livMatS Colloquium | Prof. Julien Scheibert (Ecole Centrale de Lyon) | Metainterfaces with specified friction laws : new designs from numerical optimization

Abstract
Optimizing devices like robotics hands requires fine control of the interface’s friction law. We recently proposed a generic surface design strategy to prepare dry rough soft interfaces having predefined relationships between normal and friction forces [1]. Such metainterfaces are made of assemblies of spherical asperities that, collectively, produce an emergent macroscopic friction law. The height of each asperity is prescribed through inversion of a suitable upscaling model. So far, the inversion has been analytical, strongly limiting the number of accessible friction laws. Here, we use genetic algorithms to identify complex designs meeting previously unaccessible specifications. For instance, we obtain metainterfaces with on-demand values of the friction coefficient, without changing the pair of materials in contact. Our new designs are validated experimentally on glass/polydimethylsiloxane (PDMS) metainterfaces. Overall these results lay the foundations for automated ways of designing soft contact interfaces with a large breadth of desired friction behaviour.
[1] A. Aymard, E. Delplanque, D. Dalmas, J. Scheibert. Designing metainterfaces with specified friction laws. Science 383, 200-204 (2024) .

Brief Bio
Julien Scheibert is director of research at CNRS. His research interests lie at the interface between physics and mechanics, with an effort on establishing quantitative links between experiments and modelling. His work has focused on :

• human tactile perception, including the role of fingerprints in texture perception;
• the rapid fracture of brittle heterogeneous solid materials ;
• the sliding dynamics of contact interfaces between rough solids.
  Julien Scheibert has expertise in the contact mechanics of dry rough interfaces, particularly for soft materials such as elastomers. He is now developing metainterfaces, the microstructure of which is optimised to provide tailor-made friction properties.