Hi @peteroznewman,

Since penetration value directly affects the contact pressure and the penetration value is an outcome of normal stiffness value factor:

When should we deviate from the "program controlled" stiffness option? [My current understanding is to always prefer program controlled for most problems unless we see chattering/trouble in convergence]. Most of the theoretical Hertz contact problems when simulated in FEA gave good accuracty with hand calculations with 'program controlled' stiffness but I see alot of literature on the internet suggesting the default 'stiffness factor' of 1 is rarely used and people always override within the range of 0.1 to 1.