Description
- Abstract:
- Impact cratering is a ubiquitous process affecting planetary surfaces in the solar system. The most probable impact angle is 45°, and ¼ of all impacts in the solar system occur at impact angles less than 30°. Thus, a thorough understanding of oblique impacts, and the effect of impact angle on resultant damage structures and deformation mode, is necessary to truly understand the formation of impact craters on planetary surfaces. The work in this dissertation demonstrates a unique way to approach the study of subsurface damage following oblique hypervelocity impacts. We use impact angle, impact velocity and projectile type to vary conditions within experiments that then allow exploring similar processes at much larger scales. This variation is done both in laboratory experiments and numerical models, which provides new insights into geologic observations made at the surfaces of terrestrial planets. The first chapter examines the importance of shear processes in subsurface damage evolution in experiments, which is revealed by matching numerical models. This study shows that subsurface damage regions grow rapidly with respect to acoustic velocities of the target material, which is likely indicative of shear failure. Matching CTH models confirm this inference. The second chapter continues with detailed examination of deformation mechanisms in planar targets, with a focus on a specific subsurface morphology: failure planes oriented sub-parallel to the impact trajectory that occurs for very oblique impacts. Combining insight garnered from direct comparisons with CTH models, and from textural analysis of the failure planes, we show that they are likely the result of frictional processes during shear deformation following oblique impacts. Chapters three and four examine the effect of layered targets (e.g., sedimentary or ice layers over bedrock) on peak pressure magnitude and deformation in the subsurface. Low-impedance layers with thickness on the order of a projectile diameter are sufficient to significantly reduce shock effects and deformation within the bedrock. Finally, Chapter five extends this study to the case of damage created by oblique impacts into a sphere, and presents the first time-resolved study of damage growth in spherical targets, with applications to failure zones within asteroids.<br/> <br/>
- Notes:
- Thesis (Ph.D. -- Brown University (2012)
Access Conditions
- Rights
- In Copyright
- Restrictions on Use
- Collection is open for research.
Citation
Stickle, Angela M.,
"Epic Failure: A Study of Subsurface Damage Following Oblique Hypervelocity Impacts"
(2012).
Earth, Environmental and Planetary Sciences Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0TH8K0R
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Earth, Environmental and Planetary Sciences Theses and Dissertations
Theses and Dissertations for the Earth, Environmental and Planetary Sciences department....