Load Transfer and Deformation Mechanisms at Interfaces Between Snakeskin-Inspired Surfaces and Sand

The performance of geotechnical systems may be optimized using surface textures that mobilize direction-dependent skin friction. Snakeskin-inspired surfaces generate low friction in the caudal (i.e. along the mild slope of asperities) direction and high friction in the cranial (i.e. against the sharp edge of asperities) direction. This investigation uses discrete element modelling to analyze the particle- and asperity-level mechanisms that govern the transfer of load at interfaces with snakeskin-inspired surfaces. Particle displacements, contact networks and force distributions reveal the mobilization of passive wedges during cranial shearing, while sliding along the asperities’ mild slope controls the behavior during caudal shearing. Decomposition of the forces acting on individual asperities shows that increases in asperity height and length produce increases of the passive and normal forces, but they have a modest effect on the sliding force. Consideration of the number of asperities per unit surface length unifies the trends with a single relationship with the ratio of asperity length to height. The failure envelopes for the snakeskin-inspired interfaces exhibit slight curvature due to the nonlinear dependence of the asperity forces with normal stress. This investigation sheds light on the mechanisms controlling frictional directionality, which can provide guidance for the development of design procedures for snakeskin-inspired geotechnical elements.