Coupled Transport/Hyperelastic Model for High Energy Density Nastic Materials

by Homison, Christopher J

Abstract (Summary)
A new development in aerospace technology involves the creation of aircraft that can undergo large changes in the shape of their wings and control surfaces. This technology, called morphing aircraft, does away with several performance compromises by allowing the aircraft to adapt to a wide variety of speed and altitude conditions. One of the challenges associated with the development of morphing aircraft is the creation of a skin that can allow for the in-plane stretching necessary for morphing but possess enough out-of-plane flexural rigidity to handle aerodynamic forces. A new class of high energy density active materials based upon biological processes is being developed to address this problem. These materials utilize the controlled transport of charge and fluid into micron-scale inclusions. The inclusions are phase separated from the surrounding matrix by a selectively-permeable membrane. Selective stimulation of the membrane enables bulk deformation in a process referred to in the plant kingdom as nastic movements. The particular material considered in this work utilizes biological transport mechanisms to generate an osmotic gradient across the membrane. The purpose of this work is to develop a physics-based computational model of the nastic material that couples ion and solvent fluxes generated by the biological transporters to a finite element analysis of the surrounding matrix. This model is to act as a feedback loop for material synthesis efforts. The processes occurring in the biotransport system are complex and highly coupled to one another. The numerical solution of the resulting transport model and its coupling with the finite element analysis are key challenges in creating a viable model. The resulting model has been compared to experiment and is capable of predicting material response over a wide range of configurations and transport components. A series of parametric studies is performed to determine the relative importance of the material parameters and provide guidance to experimental efforts.
Bibliographical Information:

Advisor:Anne M. Robertson, PhD; Lisa Mauck Weiland, PhD; Patrick Smolinksi, PhD

School:University of Pittsburgh

School Location:USA - Pennsylvania

Source Type:Master's Thesis

Keywords:mechanical engineering


Date of Publication:09/27/2006

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