Thesis
Experimental data-driven parameter quantification of structures for research and education
University of Iowa
Master of Science (MS), University of Iowa
Spring 2025
DOI: 10.25820/etd.007901
Abstract
Fluid-structure interactions (FSI) studies the relationship between the solid and fluid dynamics of a fluid-loaded structure. From plane wings to bridges, it is imperative for design engineers to recognize its effects to correctly predict structural parameters. However, current engineering curricula routinely fail to communicate this to undergraduate engineers. At the same time, theory and advanced experimentation in FSI lags decades behind advancements made in the structural dynamics field. Two approaches were taken to address these issues.
First, an experiment seeking to experimentally determine the added mass of a shape was created. This is accomplished using a simple tabletop experiment that is low-cost and simple to build. The experiment makes use of ultrasonic and camera capture data collection techniques; both methods reported added mass values within 5% of theoretical values. The efficacy of the experiment was tested by adapting the lab to an undergraduate level experimentation course project. Students were able to add a third data collection technique–via a load cell–and performed uncertainty analysis on the results.
The second part of this work concerns spatial model realization–a technique aimed at calculating the mass, damping, and stiffness matrices of a structure from experimental vibration data. The finite-element method was used as a synthetic data source to verify results of the method. A first-of-its-kind truncation study was conducted to show the deterioration of realized spatial models with varied numbers of identified modes. Experimental results were obtained from a kinematic shape-sensing (KSS) spar—an aluminum beam equipped with strain gauges and a reconstruction algorithm, enabling measurement of its bending and torsional displacements. The validity of the spar under dynamic loads was determined by comparing the reconstructed displacements to a laser vibrometer, which revealed RMS errors below 0.8 mm and 2.6 cm/s for its position and velocity predictions, respectively. Once validated, the spatial realization technique was performed on data from vibration testing. The realized models suffer from significant truncation error, but retain the identified modal parameters. These results are promising, though further work needs to be completed to ensure the values calculated accurately represent the system.
Details
- Title: Subtitle
- Experimental data-driven parameter quantification of structures for research and education
- Creators
- Connor Hogan
- Contributors
- Casey Harwood (Advisor)Deema Totah (Committee Member)Austin Krebill (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Mechanical Engineering
- Date degree season
- Spring 2025
- DOI
- 10.25820/etd.007901
- Publisher
- University of Iowa
- Number of pages
- xi, 68 pages
- Copyright
- Copyright 2025 Connor Hogan
- Grant note
- This material is based upon work supported by the National Science Foundation under Grant No. 2237542.
- Language
- English
- Date submitted
- 04/29/2025
- Description illustrations
- Illustrations, tables, graphs, charts
- Description bibliographic
- Includes bibliographical references (pages 51-52).
- Public Abstract (ETD)
Better methods to monitor a structure while it is being disturbed by a fluid are important to engineering design. Two solutions were devised to advance this area. First, a simple, tabletop experiment was created to measure the change in a structure’s vibration when it is submerged in water. The experiment is inexpensive, simple to set up, and adaptable. From high school physics to undergraduate engineering courses, it could be used as an effective education tool. The second component of this work sought to use experimental data to better monitor a structure, which could be used to detect failure and optimize designs. The experimentation involved the use of a shape-sensing beam; the beam uses sensors and a mathematical model that make it possible to measure it’s deflections in response to an external force. The beam was validated for the case where it is moving, an important step to make sure the results are suitable for high-precision experiments. While results were good, further work is needed to better use the method on the current experimental setup.
- Academic Unit
- Mechanical Engineering
- Record Identifier
- 9984830920802771
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