Recent Advances in the Analysis of Spiral Bevel Gears
A review of recent progress for the analysis of spiral bevel gears will be described. The foundation of this work relies on the description of the gear geometry of face-milled spiral bevel gears via the approach developed by Litvin. This methodology was extended by combining the basic gear design data with the manufactured surfaces using a differential geometry approach, and provides the data necessary for assembling three-dimensional finite element models. The finite element models have been utilized to conduct thermal and structural analysis of the gear system. Examples of the methods developed for thermal and structural/contact analysis are presented.
A Method for Determining Spiral-Bevel Gear Tooth Geometry for Finite Element Analysis
Abstract : Spiral bevel gears are currently used in all helicopter power transmission systems. This type of gear is required to turn the corner from a horizontal engine to the vertical rotor shaft. These gears carry large loads and operate at high rotational speeds. Recent research has focused on understanding many aspects of spiral bevel gear operation, including gear geometry, gear dynamics, lubrication, stress analysis and measurement, misalignment, and coordinate measurements, as well as other areas. An analytical method has been developed to determine gear-tooth surface coordinates of face-milled spiral bevel gears. The method uses the basic gear design parameters in conjunction with the kinematical aspects of spiral bevel gear manufacturing machinery. A computer program entitled SURFACE was developed to calculate the surface coordinates and provide three-dimensional model data that can be used for finite element analysis. Development of the modeling method and an example case are presented in this report. This method of analysis could also be applied in gear inspection and near-net-shape gear forging die design.
A study of the local tissue reactions in man to cortisone and compound F. VI. Histopathological studies of the local effect of compound F in normal and pathologic skin of man.
After our previous negative studies (1) of the local effect of cortisone acetate in the skin of man, a year ago, a parallel study of 17-hydroxycorticosterone-21-acetate, Compound F, was outlined. Theoretically, Compound F should be the active steroid. It was so suggested by Rothman (2), that in all probability Compound F and not cortisone would be active locally in the skin of man.