“…However, the experimental observations are not always aligned with the consideration above, particularly in the unsteady environmental conditions such as the oscillations in relative velocity. Therefore, some engineering investigations have revealed that the frictional dynamics can be multi-valued, which means the friction force travels along different paths during the DS and the AS, and forms a non-reversible curve as reported in (Becker and Mahin, 2013;Biswas and Chatterjee, 2014;Neis et al, 2011;Outirba and Hendrick, 2014;Stefański et al, 2006;Wojewoda et al, 2008). The main reason for this phenomenon is the temporal lag between the variations of the friction force and the relative velocity.…”