Study of Piezoelectricity Applications in Solid Propellants
Open Access
- Author:
- Drewniak, David
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 21, 2022
- Committee Members:
- Richard A Yetter, Thesis Advisor/Co-Advisor
Stefan Thynell, Committee Member
Daniel Haworth, Professor in Charge/Director of Graduate Studies - Keywords:
- piezoelectric
energetic composite
PVDF
nanoaluminum - Abstract:
- New energetic compositions are being investigated for use in solid rocket motors that utilize the piezoelectric properties of polyvinylidene fluoride (PVDF) to tailor the desired sensitivity of solid propellants and energetics. The ability to change a propellants sensitivity could allow solid motors to be ``safed'' prior to use, be used to modulate the thrust of a motor in-flight by changing the burn rate of the propellant, and enable solid state thrust vector control by changing the burn rate asymmetrically. The thesis focuses on the effect piezoelectricity has on the sensitivity to ignition by laser radiation of 10\% wt nanoaluminum/P(VDF-TrFE) composite films. Results from this study show that both the application of an electric field and the activation of the piezoelectric properties of PVDF sensitize the composite as measured by a decrease in a mean time to ignition, with piezoelectricity activation sensitizing the composite to a greater degree than only an applied electric field. Additional research was performed on the effect of piezoelectricity on the steady state burn rate of nanoaluminum/PVDF-based energetic films. A unique two-flame front phenomena was found to occur with some nAl particles, but not others. It was hypothesized that a non-uniform nAl particle distribution resulting from agglomeration was the cause of the two-flame phenomena. Finally, a vastly different experiment was developed to simulate the effects of mechanical oscillation of a propellant surface that may be produced by using piezoelectric to vibrate the surface. Aluminum loaded ammonium perchlorate solid propellant was tested at frequencies of 100 and 500Hz at peak-to-peak displacements of 20, 40, and 80 $\mu$m for 100Hz and 20 $\mu$m for 500Hz. It was found that the burn rate increased by $\sim$8\% over the baseline for 100Hz at a displacement of 80 $\mu$m.