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Investigation of hypervelocity impact phenomena using real-time concurrent diagnostics

Citation

Mihaly, Jonathan Michael (2013) Investigation of hypervelocity impact phenomena using real-time concurrent diagnostics. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:06072013-143355354

Abstract

Hypervelocity impact of meteoroids and orbital debris poses a serious and growing threat to spacecraft. To study hypervelocity impact phenomena, a comprehensive ensemble of real-time concurrently operated diagnostics has been developed and implemented in the Small Particle Hypervelocity Impact Range (SPHIR) facility. This suite of simultaneously operated instrumentation provides multiple complementary measurements that facilitate the characterization of many impact phenomena in a single experiment. The investigation of hypervelocity impact phenomena described in this work focuses on normal impacts of 1.8 mm nylon 6/6 cylinder projectiles and variable thickness aluminum targets. The SPHIR facility two-stage light-gas gun is capable of routinely launching 5.5 mg nylon impactors to speeds of 5 to 7 km/s. Refinement of legacy SPHIR operation procedures and the investigation of first-stage pressure have improved the velocity performance of the facility, resulting in an increase in average impact velocity of at least 0.57 km/s. Results for the perforation area indicate the considered range of target thicknesses represent multiple regimes describing the non-monotonic scaling of target perforation with decreasing target thickness. The laser side-lighting (LSL) system has been developed to provide ultra-high-speed shadowgraph images of the impact event. This novel optical technique is demonstrated to characterize the propagation velocity and two-dimensional optical density of impact-generated debris clouds. Additionally, a debris capture system is located behind the target during every experiment to provide complementary information regarding the trajectory distribution and penetration depth of individual debris particles. The utilization of a coherent, collimated illumination source in the LSL system facilitates the simultaneous measurement of impact phenomena with near-IR and UV-vis spectrograph systems. Comparison of LSL images to concurrent IR results indicates two distinctly different phenomena. A high-speed, pressure-dependent IR-emitting cloud is observed in experiments to expand at velocities much higher than the debris and ejecta phenomena observed using the LSL system. In double-plate target configurations, this phenomena is observed to interact with the rear-wall several micro-seconds before the subsequent arrival of the debris cloud. Additionally, dimensional analysis presented by Whitham for blast waves is shown to describe the pressure-dependent radial expansion of the observed IR-emitting phenomena. Although this work focuses on a single hypervelocity impact configuration, the diagnostic capabilities and techniques described can be used with a wide variety of impactors, materials, and geometries to investigate any number of engineering and scientific problems.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:hypervelocity impact
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Rosakis, Ares J.
Thesis Committee:
  • Ortiz, Michael (chair)
  • Rosakis, Ares J.
  • Pellegrino, Sergio
  • Ravichandran, Guruswami
Defense Date:21 May 2013
Non-Caltech Author Email:jmmihaly (AT) gmail.com
Funders:
Funding AgencyGrant Number
Department of Energy National Nuclear Security AdministrationDE-FC52-08NA28613
Record Number:CaltechTHESIS:06072013-143355354
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:06072013-143355354
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7869
Collection:CaltechTHESIS
Deposited By: Jonathan Mihaly
Deposited On:16 Jan 2015 17:11
Last Modified:16 Jan 2015 17:11

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