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 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 An Investigation of the Influence of Micropitting on the Progression of Gear Surface Pitting written by Eunsung Kim and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, the progression of micropitting and its effect on the fatigue life of a spur gear is investigated through an experimental study. Standard contact durability testing is performed on two test gears and an inspection is done throughout the gear's life cycle. Operating conditions for the test are closely controlled to minimize the effect of applied load, lubrication conditions, shaft rotation speed, and temperature on the micropitting behavior. Gear tooth topography is captured using a gear specific CMM and roughness measurement is obtained using a profilometer. Macroscopic images are also taken to have a record of the physical appearance of the gear flank. Using the experimental data, the severity of surface degradation due to micropitting is quantified by measuring the maximum profile deviation from the initial state. Gear tooth surface topography is used in a load distribution prediction. The change in contact stress distribution and maximum contact stress location are compared to the gear tooth surface topography over the life of the gear to study the effect of micropitting. Contact stress data is then applied to a multi-axial fatigue damage model using the critical plane approach to calculate the fatigue damage parameter. The critical plane is determined by testing which candidate plane produces the maximum shear strain amplitude. Stress and strain components on this critical plane are then applied to the fatigue damage model to calculate the predicted number of cycles to failure, and a damage accumulation rule is employed to predict crack initiation. The maximum accumulated damage location closely aligned with the maximum contact stress location as well as the maximum critical-plane shear strain location. Most importantly, these locations corresponded to the pitting location. Based on the experimental and modelled results, micropitting significantly influences the contact stress distribution that leads to stress concentration, potentially leading to contact fatigue failure such as pitting. The fatigue damage prediction model is somewhat validated through the minimal experimental data further experimental data is needed to develop a method of predicting pitting initiation accurately.

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 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 An Experimental Study of the Impact of Various Tooth Surface Treatments on Spur Gear Pitting Life written by Jeremy Micah Bluestein and published by . This book was released on 2007 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this study, the influence of various engineered surface treatments on the contact fatigue behavior of spur gear pairs was investigated, focusing on pitting life. A number of standard gear durability test machines were furbished and sets of specially designed spur gear test specimens were procured to execute a test matrix that includes gears having various surface treatments. Typical hobbed-shaved surfaces were considered to represent the baseline surface treatment and their pitting lives were compared to lives of gears having (i) chemically polished, (ii) shot-peened and plastic honed, and (iii) chemically polished and CrN coated surfaces. Pitting life of each variation was quantified at several stress levels by using a set of predetermined failure criteria, and test and inspection procedures. The data for each variation was processed statistically and compared to data from other surface variations. The results indicate that chemically polishing increases the pitting life of spur gears nearly three times over the life of the baseline hobbed-shaved gears. It was also observed that the shot-peened and plastic honed gears did not deliver any tangible pitting life improvements over the baseline conditions. Finally, a slight increase in pitting life was observed over chemically polished gears with the application of the CrN coating.

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 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 Analysis of the Effects of Surface Pitting and Wear on the Vibrations of a Gear Transmission System written by and published by . This book was released on 1994 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dynamic Modelling and Fault Feature Analysis of Gear Tooth Pitting and Spalling written by Yang Luo and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fault feature analysis of gear tooth spall plays a vital role in gear fault diagnosis. Knowing the characteristic of fault features and their evolution as a gear tooth fault progresses is key to fault severity assessment. This thesis provides a comprehensive (both theoretical and experimental) analysis of the fault vibration features of a gear transmission with progressive localized gear tooth pitting and spalling. A dynamic model of a one-stage spur gear transmission is proposed to analyze the vibration behavior of a gear transmission with tooth fault. The proposed dynamic model considers the effects of Time Varying Mesh Stiffness (TVMS), tooth surface roughness changes and geometric deviations due to pitting and spalling, and also incorporates a time-varying load sharing ratio, as well as dynamic tooth contact friction forces, friction moments and dynamic mesh damping ratios. The gear dynamical model is validated by comparison with responses obtained from an experimental test rig under different load and fault conditions. In addition, several methods are proposed for the evaluation of the TVMS of a gear pair with tooth spall(s) with curved bottom and irregular shapes, which fills the current research gap on modelling tooth spalls with irregular shapes and randomly distribution conditions. Experiments are conducted and the fault vibration features and their evolution as the tooth fault progresses are analyzed. Based on feature analysis, a new health indicator is proposed to detect progressive localized tooth spall.

Download or read book An Experimental Investigation of the Impact of Engineered Surface Processes on Efficiency of Spur Gears written by Kreteeka Chaudhury and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study was conducted to evaluate the effect of surface finish on spur gear power losses under jet lubrication. Four different surface finish combinations were tested: (i) hard ground surface pair, (ii) chemically polished surface pair, (iii) super honed surface pair and (iv) hard ground against chemically polished surface pair. The test was conducted at 432 different operating condition combinations of speed, torque, lubricant type and inlet temperature. An FZG back-to-back set up was used to conduct the test. Surface roughness inspections were carried out at regular intervals to monitor any changes in surface roughness characteristics. The measured power losses were resolved into spin (load independent) and mechanical (load dependent) power losses. The relation between both losses and various operating conditions were explored. As expected, spin power loss did not vary with variation in surface finish. Mechanical power loss increased with increase in speed and torque. Various surface roughness and operating parameters such as BAC curves and lambda ratio were calculated for each surface finish combination to study their correlation to power losses measured. For smoother surfaces, an increase in temperature decreased power loss as the viscosity of the lubricant decreased and hence rolling friction losses dominating the mechanical power loss decreased. However, for rougher surfaces sliding friction losses seemed to be dominant due to high amounts of asperity contact. Thus, more cases of higher power loss at high temperatures were observed for rougher surfaces.

Download or read book The Effect of Surface Roughness on the Micro elastohydrodynamic Lubrication and Scuffing Performance of Aerospace Gear Tooth Contracts written by M.J. Patching and published by . This book was released on 1994 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Predictive Procedure for Wear Pitting and Scoring of Gears Based on Combined Thermal and Mechanical Stresses written by Joselito D. Cariaga and published by . This book was released on 1997 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Surface Roughness on the Micro elastohydrodynamic Lubriation and Scuffing Performance of Aerospace Gear Tooth Contacts written by Michael John Patching and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Predicted Effect of Dynamic Load on Pitting Fatigue Life for Low contact ratio Spur Gears written by David G. Lewicki and published by . This book was released on 1986 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: How dynamic load affects the surface pitting fatigue life of external spur gears was predicted by using NASA computer program TELSGE. Parametric studies were performed over a range of various gear parameters modeling low-contact-ratio involute spur gears. In general, gear life predictions based on dynamic loads differed significantly from those based on static loads, with the predictions being strongly influenced by the maximum dynamic load during contact. Gear mesh operating speed strongly affected predicted dynamic load and life. Meshes operating at a resonant speed or one-half the resonant speed had significantly shorter lives. Dynamic life factors for gear surface pitting fatigue were developed on the basis of the parametric studies. In general, meshes with higher contact ratios had higher dynamic life factors than meshes with lower contact ratios. A design chart was developed for hand calculations of dynamic life factors. (Author).

Download or read book The Influence of Lubrication on the Onset of Surface Pitting in Machinable Hardness Gear Teeth written by C. Massey and published by . This book was released on 1991-10 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Gear Materials Properties and Manufacture written by Joseph R. Davis and published by ASM International. This book was released on 2005 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: All of the critical technical aspects of gear materials technology are addressed in this new reference work. Gear Materials, Properties, and Manufacture is intended for gear metallurgists and materials specialists, manufacturing engineers, lubrication technologists, and analysts concerned with gear failures who seek a better understanding of gear performance and gear life. This volume complements other gear texts that emphasize the design, geometry, and theory of gears. The coverage begins with an overview of the various types of gears used, important gear terminology, applied stresses and strength requirements associated with gears, and lubrication and wear. This is followed by in-depth treatment of metallic (ferrous and nonferrous alloys) and plastic gear materials. Emphasis is on the properties of carburized steels, the material of choice for high-performance power transmission gearing.