergence of an apparent yield phenomenon in the mechanics of stochastic networks with inter-fiber cohesion
Emergence of an apparent yield phenomenon in the mechanics of stochastic networks with inter-fiber cohesion
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DOI：
10.1039/d3sm01315d
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发表时间：
2023-11-20
期刊：
影响因子：
3.4
通讯作者：
Picu，R. C.
中科院分区：
文献类型：
--
作者：
Amjad，S. N.;Picu，R. C.
在这项工作中，我们调查的贡献，纤维间的凝聚力，以确定随机交联纤维网络的力学行为。纤维是无热的，并且主要在其弯曲和轴向变形模式中储存能量。纤维之间的内聚力由相互作用势定义。这些结构在施加外部载荷之前与纤维间的内聚力处于平衡状态，并在单轴拉伸下对其力学行为进行了探讨。两种类型的配置被认为是：一个国家与高初始自由体积，其中纤维之间的接触是稀缺的，和一个国家与低自由体积和大量的纤维接触。虽然在没有凝聚力的响应是超弹性的，我们观察到，屈服点的现象发展的凝聚力的强度增加，在这两种网络类型考虑，我们称之为“解锁现象”。小应变刚度随着内聚变得更加显著而增加。刚度和解锁应力用网络参数和粘结强度通过两个函数的乘积表示，一个函数仅依赖于网络参数，另一个函数是粘结强度的函数。虽然小应变响应由内聚力控制，但大应变行为在很大程度上由网络控制。因此，改变内聚强度对应变刚化没有影响。这些观测结果为在无热和热网络材料中观察到的解锁提供了物理基础，并有望促进具有新特性的软材料的设计。
In this work we investigate the contribution of inter-fiber cohesion to defining the mechanical behavior of stochastic crosslinked fiber networks. Fibers are athermal and store energy primarily in their bending and axial deformation modes. Cohesion between fibers is defined by an interaction potential. These structures are in equilibrium with the inter-fiber cohesive forces before external load is applied and their mechanical behavior is probed in uniaxial tension. Two types of configurations are considered: a state with high initial free volume in which contacts between fibers are scarce, and a state with low free volume and large number of fiber contacts. While in the absence of cohesion the response is hyperelastic, we observe that a yield point-like phenomenon develops as the strength of cohesion increases in both network types considered; we refer to this as an ‘unlocking phenomenon’. The small strain stiffness increases as cohesion becomes more pronounced. The stiffness and unlocking stress are expressed in terms of network parameters and cohesion strength through a product of two functions, one dependent on network parameters only, and the other is a function of the cohesion strength. While the small strain response is controlled by cohesion, the large strain behavior is shown to be largely controlled by the network. Therefore, varying the strength of cohesion has no effect on strain stiffening. These observations provide a physical basis for the unlocking observed in both athermal and thermal network materials and are expected to facilitate the design of soft materials with novel properties.