ANALYSIS OF DAMAGE MECHANISMS IN A CENTRALLY NOTCHED GLASS-FIBER EPOXY PLATE

The object of this study is to investigate the damage and failure mech anisms in a glass-fiber/epoxy composite under monotonic tensile loadin g. The testing was carried out on unidirectional specimens with and wi thout a circular hole. The damage initiation and failure mechanisms we re studied by means of scanning electron microscopy and acoustic emiss ion monitoring. In addition, for specimens with a circular hole, a nov el strain-gage instrumentation method is suggested. These different te chniques permitted the determination of the damage parameters e, v, D, F, which characterize qualitatively and quantitatively the initiation and evolution of damage, ft was found that the amplitude distribution of acoustic emissions is a very efficient tool for identifying damage mechanisms such as microcracking in the resin, fracture and friction of the interface between fiber and matrix, and fiber pull-out.