scholarly journals The Temperature-Sensitive Anisotropic Negative Poisson’s Ratio of Carbon Honeycomb

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 487 ◽  
Author(s):  
Wenrui Wang ◽  
Chenwei He ◽  
Lu Xie ◽  
Qing Peng
Keyword(s):  
Poisson’S Ratio ◽  
Poisson Ratio ◽  
Poisson's Ratio ◽  
Temperature Sensitive ◽  
Three Dimension ◽  
Negative Poisson’S Ratio ◽  
Cell Axis ◽  
Carbon Allotrope ◽  
Negative Poisson's Ratio ◽  
Carbon Honeycomb

We report that carbon honeycomb, a new three-dimension carbon allotrope, exhibits large negative Poisson’s ratio, as large as −0.32, in tensile revealed via molecular dynamics simulations. The Poisson’s ratio of carbon honeycomb is anisotropic, and sensitive to temperature. The carbon honeycomb has phase transformation from normal to auxetic by tensile, along both zigzag and armchair directions. The critical strain for the normal-auxetic transition along the cell-axis direction reduces with respect to an increase in temperature. Combined with high strength of 50 GPa, such a unique and adjustable negative Poisson ratio suggests broad engineering applications of carbon honeycomb.

Development of helical auxetic yarn with negative Poisson’s ratio by combinations of different materials and wrapping angle

2020 ◽  
pp. 152808372094111
Author(s):  
Tehseen Ullah ◽  
Sheraz Ahmad ◽  
Yasir Nawab
Keyword(s):  
Poisson’S Ratio ◽  
Transverse Direction ◽  
Poisson Ratio ◽  
Longitudinal Direction ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
The Core ◽  
Inverse Effect ◽  
Wrap Angle ◽  
Negative Poisson's Ratio

Auxetic materials have negative Poisson ratio which has a multiple ranges of functional applications. The helical auxetic yarn was successfully developed through direct twist system by using core and wrap yarn or filament, which shows Auxeticity when the HAY is stretched in longitudinal direction in response it expand in transverse direction, Helical Auxetic Yarns were developed using various parameters of the core and warp filament, these parameters are wrapping angle (Twist per meter), diameter ratio, and modulus ratio. The strength of Helical yarn was characterized using single yarn strength and Image J software was used for the calculation of poisson’s ratio. According to test results, it is concluded that the core filament of helical auxetic yarn increased its thickness in transverse direction under stress, and a considerable negative poisson’s ratio was calculated. The values of negative poisson’s ratio described that the auxeticity had a direct relation with core filament thickness or diameter and inversely proportional to the linear density of wrap filament, in case of the wrap angle the auxeticity of HAY yarn had an inverse effect with wrap angle. Kevlar/polypropylene combination sample showed maximum auxeticity at a 15-degree angle while Kevlar/nylon combination sample showed minimum auxeticity at a 25-degree wrap angle.

scholarly journals Study on Negative Poisson Ratio and Energy Absorption Characteristics of Embedded Arrow Honeycomb Structure

2020 ◽  
Vol 12 (2) ◽  
pp. 47-57
Author(s):  
Wenzheng Liu ◽  
Shiqing Huang ◽  
Jiachu Xu
Keyword(s):  
Energy Absorption ◽  
Poisson’S Ratio ◽  
Poisson Ratio ◽  
Structural Parameters ◽  
Impact Resistance ◽  
Honeycomb Structure ◽  
Absorption Efficiency ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Negative Poisson's Ratio

 Impact collision exists widely in people's daily life and threatens people's life safety. Negative Poisson's ratio structure has good mechanical properties. Therefore, it is of great significance to design and study the energy absorption structure with negative Poisson's ratio effect. Based on the traditional symmetrical concave honeycomb structure (SCHS) with negative Poisson's ratio, two modified negative Poisson's ratio honeycomb structures are proposed by adding embedded straight rib arrow structure and embedded curved rib arrow structure, which are respectively called embedded straight rib arrow honeycomb structure (SRAH) and embedded curved rib arrow honeycomb structure (CRAH). Through finite element simulation experiment, the negative Poisson's ratio characteristics of two cellular cells were studied and the influence of structural parameters of the cells on the Poisson's ratio was discussed. ANSYS/LS-DYNA was used to analyze the energy absorption of the proposed three cellular structures at different impact velocities. Numerical simulation results show that the SRHS and CRAH have greater stress platform value, specific energy absorption and impact force efficiency than SCHS, indicating that the SRAH and CRAH exhibited better energy absorption efficiency and impact resistance performance.

Free vibration and sound insulation of functionally graded honeycomb sandwich plates

2021 ◽  
pp. 109963622110204
Author(s):  
Fenglian Li ◽  
Wenhao Yuan ◽  
Chuanzeng Zhang
Keyword(s):  
Free Vibration ◽  
Poisson’S Ratio ◽  
Functionally Graded ◽  
Poisson's Ratio ◽  
Dynamic Equations ◽  
Sound Insulation ◽  
Sandwich Plates ◽  
Negative Poisson’S Ratio ◽  
Honeycomb Sandwich ◽  
Negative Poisson's Ratio

Based on the hyperbolic tangent shear deformation theory, free vibration and sound insulation of two different types of functionally graded (FG) honeycomb sandwich plates with negative Poisson’s ratio are studied in this paper. Using Hamilton’s principle, the vibration and vibro-acoustic coupling dynamic equations for FG honeycomb sandwich plates with simply supported edges are established. By applying the Navier’s method and fluid–solid interface conditions, the derived governing dynamic equations are solved. The natural frequencies and the sound insulation of FG honeycomb sandwich plates obtained in this work are compared with the numerical results by the finite element simulation. It is proven that the theoretical models for the free vibration and the sound insulation are accurate and efficient. Moreover, FG sandwich plates with different honeycomb cores are investigated and compared. The corresponding results show that the FG honeycomb core with negative Poisson’s ratio can yield much lower frequencies. Then, the influences of various geometrical and material parameters on the vibration and sound insulation performance are systematically analyzed.

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