Mechanics of three-dimensional, nonbonded random fiber networks

Abstract

The mechanical behavior of an ensemble of athermal fibers forming a nonbonded network subjected to triaxial compression is studied using a numerical model. The response exhibits a power law dependence of stress on the dilatation strain and hysteresis upon loading and unloading. A stable hysteresis loop results after the first loading and unloading cycle. In the early stages of compaction, strain energy is associated primarily with the bending of fibers, while at higher densities, it is stored primarily in the axial deformation mode. It is shown that the exponent of the power law, and the partition of energy in the axial and bending modes depends on the ratio of the bending to axial stiffness of the fibers. Accounting for interfiber friction does not change the functional form of the stress-strain relationship or the exponent. The central feature that distinguishes the mechanics of this system from that of bonded random networks is the relative sliding at contacts and the ensuing fiber rearrangements. We show that suppressing sliding leads to a much stiffer response. The results indicate that the value of the exponent of the stress-strain power law is determined not only by fiber bending and the formation of new contacts, but also by the relative sliding and axial deformation of fibers.

Toughening of fibrous scaffolds by mobile mineral deposits

“…A broad range of models exists for the modulus of an assemblage of non-crosslinked, non-woven fibers [58, 59, 60, 61, 62]. We applied such models to predict the direction-dependent response of a scaffold clamped and stretched at an angle θ 0 to the dominant direction.…”

An Investigation on triaxial compression of flexible fiber packings

“…Rodney et al also simulated a packing made of a self‐entangled single long coiled wire subject to both tension and compression and found that the packing shows unusual, reversible dilatancy behavior with the Poisson' ratio below 0 in tension and above 0.5 in compression. The fiber stiffness was found to have a significant influence on the compression behavior in the previous simulations . The exponent of the power law, n , depended on the ratio of the bending to axial stiffness of the fibers .…”

“…The fiber stiffness was found to have a significant influence on the compression behavior in the previous simulations . The exponent of the power law, n , depended on the ratio of the bending to axial stiffness of the fibers . When the base fiber network has a very small ratio of the bending to axial stiffness of the fibers, the addition of a small fraction of stiffer fibers dramatically increased the stiffness of the composite by orders of magnitude .…”

“…Numerical simulation studies were also performed on the compression of fibrous materials . From the simulations, the power law relation of pressure and solid volume fraction (i.e., Equation ) was also obtained.…”

Structure-properties relation for random networks of fibers with noncircular cross section

“…In most studies to date all fibers in the network are considered of the same type [5,6,7,8,9] (networks made from dissimilar fibers are studied in [10]) and are, in general, of circular crosssection. However, many athermal fibers have non-circular sections which are characterized by two principal moments of inertia, !…”