Consequently, the interfacial shear strength will be induced only by C–Cu vdW interaction. If we assumed the common assumption that (*S*) is constant along the embedded length and (*S*) is calculated by dividing maximum (*F*) by interfacial area as in Ref. [9], pull-out force (*F*) will vary with the change of length during pull-out, which contradicts with the previous force-displacement results. Thus, this assumption is inappropriate for a perfect interface. Moreover, according to this assumption, when CNT's length is extremely long (∞), the interfacial shear strength approaches to zero, which is irrational. Therefore, shear strength is only contributed by separation and rejoining of C atoms i.e., (stick-slip) behavior as shown in Fig. 11. The same rationale was used to obtain the interfacial shear strength by Li et al. [30-32]. When an atom of *C* is pulled out of two Cu atoms the oscillatory behavior takes place. Apparently, as seen in Fig. 11, oscillations are attributed to stick-slip behavior. The wave length of this oscillation is (*a*). This process repeats itself every specific displacement (*a*) and takes place along the CNTs. Moreover, (a) denotes the atomic spacing of Cu. The work (*w*) done by this force to overcome vdW interaction is given by the area under the curve