FRACTURE OF A BRITTLE MEMBRANE

The fracture of a brittle membrane by a localized transverse impact is studied using a numerical lattice model. The fracture patterns which are found experimentally [N. Shinkai, in Fractography of Glass, edited by R. C. Bradt and R. E. Tressler (Plenum, New York, 1994)] by droppi ng a heavy ball on a thin glass plate are reproduced. At a very high i mpact velocity only a small hole is created at the impact area (Hertzi an fracture). At lower velocities tangential and radial cracks are for med. In the model calculations, pure Hertzian fracture appears in the limit where inertial forces dominate over the elastic forces, while ta ngential fracture appears in the opposite limit. Radial cracks are dem onstrated to be a consequence of nonlinear deformations or an external ly applied in-plane strain. [S0031-9007(97)04464-5].