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8 pages, 861 KiB

Open AccessProceeding Paper

Predicting the Flexural Modulus of Variable Pitch Angle, Porous Bouligand Structured 3D Printed Polymer

by Praveenkumar S. Patil, Edward D. McCarthy and Parvez Alam

Mater. Proc. 2025, 20(1), 1; https://doi.org/10.3390/materproc2025020001 - 8 Jan 2025

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Our study considered porous Bouligand structured polymer, comprising polymer fibres with porous spaces between them. These are more complicated structures than the non-porous Bouligand, since the addition of porosity into the material creates a secondary variable besides fibre pitch. There is currently no [...] Read more.

Our study considered porous Bouligand structured polymer, comprising polymer fibres with porous spaces between them. These are more complicated structures than the non-porous Bouligand, since the addition of porosity into the material creates a secondary variable besides fibre pitch. There is currently no analytical model available to predict the modulus of such materials. Our paper explores the correlation between porosity, polymer fibre pitch angle, and flexural modulus in porous Bouligand structured polymers. Our structures were digitally manufactured using stereolithography (SLA) additive manufacturing methods, after which they were subjected to three-point bending tests. Our aim was to simply and parametrically develop an analytical model that would capture the influences of both porosity and polymer fibre pitch angle on the flexural modulus of the material. Our model is expressed as

E_{f} = E_{p o r o} (a θ_{f}^{3} + b θ_{f}^{2} + c θ_{f} + d)

, and we derive this by applying non-linear regression to our experimental data. This model predicts the flexural modulus,

E_{f}

, of porous Bouligand structured polymer as a function of both porosity and pitch angle. Here,

E_{p o r o}

is defined as the solid material modulus,

E_{s o l i d}

, multiplied by porosity,

ϕ

and is a linear reduction in the modulus as a function of increasing porosity, while

θ_{f}

signifies the polymer fibre pitch angle. This relationship is relatively accurate within the range of 10° ≤ θ_f ≤ 50°, and for porosity values ranging from

0.277 \leq 0.356

, as supported by our evidence to date. Full article

(This article belongs to the Proceedings of The 1st International Online Conference on Biomimetics)

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10 pages, 1433 KiB

Open AccessProceeding Paper

Biomimetic-Hydrogel-Based Electronic Skin: An Overview Based on Patenting Activities and the Market

by Ahmed Fatimi

Mater. Proc. 2025, 20(1), 2; https://doi.org/10.3390/materproc2025020002 - 28 Feb 2025

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Abstract

Electronic skin (e-skin) is an innovative technology characterized by its flexibility, stretchability, and self-healing properties, designed to biomimic the functionalities of human or animal skin. This technology is well-suited for applications in robotics, prosthetics, and health monitoring since it can sense a wide [...] Read more.

Electronic skin (e-skin) is an innovative technology characterized by its flexibility, stretchability, and self-healing properties, designed to biomimic the functionalities of human or animal skin. This technology is well-suited for applications in robotics, prosthetics, and health monitoring since it can sense a wide range of tactile signals, such as humidity, pressure, temperature, and stress. Developing e-skin for wearable devices faces several challenges. One major challenge is the need for soft and stretchable electronic materials, as conventional materials are brittle. Furthermore, the development of skin-like hydrogel devices for wearable electronics faces challenges such as limited functionality, low ambient stability, poor surface adhesion, and relatively high power consumption. Innovation in this area has the potential to pay off. Organizations that invest in and develop innovative e-skin technologies based on biomimetic hydrogels can secure intellectual property rights through patents. This study is dedicated to reviewing the state of the art by presenting what has been patented concerning biomimetic-hydrogel-based e-skin. At the end, a section presents relevant patents to demonstrate the innovation and formulation of such hydrogels as biomimetic materials for e-skin applications. A market overview of e-skins is also presented. This contextualizes the significance of research in biomimetic-hydrogel-based e-skins within the broader commercial landscape. Full article

(This article belongs to the Proceedings of The 1st International Online Conference on Biomimetics)

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12 pages, 6353 KiB

Open AccessProceeding Paper

Low-Velocity Impact Behaviour of Biomimetic Cornstalk-Inspired Lightweight Structures

by Shakib Hyder Siddique, Paul J. Hazell, Gerald G. Pereira, Hongxu Wang and Juan P. Escobedo

Mater. Proc. 2025, 20(1), 3; https://doi.org/10.3390/materproc2025020003 - 6 Mar 2025

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Abstract

This study investigates the dynamic response and damage characteristics of cornstalk-inspired lightweight structures. Specimens were fabricated via 3D printing using Acrylonitrile Butadiene Styrene (ABS) as the chosen thermoplastic due to its toughness and resistance to impact. Low-velocity impact tests were conducted at varying [...] Read more.

This study investigates the dynamic response and damage characteristics of cornstalk-inspired lightweight structures. Specimens were fabricated via 3D printing using Acrylonitrile Butadiene Styrene (ABS) as the chosen thermoplastic due to its toughness and resistance to impact. Low-velocity impact tests were conducted at varying incident energies, with subsequent damage analyses performed using X-ray CT scans. The effect of geometrical variations in the constituents on energy-absorbing capability was also investigated. The results demonstrate a ~14% increase in specific energy absorption (SEA) compared to quasi-static measurements. This research is built upon the authors’ previous work on the quasi-static response of the cornstalk-inspired design. Full article

(This article belongs to the Proceedings of The 1st International Online Conference on Biomimetics)

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7 pages, 2143 KiB

Open AccessProceeding Paper

Performance of Fish Scale-Inspired Armour Subjected to Impact Loading by Different Impactor Shapes: A Numerical Investigation

by Hari Bahadur Dura, Paul J. Hazell and Hongxu Wang

Mater. Proc. 2025, 20(1), 4; https://doi.org/10.3390/materproc2025020004 - 6 Mar 2025

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Abstract

This paper investigates the impact performance of a hybrid scale–tissue structure inspired by elasmoid fish scales. Acrylonitrile butadiene styrene (ABS) acted as the hard scales, whereas thermoplastic polyurethane (TPU) mimicked the soft tissue. Low-velocity impact scenarios were investigated using a commercially available software, [...] Read more.

This paper investigates the impact performance of a hybrid scale–tissue structure inspired by elasmoid fish scales. Acrylonitrile butadiene styrene (ABS) acted as the hard scales, whereas thermoplastic polyurethane (TPU) mimicked the soft tissue. Low-velocity impact scenarios were investigated using a commercially available software, ANSYS LS-Dyna. The effect of indenter shape (conical, hemispherical, and flat head) was studied at three impact energy levels (50 J, 75 J, and 100 J). The specific energy absorbed for the conical indenter was the highest. The peak force for the conical, hemispherical, and flat-head indenters at an impact energy of 100 J was 6.0 kN, 5.4 kN, and 4.5 kN, respectively. The primary failure modes were shear failure and tensile breaking of the scales. The present study highlights the effect of indenter shape on the impact behaviour of a fish scale-inspired structure. Full article

(This article belongs to the Proceedings of The 1st International Online Conference on Biomimetics)

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8 pages, 7098 KiB

Open AccessProceeding Paper

Caninoid Necro-Robots: Geometrically Selected Rearticulation of Canine Mandibles

by Ben Jørgensen, Oscar Powell, Freddie Coen, Jack Lord, Yang Han Ng, Jeremiah Brennan, Gurå Therese Bergkvist and Parvez Alam

Mater. Proc. 2025, 20(1), 5; https://doi.org/10.3390/materproc2025020005 - 12 Mar 2025

Viewed by 478

Abstract

In line with Sustainable Development Goal 9 (sustainable industrialisation and innovation), environmentally responsible engineering designs in modern robotics should consider factors such as renewability, sustainability, and biodegradability. The robotics sector is growing at an exponential rate and, as a consequence, its contribution to [...] Read more.

In line with Sustainable Development Goal 9 (sustainable industrialisation and innovation), environmentally responsible engineering designs in modern robotics should consider factors such as renewability, sustainability, and biodegradability. The robotics sector is growing at an exponential rate and, as a consequence, its contribution to e-waste is a growing concern. Our work contributes to the technological development of caninoid necro-robots, robots that are built from the skeletons of deceased dogs. The already formed skeletal structures of deceased dogs (and other animals) are ideal natural material replacements for synthetic robotic architectures such as plastics, metals, and composites. Since dog skeletons are disarticulated, simple but effective methods need to be developed to rearticulate their bodies. The canine head is essentially a large end effector, but its mandible is held together by a fibrocartilaginous joint (symphysis) that degrades at a higher rate than the bone itself. The degradation of the symphysis would ordinarily negate the utility of a canine head as a necro-robotic end effector; however, in this research, we consider simple methods of mandible reinforcement to circumvent this problem. Our research uses 3D scans of a real canine head, which is modelled using the finite element method to ascertain optimal geometrical reinforcements for the mandible. The full head structures and their reinforcements are printed and adhesively connected to determine the most effective reinforcing strategy of the mandible. Here, we elucidate geometrically selected reinforcement designs that are evidenced through mechanical testing, to successfully increase the stiffness of a disarticulated mandible. Full article

(This article belongs to the Proceedings of The 1st International Online Conference on Biomimetics)

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7 pages, 655 KiB

Open AccessProceeding Paper

Fish Scale-Inspired Stab-Resistant Body Armour

by Sidharath Sharma and Parvez Alam

Mater. Proc. 2025, 20(1), 6; https://doi.org/10.3390/materproc2025020006 - 12 Mar 2025

Viewed by 291

Abstract

While commercially available lightweight “stab-proof” apparel exists, it offers little resistance to true stabbing as it is primarily designed to withstand slash attacks. Yet, crimes involving the use of a knife or sharp instrument have consistently been rising in the UK over several [...] Read more.

While commercially available lightweight “stab-proof” apparel exists, it offers little resistance to true stabbing as it is primarily designed to withstand slash attacks. Yet, crimes involving the use of a knife or sharp instrument have consistently been rising in the UK over several decades. For the most part, the various proposed solutions to stab-proofing are based on speciality textiles and while these have shown success in slash-proofing, their utility for stab-proofing is still somewhat of a misnomer. Nature showcases a plethora of puncture-resisting materials and structures. At the macro-scale, these include carapaces, egg cases, toughened skin, and more. One of the most effective protective mechanisms known comes through surface scaling, present on animals such as reptiles and fish. Scaled protective armours present in extant fish species include overlapping elasmoid scales, interlocking ganoid scales, placoid scales, tessellating carapace scutes, and interlocking plates. Here, we research overlapping and interlocking scaled structures to ascertain the stab penetration resistance of biomimetic scaled structures against continuum material to obtain the force–time relationship of the impact event as well as ascertaining the penetration depth. We use additive manufacturing methods to manufacture biomimetic armour made of nylon, a common protective artificial material used in slash-proofing textiles. Stab testing to the closely replicated HOSDB body armour standard 2017, we find that biomimetic scales made of nylon offer greater protection against direct stabbing than continuum nylon material sheets. This can be attributed to (a) the heightened flexibility in an interlocked fish scale structure that does not exist in a continuum sheet of the same material; (b) the effect of overlapping of the fish scales, resulting in a greater penetration depth requirement before the structure undergoes perforation; and (c) segmentation into smaller armour plates (of the same thickness) rather than continuum sheets provides a lower span-to-depth ratio, therefore leading to a smaller deflection of the plate upon impact and a greater deceleration and, hence, a greater impact force. Full article

(This article belongs to the Proceedings of The 1st International Online Conference on Biomimetics)

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7 pages, 2393 KiB

Open AccessProceeding Paper

Basic Understanding of the Flow Characteristics over a Bio-Inspired Corrugated Wing at a Low Reynolds Number (10’000) in Gliding Flight

by Almajd Alhinai and Torsten Schenkel

Mater. Proc. 2025, 20(1), 7; https://doi.org/10.3390/materproc2025020007 - 13 Mar 2025

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Abstract

A computational fluid dynamics-based study of a corrugated wing section inspired by the dragonfly wing was performed for a low Reynolds number (10’000), focusing on gliding flight. The aerodynamic characteristics are compared to those of a typical technical aerofoil (NACA 0009). The objective [...] Read more.

A computational fluid dynamics-based study of a corrugated wing section inspired by the dragonfly wing was performed for a low Reynolds number (10’000), focusing on gliding flight. The aerodynamic characteristics are compared to those of a typical technical aerofoil (NACA 0009). The objective of this study is to develop a simulation tool for the design and development of corrugated wings for aerospace applications and to gain a better understanding of the flow over corrugated wing sections. The simulation results were verified using a convergence study and validated by an angle of attack study and comparison with experimental results. The results demonstrated the simulations capability of predicting key flow features but there were some discrepancies from the experimental observations, mainly the prediction of the critical angle of attack. Overall, the simulation results demonstrated a comparable, if not better, aerodynamic performance compared to the technical aerofoil. Full article

(This article belongs to the Proceedings of The 1st International Online Conference on Biomimetics)

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7 pages, 2607 KiB

Open AccessProceeding Paper

Perspective on the Biomimetic Approaches for the Design of Hydrophobic and Antimicrobial Paper Coatings with Hierarchical Surface Structures

by Pieter Samyn

Mater. Proc. 2025, 20(1), 8; https://doi.org/10.3390/materproc2025020008 - 17 Apr 2025

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Abstract

The design of functional paper coatings with excellent barrier properties, including water repellence, anti-microbial properties, and recyclability, is highly demanded in view of the sustainable use of paper as flexible substrates for various industrial applications such as packaging. The enhanced coating functionalities should [...] Read more.

The design of functional paper coatings with excellent barrier properties, including water repellence, anti-microbial properties, and recyclability, is highly demanded in view of the sustainable use of paper as flexible substrates for various industrial applications such as packaging. The enhanced coating functionalities should be incorporated through a combination of selected bio-based materials and the creation of appropriate surface textures enhancing coating performance. The bio-inspired approaches through the replication of hierarchical surface structures with multi-scale dimensional features in combination with selection of appropriate bio-based functional groups offer new concepts for coating design. In this short perspective paper, concepts in the field are illustrated with a focus on the combination of hydrophobic and anti-microbial properties. Based on long-term work with the available toolbox of bio-based building blocks and nanoscale architectures, they can be processed into applicable aqueous suspensions for sprayable paper coatings. The macroscopic roughness profile of paper substrates can be complemented through the decoration of nanoscale bio-based polymer particles of polyhydroxybutyrate or vegetable oil capsules with dimensions in the range of 20–50 nm or 100–500 nm depending on the synthesis conditions. The anti-microbial properties can be provided by the surface modification of nanocellulose with biologically active molecules sourced from nature. Besides the more fundamental issues in design and synthesis, the industrial application of the bio-inspired coatings through spray-coating becomes relevant. Full article

(This article belongs to the Proceedings of The 1st International Online Conference on Biomimetics)

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