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Antonio Papangelo's blog

Can wear completely suppress thermoelastic instabilities?

Submitted by Antonio Papangelo on

ThermoElastic Instabilities (TEI) occur in sliding bodies at sufficiently high speed because a small thermoelastic disturbance tends to localize the contact, leading to “hot spots”. The role that wear plays in TEI has been studied briefly and only on highly idealized cases. We extend and complete in detail a model of Dow and Burton who studied the specific configuration of a blade sliding on a rigid halfspace normal to its line of contact. We find there is a limit value of wear coefficient, that can be estimated by simple equations, above which TEI is completely eliminated.

Friction-induced energy losses in mechanical contacts subject to random vibrations

Submitted by Antonio Papangelo on

In this paper, we apply the previously developed Method of Memory Diagrams (MMD) to the description of an axisymmetric mechanical contact with friction subject to random vibrations. The MMD belongs to a family of semi-analytical methods of contact mechanics originating from the classical Cattaneo-Mindlin solution; it allows one to efficiently compute mechanical and energetic responses to complex excitation signals such as random or acoustic ones.

On stickiness of multiscale randomly rough surfaces

Submitted by Antonio Papangelo on
A new stickiness criterion for solids having random fractal roughness is derived using Persson's theory with DMT-type adhesion. As expected, we find stickiness, i.e., the possibility to sustain macroscopic tensile pressures or else non-zero contact area without load, is not affected by the truncation of the PSD spectrum of roughness at short wavelengths and can persist up to roughness amplitudes orders of magnitude larger than the range of attractive forces.

The effect of wear on ThermoElastic Instabilities (TEI) in bimaterial interfaces

Submitted by Antonio Papangelo on

There is ample evidence of ThermoElastic Instabilities (TEI) occurring in sliding contacts. The very first experiments of JR Barber in 1969 suggested wear interacts in the process of localization of contact into ”hot spots”. However, studies on the interaction of TEI with wear are scarce. We consider the case of two sliding halfspaces and make a perturbation analysis permitting the formation of waves migrating over the two bodies, in presence of wear. We find that for exactly identical bodies wear does not affect the stability boundary.

Citation metrics author database for many scientific fields

Submitted by Antonio Papangelo on

Citation metrics are widely used and misused.  Ioannidis and co-authors have created a publicly available database of 100,000 top scientists that provides standardized information on citations, h-index, coauthorship-adjusted hm-index, citations to papers in different authorship positions, and a composite indicator.

Reconstruction of Governing Equations from Vibration Measurements for Geometrically Nonlinear Systems

Submitted by Antonio Papangelo on

Data-driven system identification procedures have recently enabled the reconstruction of governing differential equations from vibration signal recordings. In this contribution, the sparse identification of nonlinear dynamics is applied to structural dynamics of a geometrically nonlinear system. First, the methodology is validated against the forced Duffing oscillator to evaluate its robustness against noise and limited data.

Axisymmetric JKR-type adhesive contact under equibiaxial stretching

Submitted by Antonio Papangelo on
 Our research has just been published in Journal of Adhesion. It deals with axisymmetric frictionless adhesive contact problem for a spherical indenter pressed against an isotropic elastic incompressible half-space under equibiaxial stretching is studied in the framework of the generalized Johnson{Kendall{Roberts (JKR) theory, which accounts for the effect of weak coupling between fracture modes I and II by means of a phenomenological mode-mixity function. The model predicts that contact area can withstand a larger level of the substrate stretch under moderate pre-pulling force.