Interface debonding models: a viscous regularization with a limited rate dependency

Interface models have been developed over the past 10 years for simulating various scales of composite debonding effects, such as decohesion between matrix and fibers and delamination in laminates, formulated with and without rate dependencies. We give several examples of how sudden "solution jumps" can occur in rate-independent models like the Tvergaard depending on the geometry, interface behavior, and finite element discretization. This kind of instability disappears for the often-used viscous models, but the result is a high rate dependency that deviate from experimental trends. A new kind of viscous regularization is proposed here, which applies to the Tvergaard debonding model or modified ones, and has a limited rate dependency. A few simple examples are given, including the delamination of a double cantilever beam, to show the capabilities of the technique proposed. (C) 2001 Elsevier Science Ltd. All rights reserved.