Several technical needs were identified and addressed for advancing the Strain Energy Accumulator (SEA), which is an energy storage device consisting of an expandable rubber bladder inside of a rigid shroud that stores energy in the form of pressure and strain. First, multiscale modeling methods were investigated to estimate the homogenized elastic modulus of carbon nanotube (CNT) rubber. The result is homogenized modulus estimates ranging from a few times to almost 80 times the elastic modulus of rubber, indicating the need for validation of existing models or development of new models to estimate the modulus for matrix and inclusion materials having drastically dissimilar moduli. Second, an analytical methodology was developed for simultaneously characterizing the energy storage in pneumatic and strain energy systems including component efficiency. By incorporating uncertainty analysis, the efficiencies of the strain energy accumulator are measured in over 2500 cycles of testing to be consistently over 93 %.
Third, system state efficiency models were developed and expanded. Through experimentation, the model was determined to be favorably conservative with system efficiency projections ranging from 31 % to over 60 % depending on the system configuration. In addition, materials challenges in high pressure applications led to the conceptual investigation of CNT elastomers offering improved material strength properties and the potential for self-sensing. In previous research, carbon nanotube sensor thread was tested as a distributed sensor on carbon fiber reinforced composites and was able to monitor strain and detect damage in composite panels. The use of nanomaterials for self-sensing was extended in the current work with proof of concept tests performed on electrically conductive elastomers that exhibited the ability to monitor load and detect damage in specific directions.
Each of these contributions in the areas of materials modeling, uncertainty analysis, and component and system efficiency quantification techniques has helped to advance the Strain Energy Accumulator technology.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-03232016-100719 |
| Date | 28 March 2016 |
| Creators | Cummins, Joshua Joseph |
| Contributors | Douglas E Adams, Eric J Barth, Sankaran Mahadevan, Thomas J Withrow, Florence Sanchez |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-03232016-100719/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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