Acoustic Emission Assessment of FRP Composites Delamination

Delamination is one of the most common failure modes of composite materials. It may result from imperfections in the production process or may be caused by service life conditions, such as impact by foreign objects. The presence of delamination in the composite material may reduce the overall stiffness. The geometrical parameters, material properties, loading conditions and mid-plane layouts are important factors which effect the initiation and growth of delamination. In this paper different types of mid-plane layouts are used. Test set up involved double cantilever beam to detect delamination of mode I. Experimental results have obtained from monotonic tests and have been shown good agreement between crack-growth data. Previous studies made on different composite materials have allowed us to set up a schematic model of acoustic emission. At current work, both different levels of absolute energy of acoustic emission signals (E_cum) and mechanical energy (G_Icum) are identified for different mid-plane layouts. The experimental method has been applied to this work and allows continuous and alive monitoring of damage growth through delamination tests. Finally, used method by acoustic emission to obtain G_Ic was not in good agreement with ASTM methods and it is needed to find a new method based on acoustic emission to obtain G_Ic.