scholarly journals Self-Triggered Thermomechanical Metamaterials with Asymmetric Structures for Programmable Response under Thermal Excitations

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2177
Author(s):  
Pengcheng Jiao ◽  
Luqin Hong ◽  
Jiajun Wang ◽  
Jie Yang ◽  
Ronghua Zhu ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Numerical Models ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Thermomechanical Response ◽  
Promising Direction ◽  
Asymmetric Structures ◽  
Mechanical Metamaterials ◽  
Negative Poisson's Ratio ◽  
Advanced Applications

In this study, we propose self-triggered thermomechanical metamaterials (ST-MM) by applying thermomechanical materials in mechanical metamaterials designed with asymmetric structures (i.e., microstructural hexagons and chiral legs). The thermomechanical metamaterials are observed with programmable mechanical response under thermal excitations, which are used in mechanical metamaterials to obtain chiral tubes with negative Poisson’s ratio and microgrippers with temperature-induced grabbing response. Theoretical and numerical models are developed to analyze the thermomechanical response of the ST-MM from the material and structural perspectives. Finally, we envision advanced applications of the ST-MM as chiral stents and thermoresponsive microgrippers with maximum grabbing force of approximately 101.7 N. The emerging ST-MM provide a promising direction for the design and perception of smart mechanical metamaterials.

Qualitative Analysis and Design of Mechanical Metamaterials

2017 ◽  
Author(s):  
Sreekalyan Patiballa ◽  
Girish Krishnan
Keyword(s):  
Qualitative Analysis ◽  
Poisson’S Ratio ◽  
Compliant Mechanisms ◽  
Flow Behavior ◽  
Load Flow ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Analysis And Design ◽  
Mechanical Metamaterials ◽  
Negative Poisson's Ratio

This paper presents a new mechanics-based framework for the qualitative analysis and conceptual design of mechanical meta-materials. The methodology is inspired by recent advances in the insightful synthesis of compliant mechanisms by visualizing a kinetostatic field of forces that flow through the mechanism geometry. The framework relates load flow behavior in the microstructure geometry to the global behavior of the materials, such as auxetic (negative poisson’s ratio), high bulk modulus, and high shear modulus. This understanding is used to synthesize and demonstrate novel planar microstructures that exhibit negative poisson’s ratio behavior. Furthermore, the paper identifies three unique classes of qualitative design problems for planar mechanical microstructures that can be potentially solved using this framework.

Design of Rotational Particle Structure with Negative Poisson’s Ratio Using Numerical Method

2007 ◽  
Vol 544-545 ◽  
pp. 43-46
Author(s):  
Moon Kyu Lee ◽  
Jae Bong Choi ◽  
Kui Won Choi ◽  
H.N. Lim
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Numerical Models ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Convex Shape ◽  
Element Analysis ◽  
Design Variables ◽  
Negative Poisson's Ratio

In the area of biomaterials, the structures with negative Poisson’s ratio are able to be applied to the polymer component of prosthesis, artificial blood-vessel and catheter. To induce its characteristic, previous studies postulated many structural shapes such as non-convex shape with reentrant corners and re-entrant honeycomb. In this study, we proposed the rotational particle structures and investigated the Poisson’s ratio and the ratio (Ee/E) of the elastic modulus of these structures based on structural design variables using finite element method. The auto-meshing preprocessor was coded using MATLAB in order to construct numerical models as design variables and perform finite element analysis (FEA) effectively. Three selected design variables were the ratio of fibril’s length to particle’s diameter (0.2~2.0), the ratio of fibril’s length to its width (0.02~0.2) and the angle of fibril about horizontal axis (0 degree ~ tangential angle). Finite element model has 2D plain stress quadratic element and composed of 515 particles and 6-linked fibrils per each particle. For all of 213 cases, one side of each model is applied a tension, 0.1% strain and analyze Poisson’s ratio and the ratio (Ee/E) of the elastic modulus. As the ratio of fibril’s length to particle’s diameter increased and the ratio of fibril’s diameter to fibril’s length decreased fixing the fibril’s angle with 45 degree, the negative Poisson effect of rotational particle structures increased. The ratio of elastic modulus of these structures decreased with Poisson’s ratio. The results show the reasonable values as compared with the previous analytical results.

scholarly journals Tunable Negative Poisson’s Ratio in Van der Waals Superlattice

Research ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaowen Li ◽  
Xiaobin Qiang ◽  
Zhenhao Gong ◽  
Yubo Zhang ◽  
Penglai Gong ◽  
...  
Keyword(s):  
Poisson’S Ratio ◽  
Electronic Band Structure ◽  
Hexagonal Boron Nitride ◽  
Van Der Waals ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Electronic Band ◽  
Mechanical Metamaterials ◽  
Wide Range ◽  
Negative Poisson's Ratio

Negative Poisson’s ratio (NPR) materials are functional and mechanical metamaterials that shrink (expand) longitudinally after being compressed (stretched) laterally. By using first-principles calculations, we found that Poisson’s ratio can be tuned from near zero to negative by different stacking modes in van der Waals (vdW) graphene/hexagonal boron nitride (G/h-BN) superlattice. We attribute the NPR effect to the interaction of pz orbitals between the interfacial layers. Furthermore, a parameter calculated by analyzing the electronic band structure, namely, distance-dependent hopping integral, is used to describe the intensity of this interaction. We believe that this mechanism is not only applicable to G/h-BN superlattice but can also explain and predict the NPR effect in other vdW layered superlattices. Therefore, the NPR phenomenon, which was relatively rare in 3D and 2D materials, can be realized in the vdW superlattices by different stacking orders. The combinations of tunable NPRs with the excellent electrical/optical properties of 2D vdW superlattices will pave a novel avenue to a wide range of multifunctional applications.

Airfoil Design and Numerical Analysis for Morphing Wing Structure

2011 ◽  
Vol 228-229 ◽  
pp. 169-173 ◽  
Author(s):  
Wen Jun Dong ◽  
Qin Sun
Keyword(s):  
Poisson’S Ratio ◽  
Cellular Structure ◽  
Numerical Models ◽  
Aircraft Design ◽  
Simulation Software ◽  
Poisson's Ratio ◽  
Spanwise Direction ◽  
Negative Poisson’S Ratio ◽  
Morphing Wing ◽  
Negative Poisson's Ratio

This paper investigates an unconventional honeycomb cellular structure featuring a negative Poisson’s ratio with the ability to undergo large overall displacements with limited straining of its solid material in the spanwise direction. Numerical analyses are performed to exploit such properties in the design of a morphing airfoil. The commercial simulation software ANSYS is used to carry on these processes. The cellular structure is designed to satisfy the requirements of configuration changing occurred while wing morphing. Finally, detailed numerical models of the structures are presented as a possible approach to evaluate the stress distribution of the structure. According to simulation results, the airfoil designed in this paper has the property of negative Poisson’s ratio, which is useful to the morphing wing aircraft design.

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