A New Micromechanics Model for Predicting Thermal Properties of Heterogeneous Materials

2006 ◽  
Author(s):  
Wenbin Yu ◽  
Tian Tang
Keyword(s):  
Thermal Properties ◽  
Heterogeneous Materials ◽  
Present Theory ◽  
Unit Cell ◽  
Micromechanics Model ◽  
Micromechanics Models ◽  
Unit Cells ◽  
Variational Asymptotic ◽  
Variational Asymptotic Method ◽  
Complete Set

A new micromechanics model, namely, the variational asymptotic method for unit cell homogenization (VAMUCH), is extended to predict thermal properties of heterogeneous anisotropic materials. In comparison to existing micromechanics models, VAMUCH is unique in the following three aspects: (1) it invokes only essential assumptions within the concept of micromechanics and achieves the same accuracy as mathematical homogenization theories; (2) it calculates the complete set of properties simultaneously without applying any loads; and (3) the dimensionality of the problem is determined by the dimension of the unit cell and the complete set of material properties can be obtained for one-dimensional unit cells. The present theory is implemented in the computer program VAMUCH, a recently developed, versatile engineering code for homogenization of heterogeneous materials. Several examples will be used to demonstrate the application and accuracy of the theory and the code of VAMUCH.

scholarly journals Manipulate Vibration Propagation by Anisotropic Honeycomb Structure

2018 ◽  
Vol 175 ◽  
pp. 03040
Author(s):  
Xiang Chen ◽  
Xiao-ming Wang ◽  
Yu-lin Mei
Keyword(s):  
Design Method ◽  
Honeycomb Structure ◽  
Homogenization Method ◽  
Unit Cell ◽  
Field Analysis ◽  
Acoustic Wave Propagation ◽  
Asymptotic Homogenization ◽  
Fluid Properties ◽  
Asymptotic Homogenization Method ◽  
New Type

As a new type of acoustic metamaterial, the pentamode material has extensive application prospect in controlling acoustic wave propagation because of its fluid properties. Firstly, a kind of pentamode material unit cell is designed, which is a two-dimensional honeycomb truss structure. Then, the asymptotic homogenization method is used to calculate static parameters of the unit cell, and also the influence of the geometric parameters and material composition of the unit cell on its mechanical properties is studied. Besides, based on transformation acoustics and the design method of the cylindrical cloak proposed by Norris, an acoustic cloak with isotropic density and gradient elastic modulus is constructed by periodically assembling the unit cell to guide the wave to bypass obstacles. Finally, the full displacement field analysis is carried out to prove the stealth effect of the acoustic cloak.

Variational asymptotic homogenization of finitely deformed heterogeneous elastomers

2019 ◽  
Vol 216 ◽  
pp. 379-391 ◽  
Author(s):  
Liang Zhang ◽  
Hamsasew M. Sertse ◽  
Wenbin Yu
Keyword(s):  
Asymptotic Homogenization ◽  
Variational Asymptotic

Prediction of Mechanical Properties of Microcellular Plastics Using the Variational Asymptotic Method for Unit Cell Homogenization (VAMUCH) Method

2013 ◽  
Author(s):  
Emily Yu ◽  
Lih-Sheng Turng
Keyword(s):  
Mechanical Properties ◽  
Asymptotic Method ◽  
Thermoplastic Polyurethane ◽  
Three Dimensional ◽  
Unit Cell ◽  
Element Analysis ◽  
Microcellular Plastics ◽  
Variational Asymptotic ◽  
Variational Asymptotic Method ◽  
Injection Molded

This work presents the application of the micromechanical variational asymptotic method for unit cell homogenization (VAMUCH) with a three-dimensional unit cell (UC) structure and a coupled, macroscale finite element analysis for analyzing and predicting the effective elastic properties of microcellular injection molded plastics. A series of injection molded plastic samples — which included polylactic acid (PLA), polypropylene (PP), polystyrene (PS), and thermoplastic polyurethane (TPU) — with microcellular foamed structures were produced and their mechanical properties were compared with predicted values. The results showed that for most material samples, the numerical prediction was in fairly good agreement with experimental results, which demonstrates the applicability and reliability of VAMUCH in analyzing the mechanical properties of porous materials. The study also found that material characteristics such as brittleness or ductility could influence the predicted results and that the VAMUCH prediction could be improved when the UC structure was more representative of the real composition.

A Variational Asymptotic Model for Predicting Initial Yielding Surface and Elastoplastic Behavior of Metal Matrix Composite Materials

2007 ◽  
Author(s):  
Tian Tang ◽  
Wenbin Yu
Keyword(s):  
Metal Matrix ◽  
Energy Functional ◽  
Unit Cell ◽  
Asymptotic Model ◽  
Matrix Composites ◽  
The Finite Element Method ◽  
Elastoplastic Behavior ◽  
Variational Asymptotic ◽  
Variational Asymptotic Method ◽  
Variational Statement

The focus of this paper is to develop a micromechanics model based on the variational asymptotic method for unit cell homogenization (VAMUCH) for predicting of the initial yielding surface, overall instantaneous moduli, and elastoplastic behavior of metal matrix composites. Considering the size of the microstructure as a small parameter, we can formulate a variational statement of the unit cell through an asymptotic expansion of the energy functional. To handle realistic microstructures, we implement this new model using the finite element method. For model validation, we used a few examples to demonstrate the application and accuracy of this theory and the companion code.

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