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dc.contributor.advisorHooper, Joseph
dc.contributor.authorTan, Yi Ming
dc.dateDec-12
dc.date.accessioned2013-02-15T23:14:03Z
dc.date.available2013-02-15T23:14:03Z
dc.date.issued2012-12
dc.identifier.urihttp://hdl.handle.net/10945/27911
dc.descriptionApproved for public release; distribution is unlimited.en_US
dc.description.abstractWe consider the microstructure and dynamic failure of ice-templated freeze cast alumina materials that are currently being studied for novel warhead cases. The freeze-cast matrix is a porous, cellular structure of overlapping lamellae similar to many biomaterials such as nacre. This lightweight matrix provides a high-toughness shell that can be filled with polymers or combustible reactive materials. Three porosities of alumina freeze-cast structures were studied, and a systematic variation in microstructural properties such as lamellar width and thickness was observed with changing porosity. Dynamic impact tests were performed in a single stage light-gas gun to examine the failure properties of these materials under high strain-rate loading. Nearly complete delamination was observed under impact, along with characteristic cracking across the lamellar width. Average fragment size decreases with increasing porosity, and a theoretical model was developed to explain this behavior. Based on an energy balance between kinetic, strain, and surface energies within a single lamella, we are able to predict the characteristic fragment size using only standard material properties of bulk alumina.en_US
dc.description.urihttp://archive.org/details/microstructurend1094527911
dc.publisherMonterey, California. Naval Postgraduate Schoolen_US
dc.titleMicrostructure and dynamic failure properties of freeze-cast materials for thermobaric warhead casesen_US
dc.typeThesisen_US
dc.contributor.departmentPhysics
dc.subject.authorreactive materialsen_US
dc.subject.authorfragmentationen_US
dc.subject.authorexplosivesen_US
dc.subject.authorwarheadsen_US
dc.subject.authoradvanced materialsen_US
dc.subject.authorfreeze-casten_US
dc.description.serviceCivilian, Defence Science and Technology Agency (Singapore)en_US
etd.thesisdegree.nameMaster of Science In Applied Physicsen_US
etd.thesisdegree.levelMastersen_US
etd.thesisdegree.disciplineApplied Physicsen_US


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