Table 3 Summary of interface friction strength using modified direct shear apparatus with various scale geometries, three vertical stresses, and two-way shearing directions: (a) Cranial → Caudal; (b) Caudal → Cranial.
From: Estimation of interface frictional anisotropy between sand and snakeskin-inspired surfaces
L [mm] | H [mm] | (a) Cranial → Caudal | |||||
|---|---|---|---|---|---|---|---|
Cranial first shearing | Caudal second shearing | ||||||
σ′v [kPa] | τpeak [kPa] | ϕpeak [°] | σ′v [kPa] | τpeak [kPa] | ϕpeak [°] | ||
6 | 0.3 | 50 | 60.9 | 45.1 | 50 | 24.3 | 28.7 |
100 | 109.5 | 100 | 49.5 | ||||
200 | 193.5 | 200 | 112.9 | ||||
12 | 0.3 | 50 | 48.2 | 41.4 | 50 | 19.7 | 23.9 |
100 | 96.3 | 100 | 37.8 | ||||
200 | 171.7 | 200 | 72.4 | ||||
18 | 0.3 | 50 | 40.9 | 32.3 | 50 | 18.3 | 20.5 |
100 | 84.1 | 100 | 40.1 | ||||
200 | 113.3 | 200 | 73.5 | ||||
24 | 0.3 | 50 | 30.9 | 28.4 | 50 | 17.9 | 20.6 |
100 | 57.5 | 100 | 36.7 | ||||
200 | 105.4 | 200 | 76.0 | ||||
12 | 0.1 | 50 | 23.7 | 24.1 | 50 | 16.9 | 21.4 |
100 | 43.7 | 100 | 34.6 | ||||
200 | 89.7 | 200 | 81.5 | ||||
12 | 0.45 | 50 | 64.3 | 45.1 | 50 | 18.2 | 26.9 |
100 | 108.7 | 100 | 47.0 | ||||
200 | 193.0 | 200 | 105.6 | ||||
12 | 0.72 | 50 | 64.8 | 46.6 | 50 | 25.9 | 32.2 |
100 | 115.1 | 100 | 65.2 | ||||
200 | 203.6 | 200 | 126.3 | ||||
L [mm] | H [mm] | (b) Caudal → Cranial | |||||
|---|---|---|---|---|---|---|---|
Caudal first shearing | Cranial second shearing | ||||||
σ′v [kPa] | τpeak [kPa] | ϕpeak [°] | σ′v [kPa] | τpeak [kPa] | ϕpeak [°] | ||
6 | 0.3 | 50 | 24.8 | 25.3 | 50 | 65.4 | 45.7 |
100 | 50.3 | 100 | 114.1 | ||||
200 | 92.9 | 200 | 196.4 | ||||
12 | 0.3 | 50 | 17.8 | 21.1 | 50 | 58.5 | 43.0 |
100 | 40.9 | 100 | 103.4 | ||||
200 | 76.3 | 200 | 178.6 | ||||
18 | 0.3 | 50 | 21.2 | 20.8 | 50 | 44.9 | 37.3 |
100 | 39.8 | 100 | 91.7 | ||||
200 | 74.6 | 200 | 143.2 | ||||
24 | 0.3 | 50 | 21.2 | 20.6 | 50 | 36.9 | 30.9 |
100 | 38.9 | 100 | 68.6 | ||||
200 | 74.0 | 200 | 114.0 | ||||
12 | 0.1 | 50 | 17.0 | 17.7 | 50 | 32.9 | 30.7 |
100 | 26.9 | 100 | 48.8 | ||||
200 | 66.3 | 200 | 123.5 | ||||
12 | 0.45 | 50 | 23.4 | 23.6 | 50 | 65.5 | 45.3 |
100 | 43.4 | 100 | 109.5 | ||||
200 | 81.6 | 200 | 194.3 | ||||
12 | 0.72 | 50 | 22.7 | 32.1 | 50 | 66.5 | 45.8 |
100 | 66.9 | 100 | 115.9 | ||||
200 | 125.6 | 200 | 195.2 | ||||
Untextured | 50 | 12.1 | 13.9 | 50 | 12.1 | 13.9 | |
100 | 27.7 | 100 | 27.7 | ||||
200 | 48.3 | 200 | 48.3 | ||||
