Study of the damage by acoustic emission of two laminate composites subjected to various levels of loading in three points bending

Abstract

We present on this paper an experimental study of the follow-up of the damage of two laminate composites manufactured by RTM during their loadings in 3 points bending in static and cyclic tests. These materials are com-posed E glass fibres and epoxy resin. The mechanical tests are carried out on a standard hydraulic machine INSTRON 8516 that can be used in static and fatigue tests. The ma-chine is interfaced whith a detected computer for control-ling and data acquisition. The evolution of the damage is followed by acoustic emission using the system EPA NCV-2 connected to the testing machine, then confirmed by optical microscopic observations. The results obtained show that the curves of mechanical behaviour are strictly related to the observed damages. In the case of cyclic bending, the increase in the number of cycles involves a modulus reduction for the two materials that in loading as well as in unloading. The Acoustic emission allows to lo-cate the mechanisms of damage and rupture caused by the loading of these materials.