An improved cohesive zone model for ductile dynamic crack propagation
Tutor / director / evaluadorHendriks, Max
Tipo de documentoProyecto/Trabajo final de carrera
Condiciones de accesoAcceso restringido por acuerdo de confidencialidad
Ductile dynamic crack propagation is a current field of research in aerospace industry. The damage created by an explosion in a flying airplane depends on the fracture behaviour of the fuselage materials. Thus the rate of fracture for aluminium 2024 T3 is being studied. Analytical and empirical calculation methods do not predict correctly the experimental fracture velocity. Numerical simulations using cohesive elements with standard material models do not estimate it correctly either. Then a new numerical approach is being carried out which is focussed on a rate dependent (Perzyna) cohesive zone model. Basically, in this model the energy dissipated during the fracture depends on the fracture loading rate. To improve the accuracy of the time integration of the constitutive equations, an implicit scheme has been implemented and it has been checked the situations where a previous explicit implementation may be less accurate. New fracture experiments on aluminium pressurized barrels have been modeled using the Perzyna model. The results show a good agreement in terms crack behaviour and crack velocity. In addition it has been observed a big influence of the loads in fracture speed during the crack propagation.