EXTRACTION OF HISTORIES OF DAMAGE MICRO-MECHANISMS IN UNIDIRECTIONAL COMPOSITES BY TRANSIENT-PARAMETRIC ANALYSIS

摘要

The problem of micro-damage evolution to failure in advanced composites is addressed. A combination of transient waveform classification and multi-parametric filtering was used to extract the histories of damage evolution in a unidirectional graphite/epoxy composite loaded in the fiber and transverse directions. Three characteristic AE waveforms with different amplitudes, durations, and frequency spectra were identified based on the transient analysis. The waveforms were associated with matrix cracks, fiber breaks, and longitudinal splitting in the composite. Parametric regions for the characteristic waveforms were identified in the amplitude-rise time parametric space. Multi-parametric filtering was applied to extract the micro-damage evolution histories. The method is expected to be advantageous for the real-time damage and fracture monitoring of composite structures.