Modal acoustic emission of damage accumulation in a woven SiC/SiC composite

An approach to analyzing the tensile behavior and damage accumulation of ceramic composites is described and applied to a SiC-fiber-reinforced SiC-matrix composite. Monotonic tensile tests and load/unload/reload tensile tests were performed. Modal acoustic emission (AE) was used to monitor the extent of damage over the entire stress/strain curve. Microscopy of polished sections was performed to determine the extent of damage and related to the AE data. Damage accumulation in the matrix reduced the speed of sound through the matrix for acoustic events and was related to a reduction in elastic modulus. The location of events in the gage section was determined and related to the strain at which they occurred. The amplitude and frequency content of the event waveforms were used to correlate the acoustic events with the stress/strain curve and physical sources. (C) 1999 Elsevier Science Ltd. All rights reserved.