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Integrated Fracture Modeling and Integrated Fracture Modeling and Testing ApproachTesting Approach
University of Illinois Research UpdateUniversity of Illinois Research Update
E1 E5
1 5
(c) Field Data and Performance
(d) Lab Testing(a) Fracture Behavior
(b) Bulk Material Response
Computer Simulation
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Bill Buttlar, Glaucio Paulino, Eshan Dave, and Sofie LeonNovember 18, 2009 – Mn/ROAD Maplewood Lab
Review: Task-4Review: Task-4
Develop and validate mixture specification for low-temperature cracking:– Level-I: Mixture fracture test– Level-II: Mixture tests + Modeling
Fracture + Creep + CTE
Task-4:– An executable code that can either be run
standalone or in conjunction with the MEPDG– User-friendly interfaces for data input and
presentation of results– User’s guide with numerical examples that can be
used to verify that the program is working properly
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Level-I, Example (Phase-I)Level-I, Example (Phase-I)
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Mn/ROAD Section-35
TCModel vs. New TCModelTCModel vs. New TCModel
Stress Intensity Factor Model
Fracture Model: Paris Law
Crack Amount Model– Amount of cracking is a function of the
probability that the crack depth is equal to or greater the thickness of the surface layer
Finite Element Based Thermal Cracking Prediction Model with Cohesive Zone Modeling
TCModel New TCModel
Stress Intensity FactorFar-field stress at depth of crack
Current crack length
)99.145.0( 56.00CK
Change in crack depth
Change in stress intensity factorFracture parameters
nKAC )(
Bilinear cohesive zone model
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New TCModel FeaturesNew TCModel Features
Multiple HMA lifts
Viscoelastic bulk material behavior
– IDT creep properties
Cohesive zone fracture model
– Recommended model from the phase-I results
– Uses fracture test results
Finite element analysis engine
– Includes mesh generator
– Non-linear solver
Similar climatic model as MEPDG
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New TCModel StatusNew TCModel Status Completed Tasks
– Finite element analysis code (testing is underway)
– Mesh generator
Tasks underway
– Viscoelastic analysis code (formulations are developed, implementation underway)
– Temperature boundary condition selection
Future Tasks
– Testing of code with all components
– Verification and calibration
– Integration with User Interface (Visual LTC*)
*Developed under NexTrans supplementary study by Sofie Leon
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Visual LTC Analysis ToolVisual LTC Analysis ToolDeveloped on NexTrans Supplementary Developed on NexTrans Supplementary
ProjectProject User-friendly graphical user interface (GUI) to
capture low temperature cracking characteristics of asphalt concrete
Allows for quick yet sophisticated analysis for practical applications
Currently, it is utilizing TCModel (MEPDG) New TCModel will be linked as soon as
implementation and testing is complete
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Visual LTC User TypesVisual LTC User Types
– Practitioners
– Access to all existing mixes
– Default mix properties can be viewed but not changed
– Researchers/Developers
– Access to all existing mixes
– Default mix properties can be viewed and changed
– Modify existing mixes and add new mixes
Standard User Advanced User
Similar to existing MEPDG layout
User can easily switch between user types
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Visual LTCVisual LTC
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Visual LTC ResultsVisual LTC Results
Crack depth with time Amount of cracking with time
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Questions?Questions?
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A
B
t
A
B
Cohesive Zone