Catastrophic collisions: Laboratory impact experiments, hydrocode simulations, and the scaling problem.

Persistent Link:
http://hdl.handle.net/10150/186007
Title:
Catastrophic collisions: Laboratory impact experiments, hydrocode simulations, and the scaling problem.
Author:
Ryan, Eileen Valerie Cupta.
Issue Date:
1992
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The catastrophic fragmentation of finite targets is examined both in the laboratory and using a numerical hydrocode. The objective of the empirical study was to gain some insight into the collisional process, specifically, how impact conditions affect collisional outcome. The hydrocode allows us to investigate the fragmentation of large bodies, and to determine how target size influences the impact event. Nearly 150 experiments were performed for this study. Impact velocities ranged from 50-5700 m/s; target material/structure as well as projectile type were varied, and the effect on fragment mass and velocity distributions was documented. Several factors were found to influence the result of a two-body collision: specific energy, momentum, target strength and internal structure, and projectile type. Velocity data showed that average fragment speeds are on the order of 10's of meters per second. Energy partitioned into ejecta kinetic energy is about 1-2% for high velocity collisions and more than 10% for low velocity impacts. Our two-dimensional hydrocode successfully reproduced fragment size distributions and mean ejecta velocities from laboratory impact experiments using basalt, and weak and strong mortar as target materials. It also reproduced size distributions from explosive disruption and applied external pressure experiments which used targets composed of weak mortar and weak basalt grout. Using this hydrocode, we analyzed how target size influences the amount of energy (Q*) required for fracture. Q* was found to decrease with increasing target size in the strength regime; in the gravity regime where incoming stress waves must overcome both material bonds and self-compression, Q* increased with increasing target size. The Q* dependence on target size was found to be much stronger than predicted from scaling law theory.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Dissertations, Academic.; Geophysics.; Astrophysics.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Melosh, H.J.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleCatastrophic collisions: Laboratory impact experiments, hydrocode simulations, and the scaling problem.en_US
dc.creatorRyan, Eileen Valerie Cupta.en_US
dc.contributor.authorRyan, Eileen Valerie Cupta.en_US
dc.date.issued1992en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe catastrophic fragmentation of finite targets is examined both in the laboratory and using a numerical hydrocode. The objective of the empirical study was to gain some insight into the collisional process, specifically, how impact conditions affect collisional outcome. The hydrocode allows us to investigate the fragmentation of large bodies, and to determine how target size influences the impact event. Nearly 150 experiments were performed for this study. Impact velocities ranged from 50-5700 m/s; target material/structure as well as projectile type were varied, and the effect on fragment mass and velocity distributions was documented. Several factors were found to influence the result of a two-body collision: specific energy, momentum, target strength and internal structure, and projectile type. Velocity data showed that average fragment speeds are on the order of 10's of meters per second. Energy partitioned into ejecta kinetic energy is about 1-2% for high velocity collisions and more than 10% for low velocity impacts. Our two-dimensional hydrocode successfully reproduced fragment size distributions and mean ejecta velocities from laboratory impact experiments using basalt, and weak and strong mortar as target materials. It also reproduced size distributions from explosive disruption and applied external pressure experiments which used targets composed of weak mortar and weak basalt grout. Using this hydrocode, we analyzed how target size influences the amount of energy (Q*) required for fracture. Q* was found to decrease with increasing target size in the strength regime; in the gravity regime where incoming stress waves must overcome both material bonds and self-compression, Q* increased with increasing target size. The Q* dependence on target size was found to be much stronger than predicted from scaling law theory.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectDissertations, Academic.en_US
dc.subjectGeophysics.en_US
dc.subjectAstrophysics.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairMelosh, H.J.en_US
dc.contributor.committeememberRichardson, Randallen_US
dc.contributor.committeememberChase, Clementen_US
dc.contributor.committeememberStrom, Roberten_US
dc.contributor.committeememberVickery, Annen_US
dc.identifier.proquest9307670en_US
dc.identifier.oclc713895828en_US
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