3D bio-inspired hierarchical discontinuous CFRP with enhanced ductility

Rizzo, Francesco; Pinto, Fulvio; Meo, Michele

doi:10.1016/j.compstruct.2019.111202

Cited by 16 publications

(3 citation statements)

References 43 publications

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“…20a), while the typical diamond shape damage that characterizes composite materials failure is detected on the bottom surface (Fig. 20c) (Ref 11,32,33). The LD typology is characterized by a more elastic response showing bent fibers and a reduced indentation on the top surface in proximity of the indenter (Fig.…”

Section: Indentation Testmentioning

confidence: 98%

Design, Manufacturing, and Characterization of Hybrid Carbon/Hemp Sandwich Panels

Boccarusso

Pinto

Fazio

et al. 2021

J. of Materi Eng and Perform

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Advanced sandwich composite structures that incorporate foams or honeycombs as core materials, have been extensively investigated and used in various applications. One of the major limitations of the conventional materials used is their weak impact resistance and their end-of-life recyclability and overall sustainability. This paper is focused on the study of the production and mechanical characterization of hybrid sandwich panels using hemp bi-grid cores that were manufactured with an ad hoc continuous manufacturing process. Bi-grid structures were stratified in multiple layers, resulting in cores with different thicknesses and planar density. Sandwich panels made with carbon fibers skins were then subjected to Low Velocity Impact, compression and indentation and the damaged panels were investigated via CT-Scan. Results show that the high tailorability of the failure modes and the very good energy absorption properties of the hybrid material open new exciting perspectives for the development of new sandwich structures that can extend the use of natural fibers into several industrial applications.

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Section: Indentation Testmentioning

confidence: 98%

Design, Manufacturing, and Characterization of Hybrid Carbon/Hemp Sandwich Panels

Boccarusso

Pinto

Fazio

et al. 2021

J. of Materi Eng and Perform

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“…In this context, biological structures, such nacre [ 8 ], the cuticle of a Scarabaeidae beetle [ 9 ] and the dactyl club of the mantis shrimp [ 10 ], constitute a very interesting source of inspiration since they naturally evolved to function as impact-resistant armour and weaponry for protection and hunting. For instance, the nacre structure shows a brick-and-mortar inner configuration in which strain-hardening features are activated during failure [ 11 , 12 ], while the beetle cuticle is organised in a constant pitch helicoidal structure formed by a constant rotation of the layers through the thickness—also known as a “Bouligand” structure [ 13 , 14 , 15 ]. Extensive research has been focused on the investigation of the behaviour of the helicoidal structure under dynamic conditions, showing improved impact resistance as result of the activation of an additional energy dissipation mechanism called crack twisting [ 9 ].…”

Section: Literature Reviewmentioning

confidence: 99%

Bioinspired Helicoidal Composite Structure Featuring Functionally Graded Variable Ply Pitch

et al. 2021

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Composite laminated materials have been largely implemented in advanced applications due to the high tailorability of their mechanical performance and low weight. However, due to their low resistance against out-of-plane loading, they are prone to generate damage as a consequence of an impact event, leading to the loss of mechanical properties and eventually to the catastrophic failure of the entire structure. In order to overcome this issue, the high tailorability can be exploited to replicate complex biological structures that are naturally optimised to withstand extreme impact loading. Bioinspired helicoidal laminates have been already studied in-depth with good results; however, they have been manufactured by applying a constant pitch rotation between each consecutive ply. This is in contrast to that observed in biological structures where the pitch rotation is not constant along the thickness, but gradually increases from the outer shell to the inner core in order to optimise energy absorption and stress distribution. Based on this concept, Functionally Graded Pitch (FGP) laminated composites were designed and manufactured in order to improve the impact resistance relative to a benchmark laminate, exploiting the tough nature of helicoidal structures with variable rotation angles. To the authors’ knowledge, this is one of the first attempts to fully reproduce the helicoidal arrangement found in nature using a mathematically scaled form of the triangular sequence to define the lamination layup. Samples were subject to three-point bending and tested under Low Velocity Impact (LVI) conditions at 15 J and 25 J impact energies and ultrasonic testing was used to evaluate the damaged area. Flexural After Impact (FAI) tests were used to evaluate the post-impact residual energy to confirm the superior impact resistance offered by these bioinspired structures. Vast improvements in impact behaviour were observed in the FGP laminates over the benchmark, with an average reduction of 41% of the damaged area and an increase in post-impact residual energy of 111%. The absorbed energy was similarly reduced (−44%), and greater mechanical strength (+21%) and elastic energy capacity (+78%) were demonstrated in the three-point bending test.

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“…Patterning the surface of materials based on the surface morphology of some organisms in nature is an important strategy for preparing biomimetic materials. At present, most of them are prepared by laser etching or three-dimensional (3D) printing. − However, these methods are expensive on the one hand, and on the other hand, they cannot completely restore the surface morphology of imitation organisms. Here, we take the example of preparing materials for directional transportation and water collection that imitate the surface of leaves and illustrate a simple and maximum method for reducing biological surfaces.…”

Section: Introductionmentioning

confidence: 99%

Artificial Leaf for Switchable Droplet Manipulation

Liang

Li²,

et al. 2021

Langmuir

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Droplet manipulation plays an important role in scientific research, daily life, and practical production such as biological and chemical analysis. Inspired by the structure and function of three typical leaf veins, the bionic texture was replicated by the template method, and the artificial leaf was selectively treated by nanoparticles to obtain a quasithree-dimensional hybrid superhydrophobic−hydrophilic surface. When the droplet touches the surface of the leaf, it will be attracted to the bottom of the main vein from different directions even in horizontal conditions due to the Laplace pressure gradient and energy gradient. The simulation analysis demonstrates that the reason for directional transportation is the energy gradient of the droplets on the different levels of veins, including the thin veins, lateral veins, and main vein. Meanwhile, the experimental result of water collection also showed an outstanding directional transportation effect and excellent water collection efficiency. In addition, when the sample is tilted upside down, the droplet will flow back to the main vein along the lateral vein and then flow down the main vein, showing a good droplet pumping effect. Therefore, the directional and polydirectional transportation of droplets on the same sample is successfully realized, and the conversion between executing single and multiple tasks simultaneously can be realized only by upright and inverted samples. This work provided a new strategy for directional and polydirectional water manipulation, water collection, directional drainage, and microfluidic devices.

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3D bio-inspired hierarchical discontinuous CFRP with enhanced ductility

Cited by 16 publications

References 43 publications

Design, Manufacturing, and Characterization of Hybrid Carbon/Hemp Sandwich Panels

Design, Manufacturing, and Characterization of Hybrid Carbon/Hemp Sandwich Panels

Bioinspired Helicoidal Composite Structure Featuring Functionally Graded Variable Ply Pitch

Artificial Leaf for Switchable Droplet Manipulation

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