Industry demands for higher power density gearboxes to improveproduct performance require utilization of the load carryingcapability of every inch of available face width. As a result, loaddistributions and the resulting root stresses are of considerableimportance. Current analytical methods include three dimensionalfinite element analysis (FEA) and combinations of Wellauer andSeireg’s moment image method with two dimensional boundary elementanalysis or beam bending formulas. Three dimensional FEA, althoughreliable, is time consuming and of great expense in comparison tothe use of classical techniques and approximations. In helicalgears these approximations give reasonable estimates of root stressdistributions along the face width but lack the accuracy to designto engineering limits.
Based upon finite element and experimental results, adiscrepancy in the approximate methods is the stiffness change inthe normal plane associated with the ends of helical gear teeth.Tooth stiffness is lower at the acute edge, where the normal forceassociated with tooth contact protrudes beyond the transverse edgeof the gearon the back side of the tooth. The opposite resultoccurs at the obtuse edge, where the normal force is not producingbeyond the transverse edge of the tooth.
Analytical and experimental studies for a limited number ofcases have been completed. The experimental results are used toverify the simplified three dimensional FEAparametric study on theeffect of helix angle. The parametric study results, whencompleted, will be used to determine a root stress correctionfactor. The focus of this paper is on the initial parametricresults and experimental studies, with an introduction to possiblecorrection techniques. The correction factors are currently beingresearched and will be the topic of future publications.
- Edition:
- 97
- Published:
- 11/01/1997
- Number of Pages:
- 11
- File Size:
- 0 files
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