A Tribometric Device for the Rolling Contact of Soft Elastomers

Rolling contact experimentation is a viable and instructive method for exploring the adhesive contact between surfaces. When applied to soft elastomeric or engineered surfaces, the results of such experiments can provide insights relevant to medical robotics, soft gripping applications, and reversible dry adhesives for bandages or wearable devices. We have designed and built a tribometric device to capture normal and tangential forces between a rolling indenter and substrate correlated with contact area imaging. The device was validated using an experimental setup involving a rigid, nominally smooth acrylic cylinder rolling against a flat polydimethylsiloxane (PDMS) substrate, the results of which matched favorably with accepted contact mechanics theories. The second test involved an indenter with a rigid core and thin (3 mm) smooth shell of a highly deformable polyvinyl chloride rolling on the same PDMS substrate. This test deviated significantly from analytical predictions, highlighting the effects of finite-thickness and rate-dependent phenomena. This device will facilitate experimental investigations of the rolling contact mechanics between textured surfaces and soft tissue-like materials, which is an important fundamental problem in medical robotics. Graphic Abstract