Institute of Structures and Design
Area of research:
Lifetime prediction of ceramic matrix composites with consideration of plasticity in the material
In the department of ceramic composite structures at DLR (German Aerospace Center), Institute of Stuctures and Design, ceramic matrix composites (CMC) have been developed since the late 1980s. These materials exhibit damage tolerant fracture behavior, good thermal shock resistance and insensitivity towards cyclic fatigue. So called C/C-SiC materials are manufactured via liquid silicon infiltration (LSI), a robust process based on three characteristic steps: (1) Manufacture of a CFRP preform; (2) Pyrolysis, resulting in a porous C/C preform; (3) Siliconization by capillary infiltration of Si in the C/C preform and chemical reaction of Si with C, building up a SiC matrix. The resulting microstructure is complex and highly anisotropic in nature. In recent years, effort has been made to capture the material behaviour accurately with the help of constitutive equations based on continuum mechanics. The main task of this internship will be to extend the existing models in the department to include plastic strains.
The work will comprise:
Understanding the existing material models Literature review for available plasticity models in brittle materials Development of constitutive equations based on continuum mechanics Validation of models with the help of experimental results Integration of model in existing tool architecture to predict lifetime of CMCs