# The Hertz-Mindlin Nassauer-Kuna model

The effective radius is calculated using the Nassuaer-Kuna formula , where V is the overlap volume and d is the penetration depth. The effective radius, *R _{NK}* is used to determine the equivalent radius,

*R**which is substituted into the Hertz-Mindlin formula as follows:

All forces are multiplied by the correction factor of 0.62/0.752 specified in Based on: Nassauer, B., 2013 and is defined as:

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