PSI - Issue 79

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 79 (2026) 306–312

© 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IGF28 - MedFract3 organizers Keywords: viscoelasticity; dynamic adhesion; fibrils; contact Abstract This study presents a semi-analytical solution for the adhesive contact between a rigid sphere and an array of viscoelastic fibrils, modeling interactions which are commonly encountered in biological adhesion and engineered surfaces. The viscoelastic behavior of the fibrils is modelled using a standard viscoelastic solid (SVS) model, capturing both elastic and time-dependent deformation responses. The contact problem is formulated by considering the normal approach of the rigid sphere onto the fibrillar surface, dominated by a harmonic displacement law, and implementing different adhesive contact criteria. The analysis provides the pull- off force as function of the vibrations’ frequency and amplitude, also highlighting the dependence from the material parameters and providing insights into vibrating detachment processes. 1. Introduction Soft robots are making a big impact in pick-and-place operations, especially in industries that require handling fragile, irregular, or delicate items where rigid grippers fail. Among the different soft robots’ families, some of them are based on exploiting pick-and-place operations by means of dynamic adhesion, namely adhesion under micro- 28th International Conference on Fracture and Structural Integrity - 3rd Mediterranean Conference on Fracture and Structural Integrity A model for the dynamic adhesion between rigid and viscoelastic bodies America Califano a * * , Gabriele Cricrì a a Department of Industrial Engineering, University of Naples “Federico II”, P.le Tecchio 80, 80125, Naples (Italy)

* * Corresponding author. E-mail address: america.califano@unina.it

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IGF28 - MedFract3 organizers 10.1016/j.prostr.2025.12.338