astoPlasticLinear_eq17660434141913591234.png" alt="$\dot{\delta_{n}}<0, \delta_{n}\leq\delta_{n}^{res}$" style="width:101px;height:18px;">):</li></ul></div><p><img src="ContactForceN_ElastoPlasticLinear_eq09103056779619198466.png" alt="$$F_{n}^{e} = 0$$" style="width:43px;height:15px;"></p><p>The loading stiffness coefficient <img src="ContactForceN_ElastoPlasticLinear_eq18326203471568379562.png" alt="$K_{n}^{L}$" style="width:20px;height:17px;"> can be computed by 3 different formulas, if its value is not 