Figure 3.
Steady-state contact forces of the GSA as a function of drag speed over drag distances of 10−1 mm (open circles), 100 mm (filled circles), 101 mm (open squares) and 3× 101 mm (filled squares). (a) Friction forces increased with speed until approximately 10 mm s−1 at which point friction decreased with speed. (b) Adhesion force followed the friction force. Line fits are Fshear = (0.020 N)(1 + v/(52.4 mm s−1))−1sinh−1(v/(1.5 × 10−6 mm s−1)) + 0.511 N (R2 = 0.96) and Fnormal = (−0.014 N)(1 + v/(52.4 mm s−1))−1 sinh−1(v/(1.5 × 10−6 mm s−1)) − 0.025 N (R2 = 0.91).