Antonio Papangelo's blog

A compliantly fixed hemispherical indenter in adhesive contact with an elastic sample firmly bonded to a rigid base is considered under the assumption that the rigid base undergoes small-amplitude high-frequency normal (vertical) oscillations. A general law of the rate-dependent JKR-type adhesion is assumed, which relates the work of adhesion to the contact front velocity. Using the Bogoliubov averaging approach in combination with the method of harmonic balance, the leading-order asymptotic model is constructed for steady-state vibrations.

Just published on JMPS

Abstract

Title: “Experimental characterization of micropatterned interfaces subjected to dynamic loading” (PhD research project)

Main Research Project: SURFACE (ERC-2021-Startting Grant, https://doi.org/10.3030/101039198)

Scholarship: ≈20 k€/year (depending on taxes according to Italian regulations)

Duration: 3 years, starting Q1 2025

Advancements in smart soft materials are enhancing the capabilities of robotic manipulators in object interactions and complex tasks. Mechanochromic materials, acting as lightweight sensors, offer easily interpretable visual feedback for localized stress detection, structural health monitoring, and energy-efficient robotic skins. Herein, an innovative mechanochromic soft end-effector capable of discerning local contact stresses during mechanical interactions with objects is presented and their relative position is ascertained.

The contact between a rigid Hertzian indenter and an adhesive broad-band viscoelastic substrate is considered. The material behavior is described by a modified power law model, which is characterized by only four parameters, the glassy and rubbery elastic moduli, a characteristic exponent n and a timescale tau0.

In classical experiments, it has been found that a rigid cylinder can roll both on and under an inclined rubber plane with a friction force that depends on a power law of velocity, independent of the sign of the normal force. Further, contact area increases significantly with velocity with a related power law. We try to model qualitatively these experiments with a numerical boundary element solution with a standard linear solid and we find for sufficiently large Maugis–Tabor parameter � qualitative agreement with experiments.

The problem of the detachment of a flat indenter from a plane adhesive viscoelastic strip of thickness “b” is studied. For any given retraction speed, three different detachment regimes are found: (i) for very small “b” the detachment stress is constant and equal to the theoretical strength of the interface, (ii) for intermediate values of “b” the detachment stress decays approximately as b^{-1/2}1/2, (iii) for thick layers a constant detachment stress is obtained corresponding to case the punch is detaching from a halfplane.