To this point, the field of lubrication has been conceptualized using several noncontiguous modes of operation - boundary, fluid-film, and dry and solid lubrication. Engineers and analysts have long had to deal with old evidence that many tribological devices, such as flat surface and centrally pivoted sliders, can act as viable bearings - contradicting basic hydrodynamic theory. Tribology of Interface Layers introduces a new concept wherein disparate modes are shown to actually be particular phases of a tribological continuum spanning a wide array of material lubricants. The author details these phenomena and presents a novel definition of lubricants as intermediate layers. Explores the phenomenon of continuum spectrum as applied to new powder lubrication technology The book illustrates that contrary to previous understanding, the various lubrication modes - from dry to hydrodynamic to powder lubrication - all overlap each other within a tribological spectral continuum. It also elucidates the fact that bearings, seals, dampers, and similar devices using submicron powder lubricants possess quasi-hydrodynamic characteristics akin to conventional fluid films. Similarly, powder films possess quasi-hydrodynamic features that enable them to act as conventional fluid film bearings. The field of tribology has traditionally been presented in terms of disparate regimes, but this method of classification lacked sufficient rigor. This volume explains that characterization and treatment of any one regime may require the simultaneous accounting of several different modalities that are present in a particular mode of operation. Based on experimental and theoretical work, this text shows how the interdependence of powder and hydrodynamic lubrication exemplifies that perpetuity in tribological processes. Author Hooshang Heshmat was on hand for a book signing at the 2010 STLE Meeting. Dr. Heshmat was the 2007 recipient of the Mayo D. Hersey Award, bestowed on an individual in recognition of distinguished and continuous contributions over a substantial period of time to the advancement of the science and engineering of tribology. Check out Dr. Heshmat's wikipedia page.

Continuous flow, mechanical cardiac assist devices rely on a rotating impeller to aid the heart with blood flow. Like any other mechanical system, the rotating components of these devices require some form of load support that is provided by either mechanical or magnetic bearings. The goal of this monograph is to provide an overview of basic principles that are important for design and evaluation of mechanical bearings used in blood pumps, with a primary focus on mechanical bearings used in the second and third generation ventricular assist devices (VADs). A general introduction of some basic principles that are important for design of mechanical bearings is first provided. The basic function of lubricants is described and a brief introduction is provided for surface roughness and the concept of real area of contact. Different lubrication regimes (boundary, mixed and fluid film) are defined. Rheological properties of different types of fluids are described. In the boundary lubrication regime contact lubrication is controlled by the physical and chemical properties of thin films, whereas in the hydrodynamic lubrication regime only physical and rheological properties of the thick fluid films are important. Principles of hydrodynamic lubrication are described and different types of fluid film bearings are discussed. Reynolds Equation which is the fundamental base for fluid film lubrication is discussed and its application to the design of different types of bearings is explored. An example for the design of a blood lubricated thrust bearing is provided. Lubrication of contact bearings is described and some challenging is-sues such as contact damage are briefly introduced. Boundary lubrication with molecular films is described. Fundamental mechanisms of wear and damage formation as well as the use of hard ceramic materials to combat wear are described. Finally examples are provided for current assist devices where blood lubricated contact bearings or hydrodynamic bearings are used.

To this point, the field of lubrication has been conceptualized using several noncontiguous modes of operation - boundary, fluid-film, and dry and solid lubrication. Engineers and analysts have long had to deal with old evidence that many tribological devices, such as flat surface and centrally pivoted sliders, can act as viable bearings - contradicting basic hydrodynamic theory. Tribology of Interface Layers introduces a new concept wherein disparate modes are shown to actually be particular phases of a tribological continuum spanning a wide array of material lubricants. The author details these phenomena and presents a novel definition of lubricants as intermediate layers. Explores the phenomenon of continuum spectrum as applied to new powder lubrication technology The book illustrates that contrary to previous understanding, the various lubrication modes - from dry to hydrodynamic to powder lubrication - all overlap each other within a tribological spectral continuum. It also elucidates the fact that bearings, seals, dampers, and similar devices using submicron powder lubricants possess quasi-hydrodynamic characteristics akin to conventional fluid films. Similarly, powder films possess quasi-hydrodynamic features that enable them to act as conventional fluid film bearings. The field of tribology has traditionally been presented in terms of disparate regimes, but this method of classification lacked sufficient rigor. This volume explains that characterization and treatment of any one regime may require the simultaneous accounting of several different modalities that are present in a particular mode of operation. Based on experimental and theoretical work, this text shows how the interdependence of powder and hydrodynamic lubrication exemplifies that perpetuity in tribological processes. Author Hooshang Heshmat was on hand for a book signing at the 2010 STLE Meeting. Dr. Heshmat was the 2007 recipient of the Mayo D. Hersey Award, bestowed on an individual in recognition of distinguished and continuous contributions over a substantial period of time to the advancement of the science and engineering of tribology. Check out Dr. Heshmat's wikipedia page.