29214609891401.png" alt="$F_{t}^{e}$" style="width:16px;height:14px;">, provided by a linear spring.</p><p><img src="ContactForceT_Spring_eq09014383034704446111.png" alt="$$\left \{ F_{t} \right \} = -F_{t}^{e} \{-\hat{t}\}$$" style="width:106px;height:18px;"></p><p><img src="ContactForceT_Spring_eq07737106025351550430.png" alt="$$F_{t}^{e} = K_{t} \delta_{t}$$" style="width:63px;height:15px;"></p><p>The tangent stiffness coefficient <img src="ContactForceT_Spring_eq12186984377305326259.png" alt="$K_{t}$" s