Islam M R, Picu R C
Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
Phys Rev E. 2019 Jun;99(6-1):063001. doi: 10.1103/PhysRevE.99.063001.
The mechanical behavior of athermal random fiber networks embedding particulate inclusions is studied in this work. Composites in which the filler size is comparable with the mean segment length of the network are considered. Inclusions are randomly distributed in the network at various volume fractions, and cases in which fibers are rigidly bonded to fillers and in which no such bonding is imposed are studied separately. In the presence of inclusions, the small strain modulus increases, while the ability of the network to strain stiffen decreases relative to the unfilled network case. The reinforcement induced by fillers is most pronounced in sparse networks of floppier filaments that deform in the bending-dominated mode in the unfilled state. As the unfilled network density or the bending stiffness of fibers increases, the effect of filling diminishes rapidly. Fillers lead to a transition from the soft, bending-dominated, to the stiffer, stretching-dominated, deformation mode of the network, a transition which is primarily responsible for the observed overall reinforcement. The confinement, i.e., the restriction on network kinematics imposed by fillers, causes this transition. These results provide a justification for the observed difference in reinforcement obtained in sparsely versus densely cross-linked networks at a given filling fraction and provide guidance for the further development of network-based materials.
本文研究了嵌入颗粒夹杂的非热随机纤维网络的力学行为。考虑了填料尺寸与网络平均段长相当的复合材料。夹杂在网络中以各种体积分数随机分布，分别研究了纤维与填料刚性结合以及不存在这种结合的情况。在存在夹杂的情况下，小应变模量增加，而网络应变硬化的能力相对于未填充网络的情况有所降低。填料引起的增强作用在较软细丝的稀疏网络中最为明显，这些细丝在未填充状态下以弯曲主导模式变形。随着未填充网络密度或纤维弯曲刚度的增加，填充效果迅速减弱。填料导致网络从柔软的、弯曲主导的变形模式转变为更硬的、拉伸主导的变形模式，这种转变是观察到的整体增强的主要原因。限制作用，即填料对网络运动学的限制，导致了这种转变。这些结果为在给定填充分数下稀疏交联网络与密集交联网络中观察到的增强差异提供了依据，并为基于网络的材料的进一步发展提供了指导。
