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 Investigation of the Effects of Manufacturing Variations and Materials on Fatigue Crack Detection Methods in Gear Teeth written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-18 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fatigue life of a gear tooth can be thought of as the sum of the number of cycles required to initiate a crack, N(sub i), plus the number of cycles required to propagate the crack to such a length that fracture occurs, N(sub p). The factors that govern crack initiation are thought to be related to localized stress or strain at a point, while propagation of a fatigue crack is a function of the crack tip parameters such as crack shape, stress state, and stress intensity factor. During a test there is no clear transition between initiation and propagation. The mechanisms of initiation and propagation are quite different and modeling them separately produces a higher degree of accuracy, but then the question that continually arises is 'what is a crack?' The total life prediction in a fracture mechanics model presently hinges on the assumption of an initial crack length, and this length can significantly affect the total life prediction. The size of the initial crack is generally taken to be in the range of 0.01 in. to 0.2 in. Several researchers have used various techniques to determine the beginning of the crack propagation stage. Barhorst showed the relationship between dynamic stiffness changes and crack propagation. Acoustic emissions, which are stress waves produced by the sudden movement of stressed materials, have also been successfully used to monitor the growth of cracks in tensile and fatigue specimens. The purpose of this research is to determine whether acoustic emissions can be used to define the beginning of crack propagation in a gear using a single-tooth bending fatigue test. Wheitner, Jeffrey A. and Houser, Donald R. Unspecified Center ACOUSTIC EMISSION; ACOUSTIC MEASUREMENT; BENDING FATIGUE; CRACK PROPAGATION; FATIGUE LIFE; FATIGUE TESTING MACHINES; FRACTURE MECHANICS; GEAR TEETH; NONDESTRUCTIVE TESTS; BEND TESTS; CRACKS; DETECTION; FATIGUE TESTS; STIFFNESS; STRESS WAVES...

Download or read book A Theoretical and Experimental Investigation on Bending Strength and Fatigue Life of Spiral Bevel and Hypoid Gears written by Mohammad Adel Hotait and published by . This book was released on 2011 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: At the end, a multiaxial, crack nucleation fatigue model of tooth bending is proposed; the model accounts for the multiaxial and non-proportional nature of the stress states predicted. Fatigue lives predicted by the proposed model are compared to those estimated by using a conventional uniaxial failure criterion to show that the predicted multiaxial fatigue lives are significantly lower. The fatigue model is also used to quantify the influence of the misalignments as well as certain key cutting tool parameters on the bending fatigue life of the hypoid gear pair.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 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 Dynamic Loads on Gear Teeth written by Earle Buckingham and published by . This book was released on 1931 with total page 86 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 1999 with total page 1014 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Investigation of the Influence of Load Alternation on the Fatigue Strength and Longevity of Components with and Without Stress Concentation Communication Ii written by V. M. Grebenik and published by . This book was released on 1965 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Systematic Analysis of Gear Failures written by Lester E. Alban and published by ASM International. This book was released on 1985-01-01 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explores the detailed steps necessary to determine the causes of failure. First, the physical characteristics of a gear are studied: where the stress points are, from what directions the forces are applied, where the movement of material progresses, and where strain patterns exist. Second, all external conditions and forces are considered. With this background information, a systematic examination is described from beginning to end, the end being a conclusion about the mode and cause of failure.

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 Journal of Tribology written by and published by . This book was released on 1990 with total page 778 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Journal of Engineering for Power written by and published by . This book was released on 1961 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Gear Crack Propagation Path Studies Guidelines for Ultra Safe Design written by and published by . This book was released on 2001 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Design guidelines have been established to prevent catastrophic rim fracture failure modes when considering gear tooth bending fatigue. Analysis was performed using the finite element method with principles of linear elastic fracture mechanics. Crack propagation paths were predicted for a variety of gear tooth and rim configurations. The effects of rim and web thicknesses, initial crack locations, and gear tooth geometry factors such as diametral pitch, number of teeth, pitch radius, and tooth pressure angle were considered. Design maps of tooth/rim fracture modes including effects of gear geometry, applied load, crack size, and material properties were developed. The occurrence of rim fractures significantly increased as the backup ratio (rim thickness divided by tooth height) decreased. The occurrence of rim fractures also increased as the initial crack location was moved down the root of the tooth. Increased rim and web compliance increased the occurrence of rim fractures. For gears with constant pitch radii, coarser-pitch teeth increased the occurrence of tooth fractures over rim fractures. Also, 250 pressure angle teeth had an increased occurrence of tooth fractures over rim fractures when compared to 200 pressure angle teeth. For gears with constant number of teeth or gears with constant diametral pitch, varying size had little or no effect on crack propagation paths.

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1963 with total page 1196 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Investigation of the Combined Effects of Rim Thickness and Pitch Diameter on Spur Gear Tooth Root and Fillet Stresses written by Raymond J. Drago and published by . This book was released on 1981-10-01 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Journal of the Institution of Engineers India written by and published by . This book was released on 1975 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: