Author
G. Halperin
Bio: G. Halperin is an academic researcher from Technion – Israel Institute of Technology. The author has contributed to research in topics: Fretting & Contact area. The author has an hindex of 17, co-authored 20 publications receiving 2177 citations.
Papers
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TL;DR: An analytical model is developed to predict the relation between the opening force and operating conditions in a mechanical seal with laser textured micro surface structure in the form of micropores.
Abstract: An analytical model is developed to predict the relation between the opening force and operating conditions in a mechanical seal with laser textured microsurface structure in the form of micropores The model is valid for any desired shape of the micropores An optimization is performed for spherical shape micropores evenly distributed on one of the mating rings face to maximize the opening force and fluid film stiffness Results of a parametric study are presented showing the effect of the main design parameters on the seal performance Some results of an experimental investigation with water-lubricated seal rings are also shown and compared with the theoretical model Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 26–28, 1998
537 citations
TL;DR: An improved wedge calibration method for quantitative lateral force measurement in atomic force microscopy is presented in this paper, which utilizes a much simpler, commercially available, calibration grating and can be performed at any single specified applied load.
Abstract: An improved wedge calibration method for quantitative lateral force measurement in atomic force microscopy is presented. The improved method differs from the original one in several aspects. It utilizes a much simpler, commercially available, calibration grating and can be performed at any single specified applied load. It enables calibration of all types of probes, both integrated with sharp tips, and colloidal with any radius of curvature up to 2 μm. The improved method also simplifies considerably the calculation of the calibration factor by using flat facets on the calibration grating to cancel out system errors. A scheme for the data processing for on-line calibration of the lateral force is also presented.
387 citations
TL;DR: In this article, the performance of unidirectional and bi-directional partial-LST bearing with a baseline, untextured bearing is compared with that of a baseline bearing in terms of increased clearance and reduced friction.
Abstract: Performance enhancements by laser surface texturing (LST) of parallel-thrust bearings is experimentally investigated. Test results are compared with a theoretical model and good correlation is found over the relevant operating conditions. A comparison of the performance of unidirectional and bi-directional partial-LST bearings with that of a baseline, untextured bearing is presented showing the benefits of LST in terms of increased clearance and reduced friction.
307 citations
TL;DR: In this article, the role of oxide wear debris in fretting wear was studied by allowing them to escape from the interface during sliding by laser surface texturing that forms regular micro-pores topography on the friction surfaces which enables this escape.
298 citations
TL;DR: A new similarity criterion, termed slip index, is introduced, which replaces conventional fretting maps in determining the different fretting regimes as well as the transition from fretting to reciprocal sliding.
Abstract: A new similarity criterion, termed slip index, is introduced. This slip index replaces conventional fretting maps in determining the different fretting regimes as well as the transition from fretting to reciprocal sliding. The slip index is derived from a dimensional analysis of the parameters that govern sliding conditions and provides a unified approach to fretting that is valid for any particular system. The validity of this approach is verified by comparison of fretting data from different test rigs and on different scales. A more accurate definition of fretting is offered based on the present approach.
118 citations
Cited by
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TL;DR: In this article, the authors presented calculations on the global fuel energy consumption used to overcome friction in passenger cars in terms of friction in the engine, transmission, tires, and brakes.
1,198 citations
TL;DR: In this paper, the authors present the state of the art in LST and the potential of this technology in various lubricated applications like mechanical seals, piston rings and thrust bearings.
Abstract: Surface texturing has emerged in the last decade as a viable option of surface engineering resulting in significant improvement in load capacity, wear resistance, friction coefficient etc. of tribological mechanical components. Various techniques can be employed for surface texturing but Laser Surface Texturing (LST) is probably the most advanced so far. LST produces a very large number of micro-dimples on the surface and each of these micro-dimples can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication, a micro-reservoir for lubricant in cases of starved lubrication conditions, or a micro-trap for wear debris in either lubricated or dry sliding. The present paper reviews the current effort being made world wide on surface texturing in general and on laser surface texturing in particular. It presents the state of the art in LST and the potential of this technology in various lubricated applications like mechanical seals, piston rings and thrust bearings. The paper also describes some fundamental on going research around the world with LST.
1,123 citations
TL;DR: Laser Surface Texturing (LST) is probably the most advanced surface texturing technique as mentioned in this paper and it produces a very large number of micro-dimples on the surface and each of these microdimples can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication.
Abstract: Surface texturing has emerged in the last decade as a viable option of surface engineering resulting in significant improvement in load capacity, wear resistance, friction coefficient etc. of tribological mechanical components. Various techniques can be employed for surface texturing but Laser Surface Texturing (LST) is probably the most advanced so far. LST produces a very large number of micro-dimples on the surface and each of these micro- dimples can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication, a micro-reservoir for lubricant in cases of starved lubrication conditions, or a micro-trap for wear debris in either lubricated or dry sliding. The paper reviews the current effort being made world wide on laser surface texturing in particular. It presents the state of the art in LST and the potential of this technology in various lubricated applications like mechanical seals, piston rings, thrust bearings, magnetic recording etc. The paper also describes some fundamental on-going research around the world with LST.
914 citations
TL;DR: In this article, the authors report the advances in the state of the art considering the relationships between the properties of functional surfaces, their applications and the technologies to engineer surfaces, and their applications in many advanced fields, such as: electronics, information technology, energy, optics, tribology, biology and biomimetics.
593 citations
TL;DR: In this paper, the authors provide a comparative summary of different modeling techniques for fluid flow, cavitation and micro-hydrodynamic effects for surface texturing, and provide the key findings.
590 citations