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Advances in engineering analysis software allow engineers more options not only in optimizing gear designs, but also in reducing manufacturing costs and increasing product reliability. A few examples of how we may utilize present day analytical tools to assist in this area are:

Determine dynamic tooth contact stress and fillet strain (also, simulate shock loading);
Consider substitute materials with non-linear properties;
Perform tolerance studies showing how small manufacturing dimensional variations affect operating stress / strain.

View video clip (679 KB) showing von Mises stress in planetary gears rotating under load. Both the mesh and analysis time increments were kept relatively course for this example. More accurate results can be achieved with refinement.

While solid modeling software was still in its early stages of being utilized for mechanical design, Dr. Ackermann had the opportunity to combine the capabilities of this new technology with his previous experience in gear manufacturing. And, in October of 1991, presented a ground breaking paper showing how to model exact gear tooth geometries (as generated by hobbing) at the Intergraph User's Conference in San Antonio, Texas. Representatives from leading gear tool manufacturing and software companies were present.

Though the involute portion of a gear tooth can be modeled graphically using mathematical equations, the geometry of the tooth fillet, being dependent on manufacturing methods, is difficult to model with conventional graphics procedures. In fact, not even all gear software can accurately model this portion of the tooth profile. Yet a proper understanding of the fillet geometry is crucial in avoiding tip interference in meshing gears, as well as in performing accurate stress analyses. Hence it is of vital concern in both design and manufacture.