Application of the Acoustic Emission Technique for Damage Monitoring of 3D C/C

摘要

This paper deals with the detection and monitoring of damage of a three-dimensional carbon/carbon composite (3D C/C) under tensile loading. In fact, due to the manufacturing process, the existing cracking network of 3D C/C at the initial state may be quite extended which may affect the mechanical behavior and in some cases lead to the premature rupture under loading. The objective of this work is to investigate the validity of the acoustic emission as an advanced health monitoring system to provide warning of the distress and characterize the damage state during loading. Load-unload-reload tensile tests have been conducted and monitored in parallel with the Digital Image Correlation (DIC) method and the acoustic emission (AE) technique. The AE technique allows to monitor the evolution of damage inside the volume of the material and the growth in situ. This is very interesting since the other nondestructive techniques usually used allow only a posteriori evaluation of damage. The influences of stress states on tensile properties and the dependency with the AE activity have been analysed. Different stages of damage have been identified based on the acoustic emission activity and AE signals parameters. In addition, the AE technique provides accurate location of damage based on the density of AE events location maps.