Nonlinear dynamics of spiral bevel gear pair

Önal, Birkan
Nonlinear dynamics of a generic spiral bevel gear pair used in high speed, high power gearboxes is studied in this thesis. Different tooth ease-off topographies are generated based on real machine settings. Tooth micro geometries are established in order to obtain profile crowning, lengthwise crowning and flank twist topographies. Details of macro and micro geometry and corresponding real machine settings are given in this study. Path of contact, contact stress, directional rotation radius, load share, unloaded and loaded static translational transmission error, and mesh stiffness are presented for drive and coast sides of gear tooth. Loaded analyses are conducted at 100Nm, 200Nm and 400Nm torque loads. These ease-off topographies are compared for many advantages on the stability of path of contact, lowest contact stress, lowest unloaded and loaded transmission errors, and highest mesh stiffness. The accumulated results are used in nonlinear dynamic analysis of a spiral bevel gear pair. Dynamic model includes gear backlash in the form of clearance-type displacement function, time variation of mesh parameters, which are gear mesh stiffness, directional rotation radius and mesh damping. The mesh parameters are also asymmetric due to difference between drive and coast sides of gear tooth. The system is reduced to a single-degree-of-freedom definite model by using the relative gear mesh displacement as the generalized coordinate. The equation of motion is solved for periodic steady-state response by using Harmonic Balance Method. A set of parametric studies are performed to determine the effects of different tooth flank modifications on dynamic response of a helicopter transmission drive system.