Three-dimensional porous borocarbonitride BC2N with negative Poisson's ratio

2020 ◽  
Vol 8 (44) ◽  
pp. 15771-15777
Author(s):  
Kashif Hussain ◽  
Umer Younis ◽  
Imran Muhammad ◽  
Yu Qie ◽  
Yaguang Guo ◽  
...  

Motivated by the recent synthesis of three-dimensional (3D) porous borocarbonitride (Angew. Chem., Int. Ed., 2019, 58, 6033–6037), we propose a porous 3D-BC2N structure composed of BC2N nanoribbons.

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2193 ◽  
Author(s):  
Krzysztof K. Dudek ◽  
Daphne Attard ◽  
Ruben Gatt ◽  
James N. Grima-Cornish ◽  
Joseph N. Grima

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.


Author(s):  
ChunYan Wang ◽  
SongChun Zou ◽  
WanZhong Zhao

The crash box can absorb energy from the beam as much as possible, so as to reduce the collision damage to the front part of the car body and protect the safety of passengers. This work proposes a novel crash box filled with a three-dimensional negative Poisson’s ratio (NPR) inner core based on an inner hexagonal cellular structure. In order to optimize and improve the crash box’s energy absorption performance, the multi-objective optimization model of the NPR crash box is established, which combines the optimal Latin hypercube design method and response surface methodology. Then, the microstructure parameters are further optimized by the multi-objective particle swarm optimization algorithm to obtain an excellent energy absorption effect. The simulation results show that the proposed NPR crash box can generate smooth and controllable deformation to absorb the total energy, and it can further enhance the crashworthiness through the designed optimization algorithm.


2011 ◽  
Vol 21 (14) ◽  
pp. 2712-2720 ◽  
Author(s):  
David Y. Fozdar ◽  
Pranav Soman ◽  
Jin Woo Lee ◽  
Li-Hsin Han ◽  
Shaochen Chen

Author(s):  
Joseph N. Grima ◽  
Roberto Caruana-Gauci ◽  
Daphne Attard ◽  
Ruben Gatt

A three-dimensional cellular system that may be made to exhibit some very unusual but highly useful mechanical properties, including negative Poisson's ratio (auxetic), zero Poisson's ratio, negative linear and negative area compressibility, is proposed and discussed. It is shown that such behaviour is scale-independent and may be obtained from particular conformations of this highly versatile system. This model may be used to explain the auxetic behaviour in auxetic foams and in other related cellular systems; such materials are widely known for their superior performance in various practical applications. It may also be used as a blueprint for the design and manufacture of new man-made multifunctional systems, including auxetic and negative compressibility systems, which can be made to have tailor-made mechanical properties.


2020 ◽  
Vol 31 (15) ◽  
pp. 1838-1852
Author(s):  
Ehsan Jebellat ◽  
Majid Baniassadi ◽  
Alireza Moshki ◽  
Kui Wang ◽  
Mostafa Baghani

Today, the human being endeavors to manufacture devices and materials capable of doing something in an intelligent way. Shape memory polymers are a series of smart materials, capable of retrieving their original shape from a temporary form by applying external stimuli, for example, heat, electricity, magnetism, light, pH, and humidity. In this research, the behavior of temperature-sensitive shape memory polymer–based structures with positive and negative Poisson’s ratio has been analyzed. The purpose is the material design of smart structures with tunable Poisson’s ratio using topology optimization. In this study, a meta-structure is designed, which is made by a smart material. Not only does this structure have shape memory effects, but also it has negative Poisson’s ratio, which can be used in new sensors, actuators, and biomedical applications. After creation of the unit cell and the representative volume element and formation of final three-dimensional structure, finite element modeling is conducted based on a thermo-visco-hyperelastic constitutive model at large deformations. Examining the behavior of structures in tensile pre-strains of 20%, 10%, and 5%, it is observed that pre-strain has no considerable effect on Poisson’s ratio, but under compressive strain of 20%, it is concluded that the type of loading is effective on Poisson’s ratio and the results are different in tension and compression modes. Finally, the influence of temperature rate on the behavior of structures is inspected, and it is concluded that the more slowly the temperature changes, the more strain or shape recovery is accomplished at a specific temperature.


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