Session: 02-01 Mechanical Behavior of Ceramics and Composites

Paper Number: 121309

121309 - Cluster Analysis of Acoustic Emission Signals From SiC/SiC CMCs Including the Introduction of Waveguides and the Effect of Material Changes Under Thermal Exposure 

Ceramic matrix composites (CMCs) have received significant attention due to their advantageous material properties for engineering applications where temperatures approach or exceed the working limits of traditional metals and alloys. An understanding of the damage mechanisms that accumulate within the material under complex mechanical and thermal stress conditions is therefore essential. Acoustic emission (AE) is one form of non-destructive evaluation (NDE) that is routinely used for such assessment. This paper investigates the application of pattern recognition tools to AE data obtained from monotonic tensile testing of SiC_f/BN/SiC CMCs under thermal exposure in a range between room temperature (RT) and 1100°C.

Unsupervised pattern recognition in the form of k means clustering was subsequently applied to the AE datasets in efforts to link different AE signal characteristics with damage mechanisms anticipated at specific stresses within the CMC. At RT, commonly occurring clusters were attributed to damage modes such as matrix cracking and interfacial debonding/sliding, with attempts to validate these signals via secondary experiments. Similar clusters could still be identified upon the introduction of waveguides that were necessary for obtaining signals at high temperatures. Tensile tests were then performed at increasing temperatures and the cluster activity was compared in efforts to link thermally-induced degradation of the material to the observed AE behaviour.

Presenting Author: Zak Quiney Swansea University Institute of Structural Materials

Presenting Author Biography: Graduated with a PhD in mechanical engineering in 2013 and currently employed as a post-doctoral research officer within the Rolls-Royce University Technology Centre at Swansea University Institute of Structural Materials (ISM). Specialising in Ceramic Matrix Composite (CMC) materials testing and non-destructive evaluation techniques including acoustic emission, vibration, microwave dielectric and X-ray computed tomography.

Authors:

Zak Quiney Swansea University Institute of Structural Materials
Louise Gale Rolls-Royce Plc
Stephen Pattison Rolls-Royce Plc.
Gonzalo Garcia Luna Rolls-Royce Plc.
Chris Newton Swansea University Institute of Structural Materials
Martin Bache Swansea University Institute of Structural Materials
Spencer Jeffs Swansea University Institute of Structural Materials