The two approaches result in meaningfully different mesh stiffness predictions that persist for wide ranges of applied torque and for gear teeth with tooth surface modifications.

The second approach calculates the local slope of the force–deflection curve about a nominal deflection. The first is a common approach from the literature that calculates the mesh stiffness by dividing the mesh force by the mesh deflection, which we call the average slope method. This work compares spur gear tooth mesh stiffness calculations using two approaches.