banerjee presentation

8/11/2019 Banerjee Presentation

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Electrical Conductivity Modeling andValidation in Unidirectional CarbonFiber Reinforced Polymer Composites

John L. SchmidtDr. Parag Banerjee

Mechanical Engineering and Materials ScienceWashington University in St. Louis, St. Louis, MO


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Background Why electrical conductivity modeling of carbon fiber

reinforced polymer composites? Lightning strike protection of aircraft Electrostatic discharge/electromagnetic interference

Paur, Wired.com (2009)

10/10/2013 John L. Schmidt Electrical Conductivity of Composites


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Why COMSOL? COMSOL is useful in this study because:

Modeling saves resources It provides a nearly complete suite of software to model:

the current system in three dimensions multiple physics interactions

Electrical

Electrical + Thermal

Electrical + Thermal + Mechanical



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MODEL SETUP


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Basic Model Setup Electric Currents Node within AC/DC Module of

COMSOL Multiphysics (base package)

Potentialapplied ontop surface

Bottom surfacegrounded

Fiberorientation

1 ply

78% fiber loading



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Modeling the Non-Percolation State

Both carbon fiber and polymer are conductive. Carbon fibers contribute very little to the resistance

therefore CF =

Carbonfiber

Polymer resin

ConstantsThermal activation energyElementary chargeTemperatureElectric field

Boggs, et al. , IEEE Trans. Power Del. (2001)



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Modeling the Percolation State

Carbon fiber is the only conductor.

The carbon fiber was considered conductive, and the polymerwas considered virtually non-conductive.

ContactImpedance

Polymer resin

Carbon fiber



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Contact Impedance and Validation

M. Mohiuddin, S. Hoa,Composites Science andTechnology (February 2013)

ExperimentalResult Range

Experimentally, a ply conductivity valueof ~0.04 S/m was found.

Phenomenologically, this indicates acontact resistance exists which is equalto the tunneling distance of 16 ofPEEK.

The resistivity of each node wasapplied from Mohiuddin and Hoa.



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MODELING RESULTS


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The effect of fiber content andverification

A wide range of fiber content was modeled.



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Scaling beyond one ply

1st ply

2nd ply

Interface

Potential applied

Grounded(underneath)

Fiberorientation

Fiberorientation

These verified results can be used to build and analyze larger morecomplicated objects

The number of contacts between two plys was taken into account



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Scaling beyond one ply

Fitting to an equivalent circuit:

Coefficients (R2 = 0.9991):

Rcontact= 1.889e+07 OhmsRblock = 3.534e+05 Ohms Analytical Rblock = 3.37e5 Ohms

These verified results can be used to build and analyze larger morecomplicated objects

The number of contacts between two plys was taken into account


Equivalent Circuit


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(0 , 45 , 90 , 45 , 0 ) Composite Example

This kind of compositeis very frequently usedindustrially.

Overall conductivity ofcomposite:0.0323 S/m with~10x10 contacts ateach interface.



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Conclusions COMSOL Multiphysics can be used to model the electrical

conductivity of carbon fiber reinforced polymer composites. Conductivity models were produced for above and below

the percolation threshold.

The percolation model was validated through agreement withexperimentally determined contact resistance between twofibers.

Electrical conductivity was modeled across the entire CF loadingrange.

These basic models were scaled to a more typical industrialcomposite consisting of multiple plies with different contactconfigurations.



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Acknowledgements

Washington University Department of MechanicalEngineering and Materials Science

Boeing Research & Technology Collaborators: Stephen Heinz and Gregg Bogucki

Washington University Start-up funds

Washington University Nanotechnology ResearchFacility, funded by NSF


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