Bio-Inspired Laminates of Different Material Systems

Abstract

Helicoidal laminates mimicking the laminar structure of the exoskeleton of crustaceans have been reported to resist higher out-of-plane loads than the common cross-ply and quasi-isotropic fiber-reinforced laminates. Some have reported that smaller inter-ply angle improves strength of helicoidal laminates but others have reported the opposite. A few important material parameters that dictate the failure mechanism of helicoidal laminates have recently been proposed based on proof-of-concept carbon fiber-reinforced laminates, which is not the best material system to benefit from a helicoidal configuration. This study investigates the out-of-plane loading performance of helicoidal laminates with various inter-ply angles, ply thicknesses, and materials. Result shows that the failure mechanism is dictated by the competition between spiraling matrix split and delamination followed by fiber breakage regardless of the laminate material system. Spiraling matrix split resistance decreases as pitch (ratio of inter-ply angle to ply thickness) and matrix toughness decreases. This study provides guidelines for the optimization of helicoidal laminates. Coexistence of spiraling matrix split and fiber damage is often seen on the failed laminate with the highest peak load. The optimal inter-ply angle provides the optimal spiraling matrix split resistance; so, neither spiraling matrix split nor fiber/delamination damage becomes dominant. Since resistance to spiraling matrix split decreases as pitch or matrix toughness decreases, the optimal inter-ply angle will increase for laminates with weaker matrix or thicker plies and vice versa.

Herringbone-Bouligand CFRP structures: A new tailorable damage-tolerant solution for damage containment and reduced delaminations

“…The published literature on Bouligand-inspired CFRP structures counts several successful attempts of enhancing the damage tolerance to through-the-thickness loads of 'conventional' CFRP structures [2][3][4][5][6][7][8][9][10][11][12][13]. Some of the most relevant accomplishments gathered from the literature are summarised in Table A.…”

“…Helicoidal lamination sequences such as Bouligand-inspired architectures (Figure 1a) have been widely investigated in the past years, leading to successful attempts to enhance the damage tolerance to through-the-thickness loads of fibre reinforced composite materials, including glass fibre reinforced composites [1] and, more frequently, Carbon Fibre Reinforced Plastics (CFRPs) [2][3][4][5][6][7][8][9][10][11][12][13]. Motivated by the enhanced damage tolerance under dynamic and quasi-static through-the-thickness loads of tailored CFRP Bouligand solutions with respect to traditional CFRP laminates, there have been recent developments in our knowledge of the mechanics of Bouligand CFRPs [2][3][4][5][6][7][8][9][10][11][12][13]; these, together with recent developments in automated tow placement, have greatly increased the relevance of Bouligand and Bouligand-inspired structures in Engineering practice.…”

Lightweight, Fiber-Damage-Resistant, and Healable Bio-Inspired Glass-Fiber Reinforced Polymer Laminate

“…The delamination in each interface rotates by a small angle from the previous one, and these delaminations are linked by matrix splits and spiral upwards, similar to a pair of spiral staircases. This is the unique damage pattern of helicoidally stacked fiber-reinforced laminates and is referred to as a spiraling matrix split [ 18 , 22 , 25 ]. Liu et al [ 25 ] and Suksangpanya et al [ 34 ] reported that spiraling matrix split is a form of matrix crack that grows between fibers.…”

“…In the helicoidal structure, the orientation of the fibers in one layer is offset at a slight angle with respect to the fibers in the layer below, forming a spiraling helicoidal configuration. Inspired by these findings, several researchers have conducted studies that mimic the helicoidal structure using CFRP laminates [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. The results show that helicoidal layup significantly improves low-speed impact [ 12 , 13 , 14 , 15 , 16 , 17 ] and high-speed impact performance [ 18 ] of CFRP laminates.…”

“…Several studies [ 18 , 20 , 22 , 23 , 24 , 25 , 26 ] reported that the helicoidal structure also reduces fiber damage in CFRP laminates as well as natural-fiber-reinforced polymer laminates. This is achieved by dissipating energy through mainly helicoidal matrix damage, namely, diffused matrix cracks and delaminations.…”