Basic Research Program

Multiscale Modeling of the Structure of Materials for Adaptive Protection

28 April 2009

Dr. Mei ChandlerGeotechnical and Structures

LaboratoryExample

Exa

mpl

e

Multi-scale Modeling of Structure of Materials for Multi-scale Modeling of Structure of Materials for Adaptive ProtectionsAdaptive Protections

Purpose:

To study material responses and failure mechanisms of calcium silicate hydrate phases under quasi-static and dynamic loads at submicron and nano scales. To study the effects of nanoparticle packing, pore solutions and nanopores on the fracture of C-S-H under quasi-static and impact loads.

Results: Dynamic responses of C-S-H phases Effects of nanoparticle packing, nanoparticle interforces,

properties of C-S-H gel on dynamic responses of C-S-H phases

Effects of nanopore solutions on the material response of C-S-H phases

Effects of nanopores and nanocracks on dynamic responses of C-S-H phases Constitutive relations of C-S-H phases with strain rate effects.

Payoff: Develop concrete with superior properties against impact and penetration Establish a modeling methodology for C-S-H phases and other hydrated phases. Obtain constitutive laws of C-S-H phases to be used in

microscale and mesoscale simulation. Those constitutive laws are difficult to determine experimentally.

Provide a foundation in modeling nano-engineered concrete material

Very-High-Strength-Concrete

C-S-H nanostructure

Nanoindenation

Status:Basic 6.1

Milestones 08 09 10

Study interpartical forces

Setup DEM models

DEM simulations and compare to the existing experimental data

In-house experiments and model validation

Parametric studies

Army 6.1 total $250,000 $250,000 $250,000

$_750KTotal Army

Program

What is the Problem? Calcium Silicate Hydrate phases take up to 60% in volume in cement paste and is the glue that holds together all of the components in cement. Yet, the material responses and underlying failure mechanisms of this material under quasi-static and dynamic loads are lacking. The latest research shows that the nanostructure of this material is made up of nanoparticles and behaves in a nano-granual manner. This provides an opportunity for us to model this material at the submicron scales by using the Discrete Element Method. 

What are the barriers to solving the problem?

Morphology of C-S-H nanoparticles is not well established Experiments results are limited

Collaboration across ERDC, commercial firms and/or academia:

Dr. Beverly DiPaolo (GSL) – Co-PI, Experimental testing, materials investigation

Dr. John Peters (GSL) – Co-PI, consultation on DEM methodsDr. Jabari Lee (ITL) _Consultation on Monte Carlo ModelingDr. Daniele Pelesonne (ESSI)_ MARs Dr. Hamlin Jennings (Northwestern)

 What is innovative about this work?In this work, we will model C-S-H phases at the nanoscale and submicron scales, taking into account the experimentally-observed C-S-H nanostructures, and taking into account the physical and chemical forces between C-S-H nanoparticles. This work has not been done at this time.

What is your publication plan? Proposed refereed journal articles –1. Discrete element modeling of nanomechanics of C-S-H2. On the fracture of calcium silicate hydrate under dynamic loads3. Constitutive laws of calcium silicate hydrate at the microscale

How will you overcome these barriers? DEM models will be used to study C-S-H at the

nanoparticle level We will coordinate with other 6.1 projects and design

suitable experiments to validate the models

What are the results of this research and what is its value?

Obtain knowledge of underlying failure mechanisms of C-S-H under quasi-static and dynamic loading

Develop robust constitutive equations to be used in microscale and mesoscale simulations.

Provide insight in nano-engineering concrete material Provide a foundation in modeling nano-engineered

concrete material.

Multi-scale Modeling of Structure of Materials for Adaptive Multi-scale Modeling of Structure of Materials for Adaptive ProtectionsProtections

Accomplishments/Status(1 - 4 Slides)

• Identify major accomplishments through the month prior to the IPR for this work unit. The accomplishments should reflect significant and meaningful scientific contributions or technological achievements, rather than just indicating milestones met.

• Include accomplishments for all years the work unit has been funded.

• Provide expected accomplishments through the end of the current FY.

• Illustrate findings through graphics, tables, charts, photography, equations, etc. Verbally describe significance of findings. Show off your great stuff!

• Describe what actual technology products will be handed off during tech transfer.

• A technical report is NOT considered to be a product. It is the vehicle by which the technology is transferred.

Products

• Describe patent disclosures, patents, etc.

• What other work packages in 6.2/6.3 projects will receive the benefits of this basic research?

Technology Transfer

• Prepare as a separate attachment a list of all publications planned and published for the duration of the project using the spreadsheet template provided.

Publications

• Provide name, organization, and subject area of technical collaborations

Collaborations

Issues

• Issues of major interest are those issues that may cause failure of the work unit to meet the objectives. Typically, issues are of one or two types:– Limited Resources = Personnel + facilities

+ equipment + funds– Scientific/Technical (e.g., results do not

support the hypothesis).