Experimental assessment of low velocity impact damage in flax fabrics reinforced biocomposites by coupled high-speed imaging and DIC analysis

Structural composite materials with good impact resistance are required in several industrial sectors to design parts submitted to crashes or falling objects. This work investigates the impact behaviour of flax fabrics-epoxy and commingled flax-polypropylene (PP) fibres composite plates manufactured using compression moulding process. An instrumented drop tower was used to conduct low velocity impact tests at several energies and high-speed imaging coupled with DIC analysis was used to assess the damage evolution. A crack-tracking algorithm was implemented in ImageJ to identify the initiation and propagation of cracks. A comparison of the force-displacement histories and high-speed camera results for both composites were used to identify the different modes of damage and the critical energy for complete penetration. The proposed method is able to depict the successive events that lead to the breakage of biocomposites and it will be a valuable tool to investigate the impact behaviour of other materials as well.