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This paper presents a preliminary study of the dynamic performance of a novel light-weight auxetic (negative Poisson’s ratio) cellular vibration isolation base constituted by reentrant hexagonal honeycombs. Numerical and experimental analyses were conducted to reveal the effects of Poisson’s ratio (cell angle) and relative density (cell thickness)...
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Abstract: The elastic properties of cellular structures of sandwich panel cores depend on their density. Density depends on a number of geometric parameters of the core structure. Research is ongoing to find optimal cell sizes with high stiffness of cores and low relative density. The aim of the investigation was to develop mathematical models desc...
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... One of the attractive characteristics of a mechanical metamaterial is its capacity to manipulate wave propagation, which has good potential for various applications, including wave attenuation [9][10][11][12], filtering [13], and guiding [14,15]. To realize these applications, such a metamaterial can suppress wave propagation in a designed direction within the desired frequency band, derived from its bandgap characteristics. ...
A novel three-dimensional mechanical metamaterial with low frequency bandgaps and negative Poisson’s ratio is designed, consisting of a conventional three-dimensional reentrant structure and periodic resonators, with the aim of achieving vibration isolation and impact mitigation. The bandgap characteristic of the proposed metamaterial is determined computationally, and its dispersion diagram exhibits both partial bandgaps and a complete bandgap within a frequency band of interest. The mechanism for bandgap occurrence is characterised as the local resonance of ligaments and resonators, according to a vibration mode analysis. The wave attenuation capacity of the proposed metamaterial is derived numerically and experimentally from semi-infinite and finite-size metamaterial models, showing a good agreement with the predicted bandgap. Additionally, a thorough study on the design flexibility indicates that the bandgap characteristic can be directly tailored by changing the geometrical parameters of the proposed metamaterial. This allows further optimisation of the metamaterial for potential applications. The dynamic performance of the proposed metamaterial under an impact load is investigated by a finite element model. This demonstrates that the metamaterial reduces the transmitted force by a factor of 1.6 (for peak value) and 2.0 (for root mean square value) under a pulse impact with a duration of 0.88 ms. The impact mitigation result obtained from the impact test confirms that the metamaterial shows a mitigation capacity which is approximately 20% better than that of the conventional reentrant structure.
... The rapid developed manufacturing technology has turned imagination into reality nowadays. Now auxetic honeycombs have been adopted to produce aircraft wing, satellite antenna [43,44]; car bumper, buffer system, nonpneumatic tire tire, B-pillar, engine hood [45]; ship isolators, marine platform blast walls [46][47][48][49]; vascular stent, biological implant [50,51], as well as nail, steel pipe concrete, buckling restrained brace, etc. [52][53][54][55] (as shown in Fig. 3). ...
... A common implementation of metamaterials for energy manipulation is for the design of structures with negative or near-zero effective stiffness (auxetic materials) [3,[16][17][18]. These counterintuitive structures have been implemented for energy absorption [19], shock mitigation [20], and vibration isolation [21]. Additional implementations include tailored wave propagation characteristics [22][23][24], frictional unit cells for energy dissipation [12,25], and tailoring structural compliance while limiting energy loss [13,26]. ...
... It was observed that reducing the internal angle of the honeycomb sandwich while maintaining a constant mass constraint resulted in a decrease in its natural frequency and increased resonance in the 1-1000 Hz range, as well as an increase in the sound pressure transmission loss between the resonance frequencies. Zhang [28] et al. discovered that the re-entrant NPR sandwich structure exhibited superior vibration isolation performance compared to the honeycomb structure. At the same time, they also found that reducing its relative density and increasing its Poisson's ratio can enhance the vibration isolation capability of the structure. ...
Due to the influence of mass law, traditional lightweight sandwich structures have struggled to surpass solid structures in sound insulation performance. To this end, we propose an acoustic metamaterial structure with a sandwich configuration based on the re-entrant negative Poisson’s ratio (NPR) structure and systematically investigate its sound transmission loss (STL) performance under incident plane wave conditions. We used the acoustic impedance tube method to experimentally study the sound insulation performance of the re-entrant NPR sandwich structure under free boundary conditions, and then established an acoustic analysis simulation model based on COMSOL Multiphysics software, which verified that the results obtained by the experiment and the numerical simulation were in good agreement. The results show that the sandwich structure exhibits excellent sound transmission loss performance in the studied frequency range (250–4000 Hz), and the overall sound insulation performance exceeds the curve of the mass theorem, basically achieving more than 20 dB when the sandwich thickness is 2 cm. Finally, we conduct parametric studies to establish a correlation between the geometric design of NPR sandwich structures and their sound transmission loss performance. The research shows that the changes of the length of the ribs, the distance from the ribs to the center of the unit, and the length of the upper wall and the lower wall have a significant impact on the sound insulation performance of the re-entrant NPR sandwich structure, while the change of the wall thickness basically will not affect the sound insulation performance of the sandwich structure. This research can provide practical ideas for the engineering application of noise suppression designs of lightweight structures.
... They observed that energy absorption is increased with increase in velocity. Zhang and Yang [26] evaluated the impact of cell angle and cell thickness on the dynamic behaviour of auxetic lattice vibration on re-entrant hexagonal honeycombs. They observed good vibration isolation effect by lowering the cell thickness along with increase in Poisson's ratio. ...
Auxetic cellular structures are a class of advanced structures that possess a negative Poisson’s ratio (NPR) by experiencing lateral expansion/shrinkage under tensile/compressive uniaxial loading. The development of additive manufacturing (AM) technology has made it relatively simple to create complicated shapes, which has gained a lot of attention in auxetic structures as established and novel structural shapes are constructed physically and evaluated to confirm theoretical predictions. In the present research work, an experimental investigation is carried out on re-entrant and anti-tetrachiral auxetic structures fabricated via stereolithography (SLA) based AM technique using Acrylonitrile Butadiene Styrene (ABS) resin. Geometric parameters of re-entrant and anti-tetrachiral auxetic structure are varied to study their influence on the compressive performance namely compression strength, compression modulus and specific energy absorption. Further, the deformation mechanism of auxetic structures is observed in order to comprehend the relationship between the geometric configuration, failure and deformation modes. The compressive behaviour of these auxetic structures is significantly influenced by the selection of geometric parameters. The auxetic structures can offer better mechanical strength and energy absorbing capability via tuning of the geometrical parameters. The findings of this study are anticipated to contribute to a better understanding of the mechanical behaviours of energy-absorbing re-entrant and anti-tetrachiral auxetic structures prepared by SLA because of the absence of such analysis in the specialist literature.
... The opportunity to enhance market income while lowering costs to health care services, global economies, and individual burdens justify sustained study through commercial and public expenditure. Auxetics feature a variety of potentially beneficial properties, including as improved indentation resistance [167][168][169], vibration dampening [170][171][172][173][174], shear modulus [175], and lowered bulk modulus. These have been demonstrated by comparing auxetic foam [176] to its parental and iso-density regular polyurethane foam. ...
... (i) Light-weight cellular vibration isolation base. Reproduced from [20]. CC BY 4.0. ...
... Yang et al [32] fabricated auxetic sandwich panels and tested them for use in low energy impact applications. Vibration damping response of auxetic cellular structures have been examined by Zhang and Yang [20]. The auxetic structures were found to have a superior vibration damping response at a lower weight than conventional structures. ...
... • Size/shape/parametric optimisation [15,20,30]; • Topology optimisation [50,70,75]. ...
Auxetic metamaterials exhibit an unexpected behaviour of a negative Poisson's ratio, meaning they expand transversely when stretched longitudinally. This behaviour is generated predominantly due to the way individual elements of an auxetic lattice are structured. These structures are gaining interest in a wide variety of applications such as energy absorption, sensors, smart filters, vibration isolation and medical etc. Their potential could be further exploited by the use of additive manufacturing. Currently there is a lack of guidance on how to design these structures. This paper highlights state-of-the-art in auxetic metamaterials and its commonly used unit-cell types. It further explores the design approaches used in the literature on creating auxetic lattices for different applications and proposes, for the first time, a workflow comprising design, simulation and testing of auxetic structures. This workflow provides guidance on the design process for using auxetic metamaterials in structural applications.
... The bending and failure of sandwich structures with auxetic gradient cellular cores were investigated by Y. Hou Th al. [4] using the FEM model and experimental results. In 2016, Zhang and Yang [5] published an article about numerical and experimental studies of a light-weight auxetic cellular vibration isolation base. Numerical and experimental analyses were conducted to reveal the effects of Poisson's ratio (known as cell angle) and relative density (known as cell thickness) of the reentrant honeycombs on the dynamic performance of the novel base. ...
In recent years, there has been a new approach to the material industry that uses sandwich structures with auxetic honeycomb cores with the interesting property of negative Poisson's ratios. In this paper, the Finite Element Method (in ANSYS) is used to investigate natural frequency of vibration and bending characteristics under varying pressure loads applied on the top skin when changing fundamental properties of some gradient configurations, including angular gradient, thickness gradient and functional gradient configurations of the auxetic plate with honeycomb structure. Thereby, the advantages of each configuration are investigated, studied, and obtained; therefore, it is expected to be applied in various industry sectors, such as wind turbine blades, aircraft wings, among others.
... Zhang and Yang [140] studied the dynamic performance of a novel lightweight auxetic cellular vibration isolation base constituted by reentrant hexagonal honeycombs. The author proposed design guidelines for the best use of auxetic cellular vibration isolation system. ...
... It was found that decreasing the relative density of reentrant honeycombs and increasing Poisson's ratio of them, substantial vibration isolation performance of auxetic cellular base will be achieved. Duc et al. [141] used analytical solution to investigate the nonlinear dynamic response and vibration of sandwich [134] To evaluate a suspension jounce bumper Double-arrowhead cell Ride comfort test Ma et al. [136] To evaluate a vibration damper Anti-tetrachiral cell Damping performance Essassi et al. [137] Energy dissipation component Reentrant cell Dynamic performance Scarpa et al. [138] To illustrate dynamic characteristics of auxetic foam Auxetic foam Dynamic performance Zhang and Yang [140] To study a vibration isolation base Reentrant cell Dynamic performance Duc et al. [141] Composite cylindrical panel on elastic foundations ...
This manuscript has more than 150 papers as a reference about energy absorption of auxetic structures and shows how several authors have approached the subject and how research in this field has progressed. It can be noted from the present paper that additive manufacturing has been an ally of researchers in the samples manufacturing and numerical analysis has also been widely used by the authors. In addition, this manuscript will provide a context for auxetic structures, discussing some cell models. The results obtained here serve as additional guidelines to assist engineers and designers in the development of auxetic structures.
... A subsequent study by Zhichao Dong et al. [9] on the deformation modes of thick walled and thin walled re-entrant honeycombs proves to be vital in assessing the structures' overall behaviour. Vibrational isolation capacity of the re-entrant honeycomb has been investigated by Zhang et al. [10]. [11,12] carried out works in fabricating auxetic gradient cellular cored sandwich panels to test its load-bearing capacities. ...
Auxetics structures, otherwise known as Negative Poisson’s Ratio structures, respond to a tensile load by expanding laterally and to a compressive load by contracting laterally. A prominent structure of this kind is the re-entrant hexagonal honeycomb. Over the years, studies have been carried out in an attempt to understand the behaviour of such structures in terms of properties like Poisson’s ratio and Young’s modulus, circumventing studies over its load-bearing capacities and potential applications. This paper deals with the latter of the two. Re-entrant structured beams are designed and tested numerically using FE models. Inferior deflection characteristics of the conventional re-entrant beams indicate scope for improvement in the design. An additional design factor of the introduction of filler materials into the voids of cells and its influence is also analysed. Multiple foreign filler materials are introduced in the design to understand the effect of filler materials in deflection characteristics of auxetic beams. Influence of these filler materials, expressed through the ranges of their modulus of elasticity, is recorded and shown. Results obtained from the analysis of beams with filler materials indicate a profitable design with enhancement in deflection characteristics compared to that of the conventional auxetic re-entrant beam.
