Eur. Phys. J. B 39, 77-85 (2004)
https://doi.org/10.1140/epjb/e2004-00173-2

Torsional stiffness of viscoelastic spheres in contact

Laboratorium Landbouwwerktuigkunde, K.U. Leuven, Kasteelpark Arenberg 30, 3001, Leuven, Belgium

Corresponding authors: ^a Edward.Dintwa@agr.kuleuven.ac.be - ^b Engelbert.Tijskens@agr.kuleuven.ac.be

Received: 15 November 2003
Revised: 6 January 2004
Published online: 18 June 2004

Abstract

The theory of elastic contact between two spherical bodies according to Hertz, Mindlin and others is used as a basis for an extension to include the contribution of the viscous effects to the total stress for viscoelastic spheres subjected to twisting moments. Expressions relating twisting moment to the radius of a `stick' region of the contact surface and the radius of the `stick' region to twist angle are derived. Two term power series truncations of the relations are then used to derive approximate expressions for torsional stiffness of the bodies. Validation of the model was by experiments utilising a rheometer device. Applications for the model in post-harvest agriculture include extraction of material surface properties for use in discrete element modelling of mechanical interactions of fruits and other spheroidal produce during machine handling.