Abstract
In this paper, a new kind of hierarchical tube with a negative Poisson’s ratio (NPR) is proposed. The first level tube is constructed by rolling up an auxetic hexagonal honeycomb. Then, the second level tube is produced by substituting the arm of the auxetic sheet with the first level tube and rolling it up. The Nth () level tube can be built recursively. Based on the Euler beam theory, the equivalent elastic parameters of the NPR hierarchical tubes under small deformations are derived. Under longitudinal axial tension, instead of shrinking, all levels of the NPR hierarchical tubes expand in the transverse direction. Using these kinds of auxetic tubes as reinforced fibers in composite materials would result in a higher resistance to fiber pullout. Thus, this paper provides a new strategy for the design of fiber reinforced hierarchical bio-inspired composites with a superior pull-out mechanism, strength and toughness. An application with super carbon nanotubes concludes the paper.
Highlights
IntroductionIn the last few years, due to their special mechanical and electronic properties, hierarchical covalent two-dimensional (2D) and three-dimensional (3D) networks based on one-dimensional (1D)
In the last few years, due to their special mechanical and electronic properties, hierarchical covalent two-dimensional (2D) and three-dimensional (3D) networks based on one-dimensional (1D)nanostructures have attracted much research attention
Different numerical methods have been applied to study the mechanical properties of the super carbon nanotubes (STs), such as continuum mechanics [16,17], molecular dynamics [18,19] and molecular structure mechanics [20,21]
Summary
In the last few years, due to their special mechanical and electronic properties, hierarchical covalent two-dimensional (2D) and three-dimensional (3D) networks based on one-dimensional (1D). Could be introduced if we appropriately modify the geometrical structures of the super tubes Due to their special deformation characteristics, the NPR materials have drawn considerable attentions in the past years. With respect to the NPR fibers, it is easy to imagine that under tension, instead of shrinking, they will expand in a perpendicular direction to the loading direction and could have some interesting properties, when used as fiber-reinforcements in composites These properties include enhanced toughness, shear stiffness and pull-out resistance, and so on [24,43,47,49]. Such auxetic hierarchical fibers are ideal to increase the pull-out resistance and, the toughness of bio-inspired composites
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