Dynamic Behavior of Helical Gear Pairs: Model and Experiments

While helical gears are critical components of many power transmission systems, their dynamic behavior has not been studied extensively, perhaps due to their complex vibratory motions and lack of experimental data to guide sound modeling efforts. This study proposes a general dynamic model of a helical gear pair supported by realistic shaft-bearing structures. Aiming at the examination of main assumptions regarding the modeling of helical gears, two versions of the model are constructed, a nonlinear time-varying (NTV) version with gear backlash and time variation of gear mesh stiffness included, and a linear time-invariant (LTI) version, both subject to non-proportional damping. An extensive experimental study is performed covering a large portion of the helical gear design space. Simulations of these experiments indicate that the LTI version of the model with both backlash and mesh stiffness variations ignored compares well with the experiments. The model predictions and measurements collectively show that a helical gear pair acts as a linear system with the loaded motion transmission error as its main excitation. They also indicate that the helical gear motions are three-dimensional, requiring an accurate description of the support structures in the model.