Combined effects of viscoelasticity and surface roughness on the adhesion behavior of a flat-end cylindrical microstructure

•An adhesion model is developed to characterize the contact between a viscoelastic microfibril and a rough rigid substrate.•The rate-dependent adhesion hysteresis and the roughness-induced hysteresis are comprehensively considered.•A numerical scheme is proposed to make the rate-dependent adhesion model compatible with the randomly rough contact model.•There is an optimal surface roughness at which the surface adhesion strength is the strongest. A theoretical modeling approach is developed to simulate the rate-dependent adhesion contact between a single flat-end cylindrical microstructure and a randomly rough rigid surface. This model combines the Greenwood-Williamson rough contact model and the rate-dependent JKR model for viscoelastic dynamic contact, which can comprehensively consider the roughness-induced adhesion hysteresis and the rate-dependent adhesion hysteresis. A numerical scheme is proposed to make the rate-dependent adhesion model compatible with the randomly rough contact equation. The proposed method is verified well by comparing with the Fuller & Tabor model at a very low approach/detachment speed. The effects of surface roughness and viscoelastic material constant on adhesion strength and energy dissipation are evaluated. Results indicate that there is an optimal surface roughness at which the surface adhesion strength is the strongest, and a worst roughness that minimizes the energy dissipation. The effect of viscoelastic material constant depends on the approach/detachment speed of the microstructure. A higher approach/detachment speed causes the adhesion strength and the energy dissipation to change significantly with viscoelastic material constant, while a low speed does not.