ht:18px;"></p><div><ul><li><b>Unloading (before detachment)</b> (<img src="ContactForceN_ElastoPlasticLinear_eq10209806941465127334.png" alt="$\dot{\delta_{n}}<0, \delta_{n}&gt;\delta_{n}^{res}$" style="width:101px;height:18px;">):</li></ul></div><p><img src="ContactForceN_ElastoPlasticLinear_eq01070915712358136388.png" alt="$$F_{n}^{e} = K_{n}^{U} \left ( \delta_{n}-\delta_{n}^{res} \right )$$" style="width:125px;height:18px;"></p><div><ul><li><b>Unloading (after detachment)</b> (<img src="ContactForceN_El