Microvascular composites as a multifunctional material for electric vehicles

Electric vehicle (EV) batteries require both thermal regulation and structural protection. A novel form of battery packaging is proposed to accomplish this multifunctional objective using microvascular fiber-reinforced composites. Batteries are sandwiched between carbon fiber/epoxy panels containing embedded microchannels. Coolant flow enables active cooling while the composite material provides strength, stiffness, and crashworthiness at low weight. Several studies are performed on the cooling performance of microvascular panels. First, thermography experiments and computational fluid dynamics (CFD) simulations are used to characterize the cooling performance of carbon/epoxy panels with straight 500 µm diameter microchannels. Panels with high enough channel density and coolant flow rate can sufficiently cool batteries below 40 °C for applied heat fluxes up to 1000 W m-2. Next, experiments and simulations are performed on carbon/epoxy panels with more complex 2D microvascular networks (parallel, bifurcating, serpentine, and spiral networks). The spiral network offers optimal thermal performance at high pumping pressure (>100 kPa), while the bifurcating network and a computationally optimized parallel network offer slightly reduced thermal performance at much lower pumping pressure (<10 kPa). In a collaborative effort, gradient-based optimization is used to improve the blockage tolerance of microvascular networks. Optimizations are performed on networks with different nodal degree (a measure or redundancy) to minimize temperature while the network is subject to a blockage. Tests on microvascular silicone panels confirm that optimized networks with high nodal degree experience minimal temperature rises when blocked. Finally, crush tests are performed on microvascular carbon/epoxy panels to demonstrate how channels affect composite crashworthiness. Corrugated panels are fabricated containing 400 µm channels at different spacing (10 mm and 1.2 mm), orientation with respect to the load (transverse and longitudinal), and orientation with respect to surrounding plies. Crush tests revealed no significant reduction in specific energy absorbed (SEA) for all test cases. Further tests demonstrate that microchannels can actually improve composite crashworthiness by triggering stable, energy-absorbing failure modes in flat panels.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Materials Science & Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2017

Author dc:creator

• Pety, Stephen J.

Contributors dc:contributor

• White, Scott R.
• Sottos, Nancy R.
• Geubelle, Philippe H.
• Braun, Paul V.
• Evans, Christopher M.

• Microvascular composites
• Multifunctional materials
• Battery cooling
• Thermal imaging
• Computational fluid dynamics
• Crashworthiness
• Carbon fiber

Statement dc:rights

• Copyright 2017 Stephen J. Pety

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/97373

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/97373