A parametric study on planetary gear dynamics

Thesis Type: Doctorate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Mechanical Engineering, Turkey

Approval Date: 2018




An extended parametric study is performed for Planetary Gear Train (PGTs) dynamics. A purely torsional, non-linear time-varying model is used for the dynamic simulation of PGTs. Time-dependent stiffness functions are calculated by using dedicated contact mechanics software that is specialized in gears. Multi-term Harmonic Balance Method (HBM) is used for the solution of the model. The fundamental modal characteristics of PGTs are explored. The initial parametric studies are performed for the basic dynamic factors in PGTs, namely for different mesh phasing configurations, varying damping levels, different amounts of backlash and different contact ratios for the mating sun-planet and ring-planet meshes. The effect of ring gear elasticity on torsional PGT dynamics is investigated in detail. The direct effects of parameters, which influence the ring gear elasticity, on PGT dynamics are studied. Tooth Profile Modifications (TPMs), which are one of the most effective means of reducing the vibration in gears, are first studied on spur gears. The differences between the ideal TPM designs for different objective functions of minimizing Loaded Static Transmission Error (LSTE) and Dynamic Transmission Error (DTE) are analyzed for gears mounted on rigid and compliant shafts. The positive influence of proper TPM applications on increasing the bending fatigue lives are shown by analyzing the stress cycles on TPM applied spur gear pairs. Next, a comprehensive study is performed on the characteristics of ideal TPMs in PGTs. The dependence of ideal TPM designs on modal characteristics of PGTs is shown. The conditions in which the ideal TPM differs from the TPM configurations that minimize LSTE are explored.