scholarly journals Parametric Study of Non-periodic and Hybrid Auxetic Bending-Active Gridshells

2020 ◽  
Vol 61 (4) ◽  
pp. 275-284
Author(s):  
Yusuke Sakai ◽  
Makoto Ohsaki
Keyword(s):  
Poisson’S Ratio ◽  
Design Method ◽  
Plane Deformation ◽  
Design Tool ◽  
Poisson's Ratio ◽  
Curved Surface ◽  
Free Form ◽  
Deformation Analysis ◽  
Curved Surfaces ◽  
Shape Parameters

This paper presents a design method of Auxetic Bending-Active Gridshells (ABAGs), which are curved surfaces generated from the initial flat grid with 2-dimensional auxetic patterns. One of the mechanical properties of ABAGs is that a dome-like shape of a curved surface can be easily obtained by bending a grid due to negative Poisson's ratio for in-plane deformation. Shapes of auxetic patterns are relevant to Poisson's ratio. Non-periodic and/or hybrid 2-dimensional auxetic patterns are developed for designing the initial flat grid of ABAGs. Shape parameters are the sizes of each plane unit for tuning its reentrant pattern, and two types of reentrant shapes are mixed on an initial flat grid. Using the non-uniform patterns, we can obtain an asymmetric and more complex free-form surface of ABAGs than those composed of a uniform reentrant pattern. Discrete Gaussian curvature at each node on a curved surface is computed for quantitatively evaluating the properties of shapes of the obtained surfaces. Possibility of ABAGs as a new design tool is demonstrated by showing that various shapes are generated through large deformation analysis with the forced displacements at the supports.

Kinematics of the Morph Origami Pattern and its Hybrid States

2020 ◽  
Author(s):  
Phanisri P. Pratapa ◽  
Ke Liu ◽  
Glaucio H. Paulino
Keyword(s):  
Configuration Space ◽  
Poisson’S Ratio ◽  
Plane Deformation ◽  
Mode Locking ◽  
Unit Cell ◽  
Poisson's Ratio ◽  
Form Complex ◽  
Mountain Valley ◽  
Characteristic Modes ◽  
Unit Cells

Abstract A new degree-four vertex origami, called the Morph pattern, has been recently proposed by the authors (Pratapa, Liu, Paulino, Phy. Rev. Lett. 2019), which exhibits interesting properties such as extreme tunability of Poisson’s ratio from negative infinity to positive infinity, and an ability to transform into hybrid states through rigid origami kinematics. We look at the geometry of the Morph unit cell that can exist in two characteristic modes differing in the mountain/valley assignment of the degree-four vertex and then assemble the unit cells to form complex tessellations that are inter-transformable and exhibit contrasting properties. We present alternative and detailed descriptions to (i) understand how the Morph pattern can smoothly transform across all its configuration states, (ii) characterize the configuration space of the Morph pattern with distinguishing paths for different sets of hybrid states, and (iii) derive the condition for Poisson’s ratio switching and explain the mode-locking phenomenon in the Morph pattern when subjected to in-plane deformation as a result of the inter-play between local and global kinematics.

scholarly journals Structural Modelling of Automotive Engine Mounting from Kenaf Fibre Reinforced Natural Rubber/Thermoplastic Polyurethane “Green” Composites

2019 ◽  
Vol 8 (2S4) ◽  
pp. 445-449
Keyword(s):  
Natural Rubber ◽  
Poisson’S Ratio ◽  
Thermoplastic Polyurethane ◽  
Simulation Software ◽  
Poisson's Ratio ◽  
Deformation Analysis ◽  
Automotive Engine ◽  
Ansys Simulation ◽  
New Material ◽  
Stress Simulation

This paper presents an investigation of deformation analysis using ANSYS of automotive engine rubber mount made from kenaf fiber reinforced natural rubber (NR)/thermoplastic polyurethane (TPU) composites. The modelling of mounting was conducted using CATIA software. To determine the of the Poisson’s ratio of this new material composites is important, which was required data to be filled into the ANSYS software. The Poisson’s ratio was calculated based on the previous data experiment from the stress-strain results. The analysis was focussing on the deformation and stress analysis effected from the pressure that was applied in the modelling and in the ANSYS simulation software which is 250 psi. The deformation and stress simulation results were then identified and discussed and the results were compared to the Natural Rubber material of the same design simulation.

scholarly journals Design Method of Lightweight Metamaterials with Arbitrary Poisson’s Ratio

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1574 ◽  
Author(s):  
Haoxing Qin ◽  
Deqing Yang ◽  
Chenhui Ren
Keyword(s):  
Poisson’S Ratio ◽  
Optimization Problem ◽  
Design Method ◽  
Vibration Reduction ◽  
Functional Element ◽  
Deformation Resistance ◽  
Poisson's Ratio ◽  
The Novel ◽  
Stiffness Analysis ◽  
Absolute Value

A heuristic approach to design lightweight metamaterials with novel configurations and arbitrary Poisson’s ratio is studied by using the functional element topology optimization (FETO) method. Mathematical model of the optimization problem is established, where the minimization of the mass is set as the objective, then a series of metamaterials with Poisson’s ratio ranging from −1.0 to +1.0 are designed by solving this model. The deformation resistance and vibration reduction performance of the novel metamaterials and conventional honeycomb are compared by numerical simulations. Specific stiffness analysis shows that the novel metamaterials are 5.6 to 21.0 times more resistant to deformation than that of the honeycomb, and frequency response shows about 60% improvement in vibration reduction performance. Finally, the lightweight effects of the novel metamaterials on deformation resistance and vibration reduction performance are analyzed, and further analysis reflects that the lightweight effects increase with the increase of the absolute value of the Poisson’s ratio.

The Model for Calculating Elastic Modulus and Poisson's Ratio of Coal Body

2013 ◽  
Vol 6 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Ai Chi ◽  
Li Yuwei
Keyword(s):  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Fractured Rock ◽  
Rock Block ◽  
Poisson's Ratio ◽  
Linear Elastic ◽  
Study Results ◽  
The Face ◽  
Block Face ◽  
Coal Rock

Coal body is a type of fractured rock mass in which lots of cleat fractures developed. Its mechanical properties vary with the parametric variation of coal rock block, face cleat and butt cleat. Based on the linear elastic theory and displacement equivalent principle and simplifying the face cleat and butt cleat as multi-bank penetrating and intermittent cracks, the model was established to calculate the elastic modulus and Poisson's ratio of coal body combined with cleat. By analyzing the model, it also obtained the influence of the parameter variation of coal rock block, face cleat and butt cleat on the elastic modulus and Poisson's ratio of the coal body. Study results showed that the connectivity rate of butt cleat and the distance between face cleats had a weak influence on elastic modulus of coal body. When the inclination of face cleat was 90°, the elastic modulus of coal body reached the maximal value and it equaled to the elastic modulus of coal rock block. When the inclination of face cleat was 0°, the elastic modulus of coal body was exclusively dependent on the elastic modulus of coal rock block, the normal stiffness of face cleat and the distance between them. When the distance between butt cleats or the connectivity rate of butt cleat was fixed, the Poisson's ratio of the coal body initially increased and then decreased with increasing of the face cleat inclination.

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