Metamaterials programmed with target rate-dependent mechanical properties are efficient platforms for realizing advanced functionalities.Yet,the loading rate-dependent mechanical property programming has received limi...Metamaterials programmed with target rate-dependent mechanical properties are efficient platforms for realizing advanced functionalities.Yet,the loading rate-dependent mechanical property programming has received limited attention.Here,the“stair-building”strategy is employed in the rate domain by combining the bistability with viscoelasticity.An arbitrary target curve in the programmable space can be approximated by a“stair”built by two kinds of“bricks”.The“bricks”can be realized by a dual-bistable unit,constructed by two bistable structures in series.The dual-bistable unit can switch between two efficient stable phases without inducing changes in the global morphology.Such a unit exhibits N-shaped stress-strain curves at both efficient stable phases with different peak values,resulting in different heights of“bricks”.Moreover,the N-shaped curves have rate-dependent peak values,indicating that the heights of“bricks”change with loading rate.The“stair-building”strategy is realized by array-structured mechanical metamaterials based on dual-bistable units.Different stress-strain curves under various loading rates can be reprogrammed in the same piece of metamaterial by intentionally selecting the efficient stable phases of units.Besides,the rate effect of the metamaterial can also be tuned by reprogramming stress-strain curves under both low and high loading rates,respectively.This reprogrammable metamaterial is promising in smart vibration isolators and adaptive energy absorbers.展开更多
Metamaterials have exotic physical properties that rely on the construction of their underlying architecture.However,the physical properties of conventional mechanical metamaterials are permanently programmed into the...Metamaterials have exotic physical properties that rely on the construction of their underlying architecture.However,the physical properties of conventional mechanical metamaterials are permanently programmed into their periodic interconnect configurations,resulting in their lack of modularity,scalable fabrication,and programmability.Mechanical metamaterials typically exhibit a single extraordinary mechanical property or multiple extraordinary properties coupled together,making it difficult to realize multiple independent extraordinary mechanical properties.Here,the pixel mechanics metamaterials(PMMs)with multifunctional and reprogrammable properties are developed by arraying uncoupled constrained individual modular mechanics pixels(MPs).The MPs enable controlled conversion between two extraordinary mechanical properties(multistability and compression-torsion coupling deformation).Each MP exhibits 32 independent and reversible room temperature programming configurations.In addition,the programmability of metamaterials is further enhanced by shape memory polymer(SMP)and 4D printing,greatly enriching the design freedom.For the PMM consisting of m×n MPs,it has 32(m×n)independent room temperature programming configurations.The application prospects of metamaterials in the vibration isolation device and energy absorption device with programmable performance have been demonstrated.The vibration isolation frequencies of the MP before and after programming were[0 Hz-5.86 Hz],[0 Hz-13.67 Hz and 306.64 Hz-365.23 Hz].The total energy absorption of the developed PMM can be adjusted controllably in the range of 1.01 J-3.91 J.Six standard digital logic gates that do not require sustained external force are designed by controlling the closure between the modules.This design paradigm will facilitate the further development of multifunctional and reprogrammable metamaterials.展开更多
In this paper,a tunable metamaterial absorber based on a Dirac semimetal is proposed.It consists of three different structures,from top to bottom,namely a double semicircular Dirac semimetal resonator,a silicon dioxid...In this paper,a tunable metamaterial absorber based on a Dirac semimetal is proposed.It consists of three different structures,from top to bottom,namely a double semicircular Dirac semimetal resonator,a silicon dioxide substrate and a continuous vanadium dioxide(VO_(2))reflector layer.When the Fermi energy level of the Dirac semimetal is 10 meV,the absorber absorbs more than 90%in the 39.06-84.76 THz range.Firstly,taking advantage of the tunability of the conductivity of the Dirac semimetal,dynamic tuning of the absorption frequency can be achieved by changing the Fermi energy level of the Dirac semimetal without the need to optimise the geometry and remanufacture the structure.Secondly,the structure has been improved by the addition of the phase change material VO_(2),resulting in a much higher absorption performance of the absorber.Since VO_(2)is a temperature-sensitive metal oxide with an insulating phase below the phase transition temperature(about 68℃)and a metallic phase above the phase transition temperature,this paper also analyses the effect of VO_(2)on the absorptive performance at different temperatures,with the aim of further improving absorber performance.展开更多
Composed of natural materials but constructed using artificial structures through ingenious design,metamaterials possess properties beyond nature.Unlike traditional materials studies,metamaterials research requires gr...Composed of natural materials but constructed using artificial structures through ingenious design,metamaterials possess properties beyond nature.Unlike traditional materials studies,metamaterials research requires great human creativity in order to realize the desired properties and thereby the required functionalities through design.Such properties and functionalities are not necessarily available in nature,and their design can break through the existing materials ideology.This paper reviews progress in metamaterials research over the past 20 years in terms of the materials innovations that have achieved the designation of “meta.” In particular,we discuss future trends in metamaterials in the fields of both fundamental science and engineering.展开更多
Electromagnetic devices have been widely used in the fields of information communication,medical treatment,electrical engineering,and national defense,and their properties are strongly dependent on the constituent ele...Electromagnetic devices have been widely used in the fields of information communication,medical treatment,electrical engineering,and national defense,and their properties are strongly dependent on the constituent electromagnetic materials.Conversely,electromagnetic metamaterials(EMMs),which are artificially engineered with distinctive electromagnetic properties,can overcome the limitations of natural materials owing to their structural advantages.Three-dimensional(3D)printing is the most effec-tive technique for fabricating EMM devices with different geometric parameters and associated proper-ties.However,conventional 3D-printed EMM devices may lack manufacturing flexibility and environmental adaptability to different physical stimuli,such as electric and magnetic fields.Four-dimensional(4D)printing is an ideal technique for schemes to integrate structural design with intelligent materials environmentally adaptive to external fields,for example,the printed components can change shape under electric stimulation.Given the rapid advancements in the EMM field,this paper first reviews typical EMM devices,their design theories,and underlying principles.Subsequently,it presents various EMM structural topologies and manufacturing technologies,emphasizing the feasibility of combining 3D and 4D printing.In addition,we highlight the important applications of EMMs and their future trends and the challenges associated with functional EMMs and additive manufacturing.展开更多
SiC is a wave-absorbing material with good dielectric properties,high-temperature resistance,and corrosion resistance,which has great potential for development in the field of high-temperature wave-absorbing.However,S...SiC is a wave-absorbing material with good dielectric properties,high-temperature resistance,and corrosion resistance,which has great potential for development in the field of high-temperature wave-absorbing.However,SiC is limited by its low impedance-matching performance and single wave-absorbing mechanism.Therefore,compatible metamaterial technologies are required to enhance its wave-absorbing performance further.The electromagnetic wave(EMW)absorbing metamaterials can realize perfect absorption of EMWs in specific frequency bands and precise regulation of EMW phase,propagation mode,and absorption frequency bands through structural changes.However,the traditional molding methods for manufacturing complex geometric shapes require expensive molds,involve process complexity,and have poor molding accuracy and other limitations.Therefore,additive manufacturing(AM)technology,through material layered stacking to achieve the processing of materials,is a comprehensive multidisciplinary advanced manufacturing technology and has become the core technology for manufacturing metamaterials.This review introduces the principles and applications of different AM technologies for SiC and related materials,discusses the current status and development trends of various AM technologies for fabricating silicon-carbon-based wave-absorbing metamaterials,summarizes the limitations and technological shortcomings of existing AM technologies for fabricating silicon-carbon-based wave-absorbing metamaterials,and provides an outlook for the future development of related AM technologies.展开更多
Quasi-zero-stiffness(QZS)metamaterials have attracted significant interest for application in low-frequency vibration isolation.However,previous work has been limited by the design mechanism of QZS metamaterials,as it...Quasi-zero-stiffness(QZS)metamaterials have attracted significant interest for application in low-frequency vibration isolation.However,previous work has been limited by the design mechanism of QZS metamaterials,as it is still difficult to achieve a simplified structure suitable for practical engineering applications.Here,we introduce a class of programmable QZS metamaterials and a novel design mechanism that address this long-standing difficulty.The proposed QZS metamaterials are formed by an array of representative unit cells(RUCs)with the expected QZS features,where the QZS features of the RUC are tailored by means of a structural bionic mechanism.In our experiments,we validate the QZS features exhibited by the RUCs,the programmable QZS behavior,and the potential promising applications of these programmable QZS metamaterials in low-frequency vibration isolation.The obtained results could inspire a new class of programmable QZS metamaterials for low-frequency vibration isolation in current and future mechanical and other engineering applications.展开更多
In this review,we propose a comprehensive overview of additive manufacturing(AM)technologies and design possibilities in manufacturing metamaterials for various applications in the biomedical field,of which many are i...In this review,we propose a comprehensive overview of additive manufacturing(AM)technologies and design possibilities in manufacturing metamaterials for various applications in the biomedical field,of which many are inspired by nature itself.It describes how new AM technologies(e.g.continuous liquid interface production and multiphoton polymerization,etc)and recent developments in more mature AM technologies(e.g.powder bed fusion,stereolithography,and extrusion-based bioprinting(EBB),etc)lead to more precise,efficient,and personalized biomedical components.EBB is a revolutionary topic creating intricate models with remarkable mechanical compatibility of metamaterials,for instance,stress elimination for tissue engineering and regenerative medicine,negative or zero Poisson’s ratio.By exploiting the designs of porous structures(e.g.truss,triply periodic minimal surface,plant/animal-inspired,and functionally graded lattices,etc),AM-made bioactive bone implants,artificial tissues,and organs are made for tissue replacement.The material palette of the AM metamaterials has high diversity nowadays,ranging from alloys and metals(e.g.cobalt-chromium alloys and titanium,etc)to polymers(e.g.biodegradable polycaprolactone and polymethyl methacrylate,etc),which could be even integrated within bioactive ceramics.These advancements are driving the progress of the biomedical field,improving human health and quality of life.展开更多
1.Introduction To design novel architectures with unique properties that surpass those of natural matter,scientists have developed diverse structures/materials by incorporating artificial structures of periodic/aperio...1.Introduction To design novel architectures with unique properties that surpass those of natural matter,scientists have developed diverse structures/materials by incorporating artificial structures of periodic/aperiodic nano-,micro-,and macro-scale,so called metamaterials.展开更多
Acoustic metamaterials are artificially designed structures that demonstrate extraordinary capabilities in manipulating wave propagation by exploiting geometry-driven physical phenomena that transcend the limitations ...Acoustic metamaterials are artificially designed structures that demonstrate extraordinary capabilities in manipulating wave propagation by exploiting geometry-driven physical phenomena that transcend the limitations of traditional materials.Their complex architectures facilitate advanced functions such as sound absorption,vibration reduction,and directional wave control,making them highly applicable in sectors such as aerospace,automotive,and construction engineering.In this study,the dynamic acoustic responses of four different metamaterial configurations with geometric designs-honeycomb,gyroid,lattice,and cylindrical resonator-were numerically investigated using four base materials:aluminum,epoxy resin,steel,and carbon fiber reinforced polymer(CFRP).Frequency domain simulations were performed using COMSOL Multiphysics®to evaluate fundamental acoustic performance indicators,including transmission loss,phase velocity,acoustic impedance,and resonance characteristics.The findings indicate that geometry has a dominant effect on acoustic behavior,while material parameters such as density and stiffness play important roles in managing phase response and frequency-dependent sensitivity.Interestingly,despite differences in materials and structural configurations,the general patterns of transmission loss and phase velocity have shown consistent trends in most cases;this implies that geometric distribution and boundary constraints largely determine wave propagation phenomena.This integrative numerical framework provides valuable guidance for the rational design and optimization of next-generation acoustic metamaterials through strategic material-geometry coupling.展开更多
The ancient arts of paper folding and cutting-origami and kirigami-have long captivated both artists and engineers.Today,these techniques are inspiring the creation of adaptive structures and innovative metamaterials ...The ancient arts of paper folding and cutting-origami and kirigami-have long captivated both artists and engineers.Today,these techniques are inspiring the creation of adaptive structures and innovative metamaterials that challenge conventional mechanical paradigms.Whereas early research in origami/kirigami primarily addressed design principles and folding kinematics to achieve vast shape transformations,breakthroughs since the 2010s have unlocked new avenues in folding-and cutting-induced mechanics.By harnessing folding-induced deformations and leveraging strong geometric nonlinearities,researchers now realize exceptional mechanical properties such as auxetic behavior,high reconfigurability,programmable stiffness,impact absorption,and bistability or multi-stability.展开更多
Advanced programmable metamaterials with heterogeneous microstructures have become increasingly prevalent in scientific and engineering disciplines attributed to their tunable properties.However,exploring the structur...Advanced programmable metamaterials with heterogeneous microstructures have become increasingly prevalent in scientific and engineering disciplines attributed to their tunable properties.However,exploring the structure-property relationship in these materials,including forward prediction and inverse design,presents substantial challenges.The inhomogeneous microstructures significantly complicate traditional analytical or simulation-based approaches.Here,we establish a novel framework that integrates the machine learning(ML)-encoded multiscale computational method for forward prediction and Bayesian optimization for inverse design.Unlike prior end-to-end ML methods limited to specific problems,our framework is both load-independent and geometry-independent.This means that a single training session for a constitutive model suffices to tackle various problems directly,eliminating the need for repeated data collection or training.We demonstrate the efficacy and efficiency of this framework using metamaterials with designable elliptical holes or lattice honeycombs microstructures.Leveraging accelerated forward prediction,we can precisely customize the stiffness and shape of metamaterials under diverse loading scenarios,and extend this capability to multi-objective customization seamlessly.Moreover,we achieve topology optimization for stress alleviation at the crack tip,resulting in a significant reduction of Mises stress by up to 41.2%and yielding a theoretical interpretable pattern.This framework offers a general,efficient and precise tool for analyzing the structure-property relationships of novel metamaterials.展开更多
The nonlinear post-buckling response of functionally graded(FG)copper matrix plates enforced by graphene origami auxetic metamaterials(GOAMs)is investigated in the currentwork.The auxeticmaterial properties of the pla...The nonlinear post-buckling response of functionally graded(FG)copper matrix plates enforced by graphene origami auxetic metamaterials(GOAMs)is investigated in the currentwork.The auxeticmaterial properties of the plate are controlled by graphene content and the degree of origami folding,which are graded across the thickness of the plate.Thematerial properties of the GOAM plate are evaluated using genetic micro-mechanicalmodels.Governing nonlinear eigenvalue problems for the post-buckling response of the GOAM composite plate are derived using the virtual work principle and a four-variable nonlinear shear deformation theory.A novel differential quadrature method(DQM)algorithm is developed to solve the nonlinear eigenvalue problem.Detailed parametric studies are presented to explore the effects of graphene content,folding degree,and GO distribution patterns on the post-buckling responses of GOAM plates.Results show that high tunability in post-buckling characteristics can be achieved by using GOAM.FunctionallyGradedGraphene OrigamiAuxeticMetamaterials(FG-GOAM)plates can be used in aerospace structures to improve their structural performance and response.展开更多
Mechanical metamaterials are artificial materials that control their macroscopic properties using repetitive units rather than chemical constituents.Through rational design and spatial arrangement of the unit cells,me...Mechanical metamaterials are artificial materials that control their macroscopic properties using repetitive units rather than chemical constituents.Through rational design and spatial arrangement of the unit cells,mechanical metamaterials can realize a range of counterintuitive properties on a larger scale.In this work,a type of mechanical metamaterial unit cell is proposed,exhibiting both compression-twist coupling behavior and bistability that can be programmed.The design involves linking two cylindrical frames with topology-designed inclined beams.Under uniaxial loading,the structure undergoes a compression-twist deformation,along with buckling at two joints of the inclined beams.Through a rational design of the unit's geometric parameters,the structure can retain its deformed state once the applied displacement surpasses a specified threshold,showing a programmed bistable characteristic.We investigated the influence of the involved parameters on the mechanical response of the unit cells numerically,which agrees well with our experimental results.Since the inclined beams dominate the elastic deformation of unit cells,the two cylindrical frames are almost independent of the bistable response and can therefore be designed in any shape for various arrangements of unit cells in multi-dimensional space.展开更多
Controlling low-frequency noise presents a significant challenge for traditional sound absorption materials,such as foams and fibrous substances.Recently developed acoustic absorption metamaterials,which rely on local...Controlling low-frequency noise presents a significant challenge for traditional sound absorption materials,such as foams and fibrous substances.Recently developed acoustic absorption metamaterials,which rely on local resonance can effectively balance the volume occupation and low-frequency absorption performance.However,these materials often exhibit a very narrow and fixed absorption band.Inspired by Helmholtz resonators and bistable structures,we propose bistable reconfigurable acoustic metamaterials(BRAMs)that offer multiband low-frequency absorption.These BRAMs are fabricated using shape-memory polylactic acid(SM-PLA)via four-dimension(4D)printing technology.Consequently,the geometry and absorption performance of the BRAMs can be adjusted by applying thermal stimuli(at 55℃)to switch between two stable states.The BRAMs demonstrate excellent low-frequency absorption with multiband characteristics,achieving an absorption coefficient of 0.981 at 136 Hz and 0.998 at 230 Hz for stable state I,and coefficients of 0.984 at 156 Hz and 0.961 at 542 Hz for stable state II.It was found that the BRAMs with different inclined plate angles had linear recovery stages,and the recovery speeds range from 0.75 mm/s to 1.1 mm/s.By combining a rational structural design and 4D printing,the reported reconfigurable acoustic metamaterials will inspire further studies on the design of dynamic and broadband absorption devices.展开更多
Open thin-shell structures exhibit advantages such as lightweight properties and high energy absorption efficiency. By randomly stacking these structures as unit cells, adjustable mechanical metamaterials with tunable...Open thin-shell structures exhibit advantages such as lightweight properties and high energy absorption efficiency. By randomly stacking these structures as unit cells, adjustable mechanical metamaterials with tunable and stable mechanical properties can be constructed. This study investigates the mechanical performance of randomly stacked open thin-shell mechanical metamaterials using a combined experimental and numerical simulation approach. Results indicate that under compressive loading, shell unit cells primarily dissipate energy through large deformation, snap-fit behavior, friction, and shell relocation. Different combinations of randomly stacked mechanical metamaterials demonstrate nearly identical energy dissipation ratios during the first compressionunloading cycle, indicating that the energy dissipation efficiency exhibits robust stability independent of contact and geometric randomness. However, under limit cycle conditions, increasing the proportion of Type Ⅱ shells enhances the maximum relative displacement, energy dissipation capacity, and energy dissipation ratio by up to fivefold. Notably, under compressive loading, Type Ⅰ shells engaged through snap-fit behavior exhibit irreversible deformation after unloading, while Type Ⅱ shells maintain their configuration without active engagement. The proportion of Type Ⅱ shells directly determines the mechanical performance of the structure.This research provides new references for the development of lightweight mechanical metamaterials, disordered mechanical metamaterials, and adjustable mechanical metamaterials.展开更多
Reconfigurable metamaterials significantly expand the application scenarios and operating frequency range of metamaterials,making them promising candidates for use in smart tunable device.Here,we propose and experimen...Reconfigurable metamaterials significantly expand the application scenarios and operating frequency range of metamaterials,making them promising candidates for use in smart tunable device.Here,we propose and experimentally demonstrate that integrating metamaterial design principles with the intrinsic features of natural materials can engineer thermal smart metadevices.Tunable extraordinary optical transmission like(EOT-like)phenomena have been achieved in the microwave regime using shape memory alloy(SMA).The strongly localized fields generated by designed metadevices,combined with the intense interference of incident waves,enhance transmission through subwavelength apertures.Leveraging the temperature-responsive properties of SMA,the morphology of the metadevice can be recontructed,thereby modifying its response to electromagnetic waves.The experiments demonstrated control over the operating frequency and transmission amplitude of EOT-like behavior,achieving a maximum transmission enhancement factor of 126.Furthermore,the metadevices with modular design enable the realization of multiple functions with independent control have been demonstrated.The proposed SMA-based metamaterials offer advantages in terms of miniaturization,easy processing,and high design flexibility.They may have potential applications in microwave devices requiring temperature control,such as sensing and monitoring.展开更多
Traditional space-coiled acoustic metamaterials have been widely used in the fields of low-frequency sound absorption and noise reduction.However,they have limitations in terms of low-frequency absorption bandwidth,an...Traditional space-coiled acoustic metamaterials have been widely used in the fields of low-frequency sound absorption and noise reduction.However,they have limitations in terms of low-frequency absorption bandwidth,and the weak coupling effect under complex coiled structures also limits their applications.In this work,we introduce the composite structure changing the characteristic impedance of acoustic metamaterials to enhance the coupling effect.Meanwhile,the perforated plates with inclined design instead of traditional partitions greatly improve the sound absorption.The model and method designed in this paper show significant innovation in enhancing low-frequency absorption performance.展开更多
Liquid crystal elastomers(LCEs)are advanced materials characterized by their rubber-like hyperelasticity and liquid crystal phase transitions,offering exceptional mechanical properties.The development of smart mechani...Liquid crystal elastomers(LCEs)are advanced materials characterized by their rubber-like hyperelasticity and liquid crystal phase transitions,offering exceptional mechanical properties.The development of smart mechanical metamaterials(SMMs)from LCEs expands the potential for controlling mechanical responses and achieving nonlinear behaviors not possible with traditional metamaterials.However,the challenge lies in managing the interplay between nonlinear material responses and structural complexity,making the inverse design of LCE-based SMMs exceptionally demanding.In this paper,we introduce a design framework for LCE smart mechanical metamaterials that leverages neural networks and evolution strategies(ES)to optimize designs with nonlinear mechanical responses.Our approach involves constructing a flexible,unit-cell-based metamaterial model that integrates the soft elastic behavior and thermo-mechanical coupling of LCEs.The combination of microscopic liquid crystal molecule rotation and macroscopic block rotation enables highly tunable and nonlinear mechanical behaviors,of which the precise inverse design of stress-stretch responses is obtained via neural networks combined with ES.In addition,stimuli responses in the liquid crystal elastomers enable real-time adaptability and achieve tailored stress plateaus that are not possible with traditional metamaterials.Our findings provide new pathways in the design and optimization of advanced materials in flexible electronic devices,intelligent actuators,and systems for energy absorption and dissipation.展开更多
Metamaterials,owing to their exceptional physical characteristics that are absent in natural materials,have emerged as a crucial constituent of intelligent devices and systems.However,there are still significant chall...Metamaterials,owing to their exceptional physical characteristics that are absent in natural materials,have emerged as a crucial constituent of intelligent devices and systems.However,there are still significant challenges that necessitate immediate attention,as they have considerably constrained the applicability of metamaterials,including fixed mechanical properties post-fabrication and restricted design freedom.Here,thermo-responsive,photo-responsive,electro-responsive,and magneto-responsive shape memory polymer nano-composites were developed,and shape memory gradient metamaterials were fabricated using multi-material 4D printing technology.The correlation mechanism between the design parameters and the mechanical properties of multi-responsive gradient metamaterials was systematically analyzed,and the highly designable and programmable configuration and mechanical properties of the gradient metamaterials were realized.More importantly,4D printed multi-responsive shape memory polymer gradient metamaterials can be programmed in situ without additional infrastructure for multi-functional mechanical functions,paving the way for the realization of multiple functions of a single structure.Based on the multi-responsive gradient metamaterials,4D printed digital pixel metamaterial intelligent information carriers were fabricated,featuring customizable encryption and decryption protocols,exceptional scalability,and reusability.Additionally,4D printed gradient metamaterial logic gate electronic devices were developed,which were anticipated to contribute to the development of smart,adaptable robotic systems that combine sensing,actuation,and decision-making capabilities.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12225201,12372126,12002016,and 12172026)the National Key Research and Development Program of China(Grant No.2020YFB1313003)the Fundamental Research Funds for the Central Universities are gratefully acknowledged.
文摘Metamaterials programmed with target rate-dependent mechanical properties are efficient platforms for realizing advanced functionalities.Yet,the loading rate-dependent mechanical property programming has received limited attention.Here,the“stair-building”strategy is employed in the rate domain by combining the bistability with viscoelasticity.An arbitrary target curve in the programmable space can be approximated by a“stair”built by two kinds of“bricks”.The“bricks”can be realized by a dual-bistable unit,constructed by two bistable structures in series.The dual-bistable unit can switch between two efficient stable phases without inducing changes in the global morphology.Such a unit exhibits N-shaped stress-strain curves at both efficient stable phases with different peak values,resulting in different heights of“bricks”.Moreover,the N-shaped curves have rate-dependent peak values,indicating that the heights of“bricks”change with loading rate.The“stair-building”strategy is realized by array-structured mechanical metamaterials based on dual-bistable units.Different stress-strain curves under various loading rates can be reprogrammed in the same piece of metamaterial by intentionally selecting the efficient stable phases of units.Besides,the rate effect of the metamaterial can also be tuned by reprogramming stress-strain curves under both low and high loading rates,respectively.This reprogrammable metamaterial is promising in smart vibration isolators and adaptive energy absorbers.
基金the financial support provided by the National Key R&D Program of China(2022YFB3805700)the National Natural Science Foundation of China(Grant Nos.12072094 and 12172106)+2 种基金the China Postdoctoral Science Foundation(Grant No.2023M730869)the Heilongjiang Natural Science Foundation Joint Guidance Project(Grant No.LH2023A004)the Postdoctoral Fellowship Program of CPSF(Grant No.GZB20230959)。
文摘Metamaterials have exotic physical properties that rely on the construction of their underlying architecture.However,the physical properties of conventional mechanical metamaterials are permanently programmed into their periodic interconnect configurations,resulting in their lack of modularity,scalable fabrication,and programmability.Mechanical metamaterials typically exhibit a single extraordinary mechanical property or multiple extraordinary properties coupled together,making it difficult to realize multiple independent extraordinary mechanical properties.Here,the pixel mechanics metamaterials(PMMs)with multifunctional and reprogrammable properties are developed by arraying uncoupled constrained individual modular mechanics pixels(MPs).The MPs enable controlled conversion between two extraordinary mechanical properties(multistability and compression-torsion coupling deformation).Each MP exhibits 32 independent and reversible room temperature programming configurations.In addition,the programmability of metamaterials is further enhanced by shape memory polymer(SMP)and 4D printing,greatly enriching the design freedom.For the PMM consisting of m×n MPs,it has 32(m×n)independent room temperature programming configurations.The application prospects of metamaterials in the vibration isolation device and energy absorption device with programmable performance have been demonstrated.The vibration isolation frequencies of the MP before and after programming were[0 Hz-5.86 Hz],[0 Hz-13.67 Hz and 306.64 Hz-365.23 Hz].The total energy absorption of the developed PMM can be adjusted controllably in the range of 1.01 J-3.91 J.Six standard digital logic gates that do not require sustained external force are designed by controlling the closure between the modules.This design paradigm will facilitate the further development of multifunctional and reprogrammable metamaterials.
文摘In this paper,a tunable metamaterial absorber based on a Dirac semimetal is proposed.It consists of three different structures,from top to bottom,namely a double semicircular Dirac semimetal resonator,a silicon dioxide substrate and a continuous vanadium dioxide(VO_(2))reflector layer.When the Fermi energy level of the Dirac semimetal is 10 meV,the absorber absorbs more than 90%in the 39.06-84.76 THz range.Firstly,taking advantage of the tunability of the conductivity of the Dirac semimetal,dynamic tuning of the absorption frequency can be achieved by changing the Fermi energy level of the Dirac semimetal without the need to optimise the geometry and remanufacture the structure.Secondly,the structure has been improved by the addition of the phase change material VO_(2),resulting in a much higher absorption performance of the absorber.Since VO_(2)is a temperature-sensitive metal oxide with an insulating phase below the phase transition temperature(about 68℃)and a metallic phase above the phase transition temperature,this paper also analyses the effect of VO_(2)on the absorptive performance at different temperatures,with the aim of further improving absorber performance.
基金supported by the National Key Research and Development Program of China (2022YFB3806000)the Key Program of National Natural Science Foundation of China (52332006)。
文摘Composed of natural materials but constructed using artificial structures through ingenious design,metamaterials possess properties beyond nature.Unlike traditional materials studies,metamaterials research requires great human creativity in order to realize the desired properties and thereby the required functionalities through design.Such properties and functionalities are not necessarily available in nature,and their design can break through the existing materials ideology.This paper reviews progress in metamaterials research over the past 20 years in terms of the materials innovations that have achieved the designation of “meta.” In particular,we discuss future trends in metamaterials in the fields of both fundamental science and engineering.
基金sponsored by the National Natural Science Foundation of China(52275331 and 52205358)the National Key Research and Development Program of China(2023YFB4604800)+1 种基金the Key Research and Development Program of Hubei Province(2022BAA011)the Hong Kong Scholars Program(XJ2022014).
文摘Electromagnetic devices have been widely used in the fields of information communication,medical treatment,electrical engineering,and national defense,and their properties are strongly dependent on the constituent electromagnetic materials.Conversely,electromagnetic metamaterials(EMMs),which are artificially engineered with distinctive electromagnetic properties,can overcome the limitations of natural materials owing to their structural advantages.Three-dimensional(3D)printing is the most effec-tive technique for fabricating EMM devices with different geometric parameters and associated proper-ties.However,conventional 3D-printed EMM devices may lack manufacturing flexibility and environmental adaptability to different physical stimuli,such as electric and magnetic fields.Four-dimensional(4D)printing is an ideal technique for schemes to integrate structural design with intelligent materials environmentally adaptive to external fields,for example,the printed components can change shape under electric stimulation.Given the rapid advancements in the EMM field,this paper first reviews typical EMM devices,their design theories,and underlying principles.Subsequently,it presents various EMM structural topologies and manufacturing technologies,emphasizing the feasibility of combining 3D and 4D printing.In addition,we highlight the important applications of EMMs and their future trends and the challenges associated with functional EMMs and additive manufacturing.
基金supported by National Natural Science Foundation of China(Grant No.U2006218)Project of Construction and Support for High-Level Innovative Teams of Beijing Municipal Institutions(Grant No.BPHR20220124).
文摘SiC is a wave-absorbing material with good dielectric properties,high-temperature resistance,and corrosion resistance,which has great potential for development in the field of high-temperature wave-absorbing.However,SiC is limited by its low impedance-matching performance and single wave-absorbing mechanism.Therefore,compatible metamaterial technologies are required to enhance its wave-absorbing performance further.The electromagnetic wave(EMW)absorbing metamaterials can realize perfect absorption of EMWs in specific frequency bands and precise regulation of EMW phase,propagation mode,and absorption frequency bands through structural changes.However,the traditional molding methods for manufacturing complex geometric shapes require expensive molds,involve process complexity,and have poor molding accuracy and other limitations.Therefore,additive manufacturing(AM)technology,through material layered stacking to achieve the processing of materials,is a comprehensive multidisciplinary advanced manufacturing technology and has become the core technology for manufacturing metamaterials.This review introduces the principles and applications of different AM technologies for SiC and related materials,discusses the current status and development trends of various AM technologies for fabricating silicon-carbon-based wave-absorbing metamaterials,summarizes the limitations and technological shortcomings of existing AM technologies for fabricating silicon-carbon-based wave-absorbing metamaterials,and provides an outlook for the future development of related AM technologies.
基金supported by the National Natural Science Foundation of China(52332006)the National Key Research and Development Program of China(2022YFB380600 and 2023YFB3811401)+1 种基金the China Postdoctoral Science Foundation(2022M721850)Southwest United Graduate School Research Program(202302AO370008)。
文摘Quasi-zero-stiffness(QZS)metamaterials have attracted significant interest for application in low-frequency vibration isolation.However,previous work has been limited by the design mechanism of QZS metamaterials,as it is still difficult to achieve a simplified structure suitable for practical engineering applications.Here,we introduce a class of programmable QZS metamaterials and a novel design mechanism that address this long-standing difficulty.The proposed QZS metamaterials are formed by an array of representative unit cells(RUCs)with the expected QZS features,where the QZS features of the RUC are tailored by means of a structural bionic mechanism.In our experiments,we validate the QZS features exhibited by the RUCs,the programmable QZS behavior,and the potential promising applications of these programmable QZS metamaterials in low-frequency vibration isolation.The obtained results could inspire a new class of programmable QZS metamaterials for low-frequency vibration isolation in current and future mechanical and other engineering applications.
基金sponsored by the Science and Technology Program of Hubei Province,China(2022EHB020,2023BBB096)support provided by Centre of the Excellence in Production Research(XPRES)at KTH。
文摘In this review,we propose a comprehensive overview of additive manufacturing(AM)technologies and design possibilities in manufacturing metamaterials for various applications in the biomedical field,of which many are inspired by nature itself.It describes how new AM technologies(e.g.continuous liquid interface production and multiphoton polymerization,etc)and recent developments in more mature AM technologies(e.g.powder bed fusion,stereolithography,and extrusion-based bioprinting(EBB),etc)lead to more precise,efficient,and personalized biomedical components.EBB is a revolutionary topic creating intricate models with remarkable mechanical compatibility of metamaterials,for instance,stress elimination for tissue engineering and regenerative medicine,negative or zero Poisson’s ratio.By exploiting the designs of porous structures(e.g.truss,triply periodic minimal surface,plant/animal-inspired,and functionally graded lattices,etc),AM-made bioactive bone implants,artificial tissues,and organs are made for tissue replacement.The material palette of the AM metamaterials has high diversity nowadays,ranging from alloys and metals(e.g.cobalt-chromium alloys and titanium,etc)to polymers(e.g.biodegradable polycaprolactone and polymethyl methacrylate,etc),which could be even integrated within bioactive ceramics.These advancements are driving the progress of the biomedical field,improving human health and quality of life.
基金financially supported by the National Key Research and Development Program of China(2023YFB4604800)the National Natural Science Foundation of China(52275331)financial support from the Hong Kong Scholars Program(XJ2022014)。
文摘1.Introduction To design novel architectures with unique properties that surpass those of natural matter,scientists have developed diverse structures/materials by incorporating artificial structures of periodic/aperiodic nano-,micro-,and macro-scale,so called metamaterials.
文摘Acoustic metamaterials are artificially designed structures that demonstrate extraordinary capabilities in manipulating wave propagation by exploiting geometry-driven physical phenomena that transcend the limitations of traditional materials.Their complex architectures facilitate advanced functions such as sound absorption,vibration reduction,and directional wave control,making them highly applicable in sectors such as aerospace,automotive,and construction engineering.In this study,the dynamic acoustic responses of four different metamaterial configurations with geometric designs-honeycomb,gyroid,lattice,and cylindrical resonator-were numerically investigated using four base materials:aluminum,epoxy resin,steel,and carbon fiber reinforced polymer(CFRP).Frequency domain simulations were performed using COMSOL Multiphysics®to evaluate fundamental acoustic performance indicators,including transmission loss,phase velocity,acoustic impedance,and resonance characteristics.The findings indicate that geometry has a dominant effect on acoustic behavior,while material parameters such as density and stiffness play important roles in managing phase response and frequency-dependent sensitivity.Interestingly,despite differences in materials and structural configurations,the general patterns of transmission loss and phase velocity have shown consistent trends in most cases;this implies that geometric distribution and boundary constraints largely determine wave propagation phenomena.This integrative numerical framework provides valuable guidance for the rational design and optimization of next-generation acoustic metamaterials through strategic material-geometry coupling.
文摘The ancient arts of paper folding and cutting-origami and kirigami-have long captivated both artists and engineers.Today,these techniques are inspiring the creation of adaptive structures and innovative metamaterials that challenge conventional mechanical paradigms.Whereas early research in origami/kirigami primarily addressed design principles and folding kinematics to achieve vast shape transformations,breakthroughs since the 2010s have unlocked new avenues in folding-and cutting-induced mechanics.By harnessing folding-induced deformations and leveraging strong geometric nonlinearities,researchers now realize exceptional mechanical properties such as auxetic behavior,high reconfigurability,programmable stiffness,impact absorption,and bistability or multi-stability.
基金supported by the National Natural Science Foundation of China (Grant Nos.12102021,12372105,12172026,and 12225201)the Fundamental Research Funds for the Central Universities and the Academic Excellence Foundation of BUAA for PhD Students.
文摘Advanced programmable metamaterials with heterogeneous microstructures have become increasingly prevalent in scientific and engineering disciplines attributed to their tunable properties.However,exploring the structure-property relationship in these materials,including forward prediction and inverse design,presents substantial challenges.The inhomogeneous microstructures significantly complicate traditional analytical or simulation-based approaches.Here,we establish a novel framework that integrates the machine learning(ML)-encoded multiscale computational method for forward prediction and Bayesian optimization for inverse design.Unlike prior end-to-end ML methods limited to specific problems,our framework is both load-independent and geometry-independent.This means that a single training session for a constitutive model suffices to tackle various problems directly,eliminating the need for repeated data collection or training.We demonstrate the efficacy and efficiency of this framework using metamaterials with designable elliptical holes or lattice honeycombs microstructures.Leveraging accelerated forward prediction,we can precisely customize the stiffness and shape of metamaterials under diverse loading scenarios,and extend this capability to multi-objective customization seamlessly.Moreover,we achieve topology optimization for stress alleviation at the crack tip,resulting in a significant reduction of Mises stress by up to 41.2%and yielding a theoretical interpretable pattern.This framework offers a general,efficient and precise tool for analyzing the structure-property relationships of novel metamaterials.
文摘The nonlinear post-buckling response of functionally graded(FG)copper matrix plates enforced by graphene origami auxetic metamaterials(GOAMs)is investigated in the currentwork.The auxeticmaterial properties of the plate are controlled by graphene content and the degree of origami folding,which are graded across the thickness of the plate.Thematerial properties of the GOAM plate are evaluated using genetic micro-mechanicalmodels.Governing nonlinear eigenvalue problems for the post-buckling response of the GOAM composite plate are derived using the virtual work principle and a four-variable nonlinear shear deformation theory.A novel differential quadrature method(DQM)algorithm is developed to solve the nonlinear eigenvalue problem.Detailed parametric studies are presented to explore the effects of graphene content,folding degree,and GO distribution patterns on the post-buckling responses of GOAM plates.Results show that high tunability in post-buckling characteristics can be achieved by using GOAM.FunctionallyGradedGraphene OrigamiAuxeticMetamaterials(FG-GOAM)plates can be used in aerospace structures to improve their structural performance and response.
基金supported by the National Natural Science Foundation of China(Grant Numbers:12125205,12321002,12072316,12132014)the Zhejiang Provincial Natural Science Foundation of China(LD22A020001).
文摘Mechanical metamaterials are artificial materials that control their macroscopic properties using repetitive units rather than chemical constituents.Through rational design and spatial arrangement of the unit cells,mechanical metamaterials can realize a range of counterintuitive properties on a larger scale.In this work,a type of mechanical metamaterial unit cell is proposed,exhibiting both compression-twist coupling behavior and bistability that can be programmed.The design involves linking two cylindrical frames with topology-designed inclined beams.Under uniaxial loading,the structure undergoes a compression-twist deformation,along with buckling at two joints of the inclined beams.Through a rational design of the unit's geometric parameters,the structure can retain its deformed state once the applied displacement surpasses a specified threshold,showing a programmed bistable characteristic.We investigated the influence of the involved parameters on the mechanical response of the unit cells numerically,which agrees well with our experimental results.Since the inclined beams dominate the elastic deformation of unit cells,the two cylindrical frames are almost independent of the bistable response and can therefore be designed in any shape for various arrangements of unit cells in multi-dimensional space.
基金financially supported by National Key Research and Development Program of China(Grant No.2023YFB4604800)National Natural Science Foundation of China(Grant No.52275331)financial support from the Hong Kong Scholars Program(Grant No.XJ2022014).
文摘Controlling low-frequency noise presents a significant challenge for traditional sound absorption materials,such as foams and fibrous substances.Recently developed acoustic absorption metamaterials,which rely on local resonance can effectively balance the volume occupation and low-frequency absorption performance.However,these materials often exhibit a very narrow and fixed absorption band.Inspired by Helmholtz resonators and bistable structures,we propose bistable reconfigurable acoustic metamaterials(BRAMs)that offer multiband low-frequency absorption.These BRAMs are fabricated using shape-memory polylactic acid(SM-PLA)via four-dimension(4D)printing technology.Consequently,the geometry and absorption performance of the BRAMs can be adjusted by applying thermal stimuli(at 55℃)to switch between two stable states.The BRAMs demonstrate excellent low-frequency absorption with multiband characteristics,achieving an absorption coefficient of 0.981 at 136 Hz and 0.998 at 230 Hz for stable state I,and coefficients of 0.984 at 156 Hz and 0.961 at 542 Hz for stable state II.It was found that the BRAMs with different inclined plate angles had linear recovery stages,and the recovery speeds range from 0.75 mm/s to 1.1 mm/s.By combining a rational structural design and 4D printing,the reported reconfigurable acoustic metamaterials will inspire further studies on the design of dynamic and broadband absorption devices.
文摘Open thin-shell structures exhibit advantages such as lightweight properties and high energy absorption efficiency. By randomly stacking these structures as unit cells, adjustable mechanical metamaterials with tunable and stable mechanical properties can be constructed. This study investigates the mechanical performance of randomly stacked open thin-shell mechanical metamaterials using a combined experimental and numerical simulation approach. Results indicate that under compressive loading, shell unit cells primarily dissipate energy through large deformation, snap-fit behavior, friction, and shell relocation. Different combinations of randomly stacked mechanical metamaterials demonstrate nearly identical energy dissipation ratios during the first compressionunloading cycle, indicating that the energy dissipation efficiency exhibits robust stability independent of contact and geometric randomness. However, under limit cycle conditions, increasing the proportion of Type Ⅱ shells enhances the maximum relative displacement, energy dissipation capacity, and energy dissipation ratio by up to fivefold. Notably, under compressive loading, Type Ⅰ shells engaged through snap-fit behavior exhibit irreversible deformation after unloading, while Type Ⅱ shells maintain their configuration without active engagement. The proportion of Type Ⅱ shells directly determines the mechanical performance of the structure.This research provides new references for the development of lightweight mechanical metamaterials, disordered mechanical metamaterials, and adjustable mechanical metamaterials.
基金the financial support from the National Key R&D Program of China (Nos. 2023YFB3811400, 2022YFB3806000)the National Natural Science Foundation of China (Nos. 12074314, 52202370, 52332006)+3 种基金the Aeronautical Science Foundation of China (No. 20230018053007)the Science and Technology New Star Program of Shaanxi Province (No. 2023KJXX-148)the Fundamental Research Funds for the Central UniversitiesChina Postdoctoral Science Foundation (No. 2023T160359)
文摘Reconfigurable metamaterials significantly expand the application scenarios and operating frequency range of metamaterials,making them promising candidates for use in smart tunable device.Here,we propose and experimentally demonstrate that integrating metamaterial design principles with the intrinsic features of natural materials can engineer thermal smart metadevices.Tunable extraordinary optical transmission like(EOT-like)phenomena have been achieved in the microwave regime using shape memory alloy(SMA).The strongly localized fields generated by designed metadevices,combined with the intense interference of incident waves,enhance transmission through subwavelength apertures.Leveraging the temperature-responsive properties of SMA,the morphology of the metadevice can be recontructed,thereby modifying its response to electromagnetic waves.The experiments demonstrated control over the operating frequency and transmission amplitude of EOT-like behavior,achieving a maximum transmission enhancement factor of 126.Furthermore,the metadevices with modular design enable the realization of multiple functions with independent control have been demonstrated.The proposed SMA-based metamaterials offer advantages in terms of miniaturization,easy processing,and high design flexibility.They may have potential applications in microwave devices requiring temperature control,such as sensing and monitoring.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFB3204303)the National Natural Science Foundation of China(Grant No.11934009)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.020414380195)the Foundation of State Key Laboratory of Ultrasound in Medicine and Engineering(Grant No.2022KFKT021)。
文摘Traditional space-coiled acoustic metamaterials have been widely used in the fields of low-frequency sound absorption and noise reduction.However,they have limitations in terms of low-frequency absorption bandwidth,and the weak coupling effect under complex coiled structures also limits their applications.In this work,we introduce the composite structure changing the characteristic impedance of acoustic metamaterials to enhance the coupling effect.Meanwhile,the perforated plates with inclined design instead of traditional partitions greatly improve the sound absorption.The model and method designed in this paper show significant innovation in enhancing low-frequency absorption performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.12322207,12202120 and T2293720/T2293722)the Shenzhen Science and Technology Program,China(Grant No.JCYJ20220531095210022)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2022037)financial support by the National Key Research and Development Program of China(Grant No.2023YFB3812500)。
文摘Liquid crystal elastomers(LCEs)are advanced materials characterized by their rubber-like hyperelasticity and liquid crystal phase transitions,offering exceptional mechanical properties.The development of smart mechanical metamaterials(SMMs)from LCEs expands the potential for controlling mechanical responses and achieving nonlinear behaviors not possible with traditional metamaterials.However,the challenge lies in managing the interplay between nonlinear material responses and structural complexity,making the inverse design of LCE-based SMMs exceptionally demanding.In this paper,we introduce a design framework for LCE smart mechanical metamaterials that leverages neural networks and evolution strategies(ES)to optimize designs with nonlinear mechanical responses.Our approach involves constructing a flexible,unit-cell-based metamaterial model that integrates the soft elastic behavior and thermo-mechanical coupling of LCEs.The combination of microscopic liquid crystal molecule rotation and macroscopic block rotation enables highly tunable and nonlinear mechanical behaviors,of which the precise inverse design of stress-stretch responses is obtained via neural networks combined with ES.In addition,stimuli responses in the liquid crystal elastomers enable real-time adaptability and achieve tailored stress plateaus that are not possible with traditional metamaterials.Our findings provide new pathways in the design and optimization of advanced materials in flexible electronic devices,intelligent actuators,and systems for energy absorption and dissipation.
基金supported by the National Key R&D Program of China(2022YFB3805700)the National Natural Science Foundation of China(Grant No.12302198)+2 种基金China Postdoctoral Science Foundation(2022M720042)Heilongjiang Postdoctoral Science Foundation(LBH-Z22016)Key Project of Heilongjiang Provincial Department of Science and Technology(2022ZX02C25).
文摘Metamaterials,owing to their exceptional physical characteristics that are absent in natural materials,have emerged as a crucial constituent of intelligent devices and systems.However,there are still significant challenges that necessitate immediate attention,as they have considerably constrained the applicability of metamaterials,including fixed mechanical properties post-fabrication and restricted design freedom.Here,thermo-responsive,photo-responsive,electro-responsive,and magneto-responsive shape memory polymer nano-composites were developed,and shape memory gradient metamaterials were fabricated using multi-material 4D printing technology.The correlation mechanism between the design parameters and the mechanical properties of multi-responsive gradient metamaterials was systematically analyzed,and the highly designable and programmable configuration and mechanical properties of the gradient metamaterials were realized.More importantly,4D printed multi-responsive shape memory polymer gradient metamaterials can be programmed in situ without additional infrastructure for multi-functional mechanical functions,paving the way for the realization of multiple functions of a single structure.Based on the multi-responsive gradient metamaterials,4D printed digital pixel metamaterial intelligent information carriers were fabricated,featuring customizable encryption and decryption protocols,exceptional scalability,and reusability.Additionally,4D printed gradient metamaterial logic gate electronic devices were developed,which were anticipated to contribute to the development of smart,adaptable robotic systems that combine sensing,actuation,and decision-making capabilities.
