“…Furthermore, in [ 22 ], the impacts are distinguished based on the potential energy of the impacting bodies, with values ranging from 500 mJ to 3.5 mJ. In other early studies on this subject [ 23 , 24 ], the impacts are instead distinguished based on the impact velocity. In several studies [ 24 , 25 , 26 ], signals that are generated by non-destructive impacts have been treated, which is, they do not cause any damage to the laminate under examination, neither with single impact nor with multiple impacts, however no information is given on the extent of impact.…”