Barely visible impact damages of GFRP laminate profiles - An experimental study

The paper deals with experimental investigation of the composite channel section profiles subjected to low velocity impact with the energies of 10 and 20 J. The discussed structures were composed of eight-layer GFRP laminate with quasi-isotropic, quasi-orthotropic and angular ply arrangement of layers. The experimental results were compared with the theoretical model (1 DOF mass-spring system) and a coefficient was proposed that identifies deviations from the standard impact characteristics reported in the ASTM 7136. A new, not mentioned in the ASTM 7136 standard, characteristic curve was identified. Impacted flanges were characterized, despite the smoothing algorithm application, by a few minima and maxima and, in reference to BVIDs, by the worst repeatability of the results.