A novel 3D re-entrant unit cell structure with negative Poisson’s ratio and tunable stiffness

2020 ◽  
Vol 29 (4) ◽  
pp. 045015 ◽  
Author(s):  
Dong Li ◽  
Ruicong Gao ◽  
Liang Dong ◽  
Wing-Kai Lam ◽  
Fengpeng Zhang
Keyword(s):  
Poisson’S Ratio ◽  
Cell Structure ◽  
Unit Cell ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Negative Poisson's Ratio ◽  
Tunable Stiffness ◽  
Unit Cell Structure

A unit cell structure with tunable Poisson's ratio from positive to negative

2016 ◽  
Vol 164 ◽  
pp. 456-459 ◽  
Author(s):  
Dong Li ◽  
Liang Dong ◽  
Roderic S. Lakes
Keyword(s):  
Poisson’S Ratio ◽  
Cell Structure ◽  
Unit Cell ◽  
Poisson's Ratio ◽  
Unit Cell Structure

scholarly journals Wave Propagation in Auxetic Tetrachiral Honeycombs

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
K. F. Tee ◽  
A. Spadoni ◽  
F. Scarpa ◽  
M. Ruzzene
Keyword(s):  
Wave Propagation ◽  
Poisson’S Ratio ◽  
Bloch Wave ◽  
Unit Cell ◽  
Poisson's Ratio ◽  
Flexural Wave ◽  
Negative Poisson’S Ratio ◽  
Representative Unit Cell ◽  
Negative Poisson's Ratio ◽  
Phase Constant

This paper describes a numerical and experimental investigation on the flexural wave propagation properties of a novel class of negative Poisson’s ratio honeycombs with tetrachiral topology. Tetrachiral honeycombs are structures defined by cylinders connected by four tangent ligaments, leading to a negative Poisson’s ratio (auxetic) behavior in the plane due to combined cylinder rotation and bending of the ribs. A Bloch wave approach is applied to the representative unit cell of the honeycomb to calculate the dispersion characteristics and phase constant surfaces varying the geometric parameters of the unit cell. The modal density of the tetrachiral lattice and of a sandwich panel having the tetrachiral as core is extracted from the integration of the phase constant surfaces, and compared with the experimental ones obtained from measurements using scanning laser vibrometers.

scholarly journals Negative Poisson’s Ratio-Spacer Design and Its Thermo-Mechanical Coupling Analysis Considering Specific Force Output

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3421
Author(s):  
Qianqian Yuan ◽  
Yongsheng Zhu ◽  
Ke Yan ◽  
Yiqing Cai ◽  
Jun Hong
Keyword(s):  
Poisson’S Ratio ◽  
Cell Structure ◽  
Complex Structure ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Force Output ◽  
Coupling Analysis ◽  
Mechanical Coupling ◽  
Negative Poisson's Ratio ◽  
Bearing Preload

Aiming at the problems of a complex structure or poor controllability of the existing bearing preload control devices, a method of self-regulation via a negative Poisson’s ratio (NPR) spacer is proposed. Firstly, the principle of preload automatic adjustment at the bearing operation was introduced and the NPRs with three types of cell structures were analyzed. Furthermore, a thermo-mechanical coupling analysis model of the NPR spacer was established and the deformation and force output characteristics of the NPR spacer were studied and experimentally verified. It is found that the concave hexagonal cell structure has the optimal deformation characteristics for bearing preload adjustment. When the temperature is considered, the absolute value of Poisson’s ratio of the NPR spacer decreases as the speed increases and the elongation of the NPR spacer and the output forces are much larger than those without temperature consideration. With the increase in temperature or rotating speed, the axial elongation and output forces of the NPR spacer increases while the effect of temperature is relatively larger.

scholarly journals The Negative Poisson’s Ratio Ship Base Design and Vibration Isolation Performance Analysis

2021 ◽  
Vol 11 (23) ◽  
pp. 11167
Author(s):  
Kun Pan ◽  
Jieyu Ding ◽  
Wei Zhang ◽  
Shengdong Zhao
Keyword(s):  
Energy Band ◽  
Poisson’S Ratio ◽  
Vibration Isolation ◽  
Cell Structure ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Hexagonal Cell ◽  
Negative Poisson's Ratio ◽  
Vibration Isolation Performance ◽  
Isolation Performance

This paper mainly studies the vibration isolation of negative Poisson’s ratio structure in the honeycomb base of ships. Based on the structure of the negative Poisson’s ratio structure, different laying methods and different cell structure are used to construct the honeycomb base with the re-entrant hexagonal cell, the mathematical expression of Poisson’s ratio of a single re-entrant hexagonal cell structure is obtained through theoretical analysis. The negative Poisson ratio and relative density could be got by changing the angle and side thickness of the cell structure. Based on the different energy band of the re-entrant hexagonal cell structure, the different negative Poisson’s ratio re-entrant hexagonal honeycomb base was got, the energy band and the frequency response curve of the ship base are analyzed by COMSOL software. The energy band diagram and the frequency response of the structure are obtained to analyze the vibration isolation performance of the honeycomb base. By comparing the experimental results, the following conclusions can be gotten: (1) Compared with the traditional base, the negative Poisson’s ratio base has better vibration isolation effect on external excitation; (2) Different laying method and Poisson ratios can get different isolation effect. The combined base structure can provide better isolation effect to the external excitation in a larger frequency band; (3) By adding different mass blocks to the inner or peripheral angles of the basic re-entrant hexagonal cell, the vibration isolation performance of the structure can be changed to better.

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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