Intermittent stick-slip dynamics during the peeling of an adhesive tape from a roller

We study experimentally the fracture dynamics during the peeling at a constant velocity of a roller adhesive tape mounted on a freely rotating pulley. Thanks to a high speed camera, we measure, in an intermediate range of peeling velocities, high frequency oscillations between phases of slow and rapid propagation of the peeling fracture. This so-called stick-slip regime is well known as the consequence of a decreasing fracture energy of the adhesive in a certain range of peeling velocity coupled to the elasticity of the peeled tape. Simultaneously with stick slip, we observe low frequency oscillations of the adhesive roller angular velocity which are the consequence of a pendular instability of the roller submitted to the peeling force. The stick-slip dynamics is shown to become intermittent due to these slow pendular oscillations which produce a quasistatic oscillation of the peeling angle while keeping constant the peeling fracture velocity (averaged over each stick-slip cycle). The observed correlation between the mean peeling angle and the stick-slip amplitude questions the validity of the usually admitted independence with the peeling angle of the fracture energy of adhesives.

Figure 1

Schematic view of the experimental setup. The angles $\alpha$ and $\beta$ are oriented clockwise and counterclockwise, respectively. Roller diameter: 40 mm $<2R<58$ mm; roller and tape width: $b=19$ mm; tape thickness: $e=58\mu$m.

Figure 2

Peeling point velocity $v_p\left(t\right)$ in the roller reference frame for an experiment performed at $V=0.90$ m s${}^{-1}$. Triangles and squares, respectively, show the averaged stick $v_{\mathrm{stick}}$ and slip $v_{\mathrm{slip}}$ velocities for each stick-slip cycle. The horizontal straight line shows the imposed peeling velocity $V$.

Figure 3

(a) Peeling point velocity $v_p$ in the roller reference frame as a function of time for an experiment performed at $V=0.90$ m s${}^{-1}$. The top and bottom continuous lines, respectively, trace the slip and stick local mean velocities. The horizontal straight line shows the average peeling velocity $V$. (b) shows the corresponding instantaneous peeling point angular position $\alpha$ as a function of time.

Figure 4

(a) Peeling point velocity $v_p$ in the roller reference frame and (b) angular positions $\alpha \left(t\right)$ and $-\delta \beta \left(t\right)\equiv Vt/R-\beta \left(t\right)$ as functions of time for an experiment performed at $V=2.24$ m s${}^{-1}$. Same layout as in Fig. 3.

Figure 5

Mean angle $\alpha$ (squares) during each experiment and the corresponding standard deviation of its oscillations as error bars. Circles show the maximum and minimum angle $\alpha$ reached during each experiment.

Figure 6

(a) Average slip (squares) and stick (circles) velocities and maximum slip (up triangle) and minimum stick (down triangle) velocities and (b) average of the difference $v_{\mathrm{slip}}-v_{\mathrm{stick}}$, as a function of the imposed peeling velocity $V$. In (a) and (b), the continuous line corresponds to the imposed peeling velocity. Each data point is an average and the error bar the standard deviation over all stick-slip events in a single experiment. The large values of standard deviation at large peeling velocities are the trace of the intermittent occurrence of stick slip.

Figure 7

Parameter $(v_{\mathrm{slip}}-v_{\mathrm{stick}})/\langle v_{\mathrm{slip}}-v_{\mathrm{stick}}\rangle$, quantifying the normalized dependence of the velocity contrast between the slip and stick phases with the angular position of the peeling point ${\langle \alpha \rangle }_{ss}$ for various imposed peeling velocities $V$. Each data point corresponds to a single stick-slip event. The dotted line and the arrows indicate the time sequence of successive stick-slip events in the $V=2.41$ m s${}^{-1}$ experiment which reveals a large hysteresis loop.