scholarly journals Fish Cells, a new zero Poisson’s ratio metamaterial—Part I: Design and experiment

2020 ◽  
Vol 31 (13) ◽  
pp. 1617-1637
Author(s):  
Mohammad Naghavi Zadeh ◽  
Iman Dayyani ◽  
Mehdi Yasaee
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Poisson’S Ratio ◽  
Structural Integrity ◽  
Structural Response ◽  
Poisson's Ratio ◽  
Experimental Investigations ◽  
Fish Cells ◽  
Force Displacement ◽  
Model Approach

A novel cellular mechanical metamaterial called Fish Cells that exhibits zero Poisson’s ratio in both orthogonal in-plane directions is proposed. Homogenization study on the Fish Cells tessellation is conducted and substantially zero Poisson’s ratio behavior in a homogenized tessellation is shown by numerical analysis. Experimental investigations are performed to validate the zero Poisson’s ratio feature of the metamaterial and obtain force–displacement response of the metamaterial in elastic and plastic zone. A detailed discussion about the effect of the numerical model approach and joints on the structural response of the metamaterial is presented. Morphing skin is a potential application for Fish Cells metamaterial because of the integration benefits of zero Poisson’s ratio design. The structural integrity of the Fish Cells is investigated by studying the stiffness augmentation under tension and in presence of constraints on transverse edges. Finally, geometrical enhancements for improved integrity of the Fish Cells are presented that result in substantially zero stiffness augmentation required for morphing skins.

Energy Absorption of an Re-Entrant Honeycombs with Negative Poisson’s Ratio

2011 ◽  
Vol 148-149 ◽  
pp. 992-995 ◽  
Author(s):  
Shu Yang ◽  
Chang Qi ◽  
Dong Ming Guo ◽  
Dong Wang
Keyword(s):  
Energy Absorption ◽  
Poisson’S Ratio ◽  
Structural Response ◽  
Rigid Wall ◽  
Geometrical Model ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Explicit Finite Element ◽  
Good Ability ◽  
Negative Poisson's Ratio

In the present paper, we have investigated a negative Poisson’s ratio structure with regular re-entrant cell shape to study its structural response under crush by rigid wall. Firstly, we created the geometry of cellular material in HYPERMESH. The developed geometrical model is imported into LS-DYNA. Then we use commercially available nonlinear explicit finite element code LS-DYNA to simulate the NPR material under uniformly distributed load. The deformation modes and energy absorption characteristics of NPR material were analyzed. Numerical results indicate that this NPR material have good ability of energy absorption.

scholarly journals Análise numérica de ligação parafusada semirrígida em perfis formados a frio

ForScience ◽  
2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Emerson Cardoso de Castro ◽  
Flávio Teixeira de Souza ◽  
Arlene Maria Cunha Sarmanho
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Finite Elements ◽  
Three Dimensional ◽  
Structural Performance ◽  
Similar Tendency ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Bolt Connection ◽  
Force Displacement

O presente trabalho constitui-se de uma análise numérica, por meio de elementos finitos, objetivando a reprodução via software de um ensaio experimental de ligação parafusada semirrígida em perfis formados a frio, dada no âmbito tridimensional. A análise consistiu-se a partir da reprodução da geometria do protótipo, das condições de contorno e aplicação de carregamento. Para melhor previsão do comportamento da ligação, foram inseridas ao modelo a não linearidade física e geométrica. Foram obtidas as curvas força-deslocamento e a evolução das tensões de Von Mises para os diferentes componentes do protótipo. Os resultados indicaram que o modelo numérico é cerca de duas vezes mais rígido que o experimental. Todavia, foi possível observar que o comportamento do modelo numérico possui tendência similar ao do modelo experimental e também foi possível avaliar a contribuição dos elementos da ligação para o desempenho da mesma.Palavras-chave: Análise numérica. Ligação parafusada semirrígida. Perfis formados a frio. Desempenho estrutural.Numerical analysis of semi-rigid bolt connection in cold formed profilesAbstractThe current paper is based on a numerical analysis by means of finite elements aiming at the software reproduction of an experimental test of semi-rigid bolt connection in cold formed profiles occurred in the three-dimensional scope. The analysis consisted of the reproduction of the prototype geometry, the boundary conditions, and the loading application. For a better forecast of the connection behavior, physical and geometric non-linearity were inserted to the model. The force-displacement curves and the evolution of the Von Mises stresses for the different prototype components were obtained. The results indicated that the numerical model is about twice as rigid as the experimental one. However, it was possible to observe that the behavior of the numerical model has a similar tendency  if compared to  the experimental model and it was still possible to evaluate the contribution of the connection elements to its performance.Keywords: Numerical analysis. Semi-rigid bolt connection. Cold-formed profiles. Structural performance.

Numerical Analysis of Fire Performance of a Spacial Pre-Stressed Steel Structure in Fire

2013 ◽  
Vol 790 ◽  
pp. 189-192
Author(s):  
Tian Hong Wang ◽  
Jin Can Xu ◽  
Hai Lun Tong ◽  
Xin Tang Wang
Keyword(s):  
Thermal Expansion ◽  
Numerical Analysis ◽  
Numerical Model ◽  
Stress Relaxation ◽  
Thermal Response ◽  
Structural Response ◽  
Steel Structure ◽  
Fire Performance ◽  
Maximum Value ◽  
In Fire

The numerical model of analysis of fire performance of a spatial pre-stressed steel structure with large span was established based on the software Marc. The thermal response and structural response of the pre-stressed steel structure was computed for some nodes of the structure in fire. The different fire scenes were considered for analysis of response temperature, displacements and stresses of the nodes of the pre-stressed steel structure.It is concluded that the temperature rise of the nodes of the structure is far behind that of air near the nodes, however they are quite close as the fire lasted for 3600s and almost the same after 7200s.The results show that the displacement of the node right above the inner cable is the maximum and the node above the outer cable has the smallest value of displacement and the maximum value is about two and half times as large as the minimum.The results show that the reason why the cables are out of work is that the equilibrium between the cables and the rods of the structure is lost, but not that the stress relaxation caused by thermal expansion make the cables out of work.

scholarly journals Numerical and Experimental Studies of a Light-Weight Auxetic Cellular Vibration Isolation Base

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Xiang-Wen Zhang ◽  
De-Qing Yang
Keyword(s):  
Numerical Analysis ◽  
Relative Density ◽  
Poisson’S Ratio ◽  
Vibration Isolation ◽  
Dynamic Performance ◽  
Experimental Studies ◽  
Design Guidelines ◽  
Poisson's Ratio ◽  
Light Weight ◽  
Isolation System

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) of these reentrant honeycombs on the dynamic performance of this novel base and to propose design guidelines for the best use of the auxetic cellular vibration isolation system. By doing numerical analysis, we found that, by decreasing the relative density of reentrant honeycombs and increasing Poisson’s ratio of them, excellent vibration isolation performance of the auxetic cellular base will be achieved. This analysis was followed by static, modal, and frequency response tests, which verified the results of the numerical analysis.

Crashworthiness analysis of cylindrical tubes with coupling effects under quasi-static axial loading: An experimental and numerical study

2021 ◽  
pp. 146442072110533
Author(s):  
Hassan Mansoori ◽  
Ramin Hamzehei ◽  
Soheil Dariushi
Keyword(s):  
Energy Absorption ◽  
Poisson’S Ratio ◽  
Absorption Capacity ◽  
Negative Stiffness ◽  
Poisson's Ratio ◽  
Energy Absorption Capacity ◽  
Element Analysis ◽  
Assembly Method ◽  
Cylindrical Tubes ◽  
Force Displacement

In most cylindrical tubes, the occurrence of negative stiffness under compression is unavoidable. This downward trend in the force–displacement relationship means a decrease in the energy-absorption capacity. To this end, this paper introduces a new assembly method comprising two concentric cylindrical tubes. The inner cylinder possesses positive Poisson's ratio behavior, whereas the outer cylinder exhibits negative Poisson's ratio behavior. When compressed, the outer and inner cylinders shrink and expand, respectively, creating surface contacts between the two cylinders, called coupling effects. This property not only avoids the occurrence of negative stiffness in outer cylindrical tube, but also increases the energy-absorption capacity in an upward trend in the force–displacement relationship. To confirm this claim, three different types of cylindrical tubes, possessing positive Poisson’s ratio, zero Poisson's ratio, and negative Poisson’s ratio behaviors, are considered. A finite-element analysis is implemented to simulate deformation patterns of cylindrical tubes. Then, to verify the results of finite-element analysis, a laser-cutting method is applied to fabricate cylindrical tubes from stainless steel tubes. The results show that the proposed assembly method increases the energy-absorption capacity by up to 95% compared to the well-known auxetic tube. Next, a parametric study is performed, in which the gap space between the two cylinders is considered as a design variable. The results reveal the smaller the gap space, the higher the energy-absorption capacity. The absorbed energy in the assembled cylinders without gap space is 17.6 J, which is 36% greater than that of cylinders with 13 mm gap space. The effects of relative density and crushing speed are also evaluated. When compared to the crushing speed, the energy-absorption capacity is highly dependent on relative density.

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