Thesis (Ph.D.)--Lehigh University, 2007. / Adviser: John N. DuPont.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7603. Adviser: Robert S. Averback. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6668. Adviser: Jian-Min Zuo. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (M.S.)--Lehigh University, 2009. / Adviser: Wojciech Z. Misiolek.

High quality silicon nitride ceramics have shown some advantages for rolling element bearing applications. In particular hybrid bearings (silicon nitride rolling elements and steel races) have the ability to withstand high loads, severe environments and high speeds. However, the difficulties of both sintering and machining the material may result in surfacedefects,such as surface ring cracks. It is difficult to detect surface ring cracks during high volume production processes and hence it is crucially important to understand their influence and the fundamental mechanism of the failures they cause. The purpose of this study is to examine the contact fatigue failure modes of silicon nitride rolling elements with surface ring crack defects. In this study, new experimental and computational techniques are developed to measure and model the interaction of the surface with pre-existing crack defects. A rolling contact fatigue test method is devised for positioning the ring crack in the contact path. Rolling contact fatigue tests are conducted using a modified four-ball machine in a hybrid ceramic/steel combination. A three-dimensional boundary element model is used to determine the stress intensity factors and to carry out the crack face contact analysis. Research shows that the RCF life performance of silicon nitride bearing elements is dependent upon the crack location and fatigue spall happens only at a few crack orientations. The spalling fatigue failure is not only influenced by the original ring crack propagation but also strongly influenced by the subsequent crack face contact. Secondary surface cracks play an important role in the forination of a fatigue spall. The crack gap and crack face friction coefficients significantly affect the formation of secondary surface cracks. Numerical calculation results are consistent with the experimental observations. A quantitative three-dimensional boundary element model has been developed, which can be used to determine the geometry of acceptable surfacering cracks.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7621. Adviser: Huseyin Sehitoglu. Includes bibliographical references (leaves 117-130) Available on microfilm from Pro Quest Information and Learning.

Thesis (M.S.)--Worcester Polytechnic Institute. / Includes bibliographical references (leaves 48-51).

Thesis (Ph.D.)--Lehigh University, 2001. / Source: Dissertation Abstracts International, Volume: 61-11, Section: B, page: 6081. Adviser: Arnold R. Marder.

Mineral materials include rocks, minerals, fossils, earths, mineraloids, biogenic skeletal remains and synthetic stones. Each of these classes of material has enjoyed much popularity as supposedly therapeutic medicinal ingredients in the history of pharmacy; many have an unbroken record of use since ancient and classical times. The historical materia medica incorporates minerals that have been made use of in both medical folklore and academic analysis. This thesis presents a body of work which develops examples from each class of mineral material, tries to establish their identities, and explores the evolution of their therapeutic use against the backdrop of changing philosophies in the history of medicine. The most rudimentary use of mineral materials was in a magico-medicinal way as amulets wom for protection against harmful influences which might be expressed in the body as loss of health, and as prophylactics against specific diseases and poisons. Amulets were often worn as pendants, necklaces and rings, or appended to the clothing in some way. The humoral system of Greek medicine saw the health of the body as being a state of balance between the four humours. Humoral imbalance was corrected by, amongst other interventions, the application of medicinal simples or 'Galenicals', which were largely unmodified (other than by trituration) herbal, zoological and mineralogical materials. The choice of simple was determined by the Aristotelian qualities ascribed to them, and their perceived efficacy according to the Doctrine of Signatures. This approach to prescribing practice held sway from classical times until the work of Paracelsus at the beginning of the Scientific Revolution which commended the use of only the active ingredients of a particular simple, separated from the remainder by alchemical means. These iatrochemical preparations permitted dosage standardisation and encouraged a more empirical approach to prescribing practice. The mineral materials most closely examined in this thesis in the context of the evolving materia medica are pumice, gemstones, holed flints, amber, unicom horn, Jews' stones (fossil echinoid spines), Porcupine bezoars, otoliths and synthetic stones. The analyses presented here rely on the study of manuscript, archival, printed and material sources.

Thesis (M.S.)--University of Michigan, 1979.