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dc.contributor.advisorAnanthasuresh, G K
dc.contributor.advisorJoshi, Makarand
dc.contributor.authorAkella, Kiran
dc.date.accessioned2018-06-26T15:08:50Z
dc.date.accessioned2018-07-31T05:48:20Z
dc.date.available2018-06-26T15:08:50Z
dc.date.available2018-07-31T05:48:20Z
dc.date.issued2018-06-26
dc.date.submitted2015
dc.identifier.urihttp://etd.iisc.ac.in/handle/2005/3768
dc.identifier.abstracthttp://etd.iisc.ac.in/static/etd/abstracts/4639/G26967-Abs.pdfen_US
dc.description.abstractPearly layers in seashells, also known as nacreous layers, are reported to be three orders of magnitude tougher than their primary constituent, aragonite. Their high toughness is attributed to a particular structure of alternating layers of natural ceramic and polymer materials. This work tries to emulate it using engineering materials. The thickness, strength, and stiffness of the ceramic layer; the thickness, stiffness, strength, and toughness of the polymer interface layer; and the number of layers are the factors that contribute to different degrees. Furthermore, understanding the relative contribution of different toughening mechanisms in nacre would enable identification of key parameters to design tough engineered ceramics. As a step towards that, in this thesis, layered ceramic beams replicating nacre were studied analytically, computationally, and experimentally. The insights and findings from these studies were then used to develop a new method to make tough layered ceramics mimicking nacre. Subsequently, the use of layered ceramics for armour applications was evaluated. Based on analytical numerical and experimental studies, we observed that the strength of the layers is a key factor to replicate the high toughness of nacre in engineered ceramics. We also demonstrated that, crack deflection and bridging observed in nacre in studies elsewhere, occur due to the high strength of platelets. Based on these findings, the new method developed in this study uses green alumina-based ceramic tapes stacked with screen printed stripes of graphite. During sintering, graphite oxidizes leaving empty channels in the stack. These channels were filled with tough interface materials afterwards. As a result, a ceramic- polymer composite with more than 2-fold increase in toughness was developed. Subsequently, we evaluated layered ceramics for armour applications based on numerical analysis validated with experiments. Consistent to the trends in literature, we observed that layers degrade the resistance to ballistic impact. However, improved energy absorption is demonstrated in layered ceramics. These conflicting dual trends were not presented and quantified in any earlier studies conducted elsewhere. Another new observation not documented earlier is the effect of interface strength. Using an interface material of sufficient strength, penetration resistance of layered ceramics can be improved beyond monolithic ceramics. Using these findings, new layered ceramic armour can be designed that is cost- effective and better performing than monolithic ceramics.en_US
dc.language.isoen_USen_US
dc.relation.ispartofseriesG26967en_US
dc.subjectCeramic Armouren_US
dc.subjectEnmgineered Ceramicsen_US
dc.subjectSeashellsen_US
dc.subjectNatural Ceramicsen_US
dc.subjectLayered Ceramic Beamsen_US
dc.subjectNacreous Seashellsen_US
dc.subjectLayered Ceramicsen_US
dc.subjectCeramic Polymer Compositesen_US
dc.subjectLayered Ceramic Armouren_US
dc.subjectTough Layered Ceramicsen_US
dc.subjectLayered Tough Ceramicsen_US
dc.subjectNacreen_US
dc.subjectCeramic-composite Armouren_US
dc.subject.classificationMechanical Engineeringen_US
dc.titleStudies for Design of Layered Ceramic Armour Inspired by Seashellsen_US
dc.typeThesisen_US
dc.degree.namePhDen_US
dc.degree.levelDoctoralen_US
dc.degree.disciplineFaculty of Engineeringen_US


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