Investigating the impact behaviour of short hemp fibres reinforced polypropylene biocomposites through high speed imaging and finite element modelling

In several industrial sectors, structural composite materials with good impact resistance are required to design parts submitted to crashes or falling objects. This work analyses the impact behaviour of short hemp fibres reinforced biocomposites through mechanical measurements, high speed imaging and finite element modelling. A drop-weight impact machine was instrumented with a high speed camera to measure the propagation of macro-cracks and correlate it to the force-displacement dynamic response at several impact energy levels. PP-hemp composites exhibit higher absorbed energies (up to 40%) than PP-glass composites due to higher strain at break. The video tracking analysis highlights that for a given cumulated crack length, PP-hemp composite absorbs much more energy, related to differences in failure mechanisms. The developed finite element model is in good agreement with the experimental measurements and the fracture growth pattern, thus constituting a useful tool to predict the impact response of biocomposite parts.