Free edge effects study in laminated composites using Digital Image Correlation: effect of material and geometrical singularities

Composite materials are today used for various industrial applications. However, delamination on free edges, where stress gradients are strong, still remain a problem. In the aim of a better understanding of such phenomenons, Digital Image Correlation (DIC) measurements have been carried out on [(15(n)/15(n))(2)](s) laminates under uniaxial tensile strain. Three different composites with different mechanical properties and microstructure have been tested as well as two samples geometries: flat and with ply drop. Experimental results show high shear strain concentrations near 15 degrees/-15 degrees interlaminar interfaces on free edges which depend on material mechanical properties and microstructure and increase in the vicinity of a geometrical singularity.