Metamaterial Structure Research Articles

Quasi-static and dynamic behavior analysis of 3D CFRP woven laminated composite auxetic structures for load-bearing and energy absorption applications

This paper investigated the quasi-static and dynamic behavior of 3D auxetic metamaterial structures made from carbon fiber reinforced polymer (CFRP) laminated composite. The aim of the study was to enhance design methodologies for load-bearing and energy absorption applications of these 3D novel structures, filling the research gap in understanding their response to quasi-static and especially dynamic loadings. The two novel 3D structures were designed and fabricated by using an interlocking assembly method based on the 2D auxetic CFRP sheets, which were formed with hybrid double-arrow-head with re-entrant and star unit-cells and made with plain weave carbon epoxy prepregs. The finite element (FE) method was adopted to analyze the mechanical characteristics of the structures under the quasi-static and dynamic loading, and Hashin failure criteria were used to define damage in the structures. The study showed that the designed 3D auxetic CFRP structures simultaneously exhibit superior auxeticity, load-bearing, and energy absorption capacity.

Novel Fast Cure Silicone Inks for Single‐Step, Support‐Free 3D Printing of Tall, Overhanging, and High Aspect Ratio Structures

AbstractSilicone elastomers have a broad variety of applications, such as soft robotics, biomedical devices, and structural metamaterials. The extrusion‐based method known as direct ink write (DIW) has enabled the production of additively manufactured silicone structures. However, this method is limited to manufacturing mostly planar or pseudo‐3D structures. Due to the low self‐supporting capabilities of extruded strands for traditional silicone‐based “inks,” obtaining tall or overhanging structures, or structures comprised by thin walls is not feasible. Here, a novel Fast Cure silicone‐based ink is demonstrated that enables manufacturing of complex 3D structures. The Fast Cure ink is a two‐part mixture and silicone structures are produced by inline mixing and coextrusion of a part containing a catalyst (part A) and a part containing a crosslinker (part B). By the virtue of crosslinking, the extruded strands rapidly rigidize, increasing their self‐supportive capacity. Hence, structures can be obtained with superior shape retention and previously unobtainable parts are realized that are tall, with aspect ratios higher than 3, and have overhanging features, achieving inclination angles smaller than 35° with respect to the printing plane. These minimal sag parts are achieved without requiring extra curing or mechanisms, support structures, or suspension baths.

Low-frequency broadband vibration isolation study of inertial amplification Meta-lattice sandwich structure

In the pursuit of excellent mechanical properties, the realization of lightweight structure has attracted great attention from researchers in recent years. To reduce the mass of structures while providing them with low-frequency, broadband vibration damping and multifunctional integration capabilities, this paper presents the use of a Meta-lattice sandwich structure designed using the inertial amplification mechanism. By utilizing a combination of Bloch boundary conditions and the finite element method, we calculated the band gap of the metamaterial structure through finite element software. Afterwards, we examined the impact of the internal structural dimensions and the angle of the internal core truss on the bandgap of the metamaterial structure, as well as their effects on the load-bearing performance. The results demonstrate that the implementation of the concept of inertial amplification achieves low-frequency broadband vibration damping while decreasing the overall mass of the structure, while also retaining good load-bearing performance.

A metamaterial bone plate for biofixation based on 3D printing technology

Bone plate design and production methods are critical for producing metamaterial bone plates. This study investigated the design and development process of porous structures and metamaterial bone plates for biofixation applications. We designed the porous structures for bone plates using parametric modeling and fused them via the implicit surface fusion method. Likewise, we designed the metamaterial bone plate structure using reverse reconstruction and topological optimization. Thereafter, we utilized three-dimensional (3D) printing for producing and post-processing the metamaterial bone plate. We observed a reduced stress-shielding effect after topological optimization. Additionally, the resultant diamond porous structure maintained a high porosity under pressure. The 3D-printed bone plates and fillers had a bright porous surface, with clear pore structures and good connectivity. The assembly of the 3D-printed femur, bone plate, filler, and standardized screw indicated a good fitting, and the filler could be fixed by the inclined surface. Taken together, the findings of this study established the foundation for the prospective application of metamaterial bone plates in biofixation.

A Review of Metamaterials Cloaking for Military and Civilian Use

Metamaterials cloaking technology boasts a wide array of potential uses, spanning from military stealth applications to advancements in medical imaging. Metamaterials are specially engineered materials with unique characteristics absent in natural substances, such as negative refractive index, empowering them to manipulate electromagnetic waves in novel ways. The process of cloaking with metamaterials involves the bending of light or other electromagnetic waves around an object, effectively rendering it invisible or significantly reducing its detectability. This is accomplished through the intricate design of metamaterial structures capable of governing the flow of electromagnetic fields, diverting them away from the cloaked object. Among the most prominent applications of metamaterial cloaking is the development of invisibility cloaks. While primarily at the experimental stage, researchers have made substantial progress in crafting cloaking devices capable of concealing objects from specific wavelengths of light. These cloaks function by manipulating the path of light around an object, effectively creating the illusion of its absence. The potential applications of metamaterial cloaking encompass a broad spectrum, including invisibility, antennas and sensors, medical imaging, wireless communication, and stealth technology.

Elastic wave suppression through additively manufactured petal lattice metamaterials

Lattice-core sandwich structure metamaterials are lightweight alternatives to monolithic materials that can present better mechanical, thermal, and energy dampening performance. Manufacturing lattice metamaterials to follow curved surfaces can pose a challenge, as the lattices rely on their geometric orientation to the substrate for their mechanical properties. This work rationally designed a lattice structure where the surface is broken up into “petals” connected to the underlying lattice, which localizes the petals’ impact response. This design opens a pathway for implementation of lattice-core sandwich structures onto complex surface geometries. These petal structures were evaluated for their energy absorption efficiency experimentally by utilizing pressure waves generated with nanosecond lasers and computationally via finite element modeling. The lattice structures exhibited a two-orders-of-magnitude decrease in transmitted pressure compared to their constituent steel at equivalent mass. Furthermore, localizing energy absorption into petal structures provided a 44% reduction in peak load compared to a continuous “single-petal” design.

Integrating resistance-based sensing into fused filament fabricated mechanical metamaterial structure

Integrating resistance-based sensing into fused filament fabricated mechanical metamaterial structure

All-optical high-contrast femtosecond switching using nonlinearity from an epsilon-near-zero effect in plasmonic metamaterials.

Metamaterials opened a new realm to control light-matter interactions at sub-wavelength scale by engineering meta-atoms. Recently, the integration of several emerging nonlinear materials with metamaterial structures enables ultra-fast all-optical switching at the nanoscale and thus brings enormous possibilities to realize next-generation optical communication systems. This Letter presents a novel, to the best of our knowledge, design of plasmonic metamaterials for high-contrast femtosecond all-optical switching. We leverage magnetic plasmon (MP) resonance combined with the nonlinear effects of an epsilon-near-zero (ENZ)-material. The proposed design comprises a periodic array of two closely spaced Au-nanogratings deposited on an optically thick Au-substrate to excite MP-resonance. To enable a dynamically tunable resonance, the nanogrooves in meta-atoms are filled with an ENZ-material, cadmium-oxide (CdO). The intraband transition-induced optical nonlinearities in the ENZ-medium are studied using a two-temperature model. The MP-resonance ensures strong light-matter interactions enabling enhancement of the nonlinearities of the proposed structure. We observe that the pump-induced refractive index change in the CdO layer causes a redshift of the MP-resonance dip wavelength in the reflectance spectrum, leading to a high modulation depth of 0.83 at 1.55 µm. With an ultra-fast response time of 776 fs while maintaining a low pump-fluence of 75 µJ/cm2, the proposed metamaterial could help in realizing switches for next-generation optical computation systems.

Accessing quasi-static impact process by 3D-NPR corrugated metamaterials

The conventional impact process is a quintessential impulse process that causes substantial damage due to the high initial impact force. However, the impact effect can be significantly diminished by making the impulse process quasi-statically by using a three-dimensional negative Poisson's ratio corrugated metamaterial (3D-NPRCM) structure. This paper proposes a novel 3D-NPRCM obtained by folding the 2D-NPRCM. This study examines the crashworthiness properties and impact force of 3D-NPRCM subjected to impact using the finite element method (FEM). The results reveal that the sequential matrix structure has the ability to make impact impulse processes quasi-statically. The effects of various folding angles, arrangements, and geometrical parameters on the properties are also explored. Finally, the 3D-NPRCM is employed in an automobile crash box design. Through axial quasi-static compression simulation, the peak crushing force of the 3D-NPRCM crash box is reduced by 25.374 % from 211.652 kN to 157.946 kN, and the energy absorbed is increased by 23.830 % from 11.259 kJ to 13.942 kJ, compared to the conventional crash box. Through cart lateral impact simulation, the peak crushing force of the 3D-NPRCM crash box is reduced by 18.076 % from 206.9 kN to 169.5 kN, and the compressive displacement is decreased by 9.457 % from 235.8 mm to 213.5 mm. This work presents a novel design proposition for a crash box in vehicle engineering and demonstrates a fresh approach to expand the design of three-dimensional mechanical metamaterials.

Bi-functional absorption performance of metamaterial structure based on metallic-square with U-shaped slot

Bi-functional absorption performance of metamaterial structure based on metallic-square with U-shaped slot

Enhancing MIMO Antenna Isolation with Novel Electromagnetic Band Gap (EBG) Structure and Genetic Algorithm Optimization

ABSTRACT A novel Electromagnetic Band Gap (EBG) structure is proposed to minimize common connector between closely spaced rectangular patch antennas. The 2D EBG architecture is placed on the horizontal plane of a 1/2 rectangle patch antenna array, reducing mutual coupling by over 20 dB without compromising far-field performance, gain, or bandwidth. By optimizing the EBG structure using a genetic algorithm, noise is reduced by −60 dB compared to −25 dB without it, improving the isolation of the antenna array. Inserting 3 EBG modules between the two patches decreases the 2.45 GHz mutual coupling to −60 dB, showcasing the significant enhancement in isolation. This MIMO antenna design with an EBG structure is suitable for wireless LAN communication systems, offering improved signal separation and performance. The proposed method integrates square patch antennas operating at 24 GHz with a metamaterial EBG structure on a Rogers R04350B substrate, using a genetic algorithm for optimization. Experimental results demonstrate over 22 dB improvement in isolation between antenna elements, maintaining consistent radiation patterns across frequencies.

Research Progress of Underwater Sound-absorbing Material

This article provides an overview of underwater sound-absorbing materials mainly applied with polyurethane matrix. It mainly elaborates on the underwater sound mechanism, commonly used underwater sound-absorbing materials and structures, as well as new underwater sound-absorbing material structures derived from local resonance phononic crystals, such as phononic crystals, local resonance phonon wood piles, and metamaterial sound-absorbing structures. This provides a broader development space and direction for the future development of underwater sound-absorbing materials

Introducing ANN-GP algorithm to estimate transient bending of the functionally graded graphene origami-enabled auxetic metamaterial structures

This article presents a new method called the artificial neural networks-genetic programming (ANNs-GP) algorithm, which effectively predicts the bending behavior of functionally graded graphene origami-enabled auxetic metamaterial (FG-GORAM) structures under transient conditions. Functionally graded materials (FGMs) display spatial heterogeneity in their composition and microstructure, resulting in distinctive mechanical characteristics that make them well-suited for a wide range of engineering applications. The objective of this study is to create a prediction model that can accurately capture the intricate transient bending behavior of FGM structures. To do this, the researchers have used the ANN-GP technique, which combines ANNs with GP. The ANN component acquires knowledge from a dataset including actual or simulated bending data, while the GP component fine-tunes the structure and parameters of the neural network to improve its ability to make accurate predictions. The proposed algorithm combines the strengths of ANNs and GP to accurately predict the bending behavior of FG-GORAM structures. This algorithm is robust and efficient, allowing designers and engineers to optimize the performance and reliability of these structures in various applications. The effectiveness of the ANN-GP method is proved by comparing it to experimental or simulated data. This shows that the algorithm has the potential to be a useful tool for designing and analyzing sophisticated materials and structures.

Functionally varied negative-stiffness metamaterial core sandwich structures with three-phase bending deformation

Abstract This paper introduces a novel class of negative-stiffness (NS) core sandwich composite structures that exhibit unique mechanical performance, including shape recovery, superelasticity, and energy absorption (EA) in bending and shear mode. The core of these structures consists of a periodic cellular arrangement of double-curved beams that undergo consecutive local snap-buckling transitions between multiple equilibrium states, enabling the structures to change shape reversibly between their initial and deformed configurations. To characterize the force-displacement relationship of the core, a comprehensive analysis was conducted using a combination of 3D printed models and finite-element simulations. The metamaterial core with gradient-thickness negative-stiffness beams were examined under uniform compression, demonstrating that the snap-through behavior of the curved beams was intricately controlled by the beam thickness in each row. The numerical simulations accurately predicted the deformation characteristics of the graded cellular core, supporting the design of a metamaterial core with functionally varied beam thickness for nonuniform transverse loading. This led to spatially controlled NS core material with specific EA of around 50 J kg−1 and an apparent core shear strength of 0.1 MPa, all mainly within the reusable elastic regime. The resulting sandwich structures efficiently mitigated the localized effect from concentrated compressive forces and achieved complete snap-through buckling in all curve beams. Three-point bending response revealed three distinct phases of flexural deformation: the local facial bending phase, the sequential core-snapping superelastic phase, and the global bending phase.

Study on the Equivalent Stiffness of a Local Resonance Metamaterial Concrete Unit Cell

This paper addresses the pressing scientific problem of accurately predicting the equivalent stiffness of local resonance metamaterial concrete unit cells. Existing theoretical models often fail to capture the nuanced dynamics of these complex systems, resulting in suboptimal predictions and hindering advancements in engineering applications. To address this deficit, this paper proposes a novel two-dimensional theoretical vibration model that incorporates shear stiffness, a crucial yet often overlooked parameter in previous formulations. Motivated by the need for improved predictive accuracy, this paper rigorously validates a new theoretical model through numerical simulations, considering variations in material parameters and geometric dimensions. The analysis reveals several key findings: firstly, the equivalent stiffness increases with elastic modulus while the error rate decreases, holding geometric parameters and Poisson’s ratio constant. Secondly, under fixed geometric parameters and coating elastic modulus, the equivalent stiffness rises with an increasing Poisson’s ratio, accompanied by a decrease in error rate. Importantly, this paper demonstrates that the proposed model exhibits the lowest error rate across all parameter conditions, facilitating superior prediction of equivalent stiffness. This advancement holds significant implications for the design and optimization of metamaterial structures in various engineering applications for vibration isolation, with promising enhancements of performance and efficiency.

Wireless power transfer efficiency enhancement based on a negative permeability double‐helix metamaterial structure

SummaryIn wireless power transfer (WPT) systems, extended transmission distances significantly impede efficiency, posing a major challenge to their practical application. This paper presents a novel ortho‐octagonal double‐helix metamaterial that can effectively enhance the transmission efficiency of WPT systems. It has theoretically derived and experimentally verified the enhancement of evanescent wave transmission by this metamaterial dielectric plate. A WPT simulation system operating at 10.78 MHz is constructed by HFSS software, and the effects of adding passive relay coils and different shapes of metamaterials on the transmission efficiency are comparatively investigated. Simulated data converge to indicate that integrating variously shaped metamaterials at the transceiver's end distinctly elevates the WPT system's transmission efficiency. When the transceiver coil spacing of the WPT system is greater than 22 cm, the effect of metamaterials on the system transmission efficiency enhancement shows an increasing and then decreasing trend as the distance increases. The positive octagonal metamaterial improves 12% over the circular metamaterial in the mid‐range transmission distance due to its better magnetic coupling effect. When the transceiver coil spacing is 22 cm, the open‐circuit voltage of the receiving coil after loading the metamaterial is stabilized to be enhanced by nearly five times, and it has the best effect at 30 cm, and the transmission efficiency is enhanced from 30% to 60%, which verifies the effective enhancement of the metamaterial on the transmission efficiency of the WPT system.

Electromagnetic wave absorption of polymer derived ceramic composites tuned by multi-component oxide solid solution

Polymer-derived ceramics (PDCs) are important ceramics for high temperature electromagnetic wave (EMW) absorption because of their tunable conductivity with the pyrolysis temperature. However, it is usually difficult to tune the dielectric properties of the PDCs by only controlling the content of absorption phase in the material system for the purpose of acquiring a wide EMW absorption band. In this work, we illustrate that the PDCs with wide-band high temperature absorption can be obtained through the synergistical tuning by multi-component oxide solid solution (MOS), nano ZrB2 and the metamaterial structure design. The PDCs were prepared by co-pyrolyzing the SiOC precursor, nano ZrB2 and MOS. The MOS helps to tune the permittivity of the PDCs without decreasing the conduction loss of the composites. The effective absorption band (lower than −10dB) of the metamaterial structure made by the prepared ceramic composites exceeds 12 GHz at the frequency range of 2–18 GHz from room temperature (RT) to 1000 °C, revealing a stable high temperature EMW absorption. The metamaterial structure shows good absorption in low frequency range at high temperatures, almost covering the entire S band from RT to 700 °C. The average EM absorption of the ceramic composites is lower than −15dB in the range of 2–18 GHz from RT to 1000 °C. The lowest reflection loss (RL) of the metamaterial is −45dB at 1000 °C. This study successfully address the challenge of simultaneously keeping impedance matching and retaining the strong attenuation of ceramic composites, greatly widening the high temperature EMW absorption band of PDC composites.

A four-band coherent perfect absorber of borophene metamaterial operating in the communication band

We propose a coherent perfect absorber based on a borophene metamaterial grating structure. Based on the theoretical analysis of the temporal coupled mode theory and the numerical results of the finite-difference time-domain simulations, the transmission characteristics of the system are investigated. The dynamic tunability of the absorption intensity and resonance wavelength is realized by adjusting the phase difference of the coherent incident beams and carrier density of borophene. Moreover, by optimizing the parameters, the coherent perfect absorption peak (99.99%) is obtained near the wavelength of 1550 nm, that is, the third communication window. Meanwhile, the structure can be operated in ultra-thin gratings as low as 6 nm and angle tolerances as large as 45°, which provides the possibility for applications in highly integrated and wide-angle tolerated devices.

Aluminum Nitride Thin Film Pyroelectric Detector Based on Metamaterial Absorber

Highly integrated pyroelectric detectors have been widely used in infrared spectrometers and gas detection. Aluminum nitride(AlN) has excellent compatibility with CMOS processes and is often used to fabricate piezoelectric and optoelectronic devices with superior performance. This study proposes a pyroelectric detector with AlN thin film as the sensitive element and integrated metamaterial absorber. Magnetron sputtering technology was used to prepare the AlN thin film as the sensitive element. To achieve narrowband specific absorption subsequently, a three-layer metamaterial absorber structure was designed and simulated. Preliminary processing of AlN pyroelectric detectors was performed based on MEMS technology. The designed narrowband absorbing structure exhibits near unity specific absorption, with a quality factor of 17.75. This study preliminarily verifies the application potential of AlN thin films in mid-infrared pyroelectric sensors, and realizes narrowband absorption through metamaterial structures, laying the foundation for the development of mid-infrared gas detection sensors.

Controlled circular dichroism with graphene-based metamaterial for terahertz wave

This article explores the design and analysis of a metal-graphene hybrid metamaterial structure tailored for tunable circular dichroism (CD) effects in the terahertz (THz) frequency regime. Chiral metamaterials have garnered considerable interest in photonics due to their versatile applications, including sensing, polarization manipulation, and chiral imaging. The proposed metamaterial unit cell features four meta-atoms with C4 rotational symmetry, composed of gold on a polyimide substrate. By strategically integrating the graphene sheets above the gold patterns, selective control over the absorption efficiency for the incident wave of left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) light is achieved. The study demonstrates that adjusting graphene chemical potential enables precise modulation of CD from 0.80 to 0.10 across a wide THz frequency spectrum. Furthermore, the article investigates the structure optical response for incident angles ranging up to 75°, revealing stable CD behavior up to 30° and intriguing dual-band effects beyond 50°. These findings underscore the potential of the proposed metamaterial for practical applications in photonics, sensing, and chiral imaging, offering tunable control over the CD effects in the THz regime.