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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.

Universal Deformations in Inhomogeneous Isotropic Nonlinear Elastic Solids

Submitted by arash_yavari on
research
Universal deformations
Nonlinear elasticity
isotropic solids
inhomogeneous solids

Universal (controllable) deformations of an elastic solid are those deformations that can be maintained for all possible strain-energy density functions and suitable boundary tractions. Universal deformations have played a central role in nonlinear elasticity and anelasticity. However, their classification has been mostly established for homogeneous isotropic solids following the seminal works of Ericksen. In this paper, we extend Ericksen's analysis of universal deformations to inhomogeneous compressible and incompressible isotropic solids.

On the Interaction of Viscoelasticity and Waviness in Enhancing the Pull-Off Force in Sphere/Flat Contacts

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

Motivated by roughness-induced adhesion enhancement (toughening and strengthening) in low modulus materials, we study the detachment of a sphere from a substrate in the presence of both viscoelastic dissipation at the contact edge, and roughness in the form of a single axisymmetric waviness. We show that the roughness-induced enhancement found by Guduru and coworkers for the elastic case (i.e. at very small detachment speeds) tends to disappear with increasing speeds, where the viscoelastic effect dominates and the problem approaches that of a smooth sphere.

Precipitation during creep in magnesium-aluminum alloys

Submitted by SwarnavaGhosh on
research

Dear Colleagues,

I am writing to share with you my article titled, "Precipitation during creep in magnesium-aluminum alloys" , which has been published in the journal Continuum Mechanics and Thermodynamics. 

Lightweight magnesium-aluminum alloys show significant tension-compression asymmetry under creep loading. This work offers an explanation of this phenomenon.

Link to the article: https://rdcu.be/ct4zi

Variational principles for nonlinear pde systems via duality

Submitted by Amit Acharya on
research

Amit Acharya

A formal methodology for developing variational principles corresponding to a given nonlinear
pde system is discussed. The scheme is demonstrated in the context of the incompressible
Navier-Stokes equations, systems of first-order conservation laws, and systems of Hamilton-
Jacobi equations.

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