A study of the bending stresses in a Wildhaber-Novikov gear set

In this investigation an attempt is made to study the bending stress concentration factor in the Wildhaber Novikov system of gearing. This is done by testing a set of commercially available gears (three dimensional) and a plane model representing the same system (two dimensional study). An equation was developed for the Lewis Factor in this system, based on all the allowable design variables. The objectives of the study also included relating the two dimensional and three dimensional results in a meaningful manner to see if a two dimensional study can produce useful results in a system which employs helical action to transmit motion.;The results of this experiment indicate that the two dimensional bending stress concentration factors can be used to predict the average stress in the three dimensional case. This average stress is independent of where the contact point is along the tooth length (for single tooth contact). It is also necessary to define a stress distribution factor which is the ratio of the maximum stress along the tooth length to the average stress. This stress distribution factor was found to remain constant, for the ratio of axial overlap studied, in the central region of tooth contact. Reasonable comparison was found with previous investigators in terms of the stress concentration factor; however large differences were found in terms of the stress distribution factor.;It is possible to use the photostress technique to determine the locations of maximum bending stress at the end, of the tooth. These points agree with those obtained from the two dimensional model. The combination of the three analysis techniques leads to a comprehensive study of a helical gearing system.;The study of the metal gears involved the use of both photostress on the ends of the teeth and strain gages along their length. The two dimensional study was carried out using a photoelastic approach.