How to implement the JKR contact model?

[wanqing0421]

How to add cohesion force based on nonlinear contact model. The formula of cohesion force as follow:

F_cohesion = 4.0*sqrt(PI * nSurfaceEnergy * nEquivYoungsMod) * pow(nContactRadius, 1.5);

where nContactRadius=f(nEquivRadius, normalPhysicalOverlap, nSurfaceEnergy).

[hamidrezanorouzi]

It is adding a fraction of elastic force as the cohesion force. In the original formulation the repulsive elastic force has a negative sign in the formula and here it does not have.
contact radius is also another factor that is affected by surfaceEnergy and should be calculated.

I want to transfer this thread to the discussion part where we can discuss this along side the LRF. Please add your query there so we can discuss it in more details.