An upper bound solution for a solid viscous cylinder subject to compression and twist

The upper bound technique is adopted to investigate the effect of angular velocity and viscosity on the load and torsion moment required to compress a circular solid cylinder made of viscous material between two rotating plates. The kinematically admissible velocity field accounts for the behavior of the actual velocity field in a vicinity of the friction surface and the plane of symmetry. The theoretical solution is illustrated by numerical examples for different geometrical parameters. In particular, the variation of dimensionless work rate, torsion moment and compression force with the dimensionless angular velocity are shown.