Date of Award
Ph.D. in Physics
University of Mississippi
In an effort to fully characterize the response of a cylindrical helix, the heat and vibrational stresses are modeled using both simulations and experimental testing. The intent of this work is to identify the frequencies, shapes, and Q factors of the vibrational modes of the helix subject to different stimuli and evaluate changes due to environmental exposures and structural modifications. COMSOL Multiphysics is used to simulate the response of the helix under different boundary conditions. Experimental measurements of the response to impulsive and continuous wave stimuli are taken. The eigenfrequency data from the simulations and experiments are then compared for the sake of verifying the simulated resonant frequencies and mode shapes of the helix. We then expand the impulsive stimulus experiments to observe the effects of the rapid heating and cooling of the helix over multiple temperature cycles. Additionally, the effects of added structural elements in the form of a central rod and outer sheath are measured. In these impulsive stimulus experiments, the center frequency, Q factor and amplitude of the mode peaks were compared before and after the modifications to evaluate the effect. Lastly, the data of these resonant modes is used to analyze the symmetry of the elastic modulus tensor for the helix.
Hill, Nathan, "Characterization of Vibrational Response of a Helical Coil Subject to Environmental Exposure and Structural Modifications" (2023). Electronic Theses and Dissertations. 2515.