Frictional slippage of elastomeric disks compressed between rigid platens and subjected to torsion

A new analysis is applied to compressible, linearly elastic disks that are compressed by flat rigid platens. The disks are not bonded to the platens and Coulomb (Amonton) friction is assumed to act at the interfaces between the disk and the platens. Slip may occur in an outer annular region, while the inner circular (stick) region of the disk does not slip. The critical radius (slip boundary) is of major interest. The governing equilibrium equations in terms of the deflections are satisfied exactly. Approximations are made in some of the boundary conditions and the transition (matching) conditions at the critical radius. Numerical results are presented for nearly incompressible disks, both for (a) compression only and (b) compression plus torsion. In the latter case, during twisting, either the compressed thickness of the disk is fixed while the compressive force varies, or the compressive force is fixed while the thickness varies. The effects of the aspect ratio and Poisson's ratio of the disk, the coefficient of friction at the platens, and the twist angle on the critical radius, stresses, compressive force, torque, and effective compression and shear moduli are investigated. Applications include structural (especially bridge) bearings, seismic-isolation devices, mounting blocks and bushings, and rheometry.