Comparison between Low Velocity Impact and Quasi-Static Indentation Tests on CFRP Composite Laminates

According to several studies, the damage produced in laminated composites during quasi-static indentation tests may be considered similar to the damage caused by foreign object impact. In order to verify this similarity rigorously, low velocity impact and quasi-static indentation tests were done on quasi-isotropic carbon fibre-epoxy resin matrix laminated plates; the elastic behaviour and material damage induced in the two cases were compared. Both dynamic and quasi-static tests were simulated by a two-dimensional finite element model including geometrical nonlinearity. The examination of failures by visual inspection and by optical and scanning electron microscope showed qualitatively similar damage types in impacted and indented specimens: surface indentation, back-face splitting, delamination, fibre fracture and fibre kinking. On the other hand, energy considerations, together with load-displacement relationship and numerical analysis, indicated that in impacted specimens damage is somewhat more severe, thus limiting the validity of the analogy between low velocity impact and quasi-static indentation.