ABSTRACT
We take the sum of the equations for the equilibrium of forces and the difference of those for the equilibrium of moments. This way, two quantities become the unknowns of the system:
the difference of the fluctuation between the translations of the two centers, and
the sum of the fluctuations of the rotations about their centers. Because of (5), once evaluated, they give the contact force of the chosen pair AB. A series of sums appears in the system to be solved that are function of the contact stiffness and of the geometry of the neighborhoods of A and B.
