Simulation significant loss of overall stiffness can be estimated. The structural displacements and the extension of damage over the loading are illustrated in figure 9. More information SAMCEF uses a range of methods to simulate composites, including: -a comprehensive library of dedicated multi-layered elements, -a wide variety of material models and structural analyses, -dedicated pre- and post-processing procedures. Additionally, BOSS Quattro and its reliable optimisation algorithms help the engineer to design a composite structure taking into consideration damage tolerance, amongst other things (figure a). Fig. 8: The T-stiffened panel with the initial cracks, and the load-displacement curve Fig. a: The BOSS Quattro software developed by SAMTECH for designing composite structures Fig. 9: Displacements and damage propagation over the loading period Discussion Modelling and solving delamination problems in composites are known to be difficult, and the virtual testing capabilities offered by SAMCEF comply with the industrial reality. Some of the needs that have been identified at the industrial level include using large-size finite element models to efficiently represent reality; taking a large number of cracks in the structure into consideration in order to provide a safe design; modelling contact conditions over large areas; and obtaining accurate results. SAMCEF efficiently answers these industrial concerns with features such as easy definition of cracks and delamination zones; quick estimation of the propagation load via the VCE method; more advanced capabilities through the cohesive elements approach for interlaminar cracks propagation and estimation of the overall structural behaviour during the fracture process; a library of softening material laws for interlaminar behaviours; efficient strategies for treating contact conditions; accurate results (compared to reference solutions); and a parallel solution procedure for largescale problems. More information: www.samcef.com No41 June 2008 / JEC Composites Magazine 41http://www.samcef.com http://www.clairis-technologies.fr