The complete and accurate solution of the contact the gear contact problem was not unsurmountable, but
problem of three-dimensional gears has been, for the required an approach that combined the strengths of
past several decades, one of the more sought after, the finite element method with those of other
albeit elusive solutions in the engineering community, techniques such as boundary element and surface
Even the arrival of finite element techniques on the integral methods. Concepts from mathematical
scene in the mid seventies failed to produce the programming could be used to advantage in solving
solution to any but the most simple gear contact the contact equations. An innovative approach towards
problems, the formulation of the finite elements themselves
could go a long way towards solving the mesh
The reasons for this are manyfold. When gears are generation and geometric accuracy problems. With the
brought in contact, the width of the contact zone is idea of incorporating the best of these and other
typically an order of magnitude smaller than the other technologies in mind, development of what is now
dimensions of the gears. This gives rise to the need for CAPP (Contact Analysis Program Package) was begun
a very highly refined finite element mesh near the four years ago. It has evolved into a powerful collection
contact zone. But given the fact that the contact zone of computer programs that provide the gear designer
moves over the surface of the gear, one would need a with an insight into the state of stress in gears that has
very highly refined mesh all over the contacting thus far never been possible. Some of the features that
surface. Finite element models refined to this extent CAPP supports are: friction, sub-surface stress
cannot be accommodated on even the largest of today's calculation, stress contours, transmission error, contact
computers. Compounding this difficulty is the fact that pressure distributions and load distribution calculation.
the contact conditions are very sensitive to the
geometry of the contacting surfaces. General purpose Figures 1 to 5 show examples of gear sets for which
finite element models cannot provide the required this process has been successfully used.
level of geometric accuracy. Finally, the difficulties of
generating an optimal three-dimensional mesh that