Evolution of interfacial voids around a cylindrical inclusion

The formation and evolution of interfacial cavities is predicted for compression flows of a viscous solid around a rigid cylindrical inclusion. The resulting free-boundary problem is solved by the finite element method with boundary-fitted mesh motion. The matrix inclusion interface is perfectly weak and separates at a dynamic contact line. For a fixed set of geometric parameters, increasing the external pressure causes smaller interfacial voids and slower growth rates. The size of the stagnant voids found is affected by the applied pressure. The profiles of interfacial voids change from convex to convex-concave as the strain increases. This can lead to unstable cusps at low enough external pressures. The numerical predictions compare well with the experiments of Kao and Kuhn (1990) for void size as a function of strain in viscoplastic model materials.