Nautilus Shell Research Articles

Comparative study on bending behavior and damage analysis of 3D-printed sandwich core designs with bio-inspired reinforcements

In this study, novel sandwich core designs with bio-inspired reinforcements were proposed and their bending behaviors were comparatively examined. The geometrical shapes of alligator osteoderm and chambered nautilus shell were utilized as bio-inspired reinforcements for sandwich core structures. Sandwich core structures were produced through the additive manufacturing method. Experimental tests and finite element analysis were performed to determine the bending performances of the proposed sandwich core structures. The load-carrying capacity, deformation ability, damage-tolerant capability, energy absorption, and damage mechanisms of the proposed sandwich core structures were comparatively investigated through experimental and numerical methods. The orthotropic material model and Hashin’s damage criterion were used in the numerical model of 3D-printed sandwich core structures to consider the effect of the filament raster orientation on the elastic and damage behavior of the sandwich core structures. Compared to the classical honeycomb sandwich core structure, while bio-inspired reinforcements improved the load-carrying capacity and damage-tolerant capability of sandwich core structures, they reduced the energy absorption ability of sandwich core structures due to reducing the vertical deformation ability of sandwich core structures. Bio-inspired reinforcements significantly affected the stress distribution and damage behavior of the sandwich core structures. They reduced von Mises stress level at the outer cell edges of the sandwich core structures and caused reinforcement damage instead of outer cell damage.

Energy absorption characteristics of novel bionic H-type whip restraints for nuclear power plants

To enhance the efficiency of energy absorption in H-type whip restraints for nuclear power plants, this study takes inspiration from the asymmetric twisted lines observed in the Nautilus shell, introducing the Nautilus Bionic Hierarchical Multi-Cell (NBHMC) structure. For different high-energy pipeline sizes and energy absorption quantities, the proposed structures are miniaturized and can be combined into H-type whip restraint by multiple tubes to meet the requirements. The NBHMC structures are investigated based on the validated finite element method, the results demonstrate that the energy absorption per unit mass of the new structure can reach up to 180% of that of the hollow tube, with the maximum enhancement in energy absorption efficiency being 47%. Through parameter analysis of the cross-sectional wall thickness, the highest energy absorption efficiency obtained is 99.62%, with a specific energy absorption of 31.29J/g. Furthermore, utilizing the TOPSIS method, all proposed parameter combinations are ranked, leading to the determination of the optimal parameter combination. Additionally, a theoretical model predicting the mean crushing force is introduced, exhibiting good agreement with numerical simulations. The results presented in this work provide innovative insights for the design of efficient pipe whip restraints.

Electric Field-Driven Jetting and Water-Assisted Transfer Printing for High-Resolution Electronics on Complex Curved Surfaces

High-resolution electronics on complex curved surfaces have wide applications in fields such as biometric health monitoring, intelligent aircraft skins, conformal displays, and biomimetics. However, current manufacturing processes can only adapt to limited curvature, posing a significant challenge for achieving high-resolution fabrication of electronics on complex curved surfaces. In this study, we propose a novel fabrication strategy that combines electric field-driven jetting and water-assisted transfer printing techniques to achieve the fabrication of high-resolution electronics on complex curved surfaces. The electric field-driven jetting enables the fabrication of high-resolution 2D electronics on sacrificial layer substrates. After dissolving the sacrificial layer, it is observed that the 2D electronics form a self-supporting structure with a certain rigidity and flexibility. During the water-assisted transfer printing process, this self-supporting structure undergoes stretching deformation with excellent conformity of the electronics to curved surfaces while effectively minimizing wrinkles. Finally, we successfully demonstrate the manufacture of 25 μm high-resolution electronics on highly curved surfaces (nautilus shell) and complex (scallop shell, stone) surfaces. The integrity of transferred circuit patterns and consistency of conductors are verified through infrared thermography analysis, confirming the feasibility of this manufacturing strategy. In addition, a protective film with strong adhesive properties is sprayed onto the transferred curved circuits to enhance their adhesion and resistance to extreme environments such as acids and alkalis. Our proposed technique provides a simple and effective new strategy for the fabrication of high-resolution electronics on complex curved surfaces.

Organic Challenge: The Organic Challenge: Cultivating Conscious Design for Biodigital Tectonics within AI’s Prompt-to-Pixel Process

The fusion of digital advancements and biological systems is transforming modern-day architecture, and this bio-digital approach, when paired with AI image generation models, promises novel design possibilities. The major drawback of this merger is the dismal performance of AI text-to-image models in translating organic tectonic details into architecture. This study examines the complexity of processes, materials, and techniques necessary in a bio-digital architectural approach. Through a series of digital trials, it identifies the need for sophisticated computational models that can capture the complex intricacies and subtle nuances present in living organisms. Before the testing, a set of parameters considered the limitation of how much tectonic information an image could portray. The Nautilus Shell, ferns, mushrooms, seahorses, and grasshoppers were taken as inspiration models because of varying biological configurations. Next, two AI image-generating tools, Midjourney and Stable Diffusion, were used with three different prompt types, each with varying degrees of complexity drawn from five organic systems. A critical analysis of AI-generated images led to the conclusion that, despite AI's exceptional abilities in creating visual content, the complex comprehension of biological systems and their conversion into architectural designs faced significant challenges.

Design and optimization of bionic Nautilus volute for a hydrodynamic retarder

To reduce the energy loss of volute and improve the emergency braking performance of hydrodynamic retarder under design condition, a bionic volute optimization design method is proposed based on the Nautilus shell. First, the accuracy of the numerical method is verified by grid convergence analysis and experiments. Thereafter, the bionic parametric expression is performed based on the cross-section shape of the Nautilus shell. Subsequently, sample points are created using the Optimal Latin Hypercube sampling method and numerically simulated. Radial basis function neural network and multi-objective genetic algorithm are used for optimization. Finally, the flow field inside the volute and the braking performance of the hydrodynamic retarder are compared by numerical calculation and experiment. Results show that the internal flow field of the bionic volute is more uniform, the energy loss is reduced by 78.95%, and the oil flow speed is increased by 40.61%. In addition, the stable flow field can be established faster during braking, the peak torque can be increased by 6.15%, and the onset time can be advanced by 6.58%. The analysis of energy characteristics shows that the improved performance of the bionic volute can be attributed to its improved internal oil flow conditions, thus reducing the energy loss.

Optimization Layout and Aerodynamic Performance Research on Double Nautilus Vertical-Axis Wind Turbine

The double vertical-axis wind turbine (VAWT) system serves as a high-performance design solution. The Nautilus wind turbine investigated in this research imitated the structure of a Nautilus shell and is a vertical-axis drag-type wind turbine that exhibits relatively low efficiency. Therefore, the improvement of its wind energy efficiency is of paramount importance. This paper utilizes Computational Fluid Dynamics (CFD) software, based on the Reynolds-averaged Navier–Stokes equations and dynamic meshing techniques, to conduct numerical investigations on the aerodynamic performance of the Nautilus wind turbine array layout. The effects of wind direction, spacing ratio, and rotation direction are individually studied, and the interpretations and explanations are provided based on flow field characteristics. The results show that when the wind direction is 90°, i.e., a transverse layout, the closer the spacing between the transverse turbines, the higher the average power coefficient of the entire wind turbine system, with little effect from the three rotation directions. The maximum average power coefficient reached 28.9% and the power gain factor (TPGF) reached 11.1%. The enhancement effect primarily originates from the wake interaction among neighboring turbines. The experimental results showed a deviation of 8.1% compared to the CFD simulation results, thus validating the accuracy of the numerical CFD modeling. Ultimately, several array layouts are proposed, based on the prevalent wind direction and spacing ratio research. The enhancement of the wind turbine array’s situation could significantly increase the average efficiency of the entire wind turbine cluster. Consequently, this study provides a reference for the practical application of biomimetic vertical-axis drag-type wind turbine systems in actual engineering.

Sequins from the sea: Nautilus shell bead technology at Makpan, Alor Island, Indonesia

One defining characteristic of Homo sapiens is the production and use of personal ornamentation. Evidence from Africa and western Eurasia has dominated discussion, but a growing number of finds directs attention towards Island Southeast Asia. In this article, the authors report on an assemblage of Nautilus shell beads from the Indonesian cave site of Makpan, Alor Island. The highly standardised forms, mostly with two perforations, and evidence of use wear, indicate that these beads were utilised as appliqués. Dating to the terminal Pleistocene, these beads appear to form part of a wider tradition also attested on Timor and Kisar, suggesting an early inter-island network across southern Wallacea.

PLA-based nature-inspired architecture for bone scaffolds: A finite element analysis

The implantation of bio-degradable scaffolds is considered as a promising approach to address the repair of bone defects. This article aims to develop a computational approach to study the mechanical behaviour, fluid dynamic, and degradation impact on polylactic acid scaffolds with nature-inspired design structures. Scaffold design is considered to be one of the main factors for the regulation of mechanical characteristics and fluid flow dynamics. In this article, five scaffolds with different nature-inspired architectures have been designed within a specific porosity range. Based on finite element analysis, their mechanical behaviour and computational fluid dynamic study are performed to evaluate the respective properties of different scaffolds. In addition, diffusion-governed degradation analysis of the scaffolds has been performed to compute the total time required for the scaffold to degrade within a given environment. Based on the mechanical behaviour, the Spider-web architecture scaffold was found to have the least deformation, and also the lowest value of equivalent stress and strain. The Nautilus Shell architecture scaffold had the highest value of equivalent stress and strain. The permeability of all the scaffolds was found to meet the requirement of the cancellous bone. All computational fluid dynamics (CFD) results of wall shear stress are in line with the requirement for cell differentiation. It was observed that the Spider-web architecture scaffold had undergone the slowest degradation, and the Giant Water Lily architecture scaffold experienced the fastest degradation.

Shape Memory Effect of Four-Dimensional Printed Polylactic Acid-Based Scaffold with Nature-Inspired Structure.

The four-dimensional (4D) printing is an evolving technology that has immense scope in various fields of science and technology owing to ever-challenging needs of human. It is an innovative upgradation of 3D printing procedure, which instills smart capabilities into materials such that they respond to external stimulus. This article aims to investigate the feasibility of 4D printing of polylactic acid (PLA)-based composite scaffolds fabricated by incorporating four different nature-inspired architectures (honeycomb, giant water lily, spiderweb, and nautilus shell). The composites were developed by adding 1, 3, and 5 wt.% of Calcium Phosphate (CaP) into PLA. Various thermomechanical tests were accomplished to evaluate the properties of developed material. Furthermore, the shape memory characteristics of these scaffolds were examined using thermally controlled conditions. The characterization tests displayed favorable outcomes in terms of thermal stability and hydrophilic nature of the PLA and PLA/CaP composite materials. It was found that the honeycomb structure showed the best shape memory and mechanical behavior among the four designs. Furthermore, the introduction of CaP was found to enhance mechanical strength and shape memory property, whereas the surface integrity was adversely affected. This study can play a vital role in developing self-fitting high-shape recovery biomedical scaffolds for bone-repair applications.

Experimental and numerical investigation of 3D printed bio-inspired lattice structures for mechanical behaviour under Quasi static loading conditions

This research focuses on investigating the design and mechanical aspects of unique bio-inspired structures inspired by the biological elements basal body and nautilus shell. Centriole, nautilus, and cartwheel structures have been designed by CAD software and stereolithography (SLA) 3d printing was applied to manufacture these lattice structures. Finite element analysis was applied to optimize and compressive tests were carried out for the evaluation of the mechanical properties of bioinspired structures. Bio-inspired designs have a combination of qualities, which may create unique mechanical, electrical, thermal, and acoustic characteristics by controlling various factors, which have attracted a lot of study interest. The results of experiments show that the cartwheel structure is stiffer and stronger than other lattices with almost the same volume. According to the mass-to-strength ratio, both cartwheel structures are attractively lightweight and strong. Furthermore, this is the sole study that discusses centriole, nautilus, and cartwheel structure design, manufacturing, and deformation.

Isotope systematics of subfossil, historical, and modern Nautilus macromphalus from New Caledonia.

Cephalopod carbonate geochemistry underpins studies ranging from Phanerozoic, global-scale change to outcrop-scale paleoecological reconstructions. Interpreting these data hinges on assumed similarity to model organisms, such as Nautilus, and generalization from other molluscan biomineralization processes. Aquarium rearing and capture of wild Nautilus suggest shell carbonate precipitates quickly (35 μm/day) in oxygen isotope equilibrium with seawater. Other components of Nautilus shell chemistry are less well-studied but have potential to serve as proxies for paleobiology and paleoceanography. To calibrate the geochemical response of cephalopod δ15Norg, δ13Corg, δ13Ccarb, δ18Ocarb, and δ44/40Cacarb to modern anthropogenic environmental change, we analyzed modern, historical, and subfossil Nautilus macromphalus from New Caledonia. Samples span initial human habitation, colonialization, and industrial pCO2 increase. This sampling strategy is advantageous because it avoids the shock response that can affect geochemical change in aquarium experiments. Given the range of living depths and more complex ecology of Nautilus, however, some anthropogenic signals, such as ocean acidification, may not have propagated to their living depths. Our data suggest some environmental changes are more easily preserved than others given variability in cephalopod average living depth. Calculation of the percent respired carbon incorporated into the shell using δ13Corg, δ13Ccarb, and Suess-effect corrected δ13CDIC suggests an increase in the last 130 years that may have been caused by increasing carbon dioxide concentration or decreasing oxygen concentration at the depths these individuals inhabited. This pattern is consistent with increasing atmospheric CO2 and/or eutrophication offshore of New Caledonia. We find that δ44/40Ca remains stable across the last 130 years. The subfossil shell from a cenote may exhibit early δ44/40Ca diagenesis. Questions remain about the proportion of dietary vs ambient seawater calcium incorporation into the Nautilus shell. Values of δ15N do not indicate trophic level change in the last 130 years, and the subfossil shell may show diagenetic alteration of δ15N toward lower values. Future work using historical collections of Sepia and Spirula may provide additional calibration of fossil cephalopod geochemistry.

Alternative Method of Nature Inspired Geometrical Design Strategy for Drag Induced Wind Turbine Blade Morphology

Although drag driven wind turbine is regarded as an efficient rotor for low wind speed region, design reconfiguration is a continuous process in order to improve the performance of the rotor. The main governing factor that influences the performance of the rotor is the blade morphology. Hence, this paper presents a proposed nature inspired design approach for the development of drag driven wind turbine blade morphology. The design approach framework comprise of 3 main elements namely image processing, geometrical analysis and bio-hybridization. The proposed bio-hybridized design consist of blade mainframe curve inspired by nautilus shell and barnacle on the blade surface. It is found that integration of barnacle geometries on the surface of the blade has affected the performance of the rotor. Result shows that the peak Cm is at λ = 0.55 for experimental and CFD is Cm = 0.238 and Cm = 0.253 respectively. The proposed design resulted in experimental and numerical Cp = 0.113 and Cp = 0.127 respectively at 7 m/s and λ = 0.7. The presented design technique with appropriate design bio-element provides a systematic method for engineers to model wind turbine blade morphologies.

Design of Energy Efficient WSN Using a Noble SMOWA Algorithm

In this paper, the establishment of efficient Wireless Sensor Network (WSN) networks has been projected to minimize the consumption of energy using a new Self-adaptive Multi-Objective Weighted Approach (SMOWA) algorithm for solving a multi-objective problem. The Different WSN nodes deployment policies have been proposed and applied in this paper to design an efficient Wireless Sensor Network to minimize energy consumption. After that, the cluster head for each cluster has been selected with the help of the duty cycle. After configuring the WSN networks, the SMOWA algorithms have been developed to obtain the minimum energy consumption for the networks. Energy minimization, as well as the amount of day-saving, has been calculated for the different WSNs which has been configured through different deployment policies. The major finding of the research paper is to improve the durability of Wireless Sensor Network (i) applying different deployment strategies: (Random, S pattern and nautilus shell pattern), and (ii) using a new Meta-heuristic algorithm (SMOWA Algorithm). In this research, the lifetime of WSN has been increased to a significant level. To choose the best result set from all the obtained results set some constraints such as “equivalent distribution”, “number of repetitions”, “maximum amount energy storage by a node” has been set to an allowable range.

Mathematical Modeling of the Origami Navel Shell

The well-known Nautilus shell has been modeled extensively both by mathematicians and origamists. However, there is wide disagreement on the best-fitting mathematical model — partly because there is significant variability across different Nautilus Shells found in nature, and no single model can describe all of them well. Origami structures, however, have precise repeatable folding instructions, and do not exhibit such variability. Ironically, no known mathematical models exist for these structures. In this research, we mathematically model a prominent origami design, the Navel Shell by Tomoko Fuse, believed to be based on the Nautilus.
 We use first-principles geometric and trigonometric constructs for developing a non-smooth Geometric Model of the ideal origami spiral. We then search for the best-fitting parametric smooth spiral approximation, by formulating the fitting problem as a minimization problem over four unknowns. We write a Python computer program for searching the space numerically. Our evaluations show that: (i) the Smooth spiral is an excellent fit for the Geometric Model; (ii) our models for Origami Navel Shell are different from prior mathematical models for the Nautilus shell, but they come close to a recent model for a rare species of Nautilus; (iii) the Geometric Model explains the outer edges of origami images quite well and helps identify construction errors in the inner edges; and (iv) the Smooth Model helps understand how well the ideal Navel Shell matches different variants of the Nautilus species. We hope our research lays the foundation for further mathematical modeling of origami structures.

An Ingenious Microstructure Arrangement in Deep-Sea Nautilus Shell against the Harsh Environment.

Mollusk shells generally consist of several macro-layers with different microstructures. To explore the specific role that different macro-layers play in the overall mechanical properties of shells, the microstructures, hardness distribution, and three-point bending behavior in the deep-sea Nautilus shell were investigated. It is found that the shell presents a hierarchical structure comprising three layers in thickness, that is, the outer, middle, and inner layers, which exhibit homogeneous, prismatic, and nacreous structures, respectively. Among them, the homogeneous structure in the outer layer is harder, which is beneficial for the shell to enhance resistance to wear and perforation. Furthermore, both the bending strength and fracture energy for group Up (loading from outer to inner surfaces) are far higher than those for group Down (loading from inner to outer surfaces), indicating that the inner nacreous layer is not only stronger but also tougher. Cracks tend to deflect at the interfaces in nacreous structure, and nacreous structure is thereby more resistant to breakage. Hence, the nacreous structure in the inner layer could protect the shell from breaking catastrophically in the deep sea with high pressure. In brief, the combination of a harder outside layer and a tougher inside layer provides an effective protective structure for the deep-sea shell, and the excellent environment adaptability of Nautilus shell can thus be interpreted in terms of its ingenious microstructure arrangement.

Nautilus pompilius

Nautilus pompilius, a ‘living fossil’, has many ancestral features, such as an external chambered shell and pinhole eye, despite its long evolutionary history, thus providing an excellent prototypical model for studying cephalopod evolution. It also has a compact, minimalist genome with fewer genes and slower evolutionary rates in both noncoding and coding regions compared with its sister coleoid genomes. The genome retained a conserved molluscan biomineralization toolkit; relevant proteins such as shell matrix proteins, Sushi/SCR/CCP, laminin, and chitin-binding domains show high similarity with proteins in other mollusks and have massive lineage-specific expanded repetitive low-complexity domains, which co-contribute to the production of aragonite crystals, a major component of the nautilus shell.

The genome of Nautilus pompilius illuminates eye evolution and biomineralization

Nautilus is the sole surviving externally shelled cephalopod from the Palaeozoic. It is unique within cephalopod genealogy and critical to understanding the evolutionary novelties of cephalopods. Here, we present a complete Nautilus pompilius genome as a fundamental genomic reference on cephalopod innovations, such as the pinhole eye and biomineralization. Nautilus shows a compact, minimalist genome with few encoding genes and slow evolutionary rates in both non-coding and coding regions among known cephalopods. Importantly, multiple genomic innovations including gene losses, independent contraction and expansion of specific gene families and their associated regulatory networks likely moulded the evolution of the nautilus pinhole eye. The conserved molluscan biomineralization toolkit and lineage-specific repetitive low-complexity domains are essential to the construction of the nautilus shell. The nautilus genome constitutes a valuable resource for reconstructing the evolutionary scenarios and genomic innovations that shape the extant cephalopods.

The development of nature-inspired gripping system of a flat CFRP strip for stress-ribbon structural layout

Abstract The elegant stress-ribbon systems are efficient in pedestrian bridges and long-span roofs. Numerous studies defined corrosion of the steel ribbons as the main drawback of these structures. Unidirectional carbon fiber-reinforced polymer (CFRP) is a promising alternative to steel because of lightweight, high strength, and excellent corrosion and fatigue resistance. However, the application of CFRP materials faced severe problems due to the construction of the anchorage joints, which must resist tremendous axial forces acting in the stress-ribbons. Conventional techniques, suitable for the typical design of the strips made from anisotropic material such as steel, are not useful for СFRP strips. The anisotropy of СFRP makes it vulnerable to loading in a direction perpendicular to the fibers, shear failure of the matrix, and local stress concentrations. This manuscript proposes a new design methodology of the gripping system suitable for the anchorage of flat strips made from fiber-reinforced polymers. The natural shape of a logarithmic spiral Nautilus shell describes the geometry of the contact surface. The continuous smoothly increasing bond stresses due to friction between the anchorage block and the CFRP strip surface enable the gripping system to avoid stress concentrations. The 3D-printed polymeric prototype mechanical tests proved the proposed frictional anchorage system efficiency and validated the developed analytical model.

A high-strength and high-toughness nacreous structure in a deep-sea Nautilus shell: Critical role of platelet geometry and organic matrix

To explore the differences in mechanical behavior of nacre between shells that live in different water depths, the microstructures, phase composition and related mechanical properties of nacre under indentation, three-point bending and shear tests in deep-sea Nautilus and freshwater Cristaria plicata shells were systematically investigated. It is found that the nacreous structure in Nautilus shell exhibits an outstanding combination of high strength and high toughness compared with that in C. plicata shell, attributing to its larger aspect ratio of platelet and interfacial shear resistance. Specifically, the interfacial resistance is mainly generated from the adhesion of organic matrix and friction caused by nano-asperities on platelet surfaces. According to the interfacial resistance model, the stiction force originated from organic matrix adhesion is sensitive to its content, and the friction force produced by nano-asperities presents a positive correlation with their distribution density and dimension. Hence, the higher content of organic matrix of nacre with denser and larger nano-asperities on platelet surfaces in Nautilus shell contributes to a higher interfacial resistance. Therefore, it is the coupled effects of platelet geometries (i.e. aspect ratio and nano-asperity) and organic matrix that result in the high-strength and high-toughness nacreous structure in Nautilus shell, which is thus more conductive to inhabit in the deep sea with extremely high pressure. The present research findings are expected to provide beneficial references for the design of strong and tough nacre-inspired materials with appropriate platelet geometry and content of soft phase.

Forty-thousand years of maritime subsistence near a changing shoreline on Alor Island (Indonesia)

We report archaeological findings from a significant new cave site on Alor Island, Indonesia, with an in situ basal date of 40,208–38,454 cal BP. Twenty thousand years older than the earliest Pleistocene site previously known from this island, Makpan retains dense midden deposits of marine shell, fish bone, urchin and crab remains, but few terrestrial species; demonstrating that protein requirements over this time were met almost exclusively from the sea. The dates for initial occupation at Makpan indicate that once Homo sapiens moved into southern Wallacea, settlement of the larger islands in the archipelago occurred rapidly. However, the Makpan sequence also suggests that the use of the cave following initial human arrival was sporadic prior to the terminal Pleistocene about 14,000 years ago, when occupation became intensive, culminating in the formation of a midden. Like the coastal sites on the larger neighbouring island of Timor, the Makpan assemblage shows that maritime technology in the Pleistocene was highly developed in this region. The Makpan assemblage also contains a range of distinctive personal ornaments made on Nautilus shell, which are shared with sites located on Timor and Kisar supporting connectivity between islands from at least the terminal Pleistocene. Makpan’s early inhabitants responded to sea-level change by altering the way they used both the site and local resources. Marine food exploitation shows an initial emphasis on sea-urchins, followed by a subsistence switch to molluscs, barnacles, and fish in the dense middle part of the sequence, with crabs well represented in the later occupation. This new record provides further insights into early modern human movements and patterns of occupation between the islands of eastern Nusa Tenggara from ca. 40 ka.