Ph.D. Thesis Defense

by

Lin Li

(Advisor Professor Julian Rimoli)

STRUCTURAL IMPACTS OF INFLATABLE AERODYAMIC DECELERATOR DESIGN

Time: Friday May 8, 2020. 1:00 pm – 3:00 pm EST

BlueJeans Remote Presentation: https://bluejeans.com/481597554

ABSTRACT

     In order to land larger payloads to Mars, more capable decelerators are required to advance beyond the performance limitations of traditional heritage entry, descent, and landing technologies. One potential technology is an inflatable aerodynamic decelerator (IAD), a flexible aeroshell that can be folded and stowed in a rocket fairing during launch and inflated prior to entry. IADs allow for larger drag areas with minimal mass increase in comparison to traditional rigid aeroshells and, thus, enable improved deceleration performance. However, minimal insight is available regarding the impact of detailed IAD configuration design on their structural performance. Future missions involving IADs will require this structural performance information early in the design cycle in order to develop IADs that have favorable structural and mass performance and are tailorable to specific mission requirements.

This thesis advances the state of the art of inflatable aerodynamic decelerator design by investigating the implications of IAD configuration on their structural and mass performance and developing data analysis techniques to assess an IAD's global dynamic response. These methodologies and results improve future IAD design efforts by enabling estimates of structural performance information in conceptual design, exploring the configurational impacts of novel decelerator designs, and providing new test methodologies to better evaluate those designs. This research, therefore, starts to explore the next phases in the IAD development process, as inflatable decelerator technology maturation transitions from early-stage concept demonstration to applications on future missions that require expanded capabilities beyond the current configurational design space.

In order to inform conceptual design efforts, reduced order models of traditional stacked tori and tension cone decelerators are developed that strategically eliminate complexity in the IAD design to enable rapid simulation of the structural response. These computationally efficient models are used to evaluate the entire configurational design space and enable assessments of the IAD design on their structural and mass performance. A new hybrid decelerator is also developed, leveraging the benefits of the stacked tori and tension cone designs, to provide configurations that better balance mass efficiency with reduced deflection compared to the traditional stacked tori and tension cone designs.

            New data analysis methodologies are also developed to extract information on an IAD’s dynamic response from photogrammetry data. These methodologies allow for visualization of the global IAD dynamic response along with an evaluation of the frequency content of motion. The analysis routines are applied to existing photogrammetry data sets to highlight fundamental characteristics of the decelerator dynamic response and fluid-structure resonance phenomena.

Committee Members:

Dr. Julian Rimoli (advisor)

Dr. Robert Braun (co-advisor)

Dr. Graeme Kennedy

Dr. John Dec

Dr. Neil Cheatwood