Green sandwich structures under impact: experimental vs numerical analysis

Nowadays, there is a growing interest for the use and development of materials synthesized from renewable sources in the polymer composites manufacturing industry; this applies for both matrix and reinforcement components. In the present research, flax fibers embedded in an epoxy resin have been proposed as an environmentally friendly alternative to traditional synthetic composites. In addition, this material system has been combined with agglomerated cork as core material for the fabrication of sandwich structures. The objective of this article is to analyze the suitability of using such green sandwich structures in applications where energy absorption due to low velocity impacts can be of importance. Therefore green sandwich specimens with flax/epoxy face sheets and agglomerated cork as core have been manufactured and subjected to low velocity impacts at different energies. After the mechanical characterization of both skin and core material, a numerical model has been implemented through the non-linear dynamic code LS-DYNA. The FE analysis has been able to reproduce with a good level of accuracy the deformation mechanisms and the load-displacement diagrams for each energy level.