Stitching Effect on Impact Behaviour of Composite Materials

In this work, the low velocity impact behavior of laminated polypropylene/plain woven basalt structures was investigated. In particular, given the extraordinary resistance of these structures to perforation, which has already emerged from previous investigations, the authors wanted to verify whether the possible presence of transverse junction points could further enhance this interesting mechanical behavior. However, in line with contradictory evidence already present in the literature regarding the use of seams, regardless of their arrangement, the impact results, collected with dart drop tests, highlighted the non-influence of stitches on the damage extent of the composite system examined.In particular, with the same impact energy, the load deflection curves are almost superimposable even if minimal differences have been found in terms of external plastic deformation (indentation depth) as the stitch configuration varies. Furthermore, the arrangement of through thickness constraints affects the extent of the delaminated area.