Development and characterization of novel auxetic structures based on re-entrant hexagon design produced from braided composites

Abstract

This paper reports the first attempt of developing macro-scale auxetic structures based on re-entrant hexagon design from braided composite materials for civil engineering applications. Braided composite rods (BCRs) were produced and arranged as longitudinal and horizontal elements to produce three types of auxetic structures: (1) basic re-entrant hexagon structure, (2) basic structure modified by adding straight longitudinal elements and (3): structure-2 modified by changing structural angle. The influence of various material and structural parameters as well as structure type on Poisson's ratio and tensile properties was thoroughly investigated. The auxetic behaviour was found to strongly depend on the structural angle and straight elements, resulting in lower auxeticity with lower angles and in presence of straight elements. Material parameters influenced the auxetic behaviour to a lesser extent and a decrease in auxetic behaviour was noticed with increase in core fibre linear density and using stiffer fibres such as carbon. The reverse effect was observed in case of tensile strength and work of rupture. Among these structures, structure-3 exhibited good auxetic behaviour, balanced tensile properties, and high energy absorption capacity and their auxetic behaviour could be well predicted with the developed analytical model. Therefore, these novel structures present good potential for strengthening of civil structures.

Auxetic interpenetrating composites: A new approach to non-porous materials with a negative or zero Poisson’s ratio

“…Re-entrant foams are the most common auxetic cellular-network materials, examples include 2D re-entrant honeycombs [18,40], 3D re-entrant foams [4], double-arrowhead re-entrant structure [41], star-shaped structure [42]. In this paper, we study the elastic properties of interpenetrating composites which are reinforced by three different types of regular re-entrant fibre-networks.…”

“…It has already been experimentally demonstrated that composite plates reinforced by an auxetic fibre-network exhibits a negative Poisson's ratio in the thickness direction [39]. Composites reinforced by a re-entrant hexagonal honeycomb are also found to exhibit strong in-plane auxetic behaviour [40]. Available publications on composites with auxetic behaviour are very limited and the properties are in general anisotropic.…”

Braided Fabrication of a Fiber Bragg Grating Sensor

“…The hybrid braiding angles introduce geometrical incompatibility into the longitudinal deformation of the structure, which leads to improved longitudinal stiffness without compromising the bending. The constant and varied braid angles on the conical mandrel’s surface determine the strength of the twist, and the mechanical properties can be designed using an auxiliary structure [ 24 ].…”

In-Plane Behavior of Auxetic Non-Woven Fabric Based on Rotating Square Unit Geometry under Tensile Load

“…Such materials have their potentials as technical textiles in the medicine, automobile, marine and aerospace, architecture, civil engineering, and footwear industries, etc., for filtration where the pore opening size can be controlled by tension, vibration damping, shock absorbency, smart bandages, dental floss with in-built drug release, compression hosiery, seat cushion material, fastening devices, reinforcements in advanced composites, padding material for better forefoot pressure relief in high-heeled shoes, as well as apparel textiles (maternity dresses, bra cups, leggings, children’s wear during the period of growth, support garments, etc.) [4,5,6,7,8,9,10,11,12,13,14].…”