Evaluation of Elastic Properties of Ceramic Matrix Composites via Impulse Excitation Technique and FEM Optimisation Studies

Kurzfassung

The German Aerospace Center (DLR) developed among others 3D printed quasi monolithic ceramics (SiSiC) and ceramic matrix composites (SiC/SiC) for energy and jet engine applications. These ceramic composites exhibit high strengths and long lifetimes under high temperatures (>1000°C). The characterization of material properties, which is required for accurate FEM modeling, is limited by manufacturing and machining processes. A method was developed to realistically generate certain missing room temperature properties. The non-destructive "Impulse Excitation Technique" (IET) was used to measure natural frequencies of 3D-printed SiSiC components and wound SiC/SiC components. Computed tomography scans were used to generate geometrical digital models including real defects. Using the geometrical models and some assumed material properties, modal analyses were performed in Ansys. Finally, the virtual material properties were optimized using Ansys optiSLang software; the optimization target was the experimental natural frequencies. The final result was a generation of realistic virtual material properties for 3D printed SiSiC and wound SiC/SiC components.