Download or read book Development of an Experimental Methodology for Evaluation of Gear Contact Fatigue Under High power and High temperature Conditions written by Nicholas Leque and published by . This book was released on 2011 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Contact fatigue failures in the form of pitting or micro-pitting have been a perennial problem in power transmission applications. These failures are dictated by a large number of parameters including loading conditions, gear geometry and tooth modifications, kinematics (rolling and sliding velocities), lubricant parameters (viscosity, pressure-viscosity behavior), and material parameters (material type, hardness, case depth, residual stresses). As such, theoretical treatment of contact fatigue failures has been rather challenging, directing the focus to the experimental investigation of the problem. Most of the experimental gear pitting studies to date were limited to low-speed and low-temperature operating conditions. This study aims at developing a methodology for evaluating the contact fatigue lives of gears under high-speed (pitch-line velocities up to 50 m/s), high-stress (contact stresses up to 2 GPa) and high-temperature (oil inlet temperatures up to 150C). Specifications of a test machine concept that meets these requirements are defined and two test machines are designed and procured for this purpose. Gear test specimens that result in pits consistently are developed with the other competing failures (wear, scuffing, tooth breakage), as well as the high vibration conditions, avoided. Preliminary high-speed tests are presented at the end, representing both automotive and aerospace conditions to show that pitting and micro-pitting failures can be produced with the proposed methodology.

Download or read book Development of an Experimental Methodology for Single tooth Bending Fatigue Evaluation of Spur Gears written by Aravind Srinivasan (Gear engineer) and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, a detailed test methodology for evaluating bending fatigue behavior of gears in a single-tooth bending arrangement is developed. A family of load frames customized to conduct single-tooth bending tests are developed. These load frames have capabilities to operate at a wide range of cyclic loads and loading frequencies to collect fatigue data in a repeatable and accelerated manner. A detailed experimental methodology is proposed that includes (i) checks for load distribution, (ii) correction of stress values for dynamic factors as a function of the loading frequency, and (iii) corrections to root stresses, if necessary, based on measured root fillet shapes. The stress prediction method is streamlined and validated through strain gauge measurements. For these predictions, the radius at which the contact line is formed on the test tooth is determined both theoretically and experimentally. Capabilities and effectiveness of the test set-up and the associated methodology are demonstrated through a set of tests to generate stress-life data. The collected data is processed statistically in various ways to compare the resultant L50 lives and confidence limits.

Download or read book NASA Reference Publication written by and published by . This book was released on 1977 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Evaluation of High contact ratio Spur Gears with Profile Modification written by Dennis P. Townsend and published by . This book was released on 1979 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Study on the Scuffing Performance of High power Spur Gears at Elevated Oil Temperatures written by James Walter Brenneman and published by . This book was released on 2013 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this study, a number of spur gear tests were performed under high-power and high-temperature conditions representative of certain aerospace gearing applications. As the first type of tests, long cycle tests of 100 million cycles were performed at set operating speed, load, and temperature conditions. The second type of tests, load-staged scuffing tests, implemented an incrementally increased torque schedule under constant speed and oil temperature conditions. Two different gear tooth surfaces were considered in these tests: hard ground surfaces representative of rough, as machined gear surfaces and chemically polished gear surfaces that were an order of magnitude smoother than the ground surfaces. The primary failure mode of concern was scuffing of the contact surfaces due to temperature build up. The impact of surface roughness amplitudes, contact stress, and oil inlet temperature on scuffing failures were investigated. Effects of ramp up procedures for the speed and torque, as well as the introduction of a break-in test stage were also investigated to show that they are critical to the scuffing performance of gears.

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1992 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Gearing written by John J. Coy and published by . This book was released on 1985 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gearing technology in its modern form has a history of only 100 years. However, the earliest form of gearing can probably be traced back to fourth century B.C. Greece. This publication draws together current gear practice and integrates it with recent advances in the technology. The history of gearing is reviewed briefly in the 'Introduction.' Subsequent sections describe types of gearing and their geometry, processing, and manufacture. Both conventional and more recent methods of determining gear stress and deflections are considered. The subjects of life prediction and lubrication are additions to the literature, not having been treated before. New and more complete methods of power loss prediction as well as an optimum design of spur gear meshes are described. Conventional and new types of power transmission system are presented. (Author).

Download or read book Rolling Contact Fatigue in a Vacuum written by Michael Danyluk and published by Springer. This book was released on 2014-11-03 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with wear and performance testing of thin solid film lubrication and hard coatings in an ultra-high vacuum (UHV), a process which enables rapid accumulation of stress cycles compared with testing in oil at atmospheric pressure. The authors’ lucid and authoritative narrative broadens readers' understanding of the benefits of UHV testing: a cleaner, shorter test is achieved in high vacuum, disturbance rejection by the deposition controller may be optimized for maximum fatigue life of the coating using rolling contact fatigue testing (RCF) in a high vacuum, and RCF testing in UHV conditions enables a faster study of deposition control parameters. In short, Rolling Contact Fatigue in a Vacuum is an indispensable resource for researchers and engineers concerned with thin film deposition, solar flat panel manufacturing, physical vapor deposition, MEMS manufacturing (for lubrication of MEMS), tribology in a range of industries, and automotive and marine wear coatings for engines and transmissions.

Download or read book Japanese Science and Technology 1983 1984 written by United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch and published by . This book was released on 1985 with total page 1080 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Technical Abstract Bulletin written by and published by . This book was released on 1981 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of High Contact Ratio Spur Gears with Profile Modification written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-20 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scoring tests, surface fatigue tests, and single-tooth bending fatigue tests were conducted with four sets of spur gears of standard design and three sets of spur gears of new-tooth-form design. The new-tooth-form and standard gears scored at approximately the same gear bulk temperature of 409 K (277 F). The scoring load for the new-tooth-form gears was 22 percent less than that for the standard gears. The pitting fatigue lives of the standard and new-tooth-form gears were statistically equal for equal Hertz stress, while the surface fatigue life of the nw-tooth-form gears was approximately five times that of the standard gears at the same load. The standard gears failed at a 17 percent higher bending stress than the new-tooth-form gears when stress was calculated by the AGMA method. However, the difference is not statistically significant. The standard gears failed at a tooth load 1.9 times that for the new-tooth-form gears. Towsend, D. P. and Baber, B. B. and Nagy, A. Glenn Research Center NASA-TP-1458, E-9949 RTOP 506-16

Download or read book Experimental and Computational Methods for Strength Analyses of Gears written by Srečko Glodež and published by Cambridge Scholars Publishing. This book was released on 2024-01-24 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gears are machine elements used in most engineering applications, mainly in the automotive and aerospace industries. When designing gear drives, the available standardised procedures are usually used for that purpose. However, the available computational methods are also often applied to obtain the load capacity of gears considering different fatigue design approaches (i.e. the stress-life approach, the strain-life approach and the fatigue crack growth approach). This book consists of five chapters. The first chapter introduces the reader to the fundamental magnitudes of gear drives concerning cylindrical gear pairs, bevel gear pairs, and worm gear pairs. The second chapter explains the theoretical background of the load capacity of gears; surface pitting load capacity and tooth root load capacity are described in detail. The third chapter focuses on the strength analyses of metal gears. Chapters four and five describe the strength analyses of sintered and polymer gears, including some typical practical examples.

Download or read book An Experimental Investigation on the Influence of Tensile Mean Stress on Gear Tooth Bending Fatigue Life written by Zachary Dean Teaford and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, an experimental investigation on the influence of tensile mean stress on gear tooth bending fatigue life is performed. A newly developed single-tooth bending test machine is utilized to perform gear tooth bending fatigue experiments under various loading conditions. A new single-tooth bending test fixture is developed for a chosen test gear. A detailed experimental methodology is presented on dynamic and static strain measurements of the chosen test gear root fillet profile in order to (i) quantify any dynamic loading effects at high loading frequencies, and (ii) validate maximum root stress predictions. Two sets of fatigue tests are performed at load levels of R = 0.05 and R = 0.5 whose results are analyzed statistically to generate L50 and L10 curves for each loading case. Utilizing the L50 stress-life curves, a map of constant life is obtained, showing a straight-line relationships between mean stress and alternating stress. It is shown that an increase in the tensile mean stress reduces the fatigue lives of gear teeth.

Download or read book Lubrication Corrosion and Wear written by United States. National Aeronautics and Space Administration Scientific and Technical Information Division and published by . This book was released on 1965 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metals Abstracts written by and published by . This book was released on 1998 with total page 1042 pages. Available in PDF, EPUB and Kindle. Book excerpt: