41.2.3.1. Normal Force of Tire
The normal force of a road on a tire at the contact patch is generated the direction of z-axial in the contact coordinates.
(41.26)\[{{F}_{z}}=\min \left( 0.0,\text{ }\left\{ \text{ }{{\text{F}}_{\text{zk}}}+{{F}_{zc}}\text{ } \right\} \right)\]
- where,
- \({{F}_{zk}}\) is the normal force due to tire vertical stiffness.\({{F}_{zc}}\) is the normal force due to tire vertical damping.
\({{F}_{zk}}=-K\times \delta\), and
\(K\) : Vertical tire stiffness\(\delta\) : Penetration (tire deflection)
\({{{F}'}_{zc}}=-2.0\times \sqrt{M\times \left| K \right|}\times C\times \dot{\delta }\)
\(M\): Mass of tire\(C\): Vertical damping ratio
\({{F}_{zc}}=\lambda \times {{{F}'}_{zc}}\)
\(\lambda\) is the step function of penetration.
\(Max\delta =0.01*{{r}_{2}}\)
\({{r}_{2}}\) is the carcass radius of toroidal tire.