Numerical simulation of fragmentation of composite material plates due to impact

Fragmentation is the mechanism by which composite structures absorb energy during a crash event. This mechanism is substantially different from that developed by metallic structures where energy is absorbed by large plastic deformations. Fragmentation is the result of different simultaneous and complementary events because of the non-homogeneous nature of the composite material. The material that constitutes every single lamina may fail in the matrix, either in tension or in compression, and/or in the fibres. Moreover, laminate failure occurs when ail the laminae fail completely at some location, so that the material can no longer carry the external loads at this location. The phenomenon, therefore, needs an appropriate specific model. After the basic specific theory of composite laminate failure has been briefly addressed, an original model based on the description of the progressive damage of a composite material, with particular emphasis on the strength of a lamina, both before and after failure, when its mechanical characteristics partially or totally degrade, is presented. This model has been implemented in the well-known DYNA3D explicit finite element code, the new features are outlined briefly. Finally, results obtained by numerical simulation and experimental testing of the behaviour of composite material plates submitted to impact loading are shown and compared for validation.Two different cases are analysed: in the first, the plate is damaged but not perforated, while in the second, the plate is completely perforated. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.