4. Conclusion: towards the materials of the future

The frictional transition model, validated by numerical simulations, microscopic experiments (particle-scale measurements) and macroscopic experiments (suspension-scale measurements), provides a coherent framework for describing rheo-thickening. All the results presented in this article show that this phenomenon is due to the presence of a repulsive force between the particles, which induces non-rubbing or rubbing behavior of the particles depending on the stresses present within the system. The sudden increase in viscosity observed during this transition is linked to the fact that the critical volume fraction ϕ _c of a suspension depends on the frictional state of the particles.

These results show that the physics of nanometric and micrometric contact between particles has a major impact on the macroscopic behavior of...