Hertz-Mindlin Nassauer-Kuna model
The Hertz-Mindlin Nassauer-Kuna model is a modification of the Hertz-Mindlin model.
The effective radius is calculated using the Nassuaer-Kuna formula:
RNK=Vπd2
Where V is the overlap volume and d is the penetration
depth. The effective radius, RNK is used to determine the equivalent radius,
R* which is substituted into the Hertz-Mindlin formula as follows:Fn=43E*R*1/2d3/2
All forces are multiplied by the correction factor of 0.62/0.752 specified in Nassauer, B., 2013, and is defined as:
fn=(0.620.752)(43)E*√RNK d3/2