Non Destructive Evaluation of a Ceramic Matrix Composite

Background of Study

• Non destructive evaluation (NDE) application
• Based on industrial CT scan
• Visualisation and segmentation of internal anomalies

In this study, dog bone shaped specimens were extracted from a panel made out of a ceramic matrix composite (CMC) material, which consists of 40% Sylarmic fiber, 6-7% porosity, Boron Nitride (BN) internal coating, 20-25% Chemical Vapor Infiltrated (CVI)-SiC coating, and Melted Infiltrate (MI) matrix. The material was fatigue tested and CT scanned before and after cycling to characterize the initial matrix porosity’s distribution and sizes.

CT scan
For this study, 20 2D slices of around 0.2 mm were required, given the accuracy of the CT system used in this study. The in-plane resolution of the scanner was 0.2mm (in both X and Y directions), whereas the separation between each slice was 1.25 mm.

Mesh Generation in ScanIP and +ScanFE
Ten models were generated within +ScanFE using different smoothing algorithms and mesh densities, in order to explore the sensitivity of the numerical predictions to a range of parameters. A screenshot of the FE mesh shows the internal features illustrating various anomalies within the ceramic materials.

FE Analysis in ABAQUS and Ansys
A series of FE analyses were carried out illustrating the accuracy of the novel image based modelling algorithms implemented in the software. The work demonstrates that FE models based on an accurate 3D model from CT data are an essential tool to quantify the effects of internal defects in complex material systems such as CMCs. This research project was carried out in collaboration with NASA Glenn Research Center, Cleveland, USA.

Publication
Abdul-Aziz, A., Saury. C., Bui Xuan, V., Young, P., 2006. On the material characterization of a composite using micro CT image based finite element modeling. In: Smart Structures and Materials and NDE, 26 February-2 March 2006 San Diego. Bellingham: SPIE.