Development of an Experimental Procedure to Quantify Dynamic Factors of Spur Gears
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Mechanical and Aerospace Engineering Honors Theses; 2018
Evaluation of bending fatigue failures has traditionally been done experimentally where spur gear specimens are run under different levels of torque to generate stress-life curves for gear designers to use. As life expectancy of any transmission is typically very long, these stress-life curves may also be extended to cover long cycle regimes. As such, collection of gear fatigue data requires significant amount of test time. One way of reducing data collection time is to operate the gears at higher speeds to increase loading frequency. This often results in dynamic effects, which increases tooth loads and dynamic root stresses in the process altering stress-life curves. The dynamic factor (DF), defined as the ratio of the peak values of stress under dynamic and static conditions, must be quantified in order to account for such dynamic effects. In this study, an experimental set-up is developed to measure root fillet strains of a spur gear under both low-speed (quasi-static) and high-speed (dynamic) conditions. A strain-gaged spur gear is loaded in a three-shaft arrangement, and resultant root strains are measured and transferred to a data analysis system. The ratio of the peak values of the stress signal under dynamic and static conditions are computed as the stress-based dynamic factor of the gear pair under these operating conditions. As the gaged gear is operated in an idler arrangement, sets of DF values are established at different levels of torque transmitted.
Academic Major: Mechanical Engineering