Title page for ETD etd-01292008-183718


Type of Document Dissertation
Author He, Xingxi
Author's Email Address xingxi@vt.edu
URN etd-01292008-183718
Title Monte Carlo simulation of ion transport of high strain ionomeric polymer transducers
Degree PhD
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Leo, Donald Committee Chair
Goulbourne, Nakhiah C. Committee Member
Inman, Daniel J. Committee Member
Paul, Mark R. Committee Member
Vlachos, Pavlos P. Committee Member
Weiland, Lisa Committee Member
Keywords
  • ionic polymer transducer
  • morphology
  • Monte Carlo simulation
  • ion hopping model
  • Multiscale modeling
Date of Defense 2008-01-15
Availability unrestricted
Abstract
Ionomeric polymer transducers exhibit electromechanical coupling capabilities. The transport of charge due to electric stimulus is the primary mechanism of actuation for a class of

polymeric active materials known as ionomeric polymer transducers (IPTs). The research

presented in this dissertation focuses on modeling the cation transport and cation steady

state distribution due to the actuation of an IPT.

Ion transport in the IPT depends on the morphology of the hydrated Nafion mem-

brane and the morphology of the metal electrodes. Recent experimental findings show that adding conducting powders at the polymer-conductor interface increases the displacement

output. However, it is difficult for a traditional continuum model based on transport theory to include morphology in the model. In this dissertation, a two-dimensional Monte Carlo

simulation of ion hopping has been developed to describe ion transport in materials that

have fixed and mobile charge similar to the structure of the ionic polymer transducer. In

the simulation, cations can hop around in a square lattice. A step voltage is applied be-

tween the electrodes of the IPT, causing the thermally-activated hopping between multiwell

energy structures. By sampling the ion transition time interval as a random variable, the system evolution is obtained.

Conducting powder spheres have been incorporated into the Monte Carlo simulation. Simulation results demonstrate that conducting powders increase the ion conductivity.

Successful implementation of parallel computation makes it possible for the simulation to include more powder spheres to find out the saturation percentage of conducting powders

for the ion conductivity. To compare simulation results with experimental data, a multiscale model has been developed to increase the scale of Monte Carlo simulation. Both transient responses and steady state responses show good agreement with experimental

measurements.

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