High-speed thermal mapping and impact damage onset in CFRP and FFRP

The use of alternative, natural fibers instead of synthetic reinforcements in polymeric matrix composites, subjected to certain out-of-plane loads, requires a study on the susceptibility to damage. The aim of this work is to study the impact behavior and the stiffness reduction in flax and carbon fibre reinforced plastic laminates subjected to a 15 J drop-tower test. The detection of selected damage mechanisms was done by high-speed optical and infrared cameras monitoring the full-field deformation and temperatures on the composite surface. The elastic response of the laminates was modelled by a finite element method and ply failure was analyzed by the Hashin’s and Puck’s failure criteria. The results of thermal and strain measurements indicated the primary cracks due to the bending effect for the flax laminate. For the carbon laminate, the final fibre breaking was indicated. Numerical results showed the accuracy of the Puck’s criterion about the prediction of first stages of the impact failure.