scholarly journals Design of Shape Reconfigurable, Highly Stretchable Honeycomb Lattice With Tunable Poisson’s Ratio

2021 ◽  
Vol 8 ◽  
Author(s):  
Le Dong ◽  
Chengru Jiang ◽  
Jinqiang Wang ◽  
Dong Wang
Keyword(s):  
Theoretical Model ◽  
Ambient Temperature ◽  
Shape Memory ◽  
Poisson’S Ratio ◽  
Lattice Structure ◽  
Poisson's Ratio ◽  
Lattice Structures ◽  
Straight Beam ◽  
Highly Stretchable ◽  
3D Printed

The mechanical behaviors of lattice structures can be tuned by arranging or adjusting their geometric parameters. Once fabricated, the lattice’s mechanical behavior is generally fixed and cannot adapt to environmental change. In this paper, we developed a shape reconfigurable, highly stretchable lattice structure with tunable Poisson’s ratio. The lattice is built based on a hexagonal honeycomb structure. By replacing the straight beam with curled microstructure, the stretchability of the lattice is significantly improved. The Poisson’s ratio is adjusted using a geometric angle. The lattice is 3D printed using a shape memory polymer. Using its shape memory effect, the lattice demonstrates tunable shape reconfigurability as the ambient temperature changes. To capture its high stretchability, tunable Poisson’s ratio and shape reconfigurability, a phase evolution model for lattice structure is used. In the theoretical model, the effects of temperature on the material’s nonlinearity and geometric nonlinearity due to the lattice structure are assumed to be decoupled. The theoretical shape change agrees well with the Finite element results, while the theoretical model significantly reduces the computational cost. Numerical results show that the geometrical parameters and the ambient temperature can be manipulated to transform the lattice into target shapes with varying Poisson’s ratios. This work provides a design method for the 3D printed lattice structures and has potential applications in flexible electronics, soft robotics, and biomedicine.

scholarly journals 3D Printing of Auxetic Shape-Memory Metamaterial Towards Designable Buckling

2021 ◽  
Vol 13 (01) ◽  
pp. 2150011
Author(s):  
Zhenghong Li ◽  
Yuheng Liu ◽  
Yafei Wang ◽  
Haibao Lu ◽  
Ming Lei ◽  
...  
Keyword(s):  
Shape Memory ◽  
Poisson’S Ratio ◽  
Influence Factors ◽  
Maxwell Model ◽  
Thermomechanical Properties ◽  
Poisson's Ratio ◽  
Rate Dependent ◽  
Generalized Maxwell Model ◽  
3D Printed ◽  
Thermomechanical Processes

As one of the most popular 3D printed metamaterials, the auxetic structure with its tunable Poisson’s ratio has attracted huge amount of attention recently. In this study, we designed an auxetic shape-memory metamaterial, which showed designable buckling responses by using the thermomechanically coupled in-plane instability. The influence of viscoelasticity on in-plane moduli and Poisson’s ratios of shape-memory auxetic metamaterial was experimentally investigated. Based on the generalized Maxwell model and finite-element method, the buckling behaviors and their main influence factors were studied. The analytical results and experimental ones showed a good agreement. Thermomechanical properties of the printed metamaterials govern the temperature and strain rate-dependent buckling, and a controllable transition from the negative to positive Poisson’s ratio in the metamaterials can be achieved. Based on the shape memory effect, the buckled state and the Poisson’s ratio of the metamaterials can be tuned by programmed thermomechanical processes. This study provides a simple and efficient way to generate morphing structures using the designable buckling effect.

scholarly journals The Multidirectional Auxeticity and Negative Linear Compressibility of a 3D Mechanical Metamaterial

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2193 ◽  
Author(s):  
Krzysztof K. Dudek ◽  
Daphne Attard ◽  
Ruben Gatt ◽  
James N. Grima-Cornish ◽  
Joseph N. Grima
Keyword(s):  
Theoretical Model ◽  
Poisson’S Ratio ◽  
Three Dimensional ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Structural Units ◽  
Loading Direction ◽  
Arbitrary Loading ◽  
Negative Poisson's Ratio ◽  
Linear Compressibility

In this work, through the use of a theoretical model, we analyse the potential of a specific three-dimensional mechanical metamaterial composed of arrowhead-like structural units to exhibit a negative Poisson’s ratio for an arbitrary loading direction. Said analysis allows us to assess its suitability for use in applications where materials must be able to respond in a desired manner to a stimulus applied in multiple directions. As a result of our studies, we show that the analysed system is capable of exhibiting auxetic behaviour for a broad range of loading directions, with isotropic behaviour being shown in some planes. In addition to that, we show that there are also certain loading directions in which the system manifests negative linear compressibility. This enhances its versatility and suitability for a number of applications where materials exhibiting auxetic behaviour or negative linear compressibility are normally implemented.

scholarly journals Comprehensive Study on Elastic Moduli Prediction and Correlation of Glass and Glass Ceramic Derived from Waste Rice Husk

2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Chee Sun Lee ◽  
Khamirul Amin Matori ◽  
Sidek Hj. Ab Aziz ◽  
Halimah Mohamed Kamari ◽  
Ismayadi Ismail ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Rice Husk ◽  
Poisson’S Ratio ◽  
Elastic Moduli ◽  
Direct Calculation ◽  
Ultrasonic Pulse ◽  
Poisson's Ratio ◽  
Longitudinal Modulus ◽  
Pulse Echo ◽  
Quench Method

Zinc silicate (ZnO–SiO2) systems were fabricated using zinc oxide (ZnO) and white rice husk ash (WRHA) with compositions of (ZnO)x(WRHA)1−x (x = 0.55, 0.60, 0.65, and 0.70 wt.%) was symbolized by S1, S2, S3, and S4, respectively. The ZnO–SiO2 samples were fabricated by applying the melt-quench method and the physical and elastic properties of the samples were investigated. Physical properties used in this study are density and molar volume while the theoretical elastic moduli of the samples produced were obtained using direct calculation of theoretical model compared with the experimental elastic moduli obtained by acquiring ultrasonic velocities using ultrasonic pulse-echo technique. Values of experimental elastic moduli including longitudinal modulus (L), shear modulus (S), Young’s modulus (E), bulk modulus (K), and Poisson’s ratio (σ) were compared with theoretical model calculated using Rocherulle’s model. All the configurations of the elastic moduli obtained experimentally match very well with the configuration from Rocherulle’s model but Poisson’s ratio obtained experimentally differs from the values of Poisson’s ratio obtained through Rocherulle’s model.

A 3D-printed stretchable structural supercapacitor with active stretchability/flexibility and remarkable volumetric capacitance

2020 ◽  
Vol 8 (27) ◽  
pp. 13646-13658 ◽  
Author(s):  
Peng Chang ◽  
Hui Mei ◽  
Yuanfu Tan ◽  
Yu Zhao ◽  
Weizhao Huang ◽  
...  
Keyword(s):  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Negative Poisson's Ratio ◽  
3D Printed ◽  
Volumetric Capacitance

3D-printed stretchable negative Poisson's ratio structural CoNi2S4/NiCo-LDHs-based supercapacitor with active stretchability/flexibility and remarkable volumetric capacitance are built.

scholarly journals Testing of Auxetic Materials Using Hopkinson Bar and Digital Image Correlation

2018 ◽  
Vol 183 ◽  
pp. 02045 ◽  
Author(s):  
Tomáš Fíla ◽  
Petr Zlámal ◽  
Jan Falta ◽  
Tomáš Doktor ◽  
Petr Koudelka ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Poisson’S Ratio ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Lattice Structure ◽  
Frame Rate ◽  
Image Correlation ◽  
Poisson's Ratio ◽  
Strain Gauges

In this paper, a split Hopkinson pressure bar (SHPB) was used for impact loading of an auxetic lattice (structure with negative Poisson’s ratio) at a given strain-rate. High strength aluminum and polymethyl methacrylate bars instrumented with foil strain-gauges were used for compression of an additively manufactured missing-rib auxetic lattice. All experiments were observed using a high-speed camera with frame-rate set to approx. 135.000 fps. High-speed images were synchronized with the strain-gauge records. Dynamic equilibrium in the specimen was analyzed and optimized pulse-shaping was introduced in the selected experiments. Longitudinal and lateral in-plane displacements and strains were evaluated using digital image correlation (DIC) technique. DIC results were compared with results obtained from strain-gauges and were found to be in good agreement. Using DIC, it was possible to analyze in-plane strain distribution in the specimens and to evaluate strain dependent Poisson’s ratio of the auxetic structure.

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