A parametric contact model to describe the interlocking of soft bodies with ridged surface textures used in haptic applications

Abstract

Tactile interactions with product surfaces are essential to how such products are used and the value that users ascribe to them. It has been shown that contact mechanisms and frictional interactions are central to the haptic attributes perceived by the users. While there are established and well-studied models that describe the adhesive and deformation components of friction, interlocking behavior—while shown to be dominant in some tactile applications—has not been thoroughly studied as a frictional mechanism for soft materials such as skin, partly because of the complex contact mechanics involved. This investigation involved a computational parametric study of interlocking behavior between a soft material and a parallel-ridge surface texture, across a range of ridge widths, spacing and applied pressure. The goal of the work was to determine if a relatively simple contact model could be developed to predict the number of potential points of interlocking between the soft body and the ridge features. The results showed that a standard Hertzian approach predicted the number of ridge edge contacts (potential interlocking locations) with acceptable accuracy, so long as the ratio of ridge width to ridge spacing was large. However, a hybrid model that also incorporated the ridge width performed remarkably well across a wide range of ridge widths and spacing. This model may provide utility as an input into various proposed models of frictional interlocking to explain haptic perception of textured surfaces.