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Fatigue Life

TECHNICAL ARTICLES | 2025-02-27

Very High Cycle Fatigue Testing of AMS 6308 Steel

In this paper, ultrasonic fatigue testing results for “core hardened” AMS 6308 gear steel are presented. AMS 6308 is a gear and bearing steel with high tempering resistance and high hot hardness case targeted to high temperature applications

TECHNICAL ARTICLES | 2022-06-27

Design and Simulation of a Back-to-Back Test Rig for Ultra High Cycle Fatigue Testing of Gears Under Fully Reversed Load

Aircraft engines can be made more efficient by integrating planetary gears. In such an application, the planetary gears experience very high load cycles under fully reversed bending loads. Pulsator test rigs, which nowadays offer the possibility to perform UHCF investigations, can only be used for purely pulsating loading of gears. Therefore, for the investigation of the UHCF tooth root load carrying capacity under fully reversed bending load, a back-to-back test rig is required. Back-to-back test rigs usually have speeds of n = 3,000 rpm, which makes investigations in the UHCF range take a very long time. Therefore, a high-speed back-to-back test rig was developed.

INDUSTRY NEWS | 2021-02-22

Fatigue Strength and Service Calculation of Gears

Bevel gear design is well-established. Flank geometry optimization is used worldwide to ensure satisfactory low-noise emis...

GEAR TALK WITH CHUCK | 2018-10-23

Appropriate Improvements

“Resto moding” a gearbox is not t...

TECHNICAL ARTICLES | 2018-05-01

Prediction of Dynamic Factors for Helical Gears in a High-Speed Multibody Gearbox System

Accurate prediction of gear dynamic factors (also known as Kv factors) is necessary to be able to predict the fatigue life of gears. Standards-based calculations of gear dynamic factors have some limitations. In this paper we use a multibody dynamic model, with all 6 degrees of freedom (DOF) of a high-speed gearbox to calculate gear dynamic factors. The findings from this paper will help engineers to understand numerous factors that influence the prediction of dynamic factors and will help them to design more reliable gears.

GEAR TALK WITH CHUCK | 2017-12-14

Engineering Safety (Part Two)

To an engineer there are no accidents, only unanticipated consequences of situations that need to be better understood. We even have a rule about i...

INDUSTRY NEWS | 2014-05-01

Industry News

The complete Industry News section from the May 2014 issue of Gear Technology.

TECHNICAL ARTICLES | 2009-08-01

Effects of Axle Deflection and Tooth Flank Modification on Hypoid Gear Stress Distribution and Contact Fatigue Life

As is well known in involute gearing, “perfect” involute gears never work perfectly in the real world. Flank modifications are often made to overcome the influences of errors coming from manufacturing and assembly processes as well as deflections of the system. The same discipline applies to hypoid gears.

VOICES | 1993-01-01

Our Readers Discuss Gear Rattle, Gear Books, and Gear Tech

Investigation of Gear Rattle Phenomena The article by Messrs. Rust, Brandl and Thien was very interesting in its description of the problem and of some of the interactions which occur.

TECHNICAL ARTICLES | 1990-01-01

Surface Fatigue Life on CBN and Vitreous Ground Carburized and Hardened AISA 9310 Spur Gears

Spur gear surface endurance tests were conducted to investigate CBN ground AISI 9310 spur gears for use in aircraft applications, to determine their endurance characteristics and to compare the results with the endurance of standard vitreous ground AISI 9310 spur gears. Tests were conducted with VIM-VAR AISI 9210 carburized and hardened gears that were finish ground with either CBN or vitreous grinding methods. Test conditions were an inlet oil temperature of 320 K (116 degree F), an outlet oil temperature of 350 K (170 degree F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. The CBN ground gears exhibited a surface fatigue life that was slightly better than the vitreous ground gears. The subsurface residual stress of the CBN ground gears was approximately the same as that for the standard vitreous ground gears for the CBN grinding method used.

INDUSTRY NEWS | 1986-01-01

The Process of Gear Shaving

Gear shaving is a free-cutting gear finishing operation which removes small amounts of metal from the working surfaces of the gear teeth. Its purpose is to correct errors in index, helical angle, tooth profile and eccentricity. The process can also improve tooth surface finish and eliminate, by crowned tooth forms, the danger of tooth end load concentrations in service. Shaving provides for form modifications that reduce gear noise. These modifications can also increase the gear's load carrying capacity, its factor of safety and its service life.

TECHNICAL ARTICLES | 1984-08-01

Maximum Surface Temperature of the Thermoplastic Gear in a Non-Lubricated Plastic-Steel Gear Pair

One of the major problems of plastic gear design is the knowledge of their running temperature. Of special interest is the bulk temperature of the tooth to predict the fatigue life, and the peak temperature on the surface of the tooth to avert surface failure. This paper presents the results of an experimental method that uses an infrared radiometer to measure the temperature variation along the profile of a plastic gear tooth in operation. Measurements are made on 5.08, 3.17, 2.54, 2.12 mm module hob cut gears made from nylon 6-6, acetal and UHMWPE (Ultra High Molecular Weight Polyethylene). All the tests are made on a four square testing rig with thermoplastic/steel gear pairs where the plastic gear is the driver. Maximum temperature prediction curves obtained through statistical analysis of the results are presented and compared to data available from literature.