Computerized Design, Simulation of Meshing and Stress Analysis of External Helical Gear Drives Based on Critical Control Points

Abstract

Helical gears are widely used in powertrain systems. The computerized design of a new type of non-generated external helical gears based on critical control points at the transverse tooth profile is presented. The entire tooth profile is divided into different parts including the active tooth profile and fillet by control points. Involutes, circular arcs and Hermite curves are defined between two critical control points and smoothly connected with each other at those control points. The parametric equations for the tooth surfaces are derived considering the position of the mentioned control points. The basic design parameters and equations of the geometric sizing are proposed. The contact patterns, variation of the maximum stresses and peak-to-peak level of loaded transmission errors for six cases of design of the proposed new geometry of helical gear drives are studied with two cases of traditional helical gear drives as a reference, including gears with and without micro-geometry modifications. One case of an external helical gear drive designed with a combination of a circular arc and an involute to form the active tooth profile for both the pinion and the gear shows a much lower maximum bending stress and similar lower peak-to-peak level of loaded transmission errors with respect to the other cases of design. The proposed design method of tooth profiles based on critical control points lays the foundation for the topological optimization of helical gear drives.

Static, Dynamic, and High Cycle Fatigue Analysis of Crossed Spherical Gearing for Robotic Arm Ball Joint: A Finite Element Analysis Approach

“…The safety factor in the high cycle fatigue analysis is 5.17 in PEEK material (see Figure 12), considering that the fatigue strength limit is lower than the creep resistance in the static regime since the Marin factors were considered in the fatigue regime. However, stress concentrations exist in both fixed and fatigue analyses at the base of the teeth and tooth contact, as stated in the articles [54]- [60]. At the junction of the crossed spherical gear and the coupling, the teeth of the crossed spherical gear have an essential influence on the fatigue strength of a mechanical component.…”