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Antonio Papangelo's blog

Viscoelastic increase of detachment stress of a rigid punch from adhesive soft viscoelastic layers

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction; viscoelasticity

The problem of the detachment of a sufficiently large 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, (iii) for thick layers a constant detachment stress is obtained corresponding to case the punch is detaching from a halfplane.

PhD positions opening in contact mechanics at PoliBa

Submitted by Antonio Papangelo on
job

Location: Polytechnic University of Bari, Department of Mechanics Mathematics and Management (DMMM), Via Orabona 4 - 70125 Bari – Italy

Job Type: Full Time

Deadline: A few PhD positions will open soon and every year starting June 2022, deadline to be announced. The application will include CV but also a well written potential project which has to be preliminary discussed with the supervisors.

Viscoelastic dissipation in repeated normal indentation of an Hertzian profile

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction; viscoelasticity

Simple exact solutions are known for the indentation problem of a viscoelastic halfspace by a rigid sphere only as long as the contact area is growing. We consider instead a more general cyclic repeated indentation with a pulsating load with a period of zero load. We show that a combination of exact with empirical relaxation solutions coming from simple uniaxial cases is sufficiently accurate to estimate the energy dissipated per cycle, which we report for the standard ”3-elements” solid and periodic half-sine loading for various parameters.

Viscoelastic normal indentation of nominally flat randomly rough contacts

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction; viscoelasticity

Viscoelastic materials are receiving increasing attention in soft robots and pressure sensitive adhesives design, but also in passive damping techniques in automotive and aerospace industry. Here, by using the correspondence principle originally developed by Lee and Radok and further extended by Ting and Greenwood, we transform the elastic solutions of Persson for contact of nominally flat but randomly rough surfaces to viscoelastic indentation. As an example, the cases of step loading and of the response to a single cycle of harmonic loading are studied.

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