Quasi-static analysis of a face gear under torque

Face gear drives have many advantages over other cross axis transmissions especially in high performance applications. The lack of published design experience and design standards make their design difficult. This is mainly due to the complex geometries and to the lack of practical experience. For these reasons face gears have not been used for long. This work is aimed at investigating the behavior of a face gear transmission considering contact path under load, load sharing and stresses, for an unmodified gear set including shaft misalignment and modification on pinion profile. The investigation is carried out by integrating a 3D CAD system and a FEA code, and by simulating the meshing of pinion and gear sectors with three teeth, using contact elements and an automated contact algorithm. The procedures followed to create the 3D models of teeth in mesh are described and finite element analysis results discussed showing the differences between unmodified, modified and misaligned teeth. Results show the influence of load on theoretically calculated contact paths, contact areas, contact length and load sharing. The differences with respect to the ideal case are sometimes remarkable. Further developments are discussed.© 2003 ASME

Evaluation of the Effect of Misalignment and Profile Modification in Face Gear Drive by a Finite Element Meshing Simulation

This work deals with loaded face gear meshing. In the first part, the software developed is described briefly. This tool can simulate the loaded behavior of face gear meshing and provide results such as the instantaneous pressure distribution along the entire face width of the teeth in contact and loaded transmission error. In the second part of the paper, a comparison between the point or line contact is performed for loaded meshing. Further computations calculate assembling-error sensitivity for the two contact cases. To improve the case of line contact, a method for pinion crowning optimization is presented in the last part. The aim is to obtain the best loaded face gear meshing in order to avoid the sensitivity of the line contact case due to misalignment.Copyright © 2003 by ASME

Analysis and Optimization of the Loaded Meshing of a Face Gear

This paper investigates the geometric properties of the toroidal drive, reveals the meshing characteristics, and develops analytical models of both axial section and normal section of the toroidal tooth profile. Based on coordinate transformation, the meshing function is obtained and leads to the necessary condition of existence of the enveloping surface. The helix and helix lead angle are then proposed for meshing between the sun-worm and planet worm-gears and both undercutting curve and meshing limit curve are introduced. This further leads to the induced normal curvature for evaluating gearing properties and the selection of the best suitable meshing parameters. The geometric analysis and analytical modeling present a tool for design, leading to three tables of numerical results and design parameters. This is then demonstrated in a three-dimensional modeling of both helical sun-worm and stationary internal gear of the toroidal drive.

Geometric Modeling and Meshing Characteristics of the Toroidal Drive

Undercutting characteristics of the curvilinear-tooth gear, cut by a hob cutter performing motion with two independent parameters, are investigated. The tooth contact analysis (TCA) and the surface topology method are applied to study the kinematic errors (KE) and contact ellipses of the curvilinear-tooth gear under different assembly conditions. Several numerical examples are presented to demonstrate the influence of the assembly errors and design parameters of the gear on the KEs and contact ellipses of the gear pair.

Undercutting and Contact Characteristics of Cylindrical Gears With Curvilinear Shaped Teeth Generated by Hobbing

Gears can show significant biaxial stress state at tooth root fillet, due to the way they are loaded and their particular geometry. This biaxial stress state can show a significant variability in principal axes during meshing. Moreover loads may have non predictable components that can be evaluated with the aid of recorded data from complex spectra. In these conditions, commonly adopted approaches for fatigue evaluation may be unsuitable for a reliable fatigue life prediction. This work is aimed at discussing a computer implementation of a fatigue life prediction method suitable for multiaxial stress states and constant amplitude or random loading. For random loading a counting procedure to extract cycles from complex load histories is discussed. This method, proposed by Vidal et al., is based on the r.m.s. value of a damage indicator over all the planes through the point where the fatigue life calculation is made. Miner’s rule is used for the evaluation of the overall damage. The whole fatigue life of the component is evaluated in terms of the numbers of repetitions of the loading block. FEM data are used to evaluate stresses under load. The implementation was validated using test data found in the technical literature. Examples of applications to gears are finally discussed.Copyright © 2003 by ASME

Application of a Multiaxial Fatigue Criterion for the Evaluation of Life of Gears of Complex Geometry

The development of extremely high performance aerospace power transmissions will be a very interesting technological challenge for the next future. In gear design for high power transmission, desirable characteristics, such as low noise emissions, low vibrations, minimum size, minimum maintenance cost, but most of all minimum weight can be obtained through the development of innovative layouts. However, most of the rules based on experimental data, by which common gearns are calculated and verified, are not applicable to transmissions whcih can be defined unconventional in terms of geometry and/or operation conditions (high power, high rotating speed, low weight). In these cases, numerical simulations can be performed bu using FEM codes. The objective of this work is to describe how interated CAD/FEM tools can be employed to develop procedures for the static performance analysis of unconventional gears. In the paper, potential characteristics, limits and capabilities of simulating real system behaviours are discussed.

Leonardo Borgianni

Papers

Evaluation of the Effect of Misalignment and Profile Modification in Face Gear Drive by a Finite Element Meshing Simulation

Application of a Multiaxial Fatigue Criterion for the Evaluation of Life of Gears of Complex Geometry

CAD/FEM procedures for stress analysis in unconventional gear applications

An integrated application of CAD-FEM systems for the analysis of face gear drives

CAD/FEM Analysis of Teeth Contact Stress and Load Share in Face Gears