scholarly journals Erratum to: A composite material with Poisson’s ratio tunable from positive to negative values: an experimental and numerical study

2013 ◽  
Vol 49 (1) ◽  
pp. 461-461 ◽  
Author(s):  
Xiaonan Hou ◽  
Hong Hu ◽  
Vadim Silberschmidt
Keyword(s):  
Composite Material ◽  
Poisson’S Ratio ◽  
Numerical Study ◽  
Poisson's Ratio

Vibrations of Functionally Graded Shells

2007 ◽  
Author(s):  
Serge Abrate
Keyword(s):  
Composite Material ◽  
Modulus Of Elasticity ◽  
Poisson’S Ratio ◽  
Functionally Graded ◽  
New Method ◽  
Poisson's Ratio ◽  
Tabular Form ◽  
Graded Structures ◽  
Functionally Graded Structures

The behavior of functionally graded structures has received a great deal of attention in recent years. Usually, these structures are made out of a composite material with a modulus of elasticity, a Poisson’s ratio, and a density that vary through the thickness. The non-uniformity through the thickness introduces coupling between the transverse deformations and the deformations of the mid-surface. Previous publications have shown how to account for these added complexities and have presented extensive results in tabular form. In this article, available results are used to show that the behavior of functionally graded shells is similar to that of homogeneous isotropic shells. It is well known that for isotropic shells, results can be presented in non-dimensional form so that, once results are obtained for one material, they can be simply scaled to obtain the corresponding results for shells made out of another material. The same can then be done for functionally graded shells. In addition, if functionally graded shells behave like homogeneous shells, no new method of analysis is required. The second part of the paper examines why this is true.

The Influence of Material Variability on the Predicted Environmental Behavior of Composite Materials

1978 ◽  
Vol 100 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Donald F. Adams ◽  
A. Keith Miller
Keyword(s):  
Composite Material ◽  
Poisson’S Ratio ◽  
Moisture Absorption ◽  
Fiber Composite ◽  
Curing Temperature ◽  
Poisson's Ratio ◽  
Ambient Conditions ◽  
Constituent Material ◽  
Graphite Fibers ◽  
Moisture Dependence

The stresses and strains induced in a composite material when subjected to mechanical loads are shown to be strongly influenced by prior exposure to both temperature changes (e.g., cooldown from the curing temperature) and moisture absorption (e.g., even normal exposure to ambient conditions after cure). These environmental effects are in turn influenced by normal variabilities in the basic properties of the composite constituents. Using a recently developed finite element numerical model of composite material inelastic hygrothermal response, variations in stresses and strains are predicted as a function of variations in constituent material properties. A typical graphite/epoxy composite is selected for detailed study. This system is of particular interest because of the anisotropic nature of graphite fibers, and the strong temperature and moisture dependence of the epoxy matrix. Specific fiber property variations considered include transverse modulus, major Poisson’s ratio, and in-plane Poisson’s ratio. Results are compared with those obtained for an isotropic fiber composite.

Experimental Determination of the Poisson's Ratio and the Elastic Modulus of a Sand-Plastic Composite Material

2017 ◽  
Vol 6 (6) ◽  
pp. 292 ◽  
Author(s):  
Moro Olivier Boffoue ◽  
Brahiman Traore ◽  
Conand Honoré Kouakou ◽  
Kokou Esso Atcholi ◽  
Remy Lachat ◽  
...  
Keyword(s):  
Composite Material ◽  
Elastic Modulus ◽  
Experimental Determination ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Plastic Composite

Multilayer Composite Materials with Non-Usual Poisson's Ratios

2007 ◽  
Vol 555 ◽  
pp. 545-552 ◽  
Author(s):  
E.H. Harkati ◽  
Z. Azari ◽  
P. Jodin ◽  
A. Bezazi
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Poisson’S Ratio ◽  
Cellular Materials ◽  
Poisson's Ratio ◽  
Multilayer Composite ◽  
Computer Programme ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

Most of usual materials exhibit Poisson's ratio comprised between 0 and 0.5. But, for some kind of cellular materials, or for some stacking sequences of unidirectional plies, a composite material can exhibit negative or greater than 0.5 Poisson's ratios. In this paper, a study of different stacking sequences such as [±β/±θ]s plies made from highly anisotropic fibre pre-preg is presented. A special computer programme has been developed for this purpose. Eighteen stacking sequences, including the [±θ] ones, have been computed. The results show that at least one of Poisson's ratios varies between -0.8 to +0.4. Such kind of materials may find applications for particular cases, as their strength is significantly increased by this phenomenon.

Design Optimization of Material Properties in a Particle-Filled Composite Material System

2008 ◽  
Author(s):  
Siva P. Gurrum ◽  
Jie-Hua Zhao ◽  
Darvin R. Edwards
Keyword(s):  
Composite Material ◽  
Young’S Modulus ◽  
Material Properties ◽  
Poisson’S Ratio ◽  
Volume Fraction ◽  
Filler Content ◽  
Young's Modulus ◽  
Random Packing ◽  
Poisson's Ratio ◽  
Analytical Models

This work presents a methodology implementing random packing of spheres combined with commercial finite element method (FEM) software to optimize the material properties, such as Young’s modulus, Poisson’s ratio, coefficient of thermal expansion (CTE) of two-phase materials used in electronic packaging. The methodology includes an implementation of a numerical algorithm of random packing of spheres and a technique for creating conformal FEM mesh of a large aggregate of particles embedded in a medium. We explored the random packing of spheres with different diameters using particle generation algorithms coded in MATLAB. The FEM meshes were generated using MATLAB and TETGEN. After importing the nodes and elements databases into commercial FEM software ANSYS, the composite materials with spherical fillers and the polymer matrix were modeled using ANSYS. The effective Young’s modulus, Poisson’s ratio, and CTE along different axes were calculated using ANSYS by applying proper loading and boundary conditions. It was found that the composite material was virtually isotropic. The Young’s modulus and Poisson’s ratio calculated by FEM models were compared to a number of analytical solutions in the literature. For low volume fraction of filler content, the FEM results and analytical solutions agree well. However, for high volume fraction of filler content, there is some discrepancy between FEM and analytical models and also among the analytical models themselves.

scholarly journals A Numerical Study of the Screening Effectiveness of Open Trenches for High-Speed Train-Induced Vibration

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Chih-hung Chiang ◽  
Pei-hsun Tsai
Keyword(s):  
Poisson’S Ratio ◽  
High Speed ◽  
Numerical Study ◽  
Cutoff Frequency ◽  
Poisson's Ratio ◽  
High Speed Train ◽  
High Speed Rail ◽  
Train Speed ◽  
Open Trench ◽  
Screening Effectiveness

This study used the 2D boundary element method in time domain to examine the screening effectiveness of open trenches on reducing vibration generated by a high-speed train. The parameters included configurations of the trench, train speed, the distance between the source and the trench, and the Poisson’s ratio of the soil. A reducing displacement level (in dB scale) was defined and used to evaluate the screening effectiveness of a wave barrier. The maximal reducing displacement level reached 25 dB when an open trench was used as a wave barrier. The depth of an open trench is a main influential parameter of screening effectiveness. The cutoff frequency of the displacement spectrum increases with decreasing trench depth. The maximal screening effectiveness occurs when the depth is 0.3-0.4 Rayleigh wavelength. Using an open trench as a wave barrier can reduce 10–25 dB of vibration amplitude at frequencies between 30 and 70 Hz. A considerable increase in screening effectiveness of the open trench was observed from 30 to 70 Hz, which matches the main frequencies of vibration induced by Taiwan High Speed Rail. The influence of trench width on screening effectiveness is nonsignificant except for frequencies from 30 to 40 Hz. Poisson’s ratio has various effects on the reduction of vibration at frequencies higher than 30 Hz.

Numerical Study on Axial Crushing of Auxetic Foam-Filled Square Tube

2020 ◽  
Vol 975 ◽  
pp. 159-164
Author(s):  
Saeid Mohsenizadeh ◽  
Zaini Ahmad ◽  
Amran Alias
Keyword(s):  
Energy Absorption ◽  
Poisson’S Ratio ◽  
Numerical Study ◽  
Progressive Collapse ◽  
Poisson's Ratio ◽  
Foam Core ◽  
Negative Poisson’S Ratio ◽  
Negative Poisson's Ratio ◽  
Absorption Performance ◽  
Foam Filled

Filling the thin-walled tubes with a foam core is a typical method to enhance the energy absorption performance and stabilize their crushing responses under impact loading. Recently, auxetic foam material with negative Poisson’s ratio has gained remarkable popularity as an effective candidate to enhance the energy absorption capability of structures. In this paper, polyurethane auxetic foam is suggested as a foam core with the negative Poisson’s ratio of-0.31. Numerical simulation was performed to quantify the crush characteristics of auxetic foam-filled square aluminum tubes for variations in initial width of tube under quasi-static axial loading using the nonlinear finite element (FE) code LS-Dyna. Based on the numerical results, the influence of tube width was quantified in terms of energy absorption (EA), specific energy absorption (SEA), initial peak force (Pmax) and crush force efficiency (CFE). It is found that the progressive collapse and deformation modes of auxetic foam-filled tube (AFFT) is pronouncedly affected by varying the tube width. Furthermore, the SEA of AFFT is remarkably sensitive to the tube width variations, yet show low sensitivity to the EA of AFFT. The present study provides new design information on the crush response and energy absorption performance of auxetic foam-filled square tube with varying tube width.

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