Hypoid and bevel gears that are widely used in both on and off-highway vehicles have the potential of producing excessive vibrations and noise. The goal of this dissertation research is to establish more effective mathematical model and analytical techniques to characterize the mesh and dynamic behavior, predict vibratory response, and reveal the underlying physics of the hypoid and bevel geared rotor system. The multi-body and multiple-degree-of-freedom (MDOF) dynamic modeling scheme is adopted and the key issues addressed in this dissertation are discussed below.
Firstly, since gear mesh and dynamic characteristics are highly dependent on the torque load, a series of comparative studies and parametric analysis under different nominal torque levels are performed. The purpose is to identify critical factors and applicability of different assumptions for the MDOF hypoid and bevel geared rotor system model. In addition, a dynamic load dependent mesh model is proposed to characterize the potential interaction between dynamics and gear tooth contact.
Secondly, in order to simulate the interaction between the small-displacement gear vibration and the large-angular-displacement driveline torsional dynamics, a coupled multi-body dynamic and vibration model is proposed primarily for nonlinear or transient simulation. This modeling technique possesses the capability of obtaining more realistic response and simulating a wide variety of operating conditions as well as the potential to be applied in the multi-body dynamic analysis of more complete driveline system.
Thirdly, a series of important dynamic and geometric (primarily due to manufacturing error) effects are modeled and analyzed respectively to quantify and/or qualify their influence. For gyroscopic effect as a critical rotor dynamic factor, the study emphasizes their influence on hypoid gear pair vibration as well as the role of rotor inertia distribution on this issue. For assembly errors i.e. misalignments, their influence on spiral bevel gear tooth contact, mesh parameter and dynamic response are examined and differentiated with previous analysis on hypoid gear. The misalignment error sensitivities are identified. For geometric eccentricity i.e. radial runoutness, the appropriate modeling methodology for hypoid gears is proposed and their effect on overall response, nonlinear dynamic behavior and modulation side band response are investigated. For consideration of existence of external excitation, the dynamic interaction between the internal i.e. gear mesh associated excitations and external torque/speed excitations is revealed and related to the different operating conditions. For sliding friction study, a model synthesis approach based on tooth contact analysis is proposed and the varying effective friction coefficient and friction directional parameters are applied to the dynamic analysis. The severity of extra excitation, directionality and load dependence of sliding friction, and their difference in hypoid and spiral bevel gears are presented.
Finally an applied model synthesis, simulation and experimental correlation process for a spiral bevel gear transmission in off-highway application is presented. An effective shaft-bearing support model, and approximate bearing dynamic load and housing surface acceleration computation are introduced. The comparison of dynamic simulation results and experimental measurements provide validation for the proposed analytical models and procedures.