High Energy Absorption Efficiency Research Articles

Design of hierarchical multi-cell double circular tubes thin-walled structures for energy absorption

This study aims to investigate the crashworthiness performance of a novel hierarchical multi-cell double circular tubes (HMDC) structure under axial impact. Various dual-tube structures of different cross-sections were designed. The effects of hierarchical order, peak number of the core column, and inner circle diameter on the structure were analyzed using Abaqus finite element analysis. The results indicate that in dual-tube structures, replacing the traditional multi-cell structure with a hierarchical multi-cell structure in the interlayer significantly improves energy absorption (EA) characteristics. With the inner circle diameter of the HMDC fixed at 20 mm, the ratio of mean crushing force (MCF) to peak crushing force at the third order increased by 70.70% and 35.68% compared to the first and second orders, respectively. Experimental results and finite element results show that the initial peak value differed by 1.47%, indicating a close match between the experimental and simulation results. The parametric study shows that the inner circle diameter and the peak number of the core column significantly affect EA. The findings of this study provide effective guidance for designing multi-cell dual circular tubes with high EA efficiency.

Crashworthiness Analysis of Bio-Inspired Fractal Plant Stems Multi-Cell Circular Tubes

A novel structure resembling plant stems, termed bio-inspired fractal plant stems multi-cellular circular tubes (BFPMC), was developed by incorporating fractal plant stem characteristics into smaller circular tubes within larger ones. The crashworthiness of this structure under axial impact was investigated using a validated LS-DYNA finite element model. The energy absorption performance of BFPMC tubes, varying in the number of branches, fractal orders, and inner circular diameters, was numerically studied. The numerical findings reveal a 19.27% increase in specific energy absorption (SEA) for BFPMC with [Formula: see text][Formula: see text]mm compared to [Formula: see text][Formula: see text]mm, indicating that filling a single circular tube can enhance the structure’s impact resistance. Subsequently, structural parameters conducive to excellent energy absorption characteristics were determined for various combinations of a number of branches, fractal order, and inner circle diameter parameters. These results offer valuable insights for designing multi-cellular double tubes with high energy absorption efficiency.

Bi-material multistable auxetic honeycombs with reusable and enhanced energy-absorbing phases under in-plane crushing

The ideal energy absorption structures, in addition to possessing reusability and high energy absorption efficiency, should also possess multiple desired properties to fulfill various functional applications. In this study, a bi-material multistable auxetic honeycomb (BMAH) is fabricated by using bi-material 3D printing technology. Under in-plane crushing, multiple stress plateaus can be achieved and the Poisson's ratio can be stably tuned, allowing for a transition from near-zero to negative and then to positive. The above characteristics are attributed to the specimen's multi-path deformation. The first stress plateau is only associated with recoverable elastic deformation. The second and third stress plateaus, which are 8 times and 17 times higher respectively than the first, are associated with plastic deformation, significantly enhancing energy absorption efficiency. The deformation mechanism is theoretically analyzed, and the effects of geometric parameters on the performance of BMAH are investigated. In addition, the effect of crushing velocity on the crushing behavior of the BMAH is also discussed. As the crushing velocity increases, the total number of stress plateaus transitions from three initially to two and then to one. The developed BMAH exhibits significant potential applications in multi-stage energy absorbers and smart sensors.

Origami-based bidirectional self-locking system for energy absorption

When a periodic cellular structure is subjected to high-intensity loading, lateral splashing can occur, significantly decreasing macro mechanical properties. Periodic structures with self-locking properties can overcome this inherent flaw and achieve excellent performance characteristics, including high energy absorption efficiency. In this regard, thin-walled periodic self-locking dissipative structures have been extensively studied recently. Most existing bend-dominated self-locking dissipative systems are two-dimensional and can only achieve self-locking under specific loading conditions. This paper describes a three-dimensional origami-based bidirectional self-locking system that can achieve self-locking under normal and shear loading. Furthermore, a plastic hinge model revealed the energy absorption mechanism of the origami-based cells, whose specific energy absorption (SEA) is higher than that of other existing bend-dominated self-locking cells. The bidirectional self-locking of the origami-based system was demonstrated through compression, bending and impact tests. This origami-based system has high energy absorption efficiency, and the novel bidirectional self-locking mechanism can significantly broaden the design space for periodic dissipative metamaterials.

Theoretical analysis and crashworthiness optimization of multi-cell Al-CFRP hybrid tube

In this paper, a hybrid thin-walled tube with multiple cells and multiple materials is proposed to achieve lightweight, high energy absorption efficiency, and low cost of structures. Energy absorption characteristics and crushing deformation of the hybrid structures are investigated by experimental testing and numerical analysis. Meanwhile, theoretical prediction models of the mean crushing force for hybrid structures are developed and its accuracy was verified. It is found from the sensitivity analysis that the parameters of the multi-cell structure have significant effects on energy absorption. Furthermore, the multi-objective optimization including surrogate models is performed to obtain optimal crashworthiness of the multi-cell hybrid tube. The same optimal results were obtained using the full factor response mapping optimization algorithm and the non-dominated sorting genetic algorithm with elite strategy algorithm for multi-objective optimization solution. Compared with the original multi-cell hybrid tube and multi-cell pure aluminum (Al) tube, the optimized structure showed an increase of 0.25% and 25.31% in specific energy absorption, an increase of 16% and 77.34% in average crushing force, and an increase of 3.89% and 23.08% in energy absorption efficiency, respectively.

Energy absorption characteristics of stepped multi-cell columns subjected to transverse loading

Automotive bumper beam is a vital component that shields passenger and vehicle from harm and damage generated by catastrophic collapse. Previous investigations on its bending behavior have largely concentrated on multi-cell tubes with the same length, whereas stepped multi-cell structures have received less attention. In this paper, a novel stepped multi-cell configuration is proposed to improve the energy absorption characteristics of thin-walled structures under transverse loading. The finite element method is employed to analyze the crushing behaviors of the stepped multi-cell tubes. The numerical results reveal that the stepped multi-cell structures (SM2 to SM5) can reduce the initial peak force by 23.44–45.91% while increasing the energy absorption capacity, crush load efficiency, and specific energy absorption by 5.87–29.51, 38.29–139.45, and 5.87–29.51%, respectively, when compared to a conventional square tube (M1). In addition, the effects of wall thickness, section width, load angle, punch radius, and punch shape on the bending behaviors and energy absorption characteristics are examined. The results indicate that these factors have a considerable influence on the deformation features of M1 and SM2, which leads to a significant reduction in their bending energy absorption characteristics. These variables have no influence on the deformation modes of SM3, SM4, and SM5, and they present local indentation deformation with a high energy absorption efficiency. Increasing the number of layers improves the comprehensive performance of stepped multi-cell tubes, with SM5 exhibiting the best energy absorption characteristics under transverse loading.

Tunable Metamaterials for Impact Mitigation

AbstractTraditional methods of shielding fragile goods and human tissues from impact energy rely on isotropic foam materials. The mechanical properties of these foams are inferior to an emerging class of metamaterials called plate lattices, which have predominantly been fabricated in simple 2.5‐dimensional geometries using conventional methods that constrain the feasible design space. In this work, additive manufacturing is used to relax these constraints and realize plate lattice metamaterials with nontrivial, locally varying geometry. The limitations of traditional computer‐aided design tools are circumvented and allow the simulation of complex buckling and collapse behaviors without a manual meshing step. By validating these simulations against experimental data from tests on fabricated samples, sweeping exploration of the plate lattice design space is enabled. Numerical and experimental tests demonstrate plate lattices absorb up to six times more impact energy at equivalent densities relative to foams and shield objects from impacts ten times more energetic while transmitting equivalent peak stresses. In contrast to previous investigations of plate lattice metamaterials, designs with nonuniform geometric prebuckling in the out‐of‐plane direction is explored and showed that these designs exhibit 10% higher energy absorption efficiency on average and 25% higher in the highest‐performing design.

Dynamic H-Bond crosslinking strategy to prepare impact-hardening protective materials with tunable negative Poisson's ratio

Protective materials with a wide range of practical applications should exhibit a high energy absorption efficiency and be smart and stress-responsive. Herein, a novel smart protective material was formed from an impact-hardening polymer (IHP), which comprised a branched structure, and polyurethane (PU) with quadruple H-bonding. Notably, the quadruple H-bonding was used to enhance the interaction between the two microphases, thus regulating the negative Poisson's ratio. The value of the reversible softness–stiffness switching effect of this material (UPy-IHP-PU) achieved more than 5000, five times stronger than that of a previously reported linear IHP-PU. In addition, the impact-protective ability did not weaken. As the impact velocity increased, the impact energy absorption efficiency of UPy-IHP-PU also increased, even exceeded 70 % under the impact velocity of 5 m/s, thus demonstrating the ability to efficiently reduce the impact force and extend the buffer time against the strike via the impact-hardening phenomenon. Moreover, an adjustable scale of microphase separation can regulate the negative Poisson's ratio to enhance the impact-hardening phenomenon. The excellent energy dissipation ability and smart stress- and rate-responsiveness indicate the application potentials of UPy-IHP-PU as a future wearable impact-protective sensor.

Damage and energy absorption behavior of CFRP/aluminum hybrid open-section thin-walled columns subjected to quasi-static loading

In this study, the damage and energy absorption behaviors of carbon fiber reinforced plastic (CFRP)/aluminum (Al) hybrid open-section thin-walled columns were explored. The results showed that hybrid columns exhibited tremendous merits for the energy absorption. The CFRP-Al columns could absorb 61.21 % and 44.11 % more energy than the corresponding single CFRP columns and the single Al columns with the same thickness, respectively. Furthermore, the specific energy absorption (SEA) of CFRP-Al columns was 16.29 % and 85.06 % higher than that of the corresponding single CFRP columns and the single Al columns. However, different configurations of hybrid columns underwent various damage and failure processes. In addition to Al-CFRP columns, the open-section thin-walled structure exhibited a positive hybrid interaction effect, which dissipated 45.6 % of the total energy absorption. The Al inner layer absorbed a large amount of energy by inducing the CFRP to undergo large deformation and progressive damage, thus, the CFRP-Al columns and CFRP-Al-CFRP columns dissipated more energy and had a higher energy absorption efficiency. Concurrently, the energy absorption behavior of the hybrid column could be changed by different proportions of 45° layers. The present research on damage and energy absorption mechanisms provides some guidance for the lightweight and crashworthiness design of hybrid open-section thin-walled columns.

Experimental and numerical study of in-plane uniaxial compression response of PU foam filled aluminum arrowhead auxetic honeycomb

PurposeAuxetics metamaterials show high performance in their specific characteristics, while the absolute stiffness and strength are much weaker due to substantial porosity. This paper aims to propose a novel auxetic honeycomb structure manufactured using selective laser melting and study the enhanced mechanical performance when subjected to in-plane compression loading.Design/methodology/approachA novel composite structure was designed and fabricated on the basis of an arrowhead auxetic honeycomb and filled with polyurethane foam. The deformation mechanism and mechanical responses of the structure with different structural parameters were investigated experimentally and numerically. With the verified simulation models, the effects of parameters on compression strength and energy absorption characteristics were further discussed through parametric analysis.FindingsA good agreement was achieved between the experimental and simulation results, showing an evidently enhanced compression strength and energy absorption capacity. The interaction between the auxetic honeycomb and foam reveals to exploit a reinforcement effect on the compression performance. The parametric analysis indicates that the composite with smaller included angel and higher foam density exhibits higher plateau stress and better specific energy absorption, while increasing strut thickness is undesirable for high energy absorption efficiency.Originality/valueThe results of this study served to demonstrate an enhanced mechanical performance for the foam filled auxetic honeycomb, which is expected to be exploited with applications in aerospace, automobile, civil engineering and protective devices. The findings of this study can provide numerical and experimental references for the design of structural parameters.

High energy absorption efficiency and biodegradable polymer based microcellular materials via environmental-friendly CO2 foaming for disposable cushioning packaging

Efficient energy absorption is crucial to ensure full protection on precision electronic devices during transportation. Hence, it is necessary to employ a substantial quantity of cushioning packaging materials, despite their disposable feature and severe environmental pollution impact. Therefore, an urgent need arises to develop a green and environmentally friendly material in its production and full life cycle and to offer high energy absorption for buffer packaging. In this study, two kinds of biodegradable components were selected, including a flexible chain structure to enhance the energy absorption capacity, and a rigid chain structure to provide effective support. By utilizing environmental-friendly supercritical CO2 foaming technology, a fully biodegradable foam was fabricated, which demonstrates great potential as a green buffer packaging material with the following advantages: (1) the material boasts a high energy absorption efficiency of 0.325, providing robust protection against the impact of external forces for precision devices during transportation; (2) its low thermal conductivity shields precision devices from heat shock; (3) as water contact angle exceeding 100°, the material changes from hydrophilic to hydrophobic, guarding against moisture erosion; (4) the introduction of cell structure accelerates the degradation process, further enhancing the material's environmental properties. Consequently, it is evident that the development of this innovative biodegradable material holds significant promise for advancing the existing environmentally friendly packaging material.

Design of High‐Performance Bilayer Solar Evaporator Using Graphene‐Coated Bamboo Prepared by Near‐Infrared Laser‐Induced Carbonization of Polystyrene

Solar seawater evaporation is a sustainable seawater desalination technology. However, how to convert low‐cost waste general plastics into highly efficient photothermal materials remains a challenge. By using the idea of “near‐infrared laser‐induced carbonization” at room temperature and in air atmosphere, polystyrene (PS) can be easily converted into graphene. Bismuth oxide (Bi2O3) catalyst is proven to efficiently convert laser energy into thermal energy and transmit it to the surrounding PS matrix, promoting carbonization. On this basis, by adjusting the catalyst content and the laser energy density per unit area, laser‐induced graphene (LIG) materials with high specific surface area, fast water transport, and high solar energy absorption efficiency can be obtained. Furthermore, the LIG materials are coated on the surface of natural bamboo with a capillary structure. This bilayer evaporation device has an evaporation rate of 1.51 kg m−2 h−1 and an energy conversion efficiency of 87.1% under irradiation of 1 sun. This work not only reveals the possibility of preparing high‐value‐added graphene materials from waste general‐purpose plastics, but also proves the application prospects of LIG materials in the field of solar seawater evaporation. This will provide a feasible approach for promoting the development of carbonization of waste general plastics.

Energy absorption of a bio-inspired cylindrical sandwich structure

This research investigates the energy absorption capability of a new bio-inspired cylindrical sandwich structure (BCSS). The sandwich core of the BCSS is designed to mimic the skeletal system of deep-sea glass sponge, which has a square lattice architecture reinforced by diagonal bracings. In this study, energy absorption characteristics are numerically evaluated, with results compared to those of conventional cylindrical sandwich structures with typical lattice and foam cores. It is found that the BCSS has significantly higher energy absorption capacity. In detail, the specific energy absorption of the BCSS is 31.2 %, 18.1 % and 24.4 % higher than those of conventional cylindrical sandwich structures with the kagome, square and foam cores, respectively. Furthermore, a parametric study is performed which reveals that the cell number and the wall thickness of both the core and the skins are key factors determining the energy absorption capacity of the BCSS. Finally, a theoretical derivation is developed to conveniently predict the mean crushing force of the BCSS. This research sheds light on using biomimetic approaches to design an advanced composite structure with high energy absorption efficiency.

Investigation of Structural Energy Absorption Performance in 3D-Printed Polymer (Tough 1500 Resin) Materials with Novel Multilayer Thin-Walled Sandwich Structures Inspired by Peano Space-Filling Curves.

Inspired by Peano space-filling curves (PSCs), this study introduced the space-filling structure design concept to novel thin-walled sandwich structures and fabricated polymer samples by 3D printing technology. The crushing behaviors and energy absorption performance of the PSC multilayer thin-walled sandwich structures and the traditional serpentine space-filling curve (SSC) multilayer thin-walled sandwich structures were investigated using quasi-static compression experiments and numerical analysis. Taking the initial peak crushing force (IPF), specific energy absorption (SEA), and crushing force efficiency (CFE) as evaluation criteria, the effects of geometric parameters, including the curve order, layer height, septa thickness, and wall thickness, on energy absorption performance were comprehensively examined. The results indicated that the energy absorption capacity of the PSC structure was significantly enhanced due to its complex hierarchy. Specifically, the second-order PSC structure demonstrated a 53.2% increase in energy absorption compared to the second-order SSC structure, while the third-order PSC structure showed more than a six-fold increase in energy absorption compared to the third-order SSC structure. Furthermore, a multi-objective optimization method based on the response surface method and the NSGA-II algorithm were employed to optimize the wall thickness and layer height of the proposed novel PSC structures. The optimal solutions suggested that a reasonable wall thickness and layer height were two important factors for designing PSC structures with better energy absorption performance. The findings of this study provide an effective guide for using the space-filling concept with Peano curves for the design of a novel polymer thin-walled energy absorber with high energy absorption efficiency.

Bamboo-inspired hierarchical microlattice structures (BHMSs) for high strength and energy absorption

Mechanical metamaterials as a category of lightweight materials have exhibited superior specific mechanical properties and energy absorption. However, lack of reasonable structural design always results in weakening or failure to achieve the optimal mechanical performance of metamaterials. Here, we firstly adopted bio-inspired and structural optimization methods to guideline the design of microlattice structures. Inspired by the strong and ductile ‘Moso’ bamboo, three bamboo-inspired hierarchical microlattice structures (BHMSs) were initially designed, and the bamboo’s features, viz., hollow, gradient distribution, and cellular, were imitated by designed BHMSs. Optimization design with the objective of maximum ratio of strain energy and reaction force was carried out to furthermore improve the mechanical properties of BHMSs. Afterwards, the optimal BHMSs were printed via Stereolithography. The compressive responses of BHMSs were elaborated by experiments and simulation. Results show that these designed biomimetic structures can be easily tailored via tuning the geometric sizes of unit cell, achieving high compressive specific modulus and strength 48.16 kPa m3 kg−1 and 1389.23 Pa m3 kg−1 and the energy-absorbing efficient 85.43% in the octet bamboo-inspired hierarchical microlattice structures (OCT BHMSs). The design strategies and findings shed light on the realization of advanced metamaterials with tailored mechanical properties. How to design ordered cellular structures for lightweight structures with high mechanical strength and energy absorption efficiency remains a crucial challenge in automation, aerospace and lightweight construction fields. Inspired by the lightweight and high load-bearing capacity of nature bamboos and metamaterials in the previous researches (Song et al., Materials & Design, 2019, 173: 107773; Song et al., International Journal of Fatigue, 2017, 100: 126), here a comprehensive approach of bionics and optimization was proposed to design hierarchical microlattice structures with lightweight, good mechanical properties and high energy absorption efficiency. The bamboo’s characteristics, including hollow, gradient enhancement, and cellular, were completely copied to reasonably produce hierarchical microlattice configurations, while the optimal sizes were obtained though the optimization design.

An origami-inspired design of highly efficient cellular cushion materials

Current architectured cellular cushion materials rely mainly on damage and/or unpredictable collapse of their unit cells to absorb and dissipate energy under impact. This prevents shape recovery and produces undesirable force fluctuations that limit reusability and reduce energy absorption efficiency. Here, we propose to combine advanced manufacturing technologies with Origami principles to create a new class of architectured cellular viscoelastic cushion material which combines low weight and high energy absorption efficiency with damage resistance and full behavior customization. Each unit cell in the proposed material is inspired by the Kresling Origami topology, which absorbs impact energy by gracefully folding the different interfaces forming the cell to create axial and rotational motions. A large part of the absorbed energy is then dissipated through viscoelasticity and friction between the interfaces. The result is a nearly ideal cushion material exhibiting high energy absorbing efficiency (∼ 70%) combined with high energy dissipation (94% of the absorbed energy). The material is also tunable for optimal performance, reliable despite successive impact events, and achieves full shape recovery.

Strategic dual laser 3D printing of structural metal-plastic hybrid materials

Metal-plastic hybrids are emerging as a new challenge in multi-material 3D printing. Here, we provide a novel printing method for strategically bonding and printing metal-plastic hybrids using dual lasers with different wavelengths in a single integrated process. This bottom-up process enables three-dimensional freeform deposition while creating an ideal metal-plastic interface. In particular, our research has shown that the strategic selection of a laser with high energy absorption efficiency for the target material is a key technology for material hybridization. It was revealed that the laser, when irradiated directly onto the interface, partially crosslinks the plastic to form dense phases and induces a chemical reaction with oxygen active species on the metal surface, e.g., an intermediate oxide layer of Al–O–C, leading to the formation of a strong metal-plastic interface. Interestingly, this laser-induced metal-plastic interface, sophisticatedly controlled at the monolayer thickness level, exhibited a distinctive near-interface failure mechanism that developed crack paths along the near interface. Moreover, the competition between crack propagation and pore coalescence in each dense and porous printed layer formed a synergetic interphase, resulting in strong and tough mechanical functions. Our findings can guide the development of metal-plastic hybrids for a variety of industrially important applications.

Strain-Hardening, impact protective and Self-Healing supramolecular polyurethane nanocomposites enabled by quadruple H-Bonding, disulfide bonds and nanoparticles

Developing protective materials with intelligent and stimuli-responsive properties is indispensable for safety protection. However, combining contradictory characteristics into a single polymer is challenging, such as high mechanical strength, impact protection, and self-healing properties. Herein, a strain-hardening supramolecular polyurethane nanocomposite (SPN) with high mechanical strength and unique impact protection characteristics is synthesized by incorporating quadruple hydrogen bonds (H-bonds), disulfide bonds, and modified silica nanoparticles into polyurethane elastomer. Benefiting from the dynamic break and re-form characteristic of quadruple H-bonds and the stress dissipation behavior of nanoparticles, SPN exhibits high energy absorption efficiency and impact protection properties. During the drop ball striking test, the impact energy absorption efficiencies reached 90%, and the buffer time of impact was significantly longer than common buffering materials. The SPN exhibited excellent stretchability and self-healing ability, ascribing to disulfide metathesis and H-bonds association. Moreover, the prepared SPN could be easily processed through a hot press and showed negligible creeping. The developed SPN could serve as a novel self-standing impact protective material that offers promising prospects in sports, transportation, and aerospace fields.

Investigation of the Effect of PbO Doping on Telluride Glass Ceramics as a Potential Material for Gamma Radiation Shielding.

The purpose of this paper is to study the effect of PbO doping of multicomponent composite glass-like ceramics based on TeO2, WO3, Bi2O3, MoO3, and SiO2, which are one of the promising materials for gamma radiation shielding. According to X-ray diffraction data, it was found that the PbO dopant concentration increase from 0.10 to 0.20-0.25 mol results in the initialization of the phase transformation and structural ordering processes, which are expressed in the formation of SiO2 and PbWO4 phases, and the crystallinity degree growth. An analysis of the optical properties showed that a change in the ratio of the contributions of the amorphous and ordered fractions leads to the optical density increase and the band gap alteration, as well as a variation in the optical characteristics. During the study of the strength and mechanical properties of the synthesized ceramics, depending on the dopant concentration, it was found that when inclusions in the form of PbWO4 are formed in the structure, the strength characteristics increase by 70-80% compared to the initial data, which indicates the doping efficiency and a rise in the mechanical strength of ceramics to external influences. During evaluation of the shielding protective characteristics of the synthesized ceramics, it was revealed that the formation of PbWO4 in the structure results in a rise in the high-energy gamma ray absorption efficiency.

Energy absorption characteristics of bio-inspired hierarchical multi-cell bi-tubular tubes

Previous studies have shown that the multi-cell bi-tubular tubes exhibit superior energy absorption compared to the multi-cell tubes. To further improve the energy absorption of the multi-cell bi-tubular tubes, in this study, we propose new bio-inspired hierarchical multi-cell bi-tubular (BHMB) tubes mimicking the tree-like structures in nature. Unlike the conventional multi-cell bi-tubular tubes, the webs in the BHMB are innovatively constructed based on the tree-like structures found in natural structures such as giant water lily leaves. The energy absorption performances of the BHMB tubes with different hierarchical orders, inner diameters and loading angles are numerically investigated. The results demonstrate that the specific energy absorption (SEA) increases with the hierarchical order and inner diameters, and the SEA of the 2nd order BHMB tube is about 55% and 81% higher than that of the conventional multi-cell circular tube and circular tube under axial loading, respectively; 46% and 72% higher under oblique loading with the loading angle of 10°. A theoretical analysis based on the simplified super folding element theory is also developed to determine the mean crushing force (MCF) of the proposed BHMB tubes. The theoretical predictions of the MCF agree well with the numerical results. The findings of this study provide an effective guide for the design of multi-cell bi-tubular tubes with high energy absorption efficiency.