A Multiscale Modeling and Experimental Study of the Mechanics of Polymer Nanocomposite Materials

Introduction

This web site gives information on a research project titled "A Multiscale Modeling and Experimental Study of the Mechanics of Polymer Nanocomposite Materials." This project is funded by the Department of Energy. It is being done in the Materials Science & Engineering Department at the University of Utah and at Michigan State University.

Personnel

John A. Nairn

Fracture mechanics and crack propagation
John.Nairn@m.cc.utah.edu

Grant Smith

Molecular dynamics or polymers and interfaces
gsmith@geoffrey.emro.utah.edu

Larry Drzal

Experiments methods in nanocomposites
DRZAL@EGR.MSU.EDU

Dmitry Bedrov

Molecular dynamics or polymers and interfaces
bedrov@tacitus.mse.utah.edu

Scott Bardenhagen

Composite mechanics
bard@lanl.gov

Yajun Guo (post doc)

Fracture mechanics, crack propagation, and mechanics
yguo@eng.utah.edu

Oleg Borodin (post doc)

Composite mechanics and molecular dynamics
borodin@geoffrey.emro.utah.edu

Vinay Srinath (student)

Fracture and composite mechanics
vinay_srinath@hotmail.com

Qingzhu Liu (student)

Molecular dynamics
qliu@cluster2.mse.utah.edu

Sistla Rama Krishna Kishore (student)

Fracture and composite mechanics
sistla_srk@yahoo.co.uk

Guowei Jiang (student)

Molecular dynamics

Shweta Ahuja (student)

Molecular dynamics

Some Recent Results

1. Crack Mechanics in the Material Point Method
   

   Our fracture and mechanics simulations are being done using the material point method (MPM). Our first task was to extend MPM for accurate analysis of bodies with cracks. We have now developed and improved, efficient, and stable algorithm for dynamic analysis of cracks in MPM. The algorithm also accounts for crack surface contact.
   
   Here are some QuickTime movies of MPM simulations with cracks:

   • Five disks impacted in compression with a crack in the central disk
   • Two disks impact with horizontal and vertical cracks
   
   
   
2. Fracture Parameters and Crack Propagation
   

   Once explicit cracks are in MPM, it is possible to due fracture calculations for J integral and stress intensity factor. Once fracture parameters are know, it is possible to calculate conditions for crack growth. We have implemented all these tasks into MPM including complete tracking of crack propagation.
   
   Here is a QuickTime movie for an MPM simulation of mixed-mode crack propagation:

   • Five disks impacted in compression with an angled crack in the central disk
   
   
   

Selected Publications

1. G. D. Smith, D. Bedrov, Liwei Li, and O. Byutner, "A Molecular Dynamics Simulation Study of the Viscoelastic Properties of Polymer Nanocomposites," J. Chem. Phys., 117, 9478-9489 (2002).
2. J. S. Smith, D. Bedrov, and G. D. Smith, "A Molecular Dynamics Simulation Study of Nanoparticle Interactions in Model Polymer-Nanoparticle Composites," Composites Science and Technology, submitted (2002).
3. J. A. Nairn, "Material Point Method Calculations with Explicit Cracks," Computer Modeling in Engineering Sciences, in press (2003). (download PDF reprint)
4. J. A. Nairn "An Energy Balance Approach for Simulation of Crack Growth in Ductile Materials," Polymer Eng. & Sci., submitted (2003).
5. G. D. Smith, D. Bedrov, and O. Borodin, "Structural Relaxation and Dynamic Heterogeneity in a Polymer Melt at Attractive Surfaces," Phys. Rev. Lett., in press, (2003).
6. D. Bedrov, G. D. Smith, and J. S. Smith, "Matrix-induced Nanoparticle Interactions in Polymer Melts. A Molecular Dynamics Simulation Study," J. Chem. Phys., submitted, (2003).
7. S. G. Bardenhagen and E. M. Kober, “The Generalized Interpolation Material Point Method,” Int. J. Numer. Meth. Eng., in press (2003).

Software and Documentation

1. JANFEA MPM and Finite Element Application
   This Macintosh application does finite element analysis and MPM simulation on a Macintosh. It is fully documented with on-line help and has a large number of visualization options. It can be downloaded from the JANFEA Web Site
2. NairnMPM Analysis Source Code
   The MPM sections of JANFEA are also available in C++ source code. This source code is highly portable. The compiled code is best run by taking input files from JANFEA followed by analysis of output files with JANFEA as well. Alternatively, you can prepare your own XML input files and write your own utilities to interpret the results. See NairnMPM Documentation Web Site for information on obtaining the code, compiling and running it, and the format of the input and output files.
3. Lucretius Molecular Dynamics Software
   Lucretius is a general-purpose Molecular Dynamics (MD) simulation program. The code is sufficiently flexible and is able to simulate a wide range of systems without many arbitrary restrictions. The program is highly portable and has been optimized for most of the platforms. The codes are written in FORTRAN and can be download from the Lucretius Web Site.