The computer program HeliStat performs finite-element analysis to simulate meshing of helical gears. This program is a logical extension of the program DANST, which applies to spur gears. [DANST was described in "Computing Stresses in Spur Gears (LEW-15420), NASA Tech Briefs, Vol. 19, No. 12 (December 1995), page 73 and "Updated Program for Computing Stresses in Spur Gears (LEW-16575) NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 59.]

HeliStat performs a geometric tooth-contact analysis to determine the lines of tooth contact, and then it performs a three-dimensional linear static analysis to determine tooth-meshing stiffness, tooth deflections under static load, and the static transmission error. The results of the static analysis are available to the user in the form of static transmission error as a function of rotation as well as the peak-to-peak transmission error. Since the transmission error is the major source of dynamic excitation that causes gear vibration and noise, HeliStat can help a gear designer develop quiet gears.

The mathematical model upon which HeliStat is based includes representations of the driving and driven gears, connecting shafts, and supporting bearings. The model also includes provisions for gear-tooth modifications either perpendicular to the lines of contact (cross-modification) or in the profile and longitudinal directions. HeliStat can be used for parametric studies of the effects on the transmission error of helical-gear systems due to torque, tooth stiffness, and gear-tooth modifications.

This program was written by H. H. Lin of the University of Memphis and Fred B. Oswald of Glenn Research Center.

Inquiries concerning rights for the commercial use of this invention should be addressed to

NASA Glenn Research Center
Commercial Technology Office
Attn: Steve Fedor
Mail Stop 4 —8
21000 Brookpark Road
Cleveland
Ohio 44135.

Refer to LEW-16877.

NASA Tech Briefs Magazine

This article first appeared in the November, 2000 issue of NASA Tech Briefs Magazine.

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