Characterization of Raw Material Properties for Optimum LCM Processing

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Characterization of Raw Material Properties for
Optimum LCM Processing Chuck Zhang Florida
Advanced Center for Composite Technologies
(FAC2T) Florida AM University-Florida State
University for NSF/DOE/APC Future of Modeling in
Composites Molding Processes June 9, 2004
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Common Defects in Liquid Composite Molded Parts

• Dry spots
• Dimension variations
• Voids and poor wetting

Variations exist in these defects due to the
variations in raw materials and processing
parameters!
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Modeling and Simulation Can Help Predict Flow and
Dimension Problems
Spring-in by residual stress
Flow-induced dryspot
Effective process modeling and simulation
requires accurate raw material properties!
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Research Issues

• Statistical characterization of raw materials
  properties
• Stochastic modeling and analysis of process and
  defects
• Robust design to improve process reproducibility

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Research Challenges

• Accurate estimation of permeability for complex
  part geometry (modeling)
• In-situ measurement of permeability
  (experimental)
• Statistical permeability characterization
  (modeling experimental)

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Gas-assisted, Real-time ASsessment of
Permeability (GRASP)
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Whole-Field Permeability Estimation with GRASP
Finite element analysis
Fiber preform
High permeability
Low permeability
Computed pressure
Flow validation
Measured pressure
Estimated permeability
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Close Loop LCM Operation with Hardware-In-The-Loop
Simulation
Preform and mold
LCM process
In-situ, whole-field permeability measurement
(GRASP)
GA
Hardware-in-the-loop
NN
Process optimization
Flow simulation
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Statistical Characterization of Fiber
Permeability with GRASP
Woven Carbon Fabrics
Pressure Distribution
Estimated Permeability
Standard Dev. 23.6 of Mean
GRASP may be used to validate permeability
estimation model
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Statistical Characterization of Permeability
Experiment
Kg1, Kr1
Kg2, Kr2
Racetracking permeability
Kgn, Krn
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Summary

• Variations exist in LCM raw materials and
  processing parameters and LCM process performance
  varies due to the variations
• Accurate estimation and statistical
  characterization of permeability are important to
  improve LCM part quality and process
  reproducibility