Micromechanics Modeling of the Nonlinear Behavior of Electrostrictive Multiphase Composites

2008 ◽  
Author(s):  
Tian Tang ◽  
Wenbin Yu
Keyword(s):  
Nonlinear Behavior ◽  
Present Theory ◽  
Unit Cell ◽  
Numerical Examples ◽  
Multiphase Composites ◽  
Variational Asymptotic ◽  
Incremental Formulation ◽  
Variational Asymptotic Method ◽  
Micromechanics Modeling ◽  
Variational Statement

The micromechanics modeling of the nonlinear behavior of the electrostrictive multiphase composites is developed using an incremental formulation based on the variational asymptotic method for unit cell homogenization (VAMUCH), a recently developed micromechanics modeling scheme. The microstructure of composites is assumed to be periodic. Taking advantage of the small size of the microstructure, we formulate a variational statement of energy change of the unit cell through an asymptotic analysis of the functional by invoking only two essential assumptions within the concept of micromechanics. Finally, the expression of the effective instantaneous tangential electromechanical matrix of the composites are established. Several numerical examples will be used to demonstrate the capability of the present theory.

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.

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.

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 Multiphysics Micromechanics Model of Smart Materials Using the Variational Asymptotic Method

2008 ◽  
Author(s):  
Tian Tang ◽  
Wenbin Yu
Keyword(s):  
Asymptotic Method ◽  
Smart Materials ◽  
Effective Properties ◽  
Primary Objective ◽  
Local Fields ◽  
New Model ◽  
Micromechanics Model ◽  
Variational Asymptotic ◽  
Variational Asymptotic Method ◽  
Micromechanics Modeling

The primary objective of the present paper is to develop a micromechanics model for the prediction of the effective properties and the distribution of local fields of smart materials which are responsive to fully coupled electric, magnetic, thermal and mechanical fields. This work is based on the framework of the variational asymptotic method for unit cell homogenization (VAMUCH), a recently developed micromechanics modeling scheme. For practicle use of this theory, we implement this new model using the finite element method into the computer program VAMUCH. For validation, several examples will be presented in the full paper to compare with existing models and demonstrate the application and advantages of the new model.

Asymptotic theory of 3D thermoelastic stress analysis of honeycomb sandwich panels with composite facesheets

2018 ◽  
Vol 22 (6) ◽  
pp. 1952-1982
Author(s):  
MV Peereswara Rao ◽  
K Renji ◽  
Dineshkumar Harursampath
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Present Theory ◽  
Two Dimensional ◽  
Composite Sandwich ◽  
Variational Asymptotic ◽  
Small Parameters ◽  
Dimensional Finite Element ◽  
Variational Asymptotic Method ◽  
Three Dimensional Finite Element

This work presents an asymptotical thermoelastic model for analyzing symmetric composite sandwich plate structures. Use of three-dimensional finite elements to analyze real-life composite sandwich structures is computationally prohibitive, while use of two-dimensional finite element cannot accurately predict the transverse stresses and three-dimensional displacements. Endeavoring to fill this gap, the present theory is developed based on the variational asymptotic method. The unique features of this work are the identification and utilization of small parameters characterizing the geometry and material stiffness coefficients of sandwich structural panels in addition to the small parameters pertaining to any plate-like structure. In this formulation, using variational asymptotic method, the three-dimensional thermoelastic problem is mathematically split into a one-dimensional through-the-thickness analysis, and a two-dimensional reference surface analysis. The through-the-thickness analysis provides the constitutive relation between the generalized two-dimensional strains, and the generalized force resultants for the plate analysis, it also provides a set of closed-form solutions to express the three-dimensional responses in terms of two-dimensional variables, which are determined by solving the equilibrium equations of the plate reference surface. Numerical results are illustrated for a typical composite sandwich panel subjected to a linear-bisinusoidal thermal loading. The three-dimensional responses of the composite sandwich structure from the present theory are compared with the three-dimensional finite element solutions of MSC NASTRAN®. The results from the present theory agree closely with three-dimensional finite element results and yet enable order of magnitude saving in computational resources and time.

Sign in / Sign up

Export Citation Format

Share Document