Download or read book The Influence of Roughness on Gear Surface Fatigue written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gear working surfaces are subjected to repeated rolling and sliding contacts, and often designs require loads sufficient to cause eventual fatigue of the surface. This research provides experimental data and analytical tools to further the understanding of the causal relationship of gear surface roughness to surface fatigue. The research included evaluations and developments of statistical tools for gear fatigue data, experimental evaluation of the surface fatigue lives of superfinished gears with a near-mirror quality, and evaluations of the experiments by analytical methods and surface inspections. Alternative statistical methods were evaluated using Monte Carlo studies leading to a final recommendation to describe gear fatigue data using a Weibull distribution, maximum likelihood estimates of shape and scale parameters, and a presumed zero-valued location parameter. A new method was developed for comparing two datasets by extending the current methods of likelihood-ratio based statistics. The surface fatigue lives of superfinished gears were evaluated by carefully controlled experiments, and it is shown conclusively that superfinishing of gears can provide for significantly greater lives relative to ground gears. The measured life improvement was approximately a factor of five. To assist with application of this finding to products, the experimental condition was evaluated. The fatigue life results were expressed in terms of specific film thickness and shown to be consistent with bearing data. Elastohydrodynamic and stress analyses were completed to relate the stress condition to fatigue. Smooth-surface models do not adequately explain the improved fatigue lives. Based on analyses using a rough surface model, it is concluded that the improved fatigue lives of superfinished gears is due to a reduced rate of near-surface micropitting fatigue processes, not due to any reduced rate of spalling (sub-surface) fatigue processes. To complete the evaluations, surface insp

Download or read book The Influence of Roughness on Gear Surface Fatigue written by Timothy L. Krantz and published by . This book was released on 2002 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Fatigue Lives of Case Carburized Gears With an Improved Surface Finish written by and published by . This book was released on 2000 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous research provides qualitative evidence that an improved surface finish can increase the surface fatigue lives of gears. To quantify the influence of surface roughness on life, a set of AISI 9310 steel gears was provided with a near-mirror finish by superfinishing. The effects of the superfinishing on the quality of the gear tooth surfaces were determined using data from metrology, profilometry, and interferometric microscope inspections. The superfinishing reduced the roughness average by about a factor of 5. The superfinished gears were subjected to surface fatigue testing at 1.71-GPa (248-ksi) Hertz contact stress, and the data were compared with the NASA Glenn gear fatigue data base. The lives of gears with superfinished teeth were about four times greater compared with the lives of gears with ground teeth but with otherwise similar quality.

Download or read book The Influence of Roughness on Gear Surface Fatigue written by Timothy Krantz and published by BiblioGov. This book was released on 2013-07 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NASA Technical Reports Server (NTRS) houses half a million publications that are a valuable means of information to researchers, teachers, students, and the general public. These documents are all aerospace related with much scientific and technical information created or funded by NASA. Some types of documents include conference papers, research reports, meeting papers, journal articles and more. This is one of those documents.

Download or read book The Surface Fatigue Of Gear Steels Effects Of Surface Roughness written by Dragen O. Johari and published by . This book was released on 1969 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Correlation of Specific Film Thickness and Gear Pitting Life written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-13 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of the lubrication regime on gear performance has been recognized, qualitatively, for decades. Often the lubrication regime is characterized by the specific film thickness defined as the ratio of lubricant film thickness to the composite surface roughness. It can be difficult to combine results of studies to create a cohesive and comprehensive dataset. In this work gear surface fatigue lives for a wide range of specific film values were studied using tests done with common rigs, speeds, lubricant temperatures, and test procedures. This study includes previously reported data, results of an additional 50 tests, and detailed information from lab notes and tested gears. The dataset comprised 258 tests covering specific film values (0.47 to 5.2). The experimentally determined surface fatigue lives, quantified as 10-percent life estimates, ranged from 8.7 to 86.8 million cycles. The trend is one of increasing life for increasing specific film. The trend is nonlinear. The observed trends were found to be in good agreement with data and recommended practice for gears and bearings. The results obtained will perhaps allow for the specific film parameter to be used with more confidence and precision to assess gear surface fatigue for purpose of design, rating, and technology development. Krantz, Timothy L. Glenn Research Center WBS 380046.02.03.02.02.01

Download or read book Finite Element Based Surface Fatigue Estimation in Involute Spur Gear written by Solomon Tekeste and published by LAP Lambert Academic Publishing. This book was released on 2012 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pitting and scoring is a phenomenon in which small particles are removed from the surface of the tooth due to the high contact stresses that are present between mating teeth. After the investigation of shot pinning to increase the tooth bending strength in gears, surface durability, in the form of macro and micro-pitting, is now considered the dominant restriction on gear life and performance. In this book a method is develop to study surface fatigue in involute spur gears using finite element analysis. In achieving this two-dimensional & three-dimensional equivalent contacting cylinders & three-dimensional model of involute spur gear is used. The modeling is done using finite element computer package, ANSYS & solid modeling software, CATIA. In this book effect of loading condition and material types in contact stress in gears, estimation of surface fatigue in rolling-sliding contact condition in spur gear, effect of initial surface roughness on surface fatigue is studied. The results obtained are compared with analytical method.

Download or read book Influence of Surface Roughness on Gear Pitting Behavior written by T. C. Jao and published by . This book was released on 2004 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Tribology and Surface Engineering written by Aleksander Lisiecki and published by MDPI. This book was released on 2020-01-15 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book covers very important issues, not only scientific in nature but, ultimately, for industry and the economy. Wear and deterioration of surface properties during operation is a natural and unavoidable phenomenon. However, minimizing the degree of wear is of great importance for the entire economy, as illustrated by the example of the US economy, for which the loss of natural resources as a direct cause of friction and wear exceeds 6% of the Gross National Product. This book showcases the valuable knowledge revealed from both theoretical and practical research results in the field of advanced technologies of coatings and surface modification, as well as wear and tribological characteristics of advanced materials and surface layers. Therefore, it is hoped that this book will be a valuable resource and helpful tool for scientists, engineers, and students in the field of surface engineering, materials science, and manufacturing engineering.

Download or read book An Experimental Investigation of the Influence of the Lubricant Viscosity and Additives on Gear Wear written by Timothy L. Krantz and published by BiblioGov. This book was released on 2013-07 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The influence of lubricant viscosity and additives on the average wear rate of spur gear pairs was investigated experimentally. The gear specimens of a comprehensive gear durability test program that made use of seven lubricants covering a range of viscosities were examined to measure gear tooth wear. The measured wear was related to the as-manufactured surface roughness, the elastohydrodynamic film thickness, and the experimentally determined contact fatigue lives of the same specimens. In general, the wear rate was found to be inversely proportional to the viscosity of the lubricant and to the lambda ratio (also sometimes called the specific film thickness). The data also show an exponential trend between the average wear rates and the surface fatigue lives. Lubricants with similar viscosities but differing additives and compositions had somewhat differing gear surface fatigue lives and wear rates.

Download or read book The Influence of Surface Roughness on Fatigue Endurance Strength written by Jonathan R. Hembree and published by . This book was released on 2013 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Characteristics of Surface Roughness Important to Gear and Rolling Bearing Problems written by R. S. Sayles and published by . This book was released on 1985 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The role of surface roughness in rolling and rolling and sliding contacts is examined. Examples of the influence of roughness are drawn from helicopter transmission and rolling bearing research at Imperial College, London. The important influence of geometry and roughness in tribological problems has been accepted for many years but only limited progress has been made in understanding the exact mechanisms involved and incorporating this knowledge into surface finishing processes designed to improve performance. This papers presents an approach to surface topography measurement and analysis which allows many of these problems to be examined in great detail. Examples of the approach are presented for several problems to be examined in great detail. Examples of the approach are presented for several tribological problems including dimensional tolerance, rolling contact noise, and fatigue life, and in each case the character of the important range and size of surface roughness features is identified in terms of its influence on the specific problem under examination.

Download or read book An Experimental Investigation of the Influence of the Lubricant Viscosity and Additives on Gear Wear written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-24 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The influence of lubricant viscosity and additives on the average wear rate of spur gear pairs was investigated experimentally. The gear specimens of a comprehensive gear durability test program that made use of seven lubricants covering a range of viscosities were examined to measure gear tooth wear. The measured wear was related to the as-manufactured surface roughness, the elastohydrodynamic film thickness, and the experimentally determined contact fatigue lives of the same specimens. In general, the wear rate was found to be inversely proportional to the viscosity of the lubricant and to the lambda ratio (also sometimes called the specific film thickness). The data also show an exponential trend between the average wear rates and the surface fatigue lives. Lubricants with similar viscosities but differing additives and compositions had somewhat differing gear surface fatigue lives and wear rates. Krantz, Timothy L. and Kahraman, Ahmet Glenn Research Center NASA/TM-2005-213956, ARL-TR-3126, E-15272

Download or read book Influence of Shot Peening and Surface Finish on the Fatigue of Gears written by Jishan Zhang and published by . This book was released on 2005 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Failure Atlas for Hertz Contact Machine Elements written by T. E. Tallian and published by American Society of Mechanical Engineers. This book was released on 1999 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: New edition of a photographic failure documentation relating to Hertz machine elements. Part I (general information), comprises a review of background, failure classification codes, and appearance classification tables. Part II (plates), the main body of the book, is composed of a series of bandw image pages, each of which illustrates one major failure class. An introduction to each chapter describes the definition, failure process, appearance, causes, and effect of the failure mode(s) covered. Concludes with a section of color illustrations. Annotation copyrighted by Book News, Inc., Portland, OR

Download or read book Finishing of Conical Gears by Pulsed Electrochemical Honing written by Neelesh K Jain and published by Cambridge Scholars Publishing. This book was released on 2019-06-04 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book sheds light on the development of Pulsed-Electrochemical Honing (PECH), a unique hybrid finishing process, which has capabilities of finishing intricate shaped components (especially gears). The text covers the fundamentals of the process, and details all parameters of PECH in the finishing of straight bevel gears. It discusses all important aspects of electrochemical honing, and details recent developments in tools, technologies, controls and operations.

Download or read book International Gear Conference 2014 26th 28th August 2014 Lyon written by Philippe Velex and published by Chandos Publishing. This book was released on 2014-09-18 with total page 1225 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents papers from the International Gear Conference 2014, held in Lyon, 26th-28th August 2014. Mechanical transmission components such as gears, rolling element bearings, CVTs, belts and chains are present in every industrial sector and over recent years, increasing competitive pressure and environmental concerns have provided an impetus for cleaner, more efficient and quieter units. Moreover, the emergence of relatively new applications such as wind turbines, hybrid transmissions and jet engines has led to even more severe constraints. The main objective of this conference is to provide a forum for the most recent advances, addressing the challenges in modern mechanical transmissions. The conference proceedings address all aspects of gear and power transmission technology and range of applications (aerospace, automotive, wind turbine, and others) including topical issues such as power losses and efficiency, gear vibrations and noise, lubrication, contact failures, tribo-dynamics and nano transmissions. - A truly international contribution with more than 120 papers from all over the world - A judicious balance between fundamental research and industrial concerns - Participation of the most respected international experts in the field of gearing - A wide range of applications in terms of size, power, speed, and industrial sector