Bio-inspired Structures Research Articles

Crashworthiness analysis and optimization of brain-coral-inspired multilayer sandwich structures under axial crushing

Inspired by brain corals and cuttlebone, this study employed 3D printing technology to fabricate a novel bio-inspired multilayer sandwich structure based on the Hilbert space-filling curve (named BHSS). The mechanical behavior and deformation process of the BHSS were compared through quasi-static axial crushing experiments and finite element (FE) simulations. The energy absorbing characteristics of the BHSS with different layers were compared through FE simulations, and the results indicated that the 4-layer BHSS displayed superior crashworthiness. Then, parametric studies were conducted to investigate the influence of layer-height gradient and wall-thickness gradient on the energy absorption performance and deformation modes of the BHSS. It was confirmed that the double gradient designs significantly reduced the initial peak force and improved the specific energy absorption of the BHSS. Finally, the multi-objectives optimization based on response surface method and the non-dominated sorting genetic algorithm (NSGA-II) was employed to optimize the geometric parameters of the BHSS, aiming at the optimal configuration for better crashworthiness. Compared to the original design structure, the SEA of the optimized knee point structure was increased by 21.8% and the IPF was reduced by 72.6%. These findings provided valuable guidelines for the brain-coral-inspired design of multilayer sandwich structures with superior energy-absorbing performance.

Implementation of bio-inspired organic/inorganic layer structures as interphase in carbon fiber reinforced concrete

Biological materials found in nacre or glass sponges reveal specific layered organic and inorganic structures known for their fracture toughness caused by crack deflection and bridging. This work aims to bio-mimic the brick-and-mortar (BnM) structure from nacre and the layer-by-layer (LbL) structure from the glass sponge filaments to incorporate these effects into the contact zone of carbon fiber-reinforced concrete (CFRC) in order to prevent brittle composite failure. To build up BnM- and LbL-structure materials such as nanoclays, sodium water glass, and polymer dispersions were selected since they are well-established low-cost materials in building. Nanoclays were analyzed regarding their size, dispersibility and exfoliation. Montmorillonite (MMT) was used to be mixed with polymers to produce self-assembled BnM-structured films and coatings. Also, LbL-structures were formed by alternating layers of sodium water glass and polymer. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to verify the morphology. The MMT-containing coatings demonstrated enhanced nucleation potential when exposed to cementitious eluate. Micromechanical pull-out tests on single carbon fibers with BnM- and LbL-coatings embedded in concrete demonstrate the potential to increase composite toughness. The successful implementation of the bio-inspired structures using affordable materials lays the groundwork for their scalability and integration into composite structures for building.

Nested structure role in the mechanical response of spicule inspired fibers

Euplectella aspergillum marine sponge spicules are renowned for their remarkable strength and toughness. These spicules exhibit a unique concentric layering structure, which contributes to their exceptional mechanical resistance. In this study, finite element method simulations were used to comprehensively investigate the effect of nested cylindrical structures on the mechanical properties of spicules. This investigation leveraged scanning electron microscopy images to guide the computational modeling of the microstructure and the results were validated by three-point bending tests of 3D-printed spicule-inspired structures. The numerical analyses showed that the nested structure of spicules induces stress and strain jumps on the layer interfaces, reducing the load on critical zones of the fiber and increasing its toughness. It was found that this effect shows a tapering enhancement as the number of layers increases, which combines with a threshold related to the 3D-printing manufacturability to suggest a compromise for optimal performance. A comprehensive evaluation of the mechanical properties of these fibers can assist in developing a new generation of bioinspired structures with practical real-world applications.

Bioinspired on-off switchable multi-level responsiveness for ultralong fire-warning, super-sensitive solvent/humidity and light-driven behaviors

The prospects of endowing the omnipresent hazardous substances with sensitive, safe, and stable life-like behaviors poses significant for the development of on–off switchable smart materials. Herewith, based on material-structural synergistic design, a multi-level responsiveness smart structures (VBGO) inspired by phospholipid biomolecules is self-assembled through asymmetric swelling and smart supramolecular nano-structures. Due to the outstanding sensitive of fire-warning nano-hybrid of functionalized cyclodextrin-graphene and highly stable substrate of vermiculite, the designed VBGO exhibits the high-sensitively fire alarm time (only 0.17 s) and super-along sustained fire alarm time (up to 249 s). Moreover, the VBGO displays significant increment in thermal stability and film-forming properties. Besides, given the asymmetrical and self-assembled smart structures, the VBGO exhibits the unique fast responses in their surrounding environments like fire, heat, light, humidity, and solvent vapor. Additionally, the on–off switchable mechanisms of fire-warning responsiveness, solvent-/humidity-/light-driven, shape memory and environmental awareness are presented systematically. This work introduces a sensitive, safe, and stable approach to designing multi-level responsive smart materials by modifying fire-warning bioinspired structures.

Bio-inspired mobile robot design and autonomous exploration strategy for underground special space

PurposeTo make the robot that have real autonomous ability is always the goal of mobile robot research. For mobile robots, simultaneous localization and mapping (SLAM) research is no longer satisfied with enabling robots to build maps by remote control, more needs will focus on the autonomous exploration of unknown areas, which refer to the low light, complex spatial features and a series of unstructured environment, lick underground special space (dark and multiintersection). This study aims to propose a novel robot structure with mapping and autonomous exploration algorithms. The experiment proves the detection ability of the robot.Design/methodology/approachA small bio-inspired mobile robot suitable for underground special space (dark and multiintersection) is designed, and the control system is set up based on STM32 and Jetson Nano. The robot is equipped with double laser sensor and Ackerman chassis structure, which can adapt to the practical requirements of exploration in underground special space. Based on the graph optimization SLAM method, an optimization method for map construction is proposed. The Iterative Closest Point (ICP) algorithm is used to match two frames of laser to recalculate the relative pose of the robot, which improves the sensor utilization rate of the robot in underground space and also increase the synchronous positioning accuracy. Moreover, based on boundary cells and rapidly-exploring random tree (RRT) algorithm, a new Bio-RRT method for robot autonomous exploration is proposed in addition.FindingsAccording to the experimental results, it can be seen that the upgraded SLAM method proposed in this paper achieves better results in map construction. At the same time, the algorithm presents good real-time performance as well as high accuracy and strong maintainability, particularly it can update the map continuously with the passing of time and ensure the positioning accuracy in the process of map updating. The Bio-RRT method fused with the firing excitation mechanism of boundary cells has a more purposeful random tree growth. The number of random tree expansion nodes is less, and the amount of information to be processed is reduced, which leads to the path planning time shorter and the efficiency higher. In addition, the target bias makes the random tree grow directly toward the target point with a certain probability, and the obtained path nodes are basically distributed on or on both sides of the line between the initial point and the target point, which makes the path length shorter and reduces the moving cost of the mobile robot. The final experimental results demonstrate that the proposed upgraded SLAM and Bio-RRT methods can better complete the underground special space exploration task.Originality/valueBased on the background of robot autonomous exploration in underground special space, a new bio-inspired mobile robot structure with mapping and autonomous exploration algorithm is proposed in this paper. The robot structure is constructed, and the perceptual unit, control unit, driving unit and communication unit are described in detail. The robot can satisfy the practical requirements of exploring the underground dark and multiintersection space. Then, the upgraded graph optimization laser SLAM algorithm and interframe matching optimization method are proposed in this paper. The Bio-RRT independent exploration method is finally proposed, which takes shorter time in equally open space and the search strategy for multiintersection space is more efficient. The experimental results demonstrate that the proposed upgrade SLAM and Bio-RRT methods can better complete the underground space exploration task.

Concept-based Extension of SKOS Defense Controlled Vocabulary: Techniques and Implications

A controlled vocabulary is a set of terms that are utilized to represent knowledge in a domain. In the domain of defense, the use of terms such as “command, control, communications, computers, intelligence, surveillance and reconnaissance (C4ISR)”, “armored personnel carriers (APC)”, or “biological and bioinspired structures for multispectral surveillance” denote the core competencies of domain experts and the depth of diverse knowledge. This paper describes the second phase of the pilot project to create a defense-related controlled vocabulary with a focus on the Russo-Ukraine conflict. Applications for data annotation, SKOS hierarchical vocabulary development, and vocabulary quality analysis are used to identify terms in text, express identified terms in military press releases as SKOS vocabulary, and assess its structure. The preliminary vocabulary is extended by 173 concepts. The quality of the vocabulary is validated against a SKOS checker of twenty-four criteria.

Seahorse-Tail-Inspired Soft Pneumatic Actuator: Development and Experimental Characterization.

The study of bio-inspired structures and their reproduction has always fascinated humans. The advent of soft robotics, thanks to soft materials, has enabled considerable progress in this field. Over the years, polyps, worms, cockroaches, jellyfish, and multiple anthropomorphic structures such as hands or limbs have been reproduced. These structures have often been used for gripping and handling delicate objects or those with complex unknown a priori shapes. Several studies have also been conducted on grippers inspired by the seahorse tail. In this paper, a novel biomimetic soft pneumatic actuator inspired by the tail of the seahorse Hippocampus reidi is presented. The actuator has been developed to make a leg to sustain a multi-legged robot. The prototyping of the actuator was possible by combining a 3D-printed reinforcement in thermoplastic polyurethane, mimicking the skeletal apparatus, within a silicone rubber structure, replicating the functions of the external epithelial tissue. The latter has an internal channel for pneumatic actuation that acts as the inner muscle. The study on the anatomy and kinematic behaviour of the seahorse tail suggested the mechanical design of the actuator. Through a test campaign, the actuator prototype was characterized by isotonic tests with an external null load, isometric tests, and activation/deactivation times. Specifically, the full actuator distension of 154.5 mm occurs at 1.8 bar, exerting a maximum force of 11.9 N, with an activation and deactivation time of 74.9 and 94.5 ms, respectively.

High throughput automated characterization of enamel microstructure using synchrotron tomography and optical flow imaging

The remarkable damage-tolerance of enamel has been attributed to its hierarchical microstructure and the organized bands of decussated rods. A thorough characterization of the microscale rod evolution within the enamel is needed to elucidate this complex structure. While prior efforts in this area have made use of single particle tracking to track a single rod evolution to various degrees of success, such a process can be both computationally and labor intensive, limited to the evolution path of a single rod, and is therefore prone to error from potentially tracking outliers. Particle image velocimetry (PIV) is a well-established algorithm to derive field information from image sequences for processes that are time-dependent, such as fluid flows and structural deformation. In this work, we demonstrate the use of PIV in extracting the full-field microstructural distribution of rods within the enamel. Enamel samples from a wild African lion were analyzed using high-energy synchrotron X-ray micro-tomography. Results from the PIV analysis provide sufficient full-field information to reconstruct the growth of individual rods that can potentially enable rapid analysis of complex microstructures from high resolution synchrotron datasets. Such information can serve as a template for designing damage-tolerant bioinspired structures for advanced manufacturing. Statement of significanceThorough characterization and analysis of biological microstructures (viz. dental enamel) allows us to understand the basis of their excellent mechanical properties. Prior efforts have successfully replicated these microstructures via single particle tracking, but the process is computationally and labor intensive. In this work, optical flow imaging algorithms were used to extract full-field microstructural distribution of enamel rods from synchrotron X-ray computed tomography datasets, and a field method was used to reconstruct the growth of individual rods. Such high throughput information allows for the rapid production/prototyping and advanced manufacturing of damage-tolerant bioinspired structures for specific engineering applications. Furthermore, the algorithms used herein are freely available and open source to broaden the availability of the proposed workflow to the general scientific community.

Super-Toughness Carbon Nanotube Yarns by Bio-Inspired Nano-Coiling Engineering.

Lightweight structural materials are commonly used as effective fillers for advanced composites with high toughness. This study focused on enhancing the toughness of direct-spun carbon nanotube yarns (CNTYs) by controlling the micro-textural structure using a water-gap-based direct spinning. Drawing inspiration from the structural features of natural spider silk fibroin, characterized by an α-helix in the amorphous region and β-sheet in the crystalline region, multiscale bundles within CNTYs are reorganized into a unique nano-coil-like structure. This nano-coiled structure facilitated the efficient dissipation of external mechanical loads through densification with the rearrangement of multiscale bundles, improving specific strength and strain. The resulting CNTYs exhibited exceptional mechanical properties with toughness reaching 250Jg-1, making them promising alternatives to commercially available fibers in lightweight, high-toughness applications. These findings highlight the significance of nano-coiling engineering for emulating bio-inspired micro-textural structures, achieving remarkable enhancement in the toughness of CNTYs.

Studies on effect of failure modes on mechanical properties of staggered composites

Biological materials such as bone, nacre, antler, and teeth are gifted with excellent mechanical properties that have inspired the development of synthetic composites. These superior properties are attributed to the geometrical as well as the material properties of the constituents at a small scale. This paper is focused on the influence of failure modes over the mechanical properties including stiffness, strength, and toughness, after the failure of different interfaces in staggered bio-inspired structures such as regular and stairwise staggered arrangements where stiff platelets are embedded in a pliant matrix. In order to find these properties, this article develops a novel analytical model for stress transfer and effective Young’s modulus of a stairwise staggered composite based on composite micro-mechanics principles. The results indicate that the failure sequence indeed influences mechanical characteristics such as stiffness, strength, and toughness. Also, the results from the present study is capable of quantifying the major contribution of toughness that is obtained from the vertical interface failure, which is ignored in previous studies for estimating the toughness. The results indicate that a toughness contribution as high as 56% from the inclusion of the first failure can be obtained in a stairwise staggered composite. The influence of significant parameters like Young’s moduli ratio between the platelet and matrix ( Ep/Em ) over the strength at different modes of failure showed that the strength at first and second failures increases as the Ep/Em ratio increases. The findings of this study hold significant potential for predicting the failure sequences with their quantified contributions towards the mechanical properties of a bio-inspired staggered composite.

Bioinspired 3D‐Printed Auxetic Structures with Enhanced Fatigue Behavior

Recently, auxetic metastructures have gained considerable attention in various fields of study due to their unique characteristics. This study aims to design and fabricate bioinspired auxetic structures and comprehensively investigate the static and dynamic mechanical properties of those architectures under tensile and compressive loads. A comparative analysis is carried out with a conventional structure, considering static tensile and compressive tests, as well as dynamic tension–tension and compression–compression assessments. Experimental measurements and finite‐element analysis are utilized to evaluate various parameters of the scaffolds, such as Young's modulus, yield strength, energy absorption, stress distribution, Poisson's ratio, and fatigue properties. The findings reveal that bioinspired auxetic structures can appropriately mimic the physical attributes and stress–strain characteristics of human tissue, such as the Achilles tendon. Furthermore, these bioinspired auxetic structures significantly enhance the cycles to failure compared to conventional structures, accompanied by notable improvements in energy absorption. Among the auxetic structures, the star configuration exhibits remarkable tolerance to tensile fatigue loads, while the sharp sinus structure demonstrates the highest tolerance to cycles to failure under compression–compression loads. The static and fatigue properties of bioinspired auxetic structures indicate their potential for biomedical applications.

A sensor system integrating sensing and intelligence based on MEMS reservoir computing

Reservoir computing (RC) is a bio-inspired neural network structure which is easy to be implemented in hardware. It has been constructed in a great many fields such as memristor, electrochemical reaction, among which MEMS is the closest to integrate sensing and computing. We propose a novel sensor system of MEMS RC based on stiffness modulation, that natural signal directly affects the system stiffness as the input. Under this paradigm, information can be processed locally without data collection and pre-processing. We inherited the nonlinearity tuning principle and optimized the post-processing algorithm by creating a digital mask operator. In this way, the system can deal with classification tasks as well as forecasting tasks. We integrated MEMS, IC and FPGA with a small volume and low power consumption, so complicated setup for data discretization and transduction in traditional MEMS RC is eliminated. The system can process word classification and chaos forecasting with high accuracy, which preliminarily proves the integrated RC architecture.

Bioinspired and Multifunctional Tribological Materials for Sliding, Erosive, Machining, and Energy-Absorbing Conditions: A Review.

Friction, wear, and the consequent energy dissipation pose significant challenges in systems with moving components, spanning various domains, including nanoelectromechanical systems (NEMS/MEMS) and bio-MEMS (microrobots), hip prostheses (biomaterials), offshore wind and hydro turbines, space vehicles, solar mirrors for photovoltaics, triboelectric generators, etc. Nature-inspired bionic surfaces offer valuable examples of effective texturing strategies, encompassing various geometric and topological approaches tailored to mitigate frictional effects and related functionalities in various scenarios. By employing biomimetic surface modifications, for example, roughness tailoring, multifunctionality of the system can be generated to efficiently reduce friction and wear, enhance load-bearing capacity, improve self-adaptiveness in different environments, improve chemical interactions, facilitate biological interactions, etc. However, the full potential of bioinspired texturing remains untapped due to the limited mechanistic understanding of functional aspects in tribological/biotribological settings. The current review extends to surface engineering and provides a comprehensive and critical assessment of bioinspired texturing that exhibits sustainable synergy between tribology and biology. The successful evolving examples from nature for surface/tribological solutions that can efficiently solve complex tribological problems in both dry and lubricated contact situations are comprehensively discussed. The review encompasses four major wear conditions: sliding, solid-particle erosion, machining or cutting, and impact (energy absorbing). Furthermore, it explores how topographies and their design parameters can provide tailored responses (multifunctionality) under specified tribological conditions. Additionally, an interdisciplinary perspective on the future potential of bioinspired materials and structures with enhanced wear resistance is presented.

A Parameter Reduction-Based Decision-Making Method with Interval-Valued Neutrosophic Soft Sets for the Selection of Bionic Thin-Wall Structures.

Bio-inspired thin-wall structures with excellent mechanical properties, high-energy absorption capabilities, and a desirable lightweight level have been extensively applied to the passive safety protection of transportation and aerospace. Collaboration matching and the selection of optional structures with different bionic principles considering the multiple attribute evaluation index and engineering preference information have become an urgent problem. This paper proposes a parameter reduction-based indifference threshold-based attribute ratio analysis method under an interval-valued neutrosophic soft set (IVNS-SOFT) to obtain the weight vector of an evaluation indicator system for the selection of bionic thin-wall structures, which can avoid the problem of an inadequate subjective evaluation and reduce redundant parameters. An IVNS-SOFT-based multi-attributive border approximation area comparison (MABAC) method is proposed to obtain an optimal alternative, which can quantify uncertainty explicitly and handle the uncertain and inconsistent information prevalent in the expert system. Subsequently, an application of five bio-inspired thin-wall structures is applied to demonstrate that this proposed method is valid and practical. Comparative analysis, sensitivity analysis, and discussion are conducted in this research. The results show that this study provides an effective tool for the selection of bionic thin-wall structures.

How can research on modern and fossil bones help us build more resistant columns?

Bone is an economical material. Indeed, as moving a heavy skeleton is energetically costly, the vertebrate skeleton is adapted to maximise resistance to the stresses imposed with a minimum amount of material, so that bone tissue is deposited where it is needed. Using bone as a source of inspiration should therefore reduce the manufacturing cost (both financial and ecological) and increase the strength (and lifespan) of bioinspired (BI) structures. This study proposes to investigate which adaptive features of the outer shape and inner structure of bone, related to compressive strength, could be used to build BI support structures. To do so, we explain the choice of the bones to be analysed and present the results of the biomechanical analyses (finite element analysis) carried out on virtual models built from the structures of the different bone models and of the mechanical tests carried out on 3D-printed versions of these models. The compressive strength of these direct bone BI columns was compared with each other, and with those of a conventional filled cylindrical column, and of a cylindrical column whose internal structure is BI from the radius of the white rhinoceros. The results of our comparative analyses highlight that the shape of long bones is less effective than a cylinder in resisting compression but underline the relevance in designing BI cylindrical columns with heterogeneous structures inspired by the radius of the white rhinoceros and the tibia of the Asian elephant, and raise the interest in studying the fossil record using the radius of the giant rhinocerotoid Paraceratherium.

Spatial engineering of single-atom Fe adjacent to Cu-assisted nanozymes for biomimetic O2 activation

The precise design of single-atom nanozymes (SAzymes) and understanding of their biocatalytic mechanisms hold great promise for developing ideal bio-enzyme substitutes. While considerable efforts have been directed towards mimicking partial bio-inspired structures, the integration of heterogeneous SAzymes configurations and homogeneous enzyme-like mechanism remains an enormous challenge. Here, we show a spatial engineering strategy to fabricate dual-sites SAzymes with atomic Fe active center and adjacent Cu sites. Compared to planar Fe–Cu dual-atomic sites, vertically stacked Fe–Cu geometry in FePc@2D-Cu–N–C possesses highly optimized scaffolds, favorable substrate affinity, and fast electron transfer. These characteristics of FePc@2D-Cu–N–C SAzyme induces biomimetic O2 activation through homogenous enzymatic pathway, resembling functional and mechanistic similarity to natural cytochrome c oxidase. Furthermore, it presents an appealing alternative of cytochrome P450 3A4 for drug metabolism and drug–drug interaction. These findings are expected to deepen the fundamental understanding of atomic-level design in next-generation bio-inspired nanozymes.

Designing Lightweight 3D-Printable Bioinspired Structures for Enhanced Compression and Energy Absorption Properties.

Recent progress in additive manufacturing, also known as 3D printing, has offered several benefits, including high geometrical freedom and the ability to create bioinspired structures with intricate details. Mantis shrimp can scrape the shells of prey molluscs with its hammer-shaped stick, while beetles have highly adapted forewings that are lightweight, tough, and strong. This paper introduces a design approach for bioinspired lattice structures by mimicking the internal microstructures of a beetle's forewing, a mantis shrimp's shell, and a mantis shrimp's dactyl club, with improved mechanical properties. Finite element analysis (FEA) and experimental characterisation of 3D printed polylactic acid (PLA) samples with bioinspired structures were performed to determine their compression and impact properties. The results showed that designing a bioinspired lattice with unit cells parallel to the load direction improved quasi-static compressive performance, among other lattice structures. The gyroid honeycomb lattice design of the insect forewings and mantis shrimp dactyl clubs outperformed the gyroid honeycomb design of the mantis shrimp shell, with improvements in ultimate mechanical strength, Young's modulus, and drop weight impact. On the other hand, hybrid designs created by merging two different designs reduced bending deformation to control collapse during drop weight impact. This work holds promise for the development of bioinspired lattices employing designs with improved properties, which can have potential implications for lightweight high-performance applications.

Experimental investigation of 3D printed bio-inspired Xylotus lattice structure for energy absorption under quasi-static axial loading conditions

The demand for robust, lightweight polymer components in various industries has prompted researchers to turn to nature's structures for inspiration. Leveraging Polymer Additive Manufacturing (PAM), specifically Fused Filament Fabrication (FFF), complex bio-inspired lattice polymer structures have been successfully realized. This experimental study focuses on the development of novel 3D printed bioinspired Xylotus lattice structure with elements inspired by xylem and lotus. The primary goal was to evaluate the deformation behaviour and energy absorption characteristics of 3D printed Xylotus lattice structure under quasi-static compressive loading and compare the results with existing research. The hybrid (Xylotus) structure of xylem and lotus exhibited a sequential failure pattern, starting with axial cracks and followed by buckling. Furthermore, an analysis of energy absorption showed that the xylem lattice outperformed the lotus lattice, thanks to its robust tubular elements. Notably, the Xylotus lattice displayed the highest energy absorption capabilities, capitalizing on features from both lotus and xylem. The energy absorption of the Xylotus lattice structure surpassed that of the xylem and lotus structures by 13% and 29.2%, respectively. The xylotus lattice structure exhibited 38% higher energy absorption compared to the existing research. Moreover, the specific energy absorption of the Xylotus lattice structure outperformed the lattice structures reported in the existing research by 37%. This study offers valuable insights into the structural behaviour, energy absorption, and specific energy absorption of bio-inspired lattice Xylotus structure. The findings contribute significantly to the design of resilient, lightweight components, supporting the advancement of bio-inspired structures for diverse applications in various industries.

Mechanical Behavior of Bio-Inspired Honeycomb-Core Composite Sandwich Structures to Low-Velocity Dynamic Loading.

In order to improve the impact resistance of sandwich panels under low-velocity impact, the lotus leaf vein is selected as a biological prototype to design a bio-inspired honeycomb (BIH) sandwich panel. ABAQUS is used to establish and effectively verify the finite element (FE) model of the BIH sandwich panel. To systematically compare and study the mechanical properties of BIH and conventional hexagonal honeycomb sandwich panels under low-velocity impact, the maximum displacement of face-sheets, the deformation mode, the plastic energy consumption and the dynamic response curve of the impact end are presented. At the same time, the performance differences between them are revealed from the perspective of an energy absorption mechanism. Furthermore, the influence of the circumscribed circle diameter ratio of the BIH trunk to branch (γ), the thickness ratio of the trunk to branch (K) and the impact angle (θ) on impact resistance is studied. Finally, the BIH sandwich panel is further optimized by using the response surface method. It can be concluded that, compared to conventional hexagonal honeycomb sandwich panels, the addition of walls in the BIH sandwich panel reduces the maximum deformation of the rear face-sheet by 10.29% and increases plastic energy consumption by 8.02%. Properly adjusting the structural parameters can effectively enhance the impact resistance of the BIH sandwich panel.

Experimental and numerical investigation on novel three-dimensional printed bio-inspired hexagonal lattices for energy absorption and stiffness behavior

In the current study, a new type of novel lattice structures with the concept of bio-mimicking three different nature-inspired designs from the honeycomb patterns, the overlapping phenomenon of the scales present on fish dermal layers, and scutes pattern observed from the top skin layers present on crocodile species are developed. These lattice structures are designed within a cubic volume of 30 mm. The design of lattice unit cells is made with two different geometrical sizes of 4 and 6 mm with different overlapping areas of 20, 30, 40, and 50% calculated from each cell area. All the unit cells’ walls are maintained at 0.4 and 0.6 mm only. The specimens are modeled and manufactured through the VAT photopolymerization process, one of the significant additive manufacturing principles for great dimensional accuracy with negligible defects in 3D printing (3DP). The research approach used to develop lightweight bio-inspired structures has been laid out, starting with observing design that served as inspiration. The cured 3D-printed specimens are examined under quasi-static compressive loading carried out on all specimens as per ASTM 1621 standards to measure the crashworthiness response of designed specimens. The energy ingestion capacity of all the specimens is assessed. A good correlation is observed between the experimental and numerical results for better validation. The best design parameters among all 16 specimens are identified for applying energy absorption applications in the automobile and aviation fields in real-time.