Material Modelling for Blade Containment Simulations in Aircraft Engines
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Blade containment plays a crucial role in the safe operation of aircraft engines. It must be ensured that after a blade failure no high energy debris exits the engine casing and that the engine can be shut down safely. According to regulatory rules, successful blade containment must be demonstrated to certify the engine. The substantiation is either carried out by testing or by finite element simulations. A challenge for blade containment simulations is the complex material behaviour of aircraft engine materials such as titanium. In order to capture all relevant effects, the material model applied in this contribution considers elasto-plastic behaviour at large deformations combined with a sophisticated failure model. Thereby, an anisotropic yield behaviour as well as temperature and strain rate dependency is considered to describe the plastic deformation. The failure of metals depends on the stress state caused by microstructural effects driven by void growth under tensile loading and void elongation within a narrow shear band for shear dominated loading. In order to account for these complex failure mechanisms, a triaxiality and Lode parameter dependent failure strain model is applied. Thereby, different analytical failure models such as the Modified-Mohr-Coulomb as well as the Hosford-Coulomb failure model are compared. All model parameters are calibrated to a large set of specimens made out of titanium, accounting for a wide range of stress states, temperatures and strain rates. Finally, plate impact tests are carried out to validate the predicted deformation by the calibrated material model. Moreover, the failure behaviour of the plates under impact loading is compared to finite element simulations that are carried out with the different analytical failure models in order to investigate the best model performance.
